Study On The Elastographic Characteristics Of Prostate Peripheral Zone Lesions And Benign Prostatic Hyperplasia

Objective1. To evaluate the contribution of TRTE on the differential diagnosis of prostate peripheral zone lesions.2. To investigate the relationship between elastogram of prostatic transitional zone and the international prostatic symptoms scores (IPSS) in patients who had benign prostatic hyperplasia (BPH).Materials and Methods1.171 patients who were suspected of having prostate peripheral zone cancer and were scheduled for biopsy underwent transrectal ultrasonography (TRUS) and TRTE examinations and digital rectal examination (DRE). Their prostate-specific antigen (PSA) and magnetic resonance imaging (MRI) findings were recorded. Then the TRTE examination was performed, and the strain patterns of the lesions were classified into five grades. The quantitative analysis by TRTE was also performed. The SI of total lesions (ASI) and peak elasticity in lesion (PSI) were calculated, respectively. The findings of TRTE were compared with other methods and pathological results.2.56 patients who have been proved BPH by the biopsy and/ or surgical operation were included in this study. IPSS of patients were done before the biopsy. Then the TRUS examination was performed, and the prostate was measured. The toal prostate volume (TPV), transitional zone volume (TZV) and transitional zone index (TZI) were calculated according to the values obtained by measuring. After that, the TRTE examination was performed, and the elastography of transitional zone was observed. The relationship among the prostatic volume parameters, elastography of transitional zone and IPSS of patients was analyzed. Results1. Study of elastography in the differential diagnosis of prostate peripheral zone lesions.(1) When a cutoff point of strain pattern gradeⅢwas used, the diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value were 92.3%,77.1%,83.8%,75.9% and 92.8% respectively, for TRTE only. They were 80%,88%,84.4%,83.9% and 84.9% for the combination of TRUS and TRTE. A positive linear tendency of strain pattern and Gleason scores was observed in gradesⅢ-Ⅴ. The detection rate of cancer by TRTE is better in the apex areas (50.6%) than base (16.1%) and mid-gland areas (45.6%)(2) It was concluded that the area under ROC curve of ASI and PSI were 0.62 (P=0.06) and 0.90 (P=0.00) respectively for the differential diagnosis of prostate peripheral lesions. The average PSI of malignant lesions (29.97±15.58) was greater than the benign ones (7.79±8.75). When a cutoff point of 17.44 was used, PSI had 74.5% sensitivity,83.3% specificity.(3) There was no correlation between the diagnostic consistency of TRTE with pathology and the serum total PSA level (P>0.05). The diagnostic sensitivity of TRTE decreased when the prostate volume increases. The diagnostic specificity of TRTE was greater than MRI in the patients with the soft or moderate nodules examined by DRE (P<0.05), and the diagnostic sensitivity of TRTE was higher for high-grade tumors than those for low-grade tumors (P<0.05).2. The relationship between elastogram of prostatic transitional zone and the IPSS in patients who had BPH Postitive correlation was observed between the TPV, TZV, TZI and the lower urinary tract symptom of patient, and the correlation coefficient were respectively 0.55,0.64 and 0.65; There was significant difference of TPV, TZV, TZI in soft group and stiff group by TRTE (P<0.05). There was significant difference of two kinds of elastograms in the grades of symptoms (U=4.326 >2.58, P<0.01). When a cutoff point of 8.5 was used, IPSS had 75% sensitivity,91.7% specificity.Conclusion(1) This study shows the significant contribution of strain pattern combined with TRUS on haracterization of prostate peripheral zone lesions.(2) PSI is helpful to the diagnosis of prostate peripheral zone lesions.(3) TRTE may provide helpful information for the clinical diagnosis when combined with other examination methods of prostate (PSA, DRE and MRI).(4) Transitional zone stiffness showed by TRTE was correlated with the IPSS of patient, and TRTE could be a new method to find the cause of patient's lower urinary tract symptom.