Shear Wave Ultrasound Elastography of the Prostate

Abstract

This prospective study was to evaluate shear wave elastography (SWE) in the detection of prostate cancer (PC). Patients scheduled for a transrectal ultrasound (TRUS) biopsy of the prostate because of elevated prostate-specific antigen levels or abnormal digital rectal examination result underwent a standard TRUS and SWE. A second TRUS examination and sextant biopsy by a second physician blinded to SWE results was then performed. Pathologic result was reviewed, and sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated. A total of 53 patients (318 sextants) participated in the study. Mean age was 64.2 years (range, 53-79 years). A total of 26 foci of PC were detected in 11 patients (20.7%). On the basis of the receiver operating characteristic curve, a value of 37 kPa was used as the cutoff between benign and malignant. This produced a sensitivity of 96.2% (25/26), a specificity of 96.2% (281/292), a PPV of 69.4% (25/36), and an NPV of 99.6% (281/282). Six (55%) of 11 false-positive samples were secondary to benign calcifications. The Young modulus of PC ranged from 30 to 110 kPa (mean [SD], 58.0 [20.7] kPa). At the patient level, if a cutoff of 40 kPa was used, all PCs would have been detected, and the positive biopsy rate would be 11 (50%) of 22 compared to 11 (20.8%) of 53 without SWE--a 140% increase in the positive biopsy rate. Shear wave elastography has a high sensitivity, specificity, PPV, and NPV for the detection of PC. With a high PPV, patients with elevated prostate-specific antigen levels or abnormal results in the digital rectal examination and negative SWE may not require biopsy. This could significantly reduce the negative biopsy rate in PC detection.