What is the recently described sign reflecting the unique pathological feature of mycetoma?
The dot-in-circle sign is a recently described sign reflecting the unique pathological feature of mycetoma. It is seen as a tiny hypointense focus within high-intensity spherical lesions. This sign was described on T2-weighted, STIR, and T1-weighted fat-saturated gadolinium-enhanced images.
How will you differentiate between the tuberculous and eumycetoma involvement of the foot on MRI Scan?
MRI findings of tuberculous infection include synovial thickening around the tendons and synovial fluid collections that may contain small low-signal-intensity foci in the tendon sheath or bursa (rice bodies) caused by caseous material or debris. These features help to differentiate tuberculous infection from other infections.
Selected images from an MRI of left foot demonstrate a soft tissue mass involving the left foot, the mass showed conglomerate areas of multiple, discrete, small 2–5 mm round hyperintense lesions, which were separated by a low-signal-intensity rim and central hypointense dot infiltrating the adjacent muscles.
T2-weighted MRI revealed diffuse hyperintensity involving the subcutaneous tissue, muscles, and intermuscular fascial planes, with multiple pockets of fluid collections with overlying skin ulceration. Also, multiple small discrete spherical hyperintense lesions were noted, which were divided by a network of low-intensity soft tissue. In the centre of some of these lesions, there was a tiny hypointense focus, resulting in the dot-in-circle sign. Small conglomerated low-intensity foci and micro-abscesses were also seen at other sites.