Determining Variable Costs in the Acute Urolithiasis Cycle of Care Through Time-Driven Activity-Based Costing.

OBJECTIVE: To characterize full cycle of care costs for managing an acute ureteral stone using time-driven activity-based costing. METHODS: We defined all phases of care for patients presenting with an acute ureteral stone and built an overarching process map. Maps for sub-processes were constructed through interviews with providers and direct observation of clinical spaces. This facilitated calculation of cost per minute for all aspects of care delivery, which were multiplied by associated process times. These were added to consumable costs to determine cost for each specific step and later aggregated to determine total cost for each sub-process. We compared costs of eight common clinical pathways for acute stone management, defining total cycle of care cost as the sum of all sub-processes that comprised each pathway. RESULTS: Cost per sub-process included $920 for emergency department (ED) care, $1665 for operative stent placement, $2368 for percutaneous nephrostomy tube placement, $106 for urology clinic consultation, $238 for preoperative center visit, $4057 for ureteroscopy with laser lithotripsy (URS), $2923 for extracorporeal shock wave lithotripsy, $169 for clinic stent removal, $197 for abdominal x-ray, and $166 for ultrasound. The lowest cost pathway ($1388) was for medical expulsive therapy, whereas the most expensive pathway ($8002) entailed a repeat ED visit prompting temporizing stent placement and interval URS. CONCLUSION: We found a high degree of cost variation between care pathways common to management of acute ureteral stone episodes. Reliable cost accounting data and an understanding of variability in clinical pathway costs can inform value-based care redesign as payors move away from pure fee-for-service reimbursement.

Patients' poor performance status is an independent risk factor for urosepsis induced by kidney and ureteral stones.

This study was aimed to identify the risk factors for urosepsis caused by kidney and ureteral stones. One hundred and nine patients who had kidney or ureteral stones and who were treated with trans-ureteral lithotripsy (TUL) at our institution from 2016 to 2020 were included. We investigated the risk factors for urosepsis caused by kidney or ureteral stones that occurred prior to TUL. Thirty patients (28%) had urosepsis prior to TUL. Patients were divided into a urosepsis group (n = 30, 28%) and a non-urosepsis group (n = 79, 72%). Patients' characteristics (gender, age, performance status [PS] score, presence of diabetes mellitus, and skeletal muscle mass), as well as their stone and urine characteristics (stone size, presence of obstructive ureteral stones, stone composition, and urine and stone cultures), were compared between the two groups. When compared to the non-urosepsis group, patients with urosepsis were more likely to be older (p < 0.001), female (p < 0.001), with lower skeletal muscle mass (p < 0.001) and with poor PSs (p < 0.001). For stone and urine characteristics, infection stones (p = 0.01), positive urine (p < 0.001) and stone culture (p = 0.007) were more often detected in patients with urosepsis. A multivariate analysis showed patients' poor PS to be an independent risk factor for urosepsis due to kidney and ureteral stones (OR = 15.7; 95% CI = 2.2-115, p = 0.007). Our study revealed that the most significant risk factor for urosepsis caused by kidney and ureteral stones was the patients' poor PS.

A prospective, matched comparison of ultra-low and standard-dose computed tomography for assessment of renal colic.

OBJECTIVE: To determine the diagnostic accuracy of ultra-low-dose computed tomography (ULDCT) compared with standard-dose CT (SDCT) in the evaluation of patients with clinically suspected renal colic, in addition to secondary features (hydroureteronephrosis, perinephric stranding) and additional pathological entities (renal masses). PATIENTS AND METHODS: A prospective, comparative cohort study was conducted amongst patients presenting to the emergency department with signs and symptoms suggestive of renal or ureteric colic. Patients underwent both SDCT and ULDCT. Single-blinded review of the image sets was performed independently by three board-certified radiologists. RESULTS: Among 21 patients, the effective radiation dose was lower for ULDCT [mean (SD) 1.02 (0.16) mSv] than SDCT [mean (SD) 4.97 (2.02) mSv]. Renal and/or ureteric calculi were detected in 57.1% (12/21) of patients. There were no significant differences in calculus detection and size estimation between ULDCT and SDCT. A higher concordance was observed for ureteric calculi (75%) than renal calculi (38%), mostly due to greater detection of calculi of <3 mm by SDCT. Clinically significant calculi (≥3 mm) were detected by ULDCT with high specificity (97.6%) and sensitivity (100%) compared to overall detection (specificity 91.2%, sensitivity 58.8%). ULDCT and SDCT were highly concordant for detection of secondary features, while ULDCT detected less renal cysts of <2 cm. Inter-observer agreement for the ureteric calculi detection was 93.9% for SDCT and 87.8% for ULDCT. CONCLUSION: ULDCT performed similarly to SDCT for calculus detection and size estimation with reduced radiation exposure. Based on this and other studies, ULDCT should be considered as the first-line modality for evaluation of renal colic in routine practice.

