Background <p>Repeat cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) (rCRS-HIPEC) has improved the long-term survival of select patients with acceptable perioperative morbidity and mortality. The pattern of peritoneal disease recurrence is critical in determining eligibility for rCRS-HIPEC. This study evaluated the accuracy, sensitivity and specificity of the radiological peritoneal cancer index (PCI) across different imaging modalities in rCRS-HIPEC patients.</p> Methods <p>This was a retrospective study on patients with peritoneal disease recurrence who underwent rCRS-HIPEC between January 2022 to December 2023. The accuracy, sensitivity, and specificity of the radiological PCI in predicting the surgical PCI was calculated overall and for each imaging modality at each abdominal region.</p> Results <p>32 patients were included in this study. The accuracy, sensitivity and specificity of the overall radiological PCI was 63.0%, 30.8% and 79.9%, respectively. Accuracy (67.5 vs. 62.6%) and specificity (84.8% vs. 75.8%) were higher in FDG-PET versus CT. The sensitivities of all imaging modalities were low (CT 34.9%, FDG-PET 33.3%). FDG-PET and CT had high sensitivities in detecting pelvic disease (80% and 87.5%) but low sensitivities in identifying small bowel (25-33.3% for both modalities) and epigastric disease (25% and 0%). For each abdominal region, the difference between radiological and surgical PCI did not differ significantly based on imaging modality.</p> Conclusions <p>Overall, the radiological PCI has a good specificity in rCRS-HIPEC patients and should be used to guide perioperative decision-making. FDG-PET had superior accuracy and specificity in comparison to CT in detecting peritoneal disease recurrence.</p>