Microvessel density: correlation between contrast ultrasonography and histology of prostate cancer

OBJECTIVE

Increased microvessel density (MVD) of prostate cancer seems to be associated with poor prognosis and higher stage. Assessment of MVD using noninvasive methods could be of use in the work-up of patients with prostate cancer. The aim of the present study was to correlate three-dimensional contrast-enhanced power Doppler ultrasound (3D-CE-PDU) findings with MVD characteristics of radical prostatectomy specimens.

METHODS

Seven patients with biopsy-proven prostate cancer had 3D-CE-PDU investigations 2-3 weeks after prostate biopsies were taken and prior to radical prostatectomy. The investigations were performed using Levovist contrast agent (Schering AG, Berlin, Germany) in combination with a Voluson 530D ultrasound scanner (Kretz AG, Zipf, Austria). The 7 patients were selected because of lateralization of the contrast enhancement. Histology slides were made of the side with 'contrast enhancement' and of the contralateral 'unenhanced' side and stained according to the catalyzed reporter deposition (CARD) amplification procedure, and MVD parameters were obtained.

RESULTS

In all patients the MVD count of the 'enhanced' side was higher than the MVD count of the 'unenhanced' side, averaging 1.93 times higher. On histology all enhanced lesions proved to contain prostate cancer tissue (average maximum diameter 25 mm (range 17-31)). Two patients had a small bilateral tumor lesion (4 and 5 mm respectively) and in total 5 patients had even smaller satellite lesions (1-2 mm). The smaller lesions were not identified using 3D-CE-PDU.

CONCLUSIONS

The present study shows that 3D power Doppler contrast ultrasonography is a minimally invasive imaging modality, which has the potential to visualize lesions with increased MVD. This property of 3D-CE-PDU could be used in the detection of prostate cancer.

Transrectal ultrasound in the diagnosis of prostate cancer: state of the art and perspectives

OBJECTIVES

Transrectal ultrasound (TRUS) is an important tool in diagnosing prostate cancer. However, specificity and sensitivity of conventional grey-scale TRUS for the detection of prostate cancer are disappointingly low. New ultrasound modalities are designed to overcome the disappointing results and improve the use of ultrasound in the diagnosis of prostate cancer. This work is a review of the recent literature, combined with own experiences.

METHODS

The papers were collected using a Medline search, combined with some papers by author selection. The terms used for the Medline search included among other things: transrectal ultrasound, prostate, prostate cancer, prostate biopsies, colour Doppler ultrasound, power Doppler ultrasound, contrast ultrasound. The authors used their own experiences for illustrations of various techniques.

RESULTS AND CONCLUSIONS

Although several modalities show a significant improvement in sensitivity and specificity for the detection of prostate cancer, none of the TRUS modalities discussed can replace prostate biopsies as a definitive diagnostic. Several techniques, especially contrast ultrasound, show definitive promise. However, two valid conclusions can be made from the data presented. First: with today's technology, none of the TRUS modalities discussed can replace systemic biopsies in the early detection of prostate cancer. Second: none of the discussed TRUS modalities has found a definitive place in routine clinical practice.

Three-dimensional grayscale ultrasound: evaluation of prostate cancer compared with benign prostatic hyperplasia

OBJECTIVES

To compare the accuracy of the detection, localization, and staging of prostate cancer using transrectal three-dimensional (3D) grayscale ultrasonography (3D-US) with conventional transrectal two-dimensional grayscale ultrasonography (2D-US).

METHODS

Fifty patients with clinical localized prostate cancer scheduled to undergo radical retropubic prostatectomy and 50 patients with clinical benign prostatic hyperplasia underwent transrectal ultrasound investigations (2D and 3D). The prostate images were retrospectively analyzed by two ultrasound experts unaware of the clinical findings. The images of the prostate cancer group were correlated with the whole-mount histologic specimens of the prostate.

RESULTS

All percentages are given for experts 1 and 2. The sensitivity, specificity, and accuracy for the detection of prostate cancer without considering the definitive localization of the tumor for 2D-US was 72% and 76%, 50% and 54%, and 63% and 64%, respectively; for 3D-US, the rates were 82% and 88%, 40% and 42%, and 61% and 65%. The sensitivity, specificity, and accuracy of the combination of 2D-US with 3D-US was 88% and 90%, 36% and 38%, and 62% and 64%, respectively. The sensitivity, specificity, and accuracy for the exact localization of the prostate tumor for 2D-US was 44% and 46%, 50% and 54%, and 47% and 50%, respectively; for 3D-US, they were 52% and 62%, 40% and 42%, and 46% and 52%. The staging of prostate cancer using 3D-US was correct in 49% (expert 1) and in 57% (expert 2) of patients. No difference was observed between 2D-US and 3D-US for accurate staging. Both experts judged the interpretation of 3D-US images as superior to that of 2D-US images.

