Evaluation of differential renal function in children - a comparative study between magnetic resonance urography and dynamic renal scintigraphy.

BACKGROUND: Urinary system anomalies, both congenital and acquired, constitute a relatively common clinical problem in children. The main role of diagnostic imaging is to determine early diagnosis and support therapeutic decisions to prevent the development of chronic renal disease. The aim of this study was to evaluate the utility of magnetic resonance urography (MRU) in assessment of urinary system in children, by comparing differential renal function calculated using MRU with dynamic renal scintigraphy (DRS). MATERIALS AND METHODS: The study group consisted of 46 patients aged 1 week to 17 years (median 7 (0.5; 13) years, 17 (37%) girls, 29 (63%) boys), who underwent dynamic renal scintigraphy due to various clinical reasons. All participants underwent MRU, which was used to measure differential renal function. Functional analysis was performed using dedicated external software (CHOP-fMRU and pMRI without prior knowledge of DRS results. MRU results acquired using pMRI were assessed for inter and intraobserver agreement. RESULTS: Statistical analysis of the results showed excellent agreement between MRU and DRS in measuring differential renal function with Pearson correlation coefficient 0.987 for CHOP-fMRU and 0.971 for pMRI, p < 0.001. Interclass correlation coefficient (ICC) for these programs was 0.987 (95% CI 0.976-0.993) and 0.969 (95% CI 0.945-0.983) respectively, p < 0.001. The Bland-Altman 95% limits of agreement for CHOP-fMRU results vs. DRS was - 6.29-5.50 p.p. and for pMRI results vs. DRS - 9.15-9.63 p.p. The differential renal function measurements calculated in pMRI showed excellent intraobserver and interobserver agreement with ICC 0.996 (95% CI 0.994-0.998) and 0.992 (95% CI 0.986-0.996) respectively, p < 0.001. CONCLUSIONS: The study showed no significant differences between magnetic resonance urography and dynamic renal scintigraphy in calculating differential renal function. It indicates high utility of MRU in the evaluation of urinary system in children.

Quantitative differentiation of non-invasive bladder urothelial carcinoma and inverted papilloma based on CT urography.

PURPOSE: To investigate the value of CT urography (CTU) indicators in the quantitative differential diagnosis of bladder urothelial carcinoma (BUC) and inverted papilloma of the bladder (IPB). MATERIAL AND METHODS: The clinical and preoperative CTU imaging data of continuous 103 patients with histologically confirmed BUC or IPB were retrospectively analyzed. The imaging data included 6 qualitative indicators and 7 quantitative measures. The recorded clinical information and imaging features were subjected to univariate and multivariate logistic regression analysis to find independent risk factors for BUC, and a combined multi-indicator prediction model was constructed, and the prediction model was visualized using nomogram. ROC curve analysis was used to calculate and compare the predictive efficacy of independent risk factors and nomogram. RESULTS: Junction smoothness, maximum longitudinal diameter, tumor-wall interface and arterial reinforcement rate were independent risk factors for distinguishing BUC from IPB. The AUC of the combined model was 0.934 (sensitivity = 0.808, specificity = 0.920, accuracy = 0.835), and its diagnostic efficiency was higher than that of junction smoothness (AUC=0.667, sensitivity = 0.654, specificity = 0.680, accuracy = 0.660), maximum longitudinal diameter (AUC=0.757, sensitivity = 0.833, specificity = 0.604, accuracy = 0.786), tumor-wall interface (AUC=0.888, sensitivity = 0.755, specificity = 0.808, accuracy = 0.816) and Arterial reinforcement rate (AUC=0.786, sensitivity = 0.936, specificity = 0.640, accuracy = 0.864). CONCLUSION: Above qualitative and quantitative indicators based on CTU and the combination of them may be helpful to the differential diagnosis of BUC and IPB, thus better assisting in clinical decision-making. KEY POINTS: 1. Bladder urothelial carcinoma (BUC) and inverted papilloma of the bladder (IPB) exhibit similar clinical symptoms and imaging presentations. 2. The diagnostic value of CT urography (CTU) in distinguishing between BUC and IPB has not been documented. 3. BUC and IPB differ in lesion size, growth pattern and blood supply. 4. The diagnostic efficiency is optimized by integrating multiple independent risk factors into the prediction model.

