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Objective: To evaluate the diagnostic accuracy of magnetic resonance urography (MRU) and determine its value for detecting ureteric obstruction., Methods: The electronic databases, including PubMed, Embase and the Cochrane library, were systematically searched for studies published throughout September 2018. The summary of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and receiver operating characteristic (ROC) curves was assessed to evaluate the diagnostic accuracy of MRU. Subgroup analyses were conducted based on the mean age of the included patients (adults or children)., Results: Eight studies with a total of 594 patients were included. The summary of the sensitivity and specificity of MRU for diagnosing ureteric obstruction was 0.94 and 0.87, respectively. Furthermore, the pooled PLR and NLR were 7.33 and 0.07, respectively. The DOR of MRU for detecting ureteric obstruction was 95.12. In addition, the summary of the area under the ROC of MRU was 0.96. Finally, the specificity, PLR and area under the ROC of MRU for diagnosing ureteric obstruction in adults were higher than children, while the sensitivity of MRU in adults was lower than children., Conclusions: These findings suggested a relatively high diagnostic value of MRU for detecting ureteric obstruction. Moreover, the diagnostic accuracy of MRU in adults was higher than in children. KEY MESSAGE Magnetic resonance urography (MRU) in detecting ureteric obstruction has relatively better sensitivity, specificity, PLR, NLR, DOR and AUC. The diagnostic value, including specificity, PLR and AUC of MRU in adults, was higher than in children, while the sensitivity of MRU in adults was lower than in children.

Background: Our aim was to compare CT images from native, nephrographic and excretory phases using image quality criteria as well as the detection of positive pathological findings in CT Urography, to explore if the radiation burden to the younger group of patients or patients with negative outcomes can be reduced., Methods: This is a retrospective study of 40 patients who underwent a CT Urography examination on a 192-slice dual source scanner. Image quality was assessed for four specific renal image criteria from the European guidelines, together with pathological assessment in three categories: renal, other abdominal, and incidental findings without clinical significance. Each phase was assessed individually by three radiologists with varying experience using a graded scale. Certainty scores were derived based on the graded assessments. Statistical analysis was performed using visual grading regression (VGR). The limit for significance was set at p = 0.05., Results: For visual reproduction of the renal parenchyma and renal arteries, the image quality was judged better for the nephrogram phase (p < 0.001), whereas renal pelvis/calyces and proximal ureters were better reproduced in the excretory phase compared to the native phase (p < 0.001). Similarly, significantly higher certainty scores were obtained in the nephrogram phase for renal parenchyma and renal arteries, but in the excretory phase for renal pelvis/calyxes and proximal ureters. Assessment of pathology in the three categories showed no statistically significant differences between the three phases. Certainty scores for assessment of pathology, however, showed a significantly higher certainty for renal pathology when comparing the native phase to nephrogram and excretory phase and a significantly higher score for nephrographic phase but only for incidental findings., Conclusion: Visualisation of renal anatomy was as expected with each post-contrast phase showing favourable scores compared to the native phase. No statistically significant differences in the assessment of pathology were found between the three phases. The low-dose CT (LDCT) seems to be sufficient in differentiating between normal and pathological examinations. To reduce the radiation burden in certain patient groups, the LDCT could be considered a suitable alternative as a first line imaging method. However, radiologists should be aware of its limitations.

Objectives: To assess dose area products (DAP) and effective doses (ED) of voiding cystourethrography (VCUG) in children using optimized protocols on a modern flat detector unit., Methods: DAP and ED were evaluated in 651 VCUG (316 girls, median age: 2.25 years) between 2009 and 2012. DAP was analyzed in relation to patient characteristics (gender, age, presence of pathological findings) and experience of performing physician using analysis of variance. ED values were estimated using adapted conversion factors from the literature. Diagnostic image quality was validated by two experienced physicians using a 3-point scale., Results: Median DAP/ED was 0.5 cGycm(2)/4.56 μSv (boys: 0.6 cGycm(2)/6.16 μSv; girls: 0.4 cGycm(2)/3.54 μSv). In 300 studies without pathologic findings DAP was 0.35 cGycm(2), whereas 351 studies with pathologic findings had a median DAP of 0.7 cGycm(2). No significant relationship between DAP and experience of radiologist was observed. Image validation resulted in an overall good to excellent rating., Conclusions: DAP and ED can be markedly reduced in paediatric VCUG performed with optimized protocols on modern equipment without a noticeable decrease in diagnostic image quality., Key Points: • Voiding cystourethrography is a comprehensive examination in diagnosing vesicoureteral reflux (VUR). • Radiation reduction is achieved in VCUG through modern equipment and optimized protocols. • Low-dose VCUG is possible without noticeable decrease in diagnostic image quality.

Objective: The purpose of this study was to compare CT image quality for evaluating urolithiasis using filtered back projection (FBP), statistical iterative reconstruction (IR) and knowledge-based iterative model reconstruction (IMR) according to various scan parameters and radiation doses., Methods: A 5 × 5 × 5 mm(3) uric acid stone was placed in a physical human phantom at the level of the pelvis. 3 tube voltages (120, 100 and 80 kV) and 4 current-time products (100, 70, 30 and 15 mAs) were implemented in 12 scans. Each scan was reconstructed with FBP, statistical IR (Levels 5-7) and knowledge-based IMR (soft-tissue Levels 1-3). The radiation dose, objective image quality and signal-to-noise ratio (SNR) were evaluated, and subjective assessments were performed., Results: The effective doses ranged from 0.095 to 2.621 mSv. Knowledge-based IMR showed better objective image noise and SNR than did FBP and statistical IR. The subjective image noise of FBP was worse than that of statistical IR and knowledge-based IMR. The subjective assessment scores deteriorated after a break point of 100 kV and 30 mAs., Conclusion: At the setting of 100 kV and 30 mAs, the radiation dose can be decreased by approximately 84% while keeping the subjective image assessment., Advances in Knowledge: Patients with urolithiasis can be evaluated with ultralow-dose non-enhanced CT using a knowledge-based IMR algorithm at a substantially reduced radiation dose with the imaging quality preserved, thereby minimizing the risks of radiation exposure while providing clinically relevant diagnostic benefits for patients.

