40-year-old male with a history of thymic cancer with left femur pain. Evaluate for bony lesion. There is thickening and heterogeneity of the cortex of the left femoral diaphysis which likely reflects periosteal reaction as seen on recent radiographs, which is nonspecific but perhaps due to hypertrophic osteoarthropathy. We suspect a similar process affects the right femur as seen on the large field-of-view coronal images. There is avascular necrosis of the left femoral head appearing similar to the prior pelvic MRI study from February 26 of 2015. There is patchy intermediate signal intensity within the medullary space of the left femur that appears similar to that seen on the right and likely represents residual or reconverted red marrow. There is a 1.5 cm ovoid focus of low signal intensity on T1-weighted imaging and high signal intensity on T2-weighted imaging within the subtrochanteric left femur that we suspect also reflects more concentrated red marrow although we cannot entirely exclude the possibility of a small metastatic focus. A presumed metastatic focus is again noted within the posterior column of the right acetabulum, appearing similar to that seen on the prior pelvis MRI. There is avascular necrosis of the right femoral head also appearing similar to the prior study. There is metallic susceptibility artifact within the distal right femur and proximal tibia presumably related to prior ACL repair. There are small bilateral knee and hip joint effusions.The musculature of the thigh appears atrophic. There is relatively increased signal intensity of the vastus medialis, lateralis and intermedius muscles on fluid sensitive sequences that is nonspecific and could reflect mild edema or subacute atrophy. There are similar findings, suggested on the large field-of-view coronal sequence, affecting the contralateral side, which appear less pronounced. There is also mild edema within the soft tissues along the adductor musculature of the hips bilaterally as well as confluent edema and/or crescentic fluid between the IT band and underlying proximal quadriceps musculature. This is also noted, to a lesser degree, on the contralateral side. We see no masslike collection to suggest abscess formation. There is reticulation of the subcutaneous fat along the lateral aspect of the hips suggestive of mild edema.
1. Cortical thickening and heterogeneity of the cortex of the femoral diaphysis is nonspecific but may reflect hypertrophic osteoarthropathy and corresponds to the findings seen on prior radiographs.2. Avascular necrosis of the femoral heads, appearing similar to the prior study.3. Heterogeneity of the medullary space of the proximal femora bilaterally is favored to represent residual reconverted red marrow. A slightly more prominent focus in the subtrochanteric left femur may also represent reconverted red marrow although a small metastatic lesion cannot be excluded. Further evaluation with a skeletal scintigraphic examination could be considered if clinically warranted.4. Right acetabular metastatic focus, appearing similar to the prior study.5. Muscular atrophy and nonspecific inflammatory changes of the soft tissues as described above.