Congenital solitary kidney with renovascular hypertension diagnosed by means of captopril-enhanced renography and magnetic resonance angiography.
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A 24 year-old woman had a congenital solitary kidney with renovascular hypertension due to fibromuscular dysplasia. She had been treated as having essential hypertension until she developed preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome at 28 weeks of gestation. Plasma renin activity and captopril test results did not indicate any abnormalities. However, renography revealed captopril-induced deterioration. Magnetic resonance angiography was also useful to detect renal artery stenosis. These findings were confirmed by renal angiography. After successful percutaneous transluminal renal angioplasty, her blood pressure and the pattern of captopril renography normalized. (+info)
The F + 0 protocol for diuretic renography results in fewer interrupted studies due to voiding than the F - 15 protocol.
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Timing of diuretic administration is not universally standardized in renography. Over the past year, our practice has changed from F-15 administration of furosemide to an F + 0 protocol. Therefore, we have retrospectively compared these 2 cohorts to assess if the shorter interval between diuretic administration and study completion in the F + 0 study results in a greater frequency of patients able to complete the subsequent 30-min dynamic acquisition without disruption due to voiding. METHODS: We identified 108 diuretic (99m)Tc-mercaptoacetyltriglycine renograms performed in the previous 18-mo period. Three patients were given furosemide at 30 min after the radiopharmaceutical and were excluded. Twenty studies in children under 3 y of age were excluded from consideration because voiding is neither restricted in this age group nor does voiding into a diaper cause disruption. Forty milligrams of furosemide were administered to adults, whereas 0.5 mg/kg was given to children. In the first cohort of 56 studies, radiopharmaceutical was administered 15 min after furosemide (F-15), whereas, in the second cohort of 29 patients, it was administered immediately thereafter (F + 0). In all cases, patients were asked to void proximal to radiopharmaceutical injection. Dynamic images and renogram curves were inspected for evidence of interruption or voiding midstudy. Statistical significance was determined by a 1-tailed Fisher exact test for proportions, with P < 0.05. RESULTS: The F-15 and F+0 groups of patients were comparable in terms of age, sex, and diuretic amount. In 17 of the F-15 patients, renography was interrupted because of voiding (30%), whereas this occurred in only 3 of the F + 0 patients (10%). This difference was significant at the P = 0.033 level. The mean time of voiding was 18.3 min (range, 12-25 min) for F-15 patients and 16 min (range, 12-19 min) for the F + 0 group. CONCLUSION: The F + 0 renal diuretic protocol is associated with a significantly lower rate of disruption because of voiding than the F-15 protocol, likely due to the shorter period between diuretic administration and study termination, which results in less bladder distention and discomfort. On the basis of these data, the F + 0 protocol appears to be a more tolerable procedure. (+info)
Future direction of renal positron emission tomography.
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Positron emission tomography (PET) is perfectly suited for quantitative imaging of the kidneys, and the recent improvements in detector technology, computer hardware, and image processing software add to its appeal. Multiple positron emitting radioisotopes can be used for renal imaging. Some, including carbon-11, nitrogen-13, and oxygen-15, can be used at institutions with an on-site cyclotron. Other radioisotopes that may be even more useful in a clinical setting are those that either can be obtained from radionuclide generators (rubidium-82, copper-62) or have a sufficiently long half-life for transportation (fluorine-18). The clinical use of functional renal PET studies (blood flow, glomerular filtration rate) has been slow, in part because of the success of concurrent technologies, including single-photon emission computed tomography (SPECT) and planar gamma camera imaging. Renal blood flow studies can be performed with O-15-labeled water, N-13-labeled ammonia, rubidium-82, and copper-labeled PTSM. With these tracers, renal blood flow can be quantified using a modified microsphere kinetic model. Glomerular filtration can be imaged and quantified with gallium-68 EDTA or cobalt-55 EDTA. Measurements of renal blood flow with PET have potential applications in renovascular disease, in transplant rejection or acute tubular necrosis, in drug-induced nephropathies, ureteral obstruction, before and after revascularization, and before and after the placement of ureteral stents. The most important clinical application for imaging glomerular function with PET would be renovascular hypertension. Molecular imaging of the kidneys with PET is rather limited. At present, research is focused on the investigation of metabolism (acetate), membrane transporters (organic cation and anion transporters, pepT1 and pepT2, GLUT, SGLT), enzymes (ACE), and receptors (AT1R). Because many nephrological and urological disorders are initiated at the molecular and organelle levels and may remain localized at their origin for an extended period of time, new disease-specific molecular probes for PET studies of the kidneys need to be developed. Future applications of molecular renal imaging are likely to involve studies of tissue hypoxia and apoptosis in renovascular renal disease, renal cancer, and obstructive nephropathy, monitoring the molecular signatures of atherosclerotic plaques, measuring endothelial dysfunction and response to balloon revascularization and restenosis, molecular assessment of the nephrotoxic effects of cyclosporine, anticancer