Low-dose versus conventional CT urography using dual-source CT with different time-current product values and the same tube voltage: image quality and diagnostic performance in various diagnoses.

OBJECTIVES: To compare the image quality and diagnostic performance of low-dose CT urography to that of concurrently acquired conventional CT using dual-source CT. METHODS: This retrospective study included 357 consecutive CT urograms performed by third-generation dual-source CT in a single institution between April 2020 and August 2021. Two-phase CT images (unenhanced phase, excretory phase with split bolus) were obtained with two different tube current-time products (280 mAs for the conventional-dose protocol and 70 mAs for the low-dose protocol) and the same tube voltage (90 kVp) for the two X-ray tubes. Iterative reconstruction was applied for both protocols. Two radiologists independently performed quantitative and qualitative image quality analysis and made diagnoses. The correlation between the noise level or the effective radiation dose and the patients' body weight was evaluated. RESULTS: Significantly higher noise levels resulting in a significantly lower liver signal-to-noise ratio and contrast-to-noise ratio were noted in low-dose images compared to conventional images (P < .001). Qualitative analysis by both radiologists showed significantly lower image quality in low-dose CT than in conventional CT images (P < .001). Patient's body weight was positively correlated with noise and effective radiation dose (P < .001). Diagnostic performance for various diseases, including urolithiasis, inflammation, and mass, was not different between the two protocols. CONCLUSIONS: Despite inferior image quality, low-dose CT urography with 70 mAs and 90 kVp and iterative reconstruction demonstrated diagnostic performance equivalent to that of conventional CT for identifying various diseases of the urinary tract. ADVANCES IN KNOWLEDGE: Low-dose CT (25% radiation dose) with low tube current demonstrated diagnostic performance comparable to that of conventional CT for a variety of urinary tract diseases.

Estimation of renal function using iodine maps in dual-energy spectral computed tomography urography: a feasibility and accuracy study.

PURPOSE: To explore the feasibility of measuring glomerular filtration rate (GFR) using iodine maps in dual-energy spectral computed tomography urography (DEsCTU) and correlate them with the estimated GFR (eGFR) based on the equation of creatinine-cystatin C. MATERIALS AND METHODS: One hundred and twenty-eight patients referred for DEsCTU were retrospectively enrolled. The DEsCTU protocol included non-contrast, nephrographic, and excretory phase imaging. The CT-derived GFR was calculated using the above 3-phase iodine maps (CT-GFRiodine) and 120 kVp-like images (CT-GFR120kvp) separately. CT-GFRiodine and CT-GFR120kvp were compared with eGFR using paired t-test, correlation analysis, and Bland-Altman plots. The receiver operating characteristic curves were used to test the renal function diagnostic performance with CT-GFR120kvp and CT-GFRiodine. RESULTS: The difference between eGFR (89.91 ± 18.45 ml·min-1·1.73 m-2) as reference standard and CT-GFRiodine (90.06 ± 20.89 ml·min-1·1.73 m-2) was not statistically significant, showing excellent correlation (r = 0.88, P < 0.001) and agreement (± 19.75 ml·min-1·1.73 m-2, P = 0.866). The correlation between eGFR and CT-GFR120kvp (66.13 ± 19.18 ml·min-1·1.73 m-2) was poor (r = 0.36, P < 0.001), and the agreement was poor (± 40.65 ml·min-1·1.73 m-2, P < 0.001). There were 62 patients with normal renal function and 66 patients with decreased renal function based on eGFR. The CT-GFRiodine had the largest area under the curve (AUC) for distinguishing between normal and decreased renal function (AUC = 0.951). CONCLUSION: The GFR can be calculated accurately using iodine maps in DEsCTU. DEsCTU could be a non-invasive and reliable one-stop-shop imaging technique for evaluating both the urinary tract morphology and renal function.

Discrepant guidelines in the evaluation of hematuria.

