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Biomedical subjects

A Piepsz

Publications and source records attributed to A Piepsz.

At least 55 records · Page 3Linked to original sources
PubMed1999

Consensus report on quality control of quantitative measurements of renal function obtained from the renogram: International Consensus Committee from the Scientific Committee of Radionuclides in Nephrourology.

Among all the physiological indices that can be quantified using renography, measurement of renal function is the most basic. These measurements are used to make critical clinical management decisions and, as such, their reliability needs to be quality assured. This article seeks to address each aspect of the renography procedure, with particular emphasis on the effect on measurement of relative renal function. Estimation of individual kidney function is mentioned, but only briefly. A consensus approach was adopted, overseen, and directed by a chairman appointed by the Scientific Committee of the International Radionuclides in Nephro-Urology Group. The chairman selected the panel of experts from eight different countries based on their practical experience in the field. Where evidence exists to support the various recommendations it is given. Otherwise, the stated guidance represents the considered opinion of a body of experts, based on long experience and unpublished data. Some necessary compromises were made to account for the fact that renography is seldom performed solely with the purpose of measuring relative renal function. The technicalities of renography have always been a source of debate in nuclear medicine, which is reflected by the fact that a consensus could simply not be reached on a small number of issues. The structure of the report ensures that these are clearly indicated. This should serve to highlight gaps in our current knowledge, thus helping to direct future research. It is envisaged that the recommendations will be revised on a 2-year cycle to ensure that they remain up to date. An "open" process will be used to encourage participation and ownership. It is hoped that promotion of these guidelines, suitably complemented by audit processes, will raise standards in the practice of gamma camera renography.

Adult↗
PubMed1999

Consensus on renal cortical scintigraphy in children with urinary tract infection. Scientific Committee of Radionuclides in Nephrourology.

A questionnaire related to cortical scintigraphy in children with urinary tract infection was submitted to 30 experts. A wide consensus was reached on several issues related to planar images: 99mTc dimercapto succinic acid (DMSA) appears as the most appropriate tracer for renal imaging; dynamic tracers are considered to be inferior, in particular 99mTc diethylenetriaminepentaacetate, which is not recommended. The general opinion is that DMSA scintigraphy is not feasible with a minimal dose below 15 MBq, whereas the maximum dose should not be higher than 110 MBq. The dose schedule generally is based on body surface area, and sedation is only exceptionally given to children. Images are obtained 2 to 3 hours after injection, preferably with high resolution collimators; pinhole images are used by only half of the experts. Posterior and posterior oblique views are used by most of the experts, and the posterior view is acquired in supine positions. At least 200.000 kcounts or 5 minute acquisition is required for nonzoomed images. As a quality control, experts check the presence of blurred or double outlines on the DMSA images. Color images are not used and experts report on film or directly on the computer screen. As far as normal DMSA images are concerned, most experts agree on several normal variants. Hydronephrosis is not a contraindication for DMSA scintigraphy but constitutes a pitfall. Differential renal function generally is measured, but no consensus is reached whether or not background should be subtracted. Most of the experts consider 45% as the lowest normal value. A consensus is reached on some scintigraphic aspects that are likely to improve and on some others that probably represent persistent sequelae. There is a wide consensus for the systematic use of DMSA scintigraphy for detection of renal sequelae, whereas only 58% of the experts are systematically performing this examination during the acute phase of infection.

Child↗
PubMed1999

Relative 99mTc-MAG3 renal uptake: reproducibility and accuracy.

UNLABELLED: The aim of this study was to estimate the reproducibility and accuracy of 99mTc-mercaptoacetyltriglycine (MAG3) relative percentage uptake. METHODS: Reproducibility was evaluated on healthy volunteers who were submitted twice to a 99mTc-MAG3 renographic study, which used different uptake algorithms, different background corrections and different time intervals. Accuracy was evaluated in a group of patients with symmetrical or asymmetrical relative renal function, who underwent both 99mTc-dimercaptosuccinic acid (DMSA) and 99mTc-MAG3 studies, using the DMSA relative percentage uptake as a reference. RESULTS AND CONCLUSION: The methods that combined the best reproducibility and accuracy for estimating 99mTc-MAG3 left-to-right uptake ratio were the integral method, with subrenal or perirenal background correction, and the Patlak-Rutland plot. The use of the integral method without background correction introduced a systematic bias, whereas the slope method resulted in high variability. Therefore these methods cannot be recommended.

