DOI: 10.1148/rg.283075100
RadioGraphics 2008;28:837-853
© RSNA, 2008
MR Imaging of Nonmalignant Penile Lesions1
Alexander P. S. Kirkham, FRCR,
Rowland O. Illing, MRCS,
Suks Minhas, FRCS,
Suks Minhas, FRCS, and
Clare Allen, FRCR
1 From the Departments of Imaging (A.P.S.K., R.O.I., C.A.) and Urology (S.M.), University College London Hospitals NHS Foundation Trust, 235 Euston Rd, London NW1 2BU, England. Recipient of a Certificate of Merit award for an education exhibit at the 2006 RSNA Annual Meeting. Received May 7, 2007; revision requested June 8; final revision received September 26; accepted September 26. All authors have no financial relationships to disclose.
Address correspondence to A.P.S.K. (e-mail: alexkirkham{at}yahoo.com).
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Abstract
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Magnetic resonance (MR) imaging is potentially useful in the assessment of many benign penile diseases. When T1- and T2-weighted sequences are used, MR imaging can clearly delineate the tunica albuginea and can be used to diagnose penile fracture and Peyronie disease; in both conditions, MR imaging may help refine the surgical approach. It is also useful in cases of priapism; in these cases, intravenously administered contrast material can help assess the viability of the corpora cavernosa and the presence of penile fibrosis. In the assessment of a penile prosthesis, MR imaging provides excellent anatomic information and is the investigation of choice. In the evaluation of erectile dysfunction, MR imaging has limited value, and for urethral stricture, it has not yet proved adequately superior to other modalities to justify its routine use.
© RSNA, 2008
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Introduction
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The penis is a superficial organ in which many diseases can be seen or palpated and is readily imaged at high resolution with ultrasonography (US). In this article, we review the normal anatomy and magnetic resonance (MR) imaging anatomy of the penis and describe MR imaging technique in this setting. In addition, we discuss and illustrate the MR imaging findings in a wide spectrum of pathologic conditions of the penis, including penile fracture, suspensory ligament rupture, priapism, erectile dysfunction, Peyronie disease, penile fibrosis, penile implants, and urethral disorders. We also discuss the need for imaging the penis during tumescence and the usefulness of intravenously administered contrast material.
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Normal Anatomy
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There are some excellent reviews of penile anatomy at MR imaging (1,2), including two reviews in this journal (3,4). The following is a summary of some important points.
The arterial supply to the penis is variable (5) but conventionally occurs on each side from a branch of the internal pudendal artery, namely, the common penile artery. The number of branches is highly variable (6), but classically there are three: (a) the bulbar artery, which supplies the urethra, proximal corpus spongiosum, and bulbospongiosus muscle; (b) the dorsal artery, which supplies the glans penis, distal corpus spongiosum, and penile skin; and (c) the cavernosal arteries, which supply the corpora cavernosa. Helicine branches of the cavernosal arteries supply the endothelium-lined sinusoids; erection occurs by means of vasodilatation in the helicine branches and compression of the subtunical draining veins (7). The most proximal part (mean length, 2.3 cm) of the cavernosal arteries lies outside the corpora cavernosa, running dorsally near the midline and often covered by the deep dorsal veins. They penetrate the corpus cavernosum at a point 1 cm distal to the most distal attachment of the crura to the ischium, where the cavernosal bodies join (5).
The septum separating the corpora cavernosa is fenestrated and porous: contrast material injected into one corpus cavernosum will leak into the other (8), and one patent cavernosal artery can supply enough blood for tumescence of the entire penis. Arterial communication between the corpora cavernosa and the corpus spongiosum is limited. During erection, intracavernosal pressure approximates systolic pressure (9), and the corpus spongiosum needs to be at a much lower pressure to allow ejaculation.
Venous drainage is via superficial and deep systems, which usually communicate via small anastomoses (10). The superficial system drains the penile skin and superficial fascial layers via the superficial dorsal vein, which empties into the superficial venous system of the pelvis (10). The deep fascia of the penis, or Buck fascia, separates the superficial and deep systems. Descriptions of the deep system vary, and there are several variable veins on the dorsum of the penis that communicate via anastomoses and drain into the pelvis via the preprostatic or internal pudendal veins (10). The largest and most constant vein is the deep dorsal vein, which drains the corpus spongiosum via circumflex veins and the corpora cavernosa via emissary veins (11). Recent evidence suggests that the deep system also drains most of the blood from the glans penis. In most cases, there are smaller cavernosal veins lying lateral to the deep vein, usually draining separately into the pelvis (11). These veins lie deep to the deep dorsal vein within their own vascular sheath. Some authors describe them as extending for most of the length of the penis (11); others describe them as coursing proximally from the hilum (12). Finally, small veins accompany the dorsal arteries (11).
Both the corpus spongiosum and the corpora cavernosa are surrounded by a fibrous sheath known as the tunica albuginea, which has inner (circular) and outer (longitudinal) layers (Fig 1) (11). Outside this sheath lie the deep dorsal arteries and veins. A tough, enveloping layer of deep fascia (Buck fascia) surrounds the deep vessels and the corpora cavernosa and fuses proximally with the deep fascia of the urogenital region. Outside the Buck fascia lie the superficial vessels in a loose fascial layer (sometimes termed the Dartos fascia), continuous with the Colles fascia of the perineum and containing a few thin dartos muscle fibers. Hematoma or urine arising deep to an intact Buck fascia is confined to the penis. In contrast, blood or hematoma lying in the superficial fascia may extend to the scrotum and abdominal wall (13).
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MR Imaging Anatomy
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Both the corpora cavernosa and the corpus spongiosum have intermediate to high signal intensity with T1-weighted sequences and high signal intensity with T2-weighted sequences (Figs 2–4). The corpus spongiosum is isointense relative to the glans penis and may be hyper- or hypointense relative to the corpora cavernosa with T2-weighted sequences (1). Variable layering effects are a normal finding in the tumescent corpora cavernosa (Fig 2c). The contrast between high signal intensity within the corpora and the fascial layers of the penis is higher with T2-weighted sequences than with T1-weighted sequences (3).
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Figure 2a. Axial T2-weighted (a, c) and T1-weighted (b) MR images obtained through the middle of the penis in three different patients after the intracavernosal injection of prostaglandin E1 show the tunica albuginea (black arrowheads) and the Buck fascia (white arrowheads in a and b, seen as a discreet entity at the dorsum and laterally). Thick white arrows in a indicate the superficial dorsal veins; thin white arrows in a and b indicate the deep dorsal vessels; black arrows indicate the cavernosal arteries; * indicates the urethra, which lies in the middle of the corpus spongiosum. Note the layering of blood within the corpora cavernosa in c, a normal finding during tumescence. In many patients, the tunica albuginea and Buck fascia cannot be clearly differentiated.
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Figure 2b. Axial T2-weighted (a, c) and T1-weighted (b) MR images obtained through the middle of the penis in three different patients after the intracavernosal injection of prostaglandin E1 show the tunica albuginea (black arrowheads) and the Buck fascia (white arrowheads in a and b, seen as a discreet entity at the dorsum and laterally). Thick white arrows in a indicate the superficial dorsal veins; thin white arrows in a and b indicate the deep dorsal vessels; black arrows indicate the cavernosal arteries; * indicates the urethra, which lies in the middle of the corpus spongiosum. Note the layering of blood within the corpora cavernosa in c, a normal finding during tumescence. In many patients, the tunica albuginea and Buck fascia cannot be clearly differentiated.
