Hessel Wijkstra

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.

Age and Bladder Outlet Obstruction Are Independently Associated with Detrusor Overactivity in Patients with Benign Prostatic Hyperplasia

BACKGROUND Detrusor overactivity is one known cause of lower urinary tract symptoms and has been linked to bladder storage symptoms (urgency, frequency, or urge incontinence). OBJECTIVE To determine clinical and urodynamic parameters associated with detrusor overactivity in patients with suspected benign prostatic hyperplasia. DESIGN, SETTING, AND PARTICIPANTS During 1993-2003, urodynamic investigations were performed in patients aged 40 yr or older and with lower urinary tract symptoms, benign prostatic enlargement, and/or suspicion of bladder outlet obstruction (maximum flow rate < 15 ml/s or postvoid residual urine > 50 ml). MEASUREMENTS Detrusor overactivity was defined according to the new International Continence Society classification (2002) as involuntary detrusor contractions during cystometry, which may be spontaneous or provoked, regardless of amplitude. The Schäfer algorithm was used to determine bladder outlet obstruction. RESULTS In total, 1418 men were investigated (median age: 63 yr) of whom 864 men (60.9%) had detrusor overactivity. In univariate analysis, men with detrusor overactivity were significantly older, more obstructed, had larger prostates, higher irritative International Prostate Symptoms Score subscores, a lower voiding volume at free uroflowmetry, and a lower bladder capacity at cystometry. The prevalence of detrusor overactivity rose continuously with increasing bladder outlet obstruction grade. Multivariate analysis showed that only age and bladder outlet obstruction grade were independently associated with detrusor overactivity. After age adjustment, the odds ratios of detrusor overactivity compared to Schäfer class 0 were 1.2 for class I, 1.4 for class II, 1.9 for class III, 2.5 for class IV, 3.4 for class V, and 4.7 for class VI. CONCLUSIONS In patients with clinical benign prostatic hyperplasia, detrusor overactivity is independently associated with age and bladder outlet obstruction. The probability of detrusor overactivity rises with increasing age and bladder outlet obstruction grade.

Transrectal ultrasound of the prostate: innovations and future applications

PURPOSE We present a critical evaluation of the use of ultrasound for prostate disease examination in urological practice, and provide perspectives on ultrasound applications that may become important for the future evaluation of prostate problems. MATERIALS AND METHODS Based on an evaluation of clinical data in cases suspicious for prostatic malignancy, we addressed the apparent shortcomings of transrectal ultrasound for accurately diagnosing prostate cancer. Future applications presented in the literature were noted. RESULTS Evaluating the ultrasound data in cases suspicious for malignancy indicated that imaging has little advantage over digital rectal examination for detecting malignant areas. The new applications of ultrasound that hold great promise for use in the urology clinic include the injection of contrast agents to obtain information on blood supply, temperature estimation for the noninvasive assessment of temperature distributions during heat treatment and a therapeutic application for local treatment of prostate cancer. CONCLUSIONS While differential diagnosis with ultrasound appears to result in disappointing sensitivity and specificity values, its use in volume measurement and biopsy guidance is unquestioned. The development of new applications may improve the clinical value of ultrasound in urological practice. The application of ultrasound contrast agents for the detection and clinical staging of prostate cancer is especially promising. Future research will indicate whether the promise evolves in clinical applications.

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.

Results of the treatment of neurogenic bladder dysfunction in spinal cord injury by sacral posterior root rhizotomy and anterior sacral root stimulation

PURPOSE We evaluated the results of treatment of neurogenic bladder dysfunction in spinal cord injury by sacral posterior root rhizotomy and anterior sacral root stimulation using the Finetech-Brindley stimulator. MATERIALS AND METHODS In 52 patients with spinal cord lesions and urological problems due to hyperreflexia of the bladder complete posterior sacral root rhizotomy was performed and a Finetech-Brindley sacral anterior root stimulator was implanted. All patients were evaluated and followed with a strict protocol. A minimal 6-month followup is available in 47 cases. RESULTS Complete continence was achieved in 43 of the 47 patients with 6 months of followup. A significant increase in bladder capacity was attained in all patients. Residual urine significantly decreased, resulting in a decreased incidence of urinary tract infections. In 2 patients upper tract dilatation resolved. In 3 patients rhizotomy was incomplete and higher sectioning of the roots was necessary. One implant had to be removed because of infection. CONCLUSIONS The treatment of neurogenic bladder dysfunction in spinal cord injury by anterior sacral root stimulation with the Finetech-Brindley stimulator in combination with sacral posterior root rhizotomy provides excellent results with limited morbidity.

Contrast-Ultrasound Diffusion Imaging for Localization of Prostate Cancer

Prostate cancer is the most prevalent form of cancer in western men. An accurate early localization of prostate cancer, permitting efficient use of modern focal therapies, is currently hampered by a lack of imaging methods. Several methods have aimed at detecting microvascular changes associated with prostate cancer with limited success by quantitative imaging of blood perfusion. Differently, we propose contrast-ultrasound diffusion imaging, based on the hypothesis that the complexity of microvascular changes is better reflected by diffusion than by perfusion characteristics. Quantification of local, intravascular diffusion is performed after transrectal ultrasound imaging of an intravenously injected ultrasound contrast agent bolus. Indicator dilution curves are measured with the ultrasound scanner resolution and fitted by a modified local density random walk model, which, being a solution of the convective diffusion equation, enables the estimation of a local, diffusion-related parameter. Diffusion parametric images obtained from five datasets of four patients were compared with histology data on a pixel basis. The resulting receiver operating characteristic (curve area = 0.91) was superior to that of any perfusion-related parameter proposed in the literature. Contrast-ultrasound diffusion imaging seems therefore to be a promising method for prostate cancer localization, encouraging further research to assess the clinical reliability.

