Utility of F-15 diuretic MAG3 renography in assessment of paediatric hydronephrosis.

INTRODUCTION: Diuretic renography is crucial in evaluation of paediatric hydronephrosis. Furosemide is conventionally given 15-20 min after radiolabelled tracer (F+15/F+20 protocol), however this is equivocal in around 15% of patients. Giving furosemide 15 min prior to tracer (F-15 MAG3 protocol) has been suggested as an additional tool in the investigation of patients with suspected upper urinary tract obstruction. However, the role of this method in assessment and management of paediatric hydronephrosis is not widely reported. OBJECTIVE: To investigate utility of F-15 renograms in children with hydronephrosis being assessed for Pelvi-Ureteric Junction Obstruction (PUJO). STUDY DESIGN: Retrospective review of patients <16 years old undergoing F-15 MAG3 renogram between 2018 and 2021 in our tertiary paediatric surgical centre. Data collected included patient demographics, mode of presentation, investigations, management and outcomes. RESULTS: Eighteen patients were included. Median age at F-15 renogram was 7.3 years. Eleven patients presented with antenatal hydronephrosis, 5 with symptoms in childhood and 2 with incidental hydronephrosis on trauma imaging. Fourteen patients were symptomatic. Ten had a prior non-obstructed F+20 renogram but persisting symptoms suggestive of PUJO. Seven had previous equivocal F+20 renograms. One symptomatic patient directly underwent an F-15 renogram. A conclusive result was obtained in 16/18 (89%); 11 patients had obstructed curves and 5 non-obstructed. Two asymptomatic patients' scans were inconclusive. All symptomatic patients had conclusive scans. Of 11 patients with an obstructed F-15, 9 have undergone pyeloplasty to date. All have had post-operative resolution in symptoms and static or improved post-operative ultrasound. One patient with an inconclusive scan underwent pyeloplasty due to persisting hydronephrosis and parent preference. Three patients with non-obstructed F-15 renograms have been discharged. One symptomatic patient with a non-obstructive F-15 had a ureteric stent inserted due to persistent flank pain; 1 continues under surveillance. DISCUSSION: It is known that conventional F+20 MAG3 renograms can give equivocal results. Published experience suggests that F-15 renograms are conclusive in the majority of patients. Routine primary use is, however, discouraged as they can 'over diagnose' obstruction and limit the study of tracer transit under physiological flow rates. This study indicates that the F-15 renogram is a useful adjunct in the assessment of patients with symptoms suggestive of PUJO who have previously had an equivocal or a non-obstructed F+20 renogram. CONCLUSION: F-15 renogram was conclusive in 89% of patients. We recommend using F-15 renograms to aid surgical decision-making in children with equivocal F+20 renograms, especially in the presence of symptoms.

Noninvasive assessment of renal dynamics and pH in a unilateral ureter obstruction model using DCE MR-CEST urography.

PURPOSE: To assess the potential of DCE MR CEST urography for assessing renal function in mice with unilateral ureter obstruction (UUO) by simultaneous pH and renal uptake/clearance measurements following injection of iopamidol. METHODS: The right ureter of nine mice was obstructed via suture ligation. The animals were imaged at day 1, 2, and 3 post-obstruction on an 11.7T MRI scanner. Ninety-six sets of saturated CEST images at 4.3 and 5.5 ppm were collected. Renal pH values were obtained by calculating the signal ratio for these two frequencies and using a pH calibration curve. Renal time activity curves were measured as a percentage change in the post-injection CEST signal at 4.3 ppm relative to the average pre-injection signal. RESULTS: For the healthy mice, the time activity curves of both kidneys were nearly identical and displayed rapid excretion of contrast. For the UUO mice, the dynamic CEST curves for the obstructed kidneys displayed prolonged time to peak (TTP) values and delayed contrast excretion compared with the contralateral (CL) kidneys. Renal pH maps of the healthy animals showed similar acidic values for both kidneys (pH 6.65 ± 0.04 vs 6.67 ± 0.02), whereas in the obstructed kidneys there was a significant increase in pH values compared with the CL kidneys (pH 6.67 ± 0.08 vs 6.79 ± 0.11 in CL and UUO kidneys, respectively). CONCLUSION: Our findings indicate that DCE-MR-CEST urography can detect changes in renal uptake/excretion and pH homeostasis and distinguish between obstructed and unobstructed kidney as early as 1 day after UUO.