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Figure 2c. Axial T2-weighted (a, c) and T1-weighted (b) MR images obtained through the middle of the penis in three different patients after the intracavernosal injection of prostaglandin E1 show the tunica albuginea (black arrowheads) and the Buck fascia (white arrowheads in a and b, seen as a discreet entity at the dorsum and laterally). Thick white arrows in a indicate the superficial dorsal veins; thin white arrows in a and b indicate the deep dorsal vessels; black arrows indicate the cavernosal arteries; * indicates the urethra, which lies in the middle of the corpus spongiosum. Note the layering of blood within the corpora cavernosa in c, a normal finding during tumescence. In many patients, the tunica albuginea and Buck fascia cannot be clearly differentiated.
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Figure 3. Sagittal T2-weighted MR image obtained close to the midline after the intracavernosal injection of prostaglandin E1 shows the tunica albuginea (thin black arrows), corpus spongiosum (white arrow), suspensory ligament (black arrowheads), and bulbospongiosus muscle (thick black arrows). White arrowhead indicates the point of entry of the urethra into the roof of the bulb.
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Figure 4. Coronal T2-weighted MR image obtained through the base of the penis after the intracavernosal injection of prostaglandin E1 shows the ischiocavernosus (white arrowhead) and bulbocavernosus (black arrowhead) muscles. The urethra is just visible entering the roof of the bulb (arrow). The inferior pubic ramiare also seen (*).
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The tunica albuginea is readily seen around the corpora cavernosa but is thinner around the corpus spongiosum, an important point in the assessment of penile fracture (14). 
Connective tissue and fat between the tunica albuginea and Buck fascia in the midline posteriorly contains the low-signal-intensity deep dorsal vessels (with the vein and sometimes the arteries seen on axial images) and often allows the two structures to be differentiated for the dorsal part of their circumference (11); laterally, they are usually apposed but can sometimes be differentiated with T1-weighted sequences, with which the Buck fascia has slightly higher signal intensity than the tunica albuginea. The superficial dorsal vein may be seen outside the Buck fascia in the midline. After the intravenous administration of contrast material, enhancement in the corpora cavernosa radiates axially from the cavernosal arteries and from proximal to distal (15), a point that may have important implications for the imaging of fistulas.
The most proximal part of the corpus spongiosum is the bulb, surrounded by the low-signal-intensity bulbospongiosus muscle (Fig 3). Its roof is pierced by the urethra, which then runs centrally within the corpus spongiosum and has intermediate to low signal intensity with T1- and T2-weighted sequences. The most proximal part of the corpora cavernosa are the crura, which are attached to the ischium with their medial parts covered by the low-signal-intensity ischiocavernosus muscle (1).
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MR Imaging Technique
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Our mainstay for MR imaging of the penis is thin-section (
4-mm) high-resolution (matrix of at least 256 x 192) spin-echo T2-weighted sequences performed in orthogonal planes with use of a surface coil. The sequences are performed with a small field of view and without fat suppression. All of the images in this article were obtained with these parameters on a 1.5-T magnet. In addition, we usually perform spin-echo T1-weighted sequences in the axial plane. One of the strengths of MR imaging is the anatomic information it provides, and it helps if the imaging planes are anatomically correct. Taping the penis to the anterior abdominal wall in the midline, with padding if necessary, helps to achieve this. Short inversion time inversion-recovery or fat-saturated images can help identify thin layers of fluid or edematous soft tissue in the imaging of prostheses or infection.
As in the imaging of penile tumors (16), routine use of intravenous contrast material is not necessary, but there are several situations (described in the following sections) in which it may be useful. It may show enhancing plaques in Peyronie disease (17) or help demonstrate the urethral mucosa in cases of fracture (14), and is vital in cases of priapism to demonstrate perfusion of the corpora cavernosa and help predict necrosis. For dynamic contrast-enhanced imaging, usually performed in cases of priapism, we obtain three-dimensional fat-saturated gradient-echo volumes with approximately 30-second acquisitions, a matrix size of 150 x 256, a section width of 3 mm, and four contrast-enhanced scans. These are followed by axial or coronal contrast-enhanced spin-echo T1-weighted sequences.
Erection
We routinely inject 10 µg of prostaglandin E1 (alprostadil), except in cases of priapism, acute penile fracture, painful erection, or penile prosthesis. Prostaglandin E1 demonstrates deformities seen in tumescence and provides far superior images of the tunica albuginea and of fibrotic change within the corpora cavernosa. For erectile dysfunction, the dose may be increased to 20 µg (especially if this larger dose has been administered before), and in young patients with normal erections it can be reduced to 5 µg. Sildenafil administration and manual stimulation achieve a good result in most patients but involve a longer time to onset and are not as reliable as intracavernosal agents (18).
Contraindications for intracavernosal prostaglandin E1 include implants and conditions that predispose to priapism (sickle cell disease, myeloma, polycythemia). Tumors invading the corpora cavernosa, anatomic abnormalities, and clotting derangement are only relative contraindications (19). The risk of priapism is small (~1% in a large group of patients with erectile dysfunction of mixed cause [20] and one of nine patients in a small study of penile cancer [16]), and priapism can usually be treated with evacuation of the corpora cavernosa or by pharmacologic means (21).
Safety
All current inflatable penile prostheses can be safely imaged with MR imaging. There is a theoretic risk of heat transfer from water-filled devices within the transmitting coil, but to our knowledge there have been no reports of such an occurrence (22). Two malleable prostheses (OmniPhase and DuraPhase; Dacomed, Minneapolis, Minn) containing metallic elements show fairly strong deflection with 1.5-T magnets (23) and should not be imaged.
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Trauma: Penile Fracture
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Penile fracture is a rare, traumatic, usually unilateral rupture of the tunica albuginea that most often occurs during sexual intercourse but sometimes occurs during masturbation or after falling on the erect penis (24). A cracking sensation and severe pain are followed by rapid detumescence and bruising. It is a surgical emergency and, if unrepaired, may lead to deformity and erectile dysfunction (25). There have been three recent MR imaging studies of acute penile fractures in a total of 25 patients in whom the diagnosis was clinically suspected (4,14,26).
Imaging should be performed with the patient’s penis in the erect position to prevent kinking between the pendulous and fixed parts and to closely approximate the penis and the surface coil (14). The key finding is disruption of the low-signal-intensity tunica albuginea, which is well seen on both T1- and T2-weighted images (Fig 5). Although contrast is better with T2-weighted sequences, T1-weighted sequences may help detect more subtle fractures: In one study, the defect in the tunica albuginea was well seen only with T1-weighted sequences in three of four patients (14). A possible explanation is that acute hematoma may have low signal intensity on T2-weighted images and thereby mimic the intact tunica albuginea (14). In two studies, MR imaging helped identify three patients with painful posttraumatic hematoma (either intracavernosal or outside the tunica albuginea) without disruption of the tunica albuginea, thereby obviating surgical exploration (Fig 6) (26). Rupture of the dorsal vein of the penis is a rare mimic of acute fracture and should be distinguished from a fracture at MR imaging (27).
