D. zur Nedden

Intraurethral ultrasound: diagnostic evaluation of the striated urethral sphincter in incontinent females

Abstract. The aim of our study was to evaluate the striated urethral sphincter (rhabdosphincter) in incontinent females by means of intraurethral ultrasound (IUUS). Thirty-four incontinent and 11 continent female patients were examined by means of 12.5-MHz endoluminal ultrasound (US). The distance between the inner contour of the sphincter muscle and the US catheter was measured in the contracted and the non-contracted condition. The US findings were correlated with those obtained by urodynamic studies. Partial or complete loss of sphincter function was detected in patients with stress urinary incontinence (SUI). Reduced sphincter function was not observed in patients with urge incontinence and continent volunteers. The findings on US were found to correlate well with the grade of SUI. The IUUS technique offers the benefit of direct visualization of the sphincter mechanism. Therefore, endoluminal US may become an important adjunct in the diagnostic evaluation of SUI and will possibly provide new insights for a better therapeutic strategy.

Age-Related Changes in Resistive Index Following Extracorporeal Shock Wave Lithotripsy

PURPOSE Changes in intrarenal vascular resistance after extracorporeal shock wave lithotripsy (ESWL*) were studied with Doppler ultrasound techniques. MATERIALS AND METHODS In 76 patients the resistive index was measured at an interlobar artery before and after ESWL in the treated and contralateral kidneys. The resistive index levels were compared to N-acetyl-beta-D-glucosaminidase levels in 40 patients. RESULTS We found an age-related positive linear correlation between post-therapeutic resistive index increases and patient age. N-acetyl-beta-D-glucosaminidase levels were also elevated after ESWL but these elevations were not age-related. CONCLUSIONS Elderly patients have a higher risk of post-ESWL renal tissue damage.

MRI findings in cerebral fat embolism

Abstract. The purpose of this retrospective study was to demonstrate the MRI features of cerebral manifestations in patients with fat embolism syndromes in comparison with cerebral CT (CCT). Magnetic resonance imaging was performed according to standard protocols revealing multiple small non-confluent hyperintense intracerebral lesions larger than 2 mm on proton-density and T2-weighted images to various extents in three of four patients with clinically suspected cerebral fat embolism. Cerebral CT was negative in all patients. Our findings confirm that MRI can detect cerebral fat embolism with a higher sensitivity than CCT. Thus, MRI should be the first choice for imaging of cerebral fat embolism.

Bone mineral densitometry in dialyzed patients: quantitative computed tomography versus dual photon absorptiometry.

Reduced bone mineral density (BMD) increases risk of fractures, thus making it necessary to monitor patients suffering from chronic renal failure and consecutive disturbance of bone metabolism. In order to evaluate the reliability of available methods, bone mineral density of the lumbar spine assessed with single energy computed tomography (QCT) was compared with bone mineral density of the lumbar spine, femoral neck, Wards triangle and trochanteric region measured by dual energy photon absorptiometry (DPA) in 45 hemodialyzed patients with a mean hemodialysis duration of 35 +/- 26 months (SD). Depending on the measurement site and method 4-34% of dialyzed patients suffered from reduced BMD (z-score < -2). The highest correlation (r = 0.61, p < 0.01) was found between QCT of the spine, trabecular bone, and DPA of Wards triangle. One year after baseline measurement bone mineral density was reassessed after randomization to either QCT or DPA in 14 and 18 patients, respectively. Whereas lumbar spine and femoral neck did not change, mean BMD showed a decrease at the measurement sites of Wards triangle (DPA), trochanteric region (DPA) and trabecular bone of the spine (QCT), which, however, was statistically not significant. Cortical BMD of the spine assessed with QCT showed an increase. Although there is some reduction in bone density at most sites in hemodialyzed patients, no significant bone loss could be demonstrated over the course of 1 year.

Blood pressure changes after extracorporeal shock wave nephrolithotripsy: prediction by intrarenal resistive index

In order to identify a high-risk group for the development of arterial hypertension after extracorporeal shock wave nephrolithotripsy (ESWL), we correlated the increase in renovascular resistance induced by ESWL in 79 normotensive patients with changes in arterial blood pressure occurring 20 (+-3) months after therapy. Renal vascular resistance was measured as resistive index (RI) by duplex Doppler sonography in both kidneys. Mean RI before treatment was 0.620±0.035 (SD). After treatment, we observed a significant and age-dependent increase in the RI in the treated kidney to 0.673 ± 0.06. Of the patients with a post-ESWL RI> 0.690, 39% developed hypertension. Posttherapy RI values surpassing 0.690 showed a 0.8 sensitivity and a 0.7 specificity in predicting arterial hypertension. Intrarenal Doppler ultrasound (US) is useful to find the high-risk group for arterial hypertension after ESWL.

Virtual computed tomography colonoscopy: artifacts, image quality and radiation dose load in a cadaver study.

