DOI: 10.1148/rg.274065171
RadioGraphics 2007;27:989-1004
© RSNA, 2007
Imaging of Marfan Syndrome: Multisystemic Manifestations1
Hong Il Ha, MD,
Joon Beom Seo, MD,
Sang Hoon Lee, MD,
Joon-Won Kang, MD,
Hyun Woo Goo, MD,
Tae-Hwan Lim, MD, and
Myung Jin Shin, MD
1 From the Departments of Radiology and the Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2 dong, Songpa-gu, Seoul 138-736, Korea. Presented as an education exhibit at the 2005 RSNA Annual Meeting. Received September 18, 2006; revision requested October 24 and received December 18; accepted December 18. All authors have no financial relationships to disclose.
Address correspondence to J.B.S. (e-mail: seojb{at}amc.seoul.kr).
 |
Abstract
|
|---|
Marfan syndrome is an inherited multisystemic connective-tissue disease that is caused by a mutation of the fibrillin-1 gene. The syndrome is characterized by a wide range of clinical manifestations. Common cardiovascular manifestations, most of which are substantial contributors to mortality, include annuloaortic ectasia with or without aortic valve insufficiency, aortic dissection, aortic aneurysm, pulmonary artery dilatation, and mitral valve prolapse. Scoliosis, pectus excavatum and carinatum, arachnodactyly, and acetabular protrusion are common musculoskeletal manifestations. Dural ectasia is a characteristic central nervous system manifestation. In some patients with Marfan syndrome, there is also pulmonary and ocular involvement. Early identification and treatment of these conditions contribute to an improved quality of life and a life expectancy close to the average for the general population in the United States. Radiologists play a key role in the diagnosis of Marfan syndrome. Knowledge about the various manifestations of Marfan syndrome and awareness of their radiologic appearances permit a comprehensive diagnostic approach that allows better patient care.
© RSNA, 2007
|
Introduction
|
|---|
Marfan syndrome is a multisystemic connective-tissue disorder that occurs worldwide and affects both sexes equally. Its prevalence has been estimated at 2–3 persons per 10,000 (1). Marfan syndrome is commonly found in athletes such as basketball and volleyball players, who tend to have tall stature and relatively long extremities (2). It is an autosomal dominant inherited disorder, but about 25%–30% of cases represent sporadic mutations. The fibrillin-1 gene (FBN1) on chromosome 15 contains at least 65 exons and spans about 235 kb of genomic DNA. It encodes a large glycoprotein that is a major component of extra-cellular microfibrils found in a wide range of tissues. More than 135 mutations have been identified in FBN1. Most of these are missense mutations that change a codon for one amino acid into a codon specifying another amino acid. Abnormal microfibrils from mutations of FBN1, either alone or in association with elastin in the elastic fiber, are responsible for various clinical manifestations. Microfibrils connect elastic laminae to adjacent endothelial cells and smooth muscle cells, contribute to structural integrity, and coordinate contractile and elastic tensions of the vessel wall. Dysfunction of microfibrils induces fragmentation of elastic fibers and impairment of elastic tissue homeostasis. It produces structural disintegration and elastolysis of vascular connective tissue, which ultimately result in aneurysm formation and dissection. Furthermore, mutation of FBN1 affects the regulation of tissue growth factor signaling, which is related to the pathogenesis of bone overgrowth, pulmonary manifestations, valve change, and aortic dilatation (3–5). There is striking intrafamilial and individual variability in the clinical manifestations of Marfan syndrome, variability that is suggestive of some degree of genotype-phenotype correlation. Mutations in exon 24–32 are implicated in neonatal Marfan syndrome and atypically severe Marfan syndrome. Mild manifestations, such as various combinations of ophthalmic and musculoskeletal abnormalities without aortic dilatation, are suggestive of mutations in exon 1–10 or 59–65 (6).
Marfan syndrome may affect various systems, including the cardiovascular, musculoskeletal, central nervous, pulmonary, ocular, and integumentary systems. Potential cardiovascular manifestations include annuloaortic ectasia with or without aortic valve insufficiency, aortic aneurysm, aortic dissection, mitral valve prolapse, and pulmonary artery dilatation. In addition, there may be a wide range of musculoskeletal manifestations, including scoliosis, chest wall deformity, arachnodactyly, and acetabular protrusion (1,7). Possible central nervous system manifestations include dural ectasia, which usually is asymptomatic but may be represented by neurologic symptoms such as back pain, headache, or meningocele-related signs and symptoms (8,9). Pneumothorax and bullae are potential pulmonary manifestations. Among various ocular manifestations, ectopia lentis or retinal detachment may occur. Last, the possible integumentary manifestations include striae atrophicae and recurrent or incisional hernia. The diagnosis of Marfan syndrome is based on a combination of the major and minor clinical features described in the 1986 Berlin classification system, which was revised by expert consensus to create the 1996 Ghent classification system. The presence of either two major features and one minor feature or of one major feature and four minor features supports a diagnosis of Marfan syndrome (Table) (7). Aortic dissection, congestive heart failure, and cardiac valve disease are the most common causes of death in more than 90% of those affected by Marfan syndrome and, thus, the primary causes of reduction in life expectancy. However, over the past 30 years, improvements in diagnostic techniques and in medical and surgical therapeutic strategies have led to a considerable increase in the life expectancy of those with Marfan syndrome, boosting it to a nearly normal level (10,11).