Adult↗
PubMed1999

Bone scintigraphy in children with persistent pain in an extremity, suggesting algoneurodystrophy.

In this retrospective study, the data of bone scintigraphy performed in 21 children suspected of reflex sympathetic dystrophy (RSD) were analyzed. All of them had persistent pain in an extremity or a clinical suspicion of RSD. All children with strong suspicion of RSD showed diffuse hypoactivity at the level of the involved area on bone scintigraphy. This hypoactivity was clearly related to a decreased vascular supply. The specificity of this scintigraphic pattern is questionable, however, since two children without suggestive clinical signs for RSD had the same scintigraphic pattern.

Arm↗
PubMed1999

Overall and single-kidney clearance in children with urinary tract infection and damaged kidneys.

UNLABELLED: The overall and single-kidney clearance in children with acute urinary tract infection was investigated retrospectively using the combination of the relative 99mTc-dimercaptosuccinic acid (DMSA) uptake and the 51Cr-ethylenediaminetetraacetic acid clearance. METHODS: There were 180 patients with both normal kidneys, 56 with clear unilateral abnormalities on DMSA scintigraphy and 11 with two abnormal kidneys. Half of the patients were younger than 2 y, and because of the progressive maturation of the renal function, they were not considered in the analysis of the absolute overall and single-kidney clearance; nevertheless, they were included in the analysis of the relative DMSA percentage uptake. RESULTS: When only one kidney was affected on DMSA scintigraphy, the clearance of the affected kidney was lower than on the normal side and often abnormally low. In these unilaterally affected kidneys, contralateral compensation mechanisms tended to occur, resulting in preservation of overall clearance. This compensation was probably not present only on the contralateral side. On the abnormal side, the clearance was normal in about half of the cases, probably because of intrarenal compensation occurring in regions not damaged by the infection. In addition to these compensation mechanisms, hyperfiltration was probably present in many cases of acute urinary tract infection with intact or unilaterally damaged kidneys.

Acute Disease↗
PubMed1998

Left ventricular perfusion deficit in patients with cystic fibrosis.

Left ventricular failure is not considered an important feature in cystic fibrosis (CF), but abnormalities of left ventricular function have been reported. Except for a few cases of heart failure in neonates with CF, there is no evidence of a primary disorder of the myocardium in patients with CF. Since left ventricular perfusion disturbances can cause left ventricular dysfunction, we decided to investigate left ventricular perfusion during exercise using sestamibi-Tc-99m-labeled macroaggregates. Eighteen CF patients with varying degrees of disease severity participated in the study. They underwent a thorough clinical evaluation, lung perfusion scan, pulmonary function testing, echocardiography, transcutaneous measurement of oxygen saturation at rest and during exercise, and an exercise test with injection of sestamibi-Tc-99m-labeled macroaggregates at peak exercise. Six patients (33%) showed abnormalities of the myocardial distribution of sestamibi-Tc-99m-labeled macroaggregates during exercise. Scanning abnormalities correlated with the clinical score, mean maximum expiratory flow at 50% of vital capacity (MEF50), and arterial oxygen desaturation during exercise. We conclude that deficits in left ventricular uptake of sestamibi-Tc-99m-labeled macroaggregates during exercise seem common in patients with severe CF lung disease. The cause of these deficits is not fully understood, but the occurrence seems to be associated with a poor prognosis.

Adult↗
PubMed1998

Technetium-99m mercaptoacetyltriglycine clearance values in children with minimal renal disease: can a normal range be determined?