Clinical diagnosis of bladder outlet obstruction in patients with benign prostatic enlargement and lower urinary tract symptoms: development and urodynamic validation of a clinical prostate score for the objective diagnosis of bladder outlet obstruction

PURPOSE We attempted to improve the method of objective clinical evaluation of patients with benign prostatic enlargement and lower urinary tract symptoms. MATERIALS AND METHODS We compared the results of free uroflowmetry and transrectal ultrasound prostate size determination with those of pressure-flow analysis of bladder outlet obstruction in 871 consecutive elderly men. RESULTS Maximal flow, prostate size, and post-void residual and voided volumes were correlated with bladder outlet obstruction to derive a clinical prostate score. CONCLUSIONS Clinical prostate score shows a superior correlation with bladder outlet obstruction than isolated objective parameters or symptom scores.

Selective stimulation of sacral nerve roots for bladder control: A study by computer modeling

The aim of this study was to investigate theoretically the conditions for the activation of the detrusor muscle without activation of the urethral sphincter and afferent fibers, when stimulating the related sacral roots, Therefore, the sensitivity of excitation and blocking thresholds of nerve fibers within a sacral root to geometric and electrical parameters in tripolar stimulation using a cuff electrode, have been simulated by a computer model. A 3D rotationally symmetrical model, representing the geometry and electrical conductivity of a nerve root surrounded by cerebrospinal fluid and a cuff was used, in combination with a model representing the electrical properties of a myelinated nerve fiber. The electric behavior of nerve fibers having different diameters and positions in a sacral root was analyzed and the optimal geometric and electrical parameters to be used for sacral root stimulation were determined. The model predicts that an asymmetrical tripolar cuff can generate unidirectional action potentials in small nerve fibers. While blocking the large fibers bidirectionally. This result shows that selective activation of the detrusor may be possible without activation of the urethral sphincter and the afferent fibers.<<ETX>>

α-BLOCKADE IMPROVES SYMPTOMS SUGGESTIVE OF BLADDER OUTLET OBSTRUCTION BUT FAILS TO RELIEVE IT

PURPOSE We investigated the effect of the alpha-blockers alfuzosin, terazosin and tamsulosin on urodynamic parameters after 6 months of therapy. MATERIALS AND METHODS Between February 1992 and June 1998, 163 patients with lower urinary tract symptoms suggestive of bladder outlet obstruction were treated with alfuzosin (60), terazosin (66) and tamsulosin (37). Patients were evaluated with urodynamic studies, including pressure flow analysis, before treatment and after 6 months of therapy. Initially, all patients were also assessed by the International Prostate Symptom Score questionnaire and measurement of urinary flow rate. RESULTS The majority of patients had no clear improvement in obstructive parameters, regardless of the alpha-blocker used, as urethral resistance factor and detrusor pressure maximum flow rate decreased by only 4 cm. H2O. There was a clear subjective and statistically significant decrease in International Prostate Symptom Score and quality of life scores of 6 and 2 points, respectively. No relevant statistical difference was noted among the effects of the 3 alpha-blockers on relieving symptoms or improving urodynamic parameters of obstruction. CONCLUSIONS The alpha-blockers are effective for treating symptoms suggestive of bladder outlet obstruction in patients presenting with lower urinary tract symptoms but not for treating the obstruction.

Variability of Pressure-Flow Analysis Parameters in Repeated Cystometry in Patients with Benign Prostatic Hyperplasia

Urodynamic investigation becomes increasingly important in the diagnosis of bladder outflow obstruction in patients with benign prostatic hyperplasia. To date, different methods for evaluation of the pressure-flow relationship and quantification of the grade of obstruction are available. Models for pressure-flow analysis are briefly explained. The variability of the parameters is investigated by evaluation of 75 patients in whom 2 sequential voidings during urodynamic investigation were analyzed. The results showed that in 87% of these patients individual maximum flow differences of first and second voidings were less than 2 ml. per second. Individual detrusor pressure at maximum flow differences were less than 15 cm. water in 80% of these patients, while in 80% the intra-individual variation of the pressure-flow results was less than 15 cm. water for the minimal voiding pressure parameters (minimal urethral opening detrusor pressure and urethral resistance factor). For the pressure-flow parameter that defines the theoretical urethral lumen during voiding, the variation was less than 1.5 mm.2 in 84% of the patients. Patients with larger intra-individual differences are discussed. We concluded that the observed, aforementioned differences can be regarded as an indication of normal intra-individual variability of voiding during urodynamic investigation. This intra-individual variability, however, seldom leads to a change in the clinical grade of bladder outflow obstruction. We conclude that investigators involved in therapeutic trials of benign prostatic hyperplasia must be aware of this intra-individual variability of micturition, since this variability is greater than the refined scale of the pressure-flow analysis models.