Radionuclide Renogram Research Articles

Renal cortical transit time in the evaluation of prenatally detected presumed pelvi ureteric junction like obstruction: A systematic review.

Introduction:Differentiating nonobstructive from obstructive dilatation of the kidney is a clinical dilemma in prenatally detected hydronephrosis. Many radionuclide renogram parameters have been used to differentiate obstructed from non-obstructed units, including cortical transit time (CTT). We evaluate the role of CTT in identifying obstruction through a systematic review.Methods:A literature search of the MEDLINE, MEDLINE In-Process, and MEDLINE Epub Ahead of Print, EMBASE, Google scholar, Pub Med, and Cochrane Library was done using key words – radionuclide renogram, CTT, parenchymal transit time, cortical transit, renography to identify articles on the subject. The identified articles were assessed for appropriateness and reviewed.Results:The initial search yielded a total of 1583 articles, after adding the articles from references and applying the inclusion and exclusion criteria a total of 28 articles were selected. CTT showed good inter observer agreement in identifying obstruction. The use of CTT as a single parameter for determining the need for surgery and to identify those kidneys which will have functional improvement after surgery has been evaluated and has been found to be useful. CTT is best used in conjunction with ultrasonography to make clinical decisions.Conclusion:The commonly used visual method of estimating the CTT, is a promising parameter for the evaluation of prenatally detected pelviureteric junction obstruction. Further well-designed multicenter prospective studies are needed to establish it as the most specific parameter to differentiate obstructive from nonobstructive dilatation of the pelvicalyceal system.

Radionuclide Renogram Findings in Different Kidney Diseases Referred to Institute of Nuclear Medicine and Allied Science (INMAS)

Renal function evaluation with the use of radio nuclide scanning is a very helpful technique. Renogram is a routine procedure in the Institute of Nuclear Medicine and Allied Sciences (INMAS), Sylhet. This is a tertiary referral hospital to north east part of the country. The aim of this study was to analyze the renal disease pattern and outcome of diuretic renogram of different types of renal diseases. This retrospective study was conducted among 223 patients who underwent 99mTc-DTPA renogram from February to October 2018 in INMAS, Sylhet. Mean age of the patients was 30.04 ± 18.52 year with age range 1 to 80 years, male to female ratio 1.5:1. USG. Clinical information and other adjuvant findings along with the ultrasound findings were collected to categorize the study subject. Most common indication for the renogram was hydronephrosis (HDN) 80.27%, followed by smaller kidney 7.17%, renal parenchymal disease 3.14%, nephrolithiasis 3.14% and others (renal cysts and renal artery stenosis). The mean and standard deviation of serum creatinine was 0.9 ± 0.51, range from 0.30 to 4.50. Among the 179 HDN patients, mild, moderate and severe cases were 37 (20.7%), 44 (24.6%) and 81 (45.3%) respectively. Most common site of involvement was left kidney (n=90, 41.3%), followed by both kidneys (n=67, 30.7%). Overall renographic findings showed obstructive disease in 144 (66.05%) patients and non- obstructive disease in 74 (33.94%) patients. It concluded that isotope renogram is very important in the evaluation of renal function especially differentiate between obstructive from non-obstructive pathology.
 Bangladesh Med J. 2021 January; 50(1) : 10-14

Is decreased diameter of renal pelvis in prone position an indicator of successful pyeloplasty?

Objective:To evaluate patients who had undergone pyeloplasty for pelviureteric junction obstruction, by measuring the anteroposterior diameter (APD) of the renal pelvis in supine and prone positions, and determine whether a decrease in APD in prone position can exclude obstruction in dilated renal system.Materials and Methods:From January 2012 to December 2013, patients who had undergone pyeloplasty were evaluated by ultrasound in two centers. The difference of APD of the renal pelvis in supine and prone positions was obtained. Correlation was made with the pre- and post-pyeloplasty renal function by radionuclide renogram.Results:There were 42 patients (31 males, 11 females; age range 5 months to 18 years). Residual hydronephrosis was detected in 41 patients of whom 35 patients (85%) showed decrease in APD by >10% in prone position. These patients and the one without hydronephrosis showed either no deterioration or improvement in renal function. Six patients (15%) showed either no change or increase in APD in prone position. Three patients (7.5%) were confirmed to have decrease in renal function indicating obstruction. Three patients (7.5%) showed no deterioration of renal function, but sluggish drainage on radionuclide renogram.Conclusion:Demonstration of decreased APD of renal pelvis in prone position by ultrasound is useful to differentiate obstructed from non-obstructed dilated renal system, and it correctly identified 85% candidates with successful pyeloplasty. In patients with no decrease or increase in APD at prone position, further follow-up is recommended to rule out obstruction.

