Diffusion-weighted MRI assessment of the peritoneal cancer index before cytoreductive surgery

Abstract

Background: Patients with limited peritoneal metastases from colorectal cancer may be candidates for an aggressive surgical approach including cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). Selection is based on surgical inspection during laparoscopy or laparotomy. The aim of this study was to investigate whether diffusion-weighted MRI (DW-MRI) can be used to select patients for CRS-HIPEC.Methods: This was a prospective study at a tertiary referral centre. Patients with confirmed or suspected colorectal peritoneal metastases scheduled for exploratory laparotomy or laparoscopy were eligible. Two radiologists assessed the peritoneal cancer index (PCI) on CT (CT-PCI) and DW-MRI (MRI-PCI). The reference standard was PCI at surgery. Radiologists were blinded to the surgical PCI and to each other's findings. The main outcome was the accuracy of DW-MRI in predicting whether patients had resectable disease (PCI less than 21) or not.Results: Fifty-six patients were included in the study, of whom 49 could be evaluated. The mean(s.d.) PCI at surgery was 11⋅27(7⋅53). The mean MRI-PCI was 10⋅18(7⋅07) for reader 1 and 8⋅59(7⋅08) for reader 2. Readers 1 and 2 correctly staged 47 of 49 and 44 of 49 patients respectively (accuracy 96 and 90 per cent). Both readers detected all patients with resectable disease with a PCI below 21 at surgery (sensitivity 100 per cent). No patient was overstaged. The intraclass correlation (ICC) between readers was excellent (ICC 0⋅91, 95 per cent c.i. 0⋅77 to 0⋅96). MRI-PCI had a stronger correlation with surgical PCI (ICC 0⋅83-0⋅88) than did CT-PCI (ICC 0⋅39-0⋅44).Conclusion: DW-MRI is a promising non-invasive tool to guide treatment selection in patients with peritoneal metastases from colorectal cancer.

Diagnostic Laparoscopy as a Selection Tool for Patients with Colorectal Peritoneal Metastases to Prevent a Non-therapeutic Laparotomy During Cytoreductive Surgery

“…In the near future, it is possible that DLS will play a smaller role in patient selection because detection rates of PM from current preoperative imaging modalities are improving. 27,28 In a recent study consisting of 49 patients with colorectal PM, MRI PCI was strongly correlated with the surgical PCI. 28 Two radiologists with extensive experience in detecting colorectal PM could identify all patients with resectable disease based on a PCI score below 21.…”

“…27,28 In a recent study consisting of 49 patients with colorectal PM, MRI PCI was strongly correlated with the surgical PCI. 28 Two radiologists with extensive experience in detecting colorectal PM could identify all patients with resectable disease based on a PCI score below 21. Larger series are still necessary to provide more evidence of the accuracy of detection and staging of colorectal PM.…”

Circulating Tumor DNA as a Preoperative Marker of Recurrence in Patients with Peritoneal Metastases of Colorectal Cancer: A Clinical Feasibility Study

“…Two recent studies showed the feasibility of DW-MRI to improve the detection and quantification of colorectal PMs compared to conventional CT imaging [ 25 , 53 ]. However, DW-MRI could underestimate the extent of metastases, especially of signet ring cell or mucinous adenocarcinomas [ 25 , 53 ]. In our study, 9/30 (30%) patients had these sub-types so may not have benefitted from DW-MRI alone.…”

Comparison of the Peritoneal Cancer Index and Dutch region count as tools to stage patients with peritoneal metastases of colorectal cancer

“…Promising results [33][34][35] have also been reported using diffusion-weighted (DW) MRI (DW-MRI) to predict a PCI below 21. This accuracy was significantly better than the diagnostic value reported for CT, and may lead to the omission of laparoscopy in patients with a low (less than 10) or high (more than 24) PCI score 35 . However, DW-MRI is time-consuming, and patients are usually staged using CT, also to check for extraperitoneal disease.…”