Diagnostic imaging is routinely performed in small animals with lower urinary tract disease. Survey radiographs allow identification of radiopaque calculi, gas within the urinary tract, and lymph node or bone metastases. Cystography and urethrography remain useful in the evaluation of bladder or urethral rupture, abnormal communication with other organs, and lesions of the pelvic or penile urethra. Ultrasonography is the modality of choice for the diagnosis of most disorders. Computed tomography and magnetic resonance imaging are useful in evaluating the ureterovesical junction and intrapelvic lesions, monitoring the size of lesions, and evaluating lymph nodes and osseous structures for metastases., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Contrast-enhanced computed tomography urography has become possible because of the development of multidetector technology, which has evolved to try and increase its diagnostic efficacy and reduce the radiation exposure. This review highlights important aspects of computed tomography urography as an imaging technique.

Purpose: The urological Dyna-CT (Uro Dyna-CT) was established in clinical use for classical imaging as well as for interventional surgery. To evaluate whether irradiation artefacts may occur during interventional surgery, we analysed the impact of different instruments on 3D reconstruction in the Uro Dyna-CT., Materials and Methods: Ten different endourological instruments [ureterorenoscope (URS)-fibrescope, percutaneous nephrolithotomy (PCNL) working sheath] and accessory equipments such as ureteral catheter, guide wires and stents (DJ, MJ) were introduced in a porcine renal pelvis either retrograde via the ureter or transparenchymally. Subsequently, digital fluoroscopy, standard X-ray and an Uro Dyna-CT were performed. Three colleagues evaluated the image quality independent from each other., Results: There were basically no limitations regarding image quality in digital fluoroscopy and standard X-ray. In the Uro Dyna-CT, only with the URS fiberscope and the PCNL working sheath, small artefacts and irradiations were detected, whereas ureteric catheter with and without wire, as well as the hydrophilic guide wire, showed no artefacts at all. The remaining material demonstrated minimal artefacts, which did not affect the image quality., Conclusions: The Uro Dyna-CT can be used for all interventional endourological procedures using the common armamentarium and instruments without significant limitation of image quality. There are only minor limitations according a PCNL working sheath and the rigid URS. These instruments should be removed out of the examination field before performing the computed tomography and be replaced afterwards by using a safety wire.

Rationale and Objectives: To compare the image quality and diagnostic confidence of low-dose computed tomography (CT) of urololithiasis using filtered back projection (FBP) and iterative reconstruction techniques (IRT)., Materials and Methods: A 4.8 × 4.3 × 5.2 mm(3) uric acid ureteral stone was placed inside an anthropomorphic Alderson phantom at the pelvic level. Fifteen scans were performed on a 64-row dual-source CT system using different tube voltages (80, 100, and 120 kV) and current-time products (8, 15, 30, 70, and 100 mAs). Image reconstruction using FBP and IRT (iterative reconstruction in image space) resulted in 30 data sets. Objective image quality was evaluated by noise measurements. Effective doses were estimated for each data set with use of an established dosimetry program. Subjective image quality and confidence level were rated by two radiologists., Results: Noise was systematically lower for images reconstructed with IRT compared to FBP (55 ± 30 vs 65 ± 26 Hounsfield units; P = .004) for volume CT dose index values above about 0.6 mGy (or an effective dose of about 0.4 mSv for both sexes). For the 14 scans rated to have diagnostic image quality, the estimated effective doses ranged from 0.3 to 2.5 mSv for males and from 0.4 to 3.1 mSv for females. Subjective image quality and diagnostic confidence for IRT was not significantly better than those for FBP., Conclusions: In a phantom study for CT of urolithiasis, IRT improves objective image quality compared to FBP above a certain dose threshold. However, this does not translate into improved subjective image quality or a higher degree of confidence for the diagnosis of high-contrast urinary stones., (Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.)

Background: The development of a new urological intervention table now enables the application of an Artis zee ceiling Dyna-CT (Siemens, Erlangen, Germany) for interventional cross-sectional imaging and 3-D reconstruction of the urinary tract in the prone and supine positions (urological Dyna-CT)., Materials and Methods: We tested the feasibility of the urological Dyna-CT with the newly developed urological intervention table. The system was moved five times to enable 3-D reconstruction of the urinary tract of a test person in the prone and in supine positions., Results: Handling of the free floating table is easily possible during the intervention. We found no limitation of imaging system movement in any position of the test person., Conclusion: Apart from standard urological imaging such as fluoroscopy, intravenous pyelography or plain abdominal X-ray the urological Dyna-CT enables further imaging of the urinary tract. Fluoroscopy sequences can be stored as videos, and 3-D reconstructions of the urinary tract are possible with permanent patient access for any intervention. Extensive tests led to the technical approval of the system in urology.

Several promising clinical applications for dual-energy computed tomography (CT) in genitourinary imaging have been reported. Dual-energy CT not only provides excellent morphologic detail but also can supply material-specific and quantitative information that may be particularly useful in genitourinary imaging. Dual-energy CT has unique capabilities for characterizing renal lesions by quantifying iodine content and helping identify the mineral contents of renal stones, information that is important for patient care. Virtual unenhanced images reconstructed from dual-energy CT datasets can be useful for detecting calculi within the iodine-filled urinary collecting system, potentially reducing the need for an unenhanced scanning phase at CT urography. Although the underlying principles of dual-energy CT are the same regardless of scanner type, single-source dual-energy scanners with fast kilovoltage switching differ from dual-source dual-energy scanners both in image data acquisition and in processing methods; an understanding of these differences may help optimize dual-energy CT genitourinary protocols. Dual-energy CT performed with a dual-source scanner or with a single-source scanner with fast kilovoltage switching also has some important limitations. Further advances in scanning protocols and refinement of processing techniques to reduce image noise may lead to more widespread use of dual-energy CT., (© RSNA, 2012.)