The article describes the various systemic manifestations of Marfan syndrome, with emphasis on the most important diagnostic imaging features.
|
Cardiovascular Manifestations
|
|---|
Annuloaortic Ectasia and Aortic Aneurysm
The aortic root consists of the annulus, sinuses of Valsalva, and sinotubular junction. The annulus, a firm fibrous band that surrounds the aorta and leaflets of the aortic valve, is located at the aorto-ventricular junction. The Valsalva sinus is a dilatation of the aortic root just above the aortic valve. At its upper level, at a point known as the sinotubular junction, the Valsalva sinus becomes the tubular ascending aorta (12). Annuloaortic ectasia, especially with dilatation of the aortic root, is found in 60%–80% of adults with Marfan syndrome. It usually begins with dilatation of the aortic sinuses, which progresses into the sinotubular junction and ultimately into the aortic annulus. Dilatation of the aortic root is the leading cause of aortic valve insufficiency in Marfan syndrome. In annuloaortic ectasia, severe aortic regurgitation occurs that may progress to aortic root dissection or rupture (13). In histologic specimens, the aortic wall demonstrates medial degeneration of the elastic tissue with cystic medial necrosis of the smooth muscle cells (Fig 1). This degenerative change and destruction of medial elastic fibers produce aortic stiffening and ultimately result in the loss of normal distensibility of the aorta, thereby exacerbating the dilatation of the aortic wall (14,15). Aortic aneurysm without annuloaortic ectasia also is common. Compared with atherosclerotic aortic aneurysms, aortic aneurysms in Marfan syndrome commonly occur in younger patients and enlarge more rapidly (16).
View larger version (212K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1a. Histologic specimens from the aorta in a 24-year-old man show evidence of cystic medial necrosis. (a) Photomicrograph (original magnification, x40; hematoxylin-eosin stain) shows deposition of mucopolysaccharide (*). (b) Photomicrograph (original magnification, x100; Masson trichrome stain) demonstrates disruption of the elastic lamina.
|
|
View larger version (221K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1b. Histologic specimens from the aorta in a 24-year-old man show evidence of cystic medial necrosis. (a) Photomicrograph (original magnification, x40; hematoxylin-eosin stain) shows deposition of mucopolysaccharide (*). (b) Photomicrograph (original magnification, x100; Masson trichrome stain) demonstrates disruption of the elastic lamina.
|
|
Annuloaortic ectasia may produce various degrees of dilatation of the aortic root as observed at computed tomography (CT) (Figs 2, 3). The diameters of the dilated ascending aorta, sinotubular junction, and aortic root are clearly demonstrated on multiplanar CT images obtained with three-dimensional reconstruction techniques (Fig 2). The morphologic characteristics and functions of the aortic valve may be evaluated by using electrocardiographically gated CT with retrospective reconstruction of multiple cardiac phases (Figs 3, 4). The aortic valve opening is clearly demonstrated at 10% of the R-R interval (midsystole). The aortic valve closure is demonstrated at 70% of the R-R interval (middiastole). On midsystolic phase images, the cusps of the aortic valve appear tethered instead of demonstrating their normal arching appearance; the tethered appearance results from the dilatation of the Valsalva sinus. On end-diastolic phase images, valvular insufficiency is depicted as a triangular coaptation defect (Fig 4). Electrocardiographically gated CT images provide a clear and detailed depiction of the structural features of the aortic root (including the diameter of each segment and coaptation of the cusps) and the proximal segments of the coronary arteries. Accurate visualization of these anatomic structures is important for surgical planning and postoperative evaluation (17–19).
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2. Annuloaortic ectasia without valvular insufficiency in a 44-year-old woman. Multiplanar reformatted CT image shows the abnormal aortic root (double-ended arrow) with dilatation of the Valsalva sinus and an indistinct sinotubular junction.
|
|
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3a. Annuloaortic ectasia without valvular insufficiency in a 20-year-old man. Multiplanar reformatted CT images from the systolic (a) and diastolic (b) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in a), and the absence of a coaptation defect (* in b). Echocardiography helped confirm the absence of aortic valve insufficiency.
|
|
View larger version (133K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3b. Annuloaortic ectasia without valvular insufficiency in a 20-year-old man. Multiplanar reformatted CT images from the systolic (a) and diastolic (b) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in a), and the absence of a coaptation defect (* in b). Echocardiography helped confirm the absence of aortic valve insufficiency.
|
|
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4a. Annuloaortic ectasia with severe valvular insufficiency in a 32-year-old man. (a) Reformatted CT image shows marked dilatation of the Valsalva sinus and the sinotubular junction (arrowheads). (b, c) Reformatted CT images from the systolic (b) and diastolic (c) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in b), and a central coaptation defect (* in c). (d) Postoperative reformatted CT image, obtained after aortic valve–sparing aortic annuloplasty, shows a normal appearance of the aortic root. Arrows indicate the prosthetic ring used to reconstruct the annulus. (e, f) Reformatted CT images from the systolic (e) and diastolic (f) phases show relief of tethering of leaflets (arrowheads in e) and disappearance of the central coaptation defect.
