DOI: 10.1148/rg.234025160
(Radiographics. 2003;23:939-949.)
Role of Sonography in Pancreatic Transplantation1
Paul Nikolaidis, MD,
Rajesh S. Amin, MD,
Caroline M. Hwang, MD,
Richard M. McCarthy, MD,
James H. Clark, MD,
Scott A. Gruber, MD, PhD and
Phebe C. Chen, MD
1 From the Department of Radiology, Northwestern University Medical School, 676 N St Clair St, Suite 800, Chicago, IL 60611 (P.N., C.H., R.M.M.); Department of Radiology, Methodist Hospital, Baylor College of Medicine, Houston, Tex (R.S.A.); Departments of Radiology (P.N., P.C.C.) and Pathology (J.H.C.), University of Texas Medical School, Houston; and Department of Surgery, Wayne State University School of Medicine, Detroit, Mich (S.A.G.). Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received November 13, 2002; revision requested February 11, 2003, and received March 24; accepted April 4. Address correspondence to P.N. (e-mail: p-nikolaidis@northwestern.edu).
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Abstract
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Despite recent advancements in surgical technique and immunosuppressive therapy, postoperative complications of pancreatic transplantation are still common. A complex spectrum of such adverse events includes graft rejection, peripancreatic fluid collections, pancreatitis, exocrine leaks, vascular thrombosis, and hemorrhage. Sonography plays a key role in the initial evaluation of the transplanted pancreas. Gray-scale sonography, duplex Doppler imaging, and sonographic guidance for percutaneous biopsy all contribute to posttransplantation evaluation and detection of sequelae. Color and power Doppler imaging offer valuable information regarding the regional vasculature and potential vascular complications. Because gray-scale sonographic findings alone are often nonspecific, several clinical criteria, including those from biochemical analysis of the urine and serum, must be reviewed with the sonographic findings to provide a thorough evaluation of the transplanted pancreas. When used in conjunction with serologic and urinary markers, the findings from sonography can help direct management options or suggest the need for further examination. Therefore, an understanding of the spectrum of complications combined with knowledge concerning the limitations of this imaging modality are essential for proper diagnosis and effective treatment.
© RSNA, 2003
Index Terms: Pancreas, transplantation, 770.451 • Pancreas, US, 770.1298
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LEARNING OBJECTIVES FOR TEST 4
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After reading this article and taking the test, the reader will be able to:
- Describe the different types and basic techniques of pancreatic transplantation.
- Recognize the different postoperative complications that can occur after pancreatic transplantation.
- Discuss the role of sonography in the evaluation of the transplanted pancreas.
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Introduction
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According to the International Pancreas Transplant Registry (IPTR), nearly 1,500 pancreatic transplantations were performed worldwide in 1999 (1). Approximately three-fourths of these operations were done in the United States, with outcomes documented by the United Network for Organ Sharing (UNOS) (1). In patients with diabetes mellitus, pancreatic transplantation is the most effective method of achieving tight glucose control and can potentially stabilize or reverse complications associated with the disease, thus improving quality of life. In the past 15 years, advancements in surgical technique and postoperative management have increased the overall graft survival rate and decreased the mortality rate of pancreatic transplant recipients. Data from the IPTR/UNOS registry from January 1, 1996, to July 11, 2000, demonstrate 1-year graft function rates ranging from 70% to 84% for the different types of pancreatic transplantations performed in the United States (1). Despite these recent accomplishments, postoperative complications such as graft rejection, peripancreatic fluid collections, pancreatitis, exocrine leaks, vascular thrombosis, and hemorrhage are still common.
Imaging of pancreatic transplants is usually undertaken when there is clinical evidence of graft dysfunction, including abnormal biochemical markers. Sonography plays a major role as the first-line modality in the postoperative evaluation of the pancreatic transplant and in the detection of postoperative complications. Computed tomography (CT) may be used to better delineate the extent of associated fluid collections, as it employs a larger field of view. Furthermore, CT may aid in cases in which other intraabdominal or pelvic pathologic conditions are suspected in pancreatic transplant recipients. CT angiography may depict the transplant vasculature in selected cases. There is an emerging role for magnetic resonance (MR) imaging in the evaluation of pancreatic transplant recipients, as the graft itself and peripancreatic fluid collections are well seen with this modality. MR angiography may be used to evaluate vascular anatomy further and may aid in the detection or additional work-up of vascular complications.