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Figure 5a. Acute penile fracture in a 30-year-old man. Sagittal T2-weighted (a) and axial T1-weighted (b) contrast-enhanced spin-echo MR images show a defect in the tunica albuginea (arrowhead), with altered signal intensity in both the adjacent corpus cavernosum and the subcutaneous tissues.
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Figure 5b. Acute penile fracture in a 30-year-old man. Sagittal T2-weighted (a) and axial T1-weighted (b) contrast-enhanced spin-echo MR images show a defect in the tunica albuginea (arrowhead), with altered signal intensity in both the adjacent corpus cavernosum and the subcutaneous tissues.
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Figure 6a. Intracavernosal hematoma in a 20-year-old man with a history of recent trauma and a palpable lump at the dorsum of the penis. (a) Sagittal T2-weighted MR image shows a high-signal-intensity lesion (arrow). The tunica albuginea is intact, and the penis is not fractured. (b) On an axial contrast-enhanced T1-weighted MR image, the lesion (arrow) still has high signal intensity but has not enhanced significantly. (c) On a T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 5 months later, the lesion (arrow) shows partial resolution and has uniformly low signal intensity.
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Figure 6b. Intracavernosal hematoma in a 20-year-old man with a history of recent trauma and a palpable lump at the dorsum of the penis. (a) Sagittal T2-weighted MR image shows a high-signal-intensity lesion (arrow). The tunica albuginea is intact, and the penis is not fractured. (b) On an axial contrast-enhanced T1-weighted MR image, the lesion (arrow) still has high signal intensity but has not enhanced significantly. (c) On a T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 5 months later, the lesion (arrow) shows partial resolution and has uniformly low signal intensity.
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Figure 6c. Intracavernosal hematoma in a 20-year-old man with a history of recent trauma and a palpable lump at the dorsum of the penis. (a) Sagittal T2-weighted MR image shows a high-signal-intensity lesion (arrow). The tunica albuginea is intact, and the penis is not fractured. (b) On an axial contrast-enhanced T1-weighted MR image, the lesion (arrow) still has high signal intensity but has not enhanced significantly. (c) On a T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 5 months later, the lesion (arrow) shows partial resolution and has uniformly low signal intensity.
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Several groups have found that accurate delineation of the site of fracture may enable the surgeon to use a small focal incision (14,26), rather than the extensive subcoronal degloving approach that has been used in the past and probably has a higher prevalence of complications (28).
Contrast enhancement may be useful for several reasons. First, acute hematoma may be isointense relative to the corpora cavernosa with T1-weighted sequences, so that intracavernosal hematoma is well seen only as an enhancement defect after contrast material administration (14). Second, in acute fracture, dynamic contrast enhancement may show early focal enhancement at the site of rupture (14). Other investigators have found that in some cases contrast enhancement helped define the defect more clearly but are not convinced that it is routinely indicated (4).
It is important to image the corpus spongiosum accurately because an associated urethral injury is seen in 22%–30% of acute fractures, although it is often only a small, partial tear (14). MR imaging may help confirm urethral injury, but whether it can replace retrograde urethrography is uncertain, and current data are limited (14).
Should MR imaging be used routinely in penile fracture? The case for its superseding cavernosography—an invasive, painful procedure with significant false-negative results—is strong (29). US can help detect defects in the tunica albuginea in the majority of patients (although false-negative results do occur) (30) and can also depict the hematoma and injuries of the corpus spongiosum and urethra. The problem with US in difficult cases is the lack of tissue contrast, especially in the detumescent pendulous part of the penis, and the one small study (four patients) that compared US and MR imaging found that US was not helpful, whereas MR imaging was much more informative (31). The answer probably depends on the clinical findings: If the defect can be palpated, imaging may be unnecessary, and if the only doubt is about urethral injury, retrograde urethrography can be performed quickly and cheaply. In equivocal cases, MR imaging may help make the diagnosis and help keep the incision small; in a small number of patients, the diagnosis of rupture may confidently be excluded, thereby obviating surgical exploration.
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Suspensory Ligament Rupture
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The suspensory ligament supports the penis in both the flaccid (32) and erect (33) states and has been the subject of renewed interest over the last 20 years, since its division can result in a significant apparent increase in penis length (34). Injury most commonly occurs during sexual intercourse with forceful downward pressure and may lead to penile deformity or instability (33). The ligament consists of three parts (32). A longer, anterior part, the fundiform ligament, divides to encircle (while remaining discrete from) the corpora cavernosa and their tunica albuginea, supporting them like a hammock. More posteriorly, the suspensory ligament proper essentially lies in the midline and divides around the dorsal vein to blend with the tunica albuginea of the corpora cavernosa. Yet more posteriorly, the smaller, shorter arcuate subpubic ligament runs for a short distance from the most posterior part of the symphysis pubis, which lies closest to the penis. Although the three parts of the suspensory ligament are difficult to differentiate at MR imaging, the ligament as a whole is readily seen (Fig 3) (1,32), and rupture appears as a disruption of the normally well-defined low-signal-intensity strands with T2-weighted sequences (Fig 7).
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Figure 7. Traumatic rupture of the suspensory ligament in a 53-year-old man. Sagittal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows a heterogeneous area inferior to the inferior pubic ramus (arrow) (compare the clearly visible suspensory ligament in Fig 3). Note the associated irregularity of the tunica albuginea (arrowheads).
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Should MR imaging be used routinely to image suspensory ligament rupture? To our knowledge, no data exist on its efficacy in this setting, but we have noted that the reliable clinical sign of rupture—a palpable gap between the symphysis pubis and penis—occurs in less than one-half of patients (33) and have found MR imaging helpful in an equivocal case. Once the diagnosis has been made, surgical repair allows a good cosmetic and functional outcome (33).
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Priapism
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Priapism is defined as prolonged, painful erection. It can usefully be divided into two types: high or low flow. Low-flow (anoxic) priapism is the more common type and is a form of compartment syndrome; as elsewhere in the body, if untreated it leads to infarction and fibrosis (35). Low-flow priapism is usually a disorder of venous outflow and has many causes, including recreational and therapeutic drugs (including sildenafil and intracavernosal agents), sickle cell disease, leukemia, and malignant infiltration, although 30%–50% of cases are idiopathic (36). High-flow priapism is at least initially associated with well-oxygenated corpora cavernosa and is usually caused by trauma or surgery, with the formation of an arteriolacunar fistula, although an intermittent form occurs in sickle cell disease, often with a low-flow component (35). High-flow priapism does not constitute an emergency and can even be treated conservatively (37). Patient history and clinical examination are usually sufficient to distinguish the two types: High-flow priapism is not usually as painful as the low-flow type, and the tumescence is less complete, with pulsation sometimes visible in the penis. Measurement of oxygenation in aspirated blood is often diagnostic for the ischemic low-flow state, but Doppler US of the cavernosal arteries can be useful in difficult cases (38).
How can MR imaging help in priapism? There are two possible indications for MR imaging, the first of which is the imaging of traumatic arteriovenous fistulas in high-flow states (Fig 8). Both US and selective arteriography have proved useful in showing the arteriolacunar fistula: US shows an area of turbulent high flow, sometimes with enlarged feeding vessels or draining veins, whereas selective arteriography shows a characteristic blush (37). The problem with MR imaging is one of resolution: It cannot depict small vessels as clearly as either high-frequency US or angiography, especially with the dynamic sequences that would be required to show early enhancement in a fistula. The enhancement pattern in this situation (and the presence of a flow void with different sequences) has not yet been characterized, but it is unlikely that MR imaging will replace the combination of US and angiography (which can be followed, if necessary, by therapeutic embolization) in this setting.
