Non-palpable incidentally found testicular tumors: Differentiation between benign, malignant, and burned-out tumors using dynamic contrast-enhanced MRI.

Purpose: To evaluate qualitative, semi-quantitative, and quantitative parameters obtained by dynamic contrast-enhanced (DCE)-MRI for the characterization of histologically proven, non-palpable, incidentally found intratesticular tumors.

Materials And Methods: From 2006 to 2014, we included men with non-palpable, incidentally found testicular tumors on ultrasound, normal tumoral marker levels,referred for surgery. DCE-MRI data were analyzed retrospectively and independently by two radiologists blinded to the histological diagnosis. The visual enhancement patterns, time-signal intensity curves, shape of the curves (type 0-3), maximal relative enhancement (Peak), initial enhancement slope (IS), time to peak (TTP), as well as transfer constants Ktrans and Kep were compared between the tumors. The interobserver correlation was evaluated. Receiver Operating Characteristic (ROC) curves and areas under the curve (AUC) were extracted.

Results: Thirty-one patients (mean age of 37.3 years) were included. Tumor mean size was 1.2±0.77 cm (min=0.3cm, max=2.8cm). Regarding the histology results, three groups were defined: Twelve stromal "benign tumors" (BT) exhibited more type 2 and type 3 curves than 12 "malignant tumors" (MT) and 7 "burned-out tumors" (BOT) (p<0.0001). BT had a higher peak (96 vs. 54 and 17%), shorter TTP (215 vs. 412 and 692 sec), higher IS (73 vs. 12 and 2 arbitrary units), higher Ktrans (255 vs. 88 and 14min*1000) and higher Kep (554 vs. 159 and 48min*1000) than MT and BOT, respectively (p<0.0001, p=0.0003, p<0.0001, p<0.0001 and p<0.0001, respectively). The agreement coefficient values and the AUC extracted after gathering MT with BOT varied from 0.83 to 0.96 and from 0.868 to 0.978, respectively.

Conclusion: DCE-MRI may assist in differentiating between benign intratesticular stromal tumors,malignant and burned-out tumors.