Assessment of Individual Renal Function Using 99mTc-MAG3 Renography.

BACKGROUND/AIM: This study performed 99mTc-MAG3 renal scintigraphy on rabbit kidneys and evaluated its ability to identify obstructive or non-obstructive kidneys. MATERIALS AND METHODS: Renal function was assessed during a four-week post-obstruction period by obtaining planar images of 99mTc-MAG3 activity following an ear vein injection. The individual renal function was evaluated by renal scintigraphy in conjunction with histopathological and morphological examinations. RESULTS: The renal perfusion of 99mTc-MAG3 in the right kidney with a ureteral obstruction decreased with time. The width, height, and cortical thickness of the obstructed right kidney were significantly larger than those of the left kidney. A histopathological examination four weeks after the ureteral obstruction revealed a typical pattern of urinary tract obstruction, including multiple tubules, enlargement of the interstitial area, and cytoplasmic vacuoles. CONCLUSION: 99mTc-MAG3 renal scintigraphy provides the kidney shape and size and can identify potential obstructive and non-obstructive kidneys in rabbits.

[Comparison of functional magnetic resonance urography and dynamic renal scintigraphy in the functional assessment of ureteropelvic junction obstruction in children].

PURPOSE: In order to determine the role and significance of functional magnetic resonance urography (fMRU) in the diagnosis of ureteropelvic junction obstruction (UPJO), a comparative analysis of the results of fMRU and dynamic renal scintigraphy (DRS) was carried out. MATERIALS AND METHODS: From January 2017 to December 2019, fMRU and diuretic DRS were performed in 36 patients (mean age 89+/-63 months). Boys - 26 (72.2%), girls - 10 (27.8%). Left-sided hydronephrosis was detected in 23 (63.9%) children, right-sided in 12 (33.3%) patients, and bilateral lesions in 1 (2.8%) patient (2 renal units (RU)). Antenatal hydronephrosis was detected in 9 (25%) patients, and postnatally in 27 (75%) patients. According to ultrasound data, grade II hydronephrosis occurred in 11 (29.8%) RU, grade III - in 21 RU (56.7%), and grade IV - in 5 RU (13.5%) according to the SFU classification. A diuretic test was performed in 26 patients. RESULTS: Median and quartiles of differential renal function (DRF) according to fMRU data on the affected side were 37% [29; 43], and according to DRS - 46% [40;49]. When performing fMRU, a positive diuretic test was detected in 20 patients, 5 patients - negative and 1 patient - doubtful, and according to the DRS data, 12 patients had a positive test, 10 patients - negative and 4 patients - doubtful. Differences in DRF between fMRU and DRS varied between 0.7-33%. The average value of differences in DRF on the affected side was 11.3+/-8.5%. When comparing the results of DRF on the affected side, a moderate correlation was found on the Cheddock scale (r=0.59, p<0.05) between fMRU and DRS data. In comparison of the DRF using the Wilcoxon test, statistically significant differences were revealed (p<0,05). SUMMARY: Our experience demonstrates the high potential of fMRU in terms of replacing the classical methods of diagnosis of UPJO in children, taking into account the high correlation coefficients between the results of fMRU and DRS. Standardization of the fMRU protocol will increase the diagnostic relevance of information and in the future will make fMRU the only necessary study to determine management tactics for patients with UPJO.

Non-invasive evaluation of obstruction after ureteroscopic stone removal: Role of renal resistive index assessment.