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Figure 8a. Arteriovenous fistula in an 18-year-old man with posttraumatic high-flow priapism. (a) Coronal T2-weighted MR image shows heterogeneous signal intensity in the left corpus cavernosum (arrow). (b) Coronal dynamic contrast-enhanced gradient-echo MR image shows early enhancement in the left corpus cavernosum (arrow). (c) Selective angiogram of the left internal pudendal artery shows an early blush in the same area (arrow), a finding that is diagnostic for an arteriovenous fistula. White lines outline the shaft of the penis.
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Figure 8b. Arteriovenous fistula in an 18-year-old man with posttraumatic high-flow priapism. (a) Coronal T2-weighted MR image shows heterogeneous signal intensity in the left corpus cavernosum (arrow). (b) Coronal dynamic contrast-enhanced gradient-echo MR image shows early enhancement in the left corpus cavernosum (arrow). (c) Selective angiogram of the left internal pudendal artery shows an early blush in the same area (arrow), a finding that is diagnostic for an arteriovenous fistula. White lines outline the shaft of the penis.
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Figure 8c. Arteriovenous fistula in an 18-year-old man with posttraumatic high-flow priapism. (a) Coronal T2-weighted MR image shows heterogeneous signal intensity in the left corpus cavernosum (arrow). (b) Coronal dynamic contrast-enhanced gradient-echo MR image shows early enhancement in the left corpus cavernosum (arrow). (c) Selective angiogram of the left internal pudendal artery shows an early blush in the same area (arrow), a finding that is diagnostic for an arteriovenous fistula. White lines outline the shaft of the penis.
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The second possible indication for MR imaging in priapism is to help detect infarcted tissue in low-flow states (Figs 9, 10). If the cavernosal infarction is extensive, the corpora cavernosa can be evacuated and a penile prosthesis implanted in a one-step procedure (33). Although blood gas measurement and surgical biopsy can provide similar information, they cannot provide the same anatomic delineation of infarction. In addition, MR imaging may demonstrate malignant infiltration of the corpora cavernosa, for which the treatment may be completely different (Fig 11).
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Figure 9a. Tissue infarction in a 35-year-old man with sickle cell disease and low-flow priapism. On subtracted axial dynamic contrast-enhanced gradient-echo MR images, the corpora cavernosa are completely nonenhancing (*), but the corpus spongiosum enhances strongly (arrow in b).
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Figure 9b. Tissue infarction in a 35-year-old man with sickle cell disease and low-flow priapism. On subtracted axial dynamic contrast-enhanced gradient-echo MR images, the corpora cavernosa are completely nonenhancing (*), but the corpus spongiosum enhances strongly (arrow in b).
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Figure 10a. Consequences of priapism. (a, b) Coronal T1-weighted (a) and axial T2-weighted (b) contrast-enhanced spin-echo MR images obtained in a 40-year-old man after bilateral shunt placement for low-flow priapism show that the procedure was successful on the right side, where the corpus cavernosum (arrow) shows normal enhancement. The procedure was unsuccessful on the left side, where the corpus cavernosum (*) has started to infarct; it is heterogeneous, expanded, and nonenhancing. The urethra has been catheterized. (c) Sagittal T2-weighted MR image obtained in a different patient with a history of prolonged high-flow priapism shows fibrosis. The low signal intensity in the corpus cavernosum (white arrows) contrasts with the normal high signal intensity in the corpus spongiosum (black arrow).
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Figure 10b. Consequences of priapism. (a, b) Coronal T1-weighted (a) and axial T2-weighted (b) contrast-enhanced spin-echo MR images obtained in a 40-year-old man after bilateral shunt placement for low-flow priapism show that the procedure was successful on the right side, where the corpus cavernosum (arrow) shows normal enhancement. The procedure was unsuccessful on the left side, where the corpus cavernosum (*) has started to infarct; it is heterogeneous, expanded, and nonenhancing. The urethra has been catheterized. (c) Sagittal T2-weighted MR image obtained in a different patient with a history of prolonged high-flow priapism shows fibrosis. The low signal intensity in the corpus cavernosum (white arrows) contrasts with the normal high signal intensity in the corpus spongiosum (black arrow).
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Figure 10c. Consequences of priapism. (a, b) Coronal T1-weighted (a) and axial T2-weighted (b) contrast-enhanced spin-echo MR images obtained in a 40-year-old man after bilateral shunt placement for low-flow priapism show that the procedure was successful on the right side, where the corpus cavernosum (arrow) shows normal enhancement. The procedure was unsuccessful on the left side, where the corpus cavernosum (*) has started to infarct; it is heterogeneous, expanded, and nonenhancing. The urethra has been catheterized. (c) Sagittal T2-weighted MR image obtained in a different patient with a history of prolonged high-flow priapism shows fibrosis. The low signal intensity in the corpus cavernosum (white arrows) contrasts with the normal high signal intensity in the corpus spongiosum (black arrow).
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Figure 11a. Pitfall in priapism. (a) Contrast-enhanced spin-echo T1-weighted MR image obtained in a 38-year-old man with low-flow priapism shows reduced enhancement at the tips of the corpora cavernosa (arrows), a finding that is consistent with fibrosis and represents a common pattern. Given that more than 50% of the corpora cavernosa showed enhancement, the patient did not proceed to immediate evacuation and implantation. (b) Coronal contrast-enhanced T1-weighted MR image obtained in a 59-year-old man shows an unusual pattern of enhancement that is irregular, peripheral, and more prominent at the tips of the corpora cavernosa (arrowheads). This finding was considered suggestive of shunting, either paraneoplastic or from tumor infiltration. Histologic analysis of an open biopsy specimen confirmed the latter finding (metastases from a known renal cell carcinoma).
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Figure 11b. Pitfall in priapism. (a) Contrast-enhanced spin-echo T1-weighted MR image obtained in a 38-year-old man with low-flow priapism shows reduced enhancement at the tips of the corpora cavernosa (arrows), a finding that is consistent with fibrosis and represents a common pattern. Given that more than 50% of the corpora cavernosa showed enhancement, the patient did not proceed to immediate evacuation and implantation. (b) Coronal contrast-enhanced T1-weighted MR image obtained in a 59-year-old man shows an unusual pattern of enhancement that is irregular, peripheral, and more prominent at the tips of the corpora cavernosa (arrowheads). This finding was considered suggestive of shunting, either paraneoplastic or from tumor infiltration. Histologic analysis of an open biopsy specimen confirmed the latter finding (metastases from a known renal cell carcinoma).
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Partial penile thrombosis is a rare cause of pain, palpable lump, and priapism. It is well seen with T1- and T2-weighted sequences (3) and can be confirmed with the use of intravenous contrast material.
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Erectile Dysfunction
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Erectile dysfunction of vascular origin may be caused by an arterial inflow disorder or by venous occlusion. The radiologist’s current tools for distinguishing between these two causes are (a) US, which is specific and sensitive for arteriogenic impotence but less so for veno-occlusive disease; and (b) cavernosometry with intracavernosal injection of prostaglandin E1, the standard of reference for veno-occlusive disease (39,40). Conventional angiography may delineate the cause of arteriogenic impotence and can be followed with angioplasty or stent placement to improve inflow. MR imaging has a very limited role in this armamentarium, providing only noninvasive evaluation of the vascular supply to the penis in cases of arteriogenic impotence. There is little doubt that it is inferior to conventional angiography in this setting (41).
