Diffusion-weighted MR imaging for differentiation of benign fracture edemaand tumor infiltration of the vertebral body

OBJECTIVE. The aim of this study was to investigate diffusion-weighted MR i maging for differentiation of benign fracture edema and tumor infiltration with and without accompanying fracture. SUBJECTS AND METHODS. In 10 volunteers, diffusion-weighted spin-echo, fat-s uppressed spin-echo, and stimulated-echo sequences were optimized on a clin ical 1.5-T scanner. In 34 patients, MR imaging with and without diffusion-s ensitizing gradients (b = 598 sec/mm(2) in spin-echo and fat-suppressed spi n-echo, b = 360 sec/mm(2) in stimulated-echo) was performed. Thirty-five le sions were analyzed, with 18 caused by acute (less than or equal to 10 days old) osteoporotic or traumatic fractures and 17 caused by untreated malign ant vertebral infiltration including nine fractures. Signal attenuation in diffusion-weighted images and contrast-to-noise ratio were calculated. The diffusion-weighted images were analyzed by two radiologists. RESULTS. Images from three of 34 patients were excluded because of motion a rtifact. In osteoporotic and traumatic fractures, a strong signal attenuati on of bone marrow edema was seen. In contrast to this, malignant-tumor infi ltration caused only minor signal attenuation (p < 0.05), independent of ac companying pathologic fracture, All sequences showed identical changes of s ignal intensities. In four patients, initial diagnosis was changed by the f indings in the diffusion-weighted images, CONCLUSION. Diffusion-weighted spin-echo, fat-suppressed spin-echo, and sti mulated-echo sequences are equally suitable for imaging of the spine. Calcu lation of signal attenuation and observation of signal characteristics allo wed differentiation of benign fracture edema and tumor infiltration and pro vided excellent distinction between benign and malignant vertebral fracture s in our series.