PURPOSE: To assess discrepancies in current imaging recommendations for hematuria among North American societies: American College of Radiology (ACR), American Urological Association (AUA), and Canadian Urological Association (CUA). METHODS: The latest available ACR Appropriateness Recommendations, AUA guidelines, and CUA guidelines were reviewed. AUA and CUA guidelines imaging recommendations by variants and level of appropriateness were converted to match the style of ACR. Imaging recommendations including modality, anatomy, and requirement for contrast were recorded. RESULTS: Clinical variants included microhematuria without risk factors, microhematuria with risk factors, gross hematuria, and microhematuria during pregnancy. CUA recommends ultrasound kidneys as the first-line imaging study in the first 3 variants; pregnancy is not explicitly addressed. For hematuria without risk factors, ACR does not routinely recommend imaging, while AUA recommends shared decision-making to decide repeat urinalysis versus cystoscopy with ultrasound kidneys. For hematuria with risk factors and gross hematuria, ACR recommends CT urography; MR urography can also be considered in gross hematuria. AUA further stratifies intermediate- and high-risk patients, for which ultrasound kidneys and CT urography are recommended, respectively. For pregnancy, ACR and AUA both recommend ultrasound kidneys, though AUA additionally recommends consideration of CT or MR urography after delivery. CONCLUSION: There is no universally agreed upon algorithm for diagnostic evaluation. Discrepancies centered on the role of upper tract imaging with ultrasound versus CT. Prospective studies and/or repeat simulation studies that apply newly updated guidelines are needed to further clarify the role of imaging, particularly for patients with microhematuria with no and intermediate risk factors.

Feasibility and Implementation of a 4D Free-Breathing Variable Density Stack-of-Stars Functional Magnetic Resonance Urography in Young Children Without Sedation.

BACKGROUND: Functional magnetic resonance urography (MRU) is well established in the diagnostic workup of urinary tract anomalies in children, providing comprehensive morphological and functional information. However, dynamic contrast-enhanced images acquired in the standard Cartesian k-space manner are prone to motion artifacts. A newly introduced 4D high spatiotemporal resolution dynamic contrast-enhanced magnetic resonance imaging based on variable density elliptical centric radial stack-of-stars sharing technique has shown improved image quality regarding motions under free breathing. OBJECTIVE: The aims of this study were to implement this 4D free-breathing sequence for functional MRU and to compare its image quality and analyzability with standard breath-hold Cartesian MRU. MATERIALS AND METHODS: We retrospectively evaluated all functional 4D MRU performed without general anesthesia between September 2021 and December 2022 and compared them with matched pairs (age, affected kidney, diagnosis) of standard Cartesian MRU between 2016 and 2022. Image analysis was performed by 2 radiologists independently regarding the following criteria using a 4-point Likert scale, with 4 being the best: overall image quality, diagnostic confidence, respiratory motion artifacts, as well as sharpness and contrast of aorta, kidneys, and ureters. We also measured vertical kidney motion due to respiratory motion and compared the variance for each kidney using F test. Finally, both radiologists calculated the volume, split renal volume (vDRF), split renal Patlak function (pDRF), and split renal function considering the volume and Patlak function (vpDRF) for each kidney. Values were compared using Bland-Altman plots and F test. RESULTS: Forty children (20 for 4D free-breathing and standard breath-hold, respectively) were enrolled. Ten children of each group were examined using feed-and-sleep technique (median age: 4D, 3.3 months; standard, 4.2 months), 10 were awake (median age: 4D, 8.9 years; standard, 8.6 years). Overall image quality, diagnostic confidence, respiratory motion artifacts, as well as sharpness and contrast of the aorta, kidneys, and ureters were rated significantly better for 4D free-breathing compared with standard breath-hold by both readers ( P ranging from <0.0001 to 0.005). Vertical kidney motion was significantly reduced in 4D free-breathing for the right and the left kidney (both P < 0.001). There was a significantly smaller variance concerning the differences between the 2 readers for vpDRF in 4D MRU ( P = 0.0003). In contrast, no significant difference could be demonstrated for volume ( P = 0.05), vDRF ( P = 0.93), and pDRF ( P = 0.14). CONCLUSIONS: We demonstrated the feasibility of applying a 4D free-breathing variable density stack-of-stars imaging for functional MRU in young pediatric patients with improved image quality, fewer motion artifacts, and improved functional analyzability.

Evaluation of image quality and radiation dose in computed tomography urography following tube voltage optimisation.

