Inter- and intra-observer reproducibility of quantitative renographic parameters of differential function and renal drainage in children.

PURPOSE: To evaluate inter- and intra-observer reproducibility of renographic quantitative parameters of input and output in children. METHODS: 100 children with unilateral or bilateral uropathy were selected, aiming to cover the entire range of ages, overall glomerular filtration rate (GFR), differential renal function (DRF) and quality of drainage. Renograms were acquired and processed according to the EANM guidelines, using a non-commercial software. Following parameters were tested: DRF using integral and Patlak methods, normalized residual activity (NORA) and output efficiency (OE) at 20 min and on the late post-erect post-micturition acquisition. Three observers from the same department and one from Santiago (Chile) processed independently the 100 renograms using the same renal software. Two observers reprocessed the 100 renograms again two months later in order to evaluate the intra-observer reproducibility. RESULTS AND CONCLUSION: No significant difference was observed between the four observers, whatever the considered parameter of input function or output. For left DRF (Integral and Patlak methods), 95% of the individual differences were between -5% and +5 %. They were between -0.5 and +0.5 units for both NORA 20 and NORA PM, and between -10% and +10% for OE 20 and OE PM. Inter-and intra- observer reproducibility were comparable. Outliers tended to be more frequent for Patlak than for Integral. Very low GFR (< 20 mL/min/1.73 m(2)), very young age (first days of life), huge megaureters, NORA values higher than 2.0, OE values below 60% and bladder in the renal background area (ectopic kidney) were the main characteristics of extreme differences.

Late renal sequelae in intravenously treated complicated urinary tract infection.

BACKGROUND: The treatment of complicated urinary tract infection in children is still a matter of debate. In our hospital, antimicrobial treatment is initiated intravenously, and the duration of this treatment is adapted according to the results of a Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy. AIM: This study was conducted to evaluate retrospectively the frequency and the importance of late renal sequelae when treating intravenously for 7 days those patients with an abnormal acute DMSA. METHODS: A review was conducted of the medical charts of all patients consecutively admitted between 2005 and 2008 with positive urine culture and clinical and biological evidence of complicated urinary tract infection (UTI). RESULTS: There were 144 patients (59 %) with abnormal early DMSA scintigraphy and 98 (41 %) with normal scintigraphy. The median duration of intravenous treatment was 7.0 days in the children with DMSA lesions and 5.0 days in those without lesions. Obvious renal sequelae were observed on late DMSA scintigraphy in 4 (6 %) out of the 65 patients with an abnormal early DMSA who came back for control scintigraphy. CONCLUSION: Sequelae of acute DMSA lesions observed during complicated UTI treated 7 days intravenously were infrequent. Whether the mode and duration of antimicrobial treatment might explain the low rate of sequelae remains to be demonstrated.

Is normalized residual activity a good marker of renal output efficiency?

BACKGROUND: Output efficiency (OE) and normalized residual activity (NORA) are two parameters that allow quantifying the renal drainage at any moment of renographic acquisition. Although OE is theoretically more accurate than NORA in case of a decreased overall renal function, both parameters present some weaknesses. OBJECTIVES: To compare both parameters and to evaluate whether the clinical information provided by both parameters is identical. METHODS: From a large database of Tc-99m mercaptoacetyltriglycine 3 renographic studies, 450 kidneys were selected covering a large range of ages, overall function, split function, and quality of drainage. NORA and OE were calculated at the end of the 20-min renogram, as well as on the late post erect postmicturition (PM) views. RESULTS: An inverse correlation was observed between NORA 20 and OE 20 (r=-0.926), as well as between NORA PM and OE PM (r=-0.936). Discrepancies were noted in approximately 10% of the kidneys, but main discrepancies, which would result in a different estimation of the quality of drainage, were only observed in 2% of the kidneys. There was no bias in the discordances; OE could reveal a better as well as a worse quality of drainage than NORA. It is likely therefore that imperfections of both parameters might be the cause of the divergences. The stratification of the kidneys according to age, overall renal function, split function, or quality of drainage did not modify the results. CONCLUSION: NORA, being much easier to program, can replace the output efficiency in the evaluation of renal drainage.

Can severely impaired cortical transit predict which children with pelvi-ureteric junction stenosis detected antenatally might benefit from pyeloplasty?

INTRODUCTION: Until recently, renogram, performed in children with pelvi-ureteric junction stenosis detected antenatally, has not been able to predict the probability of function improvement after surgery or the risk of function deterioration in case of conservative attitude. Recently, Schlotmann et al. have suggested that cortical transit might have this predictive role. The aim of this study, focused on those kidneys with severely impaired cortical transit, was to verify this statement. METHODS: All renograms performed in children during a 3-year period (n=729) were retrospectively reviewed and 19 pediatric patients were selected based on an antenatally detected unilateral pelvi-ureteric junction syndrome, the existence of at least two renograms during the follow-up and a severe cortical transit impairment, visually defined. Twenty-six pairs of data could be analyzed and allowed comparing preoperative and postoperative differential renal function (DRF), and the DRF changes during the conservative management. RESULTS: Among the 16 patients who underwent pyeloplasty, 10 showed a significant DRF improvement. Among the 10 patients with conservative follow-up, four showed a significant DRF deterioration. CONCLUSION: Severely impaired cortical transit seems to be a valuable marker of those patients who could benefit from a pyeloplasty, either because of the high probability of postoperative DRF improvement, or because of DRF deterioration in case of an conservative approach. However, a normal cortical transit, as defined in this study, does not exclude the risk of DRF deterioration. Alternatively, the design of this study does not allow excluding the fact that DRF might improve after pyeloplasty despite a normal cortical transit.

Normalized residual activity and output efficiency in case of early furosemide injection in children.

OBJECTIVE: Values for output efficiency (OE) and normalized residual activity (NORA) in paediatric patients have been published previously. However, it is now a usual practice to inject furosemide at the beginning of a renogram acquisition (F0 procedure). The aim was to evaluate OE and NORA obtained on F0 renograms, in normal and abnormal paediatric kidneys. METHODS: Three groups of kidneys were selected: group 1, normal kidneys (n=155); group 2, dilated but unobstructed kidneys (n=20); and group 3, hydronephrotic kidneys (n=84). A 20-min Tc-mercaptoacetyltriglycine renogram was obtained under early furosemide injection (F0) and was completed by late postmicturition (PM) images. OE and NORA were calculated at the end of the renogram and on the PM images. RESULTS: Group 1: NORA and OE calculated at the end of the F0 renogram revealed better drainage than without F0 stimulation. The PM parameters were comparable with those previously obtained after late furosemide injection (F+20). Group 2: the drainage, despite the early injection of furosemide, was often unsatisfactory at the end of the F0 renogram, but improved dramatically upon the PM acquisition. Group 3: almost normal values up to very abnormal ones were observed. In 35% of kidneys, the values of drainage were out of the range of group 2. CONCLUSION: Under early furosemide injection, renal drainage in the normal kidneys was better than in basic conditions. In dilated unobstructed kidneys, NORA and OE obtained on late images after micturition were, respectively, below 1.5 and above 80%.