Janio Szklaruk, MD, PhD

The advent of     multislice CT, advanced computer workstations, and 3D and postprocessing     algorithms has allowed for new perspectives from which to view imaging     data. These are especially useful for pancreatic cancer and biliary     pathology. They can be used by the radiologist for problem solving and     facilitated communication between the radiologist and the referring     clinician, aiding diagnosis, illustrating disease extent, describing     staging clearly, and guiding surgical planning.

 Acquisition of suitable source images for     postprocessing is vital. We acquire 2.5-mm contiguous images for     interpretation and reconstruct them to either 1.25 mm every 0.625 mm or as     contiguous 0.625-mm images depending on the capabilities of the     particular CT scanner being used for postprocessing.

Images are obtained of the entire abdomen during two     phases: the peak pancreatic parenchymal phase of enhancement, to     maximize visualization of tumor and arteries, and the portal venous phase     for liver metastases, veins, and the pancreatic duct.

 Using a rapid injection     rate of 4 to 5 cc/sec for 30 seconds, we achieve peak pancreatic     enhancement at approximately 40 to 45 seconds after the start of     contrast injection. The portal venous phase is approximately 60 seconds     after the start. Bolus tracking is used to adjust for cardiac circulation     time.

Multiple techniques are available for postprocessing.     Coronal multiplanar reconstructions (also known as raysum) using     2.5-mm-thick slices every 2.5 mm provide excellent visualization of the     relationship of tumor to adjacent structures. Maximum intensity projection     (MIP) images or angiographic technique volume-rendered images created as a     rotating coronally oriented 5-cm slab or semithick 10-mm coronal images     every 2.5 mm are useful to display vascular anatomy.  

Minimum intensity projection (MinIP) images, 15-mm     thick every 2.5 mm in the coronal plane, are useful to show hilar and     extrahepatic biliary pathology, the pancreatic duct, and,     particularly, side branch dilatation and potential communication with     cystic lesions. Curved planar reformations can be very helpful in providing     a concise summary of findings. In all cases, images should be reviewed by a     radiologist to confirm that they convey information accurately, especially     if they are ultimately to be viewed by a nonradiologist. 

The approach must vary depending on the problem to be     solved. 

. Axial images are typically     sufficient for evaluation of the superior mesenteric artery and, in most     cases, the celiac trunk. In our experience, however, coronally     oriented images are very useful for showing the relationship of tumor,     especially in the pancreatic head, with the common hepatic artery     (Figure 1). It is also useful for evaluating the length of the superior     mesenteric vein and/or portal vein involvement in cases of potential     venous bypass graft placement (Figure 2). These images are also useful for     showing the craniocaudal extent of disease. Recent studies have confirmed     that postprocessed images can improve the accuracy of staging pancreatic     cancer.

The presence of a vascular variant, particularly an     accessory or replaced right hepatic artery, is important to note because it     crosses the surgical field of resection and, in our experience, is often at     risk for involvement by pancreatic head tumors (Figure 3). Coronally     oriented images are also useful for showing dilated pancreatic duct side     branches extending from small cystic lesions, which may help in the     suggestion of pseudocysts or side branch intraductal papillary mucinous     neoplasms.

. Surgical planning for     resection of hilar cholangiocarcinomas requires precise identification of     the degree of involvement of the biliary tree and portal vein branches,     particularly if there is evidence of bilateral disease, which typically     precludes surgery. This can be aided by coronally oriented images,     including raysum, MIP, and MinIP of CT data.

Indeed, CT cholangiopancreatography has been shown to     have image quality similar to endoscopic retrograde     cholangiopancreatography as well as similar accuracy in identifying the     level and cause of obstruction.

MR cholangiopancreatography data can also be manipulated     using MIP or volume rendering, with selective editing, to provide     additional detail regarding the biliary tree. Use of MRCP and MR     angiography has been shown to be effective in diagnosing the level of     obstruction, arterial ivolvement, and venous invasion.

More complex techniques, such as segmental volume     measurements, are useful when techniques like preoperative portal vein     embolization are used to predict if the resultant hypertrophy of     nonembolized segments is sufficient to preclude significant postoperative     morbidity.		

Postprocessing can also be very helpful in     understanding postoperative changes. This approach is especially useful     when tumor recurrence, such as in pancreatic cancer, distorts already     complex surgical anatomy.

Images can be delivered to the clinician in a variety     of ways, including CD, enterprise PACS, dedicated web server with     illustrated reports, or even film. The ability to do real-time processing     anywhere, such as with thin-client solutions, allows on-demand 3D     processing at multidisciplinary conferences to convey complex data to     clinicians regarding pancreatic cancer or biliary pathology.

	Several postprocessing or 3D techniques allow the     radiologist to gain new perspectives from which to view CT and MRI data.     These can aid understanding of complex anatomy that would be extremely     difficult to obtain from axial images alone, leading to improved diagnosis, staging, and     communication of findings.		

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Articles

The advent of multislice CT, advanced computer workstations, and 3D and postprocessing algorithms has allowed for new perspectives from which to view imaging data. These are especially useful for pancreatic cancer and biliary pathology.

Janio Szklaruk, MD, PhD

Articles

Three-D techniques showcase the pancreas and biliary