LUMBAR SPINE MAGNETIC-RESONANCE-IMAGING - COMPARISON BETWEEN FAST SPIN-ECHO PROTON DENSITY AND SPIN-ECHO T-1 AXIAL SCANS

Spin echo (SE) T-1 axial scans are routinely obtained in magnetic reso nance imaging of the lumbar spine in many centres. This study directly compared matched SE T-1 and fast SE (FSE) proton density (PD) axial s cans. Both SE T-1 and FSE PD axial scans of the lumbar spine were obta ined in 116 consecutive patients. The imaging parameters (field-of-vie w, slice thickness, interslice gap, number of excitations and matrix s ize) and scan levels were identical for each pair of sequences. At two selected levels, L4/5 and L5/S1, various structures were independentl y graded by two observers. In 232 lumbar levels analysed, the bone mar row, epidural fat, disc, extradural nerve root and facet joint were eq ually well seen on both sequences by both observers (combined mean gra des of 2.93-2.99). The thecal sac was marginally better depicted on FS E PD than on SE T-1 images, with mean grades of 2.96 and 2.88, respect ively. The psoas muscle was adequately visualized for diagnostic purpo ses on both sequences (mean grades of 2.30-2.32). The cauda equina wer e better seen on FSE PD (mean grade 1.92) than on SE T-1 (mean grade 1 .00) images. In conclusion, FSE PD scans are comparable to and may pot entially replace SE T-1 axial MR scans of the lumbar spine.