OBJECTIVES: The aim of this study is to evaluate prediction of postoperative ureteral obstruction needing ureteral stent insertion by evaluating the resistive index (RI) values and the grade of hydronephrosis. MATERIAL AND METHODS: A total of 66 adult patients undergoing stentless endoscopic ureteral stone treatment (URS) between January 2018 and January 2019 were included in this prospective study. Preoperative patient and stone characteristics were noted. All patients were evaluated with renal Doppler ultrasonography study to assess degree of hydronephrosis and RI values. A renal Doppler ultrasonography was repeated at postoperative 1st, 3rd and 7th days. Changes in both RI and hydronephrosis levels before and after the procedures were noted. On the postoperative 7th day, patients were divided into two groups including obstructive and non-obstructive cases according to RI values assessed where a RI value of 0.7 was accepted as the cut-off for obstruction. The preoperative and perioperative characteristics of both groups were evaluated in a comparative manner. RESULTS: The mean patient age was 43.6 ± 1.72 years. Significant improvements were noted in RI and grade of hydronephrosis after the operation. The grade of hydronephrosis and RI values were found to improve more significantly on postoperative 3rd day when compared to the postoperative 7th day (p < 0.01 and p < 0.01). A significant correlation was detected between the grade of hydronephrosis (>grade 2) and obstructive RI values (> 0.7) in each postoperative visits (p: 0.001). RI values (> 0.7) at postoperative seventh days were correlated with larger mean stone size, increased ureteral wall thickness, increased diameter of the ureter proximal to the stone, and longer duration of the operation. Preoperative high-grade hydronephrosis indicated obstructive RI values at postoperative seventh day (p = 0.001) Conclusion: Changes in RI values on Doppler sonography and the grade of hydronephrosis may be a guiding parameter in assessing postoperative ureteral obstruction.

Point-of-care ultrasound is an accurate, time-saving, and cost-effective modality for post-operative imaging after pyeloplasty.

BACKGROUND: Dismembered pyeloplasty is considered the gold standard treatment for ureteropelvic junction obstruction (UPJO). Although the frequency and timing of follow up imaging after pyeloplasty is variable, renal ultrasound (RUS) is commonly utilized. With minimal training, point-of-care ultrasound (POCUS) can be easily performed by a urologist during a post-operative visit. OBJECTIVE: Our hypothesis is that POCUS is an accurate, time-saving, and cost-effective alternative to a complete retroperitoneal ultrasound (CRUS) performed by the Radiology Department after pyeloplasty. STUDY DESIGN: The clinical records of all children who underwent pyeloplasty (by any method) over a 12 month period at our institution were retrospectively reviewed. The exact timing and method (POCUS vs. CRUS) of follow up imaging was surgeon-dependent. Statistical analysis was performed to compare the time and cost of POCUS vs. CRUS. The clinical course of each patient who had each type of imaging was assessed. RESULTS: A total 45 patients were included in this analysis. Over a mean follow up period of 29 months, a total of 73 CRUS and 67 POCUS were performed. Each CRUS on average added 2 h to each patient's healthcare encounter. Had the 73 CRUS been performed as POCUS instead, this would have corresponded to $83,751 less charges to payers. There was no difference in the rate of the detection of worsening, stable, or improved hydronephrosis (HN) between either modality (p > 0.05). The recommended follow up time for observed HN was no different between CRUS and POCUS (p > 0.05). Children with worsening HN on POCUS underwent functional studies without confirmatory CRUS. Interestingly, two patients had metachronous, contralateral UPJO discovered during post-operative imaging. These were both discovered by POCUS. Nineteen (42%) patients who had attended at least one post-operative visit were eventually loss to follow-up. This occurred exclusively in those who did not have worsening ultrasound (p < 0.01). There was no difference in the loss to follow-up after POCUS (8) or CRUS (12) (p > 0.05). CONCLUSIONS: POCUS performed by a urologist is an accurate assessment of HN after pyeloplasty with time and cost savings to compared to a CRUS performed by a radiologist. POCUS is not associated with any difference in rate of detection of worsening HN or rate of loss to follow up.

Assessment of renal fibrosis in a rat model of unilateral ureteral obstruction with diffusion kurtosis imaging: Comparison with α-SMA expression and 18F-FDG PET.

