The diagnostic value of colour Doppler flow in the peripheral zone of the prostate, with histological correlation

Comparison of Conventional Color Doppler With Power Doppler Sonograhy to Depict Normal Prostatic Vasculature

Transrectal sonograms of the prostates of 30 healthy men were performed using conventional gray-scale sonography, color Doppler sonography (CDS), and power Doppler sonography (PDS). Representative images were recorded at each of six defined anatomical zones. Images were characterized independently by two reviewers for the degree of capsular and parenchymal vascularity, using semiquantitative scales. Color Doppler sonography showed complete capsular flow in only 3 (10%), sparse capsular flow in 18 (60%), and no capsular flow in 9 (30%) of the 30 subjects. In contrast, PDS showed complete capsular flow in 20 (67%), sparse capsular flow in 10 (33%), and no capsular flow in 0 of the 30 subjects (chi square = 23.85, df = 2, P < 0.0901). These findings suggested that PDS was more sensitive than CDS for demonstrating capsular blood flow. Although both techniques showed parenchymal flow in all subjects, PDS showed more radiating and penetrating parenchymal vessels than CDS. Color Doppler sonography showed short segments of vessels in 20 (67%) of the 30 subjects and complete linear vessels in the remaining 10 subjects (33%). In contrast, PDS showed short segments of vessels in 11 (37%) and complete linear vessels in 19 (63%) of the 30 subjects (chi square = 5.41, df = 1, P = 0.02). Subjectively, both reviewers also found that PDS demonstrated prostatic vasculature better than CDS. Power Doppler sonography proved superior to CDS to demonstrate normal prostatic vasculature.

The adjunctive use of power Doppler imaging in the preoperative assessment of prostate cancer

OBJECTIVE

To determine if the adjunctive use of power Doppler imaging (PDI) could provide prognostic utility in the treatment of prostate cancer, as an accurate prediction of the clinical behaviour of prostate cancer is important to determine appropriate treatment.

PATIENTS AND METHODS

Most centres rely on a digital rectal examination or transrectal ultrasonography (TRUS) to assess the clinical stage of patients. In 2002, we began using a standardized form to evaluate TRUS findings and PDI findings. We compared preoperative clinical findings with those from pathological analysis of 620 radical prostatectomy specimens from 2002 to 2007.

RESULTS

The mean (sd) patient age was 58 (6.6) years with a mean prostate-specific antigen (PSA) level of 7.0 (4.5) ng/mL. Of the 620 specimens 157 (25.3%) had evidence of extracapsular extension on pathological evaluation; 443 (71.5%) men had a hypervascular lesion seen on TRUS, while 177 (28.5%) patients had none. There was no difference in preoperative PSA level, grade or stage of tumour. Furthermore, rates of biochemical recurrence or secondary treatment did not differ based on PDI findings. As a tool to help locate prostate tumours, PDI improved the specificity of TRUS but did not improve the overall accuracy or sensitivity.

CONCLUSION

PDI provides little prognostic utility to assess risk in prostate cancer. However, PDI might improve the specificity of TRUS in identifying prostate tumours and could have a role in image guidance for focal therapy of prostate cancer.

Real-time elastography in the diagnosis of prostate tumor

AIM

To assess the diagnostic gain of transrectal real-time elastography (RTE) compared to transrectal B-mode ultrasonography (US) in the detection of tumors in patients suspected of having prostate cancer.

MATERIALS AND METHODS

Eighty-four patients suspected of having prostate cancer on the basis of clinical and biochemical evaluation underwent transrectal US, RTE and transperineal prostate biopsy.

RESULTS

Biopsy was considered the gold standard. Analysis related to the total number of patients showed a B-mode US sensitivity of 56%, specificity 80%, positive predictive value (PPV) 70% and negative predictive value (NPV) 67%. Analysis related to the total number of biopsy cores showed sensitivity 33%, specificity 92%, PPV 69% and NPV 73%. In the patient-related analysis, RTE sensitivity was 51%, specificity 75%, PPV 64% and NPV 64%, while the core-related analysis showed sensitivity 36%, specificity 93%, PPV 72% and NPV 74%. Comparison of B-mode US and RTE diagnostic accuracy in the detection of tumors located in the peripheral zone of the prostate gland showed a significant difference. Analysis related to the total number of biopsy cores harvested in the peripheral zone of the prostate gland showed a B-mode US sensitivity of 48%, specificity 81%, PPV 75% and NPV 58%, whereas RTE achieved the following values: sensitivity 66%, specificity 78%, PPV 77%, and NPV 67%.