Scintigraphy in Ochoa Syndrome

The Ochoa or urofacial syndrome is a disease characterized by non-neurogenic bladder dysfunction and unusual facial expressions when smiling or crying. It is an extremely rare disorder with over 150 cases reported in the medical literature. This condition has been determined to be inherited by an autosomal recessive pattern. We present radionuclide renogram and renal scan of a boy with a history of incontinence, frequent infections of the urinary tract, and gene mutations consistent with this syndrome. Nuclear medicine images showed extensive bilateral renal scarring and obstructive pattern in diuretic renogram.

Predicting the Clinical Outcome of Antenatally Detected Unilateral Pelviureteric Junction Stenosis

To determine, in children with antenatally detected pelviureteric junction (PUJ) stenosis, what factors may be predictive for deterioration of differential renal function (DRF) in case of conservative treatment or improvement of DRF in case of pyeloplasty. This study analyzed and compared the initial level of hydronephrosis, DRF, quality of renal drainage, and cortical transit with the late DRF outcome. We reviewed the medical charts of 161 consecutive children with antenatally diagnosed PUJ stenosis during a 10-year period (between 1997 and 2007). From this cohort, we retained 81 children with unilateral PUJ and strictly normal contralateral kidney, with a median follow-up of 67 months. Repeated ultrasounds, voiding cystourethrography, and radionuclide renograms were performed in all children. Fifty patients never underwent a surgical intervention (62%), whereas surgical repair (Anderson-Hynes dismembered pyeloplasty) was performed in 31 (38%). During conservative follow-up, DRF deterioration was observed in 11% of patients. After pyeloplasty, DRF improvement was observed in 25% of patients. Abnormal cortical transit was the only predictive factor of DRF deterioration in case of conservative approach, whereas the initial degree of hydronephrosis, or renal drainage, and the initial DRF level were not predictive. In children who were operated on, only impaired cortical transit was predictive of DRF improvement postoperatively. Conservative management of children with unilateral PUJ stenosis is a safe procedure. Impaired cortical transit although imperfect, seems the best criterion for identifying children for whom pyeloplasty is warranted.

Assessing Renal Parenchymal Volume on Unenhanced CT as a Marker for Predicting Renal Function in Patients with Chronic Kidney Disease

To estimate renal volume in chronic kidney disease (CKD) patients using a semiautomated software and compare them with split renal function estimates from radionuclide renogram (RR). We proposed that renal volume from unenhanced computed tomography (CT) scans may serve as surrogate marker for assessing renal function in CKD patients. Unenhanced multidetector CT scans of 26 patients with CKD (estimated glomerular filtration rate [eGFR] <60 mL/kg/body surface area [BSA]) and 10 controls (eGFR >60 mL/kg/BSA) were analyzed to calculate renal volumes using a semiautomated software (AMIRAV5.2.0). Volumes obtained were then correlated with corresponding eGFR and split renal function estimates from RR. Volumes were also compared with those obtained on enhanced scans in 10 cases (five disease group, five controls). Bland-Altman analysis was used to assess agreement between methods. A moderately positive correlation was found between renal volume obtained on unenhanced CT and eGFR (r = 0.65, P < .0001), whereas a significantly high correlation with split function estimates from RR (r = 0.95, P < .001) was found. Bland-Altman analysis revealed a good agreement between renal volume from CT and renal function from RR (34/36 observations were within 95% CI and there were two outliers). Correlation between volumes obtained from unenhanced and enhanced CT scans was also significant (r = 0.96). In patients with CKD, renal volume derived from unenhanced CT can possibly serve as a surrogate marker for assessing and monitoring renal function reserves to plan further management.