INTRODUCTION: Computed tomography urography (CTU) comprehensively evaluates the urinary tract. However, the procedure is associated with a high radiation dose due to multiple scan series and therefore requires optimisation. The study performed CTU protocol optimisation based on a reduction in tube voltage (kV) using quality assurance (QA) phantom and clinical images and evaluated image quality and radiation dose. METHODS: The study was prospectively conducted on patients referred for CTU. The patients were grouped into A and B and were scanned with the standard protocol, a protocol used for the routine CTU at the CT centre before optimisation, and optimised protocol, a protocol with reduced kV respectively. The protocols were first tried on a quality assurance (QA) phantom before being applied to patients, and image quality was assessed based on signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). In addition, the clinical images were assessed based on the visibility of the anatomical criteria for CT images by five observers with >5 years of experience. The data were analysed using both visual grading characteristic (VGC) curves and statistical package for social sciences (SPSS) version 22.0. RESULTS: The dose was significantly lower in the optimised protocol with a 10 % reduction in both volume computed tomography dose index and (CTDIvol) and dose length product (DLP) for the phantom images, and a 26 % reduction in CTDIvol and 28 % in DLP for the clinical images. However, there was no significant difference in image quality noted between the standard and optimised protocols based on the quantitative and qualitative image quality evaluation using both the QA phantom and clinical images. CONCLUSION: The findings revealed a significant dose reduction in the optimised protocol. Further, image quality in standard and optimised protocols did not differ significantly based on quantitative and qualitative methods. IMPLICATION FOR PRACTICE: kV optimisation in contrast-enhanced procedures provides dose reduction and should be encouraged in the medical imaging departments.

Essentials of Computed Tomography Imaging of Hematuria.

Hematuria is defined usually as the presence of blood in the urine, either on voiding or in a catheterized specimen. Hematuria is broadly divided into microscopic and gross hematuria and may be symptomatic or asymptomatic. The causes of hematuria include a very wide spectrum of conditions. However, here, we have filtered the causes causing gross hematuria, including calculus, trauma, tumors, vascular, and miscellaneous causes. Plain X-rays of the kidney, ureter, and bladder; ultrasound; intravenous urography; computed tomography (CT); magnetic resonance imaging; retrograde ureterography and pyelography (RGP); cystoscopy; and ureteroscopy are techniques that are useful for diagnosis. In the past, one or a combination of several techniques was used to evaluate hematuria but recently, advances in CT urography mean that it can be used alone for this task. This article briefly reviews the common causes of gross hematuria in adults and their evaluation by CT-based urography. Gross hematuria is evaluated well with CT scan urography which includes an unenhanced scan, the nephrographic phase, and the excretory phase. Unenhanced scans are routinely performed to evaluate the basic parameters such as the size, shape, position, and outline of the kidneys and calculus disease, which is the most common cause of hematuria. Renal parenchymal diseases including masses are best visualized in the nephrographic phase along with other abdominal organs. Delayed excretory phases including the kidneys, ureters, and bladder are useful for detecting urothelial diseases. CT urography's protocol permits evaluations of hematuria through a single examination.

Glomerular Filtration Rate Measured Based on Iomeprol Clearance Assessed at CT Urography in Living Kidney Donor Candidates.

Background Estimating glomerular filtration rate (GFR) from serum creatinine can be inaccurate, and current procedures for measuring GFR are time-consuming and cumbersome. Purpose To develop a method for measuring GFR based on iomeprol clearance assessed at CT urography in kidney donor candidates and compare this with iohexol clearance (reference standard for measuring GFR). Materials and Methods This cross-sectional retrospective study included data from kidney donor candidates who underwent both iohexol clearance and CT urography between July 2016 and October 2022. CT-measured GFR was calculated as the iomeprol excretion rate in the urinary system between arterial and excretory phases (Hounsfield units times milliliters per minute) divided by a surrogate for serum iomeprol concentration in the aorta at the midpoint (in Hounsfield units). Performance of CT-measured GFR was assessed with use of mean bias (mean difference between CT-measured GFR and iohexol clearance), precision (the distance between quartile 1 and quartile 3 of the bias [quartile 3 minus quartile 1], with a small value indicating high precision), and accuracy (percentage of CT-measured GFR values falling within 10%, 20%, and 30% of iohexol clearance values). Intraobserver agreement was assessed for 30 randomly selected individuals with the Lin concordance correlation coefficient. Results A total of 75 kidney donor candidates were included (mean age, 51 years ± 13 [SD]; 45 female). The CT-measured GFR was unbiased (1.1 mL/min/1.73 m2 [95% CI: -1.9, 4.1]) and highly precise (16.2 mL/min/1.73 m2 [quartiles 1 to 3, -6.6 to 9.6]). The accuracy of CT-measured GFR within 10%, 20%, and 30% was 61.3% (95% CI: 50.3, 72.4), 88.0% (95% CI: 80.7, 95.4), and 100%, respectively. Concordance between CT-based GFR measurements taken 2 months apart was almost perfect (correlation coefficient, 0.99 [95% CI: 0.98, 0.99]). Conclusion In living kidney donors, GFR measured based on iomeprol clearance assessed at CT urography showed good agreement with GFR measured based on iohexol clearance. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Davenport in this issue.