|
|
View larger version (164K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4b. Annuloaortic ectasia with severe valvular insufficiency in a 32-year-old man. (a) Reformatted CT image shows marked dilatation of the Valsalva sinus and the sinotubular junction (arrowheads). (b, c) Reformatted CT images from the systolic (b) and diastolic (c) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in b), and a central coaptation defect (* in c). (d) Postoperative reformatted CT image, obtained after aortic valve–sparing aortic annuloplasty, shows a normal appearance of the aortic root. Arrows indicate the prosthetic ring used to reconstruct the annulus. (e, f) Reformatted CT images from the systolic (e) and diastolic (f) phases show relief of tethering of leaflets (arrowheads in e) and disappearance of the central coaptation defect.
|
|
View larger version (162K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4c. Annuloaortic ectasia with severe valvular insufficiency in a 32-year-old man. (a) Reformatted CT image shows marked dilatation of the Valsalva sinus and the sinotubular junction (arrowheads). (b, c) Reformatted CT images from the systolic (b) and diastolic (c) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in b), and a central coaptation defect (* in c). (d) Postoperative reformatted CT image, obtained after aortic valve–sparing aortic annuloplasty, shows a normal appearance of the aortic root. Arrows indicate the prosthetic ring used to reconstruct the annulus. (e, f) Reformatted CT images from the systolic (e) and diastolic (f) phases show relief of tethering of leaflets (arrowheads in e) and disappearance of the central coaptation defect.
|
|
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4d. Annuloaortic ectasia with severe valvular insufficiency in a 32-year-old man. (a) Reformatted CT image shows marked dilatation of the Valsalva sinus and the sinotubular junction (arrowheads). (b, c) Reformatted CT images from the systolic (b) and diastolic (c) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in b), and a central coaptation defect (* in c). (d) Postoperative reformatted CT image, obtained after aortic valve–sparing aortic annuloplasty, shows a normal appearance of the aortic root. Arrows indicate the prosthetic ring used to reconstruct the annulus. (e, f) Reformatted CT images from the systolic (e) and diastolic (f) phases show relief of tethering of leaflets (arrowheads in e) and disappearance of the central coaptation defect.
|
|
View larger version (151K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4e. Annuloaortic ectasia with severe valvular insufficiency in a 32-year-old man. (a) Reformatted CT image shows marked dilatation of the Valsalva sinus and the sinotubular junction (arrowheads). (b, c) Reformatted CT images from the systolic (b) and diastolic (c) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in b), and a central coaptation defect (* in c). (d) Postoperative reformatted CT image, obtained after aortic valve–sparing aortic annuloplasty, shows a normal appearance of the aortic root. Arrows indicate the prosthetic ring used to reconstruct the annulus. (e, f) Reformatted CT images from the systolic (e) and diastolic (f) phases show relief of tethering of leaflets (arrowheads in e) and disappearance of the central coaptation defect.
|
|
View larger version (165K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4f. Annuloaortic ectasia with severe valvular insufficiency in a 32-year-old man. (a) Reformatted CT image shows marked dilatation of the Valsalva sinus and the sinotubular junction (arrowheads). (b, c) Reformatted CT images from the systolic (b) and diastolic (c) phases show dilated aortic sinuses, tethering of leaflets (arrowheads in b), and a central coaptation defect (* in c). (d) Postoperative reformatted CT image, obtained after aortic valve–sparing aortic annuloplasty, shows a normal appearance of the aortic root. Arrows indicate the prosthetic ring used to reconstruct the annulus. (e, f) Reformatted CT images from the systolic (e) and diastolic (f) phases show relief of tethering of leaflets (arrowheads in e) and disappearance of the central coaptation defect.
|
|
An aortic aneurysm appears as a cystic or fusiform dilatation of the aorta on chest or abdominal CT scans. Compared with atherosclerotic aneurysms, the aortic aneurysms seen in Marfan syndrome rarely show intimal calcification or atherosclerotic thrombosis, and they occur commonly and develop more rapidly in younger patients (Fig 5). The broad spectrum of causes of aortic aneurysm includes atherosclerosis, other connective-tissue disorders, infectious or inflammatory aortitis, Behçet disease, and congenital abnormality. Atherosclerotic aneurysms are the most common type, usually are seen in the elderly, and typically are characterized by intimal calcification and fibrous plaques along the aorta. The imaging characteristics of aortic aneurysms in Ehlers-Danlos syndrome resemble those in Marfan syndrome. Aneurysms produced by a bacterial or fungal infection commonly involve the ascending aorta and frequently are seen in patients with predisposing factors (an immunocompromised condition, endocarditis, sepsis, drug abuse, or trauma). Syphilitic aneurysm, which is rare and is seen only in patients with untreated tertiary syphilis, has a saccular appearance and involves the ascending aorta and aortic arch more commonly than the thoracoabdominal aorta. Infrequently, aortic aneurysm occurs in inflammatory aortitis such as that in Behçet disease, rheumatoid arthritis, or spondyloarthropathy (16).
