Assessment of clinically significant urolithiasis positivity rate using CT KUB for suspected renal colic.

BACKGROUND: Unenhanced low-dose computed tomography of the kidneys, ureter and bladder (CT KUB) is the gold standard diagnostic imaging modality in the assessment of suspected renal colic. As the radiation dose is not negligible, it is important to monitor the diagnostic yield of CT KUBs. The aim of this study is to evaluate the diagnostic yield of CT KUB studies performed for suspected renal colic in patients presenting to the emergency department. METHODS: A retrospective review was performed of 500 patients who underwent CT KUB for suspected renal colic over a seven month period from June 2019 to January 2020. Clinical information and imaging was reviewed for each patient. Statistical analysis was performed using GraphPad Prism 8 (GraphPad Software, San Diego, CA, USA). RESULTS: Forty-nine percent of patients in the series were female (248/500) and the mean age was 45. The positivity rate for obstructing ureteral calculus was 34% (169/500). Concerningly, there was a significantly lower positivity rate in females compared to males (19% versus 48%; p < 0.0001) which raises the issue of unnecessary radiation exposure to this cohort. In the 200 female patients who were negative for obstructing urolithiasis, the mean age was 43. Females also had a significantly higher rate of negative CT KUB (62% versus 37%; p < 0.0001) where no underlying alternative pathology was diagnosed. CONCLUSIONS: Women are less likely than men to have obstructing urolithiasis on CT KUB for suspected renal colic. This difference is not accounted for by a higher rate of alternative diagnoses among female patients. The findings of this study should prompt clinicians to exercise caution when considering this imaging modality in this patient cohort.

Three-fluorescence sensor for minute-time scale low-cost analysis of urinary oxalate in urolithiasis metabolic assessment.

Since oxalate plays an important role in the metabolic assessment of urolithiasis, there is need for convenient and efficient methods for oxalate detection. Herein, we report a three-signal fluorescence strategy for oxalate analysis based on the ability of oxalate to reduce Cu2+ to Cu+, and the ability of pyrophosphate-cerium coordination polymeric networks (PPi-Ce CPNs), cadmium telluride quantum dots (CdTe QDs), and N-Methyl Mesoporphyrin (NMM) to selectively detect Cu2+ and Cu+. The detection range was 100 nM to 1 mM, the turnaround time was 6 min, while the limits of detections for PPi-Ce CPNs, QDs and NMM as reporters were 25 nM, 10 nM and 40 nM, respectively. Visual detection of oxalate relied on color change in the solution, which could be observed using the naked eye. The fluorescent system was used for oxalate analysis in 44 urine samples (32 calcium oxalate stone patients, 12 controls without urolithiasis), and the results were consistent with clinical diagnosis and imaging data. Moreover, the visual system was used to analyze 8 urine samples (4 patients and 4 controls), and showed good consistency with clinical diagnosis and computed tomography imaging results. These findings suggest that the method has potential application for the metabolic assessment of urolithiasis.

Application of Digital Tomosynthesis in the Diagnosis of Urolithiasis: Comparison with MDCT.

Objective: To investigate the diagnostic value of digital tomosynthesis in urolithiasis compared with multidetector computed tomography (MDCT). Subjects and Methods: This study received the approval of institutional review board and obtained the informed consents of all subjects. Fifty patients with acute renal colic and hematuria from February 2014 to February 2015 were enrolled. They underwent both MDCT and digital tomosynthesis. Images were interpreted by two experienced radiologists, and inter-reader agreement was assessed. The diagnostic performance of urinary stones with digital tomosynthesis and MDCT was compared. The entrance surface dose (ESD) in MDCT and digital tomosynthesis for patients was measured and compared. Results: No significant difference was found between digital tomosynthesis and MDCT in the diagnosis of urinary stones (X2 = 1.357, p > 0.05). The ESD in digital tomosynthesis was lower than that in both routine-dose and low-dose MDCT for patients (p < 0.05). Conclusions: Digital tomosynthesis has great diagnostic value in urolithiasis. Compared with MDCT, digital tomosynthesis can significantly decrease ESD for patients and financial loan with a similar detection rate.