CONCLUSIONS

RTE is a valid addition to B-mode US, and RTE reached a higher accuracy than B-mode US in the evaluation of the peripheral zone of the prostate gland and in the selection of appropriate biopsy sites.

Contrast-enhanced transrectal ultrasound for assessing vascularization of hypoechoic BPH nodules in the transition and peripheral zones: comparison with pathological examination

The purpose of this study was to investigate the vascularization of zonal location of hypoechoic benign prostatic hyperplasia (BPH) nodules and to evaluate the clinical value of contrast-enhanced transrectal ultrasound (CETRUS) for assessing vascularity of hypoechoic BPH nodules. Sixty-two patients with hypoechoic biopsy-proven BPH nodules in transition zone (TZ) (32 patients) or peripheral zone (PZ) (30 patients) of the prostate gland underwent CETRUS examination between January 2006 and September 2006. The enhancement characteristics of hypoechoic BPH nodules were observed and time to enhancement (AT), time to peak intensity (TTP) and peak intensity (PI) were measured with ACQ time-intensity curve analysis software. In addition, microvessel density (MVD) and vascular endothelial growth factor (VEGF) immunoreactivity were determined in the biopsy specimens. Microvessels were identified by immunohistochemical staining of endothelial cells for CD34. Findings were compared between hypoechoic BPH nodules located in PZ and TZ. The most common enhancement characteristic of hypoechoic BPH nodules in PZ was nonenhanced area inside (21/30), while most of hypoechoic BPH nodules in TZ appeared homogeneous enhancement (28/32). The average AT and TTP were significantly longer, the average PI was significantly lower in hypoechoic BPH nodules located in PZ than TZ (p < 0.01). The VEGF expression and MVD were significantly higher in hypoechoic BPH nodules located in TZ than PZ (p < 0.01). PI was found to be an important parameter strongly correlated with degree of vascularity of hypoechoic BPH nodules. Hypoechoic BPH nodules located in PZ and TZ showed significant difference in vascularization, which indirectly verified our finding that BPH nodule could occur in the peripheral zone. CETRUS could afford information on the vascularity of hypoechoic BPH nodules in a noninvasive manner and this could be used to improve selection of nodules for biopsy.

Enhancement characteristics of benign and malignant focal peripheral nodules in the peripheral zone of the prostate gland studied using contrast-enhanced transrectal ultrasound

AIM

To assess the value of contrast-enhanced grey-scale transrectal ultrasound (CETRUS) in predicting the nature of peripheral zone hypoechoic lesions of the prostate.

MATERIALS AND METHODS

Ninety-one patients with peripheral zone hypoechoic lesions on ultrasound were evaluated with CETRUS followed by lesion-specific and sextant transrectal ultrasound-guided biopsies. The enhancement patterns of the lesions were observed and graded subjectively using adjacent peripheral zone tissue as the reference. Time to enhancement (AT), time to peak intensity (TTP) and peak intensity (PI) were quantified within each nodule. Ultrasound findings were correlated with biopsy findings.

RESULTS

Transrectal ultrasound-guided biopsy of the hypoechoic lesions revealed prostate cancer in 44 patients and benign prostatic diseases in 47. The intensity of enhancement within the lesions were graded as no enhancement, increased, equal, or decreased compared with adjacent peripheral zone tissue in two, 30, five and seven in the prostate cancer group and 14, 15, four and 14 in the benign group, respectively. The difference was statistically significant (p<0.05). The peak enhancement intensity was found to be the most optimal discriminatory parameter (area under curve AUC 0.70; 95% CI: 0.58, 0.82).

CONCLUSION

Malignant hypoechoic nodules in the peripheral zone of the prostate are more likely to enhance early and more intensely on CETRUS. A non-enhanced hypoechoic peripheral zone lesion was more likely to be benign.

Peripheral zone hypoechoic lesions of the prostate: evaluation with contrast-enhanced gray scale transrectal ultrasonography

OBJECTIVE

The purpose of this study was to evaluate the efficacy of contrast-enhanced gray scale transrectal ultrasonography (TRUS) for detection of prostate cancer in peripheral zone hypoechoic lesions of the prostate.

METHODS

The study involved 66 patients with peripheral zone hypoechoic lesions detected by TRUS. The lesions were evaluated with contrast-enhanced TRUS to differentiate prostate cancer from benign lesions, and the results were compared with color Doppler ultrasonographic findings.