View larger version (112K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5. Abdominal aortic aneurysm in a 27-year-old man with annuloaortic ectasia. Maximum intensity projection CT image shows fusiform dilatation of the infrarenal abdominal aorta (arrowheads).
|
|
Prophylactic surgery for annuloaortic ectasia is recommended when the diameter of the Valsalva sinus exceeds 5.5 cm in an adult and 5.0 cm in a child. Additional considerations that may be indications for such surgery even if the diameter of the Valsalva sinus is less than 5.0 cm are a rapid rate of aortic aneurysm expansion (increase in dilatation by more than 1 cm per year) and a family history of aortic dissection (20–22). Composite surgical replacement of the aortic root and valve commonly has been performed with or without coronary reimplantation with various methods. Surgical techniques reflect an attempt to maintain the native aortic valve so as to avoid the risk of thromboembolism and the need for lifelong anticoagulation therapy with a mechanical prosthetic aortic valve. The remarkable evolution in recent years of new valve-sparing procedures has been focused largely on preserving the function of the native aortic valve (Fig 4) (23–25). Asymptomatic thoracic and abdominal aortic aneurysms with a diameter exceeding 6 cm also are considered indications for prophylactic surgery (20,26).
Aortic Dissection
Aortic dissection is produced by an intimal tear that allows blood to enter the medial layer of the aorta, creating a false lumen. Dissection develops more often in young patients with Marfan syndrome than it does in the general population (27). Multidetector CT is the radiologic modality most frequently used for the diagnosis of aortic dissection, as it has high sensitivity and high specificity. It clearly demonstrates the extent of dissection, the relationship of the true lumen and false lumen, and any involvement of major aortic branch vessels. It also enables the evaluation of additional structures such as the pleural and pericardial spaces. The presence of an aortic dissection is likely when progressive aortic enlargement is observed at serial imaging examinations or when a double contour of the aortic arch or a displacement of intimal calcification by more than 6 mm is seen on radiographs. An enlarged arch is another possible finding of aortic dissection, but it is not specific. A new pleural effusion or a pericardial effusion seen at radiography also may be suggestive of aortic dissection. On CT scans, typical findings of aortic dissection are an intimal flap and a false lumen (Figs 6, 7a). The demonstration of an intimal flap supports a definitive diagnosis of aortic dissection. However, in approximately 30% of cases, the images show neither an intimal flap nor a false lumen. Secondary findings that support a diagnosis of aortic dissection include increased attenuation of the thrombosed false lumen on unenhanced CT scans, internal displacement of intimal calcification, mediastinal or pericardial hematoma, and ischemia or infarction of organs supplied by branch vessels from the false lumen (28). In addition, recurrent aortic dissection is common, and sometimes triple-barreled aortic dissection occurs (Fig 6). Cases of triple-barreled aortic dissection may be divided into two groups according to the location of the third channel. The first group consists of two coexistent dissections, one on either side of the true lumen. The second group consists of dissections in which the new third channel occurs within the wall of the false lumen. Because the outer wall of the false lumen is extremely thin, it ruptures easily, especially in patients with Marfan syndrome (29).
View larger version (92K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6a. Triple-barreled aortic dissection in a 41-year-old man after surgical replacement of the ascending aorta for a DeBakey type I aortic dissection. (a, b) Axial CT scans (a at a level higher than b) show a dissection of the thoracic aorta. (c, d) Axial CT scans obtained 5 months later (c at a level higher than d) show complex dissection flaps (arrowheads).
|
|
View larger version (163K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6b. Triple-barreled aortic dissection in a 41-year-old man after surgical replacement of the ascending aorta for a DeBakey type I aortic dissection. (a, b) Axial CT scans (a at a level higher than b) show a dissection of the thoracic aorta. (c, d) Axial CT scans obtained 5 months later (c at a level higher than d) show complex dissection flaps (arrowheads).
|
|
View larger version (108K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6c. Triple-barreled aortic dissection in a 41-year-old man after surgical replacement of the ascending aorta for a DeBakey type I aortic dissection. (a, b) Axial CT scans (a at a level higher than b) show a dissection of the thoracic aorta. (c, d) Axial CT scans obtained 5 months later (c at a level higher than d) show complex dissection flaps (arrowheads).
|
|
View larger version (173K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6d. Triple-barreled aortic dissection in a 41-year-old man after surgical replacement of the ascending aorta for a DeBakey type I aortic dissection. (a, b) Axial CT scans (a at a level higher than b) show a dissection of the thoracic aorta. (c, d) Axial CT scans obtained 5 months later (c at a level higher than d) show complex dissection flaps (arrowheads).
|
|
View larger version (117K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7a. Bentall procedure in a 42-year-old man with a Stanford type A aortic dissection. (a) Preoperative reformatted CT image shows a thin intimal flap in the ascending aorta (arrow). (b) Postoperative reformatted CT image shows the composite graft and mechanical aortic valve used to replace the aortic root, as well as the reimplanted left coronary artery (arrow), which is attached to the composite graft.
|
|
View larger version (142K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7b. Bentall procedure in a 42-year-old man with a Stanford type A aortic dissection. (a) Preoperative reformatted CT image shows a thin intimal flap in the ascending aorta (arrow). (b) Postoperative reformatted CT image shows the composite graft and mechanical aortic valve used to replace the aortic root, as well as the reimplanted left coronary artery (arrow), which is attached to the composite graft.
|
|
The DeBakey system has been widely used for classification of aortic dissections. The Stanford system is another widely used classification system, in which two types of aortic dissection are differentiated according to whether surgical treatment is needed. When an aortic dissection involves the ascending aorta (Stanford type A), it usually requires surgical repair, which most commonly involves the replacement of the aortic root with a composite graft (Bentall procedure) (Fig 7). An aortic dissection that is confined to the distal part of aortic arch (Stanford type B) usually requires medical treatment for hypertension instead of surgical treatment. If the diameter of the aorta is greater than 4 cm during pregnancy, the risks of a rapid expansion of aortic dilatation and of aortic dissection are increased (20,23).