Application of contrast-enhanced ultrasound in the surgical treatment of vesicoureteral reflux in children.

BACKGROUND: To determine the utility of contrast-enhanced voiding urography (CeVUS) in the treatment of vesicoureteral reflux (VUR) through ureterovesical reimplantation in children. METHODS: A total of 159 children with recurrent urinary tract infections were selected for CeVUS and voiding cystourethrography (VCUG) from December 2018 to December 2020, among whom 78 patients were eventually diagnosed with VUR. Overall, 60 pyelo-ureteric units (PUUs) were operated according to surgical indications. Accordingly, we determined the general clinical characteristics of all children, obtained two-dimensional ultrasound images, assessed the reflux status of children using the contrast-enhanced technique, and compared the obtained results via CeVUS and VCUG. Both imaging modalities were reperformed at 6, 12, and 18 months after surgery to evaluate postoperative outcomes. In particular, we assessed the consistency of the evaluation and calculated the diagnostic efficacy of CeVUS for different levels of reflux at different time points. RESULTS: CeVUS showed considerable efficacy in the diagnosis of children with VUR. Notably, the diagnostic results of both CeVUS and VCUG achieved high agreement, with a kappa value of 0.966 (P < 0.001). The results of our follow-up at different stages and evaluation of postoperative efficacy revealed that CeVUS possessed substantial diagnostic efficacy and good consistency with VCUG. CONCLUSION: CeVUS is an accurate and safe examination, with considerable clinical significance for diagnosing VUR in children, determining the treatment approach, conducting follow-up during treatment, and evaluating subsequent treatment outcomes.

A rare case of right renal ectopia with ureteral triplication in a 37-year-old male: a case report.

Ureteral triplication is one of the least encountered congenital malformations of the upper urinary tract. We report a case of a 37-year-old male patient with right renal ectopia with triplication of the ureter which was diagnosed via computed tomography (CT) urography. This is an intriguing example because, as we discovered after reviewing the literature, the presentation is distinctive.

Evaluation of patients' post-operative results operated for hip fracture with computerized dynamic posturography: Proximal femoral nailing versus hip arthroplasty.

BACKGROUND: Proximal femoral nailing (PFN) and hip arthroplasty (HA) are the two most often utilized surgical procedures for treating hip fractures in older patients. The post-operative postural balance and functional outcomes of patients may be significantly influenced by the technical distinctions between PFN and HA. This will influence the surgeon's preferred course of therapy. To examine the functional outcomes of patients treated with PFN and HA following a hip fracture, this study used computerized dynamic posturography (CDP). The aim of that study was to evaluate how the two treatment modalities affected patients' post-operative balance, postural stability, and functional rehabilitation. METHODS: A total of 26 patients who underwent proximal femoral surgery (15 patients PFN [58%] and 11 patients HA [42%]) due to hip fractures were evaluated at least 12 months postoperatively. They were tested by direct radiographs, hip joint examinations, Harris hip score (HHS), and CDP. RESULTS: Twelve (46%) of 26 patients were male and 14 (54%) were female. The mean age of the participants in the study was 67.9±14.2 years. The mean follow-up period was 24 (12-44) months. The average Harris score of PFN group was 79.3 (46.8-100) points and HA group was 83.7 (61.9-99.9) points. There was no significant difference between the groups in terms of Harris Score (P=0.54). The average of the mixed value of the balance results obtained with CDP (the Composite score) for PFN group was 70.5 (56-79) points, and for HA group was 71.9 (56-83) points. There was no significant difference between the groups in terms of the Composite Score (P=0.47). Accordingly, 12 (80%) of the patients who underwent PFN had good results and 3 (20%) of them had bad results. Eight (72.7%) of those who underwent HA had good results and 3 (27.3%) had bad results. There was no statistically significant difference (P=0.66). CONCLUSION: Comparing the composite score for balance results and HHS results for rehabilitation with the data of the patients who underwent PFN and HA, there was no statistically significant difference between these two techniques in terms of postural stabil-ity and balance as a result of CDP examination.