Ureteroscopy is more cost effective than shock wave lithotripsy for stone treatment: systematic review and meta-analysis.

INTRODUCTION: A rising incidence of kidney stone disease has led to an increase in ureteroscopy (URS) and shock wave lithotripsy (SWL). Our aim was to compare the cost of URS and SWL for treatment of stones. METHODS: A systematic review and meta-analysis based on Cochrane and PRISMA standards was conducted for all studies reporting on comparative cost of treatment between URS and SWL. The cost calculation was based on factual data presented in the individual studies as reported by the authors. English language articles from January 2001 to December 2017 using Medline, PubMed, EMBASE, CINAHL, Cochrane library and Google Scholar were selected. Our study was registered with PROSPERO (International prospective register of systematic reviews)-registration number CRD 42017080350. RESULTS: A total of 12 studies involving 2012 patients (SWL-1243, URS-769) were included after initial identification and screening of 725 studies with further assessment of 27 papers. The mean stone size was 10 and 11 mm for SWL and URS, respectively, with stone location in the proximal ureter (n = 8 studies), distal ureter (n = 1), all locations in the ureter (n = 1) and in the kidney (n = 2). Stone free rates (84 vs. 60%) were favourable for URS compared to SWL (p < 0.001). Complication rates (23 vs. 30%) were non-significantly in favor of SWL (p = 0.11) whereas re-treatment rates (11 vs. 27%) were non-significantly in favor of URS (p = 0.29). Mean overall cost was significantly lower for URS ($2801) compared to SWL ($3627) (p = 0.03). The included studies had high risk of bias overall. On sub-analysis, URS was significantly cost-effective for both stones < 10 and ≥ 10 mm and for proximal ureteric stones. CONCLUSION: There is limited evidence to suggest that URS is less expensive than SWL. However, due to lack of standardization, studies seem to be contradictory and further randomized studies are needed to address this issue.

Radiological noninvasive assessment of ureteral stone impaction into the ureteric wall: A critical evaluation with objective radiological parameters.

PURPOSE: To determine the predictive value of certain radiological parameters for an objective asssessment of the presence of ureteral stone impaction. MATERIALS AND METHODS: Seventy-nine patients with a single proximal ureteral stones were retrieved from the departmental database. Both clinical and particularly radiological data of all cases were well evaluated on this aspect. In addition to the time period between the first colic attack and definitive management; diameter of proximal ureter and renal pelvis, longitudinal and transverse stone size, Hounsfied unit (HU) of the stone and lastly ureteral wall thickness at the impacted stone site were all carefully evaluated and noted. RESULTS: Patients had a single proximal ureteral stone. While mean age of the cases was ranged 20 to 78 years; mean stone size was 15.62±4.26 mm. Evaluation of our data demonstrated that although there was a statistically significant correlation between ureteral wall thickness and patients age, transverse diameter of the stone, ureteral diameter just proximal to the stone, renal pelvic diameter and the duration of renal colic attacks; no correlation could be demonstrated between patients sex and the HU of the stone. CONCLUSIONS: Prediction of the presence and degree of proximal ureteral stone impaction is a challenging issue and our data indicated a highly significant correlation between ureteral wall thickness and the some certain radiological as well as clinical parameters evaluated which will give an objective information about the presence of impaction which may in turn be helpful in the follow-up and also management plans of such calculi.

Use of medical expulsive therapy in children: An assessment of nationwide practice patterns and outcomes.