Predictive Value of Decreased Renal Pelvis Anteroposterior Diameter in Prone Position for Prenatally Detected Hydronephrosis

It is important to differentiate between those cases of prenatally detected hydronephrosis that are significant and those that are likely to resolve spontaneously. We evaluated the anteroposterior pelvic diameter of the renal pelvis postnatally in the supine and prone positions, and determined whether the difference between these 2 positions helps predict the outcome of prenatally detected hydronephrosis. From May 2009 to June 2011, 38 infants with prenatally detected unilateral ureteropelvic junction type hydronephrosis were evaluated. The anteroposterior pelvic diameter was noted in the supine and prone positions. Functional evaluation was done by radionuclide renogram. Those with a split function of less than 40% underwent pyeloplasty. All other patients were followed by serial ultrasound examination. Six infants had an anteroposterior pelvic diameter larger than 40 mm with no change in diameter in the supine vs prone positions. Seven of 16 infants with an anteroposterior pelvic diameter between 30 and 40 mm, and 11 of 15 infants with an anteroposterior pelvic diameter between 15 and 30 mm had a smaller anteroposterior pelvic diameter in the prone position. These infants had normal renal function, improvement in hydronephrosis and did not need pyeloplasty. All the infants with no change in anteroposterior pelvic diameter in either position had poorer renal function, necessitating pyeloplasty. Those cases of prenatally detected ureteropelvic junction type of hydronephrosis in which the anteroposterior pelvic diameter is smaller in the prone position than in the supine position showed improvement in hydronephrosis, while those with no change in anteroposterior pelvic diameter had worsening of hydronephrosis and needed surgical intervention.

Mise au point postnatale des dilatations des voies urinaires de diagnostic anténatal

Fetal pyelectasis is the most frequently encountered anomaly on prenatal ultrasound. The ultrasound diagnostic criteria are well established: nature of dilated structures, degree of dilatation, ultrasound appearance of the kidneys, volume of amniotic fluid. Ultrasound can also determine if the anomaly is isolated or not, which is important for the management and prognosis of the pregnancy. Ultrasound is the initial postnatal study to evaluate the urinary tract. Further management will be based on suspected diagnosis. In cases of suspected vesico-ureteral reflux, VCUG is performed. In cases of obstructive uropathy or complex malformation (duplications), MRI is performed at 6 months of age to further define the anatomy of the urinary tract. Radionuclide renogram, performed in most cases, allows evaluation of split renal function. Follow-up ultrasound is important to monitor renal development, urinary tract dilatation and appearance of the renal parenchyma. Functional follow-up is assured by radionucline renography. This comprehensive follow-up is recommended to prevent complications and progressive loss of renal function.

Acute bilateral renal infarction secondary to cocaine-induced vasospasm

CASE PRESENTATION A 47-year-old African-American male with a history of hypertension for 1 year and cocaine use presented to the emergency department with acute onset of bilateral flank pain, nausea, vomiting, and diarrhea. Physical examination was unremarkable. Laboratory evaluation revealed a white blood count of 15.1 K/μl (normal 4.5-11.5 K/μl) and a serum creatinine of 2.4mg/100ml. A non-contrast CT scan of the abdomen was unremarkable. The patient was treated with morphine (for pain) and i.v. fluids, felt better, and was discharged for out-patient follow-up. The patient saw his primary care physician 2 days later (day 3) and reported persistence of the bilateral flank pain. The patient also reported a transient inability to urinate for 36 h before the visit. An abdominal ultrasound and blood chemistry were obtained. On day 5, he was referred by his physician to the emergency department for a serum creatinine of 9.2 mg/100 ml from day 3. At the time of admission, the patient reported using 5-6g/day of ibuprofen for the previous 4 days and admitted to sniffing cocaine a few hours before the initial onset of flank pain. On physical examination, the patient was a well-built African-American male with a temperature of 99.2 °F, pulse rate of 60/min, blood pressure of 150/85 mm Hg and weight of 85 kg (BMI 27.7 kg/m 2 ). There was no orthostasis, pallor, or skin rash. The heart and lung examinations were unremarkable. The abdomen was soft, with no suprapubic dullness. There was no costovertebral angle tenderness or pitting edema. The extremity pulses were symmetric and equal. Laboratory results are presented in Table 1. Serologic tests for hepatitis B and C viruses, human immunodeficiency virus, antinuclear antibody, and rheumatoid factor were negative. Serum complements, including C3, C4, and CH50, were within the normal range. Hemoglobin electrophoresis, chest X-ray, electrocardiogram, and echocardiogram were unremarkable. Renal ultrasound revealed normal-sized kidneys with mildly increased echogenecity and no hydronephrosis. A 99m Tc-MAG3 (mercaptoacetyltriglycine) radionuclide renogram showed multiple wedge-shaped photopenic areas in both kidneys (Figure 1a). Owing to the absence of a clear explanation for the patient's acute renal failure, renal biopsy was performed 12 days after the onset of symptoms.

