Summary Background: The aim of this study was to describe the gray-scale and color Doppler ultrasonography (US) and magnetic resonance (MR) imaging features of testicular adrenal rest tumors (TART) in patients with congenital adrenal hyperplasia. Material/Methods Forty-one patients with congenital adrenal hyperplasia were evaluated by gray-scale and color Doppler ultrasonography. Totally eighteen adrenal rest tumors in 9 patients were diagnosed TART on US and MR imaging. Gray-scale and color Doppler US and MR findings of the patients were documented. Results: A total of eighteen masses were evaluated in nine patients. The mean age of these patients was 14.3±4.5 (range 10.1–23.3) years. US revealed hypoechoic lesions around the mediastinum testis with hypervascularity dispersing in ten patients and hypovascularity in two patients. In six patients, the lesions were hyperechoic with poor vascularity. Lesions exhibited homogeneous (n=8) and heterogeneous (n=10). Testicular microlithiasis was present in 4 of 9 patients with TART. Doppler ultrasound showed normal testicular vessels passing through the mass which were undisturbed, not displaced and not change in caliber. MRI features were the following: all lesions were hypointense on T2- and hyperintense (n=12) and isointense (n=6) on T1-weighted images. All masses revealed homogeneous contrast enhancement on postcontrast T1-weighted images. Conclusions: Ultrasonography and MRI are good methods for detecting and monitoring TART. US is the first preferable modality because it is quick and cheap than MRI. Bilateral mostly hypoechoic lesions depicted around the mediastinum testis with no mass effect is highly suggestive for the diagnosis of testicular adrenal rest tissues on ultrasonography. Normal testicular vessels coursing through the lesions undisturbed and not change in caliber is described specific for this kind of tumors