INTRODUCTION: Early data support the use of medical expulsive therapy (MET) in children. However, little is known regarding use or outcomes associated with MET outside of pediatric-specific practices. Using a national administrative dataset, we sought to characterize utilization patterns of MET as well as assess outcomes associated with MET exposure. STUDY DESIGN: We interrogated the MarketScan Commercial Claims and Encounters database to identify children under the age of 18 presenting to the emergency department (ED) with any diagnosis of upper urinary tract calculi (UUTC, including renal and ureteral calculi). MET exposure was defined as having a prescription filled for a MET agent within 1 week of the ED encounter. Characteristics of children receiving MET were defined and outcomes compared between children with and without MET exposure. RESULTS: Of 1325 children included in the study, 13.2% received MET, including 15.4% of children with a diagnosis of "calculus of the ureter." MET use increased significantly throughout the study period (p = 0.004), although only 30.4% of children considered potential MET candidates received MET in the final year of the study (2013). Among all patients, receipt of MET was associated with male gender, presence of comorbidity, provider-type (urologist), and year of diagnosis, although among those with a specific diagnosis of "calculus of the ureter," only year of diagnosis remained a significant factor. Rates of unplanned physician visits and surgical interventions were similar between groups. Children receiving MET were more likely to receive follow-up imaging, although only 46% of children with ureteral calculi had appropriate follow-up imaging within 90 days, regardless of MET exposure. Odds ratios of factors and outcomes associated with MET exposure are shown in the Table. DISCUSSION: Although early data support safety and efficacy MET in children, nationwide use in children is low among potential candidates for MET. For children with ureteral calculi, only year of diagnosis was a significant factor associated with MET use. No difference in unplanned physician visits or surgical interventions was noted. Most notable, however, was the low rate of follow-up imaging within 90 days for children presenting acutely with UUTC. CONCLUSIONS: Use of MET for children with ureteral calculi is increasing, although still fewer than a third of children considered potential candidates receive this treatment. Follow-up imaging is not obtained for many children with ureteral calculi. Future work is needed to standardize management and follow-up protocols for children with acute renal colic.

Evaluation with Decision Trees of Efficacy and Safety of Semirigid Ureteroscopy in the Treatment of Proximal Ureteral Calculi.

PURPOSE: The decision on the choice of proximal ureteral stone therapy depends on many factors, and sometimes urologists have difficulty in choosing the treatment option. This study is aimed at evaluating the factors affecting the success of semirigid ureterorenoscopy (URS) using the "decision tree" method. MATERIALS AND METHODS: From January 2005 to November 2015, the data of consecutive patients treated for proximal ureteral stone were retrospectively analyzed. A total of 920 patients with proximal ureteral stone treated with semirigid URS were included in the study. All statistically significant attributes were tested using the decision tree method. RESULTS: The model created using decision tree had a sensitivity of 0.993 and an accuracy of 0.857. While URS treatment was successful in 752 patients (81.7%), it was unsuccessful in 168 patients (18.3%). According to the decision tree method, the most important factor affecting the success of URS is whether the stone is impacted to the ureteral wall. The second most important factor affecting treatment was intramural stricture requiring dilatation if the stone is impacted, and the size of the stone if not impacted. CONCLUSIONS: Our study suggests that the impacted stone, intramural stricture requiring dilatation and stone size may have a significant effect on the success rate of semirigid URS for proximal ureteral stone. Further studies with population-based and longitudinal design should be conducted to confirm this finding.

Evaluation of low-dose dual energy computed tomography for in vivo assessment of renal/ureteric calculus composition.

PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. RESULTS: A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p<0.001). The DE ratio could confidently differentiate uric acid, struvite, calcium oxalate, and carbonate apatite calculi (p<0.001) with cutoff values of 1.12, 1.34, and 1.66, respectively, giving >80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.

Assessment of ureterovesical jet dynamics in obstructed ureter by urinary stone with color Doppler and duplex Doppler examinations.

This study was designed to evaluate ureterovesical jet dynamics in obstructed ureter and to compare it with those of contralateral unobstructed side. Forty-six patients with diagnosis of ureteral stone, based on imaging findings in computed tomography were enrolled in this study. The gray-scale ultrasound exam from both kidneys and urinary bladder was performed. Then, ureterovesical jet characteristics including ureteral jet frequency, duration and peak velocity were assessed by color Doppler and duplex Doppler studies in both obstructed and unobstructed ureters by a radiologist, 15-30 min after oral hydration with 750-1,000 mL of water. When compared with contralateral normal side, the ureterovesical jet in obstructed ureter showed less frequency (0.59 vs. 3.04 jets/min; P < 0.05), shorter duration (1.24 vs. 5.26 s; P < 0.05) and lower peak velocity (5.41 vs. 32.09 cm/s; P < 0.05). The cut-off points of 1.5 jets/min, 2.5 s and 19.5 cm/s for difference of ureteral jet frequency, duration and peak velocity between obstructed and contralateral normal ureters yielded sensitivities of 97.8, 95.6 and 100 % and specificities of 87, 87.9 and 97.8 %, respectively for diagnosis of ureteral obstruction. Given the safety of Doppler study and significant differences in flow dynamics of obstructed versus unobstructed ureters, our findings demonstrated the utility of Doppler ultrasound examination as a useful adjunct to gray-scale ultrasound by improving the accuracy of ultrasound exam in diagnosis of ureteral obstruction.