PURPOSE: To investigate the utility of diffusion kurtosis imaging (DKI) MRI for evaluation of renal fibrosis in rats with unilateral ureteral obstruction (UUO). METHODS: Twenty-five rats had UUO, and ten rats were subjected to sham operation as control. DKI was performed on a 3.0 T MRI scanner on days 1, 3, 5, and 7 after ligation. All rats then underwent 18F-FDG dynamic PET to evaluate unilateral renal function, followed by histological analysis to examine α-smooth muscle actin (α-SMA) expression. DKI metrics were assessed among the time points and between two sides, and compared with maximum standardized uptake value (SUVmax), serum levels of creatinine and urea, and fibrosis marker α-SMA. RESULTS: Mean kurtosis (MK) on day 7, axial kurtosis (Ka) on days 3 and 7, mean diffusivity (MD) on days 1, 3, 5, and 7, and fractional anisotropy (FA) on days 3, 5, and 7 of cortex and medulla between the UUO and contralateral sides were significantly different (all p < 0.05). Over the course of UUO progression, there were significant changes in Ka, MD and FA of medulla (all p < 0.05). FA of medulla was positively correlated with SUVmax (r = 0.641, p < 0.001), and MD of cortex was negatively correlated with urea (r = -0.534, p = 0.001). MD of cortex was negatively correlated with α-SMA on UUO sides (r = -0.710, p < 0.001). CONCLUSIONS: DKI shows the potential for noninvasive assessment of renal fibrosis and unilateral renal function induced by UUO.

Hydronephrosis severity score: an objective assessment of hydronephrosis severity in children-a preliminary report.

The main challenge in the management of antenatally diagnosed hydronephrosis and ureteropelvic junction obstruction (UPJO) is to differentiate the one that is likely to resolve from the pathological one. In this study, a new hydronephrosis severity score (HSS), combining ultrasonographic and renographic parameters, has been developed. Hydronephrosis severity score was analyzed with regard to its usefulness in assessing the severity of UPJO, postoperative resolution, and interobserver reliability. METHODS: Hydronephrosis severity score was devised with three parameters: differential renal function (DRF), drainage curve pattern, and ultrasonogram grade (Table 1). Hydronephrosis severity score ranges were divided as 0-4, mild; 5-8, moderate; and 9-12, severe and compared with clinical outcomes (resolution, persistence, or surgical intervention) by retrospective case record review of children with unilateral UPJO. Among those who underwent surgery, surgical outcomes were compared with changes in HSS at 6-month follow-up. Hydronephrosis severity score was computed by three observers, and interobserver variability was calculated. RESULTS: A total of 125 case records (male:female = 93:32; right:left = 44:81) were analyzed. Among the patients analyzed, none (0/59) with HSS 0-4 warranted surgery, whereas 1 of 35 patients with HSS 5-8 underwent surgery, and all (31/31) with HSS 9-12 underwent surgery (P = 0.001). Overall, hydronephrosis resolved in 65, persisted in 28, and required surgery in 32 patients. Mean (standard deviation) HSS was 2.1 (0.75) in whom it resolved, 6.2 (0.78) in whom it persisted, and 10.2 (0.79) in those who underwent surgery (analysis of variance P = 0.001). Among those who underwent surgery, a better recovery of HSS was noted in younger infants (aged 2-5 months) with higher pre-operative DRF. There was 94.4% median agreement between radiologists and the surgeon (kappa 0.851), indicating a very good interobserver agreement. DISCUSSION: Loss of DRF on progressive renograms remains the accepted criterion of significant UPJO although the lost function does not always recover after pyeloplasty. Newer scoring systems keep evolving to predict the need for surgery as well as assess resolution of UPJO, and the study's preliminary report suggests that HSS could turn out to be one such useful tool. In this study, those who deteriorated were the ones with HSS ≥9. One can use this as a criterion and decide on intervention before DRF deterioration. Hydronephrosis severity score could also be applied as an objective parameter for quantifying improvement/deterioration after surgery and comparing outcomes across centers. The drawbacks of the present study are its small size and the retrospective nature. Further prospective studies are required to validate the usefulness of HSS.