Increasing Use, Geographic Variation, and Disparities in Emergency Department CT for Suspected Urolithiasis.

PURPOSE: The aim of this study was to examine changing characteristics of utilization and potential disparities in US emergency department (ED) patients undergoing CT of the abdomen and pelvis (CTAP) for suspected urolithiasis. METHODS: A retrospective study was conducted among all patients from 2006 to 2015 with a primary diagnosis of suspected urolithiasis within the Nationwide Emergency Department Sample, the largest publicly available all-payer ED database in the United States. The annual numbers of ED visits for suspected urolithiasis and associated CTAP examinations per visit were determined. The compound annual growth rate for CTAP was calculated. Using multivariate logistic regression analyses, patient demographics and payer and hospital characteristics were evaluated as potential independent predictors of utilization. RESULTS: Nationwide, the number of ED visits per year for suspected urolithiasis increased from 1,057,119 in 2006 to 1,246,041 in 2014 (relative +17.9%), whereas the annual use of CTAP increased from 24.6% to 49.4% per visit (relative +100.8%; CAGR +8.0%). Multivariate analysis showed higher CTAP use associated with higher patient household income ZIP code quartile (odds ratio [OR] for wealthiest/poorest, 1.48), private payer (ORs, 1.21 versus Medicare and 1.22 versus Medicaid), Northeast geographic region (ORs, 5.07 versus Midwest, 4.16 versus West, and 1.77 versus South), hospital urban status (OR, 1.42), and nonteaching hospitals (OR, 1.20) (P < .05 for all). CONCLUSIONS: The relative use of CTAP in ED patients presenting with suspected urolithiasis doubled between 2006 and 2014 and showed marked geographic variation. Among ED patients with suspected urolithiasis, CTAP was more frequent in patients from higher household income ZIP codes, with private insurance, in the Northeast, and at urban and nonteaching hospitals.

Rapid kVp switching dual-energy CT in the assessment of urolithiasis in patients with large body habitus: preliminary observations on image quality and stone characterization.

PURPOSE: The purpose of this study was to investigate the image quality (IQ) considerations of rapid kVp switching dual-energy CT (rsDECT) in the assessment of urolithiasis in patients with large body habitus and to evaluate whether it allows stone characterization. MATERIALS AND METHODS: In this IRB-approved, HIPAA compliant retrospective study, 93 consecutive patients (M/F = 72/21, mean age 56.9 years, range 23-83 years) with large body habitus (> 90 kg/198 lbs) who underwent dual-energy (DE) stone protocol CT on a rapid kVp switching DECT scanner between January 2013 and December 2016 were included. Scan acquisition protocol included an initial unenhanced single-energy CT (SECT) scan of KUB followed by targeted DECT in the region of stones. Two readers evaluated both CT data sets (axial 5 mm 120 kVp/140 kVp QC/70 keV monoenergetic, material density water/iodine images and coronal/sagittal 3 mm images) for the assessment of image quality (Scores: 1-4) and characterization of stone composition (reference standard: crystallography). RESULTS: One hundred and five CT examinations were performed in 93 patients (mean body weight 105.12 ± 13.53 kg, range 91-154 kg), and a total of 321 urinary tract calculi (mean size-4.8 ± 3.2 mm, range 1.2-22 mm) were detected. Both SECT and targeted monoenergetic images were of acceptable image quality (mean IQ: 3.77 and 3.83, kappa 0.79 and 0.87 respectively). Material density water and iodine images had lower IQ scores (mean IQ: 2.97 and 3.09 respectively) with image quality deterioration due to severe photon starvation/streak artifacts in 20% (21/105) and 17% (18/105) scans, respectively. Characterization of stone composition into uric acid/non-uric acid stones was achieved in 93.14% (299/321) of calculi (mean size: 4.99 ± 3.3 mm, range 1.2-22 mm), while 7% (22/321) stones could not be characterized (mean size 3.03 ± 1.16 mm, range 1.6-6.4 mm) (p < 0.001). Most common reason for non-characterization was image quality deterioration of the material density iodine images due to severe photon starvation artifacts. On multivariate regression, stone size and patient weight were predictors of stone composition determination on DECT (p < 0.05). The transverse diameter had a weak negative correlation with stone composition determination, but it was not statistically significant. Stone characterization into uric acid vs. non-uric acid stones was accurate in 95% (n = 38/40) of stones in comparison with crystallography. CONCLUSION: In patients with large body habitus, rsDECT allowed characterization of most calculi (93%) despite image quality deterioration due to photon starvation/streak artifacts in up to 20% of material density images. Stone size and patient weight were predictors of stone composition determination on DECT, and small calculi in very large patients may not be characterized.

