Follow-up of known carcinoid liver metastases: is respiratory-gated t(2) fast spin-echo enough?

To compare the reliability of T(1)-weighted, T(2)-weighted, and different phases of dynamic contrast-enhanced MRI in the detection and reproducible size assessment of known carcinoid hepatic metastases.22 patients with known carcinoid hepatic metastases qualified for the study. Three readers reviewed MRI images twice independently at sessions that were2 weeks apart. The best sequences for metastases conspicuity, number and size, and reproducibility of size were compared subjectively. Linear mixed models were used to compare the number and size of metastases between readers and sequences, with the significance level set at p0.05.The best overall sequence rated was T(2) FSE (fast spin-echo). The average numbers of metastases was equivalent using T(1)-weighted arterial and T(2) FSE but less for T(2) FRFSE (fast-recovery, fast spin-echo) or delayed imaging. 1,067 lesions were detected and 66 were measured twice by three readers. There was no significant difference between the sequences or between the readings in size measurement when the same sequence was used. However, there was a difference among sequences for size of metastases (p0.001).T(2) FSE can be used as a basic sequence in detecting and monitoring the size of carcinoid hepatic metastases and may serve as the primary sequence in patients with contrast allergy or at risk for nephrogenic systemic fibrosis.