Levels of GFR and Protein-induced Hyperfiltration in Kidney Donors: A Single-Center Experience in India

Some studies have shown that the normal range of glomerular filtration rate (GFR) was lower in an Indian population than in western populations. To verify these findings and determine whether it is physiological or an expression of subclinical disease, we measured GFR in a cohort of healthy Indian adults by using more stringent criteria to define "healthy" than used in previous studies. Cross-sectional study. 109 healthy adults being evaluated for kidney donation with normal blood pressure, body mass index, urinalysis results, and protein excretion and symmetrical function on radionuclide renogram. Subjects followed a vegetarian diet with 1 g/kg of protein intake for 10 days before the study. Age, sex, relation to recipient (relative versus spouse), body surface area, body mass index, kidney size, serum creatinine level, and urinary protein-creatinine ratio. OUTCOME AND MEASUREMENTS: GFR measured as plasma clearance of technetium 99m diethyl-triamine-penta-acetic acid before and after amino-acid infusion (protein-induced hyperfiltration). Measurements were performed after a 12-hour fast. Mean baseline GFR was 82.4 +/-12.7 mL/min/1.73 m(2) (95% confidence interval, 80.0 to 84.8). Mean stimulated GFR was 104.7 +/- 16.1 mL/min/1.73 m(2) (95% confidence interval, 101.6 to 107.8). Measured mean protein-induced hyperfiltration was 27.3% +/- 10.04% (range, 6.7% to 56%). In multivariable linear regression analysis, younger age, spousal donor, and larger average kidney size were associated with significantly greater baseline GFR, and only greater baseline GFR was associated significantly with stimulated GFR. Dietary protein intake was not measured; a habitual low-protein diet cannot be excluded as a cause of low GFR. Basal GFR is significantly lower than the normal value of 120 to 130 mL/min/1.73 m(2) in western populations. The conventional cutoff value of 60 mL/min/1.73 m(2) for defining chronic kidney disease might not be appropriate in India.

Do Captopril Renogram and Losartan Renogram Influence the Choice of Drug (Angiotensin Converting Enzyme Inhibitor/Angiotensin II Receptor Blocker) to be Initiated in Renal Patients?

The objectives of this study were to investigate the effects of angiotensin converting enzyme (ACE) inhibitors and angiotensin (AT) II receptor blockers on glomerular filtration rate (GFR) as measured by radionuclide renogram study, and to assess the value of changes in GFR modification with AT-II receptor blocker/ACE inhibitor in determining the drug choice between ACE inhibitors and AT-II receptor blockers. Methods: A total of 14 patients with type 2 diabetes or hypertension were subjected to baseline diethylene triamine pentaacetic acid (DTPA) renogram followed by captopril and losartan renograms. The patients were followed in a prospective randomized controlled crossover trial. Patients were treated with either enalapril or losartan initially for 6 months, followed by the other drug in the later 6 months of the study period. Patients with renal arterial disease, obstructive uropathy, urinary tract infection, acute renal failure or serum creatinine more than 3 mg/dL were excluded from the study. Our data showed that irrespective of the initial choice of drug, either ACE inhibitor or AT-II receptor blocker, there was an initial fall in GFR (noticed at 3 and 6 months) followed by an increase in GFR at the end of 1 year. But neither the initial fall in GFR nor serum creatinine at the end of 6 months were different. This shows that initial fall in GFR might not be associated with a rise in serum creatinine. Patients may respond differently after intervention with captopril or losartan as evidenced by radionuclide renogram study. The acute decline in GFR after captopril and losartan may be a pointer to the utility of radionuclide DTPA renogram study in choosing which drug - ACE inhibitor or AT-II receptor blocker - to use in patients requiring them. An acute increase in GFR may not always suggest lack of benefit with that particular drug. This is especially true with AT-II receptor blockers, where the effects of AT2 receptors appear to have an influential role.