Sonographic assessment of urolithiasis in University of Abuja Teaching Hospital, Nigeria.

Background: Urolithiasis may result in many complications including renal failure. There is a paucity of documented scientific study on the prevalence of urolithiasis in the University of Abuja Teaching Hospital within the Federal Capital Territory, Nigeria. The aim of the study was to assess the prevalence of urolithiasis in patients undergoing ultrasound at University of Abuja Teaching Hospital. Materials and Methods: This study which adopted a survey approach was conducted at the Department of Radiology, University of Abuja Teaching Hospital between June 2014 and May 2015. A total of 2310 patients that underwent abdominopelvic ultrasound in the department who aged between 2 and 64 years and met the inclusion criteria participated in the study. They were recruited using a convenience (nonprobability) sampling technique. Data obtained were subjected to descriptive statistics and analyzed using Student's t-test. P < 0.05 was considered statistically significant. Results: A total of 2310 patients were scanned, 31 patients were sonographically identified with urolithiasis. The prevalence of urolithiasis was 13.4/1000. The mean age was 31.12 ± 3.69 years. There were 58.06% males and 41.93% females giving a male-to-female ratio of 1.3:1. The peak age of incidence was 21-50 years. Majority (22 [71%]) were located in the upper urinary tract, whereas 9 (27%) were in the lower urinary tract. The most common presenting symptoms were flank/loin pains (renal colic) noted in 12 (40%) patients, followed by hematuria in 4 (13.3%) patients. Conclusion: The prevalence of urolithiasis was 13.4/1000. This information can be utilized in formulating future health plans for prevention of urolithiasis in the hospitals within this locality.

RésuméInformations de base: L'urolithiasis peut résulter en beaucoup de complications y compris l'insuffisance rénale. Il y a manque d'études scientifiques documentées sur la prévalence de l'urolithiasis à l'Hôpital d'Enseignement Universitaire situé au territoire de la capitale fédérale du Nigéria. Le but de cette étude est d'évaluer la prévalence de l'urolithiasis sur les malades qui subissent l'ultrason à l'Hôpital d'Enseignement Universitaire d'Abuja. Matériaux et méthodes: Cette recherche qui a adopté l'approche d'enquête à l'Hôpital d'Enseignement Universitaire a été faite au Département de Radiologie de l'Hôpital d'Enseignement Universitaire d'Abuja entre juin 2014 et mai 2015. Âgés de 2 et 64 ans, 2.310 de malades au total qui ont subi l'ultrason abnomino-pelvien, ayant répondu aux critères d'inclusion, étaient examinés dans le département. Ils ont été examinés en servant de la technique d'échantillonage de commodité (non probabilité). Les données obtenues ont été soumises aux statistiques descriptives et analysées en employant le test de t. P < 0,05 était considéré statistiquement significatif. Résultats: 2.310 de malades au total étaient examinés alors que 31 malades étaient identifiés échographiquement avec l'urolithiasis. La prévalence de l'urolithiasis était 13,4/1.000. L'âge médian était 31,12 ± 3,69 ans. Il y avait 58,06% du sexe masculin et 41,93% du sexe féminin donnant la proportion du sexe féminin-au-sexe féminin de 1,3:1. L'apogée de l'âge d'incidence était 21 ­ 50 ans. La majorité (22 [71%]) se trouvait aux voies urinaires supérieures alors que 9 (27%) était aux voies urinaires inférieures. Les signes d'appel les plus communs étaient les douleurs renales remarquées en 12 (40%) de malades, suivis de hématurie en 4 (13,3%) des malades. Conclusion: La prévalence d'urolithiasis était 13,4/1.000. On peut servir de ces renseignements dans l'avenir dans la formulation des plans de santé pour la prévention de l'urolithiasis dans les hôpitaux des environs.

