Evaluation of pancreatic allografts with sonography.

OBJECTIVES: The purposes of this study were to develop a protocol for evaluating pancreas allografts, to describe a method for successfully studying pancreatic transplants, and to determine whether the resistive index (RI) of the splenic artery is a useful differentiator between complications. METHODS: We retrospectively analyzed clinical, surgical, procedural, and radiologic reports in 51 consecutive patients undergoing 182 sonographic examinations during a 4.5-year period. Complications included splenic vein thrombosis, rejection, and pancreatitis. We obtained RIs in normal and complication groups and performed mixed model regression methods and receiver operating characteristic analysis. RESULTS: The mean RI ± SD for normal transplants was 0.65 ± 0.09; for splenic vein thrombosis, 0.76 ± 0.09; after resolution of splenic vein thrombosis, 0.73 ± 0.09; during rejection, 0.94 ± 0.09; after successful treatment of rejection, 0.74 ± 0.09; for pancreatitis, 0.83 ± 0.09; and for fluid collections, 0.66 ± 0.09. There was a statistically significant difference (P < .05) between normal transplants and splenic vein thrombosis (P = .0003), rejection (P < .0001), and pancreatitis (P = .04). A significant difference was also seen between rejection and successful treatment thereof (P < .0001). CONCLUSIONS: We developed a protocol that allowed us to successfully evaluate 96% of the pancreatic allografts studied. Furthermore, our data show that the RI can be used as a therapeutic guide. When the RI is less than 0.65, the risk of vascular abnormalities is very low; however, fluid collections may be present. When greater than 0.75, splenic vein thrombosis, pancreatitis, or rejection should be suspected. When greater than 0.9, rejection must be seriously considered.

Imaging of miscellaneous pancreatic pathology (trauma, transplant, infections, and deposition).

In this article's coverage of miscellaneous pancreatic topics, a brief review of pancreatic trauma; pancreatic transplantation; rare infections, such as tuberculosis; deposition disorders, including fatty replacement and hemochromatosis; cystic fibrosis; and others are discussed with pertinent case examples.

Imaging after pancreatic surgery.

Pancreatic surgery, until the Whipple era in the early 1900s, was once regarded as calamitous by most surgeons. With advances in surgical techniques, operative mortality has been greatly reduced, although morbidity remains a significant problem. Knowledge of the surgical options for treatment of pancreatic neoplastic and inflammatory disease is important for the practicing radiologist, to anticipate and identify complications commonly sought and well depicted with imaging.

Multi-detector CT/CT angiogram assessment of acute pancreatic graft dysfunction.

Simultaneous pancreatic-kidney transplantation is the definitive treatment for patients with type 1 diabetes mellitus and renal failure. Pancreatic graft failure is an important postoperative complication and most commonly occurs as a result of pancreatitis, graft thrombosis or rejection. Distinguishing between these causes is necessary to determine timely, appropriate management and thereby potentially minimising graft loss. Multi-detector CT imaging may be used to identify the cause of pancreatic graft dysfunction when renal function is not markedly impaired.

Imaging of pancreas transplants: postoperative findings with clinical correlation.

Pancreas transplantation has become more commonplace over the past several decades. Consequently, the radiological evaluation of patients with such transplants has also become more common. Radiologists must therefore be familiar with the normal imaging appearances of pancreas transplant grafts as well as a wide variety of transplant-related complications. In this article, we review the cross-sectional imaging appearances of normal pancreas transplant grafts as well as present representative examples of complications associated with the procedure.

Pancreas transplants.

Cadaveric, whole pancreas transplantation has proved an effective therapy in the treatment of long-standing type 1 diabetes mellitus and is capable of achieving an insulin-independent eugyclaemic state. As a result, this procedure is being increasingly performed. However, the surgical procedure is complex and unfamiliar to many radiologists. Imaging with computed tomography (CT) and magnetic resonance imaging (MRI) gives excellent results and can be used confidently to diagnose vascular, enteric, and immune-mediated complications. We present a review of the normal post-transplantation appearance and the features of early and late complications.

Enteric drainage pancreatic transplantation.

Enteric drainage is currently the preferred method of pancreatic transplantation. This technique results in long-term good control of diabetes. In this report we discuss the postoperative radiologic anatomy and complications.

Pancreatic transplants: noninvasive evaluation with secretin-augmented mr pancreatography and MR perfusion measurements--preliminary results.