At what level of unilateral renal impairment does contralateral functional compensation occur?

Functional compensation occurs in a kidney when the function of the contralateral kidney is decreased or absent. What is, however, not documented is the level of unilateral renal impairment at which functional compensation occurs. Split function, as obtained from a radionuclide renogram, can only show the asymmetry between both kidneys. The aim of the present work was to evaluate at what level of unilateral impairment a functional compensation can be observed in the contralateral normal kidney. From a large database, 180 children over 2 years of age with unilateral pathology were retrospectively selected. All of them underwent a radionuclide study, combining a technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3) renogram associated with a chromium-51 ethylenediaminetetraacetic acid (Cr-51 EDTA) overall clearance, allowing a precise estimation of single-kidney glomerular filtration rate (SKGFR). Below 30-35 ml/min/1.73 m2, there was a significant inverse correlation between SKGFR on the normal and the abnormal side. Above this level, no such correlation was observed, the mean SKGFR on the normal side remaining around 58 ml/min/1.73 m2, whatever the value of SKGFR on the abnormal side. In pediatric patients, hyperfunction occurs when SKGFR of the diseased kidney is below 30-35 ml/min/1.73 m2.

MR renography using a dynamic gradient-echo sequence and low-dose gadopentetate dimeglumine as an alternative to radionuclide renography.

Our aim was to evaluate the feasibility of acquiring an MR signal intensity-time renographic curve and dynamic serial images in a way similar to that of acquiring radionuclide renograms, with a dynamic gradient-echo sequence and a low-dose gadopentetate dimeglumine technique, using a commonly available 1.5-T MR scanner. SUBJECTS AND METHODS. Patients who underwent both radionuclide and MR renographic studies within a 3-month period were included in the analysis. This yielded 21 studies from 19 patients. Nineteen of the 21 studies were available for analysis. Two studies were excluded because of technical errors during MR renographic acquisition. Serial MR renograms were obtained using a dynamic two-dimensional spoiled gradient-echo fast low-angle shot T1-weighted sequence. Low-dose IV furosemide and gadopentetate dimeglumine (0.025 mmol/kg of body weight) were administered. Intensity-time curves were obtained from the manually selected regions of interest over the renal parenchyma and whole kidney for calculation of split renal function and assessment of urinary excretion, respectively. Results were compared with those obtained with radionuclide renography. Good correlation (Pearson's correlation coefficient, r = 0.97, p < 0.001) was observed when the volume-corrected split renal function acquired with MR renography was compared with that obtained with radionuclide renography. There was also good agreement in the excretory curve patterns (weighted kappa(observer 1) = 0.77 and kappa(observer 2) = 0.81) between the two techniques. Dynamic MR gradient-echo imaging with a low-dose gadopentetate dimeglumine technique can produce an intensity-time curve and serial dynamic images of the urinary system, in a way similar to that of radionuclide renography. This technique allows assessment of split renal function and urinary excretory status and is a feasible alternative to radionuclide renography.

