Nuclear medicine and MRI in differential diagnosis of doubtful spinal disorders

Full text: Purpose of presentation is a retrospective analysis and pictorial assay of MRI in differential diagnosis of spinal diseases with increased Tc-99m-MDP uptake on the whole body bone scan. A retrospective analysis of 200 spine cases was carried out in respect of metastatic, osteoporotic and degenerative bony lesions with similar appearance of bone scan. Referring diagnoses were either spinal pain syndromes or tumour staging. Double headed gamma camera (ADAC) and a low field whole body (0.3 T, Hitachi) scanner were used. Bone scan, SPECT and routine SE T1 and SE T2 sequences were completed with STIR and Gd contrast administration in selected complicated cases. Recently additional opposed phase GRE sequences were used as well. In doubtful whole body scintigraphic cases, SPECT study was performed. Cases with uncertain diagnosis were sent for MRI study. Increased T2 signal and decreased T1 signal, if diffusely distributed in the vertebral body, is characteristic to recent osteoporotic compressions. In cases of non-compressed (metastatic) vertebral bodies with diffuse increased T2 signal increase this appearance had predictive value of imminent compression fracture. Increased T2 signal with decreased T1 signal in adjacent vertebral bodies accompanied by irregularity of contours and of signal intensity involving the inter-vertebral disc, and Gd enhancement were symptoms of infection, in particularly spondylodiscitis. Opposed phase GRE sequences seems to be optimal in differentiation of metastatic lesions versus porotic lesions. We conclude that routine bone scan, and MRI in selected patients suffering from back pain syndrome can help differentiation of osteoporotic versus metastatic and degenerative vertebral lesions. Additional STIR sequence, Gd administration and opposed phase GRE imaging make the diagnosis more specific. (author)