Diagnostic performance of 18F-fluorodeoxyglucose-PET/MRI versus MRI alone in the diagnosis of pelvic recurrence of rectal cancer

Research output: Contribution to journalResearch articleContributedpeer-review



PURPOSE: To compare the diagnostic performance of 18F-fluorodeoxyglucose-PET/MRI and MRI in the diagnosis of pelvic recurrence of rectal cancer.

METHODS: All PET/MRIs of patients in the follow-up of rectal cancer performed between 2011 and 2018 at our institution were retrospectively reviewed. Recurrence was confirmed/excluded either by histopathology or imaging follow-up (> 4 months). Four groups of readers (groups 1/2: one radiologist each, groups 3/4: one radiologist/one nuclear medicine physician) independently interpreted MRI and PET/MRI. The likelihood of recurrence was scored on a 5-point-scale. Inter-reader agreement, sensitivity, specificity, PPV/NPV and accuracy were assessed. ROC curve analyses were performed.

RESULTS: Fourty-one PET/MRIs of 40 patients (mean 61 years ± 10.9; 11 women, 29 men) were included. Sensitivity of PET/MRI in detecting recurrence was 94%, specificity 88%, PPV/NPV 97% and 78%, accuracy 93%. Sensitivity of MRI was 88%, specificity 75%, PPV/NPV 94% and 60%, accuracy 85%. ROC curve analyses showed an AUC of 0.97 for PET/MRI and 0.92 for MRI, but the difference was not statistically significant (p = 0.116). On MRI more cases were scored as equivocal (12% versus 5%). Inter-reader agreement was substantial for PET/MRI and MRI (0.723 and 0.656, respectively).

CONCLUSION: 18F-FDG-PET/MRI and MRI are accurate in the diagnosis of locally recurrent rectal cancer. Sensitivity, specificity, PPV, NPV and accuracy are comparable for both modalities, but PET/MRI increases readers' confidence levels and reduces the number of equivocal cases.


Original languageEnglish
Pages (from-to)5086-5094
Number of pages9
JournalAbdominal radiology
Issue number11
Publication statusPublished - Nov 2021

External IDs

PubMedCentral PMC8502129
Scopus 85112755032
ORCID /0000-0001-7096-5199/work/146643546
ORCID /0000-0001-5061-9643/work/147674437


Sustainable Development Goals


  • Female, Fluorodeoxyglucose F18, Humans, Magnetic Resonance Imaging, Male, Neoplasm Recurrence, Local/diagnostic imaging, Positron-Emission Tomography, Radiopharmaceuticals, Rectal Neoplasms/diagnostic imaging, Retrospective Studies, Sensitivity and Specificity

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