Pulmonary Artery Dilatation
Dilatation of the main pulmonary artery is one of the established criteria for the diagnosis of Marfan syndrome. Like dilatation of the ascending aorta, it occurs predominantly in the root. The prevalence and prognosis of pulmonary artery dilatation in Marfan syndrome are still unknown. In one study, the upper limits of a normal main pulmonary artery diameter, at the root and at the level of bifurcation, were 34.8 mm and 28.0 mm, respectively (Fig 8) (30,31).
View larger version (126K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8. Dilatation of the main pulmonary artery in a 16-year-old boy. Maximum intensity projection CT image at the level of the Valsalva sinus shows dilatation of the main pulmonary artery trunk to a diameter of 41 mm, as well as annuloaortic ectasia with a sinus diameter of 57 mm.
|
|
|
Musculoskeletal Manifestations
|
|---|
Scoliosis
Scoliosis is a frequent and potentially severe manifestation of Marfan syndrome. It occurs in approximately 62% of those affected. Unlike idiopathic scoliosis, scoliosis in Marfan syndrome is commonly seen in younger patients. There is no difference between the sexes with regard to the frequency of occurrence. Scoliosis in Marfan syndrome is more severe, rigid, and progressive, so it often requires surgical correction (32–35). When it occurs in combination with straight back syndrome, kyphosis, or a chest wall deformity, it may contribute to cardiopulmonary compromise and restriction of lung volume (36).
The radiographic examination of scoliosis includes standing anteroposterior and lateral radiography of the entire spine centered over the scoliotic curve. Measurement of the severity of a scoliotic curve has practical applications not only for selecting patients for surgical treatment but also for monitoring the results of corrective therapy. The Lippman-Cobb method is widely used to measure the degree of scoliotic curvature (Fig 9). CT and MR imaging are helpful to evaluate the bone structure, associated abnormalities of the spinal cord, and the nerve roots before treatment planning (Fig 10).
View larger version (69K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Scoliosis in a 17-year-old boy. (a) Preoperative standing radiograph of the whole spine shows thoracolumbar scoliosis with a leftward curvature of 54° (Lippman-Cobb method). (b) Postoperative standing radiograph shows a reduced thoracolumbar curvature of 30°.
|
|
View larger version (63K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Scoliosis in a 17-year-old boy. (a) Preoperative standing radiograph of the whole spine shows thoracolumbar scoliosis with a leftward curvature of 54° (Lippman-Cobb method). (b) Postoperative standing radiograph shows a reduced thoracolumbar curvature of 30°.
|
|
View larger version (91K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10a. Scoliosis in an 18-year-old man. (a) Preoperative reformatted CT image obtained to plan the positioning of screws. (b, c) Preoperative axial T2-weighted (b) and coronal T2-weighted fast spin-echo (c) MR images obtained to evaluate the spinal cord and nerve root and the relationships of the spinal cord, pedicles, and vertebral bodies. (d, e) Postoperative coronal (d) and sagittal (e) reformatted CT images, obtained to evaluate the placement of instrumentation and to identify complications, show proper positioning of the screws.
|
|
View larger version (162K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10b. Scoliosis in an 18-year-old man. (a) Preoperative reformatted CT image obtained to plan the positioning of screws. (b, c) Preoperative axial T2-weighted (b) and coronal T2-weighted fast spin-echo (c) MR images obtained to evaluate the spinal cord and nerve root and the relationships of the spinal cord, pedicles, and vertebral bodies. (d, e) Postoperative coronal (d) and sagittal (e) reformatted CT images, obtained to evaluate the placement of instrumentation and to identify complications, show proper positioning of the screws.
|
|
View larger version (89K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10c. Scoliosis in an 18-year-old man. (a) Preoperative reformatted CT image obtained to plan the positioning of screws. (b, c) Preoperative axial T2-weighted (b) and coronal T2-weighted fast spin-echo (c) MR images obtained to evaluate the spinal cord and nerve root and the relationships of the spinal cord, pedicles, and vertebral bodies. (d, e) Postoperative coronal (d) and sagittal (e) reformatted CT images, obtained to evaluate the placement of instrumentation and to identify complications, show proper positioning of the screws.
|
|
View larger version (60K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10d. Scoliosis in an 18-year-old man. (a) Preoperative reformatted CT image obtained to plan the positioning of screws. (b, c) Preoperative axial T2-weighted (b) and coronal T2-weighted fast spin-echo (c) MR images obtained to evaluate the spinal cord and nerve root and the relationships of the spinal cord, pedicles, and vertebral bodies. (d, e) Postoperative coronal (d) and sagittal (e) reformatted CT images, obtained to evaluate the placement of instrumentation and to identify complications, show proper positioning of the screws.
