Ultrasound-guided four quadrant biopsy of the prostate: efficacy in the diagnosis of isoechoic cancer

Current Impact of Transrectal Ultrasonography in Prostate Cancer Diagnosis

Aims

We evaluate the diagnostic accuracy of transrectal prostate ultrasonography (TRUS) in prostate cancer (PCa) diagnosis in a group of patients who underwent prostate biopsy in 2008.

Material and Methods

100 patients (mean age 65 years) underwent transrectal prostate biopsy at our center. Indications to biopsy were: suspected malignancy at rectal examination or increase of total PSA and/or PSA velocity and/or PSA density and/or low percentage of free PSA. 10–12 biopsies and additional ones in case of suspected ecographic images in every patient were carried out. We classified the ecographic aspects as: highly suggestive for heteroplasia (focal or widespread hypoechoic area in the peripheral zone), weakly suggestive (small hypoechoic focal alterations), and isohecoic areas.

Results

At ultrasound examination, highly suggestive images were found in 20 patients, weakly suggestive images in 39 patients, and isoechoic images in 41 patients. PCa was diagnosed in 45 patients. 40% of cancers (18 pts) appeared as highly suggestive hypoechoic images, 31% (14 pts) as weakly suggestive, and 29% (13 pts) as isoechoic. 32% was the positive predictive value of isoechoic areas biopsies, 90% of highly suggestive hypoechoic images, and 36% of weakly suggestive images. In the last ones, the diagnosis was often coincidental, i.e. in the opposite lobe, or in a different sextant of the same lobe (serendipity). Detection rate was 60% for prostate volumes ≤50 cc and 24% for volumes >50 cc.

Discussion

The result analysis allowed us to formulate the following considerations: - 60% of currently diagnosed PCa are not detectable by ultrasonography, or there are aspecific ecographic findings - 40% of cancers are detectable by ultrasonography with specific ecographic findings - The clinical value of the hypoechoic focal alterations is similar to isoechoic ones - Detection rate is positively influenced by prostate volume.

Conclusions

The study of hypoechoic and isoechoic bioptised areas shows a significant difference in TRUS accuracy in prostate cancer diagnosis. In this set of patients, prostate volume and transrectal ultrasonographic findings proved to be the most informative variables about PCa risk at the moment of first biopsy at any age.

Value of contrast-enhanced ultrasound and elastography in imaging of prostate cancer

PURPOSE OF REVIEW

Prostate cancer is the most commonly diagnosed malignancy in men. Gray-scale ultrasound-guided systematic biopsy is the standard of care for prostate cancer detection in men with an elevated prostate-specific antigen or an abnormal digital rectal examination. Systematic biopsy may miss up to 35% of clinically relevant cancers. Color and power Doppler ultrasound, ultrasound contrast agents, and elastography have and will dramatically change the role of ultrasound in prostate cancer diagnosis.

RECENT FINDINGS

Several reports have demonstrated that contrast-enhanced ultrasound investigations of the blood flow of the prostate allow for prostate cancer visualization and therefore, for targeted biopsies. Comparisons between systematic and contrast-enhanced ultrasound-targeted biopsies have shown that the targeted approach detects more cancers with a lower number of biopsy cores. Furthermore, contrast-enhanced ultrasound has been shown to detect cancers with higher Gleason scores compared with the systematic approach, which seems to improve prostate cancer grading. In addition, elastography is a new ultrasound technique that allows for the assessment of tissue elasticity.

SUMMARY

Contrast-enhanced ultrasound and elastography improve prostate cancer detection and may be useful for prostate cancer grading and staging. Future clinical trials will be needed to determine the promise of these new advances for ultrasound of the prostate evolving into clinical applications.

Prostate ultrasound--for urologists only?