Sonographic findings alone are inadequate and must be interpreted in conjunction with several clinical criteria and biochemical analyses (2). Understanding of the spectrum of posttransplantation complications and knowledge of the limitations of sonography are essential for proper diagnosis and effective treatment. This article describes the basic techniques of pancreatic transplantation and correlates anatomic considerations (including histologic findings in cases of acute graft rejection) with the sonographic findings. The role of sonography in posttransplantation evaluation and management is emphasized.
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Types of Pancreatic Transplantation
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Surgical techniques of pancreatic transplantation have evolved dramatically, with improved patient outcome, since the first pancreatic transplantation was performed in 1966 (3). Currently, there are three types of transplantation performed: simultaneous pancreas-kidney (SPK), pancreas after kidney (PAK), and pancreas transplant alone (PTA). In addition, several surgical techniques have been used to manage the exocrine and venous drainage from the transplanted pancreas.
The most commonly used technique for transplantation of a whole pancreas is the systemic-bladder drainage consisting of a duodenopancreatic graft with a duodenovesical anastomosis, illustrated in Figure 1, which depicts a PAK transplantation (4). A 6–10-cm portion of the donor duodenum is removed along with the donor pancreas. Both ends of the donor duodenum are usually inverted and closed with staple lines. The transplanted pancreas is then placed intraperitoneally within the right iliac fossa of the recipient. Vascular reconstruction involves connecting a donor iliac arterial Y-graft (composed of the internal and external branches of the donor common iliac artery) to the donor splenic and superior mesenteric arteries. The splenic and superior mesenteric arteries and splenic vein end blindly. The common iliac portion of the Y-graft is then anastomosed to the common or external iliac artery of the recipient. The venous anastomosis is drained in the systemic circulation via the common or external iliac vein.
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Figure 1. Drawing shows the anatomy of PAK transplantation, with bladder drainage and detailed depiction of the aortic patch containing the celiac (black arrow), splenic (sp), and superior mesenteric (*) arteries attached to the recipient common iliac artery. The donor portal vein is attached to the external iliac vein (white arrows). Note the side-to-side anastomosis between the duodenum (D), which is oversewn on both ends, and the bladder. A left iliac fossa renal transplant is also shown.
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For an SPK transplantation, the pancreas is transplanted as described above and the kidney from the same donor is placed in the left iliac fossa of the recipient, with the donor ureter implanted into the bladder. The vascular anastomoses are generally made to the external iliac artery and vein.
Advantages of the systemic-bladder drainage technique include a lower technical complication rate and the ability to monitor graft rejection by following urinary amylase levels. However, the procedure directs venous outflow from the transplanted pancreas away from the liver and into the systemic circulation, resulting in peripheral hyperinsulinemia, which can cause dyslipidemia and accelerate the development of insulin resistance and atherosclerosis (5–7). In addition, exocrine secretions in the urinary bladder can result in recurrent urinary tract infections, cystitis, urethritis, metabolic acidosis and dehydration, hematuria, bladder stones, and graft pancreatitis secondary to reflux. At 1 year after transplantation, 5%–10% of transplant recipients require operations to convert from bladder to enteric drainage (8).
As a result, the portal-enteric drainage technique has become more widespread. From 1998 to 2000, 41%–63% of SPK transplantations were performed with enteric drainage; slightly less than 20% of enteric-drained transplants had portal drainage (1). In this procedure, the head of the pancreas may be placed in the cephalic position with a side-to-side anastomosis of the donor duodenum to a jejunal loop. The pancreatic venous outflow is drained into the portal venous system via the superior mesenteric vein of the recipient (Fig 2).
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Figure 2. Diagram illustrates the portal-enteric technique for pancreatic transplantation. Vascular reconstruction involves connecting a donor iliac arterial Y-graft, composed of the internal and external branches of the donor common iliac artery, to the donor splenic (sp) and superior mesenteric (sm) arteries. The common iliac portion of the Y-graft is then anastomosed to the recipient common or external iliac artery. Venous drainage goes into the superior mesenteric vein (S). Note the donor duodenum (D), which is oversewn at both ends, with a side-to-side anastomosis to the recipient Roux-en-Y loop.
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SPK Transplantation
From January 1, 1996, to July 11, 2000, 84% of pancreatic transplantations performed in the United States were SPK procedures (1). For patients with severe type I diabetes mellitus and end-stage renal disease, SPK transplantation is the preferred treatment (9). It has the highest graft survival rate (84% of cases) compared with the other types of transplantation (73% for PAK; 70% for PTA) (1) and renders patients free of the need for both insulin therapy and dialysis (10–14). In a retrospective study, Smets et al (15) compared the survival rates of two cohorts of diabetic patients with end-stage renal disease treated with either SPK or PTA transplantation. After 10 years, the group that underwent SPK transplantation had significantly improved survival, with 50% lower mortality and reduced morbidity, than those who underwent PTA transplantation (15).