Decreased percent change in renal pelvis diameter on diuretic functional magnetic resonance urography following administration of furosemide may help characterize unilateral uretero-pelvic junction obstruction.

BACKGROUND: A well-established definition of obstruction in the setting of congenital hydronephrosis is lacking. Multiple imaging modalities and radiographic characteristics or parameters have been described to help confirm the diagnosis of ureteropelvic junction obstruction (UPJO). We sought to evaluate the change in anterior-posterior renal pelvic diameter (APRPD) following furosemide administration in patients with unilateral hydronephrosis and confirmed UPJO on functional magnetic resonance urography (fMRU) who underwent pyeloplasty. MATERIALS AND METHODS: There were 49 patients who met inclusion criteria (11 females, 38 males; average age 2.2 years, SD 3.4 years) from February 2006 to September 2020, diagnosed with unilateral hydronephrosis (SFU Grade 3-4) who underwent fMRU prior to pyeloplasty for confirmed UPJO. 29 of the included patients also underwent a post-pyeloplasty fMRU. A weight-adjusted dose of 1 mg/kg of furosemide (max 20 mg/kg) was administered intravenously. Two board-certified pediatric radiologists measured the APRPD of the obstructed and non-dilated kidneys prior to pyeloplasty and APRPD of the hydronephrotic kidneys on the post-pyeloplasty follow up fMRUs. Measurements were performed on images prior to and approximately 30 min following furosemide injection. RESULTS: The average APRPD before furosemide injection in the obstructed kidney prior to pyeloplasty was 26.3 mm (SD 9.0 mm) compared to the non-dilated (not obstructed) kidney measurement of 5.1 mm (SD 3.6 mm) (p < 0.001). Following administration of furosemide, the average APRPD was 31.4 mm (SD 8.8 mm) in the obstructed kidney, and 7.8 mm (SD 4.1 mm) in the non-dilated kidney (p < 0.001). After pyeloplasty, the pre-furosemide APRPD measurement was 17.8 mm (SD 11 mm), which was significantly less compared to the pre-pyeloplasty APRPD (p < 0.001). The post-pyeloplasty, post-furosemide APRPD measurement was 25.8 mm (SD 12 mm), also significantly less compared to the pre-pyeloplasty measurement (p = 0.02). The changes in APRPD in the obstructed kidney prior to pyeloplasty was 5.1 mm (SD 3.5 mm) and after pyeloplasty was 8 mm (SD 4.6 mm) (p = 0.002). Change in APRPD in the non-dilated kidney was 2.7 mm (SD 2.3 mm). Percent APRPD change in the obstructed kidney was 22.9% (SD 18.5%), which was significantly less than 33.3% (SD 22.1%) in the post-pyeloplasty kidney (p = 0.028) and 82.8% (SD 87.9%) in the non-dilated kidney (p < 0.001). CONCLUSIONS: A relatively smaller change in APRPD on fMRU following administration of furosemide in the setting of UPJO may serve as another predictive characteristic of obstructed kidneys.

Detection and characterization of urinary stones using material-specific images derived from contrast-enhanced dual-energy CT urography.