|
|
View larger version (59K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10e. Scoliosis in an 18-year-old man. (a) Preoperative reformatted CT image obtained to plan the positioning of screws. (b, c) Preoperative axial T2-weighted (b) and coronal T2-weighted fast spin-echo (c) MR images obtained to evaluate the spinal cord and nerve root and the relationships of the spinal cord, pedicles, and vertebral bodies. (d, e) Postoperative coronal (d) and sagittal (e) reformatted CT images, obtained to evaluate the placement of instrumentation and to identify complications, show proper positioning of the screws.
|
|
There are two methods for preventing the progression of scoliosis: bracing and surgical intervention. Bracing is recommended for curvatures of less than 25°; however, the success rate is about 20%. Curvatures greater than 40° require surgical correction (37,38). Postoperative complications of surgical correction for scoliosis are more common in patients with Marfan syndrome than in the general population. These complications may include bleeding, infection, pseudarthrosis, and failure of correction (eg, laminar fracture with resultant hook dislodgment) or of instrumentation (eg, rod fracture). Complications may be associated with altered lumbosacral anatomy, decreased bone mineral density, and connective-tissue change contributing to ligamentous laxity (33).
Chest Wall Deformity
Approximately 66% of patients with Marfan syndrome have either pectus excavatum or pectus carinatum produced by longitudinal overgrowth of the ribs (1). These deformities are highly progressive during periods of rapid growth in adolescence, and most patients experience a worsening of symptoms during such periods (39). As mentioned above, severe pectus deformity with or without associated scoliosis or lordosis may further compromise respiratory function by reducing total lung capacity, forced vital capacity, and forced expiratory volume in 1 second (40). The severity of pectus excavatum is determined according to the pectus index calculated on the basis of measurements on CT images. The pectus index is calculated by dividing the width of the chest wall at its widest point by the distance between the posterior surface of the sternum and the anterior surface of the spine. A pectus index greater than 3.25 is an indication that surgery is required (41).
Pectus excavatum is depicted on radiographs and CT images as retraction of the lower portion of the sternum and the attached costal cartilages (Fig 11). The heart, lungs, and diaphragm may be compressed and displaced, depending on the severity of the internal depression of the sternum. CT may be used to grade the severity of pectus excavatum and compression of the mediastinal and upper abdominal structures. Pectus carinatum appears at radiography and CT as anterior protrusion of the upper portion of the sternum and the costal cartilages, with bilateral flattening of the sides of the chest (Fig 12).
View larger version (86K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11a. Pectus excavatum and annuloaortic ectasia in a 28-year-old man. (a) Axial CT scan obtained at the level of the aortic root shows severe retraction of the sternum (CT index, 8.5) with resultant compression of the left atrium (*). Marked dilatation of the aortic root also is visible. (b) Postoperative chest radiograph shows a metallic bar positioned beneath the sternum, across the anterior thoracic wall (Nuss procedure), and a mechanical aortic valve replacement. (c) Postoperative axial CT scan obtained at the level of the aortic root shows an increased anteroposterior diameter of the thorax and relief of left atrial compression (*).
|
|
View larger version (155K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11b. Pectus excavatum and annuloaortic ectasia in a 28-year-old man. (a) Axial CT scan obtained at the level of the aortic root shows severe retraction of the sternum (CT index, 8.5) with resultant compression of the left atrium (*). Marked dilatation of the aortic root also is visible. (b) Postoperative chest radiograph shows a metallic bar positioned beneath the sternum, across the anterior thoracic wall (Nuss procedure), and a mechanical aortic valve replacement. (c) Postoperative axial CT scan obtained at the level of the aortic root shows an increased anteroposterior diameter of the thorax and relief of left atrial compression (*).
|
|
View larger version (82K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11c. Pectus excavatum and annuloaortic ectasia in a 28-year-old man. (a) Axial CT scan obtained at the level of the aortic root shows severe retraction of the sternum (CT index, 8.5) with resultant compression of the left atrium (*). Marked dilatation of the aortic root also is visible. (b) Postoperative chest radiograph shows a metallic bar positioned beneath the sternum, across the anterior thoracic wall (Nuss procedure), and a mechanical aortic valve replacement. (c) Postoperative axial CT scan obtained at the level of the aortic root shows an increased anteroposterior diameter of the thorax and relief of left atrial compression (*).
|
|
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12a. Pectus carinatum in a 17-year-old boy. Lateral chest radiograph (a) and axial CT scan at the level of the ventricles (b) show the characteristic anterior protrusion of the lower portion of the sternum and the costal cartilages, with flattening of both sides of the chest.
|
|
View larger version (63K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12b. Pectus carinatum in a 17-year-old boy. Lateral chest radiograph (a) and axial CT scan at the level of the ventricles (b) show the characteristic anterior protrusion of the lower portion of the sternum and the costal cartilages, with flattening of both sides of the chest.
|
|
In patients with Marfan syndrome, surgical repair of pectus excavatum is performed after the skeletal structures have matured, to minimize the likelihood of recurrence. The shape of the thorax stabilizes and is established by mid adolescence.