The Use of the Tissue Adhesive Enbucrilate (Histoacryl®) in the Treatment of Symptomatic Nephroptosis

Purpose: To evaluate the use of the tissue adhesive enbucrilate in the treatment of symptomatic nephroptosis. Materials and Methods: We performed adhesive nephropexy in 9 patients who presented with well-documented symptomatic nephroptosis that was demonstrated with intravenous pyelography and/or radionuclide renogram studies. The ptotic kidney was fixed on the psoas muscle using 0.5 ml of enbucrilate (Histoacryl^®). Results: Adhesive nephropexy was successful in all 9 patients. Average operative time was 37 min. Postoperative opioid analgesia duration and hospital stay were limited (mean 2 and 4.4 days, respectively). Most patients returned to normal activity within 2 weeks (mean 14.2 days). Mean follow-up was 25 months and showed postoperatively a good anatomical result in radiographic studies as well as significant pain alleviation (mean 1 vs. 7 preoperatively, on a 10-point scale, p < 0.005 Wilcoxon rank test). Conclusions: The tissue adhesive enbucrilate seems to be a safe, efficient agent to obtain good results in a simple, quick approach in the surgical treatment of symptomatic nephroptosis.

Tc-99m MAG3 Renal Studies: Renogram and Effective Renal Plasma Flow in Spinal Cord Injury Patients

To determine whether years since injury, level of injury, degree of injury, gender, or age influence renal function in 66 spinal cord injuries (SCI) patients without urological complications, individual kidney effective renal plasma flow (ERPF) and radionuclide renogram (RR) were measured using technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3). The 176 individual kidneys included 84 kidneys with normal ERPF and RR, 48 kidneys with normal ERPF but abnormal RR, and 44 kidneys with abnormal ERPF and RR. The incidence of abnormal Tc-99m renal study results was higher in the kidneys of female patients (37/54, 68%) than of male patients (55/122, 45%) (p < 0.05). We found that Tc-99m MAG3 renal studies including ERPF and RR are safe and noninvasive urological screening tests for SCI patients.

Renographic indices for evaluation of changes in graft function.

Radionuclide renal diagnostic studies play an important role in assessing renal allograft function, especially in the early post-transplant period. In the past two decades various quantitative parameters have been derived from the radionuclide renogram to evaluate changes in perfusion and/or function of the kidney allograft. In this review article we discuss the quantitative parameters that have been used to assess graft condition, with emphasis on the early postoperative period. These quantitative methods are divided into parameters used for assessing renal graft perfusion and parameters used for evaluating parenchymal function. The blood flow in renal transplants can be quantified (a) by measuring the rate of activity appearance in the kidney graft, (b) by calculating the ratio of the integral activity under the transplanted kidney and arterial curves and (c) by calculating the renal vascular transit time. In this article we review a number of parenchymal uptake and excretion indices, such as the accumulation index, the graft uptake capacity at 2 and 10 min, the excretion index and the elimination index. The literature on these parameters shows that they have some practical disadvantages. In addition, values suffer from significant overlap when various graft pathologies coexist. A retrospective study was designed in our institution to evaluate the clinical usefulness of some of the frequently used previously published methods in which the graft function is quantitatively assessed in the early post-transplant period. The quantitative parameters studied which were reasonably reproducible in our hands included: global perfusion index (GPI), cortical perfusion index (CPI), vascular transit time, and the parenchymal parameters uptake capacity at 2 min (UC2) and elimination index (K3/20). The patient population in this study consisted of 43 patients with 157 technetium-99m mercaptylacetyltriglycine renograms. The perfusion indices GPI and CPI did not allow differentiation of the acute tubular necrosis (ATN) group from the acute rejection (AR) group; however, they were of value in monitoring the improvement in the condition of the graft dysfunction in both the AR and ATN groups. As for the parenchymal parameters, both UC2 and K3/20 were able to differentiate stable graft function (SGF) versus AR and ATN groups but were unable to separate AR from ATN dysfunction. The ability of these parenchymal parameters to detect improvement in the graft function was poor and statistically non-significant. From the literature data and our own findings it is concluded that radionuclide scintigraphy of renal transplants has assumed an important role, especially if performed serially, in monitoring graft function in the post-transplant period. Many quantitative parameters have been derived from the radionuclide renogram to evaluate changes in perfusion and/or function of the kidney allograft. It appears that these quantitative numerical values are unable to differentiate unequivocally between grafts with ATN and AR cases. The real value of these parameters lies in the follow-up of the dysfunction processes, which helps the clinician to determine the appropriate therapeutic regimen.