RESULTS

Transrectal ultrasonographically guided biopsy of the hypoechoic lesions revealed prostate cancer in 30 patients and benign prostatic diseases in 36. Flow signals within the lesions were classified as no, increased, equal, and decreased flow compared with surrounding peripheral zone tissue as follows: 1, 16, 12, and 1, respectively, in the prostate cancer group and 10, 12, 10, and 4 in the benign disease group. If we considered an increased flow signal within a peripheral hypoechoic lesion as a sign of prostate cancer, color Doppler ultrasonography had low sensitivity and specificity (55.2% and 53.8%, respectively). The enhancement intensity within the lesions was classified as no, increased, equal, and decreased enhancement compared with surrounding peripheral zone tissue as follows: 2, 20, 3, and 5 in the prostate cancer group and 14, 8, 4, and 10 in the benign disease group. The difference was statistically significant (P<.05). Thus, the peak enhancement intensity would be the optimal parameter for discriminatory performance (area under the receiver operating characteristic curve, 0.74; 95% confidence interval, 0.60-0.88).

CONCLUSIONS

Contrast-enhanced TRUS could reveal the presence of vasculature within peripheral zone hypoechoic lesions more objectively than color Doppler ultrasonography and could be promising in guidance of prostate biopsy.

Does benign prostatic hyperplasia originate from the peripheral zone of the prostate? A preliminary study

OBJECTIVE

To compare the histological characteristics, cell proliferation, apoptosis and biological features in benign prostatic hyperplasia (BPH) in the peripheral (PZ) and transition zone (TZ) of the prostate.

PATIENTS AND METHODS

Tissue from BPH in TZ and PZ was obtained from 68 patients undergoing transrectal ultrasonography-guided biopsy and used for both morphometric analysis and immunohistochemical studies. The epithelial, stromal and luminal composition of the tissue was determined using a computer-assisted method for quantitative morphometric analysis. Apoptosis was detected as the apoptotic index (AI) using the TdT dUTP nick-end labelling assay. Cell proliferation was determined as the proliferation index (PI) using Ki-67 immunostaining. The expression of epidermal growth factor receptor (EGFR), transforming growth factor beta1 (TGFbeta1), androgen receptor (AR) and bcl-2 were assessed immunohistochemically.

RESULTS

There was no difference in the stroma/epithelium ratio between PZ and TZ hyperplastic nodules (P > 0.05). The mean AI in epithelium was almost identical to the corresponding PI. In stroma, no apoptotic cells were detectable. There was a significantly higher PI and AI in the glandular epithelial cells in PZ hyperplastic than in TZ hyperplastic nodules, but no difference in PI of the stromal cells between PZ and TZ hyperplastic nodules. There was significantly higher expression of TGFbeta1 and lower expression of EGFR and bcl-2 in PZ than TZ hyperplastic nodules (P < 0.05). There was no difference in AR expression between PZ and TZ hyperplastic nodules (P > 0.05).

CONCLUSIONS

These results indicate that some hyperplastic nodules in PZ might originate from the PZ, and the formation of these nodules might be modulated in a different way from that in the TZ.

Advances in transrectal ultrasound imaging of the prostate

Grayscale imaging of the prostate is the basic method for diagnostic evaluation and biopsy guidance. Doppler imaging may improve sensitivity for detection of prostate cancer. Microbubble contrast agents represent a major advance to more selectively demonstrate neovascular flow within the prostate. Recently, real-time elastography has been introduced to improve detection of cancer based upon changes in tissue stiffness. As diagnostic methods improve, the ultimate hope is to eliminate biopsy in patients without cancer. New ultrasound-based treatment systems, such as high-intensity focused ultrasound ablative therapy for prostate cancer, may someday allow diagnosis and treatment of prostate cancer to be completed in one sitting.

Inflammatory disorders of the prostate and the distal genital tract

Inflammatory disease of the prostate and distal genital tract is emerging as a major health problem because it is estimated that up to 15% of adult men may be affected at some point in their lives. Clinically, the diagnosis of "prostatitis" refers to multiple disorders that cause pelvic pain and discomfort, ranging from acute bacterial infection to complex conditions that may not necessarily be caused by prostatic inflammation. Because the traditional etiology-based classification system did not always correlate with symptoms and therapeutic efficacy, a new classification of prostatitis has been suggested by the National Institutes of Health. New imaging techniques such as high-resolution transrectal ultrasonography (TRUS) and MR imaging provide exquisite anatomic detail and often play a crucial role in the evaluation of these patients.

Transrectal sonography in prostate evaluation

Prostate cancer is the most prevalent newly diagnosed noncutaneous malignancy in men. With the continued use of prostate-specific antigen screening, there has been a dramatic rise in the number of prostate biopsied performed. Transrectal ultrasonography (TRUS) is an essential tool used for detecting prostate pathology and performing prostate biopsies. This article review the indications and principles of TRUS of the prostate, the technique of TRUS, and controversies pertaining to prostate core biopsy.

