Diagnosis of pulmonary metastases with turbo-SE MR imaging

The sensitivity of MR imaging for detection of pulmonary metastases was evaluated in 23 patients. The MR imaging was performed with T2-weighted turbo-spin-echo (TSE) sequences at 1.5 T. The MR images were compared with spiral volumetric CT which served as the radiological standard. All MR images were interpreted by two radiologists without knowledge of CT findings. The MR imaging technique initially enabled correct identification of altogether 286 of 340 metastases (84 %) resulting in sensitivities of 36 % (size of nodules < 5 mm), 83 % (size of nodules 5-10 mm), 92 % (size of nodules 10-15 mm), and 100 % (size of nodules > 15 mm). Retrospectively with knowledge of CT findings an additional 39 metastases were visible; 15 remained undetected even retrospectively. The results of this paper suggest that MRI still does not have a role for screening for pulmonary metastases. It proves, however, that the incidental diagnosis of a pulmonary lesion on T2-weighted TSE images is highly reliable in representing a pulmonary nodule also visible on CT. However, thus far the malignant nature especially of small nodules detected by MRI (as by CT) remains uncertain even in patients with known malignant neoplasm.