PAK Transplantation
From 1987 to 1993, only 7% of pancreatic transplantations performed were PAK procedures (16); from 1996 to 2000, the percentage increased to 12% (1). Unlike SPK transplantation, in which the renal and pancreatic grafts are from the same donor, the PAK transplants come from different donors. In PAK transplantation, the kidney (usually from a living donor) is transplanted before the cadaveric pancreas and may be placed in the left iliac fossa. PAK transplantation is a good alternative to the SPK procedure, despite having somewhat lower pancreatic graft survival rates. The advantages of PAK transplantation include the ability to use a living donor kidney (and thus obtain higher kidney graft survival rates), expansion of the cadaver kidney donor pool, decreased surgical complications associated with pancreatic transplantation (as a result of shorter operation times and less extensive dissection), and decreased waiting time to transplantation (167 days for PAK vs 244 days for SPK) (17). If a living donor kidney is available for a uremic diabetic patient, PAK transplantation should be considered. However, delaying pancreatic transplantation until after renal transplantation results in a poorer pancreatic graft survival rate and a worse long-term prognosis (18).
PTA Transplantation
PTA is the least commonly performed type of pancreatic transplantation, accounting for just 5% of these procedures (19). However, for compliant nonuremic patients with labile insulin-independent diabetes mellitus and hypoglycemic unawareness, it has proved to be a viable alternative to traditional long-term insulin therapy. Previously, the PTA graft and patient survival rates have been well below those for SPK and PAK transplantations. More recently, however, PTA graft and patient survival rates are approaching those of the other transplantation types. This improvement can be attributed to the increased clinical experience, improved surgical techniques, application of HLA matching, more accurate diagnosis of rejection, use of new immunosuppressant agents, and availability of less toxic agents for prophylaxis and treatment of posttransplantation infections (19).
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Importance of Clinical Parameters in Assessing Graft Dysfunction
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Despite the remarkable improvements made in the first-year graft survival rates for all three types of pancreatic transplantation, the high prevalence of graft loss caused by immunologic rejection and surgical complications continues to be a problem. Of all the transplantations performed from 1996 to 2000, the rejection loss rate was 7%–9% at 1 year (1). From 1998 to 2000, the technical failure rate was 7%–8%, with vascular thrombosis being the main cause (1). Infection, pancreatitis, bleeding, and anastomotic leaks are other sources of transplant failure.
Many pancreatic transplant recipients with graft dysfunction do not present with the classic clinical symptoms of fever, graft tenderness, abdominal pain, ileus, and dysuria. Therefore, routine postoperative monitoring of certain biochemical markers is performed to assess the graft indirectly. For SPK transplantations, rejection usually involves both grafts. Therefore, the serum creatinine level is generally agreed to be the most sensitive marker for rejection (18,20). However, no single biochemical marker (serologic or urinary) has allowed acute pancreatic graft rejection to be distinguished accurately from vascular thrombosis or pancreatitis (21,22). When their levels are abnormally elevated or decreased, these markers (serum glucose, serum amylase, urine amylase, serum anodal trypsinogen, serum pancreas-specific protein, serum lipase, and urine cytology) are used as indicators for further evaluation, including noninvasive monitoring (sonography) or biopsy under sonographic guidance.
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Role of Sonography
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Imaging of the pancreas has a definite, albeit limited, role in that findings are often subtle or nonspecific, such as in the evaluation for graft rejection and anastomotic leaks. Sonography is useful for visualization of the pancreatic allograft and for the detection of peripancreatic fluid collections and the presence or absence of blood flow (23). However, sonographic evaluation of the transplanted pancreas is more difficult and complex than the assessment of the transplanted kidney. The advantages afforded by color Doppler techniques are frequently hindered by technical difficulties and the often nonspecific nature of color Doppler imaging findings. At gray-scale sonography, the parenchyma of a normal pancreatic transplant appears as homogeneous soft tissue surrounded by more echogenic soft tissue that represents omental and peritoneal fat (Figs 3, 4). Although locating the iliac vessels and splenic artery and vein with color or power Doppler imaging can aid in locating the pancreas, its direct visualization is often difficult. Because the graft is placed intraperitoneally, overlying bowel gas often obscures the pancreas. Often, the fluid within the duodenum is insufficient to permit adequate visualization. This problem is particularly significant in cases in which the head of the pancreas is positioned more cephalad in the peritoneal cavity (as is the case for enteric and portal venous drainage). In addition, the graft lacks an investing capsule, which often renders its borders indistinct. Without the presence of the adjacent liver to be used as an acoustic window and a basis for comparison, the ability to determine changes in echogenicity of the transplanted pancreas is limited (Fig 5a). The presence of fluid surrounding the transplant markedly increases its conspicuity (Fig 5b). Color and power flow sonographysignificantly enhance the ability to visualize the pancreatic graft and its surrounding and internal vascularity (Fig 6).