Feasibility of secretin-augmented magnetic resonance (MR) pancreatography and dynamic contrast material-enhanced MR measurements for evaluation of functional status of pancreatic allografts was determined by quantifying the excretion and perfusion of the grafts. Ten patients were included prospectively before pancreatic transplantation. Dynamic T2-weighted sequences after secretin stimulation and dynamic contrast-enhanced T1-weighted gradient-echo sequences were performed. Area under the curve and maximum signal intensity-to-time ratio were determined in selected regions of interest. Biochemical parameters, Doppler ultrasonography, and/or surgery were standards for final diagnosis. Patients with normal outcome (n = 7) produced 236 mL +/- 104 (standard deviation) of pancreatic juice, and patients with dysfunctional grafts (n = 3) produced 42 mL +/- 25. Area under the curve and maximum signal intensity-to-time ratio provided thresholds of 0.5 and 0.3, respectively, for distinction between functional and dysfunctional grafts. Secretin-augmented MR pancreatography combined with MR perfusion measurements may aid in differentiation between patients with and those without graft dysfunction.

[Pancreas transplantation: multislice computed tomography follow-up].

PURPOSE: Solitary pancreas or combined kidney-pancreas transplantation is currently the only therapeutic procedure for complete resolution of diabetes mellitus type I. The aim of the present study is to investigate the role of multislice computed tomography (MSCT) in the follow-up of patients subjected to solitary pancreas or combined kidney-pancreas transplantation. MATERIALS AND METHODS: Sixteen patients who had undergone solitary pancreas (n=8) or combined kidney-pancreas (n=8) transplantation, with systemic-bladder (n=6) or portal-enteric (n=10) pancreatic drainage were evaluated with MSCT (Light Speed Plus, GE Medical System). In solitary pancreas follow-up the MSCT study included arterial and portal phases; in combined kidney-pancreas transplanted patients the urographic phase was included. The acquisition was performed with 1.25 mm collimation, 0.6 mm reconstruction interval and a pitch of 6. An MSCT scan of the thorax was included in patients suspected of having lung complications. RESULTS: In all cases MSCT allowed identification of the surgical technique performed, evaluation of the transplanted pancreas, and assessment of complications, if present. The following major complications were identified: thrombosis or stenosis of the arterial graft, pancreatic infarction, ectasia of the common iliac artery and arterial graft, dehiscence of the duodenocystostomy, infected abdominal collections, pulmonary infections. CONCLUSIONS: MSCT is able to detect complications arising in the transplanted organs and those related to immunosuppressive therapy, and confirms its usefulness in the follow-up of solitary pancreas or combined kidney-pancreas transplanted patients.

Pancreatic ultrasonography.

Pancreatic abnormalities usually are detected on US when it is used for screening patients with abdominal pain and for assessment of the gallbladder and bile ducts. Pancreatic visualization is limited by bowel gas, but with experienced sonographers and newer techniques, including harmonic imaging and oral contrast US, diagnosis of pancreatic abnormalities has significantly improved compared with earlier reports. Appropriate initial diagnosis by US can tailor further investigation, and US-guided biopsy may establish definitive diagnosis.

Pancreatic transplantation using portal venous and enteric drainage: the postoperative appearance of a new surgical procedure.

PURPOSE: To review the normal radiologic appearance of pancreatic transplants that use portal venous and enteric drainage, and to review the appearance of a variety of postoperative complications. METHOD: We retrospectively reviewed the computed tomographic (CT) scans, magnetic resonance (MR) images, and ultrasounds of patients who had undergone pancreatic transplantation using portal venous and enteric drainage. RESULTS: At CT, the normal pancreatic transplant appears as a heterogeneous mass composed of pancreatic parenchyma, vessels, and omental wrap. On MR imaging, a normal transplant demonstrates intermediate signal intensity on T1- and T2-weighted sequences. Sonographic evaluation of a normal transplant reveals a hypoechoic gland that contains readily detectable low-resistance arterial and venous Doppler waveforms. Acute postoperative complications include acute rejection, which has a nonspecific radiologic appearance, and transplant pancreatitis, which is often manifested on CT by stranding of the peritransplant fat. Chronic postoperative complications include small bowel obstructions, graft pancreatitis secondary to obstruction of the Roux loop, and chronic rejection. CONCLUSION: Knowledge of the radiologic appearance of the normal pancreatic transplant is required before transplant-related complications can be detected.

Imaging of pancreatic transplantation using portal venous and enteric exocrine drainage.

OBJECTIVE: We describe the normal radiologic appearance of pancreatic allografts transplanted using portal venous drainage with enteric drainage of exocrine secretions. We also describe the radiologic appearance of postsurgical complications. MATERIALS AND METHODS: Of 56 patients who received pancreatic transplants using the portal-enteric technique, 24 patients subsequently required radiologic examination for suspected complications involving the pancreatic allograft. Twenty-three patients underwent CT scanning; a total of 58 CT scans were obtained. Nine abdominal sonograms were obtained in five patients, and one patient underwent angiography. The radiologic appearance of each transplant and the complications were analyzed retrospectively and correlated with the clinical course. RESULTS: The most common indications for CT scanning were fever, elevated levels of serum amylase, and evaluation or follow-up of fluid collections. CT showed the normal and abnormal anatomy of the allograft. Abnormal findings seen in the 58 CT scans included fat stranding (30 scans), ascites (21 scans), peripancreatic fluid or pseudocyst (13 scans), and heterogeneity of the allograft (five scans). One patient had pancreatic infarction with pneumatosis and pneumoperitoneum. The allograft was obscured by bowel gas on three sonograms. Four sonograms showed no abnormalities (one Doppler sonogram showed the arterial supply and venous drainage), and one sonogram showed a pseudocyst. In the one patient who underwent angiography, imaging showed no arterial blood flow to the transplant. CONCLUSION: Pancreatic transplantation with portal venous drainage and enteric drainage of exocrine secretions and the complications of such transplantation were revealed with CT, sonography, and angiography. Knowledge of normal anatomic configuration will allow proper interpretation of normal and abnormal findings.

