Transrectal Real-time Tissue Elastography - An Effective Way to Distinguish Benign and Malignant Prostate Tumors

Background: To investigate the relationship between extracellular matrix parameters and texture of prostatic lesions evaluated by transrectal real-time tissue elastography (TRTE). Methods: 120 patients suspicious for prostate cancer underwent TRTE. Targeted biopsies were carried out after 12-core systematic biopsy. Epithelia were stained with hematoxylin-eosin, and Victoria blue and Ponceau S were used to stain elastic-collagen fibers, and picric acid-sirius red for visualization of collagen type I (Col1) and III (Col3). Smooth muscles were visualized by immunohistochemistry. All image analyses were performed in a blind manner using Image Pro Plus 6.0, and the area ratios of epithelium, elastic fibers, collagen fibers and Col1/Col3 were determined. Results: 42 patients with typical elastograms were included in the final data analysis. Significant differences were detected between the benign and malignant groups in the area ratios of epithelium (P = 0.01), smooth muscles and Col1/Col3 (P = 0.04, P = 0.02, respectively). There were no significant differences in the area ratios of epithelium, smooth muscle and elastic fibers between the stiff and soft lesion groups. The area ratio of Col1 was ($0.05{\pm}0.03$) in the stiff group, and ($0.02{\pm}0.01$) in the soft group (P= 0.00). However, the area ratio of Col3 was ($0.03{\pm}0.02$) in the stiff group, and ($0.05{\pm}0.04$) in the soft group (P = 0.16). Col1/Col3 in the stiff group ($1.99{\pm}1.59$) was greater than in the soft group ($0.71{\pm}0.64$) (P = 0.01). Conclusions: Tissue hardness of prostatic tumors was mainly dependent on the Col1 content, Col1/Col3 being higher in malignant than in benign lesions, so the prostate tissue texture can be used as a target for distinguishing between the two with TRTE.