Intravoxel incoherent motion MRI-derived parameters and T2* relaxation time for noninvasive assessment of renal fibrosis: An experimental study in a rabbit model of unilateral ureter obstruction.

PURPOSE: To evaluate the association of apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM) MRI-derived parameters, and T2* relaxation time with histopathological changes observed during renal fibrogenesis in a rabbit model of unilateral ureter obstruction (UUO). METHODS: Twenty New Zealand White rabbits underwent baseline MRI followed by surgery (sham or UUO) and then follow-up MRI at postoperative day (POD) 0, 3, 7, and 14. Hematoxylin and eosin and Masson's trichrome staining was performed to evaluate cell density and area of fibrosis. Spearman rank correlation and Pearson correlation tests and one-way analysis of variance were used for statistical analyses. RESULTS: There was a continuous increase in the area of fibrosis and cell density: rho = 0.900 (95% confidence interval [CI] = 0.760, 0.960; p < 0.0001) and 0.904 (95% CI = 0.769, 0.962; p < 0.0001), respectively. There was a tendency for all MRI variables to decrease at POD 3 and partly recover at POD 7. ADC, D, f, and T2* relaxation time showed significant correlation with area of fibrosis and cell density (r = -0.5177 and -0.6962, -0.5395 and -0.7851, -0.7168 and -0.7902, and -0.6808 and -0.7212, respectively; p = 0.0052-0.0481) while D* did not (p = 0.1997 and 0.7853, respectively). CONCLUSIONS: ADC, IVIM MRI-derived parameters, and T2* relaxation time were significantly associated with the area of fibrosis and cell density during renal fibrogenesis in a rabbit model of UUO. After validation in future studies, MRI may have potential for noninvasive assessment modality of renal fibrosis.

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.

50% dextrose versus normal saline as distension media during cystoscopy for assessment of ureteric patency.

OBJECTIVE: To compare the visualization of ureteric jets when using 50% dextrose (D50) as opposed to normal saline (NS) as distension media during cystoscopy. STUDY DESIGN: Cross sectional study. METHODS: Two patients each had two cystoscopy videos recorded at the time of a ureteric jet; one using NS and the other using D50 resulting in two sets of paired videos (four videos). A fifth cystoscopy video was recorded, as a control, at a time when there was no ureteric-jet. Fifty participants including attending physicians, residents and medical students were recruited at an academic-affiliated community hospital. Participants were blinded to the medium used and viewed each of the five videos. Participants assessed each video for presence of a ureteric-jet, ease of interpretation, and compared the paired D50 and NS videos for clarity of ureteric-jets. MAIN OUTCOME MEASURES: Participant's assessment of clarity of the ureteric jets when D50 was used as compared to when NS was used in the paired videos. RESULTS: All 100 observations of the two D50 videos with jets identified the presence of a jet; for the NS videos, 96/100 observations identified a jet, 2/100 did not identify a jet and 2/100 were unsure. 48/50 observations of the video with no jet were correct, while 2/50 were unsure. Participants rated the ureteric-jets to be clearer in videos with D50 (86% vs 14%, P<0.001); and had difficulty interpreting cystoscopy videos with NS (62% vs 2%, OR: 80, 95% CI: 10.2-627.6). CONCLUSION: Participants preferred the clarity of the ureteric-jet when 50% dextrose was used as the distension medium during cystoscopy as compared to normal saline.

CT-based assessment of renal function impairment in patients with acute unilateral ureteral obstruction by urinary stones.