CONCLUSIONS

Although 3D-US had statistically significant increased sensitivity in the detection of lesions and decreased specificity compared with 2D-US, 3D-US did not result in significant clinical improvement in the detection and staging of prostate cancer.

Reproducibility of contrast-enhanced transrectal ultrasound of the prostate

Transrectal three-dimensional (3-D) contrast-enhanced power Doppler ultrasound (US) is a novel technique for studying possible prostate malignancy. Before studies can be performed to investigate the clinical validity of the technique, reproducibility of the contrast US studies must be proven. Reproducibility of contrast US was studied in 10 patients with biopsy-proven prostate cancer. The studies performed included static investigations and dynamic investigations of the prostate vasculature. All studies were double performed. The assessment of reproducibility was done objectively using a computer program and, subjectively, by visual assessment. The results indicate high reproducibility of static contrast investigations, for both the objective and subjective assessment. The subjective assessment of the dynamic studies was also highly reproducible. The objective assessment of the dynamic contrast studies, however, was less reproducible, mainly due to motion artefact. We concluded that, especially static 3-D contrast-enhanced, power Doppler investigations of the prostate are highly reproducible.

Intra-prostatic vasculature studies: can they predict the outcome of transurethral microwave thermotherapy for the management of bladder outflow obstruction?

BACKGROUND

Blood perfusion regulates intraprostatic temperatures during transurethral microwave thermotherapy (TUMT). We evaluated baseline intraprostatic vasculature, as a predictor of efficacy of TUMT.

METHODS

Twenty-two patients, with lower urinary tract symptoms (LUTS) suggestive of bladder outflow obstruction, were treated with TUMT (Prostatron). At baseline, three-dimensional contrast-enhanced power-flow-Doppler prostate ultrasonography (3D-CE-PFD) was performed. Assuming that the percentage of perfused area (PPA) is a realistic measure of blood flow, it was used to quantify intraprostatic vasculature.

RESULTS

The median (range) age, prostate size, and energy delivered were 66 years (48-80), 47 cm(3) (30-121), 110 kJ (29-136), respectively. The response was 77% (5 failures). The median (range) PPA was 2.76% (0.7-11.3). No difference in PPA among good and poor responders was detected nor was any correlation between PPA and baseline parameters.

CONCLUSIONS

The baseline intraprostatic vascularization, documented by CE-PFD studies, has no predictive value for the efficacy of TUMT. It seems that "static" baseline blood flow does not reflect the "dynamic" thermoregulatory role of blood flow during treatment.

Recurrence of germ cell tumor after orchiectomy

OBJECTIVES

To assess the characteristics of patients with recurrent disease by a retrospective analysis.

METHODS

Between 1982 and 1998, 488 patients were treated in Nijmegen for testicular cancer. All patients underwent orchiectomy and adjuvant treatment when indicated. Patients were routinely followed up.

RESULTS

In 36 patients (7.4%), disease recurrence was found during follow-up; 12 had contralateral disease and 24 systemic recurrence. Contralateral testicular cancer occurred a median of 63.8 months (range 43.2 to 165.2) after orchiectomy and systemic recurrence at a median of 6.1 months (range 1.5 to 94.4). Contralateral testicular cancer was more frequent in patients with pure seminoma (odds ratio 4.3, 95% confidence interval 1.4 to 13.1); 8 of 9 patients with contralateral cancer received adjuvant radiotherapy. The best predictor of systemic recurrence after nonseminoma germ cell tumor was the presence of teratoma and embryonal cell components in the primary tumor. In the entire population, 19 patients (3.9%) died of the disease. None of the patients with contralateral testicular recurrence or systemic recurrence after Stage I seminoma died of the disease. One of 10 patients died of recurrent Stage I nonseminoma germ cell tumor. The chance of dying of recurrence after metastatic nonseminoma germ cell tumor was 36%.

CONCLUSIONS

Recurrence after an initially complete response is rare in testicular cancer. Contralateral testicular cancer is associated with the presence of seminoma components in the primary tumor and occurs almost 10 times later than systemic recurrence. The prognosis after contralateral testicular cancer and after recurrence in Stage I seminoma is good.

Three-dimensional contrast-enhanced power Doppler ultrasonography and conventional examination methods: the value of diagnostic predictors of prostate cancer

OBJECTIVE

To investigate the value of three-dimensional contrast-enhanced power Doppler ultrasonography (3D-CE-PDU) in the diagnosis of prostate cancer and to compare 3D-CE-PDU with digital rectal examination (DRE), prostate-specific antigen (PSA) levels, grey-scale ultrasonography (GSU) and PDU.