OBJECTIVE: To determine the accuracy of material-specific images derived from contrast-enhanced dual-energy CT urography (DECTU) in detecting and measuring urinary stones in comparison with that of unenhanced images and its utility in calcified stone differentiation. METHODS: 105 patients with 202 urinary stones (121 had confirmed composition by infrared spectroscopy) underwent triphasic (unenhanced, portal venous (VP) and excretory phase (EP)) DECTU. Material-specific images were derived in VP and EP with calcium-water, calcium-iodine and CaOxalate_Dihydrate (COD)-Hydroxyapatite (HAP) as basis material pairs. Stone number and size were recorded on unenhanced images and VP and EP material-specific images, where stone densities were also measured. Material densities of calcified stones (pure calcium oxalate [pCaO, n = 34], mixed calcium oxalate [mCaO, n = 14], mixed carbonate phosphate [mCaP, n = 70]) were compared and thresholds for differentiating these stones were determined using receiver operating characteristic analysis. RESULTS: All 202 urinary stones were detected on the unenhanced, calcium (water) and calcium (iodine) images in VP. While the detection rate was significantly decreased to 58 and 64% using calcium (water) and calcium (iodine) images in EP, respectively (all p < 0.001). Stone sizes measured on calcium (iodine) images in VP was similar to that of unenhanced images (10.6 vs 10.7 mm, p > 0.05). Significant differences in material densities were found among pCaO, mCaO and mCaP on COD(HAP) images with AUC of 0.72-0.74 for differentiating these stones. CONCLUSION: Material-specific images in VP derived from DECTU allow reliably detecting and measuring urinary tract stones in comparison with unenhanced images and can identify calcified stones with moderate diagnostic performance to provide potential 33% dose reduction. ADVANCES IN KNOWLEDGE: Material-specific images, especially the calcium (iodine) images in VP allow for reliable detection of urinary stones.Stone size measurement should be performed on the calcium (iodine) images in VP.Material density measurements on COD-HAP (VP) material decomposition images can be used to differentiate among pure calcium oxalate, mixed calcium oxalate and mixed carbonate phosphate stones with AUC of 0.72-0.74.

A retrospective survey to establish institutional diagnostic reference levels for CT urography examinations based on clinical indications: preliminary results.

Objective. To establish institutional diagnostic reference levels (IDRLs) based on clinical indications (CIs) for three- and four-phase computed tomography urography (CTU).Methods. Volumetric computed tomography dose index (CTDIvol), dose-length product (DLP), patients' demographics, selected CIs like lithiasis, cancer, and other diseases, and protocols' parameters were retrospectively recorded for 198 CTUs conducted on a Toshiba Aquilion Prime 80 scanner. Patients were categorised based on CIs and number of phases. These groups' 75th percentiles of CTDIvoland DLP were proposed as IDRLs. The mean, median and IDRLs were compared with previously published values.Results. For the three-phase protocol, the CTDIvol(mGy) and DLP (mGy.cm) were 22.7/992 for the whole group, 23.4/992 for lithiasis, 22.8/1037 for cancer, and 21.2/981 for other diseases. The corresponding CTDIvol(mGy) and DLP (mGy.cm) values for the four-phase protocol were 28.6/1172, 30.6/1203, 27.3/1077, and 28.7/1252, respectively. A significant difference was found in CTDIvoland DLP between the two protocols, among the phases of three-phase (except cancer) and four-phase protocols (except DLP for other diseases), and in DLP between the second and third phases (except for cancer group). The results are comparable or lower than most studies published in the last decade.Conclusions. The CT technologist must be aware of the critical dose dependence on the scan length and the applied exposure parameters for each phase, according to the patient's clinical background and the corresponding imaging anatomy, which must have been properly targeted by the competent radiologist. When clinically feasible, restricting the number of phases to three instead of four could remarkably reduce the patient's radiation dose. CI-based IDRLs will serve as a baseline for comparison with CTU practice in other hospitals and could contribute to national DRL establishment. The awareness and knowledge of dose levels during CTU will prompt optimisation strategies in CT facilities.

Toward the Deimplementation of Computed Tomography Urogram for Patients With Low- to Intermediate-risk Microscopic Hematuria: A Mixed-method Study of Factors Influencing Continued Use.

INTRODUCTION: Citing high costs, limited diagnostic benefit, and ionizing radiation-associated risk from CT urogram, in 2020 the AUA revised its guidelines from recommending CT urogram for all patients with microscopic hematuria to a deintensified risk-stratified approach, including the deimplementation of low-value CT urogram (ie, not recommending CT urogram for patients with low- to intermediate-risk microscopic hematuria). Adherence to revised guidelines and reasons for continued low-value CT urogram are unknown. METHODS: With the overarching objective of improving guideline implementation, we used a mixed-method convergent explanatory design with electronic health record data for a retrospective cohort at a single academic tertiary medical center in the southeastern United States and semistructured interviews with urology and nonurology providers to describe determinants of low-value CT urogram following guideline revision. RESULTS: Of 391 patients with microscopic hematuria, 198 (51%) had a low-value CT urogram (136 [69%] pre-guideline revision, 62 [31%] postrevision). The odds of ordering a low-value CT urogram were lower after guideline revisions, but the change was not statistically significant (OR: 0.44, P = .08); odds were 1.89 higher (P = .06) among nonurology providers than urology providers, but the difference was not statistically significant. Provider interviews suggested low-value CT urogram related to nonurology providers' limited awareness of revised guidelines, the role of clinical judgment in microscopic hematuria evaluation, and professional and patient influences. CONCLUSIONS: Our findings suggest low-value CT urogram deimplementation may be improved with guidelines and implementation support directed at both urology and nonurology providers and algorithms to support guideline-concordant microscopic hematuria evaluation approaches. Future studies should test these strategies.

