Figure 5a. Large bone sarcoidosis in a 53-year-old woman with bilateral heel pain. The patient’s medical history was unknown. (a) Sagittal T1-weighted MR image (450/10) demonstrates a round, low-signal-intensity lesion that involves the plantar aspect of the calcaneus. Biopsy of a lesion of the contralateral calcaneus (not shown) revealed noncaseating granulomas and led to further clinical evaluation, results of which confirmed systemic sarcoidosis. (b) Lateral radiograph of the ankle reveals a faint area of increased opacity in the area of the lesion seen at MR imaging, with no radiographic evidence of trabecular or cortical disruption. The radiograph was interpreted as normal. (c) Sagittal fat-saturated T1-weighted MR image (650/8) obtained after the intravenous administration of gadopentetate dimeglumine shows an indistinctly marginated area of enhancement with a central area of spared marrow in the contralateral calcaneus (arrow).