[Staging of spinal metastasis using special techniques of magnetic resonance imaging]

The diagnosis of spine metastasis is a problem of great interest which leaves many questions unanswered. In this field MR imaging plays a fundamental role, as the only technique able to directly demonstrate the changes in bone marrow tissue, bound to tumoral activity. The introduction of gradient-echo (GE) sequences has helped reduce examination time. Moreover, with the accurate choice of pulse-sequence parameters (TR, TE, flip angle) additional information is acquired which is not yielded by conventional spin-echo (SE) sequences. Our study was aimed at evaluating MR sensitivity in the different stages of bone metastatic evolution. The comparative adequacy was evaluated of combined bone scintigraphy and conventional radiology versus MR imaging in 62 patients with vertebral metastases. Time interval between bone scan and/or radiological study and MR exam ranged from 10 days to 8 months. SE and GE T1-weighted images, and SE and GE T2-weighted images on the sagittal plane were employed, and axial images; coronal images were rarely acquired. Metastases were demonstrated by MR imaging at 122 vertebral levels, versus 88 true positives of combined scintigraphy and conventional radiology. Scintigraphic false-positives were observed at 15 vertebral levels, versus 9 with radiography. GE sequences were superior to SE ones in detecting vertebral morphologic lesions and bone marrow involvement thanks to their improved resolution and sensitivity. Moreover, GE sequences demonstrated tumoral bone marrow spread and persistent tumoral activity in the follow-up of spine metastases. Our results point to GE sequences as those of choice because of their higher resolution and sensitivity, which also allow response to treatment to be evaluated.