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Figure 4. Gray-scale sonogram depicts the anatomy of the duodenopancreatic graft and its relationship to the pancreas. BL = bladder, D = duodenum, P = pancreas, with cursors delineating the pancreatic head.
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Figure 5a. (a) Gray-scale sonogram of a PTA transplant reveals a heterogeneous appearance of the pancreatic parenchyma (arrows). Increased echogenicity of the pancreatic parenchyma renders the transplant isoechoic relative to the adjacent peripancreatic soft tissues. Because the pancreas lacks a defining capsule, the borders of the graft become indistinct, particularly in cases of acute graft rejection and pancreatitis. (b) Gray-scale sonogram of the pancreatic transplant in another patient demonstrates that sonographic delineation of the transplant is superior when it is outlined by fluid.
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Figure 5b. (a) Gray-scale sonogram of a PTA transplant reveals a heterogeneous appearance of the pancreatic parenchyma (arrows). Increased echogenicity of the pancreatic parenchyma renders the transplant isoechoic relative to the adjacent peripancreatic soft tissues. Because the pancreas lacks a defining capsule, the borders of the graft become indistinct, particularly in cases of acute graft rejection and pancreatitis. (b) Gray-scale sonogram of the pancreatic transplant in another patient demonstrates that sonographic delineation of the transplant is superior when it is outlined by fluid.
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Figure 6a. (a) Color flow sonogram demonstrates a portion of the pancreatic transplant (P) and the patent splenic artery and vein, seen on its undersurface. (b) Power flow image of another patient demonstrates normal intraparenchymal flow within the pancreatic transplant.
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Figure 6b. (a) Color flow sonogram demonstrates a portion of the pancreatic transplant (P) and the patent splenic artery and vein, seen on its undersurface. (b) Power flow image of another patient demonstrates normal intraparenchymal flow within the pancreatic transplant.
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Fluid collections are easily detected at sonography; however, the findings are usually nonspecific. Hematomas, abscesses, urinary leaks, ascites (Fig 7), and anastomotic leaks (Fig 8) can appear as anechoic, hypoechoic, or complex, debris-filled, irregular collections (18). Infection (in addition to major vascular insults) may result in necrosis of the transplant and necessitate its surgical removal. Foci of air associated with pancreatic necrosis (Fig 9) or emphysematous pancreatitis may be detected sonographically and confirmed with CT.
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Figure 7. Ascites in a patient who underwent SPK transplantation. Power flow image of the pancreatic transplant reveals a large anechoic fluid collection (FL) within the peritoneal cavity. An exocrine leak can precipitate ascites. The common iliac artery (a) and the Y-graft (arrow) are also shown.
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Figure 8. Duodenovesicular anastomotic leak in a patient who underwent SPK transplantation. Gray-scale sonogram reveals a small amount of anechoic fluid (cursors) anterior to the pancreatic transplant (arrows).
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Figure 9a. Pancreatic necrosis in a patient who recently underwent pancreatic transplantation and who presented with fever, leukocytosis, and severe right lower quadrant tenderness. (a) Gray-scale sonogram shows multiple echogenic foci (arrow) within the substance of the pancreatic transplant, findings compatible with foci of intraparenchymal air. (b) Subsequent CT scan obtained later that day helps confirm the presence of intrapancreatic air (arrow). At surgery, the necrotic transplant was draped with purulent material.
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Figure 9b. Pancreatic necrosis in a patient who recently underwent pancreatic transplantation and who presented with fever, leukocytosis, and severe right lower quadrant tenderness. (a) Gray-scale sonogram shows multiple echogenic foci (arrow) within the substance of the pancreatic transplant, findings compatible with foci of intraparenchymal air. (b) Subsequent CT scan obtained later that day helps confirm the presence of intrapancreatic air (arrow). At surgery, the necrotic transplant was draped with purulent material.