Quantitative scintigraphic parameters for the assessment of renal transplant patients

Radionuclide renal diagnostic studies play an important role in assessing renal allograft function especially in the early post transplant period. In the last two decades various quantitative parameters have been derived from the radionuclide renogram to facilitate and confirm the changes in perfusion and/or function of the kidney allograft. In this review article we discuss the quantitative parameters that have been used to assess graft condition with emphasis on the early post-operative period. These quantitative methods were divided into parameters used for assessing renal graft perfusion and parameters used for evaluating parenchymal function. The blood flow in renal transplants can be quantified by measuring (a) the rate of activity appearance in the kidney graft; (b) the ratio of the integral activity under the transplanted kidney and arterial curves e.g. Hilson’s perfusion index and Kircher's kidney/aortic ratio; (c) calculating the renal vascular transit time by deconvolution analysis. The literature overview on these parameters showed us that they have some practical disadvantages of requiring high quality bolus injection and numerical variations related to changes in the site and size of regions of interest. In addition, the perfusion parameter values suffer from significant overlap when various graft pathologies coexist. Quantitative evaluation of the graft parenchymal extraction and excretion was assessed by parameters derived from 123I/ 131I-OIH, 99mTc-DTPA or 99mTc-MAG3 renograms. We review in this article a number of parenchymal parameters which include (1) plasma clearance methods like glomerular filtration rate (GFR) and effective renal plasma flow (ERPF); (2) renal transit times such as parenchymal mean transit time, T max, T 1/2; (3) parenchymal uptake and excretion indices as the accumulation index, graft uptake capacity at 2 and 10 min, excretion index and elimination index. These indices, however, are non-specific and far from defining a specific cause for graft parenchymal dysfunction. In conclusion, despite that the literature is replete with mathematical strategies for quantitating perfusion and parenchymal functions, none of these have enough diagnostic power for specific diagnosis of graft dysfunction. In addition, no universal agreement on the use of certain quantitation parameters in transplant patients has been reached.

Renal pyelectasis in fetuses and neonates: diagnostic value of renal pelvis diameter in pre- and postnatal sonographic screening.

Pre- and postnatal pyelectasis detected by sonographic screening is of questionable pathologic importance. Therefore, we defined the natural course and diagnostic value of renal pelvis diameter (RPD) during fetal life and the neonatal period as such dilatation was revealed on routine sonography. Routine sonography in pregnant women was obtained between gestational weeks 22 and 30. Sonograms were obtained for 1021 fetuses, of which 15 could not be followed up as neonates. The remaining 1006 fetuses also underwent neonatal sonography. All neonates with an RPD larger than 5 mm were followed up sonographically. Neonates with an RPD larger than 9 mm or persistent widening (> 5-9 mm) were examined by voiding cystourethrogram, radionuclide renogram, or both. Thirty fetuses (3%) had an RPD larger than 5 mm. Nine of these fetuses also had an RPD larger than 5 mm as neonates. Of these nine neonates, one had bilateral grade II vesicoureteric reflux (VUR) and two had urinary tract obstructions (one posterior urethral valve and one ureteropelvic junction obstruction). Forty-nine neonates whose results on fetal sonograms had been normal showed an RPD larger than 5 mm on neonatal sonograms. Grade III VUR was found in one boy, and ureteropelvic junction obstruction was found in two boys. The kidneys of 54 neonates who showed an RPD larger than 5 mm without urinary tract obstruction were followed up until an RPD of 0-5 mm was evident. RPD normalized within 1 year of birth, whether VUR was present or not. Symptomatic urinary tract infection was diagnosed in 17 infants who had no renal pelvis dilatation seen on pre-or postnatal screening during the observation period. Seven of the 17 neonates had VUR. Conversely, none of the infants with pre- postnatal dilatation presented with symptomatic urinary tract infection. However, in one neonate an asymptomatic urinary tract infection without VUR was diagnosed by routine urinalysis. In our study, we linked renal pelvis dilatation on pre- and postnatal sonograms to obstructive uropathies rather than to vesicoureteric reflux. Prenatal sonography proved less sensitive than postnatal sonography in revealing obstructive uropathies. An RPD smaller than 10 mm on neonatal sonography was of no pathologic significance because renal collecting systems normalized spontaneously in all infants within 1 year of birth. These neonates and infants had no significant risk for urinary tract infection and did not need further evaluation.