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Peyronie Disease
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One cause of erectile dysfunction that is well depicted at MR imaging is Peyronie disease, a poorly understood acquired condition associated with penile curvature and a palpable plaque in the tunica albuginea and adjacent corpus cavernosum (17). Peyronie disease is surprisingly common, with a prevalence of around 3% (42). Its cause is uncertain, but the typically dorsal location and the presence of fibrin in plaques are consistent with an aberrant healing response to minor penile trauma from shear strains (43).
Two clinical phases of Peyronie disease have been described: (a) an acute phase, which is usually associated with pain and sometimes flaccidity during intercourse and varies in duration but typically lasts for 12–18 months (42); and (b) a chronic phase, in which pain is less conspicuous but penile deformity is dominant—typically a dorsal angulation but sometimes ventral or lateral and often associated with shortening. Current practice is to delay surgery until the acute phase is over, to minimize disease recurrence due to active fibrosis (44,45). Such an approach is logical but lacks an evidence base.
Plaques from Peyronie disease are usually palpable and are visible at both US and MR imaging in the majority of cases (17,46,47). They appear as low-signal-intensity areas of thickening in the tunica albuginea with both T1- and T2-weighted sequences (Fig 12) (17). In a recent study comparing US with MR imaging in 57 patients with palpable plaques, 68% of plaques were detected at US and 61% at MR imaging, although the difference was not significant (17). US is far superior in the detection of plaque calcification (17), but the anatomic deformity, including more subtle abnormalities (such as waisting) that affect the surgical approach (48), is better seen with MR imaging.
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Figure 12a. (a) Peyronie disease in a 33-year-old man. Coronal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows a peripheral plaque in the distal left corpus cavernosum (arrow) causing a visible deformity. There is no significant enhancement after contrast material administration. (b, c) Peyronie disease in a 32-year-old man. (b) Coronal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows extensive plaque in the distal corpora cavernosa (arrowheads). (c) Gadolinium-enhanced gradient-echo MR image shows patchy, mild peripheral enhancement (arrows), most prominent in the peripheral plaque on the left side of the image.
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Figure 12b. (a) Peyronie disease in a 33-year-old man. Coronal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows a peripheral plaque in the distal left corpus cavernosum (arrow) causing a visible deformity. There is no significant enhancement after contrast material administration. (b, c) Peyronie disease in a 32-year-old man. (b) Coronal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows extensive plaque in the distal corpora cavernosa (arrowheads). (c) Gadolinium-enhanced gradient-echo MR image shows patchy, mild peripheral enhancement (arrows), most prominent in the peripheral plaque on the left side of the image.
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Figure 12c. (a) Peyronie disease in a 33-year-old man. Coronal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows a peripheral plaque in the distal left corpus cavernosum (arrow) causing a visible deformity. There is no significant enhancement after contrast material administration. (b, c) Peyronie disease in a 32-year-old man. (b) Coronal T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows extensive plaque in the distal corpora cavernosa (arrowheads). (c) Gadolinium-enhanced gradient-echo MR image shows patchy, mild peripheral enhancement (arrows), most prominent in the peripheral plaque on the left side of the image.
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A further proposed benefit of MR imaging is the use of gadolinium-based contrast material to show active inflammation. In two different studies, plaque enhancement (Fig 12) was seen in five of 57 patients (17) and in seven of 20 patients (47), respectively. In all five patients with active inflammation in the study with histologic correlation, enhancement was seen within or around the plaque (n = 4) or focally in the tunica albuginea without thickening (n = 1) (47). However, there is a problem with the use of enhancement to direct the clinical approach: In the only study to examine plaque enhancement, it was never associated with penile pain, our previous indicator of active disease (17). Thus, until prospective studies of outcome have been conducted, the significance of plaque enhancement remains uncertain.
Which patients should undergo MR imaging for Peyronie disease? MR imaging has two potential roles in this setting. The first potential indication is for the detection of impalpable plaques, which are often seen in patients with Peyronie disease (47). However, we do not know the clinical significance of these smaller plaques.
The main indication for MR imaging in Peyronie disease, however, is the accurate depiction of deformity, tunical thickness, plaque position, and cavernosal diameter in cases in which surgery may be complex. For this purpose, MR imaging is clearly superior to US.
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Penile Fibrosis
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Peyronie disease is the most common cause of penile fibrosis, but it may also occur with prolonged priapism, after trauma (especially untreated fracture), after the removal of a penile prosthesis, and with the use of intracavernosal agents for erectile dysfunction (particularly papaverine) (49). Both US and MR imaging can demonstrate areas of fibrosis in the tunica albuginea and the normally homogeneous corpora cavernosa (Fig 13), but there is the potential for overdiagnosis: Echogenic fine strands are often found in the corpora cavernosa in asymptomatic patients at US, although these strands are more prominent with fibrosis. The fact that penile plaques are seen at autopsy in 22% of men may also be relevant (50). It is not known whether US or MR imaging is more useful clinically; the only studies with histologic confirmation involved patients with Peyronie disease.
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Figure 13a. Posttraumatic penile fibrosis in a 38-year-old man. * indicates the urethra. (a) Axial T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows areas of low signal intensity in the corpora cavernosa (arrows), more prominent on the left side. (b) US image obtained with a 10-MHz linear probe shows hyperechoic areas of fibrosis (arrows) that correspond to the low-signal-intensity areas seen at MR imaging.
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Figure 13b. Posttraumatic penile fibrosis in a 38-year-old man. * indicates the urethra. (a) Axial T2-weighted MR image obtained after the intracavernosal injection of prostaglandin E1 shows areas of low signal intensity in the corpora cavernosa (arrows), more prominent on the left side. (b) US image obtained with a 10-MHz linear probe shows hyperechoic areas of fibrosis (arrows) that correspond to the low-signal-intensity areas seen at MR imaging.
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Penile Implants
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Both semirigid and inflatable penile implants have been on the market for at least 30 years (51). The inflatable type are more complex, requiring implantation of a pump and reservoir balloon, but allow complete flaccidity and erection in the great majority of patients, as long as the implant is inflated and deflated regularly to prevent scar tissue formation. The reservoir is usually placed in the prevesical space, and the pump lies in the scrotum. The components of inflatable type implants are connected by silicone tubing and are usually filled with normal saline solution, sometimes containing radiologic contrast material (51). One variant of the three-piece system, the Ambicor (American Medical Systems, Minnetonka, Minn), combines the reservoir and pump into what is known as a "resipump." The composition of the cylinders varies: Those made by Mentor (Santa Barbara, Calif) are a polyurethane derivative, whereas those made by American Medical Systems are a three-layer combination of Dacron-Lycra and silicone (51).
The semirigid systems are simpler to implant but always result in a compromise between rigidity and flaccidity. They consist of either a metallic core surrounded by silicone, articulating segments of polyethylene held together by a central spring, or a malleable silicone cylinder (51).
