Assessment of Musculoskeletal Malignancies with Functional MR Imaging

Magnetic resonance imaging of the knee: An overview and update of conventional and state of the art imaging

“…30 Diffusion weighting with echo planar imaging takes advantage of the high cellularity within soft-tissue neoplasms, with a resulting hyperintense signal on diffusion-weighted images and hypointense signal on the apparent diffusion coefficient (ADC) map. 31 A lower ADC correlates with a higher risk of malignancy in softtissue lesions. 32 Diffusion-weighted imaging is most beneficial in cases where intravenous contrast cannot be administered or as an adjunct to gadolinium in postoperative cases to increase specificity over gadolinium images alone.…”

“…A decrease in signal on the opposed‐phase image by 20% or more relative to the in‐phase image is suggestive of a benign etiology that is not replacing marrow fat . Diffusion weighting with echo planar imaging takes advantage of the high cellularity within soft‐tissue neoplasms, with a resulting hyperintense signal on diffusion‐weighted images and hypointense signal on the apparent diffusion coefficient (ADC) map . A lower ADC correlates with a higher risk of malignancy in soft‐tissue lesions .…”

“…Dynamic contrast‐enhanced imaging may be of particular benefit in the follow‐up of soft‐tissue sarcomas after treatment, with a recent study showing a 97% specificity for recurrent tumor compared to 52% for conventional postcontrast images . MR spectroscopy assesses the chemical composition of tissue, with a higher percentage of choline suggestive of malignancy due to an increased rate of phospholipid membrane turnover . Spectroscopy of musculoskeletal lesions is in its early stages of development, but has shown promise in being able to distinguish malignant from benign lesions …”

MRI biomarkers in osseous tumors

“…Previous literature used two different types of techniques to perform proton MRS: single‐voxel (SV) techniques or a multivoxel magnetic resonance spectroscopic imaging (MRSI) techniques. Because metabolite information from only one region of the lesion is provided with the SV techniques, the voxel should be placed in a solid and homogeneous tumor area excluding hemorrhage, necrosis, and calcification . The voxel should be placed in the area with maximum contrast enhancement, if contrast‐enhanced images are available.…”

“…Because metabolite information from only one region of the lesion is provided with the SV techniques, the voxel should be placed in a solid and homogeneous tumor area excluding hemorrhage, necrosis, and calcification. 95 The voxel should be placed in the area with maximum contrast enhancement, if contrast-enhanced images are available. MRSI can obtain metabolite information simultaneously from several voxels within a large field of view.…”