Contrast-enhanced MR Angiography for Evaluation of Vascular Complications of the Pancreatic Transplant

doi:10.1148/rg.253045094

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Contrast-enhanced MR Angiography for Evaluation of Vascular Complications of the Pancreatic Transplant¹

Nora Dobos, MD, David A. Roberts, MD, PhD, Erik K. Insko, MD, PhD², Evan S. Siegelman, MD, Ali Naji, MD, PhD and James F. Markmann, MD, PhD

¹ From the Department of Radiology, MRI Learning Center, 1 Founders, Hospital of the University of Pennsylvania, Philadelphia (N.D., E.K.I., E.S.S., A.N., J.F.M.); and the Kennedy Health System, Cherry Hill, NJ (D.A.R.). Recipient of a Certificate of Merit award for an education exhibit at the 2003 RSNA Scientific Assembly. Received April 28, 2004; revision requested July 12 and received August 11; accepted August 18. All authors have no financial relationships to disclose.

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Figure 1. Drawing illustrates a pancreatic transplant after harvesting. a = portal vein stump, b = splenic vein stump, c = superior mesenteric vein (SMV) stump, d = splenic artery origin, e = splenic artery stump, f = SMA origin, g = SMA stump, h = inferior pancreaticoduodenal artery, i = inferior pancreaticoduodenal vein, j = dorsal pancreatic artery, k = dorsal pancreatic veins, l = duodenum.

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Figure 2. Drawing illustrates typical arterial anastomoses of a pancreatic transplant. a = Y graft donor CIA, b = Y graft donor external iliac artery, c = Y graft donor internal iliac artery, d = recipient CIA or external iliac artery.

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Figure 3. Drawing illustrates a pancreatic transplant with systemic venous drainage. a = donor portal vein, b = recipient common iliac vein, external iliac vein, or IVC.

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Figure 4. Drawing illustrates portal venous drainage in a pancreatic transplant. a = recipient SMV, b = donor portal vein.

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Figure 5. Coronal contrast-enhanced 3D venous phase MR angiogram shows normal arterial supply and systemic venous drainage, with the venous anastomosis to the IVC and the pancreas situated in the right lower quadrant and pelvis. The donor SMV (arrowhead), splenic vein (small arrow), and splenic artery (large arrow) are all well demonstrated.

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Figure 6. Contrast-enhanced 3D venous phase MR angiogram shows normal portal venous drainage, with the venous anastomosis (arrow) to the recipient SMV just inferior to the portosplenic confluence.

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Figure 7. Coronal contrast-enhanced 3D arterial phase MR angiogram shows normal arterial anastomoses, with the arterial anastomosis of the Y graft to the recipient right CIA (arrow). The donor splenic artery (arrowhead) is well shown along the tail of the pancreatic transplant, thereby demonstrating the orientation of the pancreas.

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Figure 8a. Arterial stump thrombosis. (a) Contrast-enhanced MR angiogram shows normal pancreatic graft enhancement. The venous anastomosis is to the right common iliac vein (not shown), and the pancreatic head is located inferiorly. (b) Contrast-enhanced MR angiogram shows a thrombus in the SMA stump (arrow). The thrombus is distal to any perforating arteries feeding the pancreatic transplant and did not require therapy.

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Figure 8b. Arterial stump thrombosis. (a) Contrast-enhanced MR angiogram shows normal pancreatic graft enhancement. The venous anastomosis is to the right common iliac vein (not shown), and the pancreatic head is located inferiorly. (b) Contrast-enhanced MR angiogram shows a thrombus in the SMA stump (arrow). The thrombus is distal to any perforating arteries feeding the pancreatic transplant and did not require therapy.

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Figure 9a. Arterial stump thrombus in a graft with SMV venous drainage. (a) Precontrast T1-weighted MR angiogram clearly depicts the arterial branches, with the SMA branch (arrowhead) supplying the superiorly positioned pancreatic head and the splenic artery branch (arrow) feeding the inferiorly positioned pancreatic tail. (b) Precontrast T1-weighted MR angiogram shows a high-signal-intensity thrombus (arrow) within the distal SMA stump in the right upper quadrant just inferior to the edge of the liver (arrowhead). High-signal-intensity clot secondary to methemoglobin can potentially mimic normal flow at contrast-enhanced MR angiography. Thus, both imaging technique and the interpretation of findings at precontrast MR angiography are important to avoid this potential pitfall of false-positive vessel patency (8).

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Figure 9b. Arterial stump thrombus in a graft with SMV venous drainage. (a) Precontrast T1-weighted MR angiogram clearly depicts the arterial branches, with the SMA branch (arrowhead) supplying the superiorly positioned pancreatic head and the splenic artery branch (arrow) feeding the inferiorly positioned pancreatic tail. (b) Precontrast T1-weighted MR angiogram shows a high-signal-intensity thrombus (arrow) within the distal SMA stump in the right upper quadrant just inferior to the edge of the liver (arrowhead). High-signal-intensity clot secondary to methemoglobin can potentially mimic normal flow at contrast-enhanced MR angiography. Thus, both imaging technique and the interpretation of findings at precontrast MR angiography are important to avoid this potential pitfall of false-positive vessel patency (8).

