Current Clinical Concerns in CT: Results : Protocols
CT Cholangiography
1. I want to rule out pancreatic divisum in a patient for whom MRCP was nondiagnostic. Do you think a standard CT cholangiogram protocol on a 16 slice scanner will allow visualization of the pancreatic duct or do you have a recommendations on how to protocol the study?
| Answer: CT cholangiogram with very thin sections in both arterial and venous phase. |
2. What are the protocols for CT cholangiogram using a single slice GE CT High Speed?
| Answer: Use 3 mm thick sections every 3 mm would be the best one could hope for on a single slice scanner. Thinner slice with multiplanar reconstruction is ideal. |
3. With a GE CT Highspeed: We scan 5 mm and reconstruct 3 mm. Still can't get good scans of bile duct tree. How do you manipulate MIP, MPR, MPVR, SSD to do best, obtain good pictures? To any reader, please help ASAP. We do not have advantage workstation, but manipulate everything on the CT console.
| Answer: Use thinner slices 3 mm thick sections every 3 mm. Unfortunately, to get good visualization of ductal structures, you need slice thickness at or under 1 mm. Every workstation has different functionality and the best recommendation is to speak to the vendor for your workstation and give you additional hands on training. We do run 3D courses every April on the east and west coast. |
References
Schroeder T. Malago M. Debatin JF. Testa G. Nadalin S. Broelsch CE. Ruehm SG. Multidetector computed tomographic cholangiography in the evaluation of potential living liver donors. Transplantation. 2002; 73(12):1972-3.
- Summary: This study of 12 potential liver donors involved IV administration of meglumine iodipamide. Using 4 slice MDCT, the protocol involved 1 mm collimation. Acquisitions were performed before and after IV contrast infusion (350 mgI/mL). Results demonstrated that 9 of the 12 patients had biliary anatomic variants.
Yeh BM. Breiman RS. Taouli B. Qayyum A. Roberts JP. Coakley FV. Biliary tract depiction in living potential liver donors: comparison of conventional MR, mangafodipir trisodium-enhanced excretory MR, and multi-detector row CT cholangiography--initial experience. Radiology. 2004; 230(3):645-51.
- Summary: This recent comparative study elucidated that IV cholangiographic contrast enhanced CT resulted in significantly improved biliary tract visualization compared to either MRI technique and both techniques in combination. Morphine was administered to all patients. Sixteen patients were evaluated, 8 with CT and 8 with MRI. The CT technique included premedication with diphenhydramine prior to IV cholangiographic contrast infusion. Using a 4 section scanner, the acquisition began 15 minutes after contrast infusion and included 2.5 mm collimation and a 1.25 mm recontruction interval.
Nino-Murcia M. Jeffrey RB Jr. Beaulieu CF. Li KC. Rubin GD. Multidetector CT of the pancreas and bile duct system: value of curved planar reformations. AJR. 2001; 176(3):689-93.
- Summary: In this pictoral essay, the authors describe the utility of curved planar reformations from 4 slice MDCT. The acquisition protocol included 150 cc of 300 mgI/ml nonionic contrast at 4 cc/second. Scans were obtained 40 seconds after initiation of contrast infusion, at 1.25 mm nominal thickness, reconstructed at .5 mm intervals(pancreatic phase), followed by a 5 mm thickness acquisition at 70 seconds. Curved planar reformations of the pancreatic ducts and bile duct are demonstrated in a number of clinical conditions.