Differential diagnosis of fibroma of tendon sheath and giant cell tumor of tendon sheath in the finger using signal intensity on T2 magnetic resonance imaging.

Background: The differential diagnosis of fibroma of tendon sheath (FTS) and giant cell tumor of tendon sheath (GCTTS) on the basis of clinical and radiographic characteristics remains difficult.

Purpose: To evaluate the quantitative measurement of signal intensity (SI) obtained by magnetic resonance imaging (MRI) for the differential diagnosis of FTS and GCTTS in just the finger.

Material And Methods: We retrospectively identified patients with FTS (n = 6) and GCTTS (n = 22) of the finger who were treated at our hospitals between April 2011 and August 2019. Two researchers independently reviewed the MRIs and measured the regions of interest (ROIs) in the tumor and flexor tendon from the same image. The SI ratio obtained for the tumor and tendon ROIs was measured and compared using receiver-operating characteristic curve analyses. Sensitivity and specificity analyses were performed.

Results: The SI ratios (mean ± SD) of FTS and GCTTS were 1.83 ± 0.64 and 6.34 ± 3.16 for researcher 1 and 1.82 ± 0.60 and 6.10 ± 3.22 for researcher 2, respectively. The areas under the curve were 0.970 and 0.970 for researchers 1 and 2, respectively. The cut-off values of the SI ratio as determined by researchers 1 and 2 for differentiating FTS from GCTTS were 3.00 and 3.00, respectively (sensitivity = 95.5%, specificity = 100%).

Conclusions: The SI ratio is useful for differentiating FTS from GCTTS independent of a combination of tumor signal and shape.