Newer Modalities of Ultrasound Imaging and Treatment of the Prostate

Gray-scale ultrasound is widely used for assessing BPH and for obtaining prostate biopsies. However, it has limited value for evaluating cancer in the prostate. To improve ultrasound as an imaging modality of the prostate, many new technologies, such as color and power Doppler, 3-dimensional ultrasound of the prostate, and contrast-enhanced ultrasound have been developed. In addition, treatment modalities using ultrasound for the treatment of BPH have been developed. This review presents the recent developments in ultrasound of the prostate.

Current status of transrectal ultrasound-guided prostate biopsy in the diagnosis of prostate cancer

In contemporary practice, most prostate cancers are either invisible on ultrasound or indistinguishable from concurrent benign prostatic hyperplasia. Diagnosis therefore rests on prostate biopsy. Biopsies are not simply directed at ultrasonically visible lesions, as these would miss many cancers; rather the whole gland is sampled. The sampling itself is systematic, using patterns based on prostate zonal anatomy and the geographical distribution and frequency of cancer. This review explains the evolution of the prostate biopsy technique, from the classical sextant biopsy method to the more recent extended biopsy protocols (8, 10, 12, >12 and saturation biopsy protocols). Extended protocols are increasingly being used to improve diagnostic accuracy, especially in those patients who require repeat biopsy. This trend has been facilitated by the ongoing improvement in safety and acceptability of the procedure, particularly with the use of antibiotic prophylaxis and local anaesthesia. The technical details of these extended protocols are discussed, as are the current data regarding procedure-related morbidity and how this may be minimized.

A comparison of the diagnostic performance of systematic versus ultrasound-guided biopsies of prostate cancer

Transrectal ultrasound (TRUS) is an important tool for urologists and radiologists in the detection of prostate cancer. Various TRUS-guided biopsy techniques are applied in clinical practice. Frequently, only the detection rates achieved with these methods are compared. Other diagnostic performance parameters, particularly the specificity and negative predictive value, are seldom compared. After extensive assessment of the available literature, this review describes the methods of TRUS-guided biopsy for prostate cancer detection. A distinction was made between systematic biopsies and biopsies that target a perceived (hypoechoic or Doppler-enhancing) lesion on imaging. Subsequently, the diagnostic performance (sensitivity, specificity, positive and negative predictive values, accuracies) was compared between these techniques. Imaging-guided biopsy showed better diagnostic performance than systematic biopsy with higher sensitivity. The combinations of sensitivity and specificity were highest for colour Doppler and contrast-enhanced targeted biopsy. Studies targeting hypoechoic lesions had relatively high sensitivity, but specificity was low. Presently however, with widespread prostate-specific antigen screening, fewer prostate cancers are hypoechoic, and the value of targeting hypoechoic lesions has diminished. Performing colour or contrast-enhanced Doppler biopsy or adding these techniques to systematic biopsies improves diagnostic performance, particularly by increasing sensitivity.

Cancer of the prostate

Prostate carcinoma, with about 190,000 new cases occurring each year (15% of all cancers in men), is the most frequent cancer among men in northern and western Europe. Causes of the disease are essentially unknown, although hormonal factors are involved, and diet may exert an indirect influence; some genes, potentially involved in hereditary prostate cancer (HPC) have been identified. A suspect of prostate cancer may derive from elevated serum prostate-specific antigen (PSA) values and/or a suspicious digital rectal examination (DRE) finding. For a definitive diagnosis, however, a positive prostate biopsy is requested. Treatment strategy is defined according to initial PSA stage, and grade of the disease and age and general conditions of the patient. In localized disease, watchful waiting is indicated as primary option in patients with well or moderately differentiated tumours and a life expectancy <10 years, while radical prostatectomy and radiotherapy (with or without hormone-therapy) could be appropriate choices in the remaining cases. Hormone-therapy is the treatment of choice, combined with radiotherapy, for locally advanced or bulky disease and is effective, but not curative, in 80-85% of the cases of advanced disease. Patients who develop a hormone-refractory prostate cancer disease (HRPC) have to be evaluated for chemotherapy because of the recent demonstration of improved overall survival (2-2.5 months) and quality of life with docetaxel in more than 1,600 cases.

Correlation between hypoechoic nodules on ultrasonography and benign hyperplasia in the prostatic outer gland

OBJECTIVE

The purpose of this investigation was to study the correlation between hypoechoic nodules detected on ultrasonography and benign hyperplasia in the prostatic outer gland (POG) diagnosed by transrectal ultrasonography (TRUS)-guided biopsies.