PURPOSE: The purpose of our study was to evaluate computed tomography (CT) imaging factors related to renal function impairment in patients with acute unilateral ureteral obstruction by urinary stones. MATERIALS AND METHODS: The study included 94 patients who had acute unilateral ureteral obstruction due to a urinary stone and a normal contralateral kidney. We retrospectively investigated the serum creatinine (SCr) levels immediately prior to CT examination and at least 1 week after treatment. CT examinations were performed using a CT urography protocol, including pre- and post-contrast images. The 67 patients with a SCr change of less than 0.3 mg/dL constituted group A. The other 27 patients with a SCr decrease of more than 0.3 mg/dL constituted group B. To evaluate factors related to renal function impairment, differences in CT imaging factors between the two groups, including the cortical and medullary density, renal and pelvic anteroposterior diameter, and perinephric fluid, were statistically analyzed. RESULTS: The SCr immediately prior to CT examination significantly differed between the two groups. The follow-up SCr after resolution did not significantly differ between the two groups. The difference in the mean cortical and medullary HU on the nephrographic phase between the obstructed kidney and normal kidney was higher in group B than in group A (27.1 ± 23.1 and 69.4 ± 59.1 vs. 5.7 ± 8.8 and 31.8 ± 34.8; p < 0.001 and p = 0.004, respectively). The cut-off point for the difference in the mean cortical HU on the nephrographic phase between the obstructed kidney and normal kidney for renal function impairment was 15 HU, as determined by a receiver operating characteristic curve analysis. CONCLUSIONS: Patients with significantly impaired renal function due to an acute unilateral ureteral obstruction may show a decreased nephrogram of the affected kidney and a significant difference in the HU on the nephrographic phase between the obstructed and normal kidney.

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.

Assessment of renal function in mice with unilateral ureteral obstruction using 99mTc-MAG3 dynamic scintigraphy.

BACKGROUND: Renal scintigraphy using 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) is widely used for the assessment of renal function in humans. However, the application of this method to animal models of renal disease is currently limited, especially in rodents. Here, we have applied 99mTc-MAG3 renal scintigraphy to a mouse model of unilateral ureteral obstruction (UUO) and evaluated its utility in studying obstructive renal disease. METHODS: UUO mice were generated by complete ligation of the left ureter. Sham-operated mice were used as a control. Renal function was investigated on days 0, 1, 3, and 6 post-surgery using dynamic planar imaging of 99mTc-MAG3 activity following retro-orbital injection. Time-activity curves (TACs) were produced for individual kidneys and renal function was assessed by 1) the slope of initial 99mTc-MAG3 uptake (SIU), which is related to renal perfusion; 2) peak activity; and 3) the time-to-peak (TTP). The parameters of tubular excretion were not evaluated in this study as 99mTc-MAG3 is not excreted from UUO kidneys. RESULTS: Compared to sham-operated mice, SIU was remarkably (>60%) reduced in UUO kidneys at day 1 post surgery and the TACs plateaued, indicating that 99mTc-MAG3 is not excreted in these kidneys. The plateau activity in UUO kidneys was relatively low (~40% of sham kidney's peak activity) as early as day1 post surgery, demonstrating that uptake of 99mTc-MAG3 is rapidly reduced in UUO kidneys. The time to plateau in UUO kidneys exceeded 200 sec, suggesting that 99mTc-MAG3 is slowly up-taken in these kidneys. These changes advanced as the disease progressed. SIU, peak activity and TTPs were minimally changed in contra-lateral kidneys during the study period. CONCLUSIONS: Our data demonstrate that renal uptake of 99mTc-MAG3 is remarkably and rapidly reduced in UUO kidneys, while the changes are minimal in contra-lateral kidneys. The parametric analysis of TACs suggested that renal perfusion as well as tubular uptake is reduced in UUO kidneys. This imaging technique should allow non-invasive assessments of UUO renal injury and enable a more rapid interrogation of novel therapeutic agents and protocols.

[(99m)Tc-MAG3 diuretic renography in assessment of obstructive uropathy. The new test F+10SP: a step ahead in the differential diagnosis]. / Scintigrafia renale sequenziale con diuretico (99m)Tc-MAG3, nella valutazione della uropatia ostruttiva. La nuova procedura F+10SP: un passo avanti nella diagnosi differenziale.