Two different surgical techniques may be used to correct a chest wall deformity. The Ravitch procedure, the oldest of the two, involves the bilateral resection of costal cartilage and the fracture and repositioning of the sternum, which may be held in place with metal pins until the bone heals; the pins are subsequently removed. The Nuss procedure is currently more widely used because it obviates the broad excision of costal cartilages and invasive restructuring of the sternum; instead, a temporary substernal metallic bar is used to reshape the chest wall (Fig 11). Postoperative complications after a Nuss procedure may include bar rotation or displacement, persistent uncontrolled pain, or wound infection near the stabilizer (42,43). In contrast to surgical repair of pectus excavatum, pectus carinatum repair is performed mainly for cosmetic reasons.
Arachnodactyly
Arachnodactyly is one of the characteristic features of Marfan syndrome, but it often has been seen in other connective-tissue diseases. Although there are no simple diagnostic criteria, radiographic measurement is helpful in confirming the presence of disproportionate metacarpal length. To obtain the metacarpal index, the total length (in millimeters) of the second, third, fourth, and fifth metacarpals is divided by the total width of the metacarpals at their exact midpoints. An index greater than 8.4 or 9.4 may be considered abnormal, depending on the reference standard used (44,45) (Fig 13).
Acetabular Protrusion
Among the various manifestations of Marfan syndrome, acetabular protrusion is rarely mentioned. The prevalence of acetabular protrusion is approximately 16%–27% (46). Acetabular protrusion is a deformity of the hip joint and is distinguished by the invasion of the acetabulum and femoral head into the pelvic cavity. Change in the acetabulum begins during childhood and accelerates during puberty. Most joints in patients with Marfan syndrome are hypermobile; however, acetabular protrusion limits terminal rotation and abduction of the hip joint, so the affected hip is stiff and less efficient biomechanically.
Radiographic findings, including an increased center-edge angle of Wiberg and an obscured teardrop sign, allow the diagnosis. A center-edge angle of Wiberg is formed by a vertical line drawn through the center of the femoral head and a line from the femoral head center to the upper outer margin of the acetabulum. A center-edge angle of 20°–40° is considered normal for adults, and an angle greater than 40° indicates acetabular protrusion. The teardrop sign, which consists of a lateral line formed by the acetabular fossa and a medial line formed by the inner pelvis side wall on anteroposterior radiographic views, is a characteristic finding of normal pelvic structure. In patients with acetabular protrusion, the teardrop is crossed by the ilioischial line or obscured by the femoral head (47,48) (Fig 14).
View larger version (152K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14. Acetabular protrusion in an 18-year-old man. Pelvic radiograph shows medial displacement of the acetabulum (dotted line). The center-edge angle of Wiberg is 54°. The teardrop sign is obscured by the femoral head (arrow).
|
|
Other Musculoskeletal Abnormalities
Planovalgus, a foot deformity seen in Marfan syndrome, is thought to be caused by increased ligamentous laxity. The incidence of pes planus in Marfan syndrome is approximately 25%. Kyphosis and atlantoaxial translation also have been observed, with a prevalence of 16% and 54%, respectively. Other common musculoskeletal manifestations include spinal anomalies such as kyphoscoliosis, Schmorl nodules, straight back syndrome, and spondylolisthesis (32).
|
Dural Ectasia and Associated Central Nervous System Manifestations
|
|---|
Dural ectasia, which has been observed in 56%–65% of patients with Marfan syndrome (49), is a ballooning or significant widening of the dural sac or neural root sleeves. The condition sometimes is accompanied by bone erosion, meningoceles, and arachnoid cysts (8,9). Defective microfibrils, which cause weakening and incompetence of the dural sac, are the cause of ectasia (50). Most occurrences of dural ectasia in Marfan syndrome affect the lumbosacral spine, where the cerebrospinal fluid pressure reaches its highest level when the patient is upright. Although dural ectasia is usually asymptomatic, it sometimes causes back pain, headache, or neurologic deficit. If these symptoms are related to a meningocele or arachnoid cyst, surgical intervention is necessary for decompression or excision of the cyst (9).
Dural ectasia is depicted on radiographs as a widening of the interpediculate distance (ie, an increased ratio of the width of the transverse process to that of the vertebral body). Vertebral body scalloping occurs with a high prevalence in transition vertebrae. Radiography has a high specificity but a low sensitivity for the detection of dural ectasia. MR imaging and CT are the reference standards for diagnosis of dural ectasia because they are capable of clearly showing the extent of ectasia and bone erosion. Dural ectasia appears as widening of the dural sac, dilatation of the nerve root sleeve, and scalloping of vertebral bodies in the lumbosacral spine on MR and CT images. In addition, MR and CT images may demonstrate an accompanying meningocele or arachnoid cyst (51,52) (Fig 15).
View larger version (94K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15a. Dural ectasia and anterior meningocele with hemorrhagic complication in an 18-year-old man. (a) Axial CT scan at the level of the upper sacrum shows diffuse dilatation of the spinal canal and scalloping of vertebral bodies. (b, c) Axial T1-weighted (b) and axial T2-weighted fat-suppressed (c) fast spin-echo MR images at the level of the lower sacrum show a large complicated anterior meningocele with a subacute hemorrhage (*) in the presacral space and a fluid-hemorrhage level indicative of dural ectasia (arrow). A smaller meningocele (arrowhead) is visible along the left sacral nerve. (d) Sagittal contrast-enhanced T1-weighted fat-suppressed fast spin-echo image shows a cerebrospinal fluid–hemorrhage level (arrow) near the area of dural ectasia at the level of the sacrum (arrowheads) and a subacute hematoma in the large meningocele (*).