Low-Dose CT for Evaluation of Suspected Urolithiasis: Diagnostic Yield for Assessment of Alternative Diagnoses.

OBJECTIVE: The purpose of this study is to assess the diagnostic yield of low-dose (LD) CT for alternative diagnoses in patients with suspected urolithiasis. MATERIALS AND METHODS: In this retrospective study, we included 776 consecutive patients who underwent unenhanced abdominal CT for evaluation of suspected urolithiasis. All examinations were performed with an LD CT protocol; images were reconstructed using iterative reconstruction. The leading LD CT diagnosis was recorded for each patient and compared with the final clinical diagnosis, which served as the reference standard. RESULTS: The mean (± SD) effective dose of CT was 1.9 ± 0.6 mSv. The frequency of urolithiasis was 82.5% (640/776). LD CT reached a sensitivity of 94.1% (602/640), a specificity of 100.0% (136/136), and an accuracy of 95.1% (738/776) for the detection of urolithiasis. In 93 of 136 patients (68.4%) without urolithiasis, alternative diagnoses were established as the final clinical diagnoses. Alternative diagnoses were most commonly located in the genitourinary (n = 53) and gastrointestinal (n = 18) tracts. LD CT correctly provided alternative diagnoses for 57 patients (61.3%) and was false-negative for five patients (5.4%). The most common clinical alternative diagnoses were urinary tract infections (n = 22). Seven diagnoses missed at LD CT were located outside the FOV. For 43 of all 776 patients (5.5%), neither LD CT nor clinical workup could establish a final diagnosis. The sensitivity, specificity, and accuracy of LD CT for the detection of alternative diagnoses were 91.9% (57/62), 95.6% (43/45), and 93.5% (100/107), respectively. CONCLUSION: LD CT enables the diagnosis of most alternative diagnoses in the setting of suspected urolithiasis. The most frequent alternative diagnoses missed by LD CT are urinary tract infections or diagnoses located outside the FOV of the abdominopelvic CT scan.

Radiation dose reduction for CT assessment of urolithiasis using iterative reconstruction: A prospective intra-individual study.

OBJECTIVE: To assess the performance of hybrid (HIR) and model-based iterative reconstruction (MIR) in patients with urolithiasis at reduced-dose computed tomography (CT). METHODS: Twenty patients scheduled for unenhanced abdominal CT for follow-up of urolithiasis were prospectively included. Routine dose acquisition was followed by three low-dose acquisitions at 40%, 60% and 80% reduced doses. All images were reconstructed with filtered back projection (FBP), HIR and MIR. Urolithiasis detection rates, gall bladder, appendix and rectosigmoid evaluation and overall subjective image quality were evaluated by two observers. RESULTS: 74 stones were present in 17 patients. Half the stones were not detected on FBP at the lowest dose level, but this improved with MIR to a sensitivity of 100%. HIR resulted in a slight decrease in sensitivity at the lowest dose to 72%, but outperformed FBP. Evaluation of other structures with HIR at 40% and with MIR at 60% dose reductions was comparable to FBP at routine dose, but 80% dose reduction resulted in non-evaluable images. CONCLUSIONS: CT radiation dose for urolithiasis detection can be safely reduced by 40 (HIR)-60 (MIR) % without affecting assessment of urolithiasis, possible extra-urinary tract pathology or overall image quality. KEY POINTS: • Iterative reconstruction can be used to substantially lower the radiation dose. • This allows for radiation reduction without affecting sensitivity of stone detection. • Possible extra-urinary tract pathology evaluation is feasible at 40-60% reduced dose.

Routine deferred computed tomography for patients with suspected urolithiasis is low-value healthcare.