METHODS

The TRUS-guided biopsies were performed on 472 patients suspected of having prostate cancer. Specimens obtained by biopsies were independently assessed by pathologists at 3 hospitals.

RESULTS

The histologic results of 310 patients (65.68%) were benign. Focal hypoechoic nodules located in the POG were found in 240 patients (50.8%) on TRUS scans. Among them, in 22 patients (9.17% of the 240 patients with hypoechoic nodules), benign hyperplasia was found in focal hypoechoic nodules located in the POG. Focal nodules were seen as well circumscribed with an ovoid shape and smooth surface in 18 patients.

CONCLUSIONS

Benign hyperplasia may sometimes originate in the POG and may appear as a hypoechoic nodule, similar to the appearance of prostate cancer.

Color and power Doppler sonography in the diagnosis of prostate cancer: comparison between vascular density and total vascularity

OBJECTIVE

Advances in color flow Doppler (CFD) and power Doppler imaging (PDI) have potential for prostate cancer diagnosis. Previous reports based on qualitative assessment suggest that hypervascularity increases likelihood of prostate cancer. Our objective was to compare 2 methods of vascularity assessment using PDI: total vascularity (TV) and vascular density (VD). The goal was to determine whether quantitative Doppler vascularity correlates with the likelihood of prostate cancer. Quantitative measurements were compared with subjective visual analysis of images.

METHODS

Ninety patients before biopsy had gray scale sonography, CFD, and PDI. Histologic analysis showed adenocarcinoma, prostate intraepithelial neoplasia, benign prostatic hypertrophy/prostatitis, and benign findings. The CFD and PDI images were analyzed for vascularity by (1) integrating the number of blood vessels over an imaged area (TV) and (2) integrating the number of vessels over a unit area of tissue (VD). Images were also assessed visually. VD, TV, and visual assessment were compared with one another and histologic findings.

RESULTS

Mean volume was not different. In each pathologic group, vascularity extent measured by TV and VD ranged from low to high. Disease groups did not exhibit a substantial difference in vascularity by either quantitative or qualitative analyses. Regionally, central gland TV was not significantly more vascular than peripheral gland TV except in benign prostatic hypertrophy. However, peripheral gland VD was 2.5 times greater than central gland VD. Seventy-one percent of the 31 focal hypoechoic lesions were hypervascular. Only 23% were carcinoma.

CONCLUSIONS

Pathologic categories were not separable by apparent vascular measurement. All pathologic categories showed low, moderate, or high vascularity; thus vascular areas by themselves did not distinguish cancer types, nor did focal hypervascular hypoechoic areas increase the likelihood of cancer. These imaging techniques provided no further resolution of tumor discrimination over multiple biopsies of the prostate.

Does the adjunct of ecographic contrast medium Levovist improve the detection rate of prostate cancer?

OBJECTIVES

To evaluate whether the adjunct of an ultrasound contrast medium improves the detection rate of prostate cancer.

METHOD

In 34 patients, scheduled to undergo a trans-perineal extended prostate biopsy, we carried out a color-Doppler ultrasound (CDU) of the prostate before and after i.v. injection of Levovist, an ultrasound contrast medium. Further bioptic samples were taken in the areas where a marked increase in vascularization was noticed.

RESULTS

The overall diagnostic sensitivity, specificity and efficiency were respectively 72.7, 56.2 and 62.9% for transrectal ultrasound (TRUS); 80, 56.2 and 65.3% for CDU and 88.8, 54.5 and 68% for CDU after Levovist injection; 66.5, 72.6 and 65.1% for digito-rectal examination (DRE); 100, 51.4 and 65.4% for total PSA; and 100, 88.8 and 94.3% for PSA free/total. In the 16 patients with prostate carcinoma, the sensitivity of CDU after Levovist was 92.3, 66% for both DRE and TRUS, and 80% for DRE plus TRUS.

CONCLUSIONS

Considering the cost and the results obtained (high sensitivity and low specificity), a routine use of Levovist does not seem indicated in patients undergoing prostatic biopsy. An exception may be represented by patients with both negative DRE and TRUS.