Purpose: The purpose of this study was to assess the safety and feasibility of MR-guided percutaneous nephrostomy (PCN) using a 1.0 Tesla open MR-scanner with fast dynamic imaging., Methods: Twenty-five patients with failed ultrasonographic insertion due to various reasons, such as nondilated pelvic systems, obesity, and parapelvic cysts, were investigated., Results: In summary, 35 nephrostomy procedures were performed; 15 patients received monolateral and 10 patients bilateral placement. For guidance and monitoring, fast T2w single-shot-TSE imaging in a fluoroscopic mode in two orthogonal planes was used to guide the insertion of the needle into a predetermined calyx in freehand technique. Nephrostomy was inserted via Seldinger-technique. The procedure was regarded as technically successful if the placement of the catheter provided adequate drainage of the collecting system. Demonstration of an intrapelvic position of the catheter was verified by antegrade pyelography using T1w GRE imaging after injection of diluted Gd-DTPA into the collecting system. Under the experimental conditions of the study, the time for the complete procedure was 30 (range, 23-39) min. Puncture and placement of the nephrostomy was performed in 5 (range, 3-10) min on average., Conclusions: Our results demonstrated a pinpoint puncture of the pelvic system in a reasonable timeframe even in patients with difficult conditions, suggesting that MR-guided PCN using the open 1 Tesla system can be assessed as a reliable, fast, and safe method applicable in the clinical routine setting.

Purpose: We evaluated the feasibility of a using urine sensor for voiding cystourethrography (VCUG) and its implications for fluoroscopy time reduction., Materials and Methods: Institutional Review Board approved the study protocol. Study population included children less than 5 years old referred to our institution for VCUG. Patients with known vesicoureteral reflux or any pacing device were excluded from the study. The urine sensor consists of an electrode that senses the fluid, an electrical circuit and an indicator to provide visual signal. The urine sensor electrode was placed on the medial thigh in the proximity of the catheter close to the urethral opening, but without direct contact to it. A standard VCUG examination was performed with retrograde filling of the urinary bladder. Once the bladder was full, fluoroscopy of the voiding stage was initiated when the indicator blinked. Peak kV and fluoroscopy time were recorded., Results: Seven patients underwent VCUG with urine sensor and 22 patients without urine sensor. The urine sensor provided a reliable indication of voiding onset. The fluoroscopy time was significantly shorter with urine sensor use (1.99 min) than without urine sensor use (4.33 min) (p=0.001). In patients with normal VCUG, fluoroscopy time was also significantly shorter with urine sensor use (2.13 min) than without urine sensor use (4.39 min) (p<0.001)., Conclusion: VCUG studies with the help of the urine sensor are feasible and its use may result in significant reduction in fluoroscopy time., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Objectives: Digital tomosynthesis is a new digital technique based on conventional X-ray tomography. It acquires multiple low-dose projections during a single sweep of the X-ray tube, which are reassembled to provide high-resolution slices at different depths. Suggested uses include visualisation of pulmonary nodules, mammography, angiography, dental imaging and delineation of fractures. This study aims to evaluate its potential role as part of an intravenous urogram (IVU) by assessing the diagnostic quality in imaging the kidneys in clinical practice., Methods: 100 renal units from consecutive traditional IVU studies were retrospectively compared with 101 renal units imaged using digital tomosynthesis. These were scored for visualisation of the renal outline and collecting system, presence of a renal cyst or mass and overall diagnostic quality. Radiation doses were calculated., Results: 46.5% of traditional IVUs were found to be of diagnostic quality. The IVUs with digital tomosynthesis were of diagnostic quality in 95.5%. This represents a highly statistically significant difference (p<0.0001). There was also a statistically significant dose reduction, with a mean reduction of 56%, for the samples studied., Conclusion: Digital tomosynthesis offers a significant increase in the percentage of diagnostic quality tests for assessing renal pathology, compared with traditional IVU, and significantly reduces radiation. It also offers considerable advantages in ease and speed of imaging. For these reasons, in any situation where IVU is still being used to assess the kidneys, digital tomosynthesis is likely to be of considerable benefit in improving diagnostic quality.

Purpose: Evaluation of a handheld sonographic tool for the automatic estimation of bladder volume in comparison with conventional sonography in children under clinical conditions., Materials and Methods: 139 children (age: 30 days - 17 years) were examined with both conventional sonography and the handheld scanning device BVI 6200. For conventional sonography two different formulas were used to calculate the bladder volume., Results: The mean error of the three methods was 22.4 % for the handheld tool, 37.4 % for the most frequently used prolate ellipsoid formula in conventional sonography, and 23 % for an alternative formula recommended in the literature. In 19 cases the first automated sonography scan showed a false-negative result (empty bladder), while the automatically calculated volumes were between 17 and 60 ml in 5 cases of empty bladder. In one of these cases a megaureter and in another an ovarian cyst were detected by conventional ultrasound., Conclusion: Since pathologies are not visualized and can be misinterpreted as a nonempty bladder, the automated method should only be used in follow-up studies. In every case automated volumetry should be performed repeatedly to avoid false-negative results., (A A Georg Thieme Verlag KG Stuttgart A New York.)

