Table 2.
Lesion type | T1-weighted intensity | T2-weighted intensity | Contrast enhancement | Other MR features |
---|---|---|---|---|
Synocial sarcoma | Inhomogenous low-to-intermediate T1 signal [8], [13] | Hyperintense, isointense, and hypointense T2 signal [13] | Intense enhancement where tissues remain viable [8], [13] | Relatively well-defined lesions typically found intermuscularly [5], with peritendinous growth [1]. May demonstrate infiltrative growth, and may exhibit septated areas of hemorrhage and necrosis [8], [13]. |
Clear-cell carcinoma | Increased signal on T1 relative to muscle [8] | Variable T2 signal [8] | Strong and diffuse enhancement [10] | Preponderance for heels, of young to middle aged adults [10]. Often well-defined and relatively homogenous on MR 10; shortening of T1 and T2 relaxation times may be seen where melanin is present [13]. |
Deep fibromatosis | Low-to-intermediate T1 signal [8] | High T2 signal [8] | Moderate-to-marked enhancement [8], [13] | Aggressive growth pattern, no metastases, patients typically in their third decade [8], [13]. Characteristic intralesional bands of low signal that do not enhance are seen on all pulse sequences [8], [13]. |
Liposarcoma | High T1 signal for lipomatous tumor portions and isointense to muscle for nonlipomatous portions [10] | T2 intensities higher than fat for nonlipomatous tumor portions [10] | — | MR appearance varies throughout tumor reflecting inclusion of lipomatous and nonlipomatous portions. The degree of lipomatous tumor can change with the degree of differentiation [10]. |
Plexiform fibrohistiocytic tumor | Low-to-intermediate T1 signal [10] | Low-to-intermediate T2 signal [10] | — | Appear in younger patients, as if composed of small nodules of tumor that rarely metastasize [10]. |
Extraskeletal chondrosarcoma | Low-to-isointense T1 signal [10] | Variable T2 signal but usually higher than muscle [10] | Heterogenous enhancement [10] | Appear as extraskeletal cartilage. More common in middle aged patients though rare in feet [10]. |
Surfers' knots do not exhibit aggressive features such as joint erosions, infiltration of adjacent joints or other structures, marrow signal abnormalities, or marked contrast enhancement.