Imaging clinically localized prostate cancer

At this time there is no highly sensitive and specific widespread radiographic test for local staging of prostate cancer. Future developments will likely require a combination of imaging modalities with utilization guided by risk-stratification models (Table 4). Staging data for all imaging tests discussed in this article are summarized in Tables 5 and 6. Clinically, conventional gray-scale TRUS remains the most frequently used tool because of its utility in guiding prostatic biopsies. Modifications of TRUS--including power and color Doppler, 3D imaging, and new ultrasound contrast agents and elastography--show promise in increasing the accuracy of ultrasound. Endorectal MRI may have some value for staging selected patients. The addition of prostatic MRS, which images the differential activity of metabolites, may increase the specificity of MRI. Newer techniques with finer voxel resolution may prove to be clinically useful. A large well-designed study evaluating the utility of MRI/MRS is currently being planned. Cross-sectional imaging of the pelvis with either MRI or CT should be used selectively as should radionuclide bone scans. Similarly, ProstaScint scans should be ordered selectively, either before or after primary therapy, rather than routinely in all patients.

Correlation between Doppler vascular density and PSA response to radiation therapy in patients with localized prostate carcinoma

RATIONALE AND OBJECTIVES

The authors performed this study to ascertain whether there is a correlation between pretreatment Doppler vascular density (DVD) of the prostate and prostate-specific antigen (PSA) response following radiation therapy in prostate cancer patients.

MATERIALS AND METHODS

Prior to radiation therapy, 14 patients with biopsy-proven carcinoma (of Gleason grades 2-7) were imaged with transrectal ultrasound in gray-scale, color Doppler, and power Doppler modes. The Doppler images were analyzed for mean DVD with the aid of a computer program. PSA levels were measured before therapy and every 3 months after therapy. The PSA measurements were fitted to an exponential to determine PSA halving time (T1/2). Correlations were made between T1/2 and the following pretherapy measurements: mean DVD, PSA level, prostate volume, and Gleason grade.

RESULTS

Median follow-up time was 392 days. A linear correlation with regression coefficient (R) of 0.75-0.80 was observed between mean DVD and T1/2 for color Doppler and power Doppler imaging. In both imaging modes, each percentage increase in mean DVD led to an increase in T1/2 by 25 days. Pretherapy prostate volume, PSA level, and Gleason score did not correlate with T1/2.

CONCLUSION

The pretreatment mean DVD correlates inversely with the rate of posttherapy decline in PSA in patients with prostate cancer. That is, pretreatment vascularity prognosticates postirradiation PSA response. The mechanism underlying this correlative relationship is not known.

[Transrectal ultrasound of the prostate. Current status and prospects]

In recent years the role of ultrasound in the diagnosis of prostate carcinoma has increased in importance. In view of the increasing incidence of prostate cancer, which is the most frequent malignant neoplasm in men, TRUS (transrectal ultrasound) is an important imaging method in the diagnosis of various prostate diseases. This paper provides a basic overview of physical and technical bases of TRUS investigation of the prostate. It concerns technical developments and modern techniques designed to improve its value in diagnosis. Impressive innovations in ultrasound equipment, particularly in the area of colour-coded Doppler sonography in association with microbubble-enhanced colour Doppler ultrasound, have given rise to justifiable hope of improvements in the early diagnosis of prostate cancer.

Ultrasound for prostate imaging and biopsy

Transrectal ultrasound guided systemic sextant needle biopsy of the prostate has been the procedure of choice for the diagnosis of prostate cancer. Several shortcomings of this procedure have been recognized and there is concern that it may represent an inadequate sampling of the prostate. Refinements include modifications of biopsy location and an increase in the number of cores obtained. Enhanced ultrasound techniques may improve the accuracy of prostate biopsy. In addition, research continues to develop prognostic factors derived from the core biopsy that may enhance the prediction of tumor biology. This paper provides a basic review of transrectal ultrasound diagnosis of prostate cancer with emphasis on advances in this area.

Color Doppler imaging of the prostate: important adjunct to endorectal ultrasound of the prostate in the diagnosis of prostate cancer

The purpose of this article is to evaluate color Doppler imaging (CDI) as an adjunctive tool to gray-scale ultrasound (US) in the diagnosis of prostate cancer and to correlate CDI-positive lesions to cancer grade. We retrospectively analyzed 619 consecutive patients who underwent prostate US, CDI, and biopsy because of abnormal digital rectal examination results or prostate-specific antigen levels. All had directed (into a specific lesion) biopsies or directed biopsies along with systematic four-quadrant or sextant biopsies, or systematic biopsy alone. Color Doppler imaging was compared with gray-scale findings and histologic results. There were 222 (35.9%) biopsy-proven cancers (n = 197) or prostatic intraepithelial neoplasia (n = 25). Of these, 106 (47.7%) had color-flow abnormalities. Of these 106 patients, 26 (24.5%), or 11.7% of all cancer patients, had relatively normal gray-scale US findings but had focal CDI abnormalities as the method of identification. Overall, 76.9% of these were moderate to high Gleason grades and were considered clinically significant lesions. Color Doppler imaging can identify a large number (11.7%) of clinically significant prostate cancers that are poorly seen by gray-scale US. Positive lesions on CDI are of clinical importance because 76.9% are histologically, moderately, or poorly differentiated. We recommend that CDI be used in all diagnostic and biopsy-guided US examinations of the prostate.