With the increasing use of computed tomography (CT) for urography examinations, the indications for 'conventional' projection urography have changed and are more focused on high-contrast details. The purpose of the present study was to optimise the beam quality for urography examinations performed with a Gd(2)O(2)S:Tb flat-panel detector for the new conditions. Images of an anthropomorphic phantom were collected at different tube voltages with a CXDI-40G detector (Canon Inc., Tokyo, Japan). The images were analysed by radiologists and residents in a visual grading characteristics (VGCs) study. The tube voltage resulting in the best image quality was 55 kV, which therefore was selected for a clinical study. Images from 62 patients exposed with either 55 or 73 kV (original tube voltage) at constant effective doses were included. The 55-kV images underwent simulated dose reduction to represent images collected at 80, 64, 50, 40 and 32 % of the original dose level. All images were included in a VGC study where the observers rated the visibility of important anatomical landmarks. For images collected at 55 kV, an effective dose of approximately 85 % resulted in the same image quality as for images collected at 73 kV at 100 % dose. In conclusion, a low tube voltage should be used for conventional urography focused on high-contrast details. The study indicates that using a tube voltage of 55 kV instead of 73 kV for a Gd(2)O(2)S:Tb flat-panel detector, the effective dose can be reduced by approximately 10-20 % for normal-sized patients while maintaining image quality.

Objective: The purpose of this study was to investigate the feasibility of performance of MDCT urography with low tube voltage and an adaptive noise reduction filter., Subjects and Methods: Thirty-one patients underwent excretory phase (300 seconds after administration of 100 mL of iopamidol) 40-MDCT of the urinary tract at 120 and 80 kVp. The 80-kVp images were postprocessed with an adaptive noise reduction filter. Using a 3-point scale for homogeneity of the urinary tract and sharpness of contour, streak artifacts, and overall image quality, two radiologists evaluated coronal multiplanar reconstruction images generated from 120-kVp, unfiltered 80-kVp, and filtered 80-kVp images. Attenuation values of the abdominal aorta, renal pelvis, renal cortex, psoas muscle, vertebral body, and retroperitoneal fat and image noise of the psoas muscle were measured. The effective radiation dose was estimated for each patient., Results: At visual evaluation of images of the upper urinary tract, the quality of filtered 80-kVp images was comparable with that of 120-kVp images. At evaluation of images of the lower urinary tract, however, filtered 80-kVp images were of inferior quality. Except for those of fat tissue, attenuation values were significantly higher on 80-kVp than on 120-kVp images (paired Student's t test, p < 0.01). Noise values did not differ significantly between 120- and filtered 80-kVp images (Dunnett test, p = 0.37). The mean effective doses for 120- and 80-kVp scans were 7.0 and 2.9 mSv., Conclusion: MDCT urography is feasible with a low-tube-voltage technique and an adaptive noise reduction filter. The technique allows reduction in radiation dose without marked degradation of image quality and can be used in clinical assessment of the renal collecting system and upper ureter. For evaluation of the pelvic ureter and urinary bladder, however, image quality is not sufficient, and a compensatory increase in tube current may be necessary.

Background: Retrograde urethrography is considered the gold standard for evaluating stenosis or urethral disease., Purpose: To describe the clamp method for optimizing retrograde urethrography (RUG) using a perfected device and a drip infusion system. material and methods: RUG was performed in 42 patients with a mean age of 63.4+/-16.5 years suspected of having urethral stenosis. The modifications to the device are shown, and the steps of the technique described. The intensity of pain from both catheterization and external compression was measured on a visual analog scale (VAS)., Results: All the RUG examinations were conducted satisfactorily. The use of the drip infusion system enabled visualization of the posterior urethra in 97.6% of cases, and bladder repletion was achieved in 95.2% of cases. The urethrograms revealed images of stenosis in 31 patients. With catheterization the mean pain intensity registered by VAS was 0.7+/-0.6 (SD), whereas with external compression the mean pain intensity was 0.06+/-0.02 (SD)., Conclusion: The clamp method and drip infusion system used in this study are efficient and reduce patient discomfort. The procedure makes it possible to assess cases with stenosis close to the meatus that are difficult to manage with the conventional method.

Background: A hypothetical advantage of the da Vinci console is its ability to integrate multiple visual data sources. Current platforms for augmented reality surgery fuse pre-operative radiographic studies but are limited with their ability to update with intra-operative imaging. The aim of our study was to evaluate the feasibility of real-time radiographic image overlay with current technology., Methods: S-video composite output from a fluoroscopic C-arm was superimposed onto the video output of the da Vinci device. Image superimposition disparity measurements were evaluated in a bench model. The feasibility of robotic dissection assisted by real-time cholangiogram and intravenous pyelogram was evaluated., Results: Image alignment resulted in a radiographic blind spot and image disparity with severely limited application in an in vivo model., Conclusions: External collisions of the robotic device and visual disparity in multiple planes negate the current implementation of fluoroscopic overlay and will require more elegant methods of computer-assisted registration.

The time-sequence videotape-analysis methodology, developed [Sulieman et al., Radiology 178, 653-658 (1991)] for use in tissue dose estimations in adult fluoroscopy examinations and utilized [Bolch et al., Med. Phys. 30, 667-680 (2003)] for analog fluoroscopy in newborn patients, has been extended to the study of digital fluoroscopic examinations of the urinary bladder in newborn and infant female patients. Individual frames of the fluoroscopic and radiographic video were analyzed with respect to unique combinations of field size, field center, projection, tube potential, and tube current (mA), and integral tube current (mAs), respectively. The dosimetry study was conducted on five female patients of ages ranging from four-days to 66 days. For each patient, three different phantoms were utilized: a stylized computational phantom of the reference newborn (3.5 kg), a tomographic computational phantom of the reference newborn (3.5 kg), and (3) a tomographic computational phantom uniformly rescaled to match patient total-body mass. The latter phantom set circumvented the need for mass-dependent rescaling of recorded technique factors (kVp, mA, mAs, etc.), and thus represented the highest degree of patient specificity in the individual organ dose assessment. Effective dose values for the voiding cystourethrogram examination ranged from 0.6 to 3.2 mSv, with a mean and standard deviation of 1.8+/-0.9 mSv. The ovary and colon equivalent doses contributed in total approximately 65%-80% of the effective dose in these fluoroscopy studies. Percent differences in the effective dose assessed using the two tomographic phantoms (one fixed at 3.5 kg with rescaled technique factors rescaled and one physically rescaled to individual patient masses with no adjustment of recorded technique factors) ranged for -49% to +15%. Percent differences in effective dose found using the 3.5 kg stylized phantom and the 3.5 kg tomographic phantom, both with patient-specific rescaling of technique factors, ranged from -10% to +17%. These differences are due in part to a reduced ovary dose in the tomographic phantom for right posterior oblique (RPO) views when compared to those seen in the stylized phantom.

