Evaluation of bladder outlet obstruction in benign prostatic hyperplasia patients using shear wave sonoelastography: a prospective study

Abstract

Objective To evaluate the correlation between the elastic modulus of prostate and the degree of bladder outlet obstruction (BOO) in benign prostatic hyperplasia (BPH) patients in order to build a new non-invasive diagnostic indicator for BOO.Methods From november 2011 to November 2012,a total of 34 BPH patients were enrolled in this prospective study.Clinical information of the patients including age,international prostate symptom score (IPSS) and quality of life (QOL) were collected.The morphological features of prostate including total prostate volume,transitaion zone volume and transition zone index were detected by transrectal ultrasound (US),and prostate elastic modulus was detected using shear wave sonoelastograhy.After US examination,urodynamic study was performed by the urologist and pressure-flow curves were used to determine the diagnosis and the degree of bladder outlet obstruction.The correlation of prostate elastic modulus and other features including clinical information,morphological features and urodynamic features with the degree of bladder outlet obstruction were evaluated.ROC curves were evaluated.The feature with the best diagnostic performance was obtained,the diagnostic values of which were calculated.Results 9 patients had no BOO,with the average prostate elastic modulus of (27.3±5.0) kPa; 12 patients had mild to moderate BOO,with the average prostate elastic modulus of (30.7±2.8) kPa; 13 patients had severe BOO,with the average prostate elastic modulus of (34.7±2.4) kPa.The prostate elastic modulus had higher correlation coefficient with the degree of bladder outlet obstruction than the other features (r =0.754,P=0.000).It also had the highest AUC of 0.853 (95％CI 0.720-0.986).At a cutoffof 31.65 kPa,the sensitivity,specificity and accuracy of the prostate elastic modulus for the diagnosis of BOO were 72％,90％and 81％ respectively.Conclusion The prostate elastic modulus is highly correlated with the degree of bladder outlet obstruction,which might serve as a novel,promising indicator to evaluate BOO in BPH patients. Key words: Benign prostatic hyperplasia; Bladder outlet obstruction; Elastic modulus; Shear wave sonoelastography; Prospective studies