|
|
View larger version (122K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15b. Dural ectasia and anterior meningocele with hemorrhagic complication in an 18-year-old man. (a) Axial CT scan at the level of the upper sacrum shows diffuse dilatation of the spinal canal and scalloping of vertebral bodies. (b, c) Axial T1-weighted (b) and axial T2-weighted fat-suppressed (c) fast spin-echo MR images at the level of the lower sacrum show a large complicated anterior meningocele with a subacute hemorrhage (*) in the presacral space and a fluid-hemorrhage level indicative of dural ectasia (arrow). A smaller meningocele (arrowhead) is visible along the left sacral nerve. (d) Sagittal contrast-enhanced T1-weighted fat-suppressed fast spin-echo image shows a cerebrospinal fluid–hemorrhage level (arrow) near the area of dural ectasia at the level of the sacrum (arrowheads) and a subacute hematoma in the large meningocele (*).
|
|
View larger version (109K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15c. Dural ectasia and anterior meningocele with hemorrhagic complication in an 18-year-old man. (a) Axial CT scan at the level of the upper sacrum shows diffuse dilatation of the spinal canal and scalloping of vertebral bodies. (b, c) Axial T1-weighted (b) and axial T2-weighted fat-suppressed (c) fast spin-echo MR images at the level of the lower sacrum show a large complicated anterior meningocele with a subacute hemorrhage (*) in the presacral space and a fluid-hemorrhage level indicative of dural ectasia (arrow). A smaller meningocele (arrowhead) is visible along the left sacral nerve. (d) Sagittal contrast-enhanced T1-weighted fat-suppressed fast spin-echo image shows a cerebrospinal fluid–hemorrhage level (arrow) near the area of dural ectasia at the level of the sacrum (arrowheads) and a subacute hematoma in the large meningocele (*).
|
|
View larger version (137K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15d. Dural ectasia and anterior meningocele with hemorrhagic complication in an 18-year-old man. (a) Axial CT scan at the level of the upper sacrum shows diffuse dilatation of the spinal canal and scalloping of vertebral bodies. (b, c) Axial T1-weighted (b) and axial T2-weighted fat-suppressed (c) fast spin-echo MR images at the level of the lower sacrum show a large complicated anterior meningocele with a subacute hemorrhage (*) in the presacral space and a fluid-hemorrhage level indicative of dural ectasia (arrow). A smaller meningocele (arrowhead) is visible along the left sacral nerve. (d) Sagittal contrast-enhanced T1-weighted fat-suppressed fast spin-echo image shows a cerebrospinal fluid–hemorrhage level (arrow) near the area of dural ectasia at the level of the sacrum (arrowheads) and a subacute hematoma in the large meningocele (*).
|
|
|
Pulmonary Manifestations
|
|---|
The lungs are rarely involved in Marfan syndrome; however, various pulmonary manifestations have been described, including interstitial parenchymal disease and honeycombing, diffuse and apical bullous emphysema, congenital malformation of the bronchus, bronchiectasis, and spontaneous pneumothorax. The formation of lung cysts, bullae, or blebs in patients with Marfan syndrome presumably is due to an abnormality of the collagen fibers that causes focal flaccidity and reduced tensile strength in the wall of the terminal bronchioles, with resultant expiratory air trapping. Widening of the airspace, with or without discrete bullae or blebs, may predispose a patient to spontaneous pneumothorax, which is found in 4%–15% of those with Marfan syndrome. Spontaneous pneumothorax also is 10 times more likely to occur in patients with Marfan syndrome than in the general population (53–56) (Fig 16).
View larger version (183K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16a. Spontaneous pneumothorax in a 15-year-old girl. (a) CT projection radiograph shows a linear wisp of high attenuation (arrow) that represents the edge of the retracted visceral pleura in the right hemithorax. (b) Axial CT scan shows several blebs in the left apex, as well as a right pneumothorax.
|
|
View larger version (114K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16b. Spontaneous pneumothorax in a 15-year-old girl. (a) CT projection radiograph shows a linear wisp of high attenuation (arrow) that represents the edge of the retracted visceral pleura in the right hemithorax. (b) Axial CT scan shows several blebs in the left apex, as well as a right pneumothorax.
|
|
|
Ocular Manifestations
|
|---|
Ectopia lentis, or displacement of the lens, is one of the most common ocular manifestations of Marfan syndrome, but it also may be observed in other conditions. The ocular manifestations of Marfan syndrome also may include myopia, flattening of the cornea, increased axial length of the globe, and retinal detachment. Although ocular manifestations are rarely seen in clinical practice, retinal detachment sometimes is depicted at brain imaging with CT or MR imaging (57,58).
|
Summary
|
|---|
Marfan syndrome is a multisystemic connective-tissue disorder that affects primarily the cardiovascular, musculoskeletal, pulmonary, and ocular systems. Increased understanding of the patho-physiologic processes involved in Marfan syndrome and of their optimal treatment, gained over the past century, has allowed improvements in the length and quality of life for those affected. However, early detection and treatment are important to optimize the outcome. With the increasing availability of whole-body imaging with multidetector CT or MR imaging, the role of the radiologist has expanded beyond the simple achievement of a diagnosis of Marfan syndrome to include the co
Top
Abstract
Introduction