Analysis of three-dimensional ultrasound Doppler for the detection of prostate cancer

OBJECTIVES

To investigate the relative effectiveness of Doppler ultrasound quantitative measures in discriminating prostate cancer from normal prostate tissue. The true locations of prostate cancer within these prostates were determined by histologic examination after radical prostatectomy.

METHODS

Three-dimensional Doppler ultrasound data were acquired from 39 men before radical prostatectomy. The removed prostates were sectioned and all cancerous regions in each prostate were identified on whole-mount hematoxylin-eosin-stained slides. The ultrasound and histologic data were then spatially registered. Biopsy results were simulated on a grid of potential sites within each prostate. Along each simulated biopsy site, the amount of cancer was computed from the hematoxylin-eosin-identified cancerous regions and the peak speed-weighted pixel density (SWD) was compared.

RESULTS

By selecting the biopsy sites with higher associated SWDs within each sextant, the probability of having at least one positive biopsy within a prostate increased from 75% if the SWD was ignored to 85% if only the top 15% of potential biopsy sites in each sextant were selected. This trend was seen within each sextant individually as well.

CONCLUSIONS

Doppler ultrasound provides discriminatory information for prostate cancer using the SWD. Translating this into a practical strategy that might improve the yield of prostate biopsy remains under development. The results of our study indicate that biopsying regions of high Doppler color could potentially increase the cancer yield to a small degree and improve the accuracy of the biopsy results. These results also objectively verify previous visual studies suggesting a modest improvement with the use of color Doppler.

Characteristics of normal prostate vascular anatomy as displayed by power Doppler

BACKGROUND

To define the vascular anatomy of the normal prostate as depicted by power Doppler and to provide baseline data for evaluation of this modality in the diagnosis and management of prostatic disease.

METHODS

The vascular anatomy of 40 subjects was studied. Power Doppler images were correlated with corresponding gray-scale images. Doppler spectral waveform measurements were obtained for the vessels identified.

RESULTS

Separate branches of the capsular vessels were visualized clearly, distributed radially in the peripheral and central zones and converging toward the center of the gland. Urethral vessels were visualized in the transition zone coursing from bladder neck to verumontanum. The neurovascular bundles were identified posterolaterally along the length of the gland. No significant difference between the resistive indexes of the urethral and capsular vessels was identified (P = 0.595), although there was a significant difference between the resistive index of the neurovascular bundles and that the prostatic vessels (P < 0.001).

CONCLUSIONS

The vascular anatomy of the normal prostate as displayed by power Doppler demonstrates a reproducible and symmetric flow pattern. Power Doppler is highly sensitive in depicting blood flow, the number, course, and continuity of vessels more readily than other imaging modalities, such as color Doppler. These data should allow comparison of the vascular anatomy of the normal prostate with that of the prostate with diseases such as prostate cancer and benign prostatic hyperplasia.

New developments in ultrasonography for the detection of prostate cancer

The introduction of contrast agents has changed the diagnostic role of ultrasonography dramatically. Advanced ultrasound techniques, although currently largely unexplored, especially for prostate applications, were introduced to improve, for example, differential diagnosis. Also, new technologies became available using the interaction of the angioemboli with the transmitted ultrasound waves, and sensitive methods to detect microbubbles were developed. As the traveling of microbubbles through the vascular system is a dynamic process, new information becomes available: when the concentration of the contrast agent can be determined as a function of time, a measure for the actual blood flow can be obtained that provides quantitative information. Initially developed to enhance the ultrasound examinations in cardiac applications, contrast agents can currently be found in radiologic applications as well. The first reports of enhanced Doppler examinations of prostatic blood flow have been published, and the results indicate that contrast agents are a promising addition to the conventional ultrasound examination. In this paper, we present a short overview of the status of transrectal ultrasound imaging in prostate cancer, background information on contrast agents and imaging modalities, and early results of enhanced Doppler studies of the prostate to identify cancer. The early results suggest the feasibility of using angioemboli to enhance ultrasound imaging of prostate diseases, and although many issues remain to be solved, angioemboli in combination with a dedicated imaging modality have the potential to improve the diagnostic application of ultrasound in evaluating the prostate for disease.

Prostate vascular flow: the effect of ejaculation as revealed on transrectal power Doppler sonography

OBJECTIVE

The objective of our study was to determine the effect of ejaculation on prostate vascular flow.

