Multidetector CT detection of peritoneal metastases: evaluation of sensitivity between standard 2.5mm axial imaging and maximum-intensity-projection (MIP) reconstructions.

Abstract

Our purpose was to evaluate the sensitivity of multidetector CT for the detection of peritoneal metastases between standard 2.5mm axial imaging and maximum-intensity-projection (MIP) reconstructions. The Institutional Review Board approved this retrospective study and waived the need to obtain patient consent. We retrospectively identified 36 patients with pancreatic adenocarcinoma and peritoneal metastatic disease who underwent a pancreatic protocol CT examination of the abdomen and pelvis between January 2012 and January 2014. Three independent radiologists reviewed a randomized combination of standard axial (2.5mm reconstructed thickness, 2.5mm interval) and axial MIP reconstructions (6, 3mm interval) over two sessions. Each reader recorded metastasis location in PACS. Subsequent consensus review by two radiologists determined the final number and size of metastases. The reviewers found 328 peritoneal implants in 36 patients. After accounting for the size, location, and number of lesions as well as multiple readers, a generalized estimating equations model showed that the statistical combination of MIP with standard technique significantly increased the odds of correctly identifying a lesion (OR 2.16; 95% CI 1.86-2.51; p value<0.0001) compared to standard technique alone. MIP reconstruction as a standalone technique was less sensitive compared to standard technique alone (OR 0.81; 95% CI 0.65-0.99; p value=0.0468). When compared to standard axial imaging, evaluation via MIP reconstructions resulted in the identification of an additional 50 (15%), 45 (14%), and 55 (17%) lesions by Readers 1-3, respectively. The axial 6mm MIP series is complimentary in the CT evaluation of peritoneal metastases. MIP reconstruction evaluation identified a significant number of additional lesions, but is not adequate as a standalone technique for peritoneal cavity assessment.