Adding whole-body PET/MRI improves evaluation of colorectal cancer

Compared with conventional multi-detector, contrast-enhanced CT (CECT) alone, CECT with integrated whole-body PET/MRI is better at detecting metastatic lesions and characterizing indeterminate lesions in the colon.

The improvement is only partial when imaging small pulmonary metastatic nodules, but overall it points to PET/MRI as a potential aid to guide the selection of more appropriate treatment strategies for patients with colorectal cancer.

The study backing up these conclusions is running in the January edition of the American Journal of Roentgenology.

Beomsik Kang, MD, of Seoul National University College of Medicine in Korea and colleagues reviewed the cases of 51 patients with colorectal cancer who underwent F-18 fluorodeoxyglucose PET/MRI and CECT within a 90-day interval between October 2012 and August 2013.

They found that PET/MRI added value to CECT for 14 of 51 patients (27.5 percent) by leading to better characterization in 12 of the patients (23.5 percent) and/or additional detection of extracolonic lesions in two of them (3.9 percent).

The additional information from PET/MRI led to a change in treatment strategy for 11 of 51 (21.6 percent).

ROC curve analyses showed that PET/MRI was significantly superior to CT in depicting colorectal cancer.

The results suggest that integrated PET/MRI “may add information to the standard contrast-enhanced CT findings regarding metastases in the evaluation of malignant tumors, helping radiologists make a more appropriate selection of the treatment strategy for patients with colorectal cancer,” the authors write in their study discussion.

Given MRI’s many advantages in oncology imaging, “not only for its excellent soft-tissue contrast but also for its multiparametric capability,” they point out, “we believe that PET/MRI may actually be better than PET/CT in the evaluation of certain disease entities, such as soft-tissue sarcoma, primary hepatic malignancy, and hepatic metastases.”