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Diagnostic performance of diffusion-weighted MRI in the detection of nonpalpable undescended testes: comparison with conventional MRI and surgical findings.

OBJECTIVE
The aim of this feasibility study was to evaluate the role of diffusion-weighted MRI in the evaluation of nonpalpable undescended testes.


MATERIALS AND METHODS
Thirty-six boys with undescended testes underwent preoperative abdominal and pelvic MRI to identify the location of the testes. MRI included free-breathing diffusion-weighted imaging (DWI) with b values of 50, 400, and 800 s/mm(2), a T1-weighted turbo spin-echo sequence, and a T2-weighted fat-suppressed turbo spin-echo sequence. After laparoscopic examinations, two observers independently reviewed the preoperative images. The DW images alone were reviewed first, followed by the conventional MR images alone and the conventional MR and the DW images together. The laparoscopic and MRI findings were compared. Sensitivity, specificity, and accuracy in the identification of nonpalpable undescended testes were calculated for DWI, conventional MRI, and the combination of DWI and conventional MRI.


RESULTS
The combination of DWI and conventional MRI was the most sensitive and most accurate technique. Observer 1 found 31 undescended testes, and observer 2, 30 testes with this technique. Sensitivity was 0.91 and 0.88 for observers 1 and 2, and accuracy was 0.92 and 0.86. With DWI alone, observer 1 located 30 testes, and observer 2, 28 testes (sensitivity, 0.88 and 0.82; accuracy, 0.86 and 0.81). Using conventional MRI alone, both observers located 29 testes (sensitivity, 0.85; accuracy, 0.86 and 0.84). The accuracy of locating testes was superior with the combination of DWI and conventional MRI for both observers (accuracy, 0.92 and 0.86). An intraabdominal atrophic testis managed by laparoscopic orchiectomy was found by neither observer with DWI or with conventional MRI.


CONCLUSION
Use of DWI with a high b value yields information that complements conventional MRI findings, improving identification and location of nonpalpable undescended testes. We recommend the use of conventional MRI in addition to DWI to increase the preoperative sensitivity and accuracy of identifying and locating nonpalpable testes.