Purpose: To compare radiation doses given to patients undergoing IVU (intravenous urography) before and after digitalization of our X-ray department., Material and Methods: IVU examinations were monitored with dose area product meters before and after the X-ray department changed to digital techniques. The first step was a change from film-screen to storage phosphor plates, while the second step involved changing to a flat panel detector. Forty-two patients were included for the film-screen situation, 69 when using the storage phosphor plates, and 70 using the flat panel detector., Results: A dose reduction from 41.8 Gycm2 to 31.5 Gycm2 was achieved with the first step when the film-screen system was replaced with storage phosphor plates. A further reduction to 12.1 Gycm2 was achieved using the flat panel detector., Conclusion: The introduction of the flat panel detectors made a considerable dose reduction possible.

Purpose: To investigate whether image quality in storage phosphor urography can be maintained when the X-ray tube voltage is significantly lowered to give a lower patient dose., Material and Methods: Initial phantom studies were used to establish exposure settings at 53 kV that gave signal-to-noise ratios for contrast media structures equivalent to those obtained at the reference kilovoltage of 69 kV. Dose area product and image quality, assessed by image quality criteria and visual grading, were then recorded for 44 patients drawn at random to be examined by either the standard or modified technique., Results: Absorbed dose could be reduced by more than 30% without any significant change in image quality in manually controlled exposures and by 13% in exposures controlled by AEC., Conclusion: It might be possible to lower the tube voltage in digital examinations involving contrast media as a means of lowering patient dose. The image display parameters need to be adjusted to maintain image quality.

With the recent introduction of multi-detector row helical computed tomography (CT), the radiologic evaluation of patients with urologic disease has changed rapidly. Two major approaches to CT urography have been developed. The first approach combines axial CT with timed excretory urography (EU) performed by using conventional radiography, digital radiography, or CT scanned projection radiography (SPR). This approach produces traditional projection urograms, and the timed imaging technique is familiar to radiologists and clinicians. Additional excretory phase CT can be performed when the EU findings are positive or indeterminate. Improved CT SPR processing technology produces radiographlike images, thus eliminating patient transportation between the CT and urography suites or the necessity for a CT suite with a ceiling-mounted x-ray tube and a modified CT tabletop for performance of EU. The second approach to CT urography combines axial CT with thin-section excretory phase CT. The near-isotropic volume data set enables creation of high-resolution two- and three-dimensional reformatted images. However, the increased amount of radiation and the time required for data manipulation are concerns. Further studies evaluating large numbers of patients with various urothelial abnormalities will be necessary to determine the optimal CT urography technique for clinical practice., (Copyright RSNA, 2004.)

Multi-detector row helical computed tomography (CT) offers considerable advantages in evaluation of the urinary tract. It has the potential to become the single imaging modality used for comprehensive evaluation and treatment planning of most conditions affecting the kidneys and urinary tract, making conventional diagnostic techniques such as intravenous urography and angiography nearly obsolete. This article illustrates important selected applications of multidetector CT in the evaluation of benign conditions of the kidneys and upper urinary tract, including evaluation of the renal arterial and venous anatomy in preparation for surgery, diagnosis of renal artery stenosis and aneurysms, assessment of the renal veins, imaging of inflammatory and infectious renal diseases and evaluation of selected benign pathologic processes of the urinary tract., (Copyright RSNA, 2004)

Hematuria can be well evaluated with a comprehensive contrast material-enhanced multi-detector row computed tomography (CT) protocol that combines unenhanced, nephrographic-phase, and excretory-phase imaging. Unenhanced images are obtained from the kidneys to the bladder and allow optimal detection of renal calculi, a common cause of hematuria. Renal parenchymal abnormalities, particularly masses, are best visualized on nephrographic-phase images, which also provide excellent evaluation of the other abdominal organs. Thin-section delayed images obtained from the kidneys to the bladder demonstrate the urinary tract distended with contrast material and are useful in detecting urothelial disease. Intravenous urography, ultrasonography, CT, retrograde ureterography and pyelography, cystoscopy, and ureteroscopy can all be used to evaluate patients with hematuria. In the past, a combination of several of these examinations was necessary to fully evaluate these patients. Now, however, this CT protocol may permit evaluation of hematuria patients with a single comprehensive examination, although more experience and data are needed to determine its efficacy in this setting., (Copyright RSNA, 2003)

A new technique is presented for retrograde urethrography (RGU) using a plastic adjustable clamp. The procedure was performed in 36 patients with suspected urethral stenosis. Mean age was 55.3 years. The device and the procedure are described. All the radiologic examinations of the urethra were carried out successfully. The urethrograms showed images of stenosis in 27 patients. The stenoses localized in the distal tip of the anterior urethra were clearly seen with this clamp system. This method enables evaluation of the cases with stenosis close to the meatus that are difficult or even impossible to visualize with the conventional method. When necessary, a finer catheter can be used. This clamp system is recommended for RGU. The technique is simple, effective, and well tolerated by patients.