Penile implants have high levels of patient satisfaction, but they are second-line therapies because (a) they are irreversible, with scar tissue rapidly forming around the device (51); and (b) complications are fairly common and can be serious. Infection occurs in 2%–4% of cases but is significantly more prevalent in revisions or in patients with spinal cord injury (52). Subclinical infections occur more frequently, often manifesting as chronic pain or device migration, and some bacterial colonization is demonstrable in around two-fifths of all implants (52). Mechanical failure rates have decreased considerably in 30 years and are less than 10% at 5 years with most devices (51). Tissue erosion or extrusion is rare, with each complication occurring in only about 1% of cases (53). Another rare complication is a hypermobile glans penis, leading to a characteristic "supersonic transporter" deformity (54). Pain during inflation of penile prostheses is more common and may often be due to "buckling" of the implant. Indeed, in a study of patients who experienced pain more than 2 months after implantation, an abnormality was identified at MR imaging in all 14 patients, whereas physical examination was abnormal in only five (55). Surgical revision in five patients resulted in resolution of the pain, and the finding of buckling was rare in pain-free control subjects.
MR imaging can clearly demonstrate the position of both semirigid and inflatable prostheses (Figs 14–16). The saline solution in inflatable devices is well seen with T2-weighted sequences, and identification of incomplete inflation or a collapsed system is not difficult (56). The silicone in semirigid devices has low signal intensity on T2-weighted images. Ideally, studies of inflatable devices should include both "inflation" and "deflation" sequences, since pain and deformity of the cylinders may in some cases be due to sizing problems: In the study of 14 patients with buckling of the prosthesis described earlier, four patients had excessively long implants for the corporal space (55). Fibrosis causing incomplete inflation or deformity can also be seen at MR imaging (56), as can periprosthetic fluid and inflammation in cases of infection (Fig 14) (55). The role of contrast enhancement in the detection of infection has not been examined but might be a fruitful area for study: How often might we detect subclinical infection causing pain?
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Figure 14. Prosthesis infection in a 40-year-old man. Axial T2-weighted MR image shows infection from a malleable penile prosthesis. The two implants in the corpora cavernosa (*) have low signal intensity and are surrounded by areas of high signal intensity. Note the presence of fluid that has tracked through the Buck fascia and lies in the subcutaneous tissues (arrows).
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Figure 15a. Penile prosthesis in a 58-year-old man. Sagittal (a) and axial (b) T2-weighted MR images show a malleable penile prosthesis (*) with low signal intensity. In this case, the prosthesis (consisting mainly of silicone) is rotationally unstable and has become twisted during imaging, but the components remain in separate corpora cavernosa; there is no evidence of erosion. White arrowheads indicate the corpus spongiosum.
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Figure 15b. Penile prosthesis in a 58-year-old man. Sagittal (a) and axial (b) T2-weighted MR images show a malleable penile prosthesis (*) with low signal intensity. In this case, the prosthesis (consisting mainly of silicone) is rotationally unstable and has become twisted during imaging, but the components remain in separate corpora cavernosa; there is no evidence of erosion. White arrowheads indicate the corpus spongiosum.
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Figure 16a. (a–c) Normal inflatable penile prosthesis in a 69-year-old man. The prosthesis consists of a cavernosal component (*), a pump (p), and a reservoir (r), with tubing (arrowheads) joining these components. On the first two images, obtained in the coronal (a) and sagittal (b) planes, the prosthesis is fully inflated. On a second sagittal T2-weighted MR image (c), the prosthesis is incompletely inflated. Partial deflation can lead to the erroneous diagnosis of buckling. (d) Mentor inflatable prosthesis in a different patient. Coronal T2-weighted MR image shows the proximal parts of both cavernosal components of the inflatable prosthesis (arrows) lying in one corpus cavernosum. Such crossover is a rare complication. p = pump.
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Figure 16b. (a–c) Normal inflatable penile prosthesis in a 69-year-old man. The prosthesis consists of a cavernosal component (*), a pump (p), and a reservoir (r), with tubing (arrowheads) joining these components. On the first two images, obtained in the coronal (a) and sagittal (b) planes, the prosthesis is fully inflated. On a second sagittal T2-weighted MR image (c), the prosthesis is incompletely inflated. Partial deflation can lead to the erroneous diagnosis of buckling. (d) Mentor inflatable prosthesis in a different patient. Coronal T2-weighted MR image shows the proximal parts of both cavernosal components of the inflatable prosthesis (arrows) lying in one corpus cavernosum. Such crossover is a rare complication. p = pump.
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Figure 16c. (a–c) Normal inflatable penile prosthesis in a 69-year-old man. The prosthesis consists of a cavernosal component (*), a pump (p), and a reservoir (r), with tubing (arrowheads) joining these components. On the first two images, obtained in the coronal (a) and sagittal (b) planes, the prosthesis is fully inflated. On a second sagittal T2-weighted MR image (c), the prosthesis is incompletely inflated. Partial deflation can lead to the erroneous diagnosis of buckling. (d) Mentor inflatable prosthesis in a different patient. Coronal T2-weighted MR image shows the proximal parts of both cavernosal components of the inflatable prosthesis (arrows) lying in one corpus cavernosum. Such crossover is a rare complication. p = pump.
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Figure 16d. (a–c) Normal inflatable penile prosthesis in a 69-year-old man. The prosthesis consists of a cavernosal component (*), a pump (p), and a reservoir (r), with tubing (arrowheads) joining these components. On the first two images, obtained in the coronal (a) and sagittal (b) planes, the prosthesis is fully inflated. On a second sagittal T2-weighted MR image (c), the prosthesis is incompletely inflated. Partial deflation can lead to the erroneous diagnosis of buckling. (d) Mentor inflatable prosthesis in a different patient. Coronal T2-weighted MR image shows the proximal parts of both cavernosal components of the inflatable prosthesis (arrows) lying in one corpus cavernosum. Such crossover is a rare complication. p = pump.
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Overall, MR imaging is clearly superior to physical examination for prostheses with associated pain and deformity and should be considered in difficult cases. The role of contrast enhancement is uncertain.
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Urethral Disorders
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Anterior urethral strictures are most commonly investigated with retrograde urethrography and voiding cystourethrography. US urethrography is probably more accurate for the detection of strictures in the anterior urethra; can provide additional information about spongiofibrosis; and is probably better at helping detect stones, false tracts, and diverticula (57). MR imaging needs to be superior to US in evaluating the anterior urethra to justify the expense and technical difficulty of achieving urethral distention. To our knowledge, there have been no studies comparing the two modalities in this context. MR imaging has, however, been compared with retrograde urethrography and has been shown to have advantages similar to those of US: improved definition of spongiofibrosis and better definition of fistula and tumor (58). The combination of intravenous administration of contrast agent 70 minutes before an MR imaging study with angiographic sequences has recently been shown to provide information comparable to that provided by retrograde urethrography, although the additional benefits of this technique are uncertain (59); there is good contrast between urine and the urethra with unenhanced T2-weighted sequences (58). There is also emerging evidence that MR imaging can provide more accurate information in cases of obliterative stricture than can combined retrograde-anterograde urethrography, particularly in complex cases of pelvic trauma, and is good for assessing the degree of prostatic displacement (60). The usual method involves the instillation of jelly into the anterior urethra, combined with a way of occluding or compressing the meatus during the study to prevent leakage (58,60). Periurethral contrast enhancement at MR imaging correlates with histologic evidence of tissue inflammation (61), but we do not yet know how clinically useful this correlation is.