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Figure 10a. Splenic vein thrombosis. (a) Coronal 3D arterial phase MR angiogram shows the arterial anastomosis of the Y graft to the recipient right CIA. The donor SMA anastomosis is present superiorly in the pancreatic transplant, which is oriented with the head located superiorly and the tail inferiorly as the venous anastomosis is to the SMV. (b) Coronal 3D MR angiogram shows thrombosis of the donor splenic vein branch draining the tail of the pancreas (arrow). The tail was hypoperfused as a result of the splenic vein thrombosis. (c) Coronal oblique MR angiogram better delineates the long segment of thrombosis within the donor splenic vein (arrow).

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Figure 10b. Splenic vein thrombosis. (a) Coronal 3D arterial phase MR angiogram shows the arterial anastomosis of the Y graft to the recipient right CIA. The donor SMA anastomosis is present superiorly in the pancreatic transplant, which is oriented with the head located superiorly and the tail inferiorly as the venous anastomosis is to the SMV. (b) Coronal 3D MR angiogram shows thrombosis of the donor splenic vein branch draining the tail of the pancreas (arrow). The tail was hypoperfused as a result of the splenic vein thrombosis. (c) Coronal oblique MR angiogram better delineates the long segment of thrombosis within the donor splenic vein (arrow).

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Figure 10c. Splenic vein thrombosis. (a) Coronal 3D arterial phase MR angiogram shows the arterial anastomosis of the Y graft to the recipient right CIA. The donor SMA anastomosis is present superiorly in the pancreatic transplant, which is oriented with the head located superiorly and the tail inferiorly as the venous anastomosis is to the SMV. (b) Coronal 3D MR angiogram shows thrombosis of the donor splenic vein branch draining the tail of the pancreas (arrow). The tail was hypoperfused as a result of the splenic vein thrombosis. (c) Coronal oblique MR angiogram better delineates the long segment of thrombosis within the donor splenic vein (arrow).

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Figure 11a. Propagation of venous stump thrombus. (a) Coronal 3D venous phase MR angiogram shows a pancreatic graft with a venous anastomosis to the SMV (not shown). The SMV is thrombosed to the portosplenic confluence of the graft (arrow). (b) Routine axial two-dimensional postcontrast T1-weighted MR image shows a portion of a thrombosed arterial stump (arrow). Low-signal-intensity thrombus on T1-weighted images is often difficult to visualize on maximum-intensity-projection reformatted images.

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Figure 11b. Propagation of venous stump thrombus. (a) Coronal 3D venous phase MR angiogram shows a pancreatic graft with a venous anastomosis to the SMV (not shown). The SMV is thrombosed to the portosplenic confluence of the graft (arrow). (b) Routine axial two-dimensional postcontrast T1-weighted MR image shows a portion of a thrombosed arterial stump (arrow). Low-signal-intensity thrombus on T1-weighted images is often difficult to visualize on maximum-intensity-projection reformatted images.

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Figure 12. Consequences of complete venous thrombosis. Three-dimensional arterial phase MR angiogram shows lack of perfusion of a pancreatic transplant due to complete venous thrombosis extending to the anastomosis with the right common iliac vein (not shown). Secondary graft infarction required surgical removal (outlined). Note the duplicated left-sided IVC (arrow) and the left pelvic kidney transplant (arrowhead).

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Figure 13a. Suspected acute rejection in a patient who presented 6 days following transplantation with pain over the graft. (a) Initial coronal 3D MR angiogram shows a widely patent splenic artery branch of the donor pancreas. The venous anastomosis is to the right common iliac vein (not shown), and the pancreatic head is located inferiorly with the tail oriented more superiorly. Arrow indicates the arterial anastomosis of the Y graft to the donor splenic artery. The patient was treated expectantly, only to return 5 days later with persistent pain and an elevated serum glucose level. (b) Repeat coronal 3D MR angiogram demonstrates patency of all the vessels (donor splenic artery segment shown) but a dramatic decrease in the caliber of the arteries distal to the anastomosis, a finding that was thought to be due to acute rejection. No biopsy was performed. The patient was treated expectantly, with subsequent normalization of the serum glucose level and resolution of symptoms.

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Figure 13b. Suspected acute rejection in a patient who presented 6 days following transplantation with pain over the graft. (a) Initial coronal 3D MR angiogram shows a widely patent splenic artery branch of the donor pancreas. The venous anastomosis is to the right common iliac vein (not shown), and the pancreatic head is located inferiorly with the tail oriented more superiorly. Arrow indicates the arterial anastomosis of the Y graft to the donor splenic artery. The patient was treated expectantly, only to return 5 days later with persistent pain and an elevated serum glucose level. (b) Repeat coronal 3D MR angiogram demonstrates patency of all the vessels (donor splenic artery segment shown) but a dramatic decrease in the caliber of the arteries distal to the anastomosis, a finding that was thought to be due to acute rejection. No biopsy was performed. The patient was treated expectantly, with subsequent normalization of the serum glucose level and resolution of symptoms.

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Figure 14. Susceptibility artifact mimicking stenosis. Coronal 3D MR angiogram shows loss of signal near the bifurcation of the arterial Y graft. This signal loss is due to susceptibility artifact from an adjacent surgical clip and not to any pathologic condition at the anastomosis.

Contrast-enhanced MR Angiography for Evaluation of Vascular Complications of the Pancreatic Transplant1

Contrast-enhanced MR Angiography for Evaluation of Vascular Complications of the Pancreatic Transplant¹