Unlabelled: The leading cause of death in children is accidents. Severe craniocerebral trauma and injuries to the heart or major vessels are mainly responsible for immediate death. This phenomenon is also reflected in the increasing number of pediatric admissions for renal trauma., Material and Methods: From 1990 to 2000, the charts of 132 patients with renal injuries secondary to blunt and penetrating trauma in childhood are reviewed., Results: A total of 88 were male patients and 126 sustained blunt trauma (motor accidents, falls, etc.). Gross and microscopic hematuria were the most important finding at the time of presentation, and correlated with severe renal injury, and both were present in 122 cases. Intravenous pyelography and CT scan were the most useful diagnosis tools. Only 27 patients were managed operatively, the majority because of associated intra-abdominal injury., Conclusions: Intravenous pyelography remains the most cost-effective means of investigating renal injuries in a second-level hospital. Renal contusion and most laceration should be managed conservatively. Only few a renal transactions should be managed operatively.

An auxiliary CT tabletop was designed and manufactured such that radiographic images might be acquired, with use of a ceiling-mounted X-ray tube, without removing the patient from the CT table. The tabletop required no modifications to the original CT table housing and did not produce artifacts in the CT images. Radiographs obtained with the overhead X-ray tube and auxiliary tabletop demonstrated image quality equivalent to traditional radiographs.

The aim of this study was to investigate the image quality for a flat-panel amorphous silicon detector at various radiation dose settings and to compare the results with storage phosphor plates and a screen-film system. A CDRAD 2.0 contrast-detail phantom was imaged with a flat-panel detector (Philips Medical Systems, Eindhoven, The Netherlands) at three different dose levels with settings for intravenous urography. The same phantom was imaged with storage phosphor plates at a simulated system speed of 200 and a screen-film system with a system speed of 160. Entrance surface doses were recorded for all images. At each setting, three images were read by four independent observers. The flat-panel detector had equal image quality at less than half the radiation dose compared with storage phosphor plates. The difference was even larger when compared with film with the flat-panel detector having equal image quality at approximately one-fifth the dose. The flat-panel detector has a very favourable combination of image quality vs radiation dose compared with storage phosphor plates and screen film.

Purpose: To report on the diagnostic capabilities of dynamic digital urography in the evaluation of orthotopic ileal neobladders., Material and Methods: Ten male patients (aged 61.3 +/- 14.7 years) with orthotopic ileal neobladder (4 Studer, 4 Camey type II with spiralized ileal segment and 2 classic Camey type II) underwent dynamic digital urography using an angiographic unit (Philips DVI/ARC-A). Eight patients were asymptomatic and two presented mild nycturia. All patients should have undergone follow-up conventional urography, which was replaced, for the purposes of our study, by dynamic digital urography. The intestinal cleansing regimen usual for the double contrast barium enema was used in all the patients. Ninety mL of a nonionic iodinated contrast agent were administered i.v. with an automatic injector. After precontrast mask images, two postcontrast sequences were acquired 15 s and 30 min after the injection (each made of 20 images acquired every 10 seconds). Postprocessing consisted of digital image subtraction and videorecording., Results: Renal pelvis and calyceal systems were well visualized in 18/20 excretory systems. Eighteen of 20 ureters were visualized completely up to the ureteral jet, and two were only partially visualized. Calyceal, pyelic and ureteral enlargement with ureteral kinking were observed in a patient with classic Camey type II. High motility was seen in 11 ureters, moderate in 5 and mild in 4. The orthotopic ileal neobladder was well opacified in 8/10 patients. Effective peristalsis of the afferent ileal segment was seen in all the Studer type neobladders. Ureteral reflux was not observed in any patient., Discussion: After orthotopic ileal neobladder reconstruction, the most frequent complications include urinary leakage, intestinal obstruction, venous thrombosis, stenosis of the neobladder anastomoses, incontinence, cancer recurrence, stone formation. In the follow-up, many diagnostic tools are used: intravenous urography, retrograde cystography, urodynamic studies, transabdominal and transrectal ultrasonography. With dynamic digital urography the nephrographic evaluation was possible in all patients, as well as the evaluation of calyceal, pyelic and ureteral opacification and even ureteral peristalsis. Moreover, this diagnostic tool allows the morphofunctional dynamic study of the ureteral-neobladder anastomoses and of the orthotopic ileal neobladder, even evaluating the residual peristalsis of the detubularized ileal segment. A major drawback of the new method is the relatively high radiation dose given to the patient. A limitation of the study is the selection of a population of completely or nearly asymptomatic patients., Conclusions: Dynamic digital urography provides useful morphologic and functional information in the follow-up of patients with orthotopic ileal neobladder and could replace conventional urography in symptomatic patients.

Urinary symptoms in adolescents are common, particularly in females. Urinary tract infections (UTIs) cause many of these symptoms. For uncomplicated UTIs, both lower and upper tract, therapy is straightforward. Commonly used antibiotics are trimethoprim/sulfamethoxazole (TMP/SMX), cefixime, and ciprofloxacin (off-label use) for 3 days for lower tract infections and 10ñ14 days for upper tract infections. Adolescent UTIs are markers for sexual activity, just as UTIs in younger children are often markers for anatomic defects, e.g., congenital abnormalities. Adolescents with upper and lower UTIs often have concurrent sexual activity or a complication of that activity. Issues among adolescents with UTIs are more similar to those of young adults than to those of younger children. It is as important to counsel adolescents about sexual activity and its consequences as it is to treat the UTIs. All adolescents with UTIs should be queried for sexual activity; evidence of sexually transmitted diseases (STDs) should be sought; and counseling for STDs and responsible sexual activity is recommended. Complicated UTIs include those in patients who have grown into adolescence after a childhood of infections or who have anatomic abnormalities, recurrent infections, reflux and reflux nephropathy, spina bifida and neurogenic bladder, transplanted kidneys, diabetes, and urolithiasis. These patients require individualized medical programs, unique for their condition, history, and microbiology.

