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Diffusion-Weighted Imaging of Usual and Unusual Tumor and Tumor-Like Lesions in the Spine 2013

Category General Spine Toshio Moritani
Charles Smittkamp
Jack Kademian
Purpose We address the utility of diffusion-weighted imaging (DWI) along with the corresponding apparent diffusion coefficient (ADC) maps in the evaluation of spinal lesions by assessing individual cases across a wide range of pathologies.  By assessing common tumors, unusual tumors, and tumor-like lesions, we will show that DWI can be a helpful tool in lesion detection, lesion assessment, and in distinguishing malignant from benign processes. Materials & Methods The DWI and ADC sequences from a total of 270 patient MRIs showing spinal lesions previously diagnosed through a combination of clinical, imaging, and pathological findings were reviewed.  The DWI images were of the spin-echo, echo-planar type with parallel imaging, and the ADC maps were calculated from b values of 0 and 1000 sec/mm2. The lesions evaluated included both primary and secondary malignant tumors as well as benign tumors and tumor-like lesions.  They are comprised of lytic and sclerotic bone metastases from a variety of primary lesions (including lung, breast, prostate, glioblastoma, and clear cell meningioma), multiple myelomas, lymphomas, leukemia, osteosarcomas, chordomas, a variety of primary bone tumors (including osteoid osteoma, giant cell tumor, Langerhans histiocytosis), multiple hemangiomas (both atypical and infiltrating type), notochord rests, bone marrow edema with Schmorl’s nodes, osteomyelitis with granuloma formations, bone necrosis, and traumatic bone lesions. Results DWI often shows hyperintensity with low corresponding ADC values in various malignant bone tumors due to their hypercellularity.  Benign conditions do not demonstrate the same hyperintensity.  These findings can be useful in detection of a tumor as well as in differentiating malignant and benign conditions (such as typical from atypical/infiltrating hemangiomas).  There were, however, some limitations to this result.  First, sclerotic bone lesions, even when malignant, did not demonstrate the same DWI hyperintensity, and the ADC values were difficult to evaluate.  Additionally, susceptibility artifacts such as nearby surgical devices sometimes inhibited interpretation.  Finally, the calculation of ADC values were sometimes hampered due to lesional tissue containing bone or fat. Conclusion We show how DWI and ADC provide utility in the evaluation of the wide variety of spinal lesions.  These sequences can aid in the initial detection of lesions; they can help decide the likelihood of a lesion’s malignancy by demonstrating hyperintensity due to increased cellularity; and they can be especially helpful in distinguishing between malignant and benign processes that may otherwise appear similar, such as between a hemangioma and atypical/infiltrating hemangioma. We demonstrate these utilities through case examples of a variety of common tumors, unusual tumors, and tumor-like lesions in the spine. References Pui MH, Mitha A, Rae WI, Corr P. Diffusion-weighted magnetic resonance imaging of spinal infection and malignancy. J Neuroimaging. 2005;15:164-170. Thurnher MM, Bammer R. Diffusion-weighted magnetic resonance imaging of the spine and spinal cord. Semin Roentgenol. 2006;41:294-311. Oner AY, Akpek S, Tali T, Ucar M. Giant vertebral notochordal rest: Magnetic resonance and diffusion weighted imaging findings. Korean J Radiol 2009;10:303-306