Abstract. The purpose of our study was to evaluate the interdependency of spatial resolution, image reconstruction artifacts, and radiation doses in virtual CT colonoscopy by comparing various CT scanning protocols. A pigs colon with several artificial polypoid lesions was imaged after air insufflation with helical CT scanning using 1-, 3-, and 5-mm collimation, and pitch values varying from 1.0 to 3.0. Virtual endoscopic images and “fly through” sequences were calculated on a Sun Sparc 20 workstation (Navigator Software, GE Medical Systems, Milwaukee, Wis.). Several reconstruction artifacts as well as overall image quality were evaluated by three independent reviewers. In addition, radiation doses for the different CT protocols were measured as multiple-scan average dose using a 10-cm ion chamber and a standard Plexiglass body phantom. Generally, image quality and reconstruction artifacts were less affected by pitch values than by beam collimation. Thus, narrow beam collimation at higher pitch values (e. g. 3 mm/2.0) seems to be a reasonable compromise between quality of virtual endoscopic images and radiation dose load.

Three-dimensional computed tomography of the reconstructed lower urinary tract: technique and findings.

Abstract. The aim of this pilot study in 54 patients was to improve the visualization of the anatomy and postoperative changes in the pelvic topography after bilateral ureteroileal urethrostomy, using surface rendering of electron beam CT (EBCT) data for the 3D display. Fifty-four patients (39 men and 15 women) were scanned with an EBCT unit between 3 and 110 months after performing orthotopic ureteroileal urethrostomy (“Hemi-Kock”) or ureteroileal rectosigmoidostomy. Various parameters and spatial viewing points were used in the 3D reconstruction, which was performed interactively on external workstations with commercially available software. The anti-reflux nipple was visualized as a distinct structure in all patients. In 8 patients with an interval of more than 12 months between surgery and CT, the pouch had developed an ovoid shape almost indistinguishable from the original bladder. The segmented data sets were partly animated to display the anatomy as virtual endoscopy. Three-dimensional depiction and virtual endoscopy of the neobladder using EBCT are a new way of imaging the postoperative anatomy. Its clinical efficacy in the diagnosis of inconclusive postoperative morbidity, especially voiding problems, and planning of necessary therapy have to be the subject of further evaluation.

Transurethral/sonomorphologic evaluation of male external sphincter of urethra

Sonoenorphotogic criteria of male urethral external sphincter under normal and pathologic conditions were evaluated by direct visualization with endoluminal US and correlated with normal anatomy. Between October 1992 and August 1993 18 patients were examined prospectively. We used a 12.5 MHz interventional US machine eduipped with a Sonicat 9-French catheter system. In all cases the anatomic structure of the external male urethral sphincter was visualized and demonstrated not in the expected circular configuration, but rather in an “omega sign” of the muscle and fibers, functioning with retraction of the ventral and lateral parts of the muscle, surrounding the urethra. Disorders of muscular function were revealed in 8 cases, and 6 cases demonstrated scarring and thinning of the muscle. Endoluminal-US offers the possibility of direct visualization not only of the male external sphincter, but also of the contracting mechanism in cross-sectional view. An exact description of sonoanatorny and the pathoenorphologic correlation is more accurate. The method therefore has the benefit of better access to further therapeutic considerations.

Ultrasound and MRI in the diagnosis of penile induration (Peyronie's Disease)

Penile induration, a disease of connective tissue, requires the precise delineation and differentiation of inflammatory changes (plaques) for accurate therapy. Seventy two patients with clinically suspected Induratio penis plastica (IPP) underwent ultrasound examination between 1984 and 1991. In 37 patients (aged 18 to 80) the diagnosis was proven by ultrasound. Out of this group 27 patients were examined with magnetic resonance imaging (MRI), 15 of them with additional intravenous application of adolinium DTPA (Gd-DTPA). All examinations were performed within four weeks. The results showed, that ultrasound was able to detect plaques and changes of the tunica albuginea in all 37 cases, but MRI was more sensitive in the detection of possible inflammatory change (T2-prolongation and moderate Gd-DTPA enhancement in gradient-echo sequences.MRI revealed inflammatory changes in 22 of 27 examined patients while ultrasound detected only nine such cases out of 37. Ultrasound is the method of choice in diagnosing IPP, due to the overall sensitivity to plaques and changes in the tunica. On the other hand MRI offers valuable additional information with respect to inflammatory changes particularly after Gd-DTPA. Therefore MRI has the potential to improve therapeutic planning and should be used in monitoring therapeutic effects.

Crossing Vessels at the Ureteropelvic Junction: Detection With Contrast-Enhanced Color Doppler Imaging

PURPOSE To investigate the feasibility of imaging crossing vessels at the ureteropelvic junction (UPJ) preoperatively by means of contrast agent-enhanced color Doppler imaging (CDI). MATERIALS AND METHODS Twenty-nine patients (13 female patients, 16 male patients; age range, 17-76 years; mean age, 45 years) with symptomatic UPJ obstruction were examined with CDI before and after intravenous infusion of the contrast agent. The type (i.e., arterial or venous) and position of the vessel relative to the UPJ (i.e., anterior or posterior) were assessed. The CDI findings were correlated with the surgical findings at laparoscopic pyeloplasty. RESULTS Among the 29 patients, crossing vessels were detected with nonenhanced CDI in 15 patients, with enhanced CDI in 22 patients, and with laparoscopy in 23 patients. Enhanced CDI depicted crossing vessels in 22 (96%) of the 23 laparoscopically confirmed cases compared with nonenhanced CDI, which depicted 15 (65%) of the 23 cases. The rate of detecting crossing vessels increased significantly with use of the contrast agent (P < .016, McNemar test). CONCLUSION Compared with nonenhanced CDI, contrast-enhanced CDI significantly improves the detection of crossing vessels at the UPJ and is useful in the presurgical evaluation of UPJ obstruction.