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Although acute rejection is a significant postoperative complication, sonography has a limited role in the identification of acute graft rejection, as its sensitivity is quite variable, ranging from 13% to 82% (24–27). Gray-scale sonography may demonstrate gland enlargement with focal or diffuse areas of decreased echogenicity without pancreatic duct dilatation (24,25) (Fig 10). However, these findings are also seen in cases of vascular compromise and pancreatitis (Fig 11). CT may sometimes aid in differentiating rejection from acute pancreatitis (Fig 12).
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Figure 10. Acute graft rejection in a patient with a PTA transplant. Power flow image shows nonspecific heterogeneity of the pancreatic graft parenchyma and graft swelling. Changes within the parenchyma are subtle. A small amount of peripancreatic fluid is seen anterior to the graft (arrow). Biopsy helped confirm acute rejection. Similar sonographic findings may be seen with graft pancreatitis.
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Figure 11. Graft pancreatitis. Gray-scale sonogram reveals nonspecific enlargement and heterogeneity of the head of the transplanted pancreas (arrows). The patient’s serum amylase and lipase levels were markedly elevated. Findings from subsequent exploratory laparotomy confirmed the clinical diagnosis of pancreatitis.
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Figure 12a. Pancreatitis in another patient with an amylase level exceeding 900. (a) Gray-scale sonogram reveals a hypoechoic pancreas (arrows) with fluid surrounding the transplant. (b) CT scan obtained the same day better delineates the extent of the large peripancreatic fluid collection. The mildly enhancing pancreatic transplant (P) is difficult to discern.
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Figure 12b. Pancreatitis in another patient with an amylase level exceeding 900. (a) Gray-scale sonogram reveals a hypoechoic pancreas (arrows) with fluid surrounding the transplant. (b) CT scan obtained the same day better delineates the extent of the large peripancreatic fluid collection. The mildly enhancing pancreatic transplant (P) is difficult to discern.
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Color Doppler flow imaging and power Doppler imaging have greatly enhanced our ability to evaluate the intra- and extraparenchymal vasculature of the pancreatic graft, especially when CT cannot be performed with iodinated contrast material because of a patient’s high serum creatinine levels (Figs 6, 13). Power Doppler imaging easily reveals the Y-graft vascular anastomosis at the vascular pedicle (Fig 7). Often, the splenic artery and vein can be readily identified (Fig 6). These structures end blindly and thus have an increased possibility of becoming thrombosed. Consequently, Doppler sonography has been particularly important in detecting vascular complications such as thrombosis, anastomotic strictures, and pseudoaneurysm formation (Fig 14) (28). Thrombosis is demonstrated by the absence of perceptible arterial or venous tracings as well as by direct visualization of intraluminal echogenic material that occludes blood flow (29). It is important that the decrease or absence of color flow be confirmed with spectral Doppler analysis before a diagnosis of thrombosis is made. High velocity or turbulence at the arterial or venous anastomoses suggests strictures (30), and arterial flow within a perianastomotic fluid collection, the presence of swirling blood flow at color flow sonography, and the classic "to-and-fro" spectral Doppler pattern indicate a complicating pseudoaneurysm (28).
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Figure 13. Normal vascularity. Power flow sonogram of the pancreatic graft shows normal vascularity. Note how easy it is to discern the pancreatic transplant when it is surrounded by fluid.
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Figure 14a. Pseudoaneurysm. (a) Color Doppler flow image demonstrates the classic swirling pattern in a large pseudoaneurysm adjacent to a pancreatic transplant. The supplying artery is the donor splenic artery (red) with the splenic vein (blue) adjacent to it. (b) Three-dimensional CT angiogram depicts the pseudoaneurysm. The white curved line is the duodenal stump suture line (arrow). The kidney transplant (K) is located posterior to it, whereas the pancreatic transplant (P) is seen as the faint green structure inferior to the pseudoaneurysm. (Case courtesy of Myron A. Pozniak, University of Wisconsin Hospital, Madison, Wis.)
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Figure 14b. Pseudoaneurysm. (a) Color Doppler flow image demonstrates the classic swirling pattern in a large pseudoaneurysm adjacent to a pancreatic transplant. The supplying artery is the donor splenic artery (red) with the splenic vein (blue) adjacent to it. (b) Three-dimensional CT angiogram depicts the pseudoaneurysm. The white curved line is the duodenal stump suture line (arrow). The kidney transplant (K) is located posterior to it, whereas the pancreatic transplant (P) is seen as the faint green structure inferior to the pseudoaneurysm. (Case courtesy of Myron A. Pozniak, University of Wisconsin Hospital, Madison, Wis.)