Three-dimensional assessment of urinary stone on non-contrast helical computed tomography as the predictor of stonestreet formation after extracorporeal shock wave lithotripsy for stones smaller than 20 mm.

The incidence of stonestreet formation after extracorporeal shock wave lithotripsy (ESWL) rises with increasing stone burden. However, stonestreet after ESWL is often experienced even in stones smaller than 20 mm. To examine whether the non-contrast helical computed tomography (CT) data could predict stonestreet formation in these stones, 53 radiopaque stones of 5-20 mm treated with ESWL were evaluated. Maximal dimension was measured on plain radiograph. From an attenuation value histogram graphed from the CT data, total stone volume and mean attenuation value were calculated. Seven stonestreets longer than 25 mm developed. There was no significant difference in maximal dimension and total stone volume between stones that did and stones that did not develop stonestreet. Mean attenuation value was the sole significant predictive factor. Application of mean attenuation value with cut-off level of 650 HU would anticipate stonestreet formation with a sensitivity of 85.7% and a specificity of 71.7%. The estimated risk of stonestreet formation is high in the treatment of stones with higher mean attenuation value.

Low-dose and standard-dose unenhanced helical computed tomography for the assessment of acute renal colic: prospective comparative study.

PURPOSE: To compare the efficacy of low-dose and standard-dose computed tomography (CT) for the diagnosis of ureteral stones. MATERIAL AND METHODS: Unenhanced helical CT was performed with both a standard dose (260 mAs, pitch 1.5) and a low dose (50 mAs, pitch 1.5) in 121 patients suspected of having acute renal colic. The two studies were prospectively and independently interpreted for the presence and location of ureteral stones, abnormalities unrelated to stone disease, identification of secondary signs, i.e. hydronephrosis and perinephric stranding, and tissue rim sign. The standard-dose CT images were interpreted by one reviewer and the low-dose CT images independently by two reviewers unaware of the standard-dose CT findings. The findings of the standard and low-dose CT scans were compared with the exact McNemar test. Interobserver agreements were assessed with kappa analysis. The effective radiation doses resulting from two different protocols were calculated by means of commercially available software to which the Monte-Carlo phantom model was given. RESULTS: The sensitivity, specificity, and accuracy of standard-dose CT for detecting ureteral stones were 99%, 93%, and 98%, respectively, whereas for the two reviewers the sensitivity of low-dose CT was 93% and 95%, specificity 86%, and accuracy 92% and 94%. We found no significant differences between standard-dose and low-dose CT in the sensitivity and specificity for diagnosing ureter stones (P >0.05 for both). However, the sensitivity of low-dose CT for detection of 19 stones less than or equal to 2 mm in diameter was 79% and 68%, respectively, for the two reviewers. Low-dose CT was comparable to standard-dose CT in visualizing hydronephrosis and the tissue rim sign. Perinephric stranding was far less clear on low-dose CT. Low-dose CT had the same diagnostic performance as standard-dose CT in diagnosing alternative diseases. Interobserver agreement between the two low-dose CT reviewers in the diagnosis of ureter stones and alternative diseases, the identification of secondary signs, and tissue rim sign were high, with kappa values ranging from 0.769 to 0.968. On standard-dose CT scans, the calculated mean effective radiation dose was 7.30 mSv for males and 10.00 mSv for females. On low-dose CT scans, the calculated mean effective radiation dose was 1.40 mSv for males and 1.97 mSv for females. CONCLUSION: Compared with standard scans using 260 mAs, low-dose unenhanced helical CT using a reduced tube current of 50 mAs results in a concomitant decrease in the radiation dose of 81%. Although low-dose CT was limited in its ability to depict small-sized calculi less than or equal to 2 mm, it is still comparable to standard-dose CT for the diagnosis of ureter stones and alternative disease.

