Elastographic Strain Index in the Evaluation of Focal Lesions Detected With Transrectal Sonography of the Prostate Gland

OBJECTIVES: The purpose of this study was to evaluate the value of elastography in evaluating focal lesions detected by transrectal sonography and to suggest a reference strain index. METHODS: Sixty-nine patients with focal lesions on transrectal sonography were referred to our department for prostate biopsy. Focal lesions were classified as either highly or less suspicious lesions by our criteria. A strain index from elastography was calculated for the focal lesions. Systematic 12-core randomized biopsies plus 2 targeted biopsies were performed. The mean strain indices for malignant and benign focal lesions were compared, and a cutoff strain index was attained to maximize the sensitivity and specificity for prostate cancer. Strain indices were correlated with Gleason scores. RESULTS: The mean strain index ± SD for malignant focal lesions (3.26 ± 1.77) was significantly higher than that for benign focal lesions (2.16 ± 1.52; P = .008). The sensitivity, specificity, and area under the receiver operating characteristic curve for diagnosing cancer were 66.7%, 71.1%, and 0.701, respectively, at a strain index cutoff value of greater than 2.4. The strain index showed a moderate linear correlation with the Gleason score (r = 0.441; P = .013). CONCLUSIONS: Any focal lesion on transrectal sonography with a strain index of greater than 2.4 is at risk for prostate cancer.