drugs, and radiation therapy. New radioligands will enhance the staging and follow-up of renal and prostate cancer. Methods will be developed for investigation of the kinetics of drug-delivery systems and delivery and deposition of prodrugs, reporter gene technology, delivery of gene therapy (nuclear and mitochondrial), assessment of the delivery of cellular, viral, and nonviral vectors (liposomes, polycations, fusion proteins, electroporation, hematopoietic stems cells). Of particular importance will be investigations of stem cell kinetics, including local presence, bloodborne migration, activation, seeding, and its role in renal remodeling (psychological, pathological, and therapy induced). Methods also could be established for investigating the role of receptors and oncoproteins in cellular proliferation, apoptosis, tubular atrophy, and interstitial fibrosis; monitoring ras gene targeting in kidney diseases, assessing cell therapy devices (bioartificial filters, renal tubule assist devices, and bioarticial kidneys), and targeting of signal transduction moleculas with growth factors and cytokines. These potential new approaches are, at best, in an experimental stage, and more research will be needed for their implementation. (+info)
Intermittent hydronephrosis secondary to ureteropelvic junction obstruction: clinical and imaging features.
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OBJECTIVE: We sought to assess the clinical and imaging findings in intermittent hydronephrosis secondary to ureteropelvic junction obstruction, with particular emphasis on the characteristic ultrasonographic findings. METHODS: This prospective, longitudinal, observational study included all children who had intermittent ureteropelvic junction obstruction and presented with abdominal pain over 6 years. Renal ultrasound was used as an initial screening tool to detect intermittent hydronephrosis. Renal ultrasonography was repeated every 1 to 2 days to record serial changes from the symptomatic to the asymptomatic stage. Their clinical manifestations and imaging findings were studied. RESULTS: Eighteen patients (14 boys, 4 girls) were studied. Most had sharp pain that began acutely and typically lasted for <2 days. Most of the children (16 of 18) had nausea and vomiting that accompanied the pain. The acute episode generally resolved spontaneously and was followed by a pain-free interval that ranged from days to months. Factors that predisposed to an attack included increased water intake, vigorous exercise, or bladder distention. All patients had clearly demonstrable obstruction of the renal pelvis during an acute attack, a finding that diminished or resolved during the symptom-free intervals. During convalescence, all patients had renal pelvic wall thickening on ultrasonography. This finding appeared on the second or third day after a painful episode subsided, persisted for 6 to 9 days, and then disappeared in the symptom-free stage. Pyeloplasty was performed in 17 patients, none of whom had recurrent pain on follow-up. Extrinsic obstructions were found in 9 patients. CONCLUSIONS: The keys to diagnosis are awareness of the syndrome, a detailed history, and immediate and serial imaging studies during painful crises. A thickened renal pelvic wall during convalescence is an important ultrasonic sign of intermittent hydronephrosis. (+info)
RENEX: an expert system for the interpretation of 99mTc-MAG3 scans to detect renal obstruction.
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A renal expert system (RENEX) has been developed to assist physicians detect renal obstruction in patients undergoing pre- and postfurosemide 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) scans. RENEX uses quantitative parameters extracted from the dynamic renal scan data and heuristic rules in the form of a knowledge base (KB) obtained from expert interpreters to conclude whether a kidney is obstructed. METHODS: Normal limits were established for 47 quantitative parameters extracted from the 99mTc-MAG3 scans of 100 potential renal donors. From these data the domain expert estimated 5 boundary conditions for each parameter: (i) definitely abnormal, (ii) probably abnormal, (iii) equivocal, (iv) probably normal, and (v) definitely normal. A sigmoid-type curve was then generated from these 5 boundary conditions, creating a parameter knowledge library used for converting the value of a prospective patient's individual quantitative parameters to a certainty factor (CF). Sixty heuristic rules were extracted from the domain expert to generate the KB for detecting obstruction. A forward-chaining inference engine was developed using the MYCIN combinatories (an approximation of Bayes theorem) to determine obstruction. A justification engine was implemented, which recorded the sequence of each rule that was fired and the current CF value of all input and output parameters at the time of instantiation to track and justify the logic of the conclusions. The entire system was fine tuned and tested using a pilot group of 32 patients (11 males, 21 females; mean age, 56.8 +/- 17.2 y; 63 kidneys) deemed by an expert panel to have 41 unobstructed kidneys, 13 obstructed kidneys,and 9 equivocal findings. RESULTS: RENEX agreed with the expert panel in 92% (12/13) of the obstructed kidneys, 93% (38/41) of the unobstructed kidneys, and 78% (7/9) of the kidneys interpreted as equivocal for obstructions. Processing time per patient was practically instantaneous using a 3.0-GHz personal computer programmed using interactive data language. CONCLUSION: We have developed a renal expert system for detecting renal obstruction using pre- and postfurosemide 99mTc-MAG3 renal scans, at a standardized expert level. These encouraging preliminary results warrant a prospective study in a large population of patients with and without renal obstruction to establish the diagnostic performance of this system. (+info)
Outcome of kidneys in patients treated for vesicoureteral reflux (VUR) during childhood.