Purpose: To investigate the feasibility of reconstructing a virtual endoscopy from MR imaging data sets of the upper urinary tract., Method: The data obtained from 28 contrast-enhanced MR urographic examinations (5 normal; 23 pathologic) were post-processed to reconstruct a virtual ureterorenoscopy (VURS) using a threshold image segmentation. The visualization of the upper urinary tract was based on the acquisition of T1-weighted 3D gradient-echo sequences after intravenous administration of gadolinium-DTPA and a prior injection of low-dose furosemide., Results: The employed MR urography technique created in all 28 cases a complete and strong contrast enhancement of the urinary tract. These 3D sequence data allowed the reconstruction of a VURS, even when the collecting system was not dilated. The best accuracy was provided by the MR urography sequences with the smallest voxel size. Moreover, the data acquisition based on a breath-hold technique has proved superior to that using a respiratory gating. Inside the renal pelvis, all calices could be assessed by turning the virtual endoscope in the appropriate direction. The visualization of the ureteral orifices in the bladder was also possible. All filling defects that were diagnosed by MR urography could be evaluated from the endoluminal view using the VURS. The exact characterization of the lesions based only on the assessment of the surface structure was difficult., Conclusion: A virtual endoscopy of the upper urinary tract can be successfully reconstructed using the data sets of high-resolution 3D MR urography sequences.

Purpose: To enlarge the prostatic urethra with thermal coagulation with transrectal radio-frequency (RF) application in dogs., Materials and Methods: Eight aged dogs underwent RF ablation of periurethral prostatic tissue for 6 minutes. Eighteen-gauge electrodes were placed into the periurethral tissues with a transrectal approach and ultrasound (US) guidance. Prostatic and rectal temperatures were measured during RF application. US, conventional and computed tomographic (CT) retrograde urethrography (RUG), and CT were performed immediately (n = 8) and at 3-96 days (n = 6) after ablation. Histopathologic analysis was performed at sacrifice immediately (n = 2), at 28 days (n = 2), or at 3 months (n = 4) after treatment., Results: All procedures were successful with no complications and were performed in less than 30 minutes. Rectal mucosal temperature did not exceed 38 degrees C. Immediately after treatment, CT and US demonstrated 1.2-cm foci of altered periurethral tissue that corresponded to solid coagulated tissue at histopathologic analysis. By day 3, CT, RUG, and US demonstrated that these foci had begun to cavitate, resulting in enlargement of the urethra. Complete cavitation was demonstrated by day 28. Minimal reduction in the degree of urethral enlargement was noted by day 60, but narrowing, urethral strictures, or fistulas were not observed at 3 months. At histopathologic analysis, focal cavitary enlargement with at least doubling of the urethral diameter and with normal urothelium was noted in all dogs surviving at least 28 days., Conclusion: Transrectal RF urethral enlargement is feasible and safe in animals and merits investigation for alleviating urethral obstruction due to benign prostatic hyperplasia.

The purpose of this study was to present our initial experience with contrast-enhanced MR urography with a breath-hold three-dimensional imaging technique. We performed MR urographic studies in two pigs (four studies) and five human subjects using gadopentetate dimeglumine. The FISP sequence we used was the same as the one used for contrast-enhanced three-dimensional breath-hold angiography. MR three-dimensional urograms were obtained 7-24 minutes after the contrast injection with a dose as low as .03 mmol/kg. The calyces, renal pelves, and ureters were very well visualized. Three-dimensional MR urography can be acquired within a single breath-hold after administration of gadolinium chelates. This technique could become part of a protocol that could potentially lead to a single comprehensive diagnostic workup for suspected ureteral obstruction and gross hematuria.

Purpose: To assess the value of functional magnetic resonance urology for the noninvasive postoperative evaluation of renal transplants., Methods: A saturation inversion projection sequence allows the selective imaging of strongly T1 weighted signal from the MR contrast agent. A control slab leads to images comparable to conventional urography which can be acquired as a sequence with four images per minute., Results: 15 patients with urologic questionable findings after renal transplantation were studied. FMRU revealed in 6 patients normal findings, in 6 moderate dilatation of the renal pelvis without any urodynamic relevant obstruction. 3 pathologic findings, ureteral leak, ureteropelvic-junction obstruction and ureteral stenosis were diagnosed and consequently surgically treated. The imaging quality in all studies was diagnostic and urologically relevant., Conclusion: FMRU can be used as a noninvasive technique for the assessment of renal transplant in cases with suspicion of complication in the excretory system.

Objective: Determination of the proportion of the dose-area product caused by fluoroscopy at voiding cystourethrography in children, using digital image intensifier technology., Patients and Methods: Using computer-assisted dosimetry, we determined the dose-area product and the respective proportions of the dose-area product caused by fluoroscopy and radiography as well as the number of radiographs taken at a given examination of 40 children (8 children less than 2 years old, 15 children between 2 and 6 years old and 17 children between 6 and 15 years old)., Results: The computer software program correctly differentiated between fluoroscopy and radiography in 80% of cases. Incorrect results were primarily observed in newborns and young children. The total radiation dose ranged in relation to patient age from 22 to 651 cGy x cm2. Fluoroscopy was responsible for an average 78% of the applied radiation dose., Conclusion: Computer-assisted dosimetry is useful in determining the proportion of the dose-area product caused by fluoroscopy in older children undergoing voiding cystourethrography. When image intensifier technology is used, this accounts for more than 75% of the total radiation dose. The method is not suitable for use in small children.

Complications of voiding cystourethrography are infrequent. We report a rare complication of knotting of the catheter within the bladder, necessitating surgical removal of the catheter through the urethra.