BACKGROUND: Dilation of the renal pelvis is a problem Urologists have often to deal with. One of the key aspects is to clear if the dilation is the consequence of an obstruction to the outflow or a simple anatomic variant. Aim of this study was to compare two diuretic renographic procedures, F-15 vs the new procedure F+10SP (Seated Position) in a group of hydronephrotic patients, in order to increase the accuracy in the differential diagnosis between non-obstructive and obstructive dilation. MATERIALS AND METHODS: 34 Patients (14 male, 20 female, 18-71 yrs range), 27 pts having an unilateral hydronephrosis and 7 pts a bilateral hydronephrosis diagnosed by ultrasound, were enclosed in the study. They were subjected to two 99mTc-MAG3 diuretic renography with furosemide consecutively, with different modalities: 1) 40 mg of furosemide were administered IV to patient in supine position 15 minutes before tracer injection (Test F-15, by English); 2) the new procedure: 20 mg of furosemide were administered IV to patient in Seated Position (SP), 10 minutes after tracer injection during dynamic acquisition (Test F+10 SP). The average interval between the two tests was 7 days. Two different physicians analyzed all the tests. The results were classified as: non-obstruction (only F+10SP can distinguish between normal and dilated without obstruction), obstruction, equivocal and not applicable. RESULTS: Among the 68 renal units (RU) included in the analysis, the F+10SP test showed normal findings in 21 RU (30,8%), dilation without obstruction in 21 RU (30,8%), obstruction in 25 RU (36.8%) and equivocal result in 1 RU. The F-15 renography showed non-obstructive results in 35 RU (51.5%), obstruction in 20 RU (29.4%) and equivocal findings in 11 RU (16.1%); the test was not applicable in 2 RU (2.9%) due to insufficient renal function. Side effects reported for the F-15 renogram were hypotension in 1 patient, renal colic in 3 patients, bladder filling in 13 patients, disruption because of voiding in 4 patients. No complications were observed during or after the F+10SP renography. The 20 RU diagnosed with obstruction at the F-15 test were considered obstructed also at the F+10SP test. CONCLUSIONS: The "equivocal" test rate lowered from 16% for the F-15 test to less than 1.5% for the new F+10 SP test. The F+10SP procedure is easy, well tolerated, time saving and seems to be a more reliable tool in assessment of obstructive uropathy in adults.

One-stage tubeless antegrade ureteric stenting: a safe and cost-effective option?

INTRODUCTION: Antegrade insertion of ureteric stent has become an established mode of management of upper tract obstruction secondary to ureteric pathology. It is conventionally performed as a two-stage procedure for various reasons but, more recently, a one-stage approach has been adopted. PATIENTS AND METHODS: We discuss our experience of primary one-stage insertion of antegrade ureteric stent as a safe and cost-effective option for the management of these difficult cases in this retrospective observational case cohort study of patients referred to a radiology department for decompression of obstructed upper tracts. Data were retrieved from case notes and a radiology database for patients undergoing one-stage and two-stage antegrade stenting. It was followed by telephone survey of regional centres about the prevalent local practice for antegrade stenting. Outcome measures like hospital stay, procedural costs, requirement of analgesia/antimicrobials and complication rates were compared for the two approaches. RESULTS: a one-stage approach was found to be suitable in most cases with many advantages over the two-stage approach with comparable or better outcomes at lower costs. Some of the limitations of the study were retrospective data collection, more than one radiologist performing stenting procedures and non-availability of interventional radiologist falsely raising the incidence of two-stage procedures. CONCLUSIONS: In the absence of any clinical contra-indications and subject to availability of an interventional radiologist's support, one-stage antegrade stenting could easily be adopted as a routine approach for the management of benign or malignant ureteric obstruction.

Assessment of renal graft obstruction due to ureteral inguinal hernia: US detection and 3D MR confirmation.

In most cases, renal graft obstruction is caused by ureteral stenosis due to ischemia or technical error. Exceptional cases have been published where the obstacle was the result of incarceration of the ureter in an inguinal hernia. We report a case of this type, which prompt assessment was possible due to ultrasound and magnetic resonance imaging with 3D reconstruction.

Direct primary or secondary percutaneous ureteral stenting: what is the most compliant option in patients with malignant ureteral obstructions?