Transvaginal sonography in the assessment of distal ureteral calculi.

OBJECTIVES: To explore the morphological and functional findings of transvaginal sonography (TVS) in the diagnosis and management of distal ureteral calculi. METHODS: We retrospectively reviewed the imaging studies in seven cases of distal ureteral calculi (study group) and 20 cases of female volunteers without urinary tract infection (control group). All 27 patients had undergone TVS for assessment of the lower urinary tract. The variables measured on ultrasound included the presence or absence of distal ureteral calculi, the size and location of a calculus if present, the presence or absence of the ureter jet phenomenon, morphological changes of the ureteral papilla and adjoining tissue, and the height of the ureteral papilla, as well as vascular changes seen on Doppler imaging. RESULTS: In the controls, 80% of the ureteral papillae were triangular and 20% trapezoidal. The average (+/-SD) height of the ureteral papillae was 3.5 +/- 0.7 mm on the right and 3.6 +/- 0.9 mm on the left. There was no statistically significant difference between the heights of the right and left papillae (P = 0.619). In the study group, echogenic stones were identified in all seven patients and a hypoechogenic tubular structure connected to the involved papilla was identified in 6/7 patients. The average height of the involved papilla was 6.7 +/- 1.6 mm. Ureteric jets were visible in all patients in both the study and control groups. CONCLUSION: In patients with distal ureteral calculi, TVS provides a rapid, non-invasive and repeatable means of assessing the morphology and function of the distal ureter.

Contrast enhanced spiral computerized tomography in patients with chronic obstructive uropathy and normal serum creatinine: a single session for anatomical and functional assessment.

PURPOSE: We evaluated contrast enhanced spiral computerized tomography (CT) as a single session for the anatomical and functional assessment of patients with chronic obstructive uropathy and normal serum creatinine. MATERIALS AND METHODS: The study included 65 patients with unilateral or bilateral chronic renal obstruction and normal serum creatinine. Five patients had bilateral obstruction and the remaining 60 had unilateral obstruction and a normal contralateral kidney. Therefore, the total number of renal units was 130, that is 70 obstructed and 60 normal. All patients underwent contrast enhanced spiral CT together with excretory urography (IVP) and Tc-mercaptoacetyltriglycine renal scan. CT was used to identify the cause of obstruction and selectively determine the glomerular filtration rate (GFR) of the 2 kidneys. The diagnostic accuracy of CT for identifying the cause of hydronephrosis was compared with that of IVP. Moreover, a correlation was made between CT GFR and isotope GFR. RESULTS: Obstruction was caused by ureteropelvic junction narrowing in 25 cases, ureteral stones in 21, ureteral stricture in 20 and extrinsic ureteral obstruction in 4. Contrast enhanced spiral CT identified the cause of hydronephrosis in all obstructed kidneys (100% sensitivity), while IVP identified the cause in 52 (74% sensitivity), which was a significant difference (p <0.05). CT and IVP excluded obstruction in all normal kidneys (100% specificity). A comparison between the isotope GFR of obstructed kidneys with the corresponding CT GFR showed a perfect correlation (r = 0.78, p <0.0001). Moreover, a similar comparison between isotope GFR and CT GFR of normal kidneys showed an excellent correlation (r = 0.73, p <0.0001). In obstructed and normal kidneys mean isotope clearance was not significantly different from that of mean CT clearance. CONCLUSIONS: Contrast enhanced spiral CT is more sensitive than IVP for identifying the cause of chronic obstructive uropathy. Moreover, it is as accurate as radioisotope renal scan for calculating the total and separate kidney function. We recommend spiral CT with contrast medium as a single radiological diagnostic modality for the assessment of patients with chronic renal obstruction and normal serum creatinine.

Acute ureterolithiasis: incidence of secondary signs on unenhanced helical CT and influence on patient management.

