Osseous metastasis from XXXX : "flow-void" sign at MR imaging.

@entity1 @entity1358 @entity703
PURPOSE: To characterize the appearance and determine the importance of the "flow-void" sign on magnetic resonance (MR) images of @entity1 with osseous metastasis from @entity1358 . MATERIALS AND METHODS: Three musculoskeletal radiologists retrospectively and independently reviewed the medical records of 16 @entity1 who had undergone MR imaging and in whom 20 osseous metastatic lesions from @entity1358 had been diagnosed on the basis of clinical and radiologic findings. They assessed the MR images for the presence and frequency of the flow-void sign--multiple dot-like or tubular structures with low signal intensity. They then compared these findings on MR images with the corresponding areas on available images obtained with radiography (n = 16), computed tomography (CT) (n = 6), and digital subtraction angiography (n = 3) and with the results of histopathologic analysis for the same @entity1 group. They noted the location, diameter, and appearance of the lesion and the flow-void sign, as well as variations in signal intensity within the lesion and among lesions. Statistical analysis was performed to determine the level of interobserver agreement. RESULTS: Radiographic findings and the level of signal intensity on MR images were nonspecific for diagnosis of osseous metastasis from @entity1358 . The flow-void sign was identified at the lesion core or margin with a mean frequency of 76.7% by the three observers (in 15, 16, and 15 of 20 lesions, by observers 1, 2, and 3, respectively). Most of these areas of low signal intensity were tubular structures of less than 3 mm in diameter; in three lesions, they measured 5-8 mm in diameter. In 14 lesions, these structures corresponded to dilated blood vessels or veins identifiable on CT images (six lesions) or digital subtraction angiographic images (four lesions) or at histopathologic analysis (four lesions). The flow-void sign on MR images corresponded to vessels depicted on the CT scans available for six lesions and on the angiographic images available for four lesions. CONCLUSION: Observation of the flow-void sign in lesions depicted on musculoskeletal MR images may prove helpful for diagnosing osseous metastasis from @entity1358 and for treatment planning, especially in @entity1 with occult or forgotten primary @entity703 .