The objective of this study was to analyze three ureteral stenting techniques in patients with malignant ureteral obstructions, considering the indications, techniques, procedural costs, and complications. In the period between June 2003 and June 2006, 45 patients with bilateral malignant ureteral obstructions were evaluated (24 males, 21 females; average age, 68.3; range, 42-87). All of the patients were treated with ureteral stenting: 30 (mild strictures) with direct stenting (insertion of the stent without predilation), 30 (moderate/severe strictures) with primary stenting (insertion of the stent after predilation in a one-stage procedure), and 30 (mild/moderate/severe strictures with infection) with secondary stenting (insertion of the stent after predilation and 2-3 days after nephrostomy). The incidence of complications and procedural costs were compared by a statistical analysis. The primary technical success rate was 98.89%. We did not observe any major complications. The minor complication rate was 11.1%. The incidence of complications for the various techniques was not statistically significantly. The statistical analysis of costs demonstrated that the average cost of secondary stenting (637 euros; SD, 115 euros) was significantly higher than that of procedures which involved direct or primary stenting (560 euros; SD, 108 euros). We conclude that one-step stenting (direct or primary) is a valid option to secondary stenting in correctly selected patients, owing to the fact that when the procedure is performed by expert interventional radiologists there are high technical success rates, low complication rates, and a reduction in costs.

[Multislice CT arteriography in the pre-surgical evaluation of patients with ureteropelvic junction stenosis]. / La arteriografía por tomografía computarizada multicorte en la valoración prequirúrgica de pacientes con estenosis de la unión pieloureteral.

INTRODUCTION: The current treatment of choice for ureteropelvic stenosis is endopyelotomy, but the presence of vessels in contact with the stenotic area of the ureteropelvic junction reduces the success of these interventions and increases vascular and hemorrhagic complications. The aim of our study was to use multislice CT arteriography to evaluate patients prior to surgery for ureteropelvic junction stenosis. PATIENTS AND METHODS: 16 patients with ureteropelvic junction stenosis underwent multislice CT arteriography; multidirectional images and three-dimensional reconstructions were used to identify and characterize vessels in contact with the stenotic area of the ureteropelvic junction. RESULTS: A total of eight vessels (four arteries and four veins) in six (38%) patients were found in contact with or passing within 2 mm of the ureteropelvic junction. The vessels were located anterior to the junction in four cases; it was posterior in one case, and anteromedial in the other. Endopyelotomy was contraindicated in the six patients in whom vessels were found in contact with the ureteropelvic junction. The presence of the vessels was confirmed during surgery in five of these patients; the remaining patient did not undergo surgery). CONCLUSION: Multislice CT arteriography allows adequate presurgical evaluation of ureteropelvic junction stenosis, detecting the presence of crossing vessels and facilitating the planning of the surgical approach in these patients.

Multidetector computed tomography arteriography in the preoperative assessment of patients with ureteropelvic junction obstruction.

BACKGROUND: Nowadays, endoscopic management of ureteropelvic junction (UPJ) obstruction is the treatment of choice. However, in the presence of crossing vessels, the success rate of endoscopic management decreases and the risk of hemorrhagic and vascular complications rises. The purpose of this study is to evaluate patients with UPJ obstruction using contrast enhanced multidetector computed tomography (CT) angiography to aid in surgical planning and management. PATIENTS AND METHODS: Between 2001 and 2005, 27 patients (mean age: 43 years; age range: 17-75 years) with UPJ obstruction were studied with multidetector CT angiography. Identification and characterization of crossing vessels was performed with multidirectional images and three-directional reconstructions. RESULTS: 12 patients (44%) were found to have 16 crossing vessels (vessels in contact with the UPJ or within a vicinity of less than 2 mm). Nine of these vessels were arteries and seven were veins. Nine vessels crossed anteriorly, two posteriorly, and one anteromedially. Endopyelotomy was contraindicated in these 12 patients due to the presence of crossing vessels. Eleven out of the 12 patients underwent a pyeloplasty by open surgery or laparoscopy, where the presence of crossing vessels was confirmed. One of the 12 patients did not undergo surgery. CONCLUSION: Multidetector CT angiography permits an adequate preoperative assessment of patients with UPJ obstruction as it is able to identify the presence and location of crossing vessels. Furthermore, it allows to study in detail the anatomy of the renal area and its vascular variants.