Prostate cancer remains a major health concern for the male population. Detection and primary diagnosis of prostate cancer are based on digital rectal examination, serum prostate-specific antigen levels, and transrectal ultrasound (TRUS)-guided random biopsy. A substantial proportion of biopsy-detectable prostate cancer occurs in men with "normal" PSA levels and negative DRE. At low prostate specific antigen (PSA) the indication for prostate biopsy is usually an abnormal digital rectal examination. In the study by Schroder et.al., approximately half of the tumors missed with PSA 0 to 4 ng/ml, had aggressive characteristics and were organ confined.
In another study by Lee et.al. showed that patients in the low PSA group had significantly smaller prostates and lower PSA density . The rate of cancer detection was 16.7% (24 of 144) in the low PSA group and 23.7% (145 of 611) in the intermediate PSA group. 2
The gold standard for prostate cancer diagnosis is true cut biopsy guided by transrectal ultrasound.
The study of Maricic et.al. showed prostate cancer is mostly found in the peripheral zone. Smaller tumors are hypoechoic and bigger tumors are hyperechoic. Prostate cancer lesions are impossible to differentiate from chronic prostatitis only by TRUS. Implementation of PSA has significantly decrease sensitivity, accuracy and negative predictive value of TRUS in prostate cancer detection.
An accurate early localization of prostate cancer, permitting efficient use of modern focal therapies, is currently hampered by a lack of imaging methods. Contrast-enhanced Doppler allows reliable differentiation of prostate cancer and normal prostate tissue with a high sensitivity in patients with previous negative biopsy and fewer artifacts than power Doppler images, thus providing a good basis for targeted prostate biopsy instead of systematic biopsy.
Transrectal Ultrasound (TRUS) has only moderate accuracy in the detection of prostate carcinoma, but is very useful in the estimation of prostate volume and thus calculation of PSA-density.
More refined measurements of prostate pathology have been employed over the last decades. There is high diagnostic value of strain index (SI) for transrectal real-time tissue elastography (TRTE) on differentiating malignant from benign lesions in the prostate peripheral zone.6 Sonoelastography (SEG) is a noninvasive ultrasound (US) method able to differentiate tissues according to their stiffness and improve prostate cancer detection, alone or associated with other US methods.
The role of ultrasound in combination with PSA in the diagnosis of prostate cancer has been studied in several studies. However, the direct correlation of specific sonographic features such as volume and PSA has been unclear even during the monitoring of patients' response to radiation therapy.
Performing biopsy in all men with a serum prostate specific antigen (PSA) at lower cut-off values (i.e. 3 to 3.9 ng./ml) increases the sensitivity of prostate cancer screening compared with a PSA cutoff of 4 ng./ml. but decreases specificity and may contribute to over diagnosis. In the absence of other significant findings like an abnormal digital rectal examination, the rationale of doing real-time sonography role is also unclear.
The present study aims to identify specific sonographic features of prostatic masses (volume, PSA density and other descriptors) whose PSA levels are below the reference range set for normality and determine the prevalence of malignancy in this subgroup of patients.