Whole-body MRI with diffusion-weighted imaging as an adjunct to 18 F-fluorodeoxyglucose positron emission tomography and CT in patients with suspected recurrent colorectal cancer

• Published in: Colorectal disease 2024-02, Vol.26 (2), p.290-299
• Main Authors: Willemse, Jeroen R J, Lahaye, Max J, Kok, Niels F M, Grotenhuis, Brechtje A, Aalbers, Arend G J, Beets, Geerard L, Rijsemus, Charlotte, Maas, Monique, van Golen, Larissa W, Beets-Tan, Regina G H, Lambregts, Doenja M J
• Format: Article
• Language: English
• ISSN: 1462-8910; 1463-1318
• DOI: 10.1111/codi.16840

The aim was to explore how findings of whole-body MRI including diffusion-weighted imaging (DW-MRI) compared to the routine diagnostic workup with CT and/or F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in patients with suspected recurrent colorectal cancer (CRC). This was an exploratory retrospective analysis of 55 patients with a clinical suspicion of recurrent CRC who underwent DW-MRI following CT and/or FDG-PET/CT. Two readers in consensus interpreted all clinical imaging reports and converted each described lesion into a confidence score (1 = definitely benign to 5 = definitely malignant). DW-MRI findings were compared to the most recent previous CT or PET/CT. Any discrepant or additional DW-MRI findings were documented and compared with histology and/or clinical follow-up (if available). Whole-body MRI including diffusion-weighted imaging (DW-MRI) resulted in discrepant/additional findings in 26/55 (47%) cases; 23/37 (62%) compared to previous CT and 3/18 (17%) compared to previous PET/CT. These included 10 cases where DW-MRI converted previously inconclusive CT (n = 8) or PET/CT (n = 2) findings into a conclusive diagnosis, one where it contradicted a previous CT diagnosis of recurrence, five where DW-MRI diagnosed recurrent disease not previously reported on CT and 10 cases where DW-MRI detected additional lesions compared to CT (n = 9) or PET/CT (n = 1). Eighty-eight per cent of cases with discrepant/additional findings concerned patients with recurrent/metachronous peritoneal metastases. In total, DW-MRI resulted in 42 discrepant/additional lesions; the DW-MRI diagnosis was correct in 76% of these lesions and incorrect (false positive) in 7%. In the remaining 17%, no standard of reference was available. This explorative study suggests that DW-MRI may be of added value to patients with a clinical suspicion for recurrent CRC, in particular to identify patients with peritoneal metastases. DW-MRI mainly has potential as a 'problem-solver' in patients with inconclusive or negative findings on previous imaging (in particular CT) and to detect additional disease sites in patients already diagnosed with recurrent disease.