Combined diffusion-weighted and gadolinium-enhanced MRI can accurately predict the peritoneal cancer index preoperatively in patients being considered for cytoreductive surgical procedures

Our plain-English summary of Combined diffusion-weighted and gadolinium-enhanced MRI can accurately predict the peritoneal cancer index preoperatively in patients being considered for cytoreductive surgical procedures, by R.N. Low, R.M. Barone (Annals of Surgical Oncology, 2012).

The study

• Authors: R.N. Low, R.M. Barone
• Journal: Annals of Surgical Oncology
• Published: 2012;19(5):1394-1401
• Cited by: 104 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: To determine whether abdominal and pelvic magnetic resonance imaging (MRI) with diffusion-weighted and dynamic gadolinium-enhanced imaging can be used to accurately calculate the peritoneal cancer index (PCI) before surgery compared to the PCI tabulated at surgery.

Methods: Thirty-three patients underwent preoperative MRI followed by cytoreductive surgery for primary tumors of the appendix (n = 25), ovary (n = 5), colon (n = 2), and mesothelioma (n = 1). MRIs were retrospectively reviewed to determine the MRI PCI. These scores were then compared to PCI tabulated at surgery. Patients were categorized as having small-volume tumors (PCI 0–9), moderate-volume tumors (PCI 10–20), and large-volume tumors (PCI > 20). The respective anatomic site scores for both MRI and surgery were compared.

Results: There was no significant difference between the MRI PCI and surgical PCI for the 33 patients (P = 0.12). MRI correctly predicted the PCI category in 29 (0.88) of 33 patients. Compared to surgical findings, MRI correctly predicted small-volume tumor in 6 of 7 patients, moderate-volume tumor in 3 of 4 patients, and large-volume tumor in 20 of 22 patients. MRI and surgical PCI scores were identical in 8 patients (24%). A difference of <5 was noted in 16 patients (49%) and of 5–10 in 9 patients (27%). Compared to surgical-site findings, MRI depicted 258 truly positive sites of peritoneal tumor, 35 falsely negative sites, 35 falsely positive sites, and 101 truly negative sites, with a corresponding sensitivity of 0.88, specificity of 0.74, and accuracy of 0.84.

Conclusions: Combined diffusion-weighted and gadolinium-enhanced peritoneal MRI accurately predicts the PCI before surgery in patients undergoing evaluation for cytoreductive surgery.

In plain English

This retrospective study, from Sharp Memorial Hospital in San Diego, tested whether a type of abdominal and pelvic MRI could estimate the peritoneal cancer index, a score of how much tumor lines the abdomen, before surgery. The authors compared the MRI scores with the scores recorded during surgery in 33 patients treated between 2006 and 2010. The surgical oncologist chose these patients. Twenty-five had tumors of the appendix, five of the ovary, two of the colon, and one had mesothelioma. The study did not look at asbestos exposure. The MRI and surgical scores did not differ significantly (P = 0.12). MRI placed 29 of 33 patients in the correct tumor-volume category. Across body regions, MRI showed a sensitivity of 88%, a specificity of 74% and an accuracy of 84%. The authors concluded that this MRI can accurately predict the score before surgery. They noted that the study was small, that most patients had advanced tumor, which likely overestimated how well MRI performed, and that MRI is less accurate when there is little tumor.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective study comparing preoperative MRI with findings at surgery (diagnostic accuracy study)
• Who was studied: 33 patients (24 women, 9 men, mean age 50) who had preoperative MRI and then cytoreductive surgery at Sharp Memorial Hospital, San Diego, between January 2006 and December 2010. Primary tumors were appendix (25), ovary (5), colon (2) and mesothelioma (1). They were nonconsecutive patients selected by the surgical oncologist.
• Exposure: No asbestos or other exposure was studied. The test evaluated was MRI using diffusion-weighted images and delayed gadolinium-enhanced images taken 5 minutes after contrast injection.
• Main results:
  • Across all 33 patients, there was no statistically significant difference between MRI scores and surgical scores (P = 0.12)
  • MRI correctly predicted the tumor-volume category in 29 of 33 patients
  • MRI correctly predicted small-volume tumor in 6 of 7 patients
  • MRI correctly predicted moderate-volume tumor in 3 of 4 patients
  • MRI correctly predicted large-volume tumor in 20 of 22 patients
  • MRI and surgical scores were identical in 8 patients (24%)
  • At the level of individual body regions, MRI correctly showed tumor in 258 regions, with 35 false-negative and 35 false-positive regions. Region sensitivity was 88%, specificity 74% and accuracy 84%.
  • MRI sensitivity rose with tumor size: 78% for the smallest tumors (about 0.5 cm), 88% for tumors 0.6 to 5 cm, and 97% for tumors larger than 5 cm
• The authors' conclusion: The authors concluded that combined diffusion-weighted and delayed gadolinium-enhanced MRI can accurately predict the peritoneal cancer index before surgery in patients being considered for cytoreductive surgery and heated intraperitoneal chemotherapy.
• Limitations the authors state:
  • Small number of patients; the authors said a larger multi-institutional study is needed
  • Most patients (22) had advanced tumor and only 11 had low to moderate tumor. The authors said this likely overestimated MRI performance, and that MRI is less accurate with small-volume tumor.
  • The MRIs were read by a highly experienced radiologist; the authors said a learning curve is expected for new radiologists
  • Agreement between different MRI readers was not assessed
  • MRI availability and cost may limit its use at some centers

Topics

The National Library of Medicine indexes this study under subjects our site covers: Colon cancer, Mesothelioma, Ovarian cancer.

Medical terms in this study, explained in our Lexicon: Peritoneal Cancer Index (PCI), Cytoreductive Surgery, Mesothelioma.

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