Venous thrombosis of pancreatic transplants: diagnosis by duplex sonography.

OBJECTIVE: Our objective was to determine whether elevated pancreatic transplant arterial resistive index (RI) and absence of venous flow correlate with pancreatic transplant venous thrombosis. MATERIALS AND METHODS: Thirteen episodes of surgically documented pancreatic venous thrombosis occurred in 175 pancreases that had been transplanted over a 3-year period. Duplex sonography was performed before surgical exploration in 11 cases. We retrospectively reviewed these 11 sonograms to determine whether blood was flowing in the veins and arteries of the graft. The RI was calculated from all pancreatic artery waveforms. We compared these arterial RIs and the presence or absence of venous flow with those of pancreatic grafts without venous thrombosis to determine sensitivity and specificity. RESULTS: In the venous thrombosis group, thrombosis occurred within 12 days of transplantation (mean, 3.5 days) in all 11 cases. Six cases of thrombosis (55%) occurred within 1 day. Arterial flow was detected within the graft in nine cases (82%) and in the stump of the donor artery between the graft and the recipient iliac artery in the two remaining cases. Antegrade diastolic flow was absent in all arterial tracings. Diastolic flow reversal was present in seven (78%) of nine grafts with detectable intrapancreatic arterial flow. Arterial RIs ranged from 1.00 to 2.00 (mean +/- SD, 1.27 +/- 0.29). Intrapancreatic venous flow was absent in all 11 cases. In the control group (43 examinations in 34 patients) RIs ranged from 0.46 to 1.29 (mean +/- SD, 0.72 +/- 0.18). Two of 43 arterial tracings had diastolic flow reversal (RI > 1.0). Venous flow was present in all examinations in the control group. A statistically significant difference existed between the RIs in the thrombosis group and the RIs in the control group (p = .0001). CONCLUSION: Reversal of diastolic flow in pancreatic transplant arteries is highly specific for detection of graft venous thrombosis during the first 12 days after transplantation. Our findings suggest that an RI greater than or equal to 1.00 and absence of venous flow, in combination, are highly sensitive and specific for the diagnosis of pancreatic graft venous thrombosis.

En bloc pancreas and kidney transplantation in a patient with limited vascular access.

We report a successful en bloc pancreas and kidney transplantation on a type I diabetic patient with advanced peripheral arterial calcific disease, who had frequent life-threatening episodes of hypoglycemia. The en bloc double organ, created by joining the graft renal artery to the arterial Y graft of the pancreas, was implanted to the proximal left common iliac artery, which was the only site available for an arterial anastomosis. Under appropriate circumstances, this procedure would be an option for potential combined pancreas-kidney transplant recipients with severe calcific arterial disease.

Correlation of the arterial resistive index in pancreas transplants of patients with transplant rejection.

OBJECTIVE: This study was undertaken to determine whether arterial resistive indexes (RIs) in pancreas transplants correlate with biopsy-proven transplant rejection. MATERIALS AND METHODS: We retrospectively reviewed arterial RIs in pancreas transplants for all patients who underwent Doppler sonography within 1 week before transcystoscopic or percutaneous biopsy of pancreas transplants. RIs were correlated with type and degree of rejection in the 20 transplants for which biopsies provided sufficient tissue for diagnosis. Three patients were subsequently eliminated from the study because of significant intervening therapy between sonography and biopsy. RESULTS: The nine transplants with no evidence of rejection had a mean arterial RI of 0.64 (range, 0.49-0.80). The six transplants with acute mild or moderate rejection had a mean RI of 0.67 (range, 0.56-0.73). The two transplants with acute severe rejection had a mean RI of 0.85 (range, 0.80-0.90). We found no statistically significant difference between arterial RIs in pancreas transplants of patients with acute mild or acute moderate rejection and those with no evidence of rejection. CONCLUSION: Arterial RIs of pancreas transplants do not differentiate between acute mild or acute moderate rejection and absence of rejection. The higher mean value of arterial RIs in pancreas transplants with acute severe rejection suggests that elevated arterial RIs are sensitive, but not specific, for revealing acute severe rejection of pancreas transplants. However, our study data are limited, and a larger sample size is necessary to draw statistically significant conclusions.