Magnetic resonance renography: Optimisation of pulse sequence parameters and Gd-DTPA dose, and comparison with radionuclide renography

The aim of this study was to assess the feasibility of magnetic resonance renography (MRR) using gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) in comparison with conventional radionuclide renography (RR) using technetium-99m-DTPA ( 99mTc-DTPA). MRR has many advantages over RR, including lack of ionising radiation, increased spatial resolution, and visible background anatomy. By optimising the pulse sequence, we developed an MRR protocol in which signal intensity is linear with Gd-DTPA concentration over a clinically relevant range. Twenty-nine patients and a volunteer were studied using this protocol. Magnetic resonance renography was performed using three different doses of Gd-DTPA: 0.1 mmol kg −1 ( n = 13), 0.05 mmol kg −1 ( n = 7), and 0.025 mmol kg −1 ( n = 9). Each patient was also assessed using radionuclide renography. The resulting renograms were assessed in terms of time to peak signal intensity, signal decrease after peak, and kidney function ratios calculated from both the areas underneath and the slopes of the uptake curves. We have shown that the MR renograms obtained using low dose Gd-DTPA correlate best with the radionuclide renograms. Remaining discrepancies may be explained by variations in the injection procedures (hence in arterial input functions) and the limited coverage of the three MRR slices compared to the whole body projection of RR. Furthermore, at high local concentrations, signal becomes independent of T 1 and is dominated by T 2 ∗ .

Detection of obstructive uropathy in the fetus: predictive value of sonographic measurements of renal pelvic diameter at various gestational ages.

The goal of our study was to analyze the fetal renal pelvic diameters measured sonographically at several gestational intervals in live-born neonates subsequently found to have either obstructive uropathy or normal kidneys. This information will improve the efficacy of sonography in the diagnosis of obstructive uropathy. From an ongoing prospective study assessing the significance of fetal renal pelvic diameters of 4 mm or more at obstetric sonography, the findings in 29 obstructed kidneys in 24 babies were compared with the findings in 380 kidneys from 233 infants who had no obstruction. Twenty-three infants had unilateral obstruction of the ureteropelvic junction, two had unilateral renal obstruction at the ureterovesical junction, one had posterior urethral valves and in addition had both kidneys obstructed because of obstruction at the ureterovesical junction, one kidney was obstructed because of megaloureter, and one kidney was obstructed because of obstruction in a duplex collecting system. Obstruction was identified on nephrostograms, excretory urograms, or radionuclide renograms. The sonographic findings were compared at three gestational age ranges: 16-23 weeks' gestation, 24-30 weeks' gestation, and 31-40 weeks' gestation. The progression of pelvic dilatation in both groups (12 obstructed and 86 unobstructed) was analyzed for the subset of kidneys examined in all three time periods. At 16-23 weeks' gestation, the difference in mean pelvic diameter between obstructed and unobstructed kidneys was not statistically significant, but the difference between obstructed and unobstructed groups at 24-30 weeks' and 31-40 weeks' gestation was significant (p < .001). Renal pelvic diameter showed a much greater rise in diameter through pregnancy in the obstructed group than in the unobstructed group (p < .0003). The sensitivity of the cutoff point of 4-mm renal pelvic diameter for detecting obstruction was 76% before 23 weeks' gestation, including kidneys with a marked decrease in function postnatally; the sensitivity of a 10-mm cutoff point at 16-23 weeks' gestation was 12%. The likelihood that a fetus had renal obstruction increased with increasing diameter of the fetal renal pelvis in all three time periods. Kidneys with significant obstruction postnatally may have no dilatation of the renal pelvis before 23 weeks' gestation. Most obstructed kidneys had pelvic diameters of less than 10 mm before 23 weeks' gestation. During pregnancy, renal pelvic diameter increases at a greater rate in kidneys that later are shown to be obstructed than in those that are not obstructed.