The value of ultrasound (US) in the diagnosis of prostate cancer has dramatically increased in the past decade. This is mainly related to the increasing incidence of prostate cancer, the most common cancer in men and one of the most important causes of death from cancer in men. The value of conventional gray-scale US for prostate cancer detection has been extensively investigated, and has shown a low sensitivity and specificity. Therefore conventional gray-scale US is mainly used by urologists for guiding systematic prostate biopsies. With the development of new US techniques, such as color and power Doppler US, and the introduction of US contrast agents, the role of US for prostate cancer detection has dramatically changed. Advances in US techniques were introduced to further increase the value of US contrast agents. Although most of these developments in US techniques, which use the interaction of the contrast agent with the transmitted US waves, are very sensitive for the detection of microbubbles, they are mostly unexplored, in particular for prostate applications. Early reports of contrast-enhanced US investigations of blood flow of the prostate have shown that contrast-enhanced US adds important information to the conventional gray-scale US technique. Furthermore, elastography or ‘strain imaging’ seems to have great potential in prostate cancer detection. Since these new advances in US are very sophisticated and need a long learning curve, radiologists, who are overall better trained with these new US techniques, will play a more important role in prostate cancer diagnosis. Current trends show that these new US techniques may allow for targeted biopsies and therefore replace the current ‘gold standard’ for prostate cancer detection—the systematic biopsy. Consequently the use of these new US techniques for the detection and clinical staging of prostate cancer is promising. However, future clinical trials will be needed to determine if the promise of these new US advances of the prostate evolves into clinical application.

Advances in ultrasound for the detection of prostate cancer

The introduction of ultrasound (US) microbubble contrast agents has dramatically expanded the possibilities for US detection of prostate cancer. Recent advances in US technology have increased the value of US contrast agents. Many newer US techniques, which are quite sensitive for detection of microbubbles, are yet to be explored for prostate applications. A critical evaluation of the current status of transrectal US imaging for the detection of prostate cancer and background information for US contrast agents and imaging techniques are presented. Early results have demonstrated the feasibility of US contrast agents to enhance US imaging of prostatic disease. The application of US contrast agents for the detection and clinical staging of prostate cancer is promising. Future clinical trials are needed to determine whether the promise of contrast-enhanced US of the prostate will evolve into widespread clinical application.

Biopsy protocol stability in a three-dimensional model of prostate cancer: changes in cancer yield after adjustment of biopsy positions

OBJECTIVES

Transrectal ultrasound-guided prostate biopsies are often taken according to a systematic, standardized schedule. The diagnostic stability of this system was evaluated by moving the biopsies in a three-dimensional (3D) model.

METHODS

A computerized 3D reconstruction was made from each of 75 radical prostatectomy specimens. Simulated core biopsies imitated a standardized 10-biopsy protocol, including sextant biopsies. In total, 30,000 biopsies were generated by moving the standardized biopsies 1, 2, 3, and 4 mm (parallel needle shifts) or 5 degrees, 10 degrees, 15 degrees, and 20 degrees(rotation of the needle tip) in a random direction.

RESULTS

The diagnosis of the individual biopsy changed from cancer to benign or vice versa in 4.9% to 1 5.7% after 1 to 4-mm parallel needle shifts and 2.0% to 7.5% after 5 degrees to 20 degrees rotations. The corresponding figures for the final diagnosis of the 10-biopsy set were 0.8% to 9.6% and 0.5% to 3.2%. Transition zone biopsies containing cancer changed to benign more often than the other biopsies (P <0.001). Parallel needle shifts of 2 mm changed the diagnosis more often than the 15 degrees rotation (9.4% and 5.9%, respectively, P <0.001), although conveying the same overall needle shift.

CONCLUSIONS

The cancer yield of prostate biopsies is influenced even by small changes in needle positions. The transition zone biopsies are most likely to change from cancer to benign when moved. Changing the insertion point of the needle has a higher impact on cancer yield than rotating the tip.

Prostate imaging may not be necessary in nonpalpable carcinoma of the prostate

OBJECTIVES

Stage T1c carcinoma of the prostate is defined as a nonpalpable carcinoma (NPC-P) that is not visible by imaging and is identified by needle biopsy performed because of elevated prostate-specific antigen (PSA) concentrations. The purpose of this study was to define the incidence of normal findings on transrectal ultrasound (TRUS) and/or endorectal coil magnetic resonance imaging (EMRI) among patients with NPC-P, as well as to investigate the value of differentiating patients with Stage T1c disease from all other patients with NPC-P.

METHODS

The records of 2211 patients diagnosed with prostate carcinoma between 1988 and 1995 were reviewed to identify 291 men with NPC-P. TRUS and EMRI reports were analyzed with regard to the presence and laterality of hypoechoic nodules or low-signal areas reported on T2-weighted images, respectively. Ninety percent of patients (n = 262) had at least six prostate biopsies, 185 patients (64%) underwent both TRUS and EMRI, 224 (77%) had TRUS, and 251 (86%) had an EMRI study.