PATIENTS AND METHODS

The study comprised 30 patients with localized prostate cancer scheduled to undergo radical prostatectomy and 29 with clinical BPH scheduled to undergo transurethral microwave thermotherapy. The 3D-CE-PDU examinations were carried out using 2.5 g of microbubble ultrasound contrast medium; the images were stored digitally to allow off-line analysis. All the reconstructed 3D images of the prostate were evaluated blindly in random order by two investigators (one expert and one novice). The images were scored according to asymmetry (0-2) and vessel distribution (0-3). Marked asymmetry (2) and/or a focal increase in vascularity (> 2) were considered as suspicious for prostate malignancy. Diagnostic predictions using the DRE, PSA level, GSU, PDU, 3D-CE-PDU and their combinations were investigated using receiver operating characteristic (ROC) curves.

RESULTS

True-positive and true-negative rates of the 3D-CE-PDU were 87% (26/30) and 79% (23/29), respectively, for the expert observer. The sensitivity of 3D-CE-PDU was higher than that of DRE, GSU and PDU, but not PSA level, and the specificity was lower, again except for PSA level. However, when compared with those of the other modalities in single-test evaluations, 3D-CE-PDU, and a combination of 3D-CE-PDU and PSA level, had the largest area under the ROC curve (0. 830 and 0.933, respectively). The diagnostic agreement between the examiners was 76% (Cohen kappa statistic, 0.5).

CONCLUSION

In this selected group of patients, 3D-CE-PDU alone was a better diagnostic tool than the DRE, PSA level, GSU or PDU alone. The most suitable diagnostic predictor for prostate cancer was a combination of 3D-CE-PDU and PSA level.

The application of three-dimensional contrast-enhanced ultrasound to measure volume of affected tissue after HIFU treatment for localized prostate cancer

INTRODUCTION

Adequate monitoring of volume and location of affected tissue might provide helpful information when performing localized ablative therapy for prostate cancer. We hypothesize that the change in blood flow patterns after therapy in comparison to the blood flow pattern prior to therapy can be used to locate and quantify the amount of affected tissue due to the therapy. We describe the use of three-dimensional contrast-enhanced power Doppler ultrasound (3D-CE-PDU) to determine its additive value to visualize the extent of tissue defects created by high-intensity focused ultrasound (HIFU) in correlation with the histopathology of the prostatectomy specimen.

MATERIALS AND METHODS

Nine patients with biopsy-proven localized prostate cancer, who gave informed consent, were included in the protocol. HIFU treatment was performed 1 week in advance of radical retropubic prostatectomy (RRP) as part of a protocol to study the value of HIFU treatment as local ablative therapy for clinical T(1-2)N(0)M(0) prostate carcinoma. 3D-CE-PDU was performed 1 day prior to unilateral HIFU treatment of the affected lobe on biopsy indication and 1 day before RRP using 2.5 g Levovist((R)) (Schering AG, Germany) microbubble ultrasound contrast agent and a Kretz((R)) Voluson 530D ultrasound scanner (Kretztechnik AG, Austria). Ultrasound data and pathology whole-mount sections were stored digitally to allow off-line processing. Human interpretations of HIFU measurements in three-dimensional ultrasound data were based on gray-scale information (local increase in gray level) in combination with power Doppler mode (absence of blood flow). Histopathological analysis of the whole-mount section revealed a broad band of hemorrhagic necrosis in the HIFU-treated area. Using both the ultrasound data and the pathology sections, the total volume of the prostate and of the HIFU-treated area was measured, and relative volumes were obtained.

RESULTS

Visual inspection of the three-dimensional reconstruction of contrast-enhanced Doppler measurements revealed the HIFU-affected prostate tissue by the absence of a blood flow pattern. Paired t tests of the relative HIFU volume indicated that Doppler results (mean 21.7%, SD +/-10.8%) differed from the pathology results (mean 32.6%, SD +/-16.0%), but a good correlation was found between the relative pathology HIFU volume (Pearson correlation r = 0.94, p<0.0015) and mean 3D-CE-PDU HIFU. Closer inspection of the pathology specimen revealed that the outer ring of the macroscopic hemorrhagic necrosis overestimated the actually dead tissue. On microscopy, the border of dead tissue appeared to be 1-2 mm inside the macroscopically identified red hemorrhagic band. 3D-CE-PDU HIFU volumes indicated by the single observers were not statistically different and correlated very well (Pearson correlation r = 0.98, p<0.001).

CONCLUSION

The results illustrate that 3D-CE-PDU is a promising method to determine the size of the defect of HIFU ablative therapy for prostate carcinoma. The absence of blood flow indicated by three-dimensional power Doppler ultrasound images reflects affected tissue after HIFU treatment, and volume measurements of these areas can quantify the amount of affected tissue.

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.