Direct mapping of kidney function by DCE-MRI urography using a tetrazinanone organic radical contrast agent.

Chronic kidney disease (CKD) and acute kidney injury (AKI) are ongoing global health burdens. Glomerular filtration rate (GFR) is the gold standard measure of kidney function, with clinical estimates providing a global assessment of kidney health without spatial information of kidney- or region-specific dysfunction. The addition of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) to the anatomical imaging already performed would yield a 'one-stop-shop' for renal assessment in cases of suspected AKI and CKD. Towards urography by DCE-MRI, we evaluated a class of nitrogen-centered organic radicals known as verdazyls, which are extremely stable even in highly reducing environments. A glucose-modified verdazyl, glucoverdazyl, provided contrast limited to kidney and bladder, affording functional kidney evaluation in mouse models of unilateral ureteral obstruction (UUO) and folic acid-induced nephropathy (FAN). Imaging outcomes correlated with histology and hematology assessing kidney dysfunction, and glucoverdazyl clearance rates were found to be a reliable surrogate measure of GFR.

Functional MR urography in children - update 2023. / Funktionelle MR-Urografie im Kindesalter ­ Update 2023.

BACKGROUND: Functional MR urography (fMRU) has developed into an innovative, radiation-free option for assessing parameters of kidney function in pediatric radiology. The importance of fMRU in comparison to the standardized established nuclear medicine procedure (99mTc-Mercapto-acetyltriglycerine, MAG3 scintigraphy) is shown using SWOT analysis. METHODS: To assess the current state of research, a selective literature search was carried out in PubMed. Taking into account the current scientific status, the examination technique, preparation, and evaluation of fMRU are presented. RESULTS: As a result of the comparison with MAG3, fMRU is suitable for certain indications and represents an optimal combination of morphological and functional representation of the kidneys and urinary tract, especially in the case of surgical consequences. CONCLUSION: fMRU has been successfully established as a diagnostic method for assessing the morphology and function of the kidneys in competition with MAG3 scintigraphy. KEY POINTS: · Functional MRU allows reliable statements on the morphology and function of the kidneys and urinary tract.. · The results of the functional assessment of fMRU are comparable to the results of MAG3 scintigraphy.. · The complex implementation and demanding evaluation limits the spread of fMRU as a complete alternative to MAG3 scintigraphy. fMRU is reserved for special indications.. · Functional MRU has prevailed over MAG3 scintigraphy for complex renal and urinary tract anomalies (CAKUT) that require surgical correction. An example is the clarification of dribbling in girls, which is usually based on an ectopic opening of a ureter in a double system.. CITATION FORMAT: · Kirsch H, Krüger P, John-Kroegel U et al. Functional MR urography in children - update 2023. Fortschr Röntgenstr 2023; 195: 1097 - 1105.

Computed Tomography Urography: State of the Art and Beyond.

Computed Tomography Urography (CTU) is a multiphase CT examination optimized for imaging kidneys, ureters, and bladder, complemented by post-contrast excretory phase imaging. Different protocols are available for contrast administration and image acquisition and timing, with different strengths and limits, mainly related to kidney enhancement, ureters distension and opacification, and radiation exposure. The availability of new reconstruction algorithms, such as iterative and deep-learning-based reconstruction has dramatically improved the image quality and reducing radiation exposure at the same time. Dual-Energy Computed Tomography also has an important role in this type of examination, with the possibility of renal stone characterization, the availability of synthetic unenhanced phases to reduce radiation dose, and the availability of iodine maps for a better interpretation of renal masses. We also describe the new artificial intelligence applications for CTU, focusing on radiomics to predict tumor grading and patients' outcome for a personalized therapeutic approach. In this narrative review, we provide a comprehensive overview of CTU from the traditional to the newest acquisition techniques and reconstruction algorithms, and the possibility of advanced imaging interpretation to provide an up-to-date guide for radiologists who want to better comprehend this technique.