Whole-body MRI at 1.5 T and 3 T compared with FDG-PET-CT for the detection of tumour recurrence in patients with colorectal cancer

Abstract

The purpose of this study was to assess the diagnostic accuracy of whole-body MRI (WB-MRI) at 1.5 T or 3 T compared with FDG-PET-CT in the follow-up of patients suffering from colorectal cancer. In a retrospective study, 24 patients with a history of colorectal cancer and suspected tumour recurrence underwent FDG-PET-CT and WB-MRI with the use of parallel imaging (PAT) for follow-up. High resolution coronal T1w-TSE and STIR sequences at four body levels, HASTE imaging of the lungs, contrast-enhanced T1w- and T2w-TSE sequences of the liver, brain, abdomen and pelvis were performed, using WB-MRI at either 1.5 T (n = 14) or 3 T (n = 10). Presence of local recurrent tumour, lymph node involvement and distant metastatic disease was confirmed using radiological follow-up within at least 5 months as a standard of reference. Seventy seven malignant foci in 17 of 24 patients (71%) were detected with both WB-MRI and PET-CT. Both investigations concordantly revealed two local recurrent tumours. PET-CT detected significantly more lymph node metastases (sensitivity 93%, n = 27/29) than WB-MRI (sensitivity 63%, n = 18/29). PET-CT and WB-MRI achieved a similar sensitivity for the detection of organ metastases with 80% and 78%, respectively (37/46 and 36/46). WB-MRI detected brain metastases in one patient. One false-positive local tumour recurrence was indicated by PET-CT. Overall diagnostic accuracy for PET-CT was 91% (sensitivity 86%, specificity 96%) and 83% for WB-MRI (sensitivity 72%, specificity 93%), respectively. Examination time for WB-MRI at 1.5 T and 3 T was 52 min and 43 min, respectively; examination time for PET-CT was 103 min. Initial results suggest that differences in accuracy for local and distant metastases detection using FDG-PET-CT and WB-MRI for integrated screening of tumour recurrence in colorectal cancer depend on the location of the malignant focus. Our results show that nodal disease is better detected using PET-CT, whereas organ disease is depicted equally well by both investigations.

The value of FDG positron emission tomography/computerised tomography (PET/CT) in pre-operative staging of colorectal cancer: a systematic review and economic evaluation.

“…When gender proportions were reported, men were usually in the majority, with the exception of two studies 66,67 that reported mostly women and two studies 62,65 that did not report gender. The mean ages of patients when reported were 55-65 years, with a range of 33-91 years.…”

“…The distinction between cancer of the colon and rectum was not reported in four studies, 61,63,65,67 in two the population was mixed (colon and rectal disease) 66,68 and two studies reported outcomes in people with a diagnosis of rectal cancer. 62,64 …”

“…The search identified eight studies [61][62][63][64][65][66][67][68] that evaluated the diagnostic test accuracy of integrated FDG PET/CT for the detection of colorectal recurrence.…”

“…Patients received oral 67,68 or intravenous 65 contrast agents with the CT component of the FDG PET/CT test in three studies. One study 64 reported a mixture of contrast-enhanced CT and noncontrast-enhanced CT images obtained from study patients.…”

“…64,67,68 Positive lesions from the PET component were defined as those associated with a focal increased uptake of FDG which was greater than that of the background tissues, 61,63 any new tissue close to an anastomosis with asymmetrical, or irregular, contrast enhancement or changes compared with previous findings, 62 signs of aggressive expansion of a lesion and ill-defined borders or erosion/infiltration of neighbouring tissues. 65 No information regarding the methods of assessment was given in one study. 66 …”