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Other Abnormalities
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The excellent soft-tissue contrast of MR imaging means that many other abnormalities of the penis are well demonstrated. Congenital penile disorders are rare, but MR imaging may be the preferred modality owing to its capacity to image the proximal corpora cavernosa and bulbar urethra in cases of abnormal morphology (1). MR imaging has also been useful in cases of ambiguous genitalia (62).
The Cowper glands are paired structures that lie within the urogenital diaphragm and drain via ducts that pass through the external urethral sphincter. These ducts may rarely become dilated, forming a syringocele that is classified according to the presence and nature of a connection with the urethra (63). The syringocele is well demonstrated with T2-weighted sequences (3).
Periurethral abscess is also well depicted with T2-weighted sequences (3). Although the periurethral injection of collagen can cause confusing appearances if the patient’s clinical history is not known, the collagen is generally well defined and has intermediate to low signal intensity on both T1- and T2-weighted images (2).
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Conclusions
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Although MR imaging is potentially useful in almost all nonmalignant penile diseases except erectile dysfunction, there are only a few applications in which it should be used routinely. One is assessment of a penile prosthesis, for which MR imaging is clearly superior to any other modality. In priapism, penile fracture, and penile fibrosis, it is a useful problem-solving tool. As a method for urethrography, its usefulness is unproved.
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References
|
|---|
- Hricak H, Marotti M, Gilbert TJ, et al. Normal penile anatomy and abnormal penile conditions: evaluation with MR imaging. Radiology 1988;169(3): 683–690.[Abstract/Free Full Text]
- Vossough A, Pretorius ES, Siegelman ES, Ramchandani P, Banner MP. Magnetic resonance imaging of the penis. Abdom Imaging 2002;27(6): 640–659.[CrossRef][Medline]
- Pretorius ES, Siegelman ES, Ramchandani P, Banner MP. MR imaging of the penis. RadioGraphics 2001;21(spec no):S283–S299.[Abstract/Free Full Text]
- Choi MH, Kim B, Ryu JA, Lee SW, Lee KS. MR imaging of acute penile fracture. RadioGraphics 2000;20(5):1397–1405.[Abstract/Free Full Text]
- Martinez-Pineiro L, Julve E, Martinez-Pineiro JA. Topographical anatomy of the penile arteries. Br J Urol 1997;80(3):463–467.[Medline]
- Bookstein JJ, Lang EV. Penile magnification pharmacoarteriography: details of intrapenile arterial anatomy. AJR Am J Roentgenol 1987;148(5): 883–888.[Abstract/Free Full Text]
- Benoit G, Delmas V, Gillot C, Jardin A. The anatomy of erection. Surg Radiol Anat 1987;9(4): 263–272.[CrossRef][Medline]
- Velcek D, Evans JA. Cavernosography. Radiology 1982;144(4):781–785.[Abstract/Free Full Text]
- Kromann-Andersen B, Nielsen KK, Nordling J. Cavernosometry: methodology and reproducibility with and without pharmacological agents in the evaluation of venous impotence. Br J Urol 1991; 67(5):517–521.[Medline]
- Moscovici J, Galinier P, Hammoudi S, Lefebvre D, Juricic M, Vaysse P. Contribution to the study of the venous vasculature of the penis. Surg Radiol Anat 1999;21(3):193–199.[Medline]
- Hsu GL, Hsieh CH, Wen HS, Chen YC, Chen SC, Mok MS. Penile venous anatomy: an additional description and its clinical implication. J Androl 2003;24(6):921–927.[Abstract/Free Full Text]
- Breza J, Aboseif SR, Orvis BR, Lue TF, Tanagho EA. Detailed anatomy of penile neurovascular structures: surgical significance. J Urol 1989;141 (2):437–443.[Medline]
- Bertolotto M, Mucelli RP. Nonpenetrating penile traumas: sonographic and Doppler features. AJR Am J Roentgenol 2004;183(4):1085–1089.[Free Full Text]
- Uder M, Gohl D, Takahashi M, et al. MRI of penile fracture: diagnosis and therapeutic follow-up. Eur Radiol 2002;12(1):113–120.[CrossRef][Medline]
- Kaneko K, De Mouy EH, Lee BE. Sequential contrast-enhanced MR imaging of the penis. Radiology 1994;191(1):75–77.[Abstract/Free Full Text]
- Scardino E, Villa G, Bonomo G, et al. Magnetic resonance imaging combined with artificial erection for local staging of penile cancer. Urology 2004;63(6):1158–1162.[CrossRef][Medline]
- Hauck EW, Hackstein N, Vosshenrich R, et al. Diagnostic value of magnetic resonance imaging in Peyronie’s disease: a comparison both with palpation and ultrasound in the evaluation of plaque formation. Eur Urol 2003;43(3):293–300.[CrossRef][Medline]
- Bacar MM, Batislam E, Altinok D, Yilmaz E, Bacar H. Sildenafil citrate for penile hemodynamic determination: an alternative to intracavernosal agents in Doppler ultrasound evaluation of erectile dysfunction. Urology 2001;57(4):623–627.[CrossRef][Medline]
- Hatzimouratidis K, Hatzichristou DG. A comparative review of the options for treatment of erectile dysfunction: which treatment for which patient? Drugs 2005;65(12):1621–1650.[CrossRef][Medline]
- Linet OI, Ogrinc FG. Efficacy and safety of intracavernosal alprostadil in men with erectile dysfunction. The Alprostadil Study Group. N Engl J Med 1996;334(14):873–877.[Abstract/Free Full Text]
- Muruve N, Hosking DH. Intracorporeal phenylephrine in the treatment of priapism. J Urol 1996; 155(1):141–143.[CrossRef][Medline]
- Shellock FG, Kanal E. Magnetic resonance: bioeffects, safety and patient management. Philadelphia, Pa: Lippincott Williams & Wilkins, 1996; 144–205.