AIM: The purpose of this study was to determine the incidence of secondary signs associated with ureteral stones on unenhanced helical computed tomography (CT) of patients with acute renal colic, and to correlate these with patient management and outcome. MATERIALS AND METHODS: One hundred and ten patients with ureterolithiasis were evaluated prospectively for the secondary signs of obstruction on unenhanced helical CT. Our attention was focused primarily on the presence or absence of seven secondary signs on unenhanced helical CT, including hydronephrosis, unilateral renal enlargement, perinephric oedema, unilateral absence of the white pyramid, hydroureter, periureteral oedema and lateroconal fascial thickening. RESULTS: Of the 110 patients, 91 (82.7%) had hydroureter, 88 (80%) had hydronephrosis, 65 (59%) had periureteric oedema and 63 (57.2%) had unilateral renal enlargement. Ninety stones passed spontaneously and 21 required intervention. CONCLUSION: Secondary signs of urinary tract obstruction are useful and supportive findings in interpretation of the CT examination. In our experience, the most reliable signs indicating ureteral obstruction are hydroureter, hydronephrosis, periureteral oedema and unilateral renal enlargement, respectively. In addition, stones larger than 6 mm, located within the proximal two thirds of the ureter, and seen associated with five or more the secondary signs of obstruction, are more likely to require endoscopic removal and/or lithotripsy.

Unenhanced helical computed tomography vs intravenous urography in patients with acute flank pain: accuracy and economic impact in a randomized prospective trial.

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted alternative to intravenous urography (IVU) in patients with acute flank pain and suspected ureterolithiasis. The purpose of our randomized prospective study was to analyse the diagnostic accuracy of UHCT vs IVU in the normal clinical setting with special interest on economic impact, applied radiation dose and time savings in patient management. A total of 122 consecutive patients with acute flank pain suggestive of urolithiasis were randomized for UHCT ( n=59) or IVU ( n=63). Patient management (time, contrast media), costs and radiation dose were analysed. The films were independently interpreted by four radiologists, unaware of previous findings, clinical history and clinical outcome. Alternative diagnoses if present were assessed. Direct costs of UHCT and IVU are nearly identical (310/309 Euro). Indirect costs are much lower for UHCT because it saves examination time and when performed immediately initial abdominal plain film (KUB) and sonography are not necessary. Time delay between access to the emergency room and start of the imaging procedure was 32 h 7 min for UHCT and 36 h 55 min for IVU. The UHCT took an average in-room time of 23 min vs 1 h 21 min for IVU. Mild to moderate adverse reactions for contrast material were seen in 3 (5%) patients. The UHCT was safe, as no contrast material was needed. The mean applied radiation dose was 3.3 mSv for IVU and 6.5 mSv for UHCT. Alternative diagnoses were identified in 4 (7%) UHCT patients and 3 (5%) IVU patients. Sensitivity and specificity of UHCT and IVU was 94.1 and 94.2%, and 85.2 and 90.4%, respectively. In patients with suspected renal colic KUB and US may be the least expensive and most easily accessable modalities; however, if needed and available, UHCT can be considered a better alternative than IVU because it has a higher diagnostic accuracy and a better economic impact since it is more effective, faster, less expensive and less risky than IVU. In addition, it also has the capability of detecting various additional renal and extrarenal pathologies.

Assessment of the clinical utility of the rim and comet-tail signs in differentiating ureteral stones from phleboliths.

OBJECTIVE: This study was designed to assess interobserver variability in identifying the rim and comet-tail signs and to determine the clinical utility of these signs in determining whether or not the calcifications with which they are associated represent ureteral calculi. MATERIALS AND METHODS: Two radiologists and a radiology resident, unaware of the final diagnosis, reviewed preselected helical CT images from renal stone examinations in patients with 65 indeterminate pelvic calcifications. Assessment of calcifications for rim or comet-tail signs was performed independently of an assessment for the following five secondary signs of urinary tract obstruction: caliectasis, pelviectasis, ureterectasis, perinephric stranding, and renal enlargement. Agreement in identifying rim and comet-tail signs was assessed by obtaining kappa statistics. The utility the of rim or comet-tail signs in determining whether ureterolithiasis was present in patients in whom perinephric stranding and ureterectasis were present or absent was determined. The frequency with which one or more of each of the five assessed secondary signs was identified ipsilateral to a calcification having rim or comet-tail signs was also tabulated. RESULTS: Kappa values for interobserver agreement ranged from 0.49 to 0.73. In only one patient was a rim sign detected in the absence of ureterectasis and perinephric stranding. Reviewers identified at least three of the five assessed secondary signs ipsilateral to calcifications showing a rim sign in all but one patient (by each radiologist) and four patients (by the resident). When three or more secondary signs of obstruction were seen ipsilateral to a calcification having a comet-tail sign, in all but one instance, this was because the calcification was a ureteral calculus or because there was a separate ipsilateral ureteral calculus. CONCLUSION: In many instances, observers did not agree about whether the rim and comet-tail signs were present. The rim sign was observed in the absence of any secondary signs of urinary tract obstruction in only one (1.5%) of the 65 patients in our series (95% confidence interval, 0-5.3%). The comet-tail sign, when accompanied by secondary signs of obstruction, should indicate that an ipsilateral ureteral stone is present and not the reverse.