SUBJECTS AND METHODS

Using power Doppler technology, we performed four transrectal sonographic examinations before and immediately, 6 hr, and 24 hr after ejaculation in 10 healthy volunteers. Images were assessed by three independent observers.

RESULTS

Ninety-seven percent of the images ranked as having the least flow were from the baseline examination. There was a significant difference between the rankings when categorized into the four time sets (mean score for the baseline group was 1.1, whereas for the immediate, 6-, and 24-hr postejaculation groups it was 2.5, 2.9, and 2.4, respectively (p<0.0001). The only statistically significant difference was between the baseline and the three remaining groups. Interobserver agreement was high, with the chance-corrected measure of agreement of 0.78.

CONCLUSION

Transrectal sonography revealed that prostate vascular flow increases dramatically after ejaculation and remains elevated for at least 24 hr. This observation should be considered when power Doppler sonography is used to assess for potential hyperemia in patients suspected of having prostate abnormalities.

Contrast-enhanced three-dimensional power Doppler angiography of the human prostate: correlation with biopsy outcome

OBJECTIVES

To determine the feasibility of contrast-enhanced three-dimensional (3D) imaging of the prostatic vasculature using power Doppler imaging and to analyze whether semiquantitative judgments of 3D images with respect to symmetry and distribution of vascular structures correlated with biopsy outcome.

METHODS

3D power Doppler images were obtained before and after intravenous administration of 2.5 g Levovist. Subsequently, random and/or directed transrectal ultrasound (TRUS)-guided biopsies were performed. Vascular images were analyzed by two experts. Prostate vasculature was judged with respect to symmetry and vessel distribution using a (scale) grading system.

RESULTS

Eighteen patients with a suspicion of prostate cancer either because of an elevated prostate-specific antigen (greater than 4.0 ng/mL; Tandem-R-assay) or an abnormal digital rectal examination were included in the study. Prostate cancer was detected in 13 patients. Vascular anatomy was judged abnormal in unenhanced images in 6 cases, of which 5 proved malignant. Enhanced images were considered suspicious for malignancy in 12 cases, including 1 benign and 11 malignant biopsy results. Sensitivity of enhanced images was 85% (specificity 80%) compared with 38% for unenhanced images (specificity 80%) and 77% for conventional gray-scale TRUS (specificity 60%). Of 6 patients who showed no B-mode abnormalities, vascular patterns were judged abnormal in 4 cases, of which 3 were malignant.

CONCLUSIONS

Contrast-enhanced 3D power Doppler angiography is feasible in patients with suspicion of prostate cancer who are scheduled for prostate biopsies. The sensitivity of power Doppler 3D imaging for the detection of prostate malignancy increased from 38% (5 of 13) to 85% (11 of 13) after administration of intravascular microbubble contrast (Levovist), and specificity was found to be 80% (4 of 5) for both imaging modalities. Thus, the use of Levovist when combined with the power Doppler display mode and 3D image reconstruction offers a promising new research area that might prove useful in prostate cancer detection in the future.

Patient assessment in chronic prostatitis

Assessment of men suffering from proven chronic prostatitis involves a cascade of diagnostic steps, including evaluation of symptoms and clinical features, objectivation of the inflammatory response in expressed prostatic secretions, standardized localization techniques for common bacteria and a search for fastidious, uncommon pathogens.

The role of color Doppler and staging biopsies in prostate cancer detection

OBJECTIVES

To review the current published data on the role of color Doppler sonography and sonographically-guided staging biopsies in the detection and staging of prostate cancer. This article also discusses the role of color Doppler sonography in defining the ideal patients for neoadjuvant chemotherapy.

METHODS

Peer-reviewed reports in the radiologic, urologic, and medical literature were reviewed. Data from our own institution served as illustrative material.

RESULTS

Color Doppler sonography using state of the art ultrasound equipment produced from the mid 1990s onward can define areas of hypervascularity in the prostate. When located in the peripheral zone and associated with definable lesions, these areas likely represent carcinoma. More importantly, when isoechoic areas contain hypervascular foci with chaotic flow, cancer is also likely. In 93% of sites that contain normal vascularity, prostate cancer was not detected by biopsy. Staging biopsies are not frequently performed in current clinical practice. A positive seminal vesicle biopsy is associated with capsular penetration in 100% and positive lymph nodes in 50% of patients with prostate cancer.

CONCLUSIONS

Color Doppler sonography and staging biopsies may have a more significant role as newer alternative therapies for prostate cancer become popular. These two techniques show promise for increasing the accuracy of pretreatment staging over current algorithms, which are less than adequate.