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BACKGROUND: Outcome of renal function and blood pressure (BP) at early middle age was clarified in patients treated for vesicoureteral reflux (VUR) during childhood. METHODS: Information of renal function was available from 147 (55%) of 267 patients treated for non-obstructive VUR of any grade. Twelve patients had died of kidney-related conditions and eight had gone into terminal uraemia. A total of 127 patients participated in the study. RESULTS: The mean age of the participants was 41 years. No signs of renal scars were detected by ultrasound examination in 53 (42%) subjects. Unilateral scarring was seen in 44 (35%) and bilateral in 30 (24%) subjects. Glomerular filtration rate (GFR) showed moderate or severe renal insufficiency in four (3%) participants, all with bilateral scars. Normal GFR was found in one-third of the patients. Twenty-five (83%) subjects with bilateral scars and 60 (62%) of the other participants had abnormal GFR values (P < 0.05). Proteinuria was found in 12 (9%) and albuminuria in 30 (24%) participants. Hypertension was diagnosed earlier in 14 (11%) patients, eight having bilateral scarring (P < 0.01). Diastolic BP was significantly lower in subjects without scars compared with those having scars in one or both kidneys (P < 0.05). CONCLUSIONS: Renal function was slightly lowered in more than half of the participants. Findings of the participants with unilateral scarring or unscarred kidneys were similar, except for the increased tendency for hypertension in subjects with scars. A total of 83% of the patients with bilateral kidney scars had lowered kidney function, a quarter presented with proteinuria and a half with hypertension. Long-term follow-up for all the patients with earlier VUR is emphasized. (+info)
Radionuclide investigations of the urinary tract in the era of multimodality imaging.
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This article presents the role of nuclear medicine procedures in investigating renal and parenchymal disease, as well as upper urinary tract abnormalities. More specifically, the use of scintigraphy is described in the exploration of urinary tract dilatation and UTIs, vesicoureteric reflux, renovascular hypertension, and renal transplants. With a low radiation burden and the absence of sedation, these nuclear medicine procedures are easy to perform and can provide clinicians with valuable data on renal perfusion and the function of individual kidneys, as well as on urinary tract dynamics. However, knowledge of limitations and technical pitfalls is essential in understanding the role of scintigraphy among contemporary imaging methods and the unique information it supplies in nephrourology. (+info)
Can renal doppler sonography replace diuretic radionuclide renography in infants with hydronephrosis?
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Reliable differentiation between obstructive and non-obstructive hydronephrosis is decisive for the further therapeutic management in infants. The results of renal Doppler sonography were compared with diuretic radionuclide renography and with the follow-up results in 33 patients (range: 21 to 98 days). In Doppler sonography, a resistive index (RI) of > 0.9 was considered to be abnormal in the sense of an obstruction. In diuretic renography, a T1/2 value (time until a 50% decrease in activity in the kidneys was observed after injection of furosemide) of >20 min was appraised as obstructive hydronephrosis. In six patients an obstructive (T1/2 >20 min) and in 27 patients a non-obstructive (T1/2 <20 min) hydronephrosis was found. All patients with obstruction in diuretic renography showed an abnormal RI (>0.9) in Doppler sonography. In addition, all patients with surgery and obstruction in diuretic radionuclide renography showed an improvement in hydronephrosis. However, seven patients had a false-positive result in Doppler sonography. All patients with non-obstruction in diuretic radionuclide renography showed no worsening of hydronephrosis without surgery in the follow-up. We found a RI of 0.84 +/- 0.07 in the non-obstructive group and of 0.96 +/- 0.05 (p = 0.018) in the obstructive group. Doppler sonography showed discrepant results compared to diuretic radionuclide renography and therefore cannot replace this method. (+info)