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. 2016 Jun 4;11(3):201–206. doi: 10.1016/j.radcr.2016.05.002

Table 2.

Reported MR features for selected malignant foot lesions.

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.