![]() ( 30) noted sensitivity of helical CT for peritoneal tumors < than 1cm was only 25-50% compared with 85-95% for all tumors. Multidetector CT is commonly used for preoperative imaging in patients undergoing surgical cytoreduction but is very limited in its ability to depict small peritoneal tumors. This study serves as a baseline examination against which follow up MR studies are compared to assess for recurrent tumors (C) appendiceal cancer 2 years following HIPEC: recurrent tumor (arrows) is shown in the left anterior abdomen. The combination of DWI b500 images and delayed gadolinium-enhance MR images is most useful for preoperative imaging of patients prior to surgical cytoreduction and HIPEC (B) appendiceal cancer: initial surveillance MRI 6 months following surgical cytoreduction and HIPEC does not show residual tumor PCI =0. (A) Appendiceal cancer: preoperative MRI shows bulky upper abdominal peritoneal tumor (arrows) MRI PCI =39 and surgical PCI =39. In our experience the combination of diffusion weighted imaging (DWI) and delayed gadolinium-enhanced MR imaging is most accurate for detecting peritoneal tumors ( 34, 35) ( Figure 2). Most tumors restrict water diffusion causing them to appear as high signal areas on diffusion images. Diffusion-weighted (DW) MR images assess microscopic movement of water protons ( 32, 33). The addition of diffusion imaging to the MRI tool chest further improves peritoneal tumor depiction. The increased conspicuity of these enhancing peritoneal tumors improved detection of small and microscopic tumors that are often missed on CT scans ( 30, 31) ( Figure 1). Initial experience confirmed that peritoneal tumors show marked enhancement on images obtained 5 min after administration of gadolinium contrast material ( 28, 29). While CT is limited to assessing attenuation of X-rays, MR imaging uses multiple contrast mechanisms to improve its sensitivity for depicting small peritoneal tumors. Comparisons with alternative imaging tests such as CT and the clinical utility of MR imaging for preoperative assessment of peritoneal cancer index (PCI) and for surveillance of patients following CRS and HIPEC will be described. Image interpretation in the preoperative and surveillance setting will be discussed. In this article we will discuss the technical issues surrounding peritoneal MR imaging, including patient preparation and MR scanning protocols. Following CRS and HIPEC surveillance imaging combined with serial tumor markers are routinely used to detect recurrent tumor ( 27). Careful patient selection based on preoperative imaging may prevent unnecessary surgeries in patients whose tumors are too extensive and cannot be adequately cytoreduced. Preoperative MRI and CT of the abdomen and pelvis play an integral role in determining the extent of peritoneal and visceral disease in patients being considered for CRS and HIPEC for appendiceal, ovarian, colorectal, primary peritoneal, gastric, mesothelioma and other rare types of gastrointestinal disease involving the peritoneum ( 18- 26). For patients undergoing CRS and HIPEC the PCI is one factor associated with determining whether a complete surgical cytoreduction can be achieved ( 17). The PCI is the most widely validated and precise quantitative prognostic indicator ( 14- 16). ![]() ![]() The important role of surgical cytoreduction and heated intraperitoneal chemotherapy (HIPEC) in patients with peritoneal surface malignancies is well established ( 1- 13).
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