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The use of resistive indexes (resistive index = peak systolic velocity - end diastolic velocity / systolic velocity) has been well established for predicting acute rejection of renal grafts. However, because the pancreatic graft lacks a capsule, an edematous pancreatic graft may not possess adequate intraparenchymal pressure to produce a reliable measurement of vascular resistance (31) (Fig 15). Unlike renal transplants for which specific resistive index values have been proved to be accurate predictors of acute rejection, no reliable resistive index measurement has been established for at-risk pancreatic grafts. Some studies have demonstrated elevated pancreatic reactive indexes during episodes of acute rejection (32–34), although others have shown no correlation (2, 31,35).
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Figure 15. Normal resistive index measurement. Duplex color Doppler flow imaging is useful in assessing the intraparenchymal arterial pressures as an indirect measure to detect complications such as vascular thrombosis, acute graft rejection, and pancreatitis. The measurement can be obtained from the intraparenchymal arterial vasculature (head, body, tail), or the extraparenchymal arterial vasculature (Y-graft). However, these measurements have not proved to be sensitive or specific in diagnosing certain complications.
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Percutaneous biopsy performed with sonographic guidance provides a quick, effective, and low-risk method for evaluating the graft when the biochemical markers and sonographic findings suggest an abnormality (36). With use of grayscale sonography, an acoustic window to the graft is obtained. Power Doppler imaging is used to reveal the vascular structures. An 18-gauge core biopsy needle is inserted through the peritoneum and directly into the pancreas under sonographic guidance (Fig 16). Obtaining two to three core samples from the pancreatic body or tail is sufficient to make a histologic diagnosis (Fig 17). A sonogram is obtained after biopsy to search for any immediate biopsy-related complications.
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Figure 17a. Acute graft rejection in a patient with a PTA transplant and subtle sonographic findings who underwent percutaneous biopsy. (a) Photomicrograph (original magnification, x100; hematoxylin-eosin stain) of a histologic specimen shows the focus of acinar inflammation and ductal inflammatory destruction by lymphocytes, characteristic of rejection (arrow). (b) Photomicrograph (original magnification, x100; hematoxylin-eosin stain) of another histologic specimen shows destruction of acinar cells by lymphocytes (arrow). The degree of infiltration is compatible with grade 4 moderate rejection.
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Figure 17b. Acute graft rejection in a patient with a PTA transplant and subtle sonographic findings who underwent percutaneous biopsy. (a) Photomicrograph (original magnification, x100; hematoxylin-eosin stain) of a histologic specimen shows the focus of acinar inflammation and ductal inflammatory destruction by lymphocytes, characteristic of rejection (arrow). (b) Photomicrograph (original magnification, x100; hematoxylin-eosin stain) of another histologic specimen shows destruction of acinar cells by lymphocytes (arrow). The degree of infiltration is compatible with grade 4 moderate rejection.
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In prior studies, percutaneous biopsy demonstrated a success rate of 88% (37,38). With experience, the success rate has been reported to increase to 95% (31). Complications associated with biopsy such as fistula formation, bleeding, and infection have not proved to be significant, occurring in approximately 2% of cases (37,38). Advantages of percutaneous biopsy are its relative noninvasiveness and the ability to sample a large portion of the pancreatic transplant. However, poor visualization of the transplant because of adjacent bowel, patient body habitus, or a small transplant can result in technical failure. In our experience, overlying bowel is rarely a limiting factor. Sonography may be repeated periodically until an adequate biopsy window becomes available.
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Conclusions
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Sonography is a noninvasive, widely accessible, and relatively inexpensive means for evaluating the pancreatic transplant. Color and power Doppler imaging offer valuable information regarding the regional vasculature and potential vascular complications. Because gray-scale sonographic findings alone are often nonspecific, clinical information must be considered when interpreting the sonographic findings. When used in conjunction with serologic and urinary markers, the findings from sonography can help direct management options or suggest the need for further examination including CT, MR imaging, cystography, paracentesis, scintigraphy, or sonographic-guided percutaneous biopsy. Histopathologic diagnosis remains the standard, particularly in cases of suspected acute graft rejection.
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Footnotes
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Abbreviations: PAK = pancreas after kidney,
PTA = pancreas transplant alone,
SPK = simultaneous pancreas-kidney
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References
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Abstract
LEARNING OBJECTIVES FOR TEST...