RESULTS

Results were considered normal in 101 (47%) of 214 patients undergoing TRUS, in 58 (23%) of 249 undergoing EMRI, and in 22 (12%) of 185 undergoing both TRUS and EMRI. For the side of the prostate with positive biopsy results, correlation with imaging abnormalities was better for EMRI than for TRUS (39% versus 24%). There was no significant difference in mean PSA value, distribution of Gleason score, or unilateral versus bilateral positive biopsy results among patients with normal versus abnormal findings on both TRUS and EMRI.

CONCLUSIONS

(1) Only 12% of men with NPC-P have no TRUS or EMRI abnormalities, fulfilling the criteria for Stage T1c prostate carcinoma. (2) Those patients with Stage T1c disease do not differ from patients with NPC-P up-staged by TRUS or EMRI, with regard to pretreatment PSA levels, Gleason scores, and the probability of having bilateral rather than unilateral positive biopsy results. (3) The value of classifying patients with NPC-P into Stage T1c versus higher stages of prostate carcinoma on the basis of imaging should be questioned.

Le biopsie prostatiche random nei tumori prostatici allo stadio T1C: Confronto fra la tecnica a 6 sestanti vs quella a 10 sestanti

It is still controversial which prostatic biopsy technique can provide the highest positive rate, complications, prostatic volume and PSA levels being equal. 656 consecutive patients (mean age 62.2 years) were submitted to biopsies using two similar transrectal techniques differing only in the number of biopsies: the “classic” six-sextant and a tensextant technique (adding 4 paraurethral biopsies). Every suspicious or hypoechoic area was also biopsied. Nine per cent (8/89) and 14% (6/42) of the patients subjected to 6-sextant and 10-sextant biopsies respectively, with a PSA level between 4.0-10.0 ng/ml had prostatic cancer. The positive rate increased to 24% (12/49) with sextant plus directed biopsies and to 33% (33/99) with directed biopsies only. Overall, 21% (52/279) of the patients with the above PSA level had a prostatic tumour. The 10-sextant biopsy technique does not seem to be significantly superior to the classic 6-sextant approach.

Computer-assisted comparative analysis of four-sector and six-sector biopsies of the prostate

OBJECTIVES

To assess the potential difference in positive biopsy rates between four-sector and six-sector biopsy methods.

METHODS

This computer-assisted analysis is based on the records of 156 consecutive patients previously diagnosed with T1c cancer on systematic sextant biopsy of the peripheral zone. For each patient the computer randomly deleted one biopsy result from the left and right prostatic lobes. The deletion process was repeated 1000 times. Based on four randomly chosen biopsy cores, we determined the number of undetected cancers initially diagnosed with sextant biopsy.

RESULTS

Based on four-sector biopsy cores of the peripheral zone, between 6 and 30 (3.8% to 19.2% of cases) nonpalpable, isoechoic prostate cancers that were detected with sextant biopsy would have remained undiagnosed.

CONCLUSIONS

Our results suggest that the number of biopsy cores used in the early detection of nonpalpable, isoechoic prostate cancer may substantially affect the rate of positive findings.

Transrectal ultrasound-guided biopsy of the prostate: what you see is not what you get

A prospective trial involving 282 patients, beginning in December 1993, was undertaken to assess the correlation between our sonographic impression of prostatic malignancy and the histological findings of a random six quadrant biopsy in addition to histology of any sonographically evident focal peripheral zone (PZ) abnormality. The sonographic criteria used to suggest malignancy were: (i) presence of hypo-echoic PZ nodule; (ii) inhomogeneity of PZ; and (iii) loss of zonal architecture (ZA). The sonographic appearance was graded as either definitely benign, indeterminate, or definitely malignant. These impressions were then compared with the histology results. Eighty-two patients had histologically proven malignancy. Ultrasound showed the correct extent and site of malignancy in 42 patients. A further 26 patients had the extent of their malignancy either over- or under-estimated or had the malignancy placed in an incorrect site. Fourteen patients with histologically proven carcinoma had sonographically normal PZs. These findings highlight the shortcomings of ultrasound as a diagnostic tool in prostate cancer and show that six quadrant random biopsy of the prostate is far superior to unifocal biopsy of sonographically evident masses in the detection of prostate cancer.