OBJECTIVE: The aim of this study was to investigate the benefits of deferred routine computed tomography of the kidneys, ureters and bladder (CT KUB) for patients with a self-limiting episode of suspected urolithiasis. MATERIALS AND METHODS: The study comprised a case series of consecutive patients examined with deferred routine CT KUB for control of suspected urolithiasis. Patients examined with CT KUB at the University Hospital of North Norway, between 1 January 2010 and 31 December 2013, were included. The final analysis included 189 CT KUBs (response rate 48%). All data were extracted from the patient case files. The primary endpoint was the proportion of asymptomatic patients with a confirmed diagnosis of urolithiasis on CT KUB that led to surgical intervention within 1 year from the initial CT scan. RESULTS: At the time of CT KUB, 171 patients (90%) were asymptomatic, of whom three (1.8%) were treated. Urolithiasis was confirmed on CT KUB in 23% of asymptomatic patients. CONCLUSION: Deferred CT KUB did not alter the clinical outcome for the great majority of asymptomatic patients. The majority of patients who received adequate pain relief in primary care remained asymptomatic, and did not need specialized healthcare. Refraining from CT KUB involves little risk. Deferred CT KUB for patients with suspected urolithiasis is a low-value healthcare service.

Bayesian comparative assessment of diagnostic accuracy of low-dose CT scan and ultrasonography in the diagnosis of urolithiasis after the application of the STONE score.

OBJECTIVE: The objective of our study was to assess the diagnostic quality of low-dose computed tomography (CT) when compared to ultrasound (US) in diagnosis of urolithiasis using STONE score as a predictor of pre-test probability and the Bayesian statistical model to calculate post-test probabilities (POST) for both diagnostic tests. METHODS: STONE score was used to form risk groups to obtain pre-test probabilities. Likelihood ratios (LR) were calculated from external data for low-dose CT and US. POST were obtained using pre-test probabilities and likelihood ratios with Bayesian nomogram. Absolute (ADG) and relative (RDG) gains in diagnostic value were calculated. RESULTS: Calculated +LR for US was 12 and -LR was 0.32; for CT, +LR was 19 and -LR 0.04. +LR and low STONE for US yielded POST 57% and RDG 470%; intermediate STONE POST 92% and RDG 84%; and high STONE POST 99% and RDG 10%. -LR and low STONE for US POST 3% and RDG -70%; intermediate POST 24% and RDG -52%; and high STONE POST 74% and RDG -17.7%. +LR and low STONE for CT POST 68% and RDG 580%; moderate STONE POST 95% and RDG 90%; and high STONE POST 99% and RDG 10%. -LR and low STONE for CT POST 0% and RDG -100%; intermediate POST 4% and RDG -92%; and high STONE POST 26% and RDG -71.1%. ANOVA calculations comparing CT vs US for +LR showed no statistical significance (P value = 0.9893; LR- P value = 0.5488). CONCLUSION: Bayesian statistical analysis demonstrated slight superiority of CT scan over US on STONE score low- and moderate-risk stratified subtypes, whereas no significant advantage was seen when evaluating high-probability patients.

Urolithiasis and Frequent CT Scans: Does Chronic Pain Play a Role?

INTRODUCTION: Urolithiasis is among the top 10 causes of Emergency Department (ED) visits in the United States. Approximately 50% of these patients undergo abdominopelvic CT scan, many more than once. We hypothesized that chronic pain conditions may contribute to frequent CT scans in patients who are evaluated in ED for urolithiasis. METHODS: A retrospective review of patients presenting to our tertiary care and the associated satellite EDs for urolithiasis, during the period 12/2012-05/2013, was performed. Patients with multiple ED visits and two or more abdominopelvic CT scans in any 6-month period were labeled as the frequent CT group. Control group consisted of similar patients who had no more than one CT scan in any 6-month period. Background information, number of CT scans for urolithiasis and other reasons, and the presence of chronic pain (established pain clinic visits, chronic pain medication, known chronic pain syndromes) were captured from charts. Wilcoxon rank-sum test and Fisher's exact test were used to compare variables. Multivariable logistic regression was performed to identify predictors associated with frequent CT scans. RESULTS: We identified 185 patients with frequent CTs and 139 patients in the control arm. Frequent CT scans were independently associated with chronic pain (odds ratio [OR]: 2.67, confidence interval [95% CI]: 1.55, 4.50), age (OR: 0.73, 95% CI: 0.60, 0.89), history of prior urolithiasis (OR: 2.15, 95% CI: 1.11, 4.15), and Medicaid insurance status (OR: 3.94, 95% CI: 1.66, 9.35). CONCLUSION: Chronic pain is a significant contributing factor to frequent CT scans among patients presenting to ED with urolithiasis, leading to increased radiation exposure and healthcare costs.