- Shellock FG, Morisoli S, Kanal E. MR procedures and biomedical implants, materials, and devices: 1993 update. Radiology 1993;189(2):587–599.[Abstract/Free Full Text]
- Al Saleh BM, Ansari ER, Al Ali IH, Tell JY, Saheb A. Fractures of the penis seen in Abu Dhabi. J Urol 1985;134(2):274–275.[Medline]
- Kalash SS, Young JD Jr. Fracture of penis: controversy of surgical versus conservative treatment. Urology 1984;24(1):21–24.[CrossRef][Medline]
- Abolyosr A, Moneim AE, Abdelatif AM, Abdalla MA, Imam HM. The management of penile fracture based on clinical and magnetic resonance imaging findings. BJU Int 2005;96(3):373–377.[CrossRef][Medline]
- Nehru-Babu M, Hendry D, Ai-Saffar N. Rupture of the dorsal vein mimicking fracture of the penis. BJU Int 1999;84(1):179–180.[CrossRef][Medline]
- Morris SB, Miller MA, Anson K. Management of penile fracture. J R Soc Med 1998;91(8):427–428.[Medline]
- Grosman H, Gray RR, St Louis EL, Casey R, Keresteci AG, Elliott DS. The role of corpus cavernosography in acute "fracture" of the penis. Radiology 1982;144(4):787–788.[Free Full Text]
- Dierks PR, Hawkins H. Sonography and penile trauma. J Ultrasound Med 1983;2(9):417–419.[Medline]
- Fedel M, Venz S, Andreessen R, Sudhoff F, Loening SA. The value of magnetic resonance imaging in the diagnosis of suspected penile fracture with atypical clinical findings. J Urol 1996;155(6): 1924–1927.[CrossRef][Medline]
- Hoznek A, Rahmouni A, Abbou C, Delmas V, Colombel M. The suspensory ligament of the penis: an anatomic and radiologic description. Surg Radiol Anat 1998;20(6):413–417.[CrossRef][Medline]
- Li CY, Agrawal V, Minhas S, Ralph DJ. The penile suspensory ligament: abnormalities and repair. BJU Int 2007;99(1):117–120.[CrossRef][Medline]
- Spyropoulos E, Christoforidis C, Borousas D, Mavrikos S, Bourounis M, Athanasiadis S. Augmentation phalloplasty surgery for penile dysmorphophobia in young adults: considerations regarding patient selection, outcome evaluation and techniques applied. Eur Urol 2005;48(1): 121–128.[CrossRef][Medline]
- Pryor J, Akkus E, Alter G, et al. Priapism. J Sex Med 2004;1(1):116–120.[CrossRef][Medline]
- El-Bahnasawy MS, Dawood A, Farouk A. Low-flow priapism: risk factors for erectile dysfunction. BJU Int 2002;89(3):285–290.[CrossRef][Medline]
- Hakim LS, Kulaksizoglu H, Mulligan R, Greenfield A, Goldstein I. Evolving concepts in the diagnosis and treatment of arterial high flow priapism. J Urol 1996;155(2):541–548.[CrossRef][Medline]
- Wilkins CJ, Sriprasad S, Sidhu PS. Colour Doppler ultrasound of the penis. Clin Radiol 2003;58(7): 514–523.[CrossRef][Medline]
- Golijanin D, Singer E, Davis R, Bhatt S, Seftel A, Dogra V. Doppler evaluation of erectile dysfunction. I. Int J Impot Res 2007;19(1):37–42.[CrossRef][Medline]
- Golijanin D, Singer E, Davis R, Bhatt S, Seftel A, Dogra V. Doppler evaluation of erectile dysfunction. II. Int J Impot Res 2007;19(1):43–48.[CrossRef][Medline]
- John H, Kacl GM, Lehmann K, Debatin JF, Hauri D. Clinical value of pelvic and penile magnetic resonance angiography in preoperative evaluation of penile revascularization. Int J Impot Res 1999; 11(2):83–86.[CrossRef][Medline]
- Schwarzer U, Sommer F, Klotz T, Braun M, Reifenrath B, Engelmann U. The prevalence of Peyronie’s disease: results of a large survey. BJU Int 2001;88 (7):727–730.[CrossRef][Medline]
- Jalkut M, Gonzalez-Cadavid N, Rajfer J. Peyronie’s disease: a review. Rev Urol 2003;5(3):142–148.[Medline]
- Kadioglu A, Akman T, Sanli O, Gurkan L, Cakan M, Celtik M. Surgical treatment of Peyronie’s disease: a critical analysis. Eur Urol 2006;50(2): 235–248.[CrossRef][Medline]
- Pryor J, Akkus E, Alter G, et al. Peyronie’s disease. J Sex Med 2004;1(1):110–115.[CrossRef][Medline]
- Andresen R, Wegner HE, Miller K, Banzer D. Imaging modalities in Peyronie’s disease: an intrapersonal comparison of ultrasound sonography, x-ray in mammography technique, computerized tomography, and nuclear magnetic resonance in 20 patients. Eur Urol 1998;34(2):128–135.[CrossRef][Medline]
- Helweg G, Judmaier W, Buchberger W, et al. Peyronie’s disease: MR findings in 28 patients. AJR Am J Roentgenol 1992;158(6):1261–1264.[Abstract/Free Full Text]
- Levine LA, Lenting EL. A surgical algorithm for the treatment of Peyronie’s disease. J Urol 1997; 158(6):2149–2152.[CrossRef][Medline]
- Moemen MN, Hamed HA, Kamel II, Shamloul RM, Ghanem HM. Clinical and sonographic assessment of the side effects of intracavernous injection of vasoactive substances. Int J Impot Res 2004;16(2):143–145.[CrossRef][Medline]
- Smith BH. Subclinical Peyronie’s disease. Am J Clin Pathol 1969;52(4):385–390.[Medline]
- Mulcahy JJ, Austoni E, Barada JH, et al. The penile implant for erectile dysfunction. J Sex Med 2004;1 (1):98–109.[CrossRef][Medline]
- Carson CC. Diagnosis, treatment and prevention of penile prosthesis infection. Int J Impot Res 2003; 15(suppl 5):S139–S146.[CrossRef][Medline]
- Carson CC, Mulcahy JJ, Govier FE. Efficacy, safety and patient satisfaction outcomes of the AMS 700CX inflatable penile prosthesis: results of a long-term multicenter study. AMS 700CX Study Group. J Urol 2000;164(2):376–380.[CrossRef][Medline]
- Mulhall JP, Kim FJ. Reconstructing penile supersonic transporter (SST) deformity using glanulopexy (glans fixation). Urology 2001;57(6): 1160–1162.[CrossRef][Medline]
- Moncada I, Hernandez C, Jara J, et al. Buckling of cylinders may cause prolonged penile pain after prosthesis implantation: a case control study using magnetic resonance imaging of the penis. J Urol 1998;160(1):67–71.[CrossRef][Medline]
- Thiel DD, Broderick GA, Bridges M. Utility of magnetic resonance imaging in evaluating inflatable penile prosthesis malfunction and complaints. Int J Impot Res 2003;15(suppl 5):S155–S161.[CrossRef][Medline]
- Gupta N, Dubey D, Mandhani A, Srivastava A, Kapoor R, Kumar A. Urethral stricture assessment: a prospective study evaluating urethral ultrasonography and conventional radiological studies. BJU Int 2006;98(1):149–153.[CrossRef][Medline]
- Osman Y, El-Ghar MA, Mansour O, Refaie H, El-Diasty T. Magnetic resonance urethrography in comparison to retrograde urethrography in diagnosis of male urethral strictures: is it clinically relevant? Eur Urol 2006;50(3):587–594.[CrossRef][Medline]
- Yekeler E, Suleyman E, Tunaci A, et al. Contrast-enhanced 3D MR voiding urethrography: preliminary results. Magn Reson Imaging 2004;22(9): 1193–1199.[CrossRef][Medline]
- Sung DJ, Kim YH, Cho SB, et al. Obliterative urethral stricture: MR urethrography versus conventional retrograde urethrography with voiding cystourethrography. Radiology 2006;240(3):842–848.[Abstract/Free Full Text]
- Pavlica P, Barozzi L, Menchi I. Imaging of male urethra. Eur Radiol 2003;13(7):1583–1596.[CrossRef][Medline]
- Secaf E, Hricak H, Gooding CA, et al. Role of MRI in the evaluation of ambiguous genitalia. Pediatr Radiol 1994;24(4):231–235.[CrossRef][Medline]
- Bevers RF, Abbekerk EM, Boon TA. Cowper’s syringocele: symptoms, classification and treatment of an unappreciated problem. J Urol 2000;163(3): 782–784.[CrossRef][Medline]
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Abstract
Introduction
