Diagnostic value of qualitative and strain ratio elastography in the differential diagnosis of non-palpable testicular lesions

Abstract

The purpose of this study was to evaluate prospectively the accuracy of qualitative and strain ratio elastography (SE) in the differential diagnosis of non-palpable testicular lesions. The local review board approved the protocol and all patients gave their consent. One hundred and six patients with non-palpable testicular lesions were consecutively enrolled. Baseline ultrasonography (US) and SE were correlated with clinical and histological features and ROC curves developed for diagnostic accuracy. The non-palpable lesions were all ≤1.5 cm; 37/106 (34.9%) were malignant, 38 (35.9%) were benign, and 31 (29.2%) were non-neoplastic. Independent risk factors for malignancy were as follows: size (OR 17.788; p = 0.002), microlithiasis (OR 17.673, p < 0.001), intralesional vascularization (OR 9.207, p = 0.006), and hypoechogenicity (OR, 11.509, p = 0.036). Baseline US had 89.2% sensitivity (95% CI 74.6-97.0) and 85.5% specificity (95% CI 75.0-92.8) in identifying malignancies, and 94.6% sensitivity (95% CI 86.9-98.5) and 87.1% specificity (95% CI 70.2-96.4) in discriminating neoplasms from non-neoplastic lesions. An elasticity score (ES) of 3 out of 3 (ES3, maximum hardness) was recorded in 30/37 (81.1%) malignant lesions (p < 0.001). An intermediate score of 2 (ES2) was recorded in 19/38 (36.8%) benign neoplastic lesions and in 22/31 (71%) non-neoplastic lesions (p = 0.005 and p = 0.001 vs. malignancies). None of the non-neoplastic lesions scored ES3. Logistic regression analysis revealed a significant association between ES3 and malignancy (χ² = 42.212, p < 0.001). ES1 and ES2 were predictors of benignity (p < 0.01). Overall, SE was 81.8% sensitive (95% CI 64.8-92.0) and 79.1% specific (95% CI 68.3-88.4) in identifying malignancies, and 58.6% sensitive (95% CI 46.7-69.9) and 100% specific (95% CI 88.8-100) in discriminating non-neoplastic lesions. Strain ratio measurement did not improve the accuracy of qualitative elastography. Strain ratio measurement offers no improvement over elastographic qualitative assessment of testicular lesions; testicular SE may support conventional US in identifying non-neoplastic lesions when findings are controversial, but its added value in clinical practice remains to be proven.

Keywords: Leydig cell tumor; male infertility; scrotal ultrasound; seminoma; strain elastography; testicular cancer.