Is the Economic Impact and Utilization of Imaging Studies for Pediatric Urolithiasis Across the United States Increasing?

OBJECTIVE: To identify longitudinal trends of economic impact and resource utilization for management of pediatric urolithiasis using national databases. METHODS: We analyzed the 2006-2012 Nationwide Emergency Department Sample and Nationwide Inpatient Sample. We used ICD-9 (International Classification of Diseases) codes to identify patients (≤18 years) diagnosed with urolithiasis. Diagnostic imaging and surgeries were identified using ICD-9 and Current Procedural Technology codes. We abstracted demographic, imaging, procedure, and charge data. Weighted descriptive statistics were calculated to describe the population's demographics and economic expenditures by clinical setting and year. RESULTS: In total, 45,333 inpatient admissions (68% females) and 234,559 emergency department encounters (63% females) were identified. Most patients (84%) were teenagers and the southern region of the United States was the most common geographic region for all encounters (44%). There was no significant trend in number of urolithiasis encounters over the period studied. Utilization of all imaging techniques increased; in particular, computed tomography was used in 23% of encounters in 2006 and 40% in 2012 (P < .0001). The mean charge per emergency department visit increased by 60% from $3645 in 2006 to $5827 in 2012 (P < .0001). The mean charge increased for inpatient admissions by 102%, from $16,399 in 2006 to $33,205 in 2012 (P < .0001). Total charges increased 72% over the study period from $230 million in 2006 to $395 million in 2012 (P < .0001), outpacing medical inflation over the same period. CONCLUSION: Charges for pediatric urolithiasis management increased by 65% from 2006 to 2012 despite stable frequency of patient encounters. The utilization of computerized tomography in pediatric urolithiasis increased as well.

Assessment of 1 mSv urinary tract stone CT with model-based iterative reconstruction.

OBJECTIVE: The purpose of this study was to evaluate stone detection, assessment of secondary signs of stone disease, and diagnostic confidence utilizing submillisievert CT with model-based iterative reconstruction (MBIR) in a North American population with diverse body habitus. MATERIALS AND METHODS: Fifty-two adults underwent stone CT using a split-dose protocol; weight-based projected volume CT dose index (CTDIvol) and dose-length product (DLP) were divided into two separate acquisitions at 80% and 20% dose levels. Images were reconstructed with MBIR. Five blinded readers counted stones in three size categories and rated "overall diagnostic confidence" and "detectability of secondary signs of stone disease" on a 0-4 scale at both dose levels. Effective dose (ED) in mSv was calculated as DLP multiplied by conversion coefficient, k, equal to 0.017. RESULTS: Mean ED (80%, 3.90±1.44 mSv; vs 20%, 0.97±0.34 mSv [p<0.001]) and number of stones detected (80%, 193.6±25.0; vs 20%, 154.4±15.4 [p=0.03]) were higher in scans at 80% dose level. Intrareader correlation between scans at 80% and 20% dose levels was excellent (0.83-0.97). With 80% scans as reference standard, mean sensitivity and specificity at 20% varied with stone size (<3 mm, 74% and 77%; ≥3 mm, 92% and 82%). The 20% scans scored lower than 80% scans in diagnostic confidence (2.46±0.50; vs 3.21±0.36 [p<0.005]) and detectability of secondary signs (2.41±0.39; vs 3.19±0.29 [p<0.005]). CONCLUSION: Aggressively dose-reduced (~1 mSv) MBIR scans detected most urinary tract stones of 3 mm or larger but underperformed the low-dose reference standard (3-4 mSv) scans in small (<3 mm) stone detection and diagnostic confidence.

The S.T.O.N.E. Score: a new assessment tool to predict stone free rates in ureteroscopy from pre-operative radiological features.