Purpose: Optimization of image quality by use of digital luminescence radiography (DLR) in voiding cystoureterography (VCU) instead of a conventional screen film system., Patients and Methods: 53 patients with a suspected vesicouretral reflux were examined with a VCU in analogous and digital technique. The X-rays were taken in a sitting position while simultaneously measuring the bladder pressure. An intraindividual comparison was omitted for X-ray saving reasons. In the follow-up 3 patients were examined with the other system. Two radiologists and two urologists compared 60 VCU of 53 patients--30 VCU in conventional screen film and 30 in DLR technique presented in standard and edge-enhanced images--with regard to image quality according to 3-step score (A--good image quality, B--sufficient image quality, C--insufficient image quality)., Results: The 59 conventional films were scored 72 times with an A, 76 times with a B, and 72 times with a C, whereas the DLR films were scored 116 times with an A, 72 times with a B, and only 8 times with a C. Hereby the edge-enhanced images were the most useful for distinguishing the bladder shadow from the soft tissue of the thigh and for detecting reflux. Furthermore, the exposure dose when applying DLR could be decreased to 75% in grown-ups and to 57% in children without any significant loss of information., Conclusion: The DLR is highly superior to the conventional film screen system because of its relatively high tolerance towards wrong exposures, especially with respect of the sitting position during MCU. With the DLR we obtained 96% and with the conventional system only 63% films usable for diagnosis.

Tumor-induced dilatation of the urinary tract is difficult to diagnose in the distal part of the ureter, including the stenosis, by ultrasound and X-ray. Often on account of renal insufficiency and allergy, i.v.-contrast media cannot be used. The present study should show the suitability of fast T2-weighted (turbo-) spin-echo sequences (T2-TSE) for MR-urography (MRU). Seven patients (62.3 +/- 6.1 years) were examined in the coronal plane with T2-TSE sequence (TR = 4500 ms, TE = 160 ms) and an MRU was calculated by using the MIP method (maximal intensity projection). This technique enabled urogram-like morphological representation of dilated urinary tract including stenosis in 6 of 7 patients. Assuming a high magnetic field homogeneity, MRU by using a T2-TSE-sequence, without i.v.-contrast media administration, can visualize the urinary tract dilatation and localize tumor-induced stenosis.

Objective: In voiding cystourethrography, the urethral catheter may or may not be left in place during voiding. The main argument for removing the catheter is that the diagnosis of posterior urethral valves may be missed because the catheter can hold open the valve, efface it, and render it invisible. However, if the catheter does not prevent the diagnosis of urethral disease, it is preferable to leave it in place. The catheter makes it possible to repeat the procedure easily if necessary, and using it to drain the bladder provides information about ureteric obstruction in the presence of vesicoureteric reflux. Accordingly, the purpose of this study was to determine whether leaving the urethral catheter in place throughout voiding cystourethrography affects the efficacy of the procedure for the diagnosis of posterior urethral valves., Materials and Methods: Three radiologists reviewed the preoperative voiding cystourethrograms obtained in 48 boys who ranged in age from 1 day to 10 years old (mean, 1.5 years). All patients had a diagnosis of posterior urethral valves made at cystoscopy, which was used as the gold standard. The voiding cystourethrogram was obtained with a catheter in place during voiding in 28 (58%) of the 48 boys, without a catheter in 17 (35%), and with and then without a urethral catheter during the voiding phase of the study in three (6%)., Results: Posterior urethral valves were detected on 25 (89%) of the 28 voiding cystourethrograms obtained with a urethral catheter in place and in 15 (88%) of the 17 voiding cystourethrograms done without a urethral catheter. The five children in whom posterior urethral valves had been diagnosed by cystoscopy but were not detected on voiding cystourethrography had no dilatation of the posterior urethra nor any other evidence of obstruction; these were possibly false-positive cystoscopic diagnoses., Conclusion: Our results show that a urethral catheter does not obscure posterior urethral valves in boys and need not be removed routinely during the voiding phase of voiding cystourethrography.

To correct urination the authors used retrograde infusion urethrocystography (RIU) in 102 males. 57 of them had an urethral stricture. A novel urethrocystography device is proposed which facilitates the procedure and is more safe in relation to complication danger. The advantages of the modified RIU over routine one are demonstrated.

Urethral diverticula have proved to be a common cause of recurrent urinary tract infections in female subjects. Positive-pressure urethrography, mostly performed by means of double-balloon catheters, has hitherto been regarded as the method of choice for their detection. Unfortunately, the few existing commercial catheter devices have certain disadvantages, which have led to a lack of acceptance of this important technique and restricted its use. We therefore present an improved tool for positive-pressure urethrography and a synopsis of diagnostic visualization procedures for urethral diverticula in women.

Interdisciplinary use of extracorporeal shock-wave lithotripsy with sonographic or fluoroscopic guidance has become a routine procedure in clinical practice, for both urolithiasis and cholecystolithiasis. Therefore, newly developed systems with combined locating devices are gaining in importance. A primary sonographically guided lithotripter was extended by a mobile X-ray system. The results were compared with those obtained with a first-generation lithotripter. The results show that sufficient disintegration of stones throughout the urinary tract is possible with both systems. The retreatment rate with both lithotripters was 30% when stone size was comparable. No essential differences in treatment time, shockwave energy and pain were found. The easy localisation of radiolucent stones, convenient positioning of the patient and successful localisation of ureteral stones near to the spine are advantages of the MPL 9000 X. On the other hand, the technically simpler fluoroscopy system and greater ease of electrode changing are advantages of the HM3 Lithotripter. Altogether, differences in the application of the two systems are slight and insignificant except in special cases.

Radiology of the urinary tract has a great place in evaluating voiding dysfunction. The role of the radiologist is not limited to diagnosis of the sequelae of voiding dysfunction but he must provide information about causes, mechanisms and helps to provide a more accurate diagnosis. Projectional radiography (excretory urography, voiding cysto-urethrography) is still the best method of evaluation in spite of development of new imaging techniques (ultrasonography, computerized axial tomography, magnetic resonance imaging). Radiodynamic examination of the lower urinary tract is the best method of choice to study the complex functional problems involving those structures.