Ultrasound vs CT for the detection of ureteric stones in patients with renal colic.

The aim of our study was to compare the accuracy of non-contrast spiral CT with ultrasound (US) for the diagnosis of ureteral calculi in the evaluation of patients with acute flank pain. 62 consecutive patients with flank pain were examined with both CT and US over a period of 9 months. All patients were prospectively defined as either positive or negative for ureterolithiasis, based on follow-up evaluation. 43 of the 62 patients were confirmed as having ureteral calculi based on stone recovery or urological interventions. US showed 93% sensitivity and 95% specificity in the diagnosis of ureterolithiasis; CT showed 91% and 95%, respectively. Pathology unrelated to urinary stone disease was demonstrated in six patients. Although both modalities were excellent for detecting ureteral stones, consideration of cost and radiation lead us to suggest that US be employed first and CT be reserved for when US is unavailable or non-diagnostic.

Randomized prospective comparison of non-contrast enhanced helical computed tomography and intravenous urography in the diagnosis of acute ureteric colic.

Non-contrast enhanced helical CT has become an accepted technique for evaluating acute ureteric colic. The results of a randomized prospective comparison of the accuracy, cost and radiation dose of CT and intravenous urography (IVU) are presented. All patients presenting to the Emergency Department with symptoms and signs suggestive of ureteric colic over a 16-month period (n = 242) were randomized to CT or IVU. Follow up was obtained for 228 patients (94%), with 14 patients (6%) lost to follow up. One hundred and twenty-three patients (54%) underwent CT and 105 (46%) had an IVU. At follow up the sensitivity and specificity of CT were each 100%, while those of IVU were 99% and 100%, respectively. Computed tomography demonstrated seven of 26 (27%) potential alternative diagnoses, whereas IVU suggested one of 23 (4%). Estimates of the average effective dose were calculated for CT (4.95 mSv) and IVU (1.48 mSv, 95% confidence interval (CI) 0.7-2.27). Radiation dose and intravenous contrast material safety are discussed and the relative costs are considered. Computed tomography is as accurate as IVU in the diagnosis of acute ureteric colic. It confers certain major diagnostic benefits, and is a fast, well-tolerated technique. Its accompanying higher effective radiation dose is recognized.

Bayesian regression methodology for estimating a receiver operating characteristic curve with two radiologic applications: prostate biopsy and spiral CT of ureteral stones.

RATIONALE AND OBJECTIVES: The authors evaluated two Bayesian regression models for receiver operating characteristic (ROC) curve analysis of continuous diagnostic outcome data with covariates. MATERIALS AND METHODS: Full and partial Bayesian regression models were applied to data from two studies (n = 180 and 100, respectively): (a) The diagnostic value of prostate-specific antigen (PSA) levels (outcome variable) for predicting disease after radical prostatectomy (gold standard) was evaluated for three risk groups (covariates) based on Gleason scores. (b) Spiral computed tomography was performed on patients with proved obstructing ureteral stones. The predictive value of stone size (outcome) was evaluated along with two treatment options (gold standard), as well as stone location (in or not in the ureterovesical junction [UVJ]) and patient age (covariates). Summary ROC measures were reported, and various prior distributions of the regression coefficients were investigated. RESULTS: (a) In the PSA example, the ROC areas under the full model were 0.667, 0.769, and 0.703, respectively, for the low-, intermediate-, and high-risk groups. Under the partial model, the area beneath the ROC curve was 0.706. (b) The ROC areas for patients with ureteral stones in the UVJ decreased dramatically with age but otherwise were close to that under the partial model (ie, 0.774). The prior distribution had greater influence in the second example. CONCLUSION: The diagnostic tests were accurate in both examples. PSA levels were most accurate for staging prostate cancer among intermediate-risk patients. Stone size was predictive of treatment option for all patients other than those 40 years or older and with a stone in the UVJ.