OBJECTIVE: To develop a user friendly system (S.T.O.N.E. Score) to quantify and describe stone characteristics provided by computed axial tomography scan to predict ureteroscopy outcomes and to evaluate the characteristics that are thought to affect stone free rates. MATERIALS AND METHODS: The S.T.O.N.E. score consists of 5 stone characteristics: (S) ize, (T)opography (location of stone), (O)bstruction, (N)umber of stones present, and (E)valuation of Hounsfield Units. Each component is scored on a 1-3 point scale. The S.T.O.N.E. Score was applied to 200 rigid and flexible ureteroscopies performed at our institution. A logistic model was applied to evaluate our data for stone free rates (SFR). RESULTS: SFR were found to be correlated to S.T.O.N.E. Score. As S.T.O.N.E. Score increased, the SFR decreased with a logical regression trend (p < 0.001). The logistic model found was SFR=1/(1+e^(-z)), where z=7.02-0.57•Score with an area under the curve of 0.764. A S.T.O.N.E. Score ≤ 9 points obtains stone free rates > 90% and typically falls off by 10% per point thereafter. CONCLUSIONS: The S.T.O.N.E. Score is a novel assessment tool to predict SFR in patients who require URS for the surgical therapy of ureteral and renal stone disease. The features of S.T.O.N.E. are relevant in predicting SFR with URS. Size, location, and degree of hydronephrosis were statistically significant factors in multivariate analysis. The S.T.O.N.E. Score establishes the framework for future analysis of the treatment of urolithiasis.

Assessment of renal shape of horseshoe kidney with multidetector row CT in adult patients: relationship between urolithiasis and renal isthmus.

OBJECTIVE: The aim of this study was to evaluate the relationship between urolithiasis and characteristics of renal shape in adult patients with horseshoe kidney (HSK) diagnosed on multidetector row computed tomography (MDCT). METHODS: We evaluated 36 patients with HSK and urolithiasis (Group A) and 70 patients with HSK without urolithiasis (Group B) whose disease was diagnosed on non-contrast MDCT. Two radiologists measured minimum width of the renal isthmus and maximum length of the renal pelvis and evaluated coexisting neoplastic diseases on axial computed tomographic (CT) images with 5-mm reconstruction, and we compared those measurements between the Groups A and B. RESULTS: The overall mean maximum length of the renal pelvis, 12.7±9.2 mm, did not differ significantly between the 2 groups. Minimum isthmus width was larger in patients with HSK and urolithiasis (11.0±5.6 mm), than those without urolithiasis (9.5±5.1 mm). No patient in either groups had a urological renal tumor. CONCLUSIONS: Patients of HSK might have tendency of a high incidence of stone formation. Because urolithiasis is a risk factor for tumors of the renal pelvis, monitoring of patients with HSK requires careful attention to isthmus width on CT images.

[Modern diagnostic assessment of the upper urinary tract using multislice CT urography]. / Moderne Diagnostik des oberen Harntraktes mittels Mehrschicht-CT-Urographie.

The advent of Multislice Computed Tomography (MSCT) has made evaluation of the entire urinary tract with high-resolution sections during a single breath-hold a reality. Acquisition of multiple thin overlapping slices provides excellent two-dimensional (2D) and three-dimensional (3D) reformations of the urinary tract. The concept of "Multislice CT Urography (MSCTU)" has emerged from this technical improvement. As a result, a wide range of pathologies inside and outside the urinary tract can be identified. During the last several years, MSCTU has challenged intravenous urography (IVU) in the evaluation of urinary tract abnormalities. Compared with IVU, MSCT(U) is more sensitive and specific in the detection and characterization of a variety of urinary tract disorders, including renal masses and urolithiasis. The main advantage of IVU has been its ability to offer excellent delineation of pelvicalyceal and ureteral anatomy and to depict subtle uroepithelial abnormalities. MSCTU has already shown promising results for overcoming this challenge. Optimal opacification and distension appear to be an essential requirement for a thorough evaluation of the collecting system. Dedicated preparation strategies have been developed to meet these technical difficulties. The biggest disadvantage of MSCTU is the significant radiation exposure. For broad routine clinical application, there is still a need for dose reduction protocols despite the ongoing technical developments in MSCTU. In this article, we outline the different concepts of technical processing for MSCTU and summarize the current role of MSCTU in the evaluation of the upper urinary tract.