Use of technetium-99m labelled mercaptoacetyltriglycine (99mTc-MAG3) simplifies and improves the quantification of renal clearance in children by virtue of its permanent availability, good imaging properties and low radiation exposure. Due to the lack of reference values for 99mTc-MAG3 clearance in children, the Paediatric Task Group of the EANM initiated a multicentre study to evaluate 99mTc-MAG3 clearance values in children with minimal renal disease. One hundred and twenty-five children aged between 12 months and 17 years, classified as renally healthy using defined diagnostic criteria, were included in the study. 99mTc-MAG3 clearance was calculated using an algorithm on the basis of a single blood sample taken at any time between 30 and 40 min after tracer injection. In addition, the absolute 99m-Tc-MAG3 clearance values were normalized to body surface area. For further evaluation the children were classified into several groups according to age. There was a continuous increase in non-corrected 99mTc-MAG3 clearance values from the age of 1 year up to the age of 17 years (mean value <2 years: 98+/-57 ml/min; mean value >8 years: 208+/-66 ml/min). Normal clearance values for adults were achieved by the age of 8 years. Analysis of the relationship between non-corrected clearance and age yielded a correlation coefficient of r=0.7. When these absolute clearance values were normalized to body surface area, we found nearly constant clearance values for all age groups, with a mean clearance value of 315+/-114 ml/minx1.73 m2. The correlation coefficient for the relationship between normalized clearance and age was r=0.28. In conclusion, the clearance of 99mTc-MAG3 increases continuously throughout childhood into adolescence due to the maturation and growth of the kidney. After normalization of the absolute clearance to body surface area, no correlation between clearance and age could be proven.

Child↗
PubMed1998

Five-year study of medical or surgical treatment in children with severe vesico-ureteral reflux dimercaptosuccinic acid findings. International Reflux Study Group in Europe.

UNLABELLED: The results of serial dimercaptosuccinic acid (DMSA) imaging over 5 years are reported in 287 children with severe vesico-ureteral reflux entered into the European Branch of the International Reflux Study in Children. The children were randomly allocated to medical (n=147) or surgical (n=140) management and DMSA studies were performed during the follow up period at least 6 months after any urinary tract infection. Abnormal images were classified into four types: (1) large polar hypodensity with normal renal outline; (2) peripheral photon deficient defect(s) in a non-deformed kidney; (3) small renal image with normal contour; and (4) peripheral defect(s) with resultant irregularity of the renal outline. The DMSA findings were abnormal at entry in 235 (82%) with no difference in incidence or severity between the two treatment groups. During follow up, deterioration was observed in 25 medically and 23 surgically treated patients and comprised image deterioration alone in 17, image deterioration with corresponding reduction in differential function in 16 and reduction in relative function without image change in 15, with similar distribution between the two treatment groups. Deterioration was more frequent in children entering the study under the age of 2 years and in those with grade IV rather than grade III reflux. These findings, showing no difference in outcome between children managed surgically or medically, are consistent with the radiological results already published. CONCLUSION: In the International Reflux Study the DMSA scintigraphic data showed no difference in outcome between children managed surgically or medically.

Child↗
PubMed1998

Technetium-99m-dimercaptosuccinic acid renal scintigraphy in children over 5 years.

We retrospectively evaluated the frequency of renal scintigraphic abnormalities in children over 5 years admitted with a first symptomatic urinary tract infection (UTI). Among 261 children investigated, we found only 23 over 5 years having had technetium-99m-dimercaptosuccinic acid scintigraphy during the acute phase of a first UTI. Obvious scintigraphic abnormalities were detected in 14 children (15 kidneys): 12 kidneys showed focal cortical defects and 3 were small and deformed. Ultrasound was normal in 7 of the 15 kidneys with abnormal scintigraphy and in all the kidneys with normal scintigraphy. Among the 12 kidneys with focal cortical lesions, 8 kidneys returned to normal or improved considerably 2-12 months after initial work-up. In conclusion, in children over 5 years admitted with a first symptomatic UTI, the frequency of scintigraphic abnormalities is high and a strategy based only on ultrasound data would miss about 50% of the abnormal kidneys.

Acute Disease↗
PubMed1997

How good is the slope of the second exponential for estimating 51Cr-EDTA renal clearance?

The aim of this study was to test the reproducibility of the second exponential of the plasma disappearance curve of 51Cr-EDTA and to compare it with the single slope-intercept method. The test was performed twice among 24 young healthy volunteers at an interval of 8 days and under similar physiological conditions. After the intravenous injection of 3.7 MBq of 51Cr-EDTA, four blood samples were taken between 1.5 and 4 h and combinations of two, three or all four of these were used to calculate the slope of the plasma clearance curve. The clearances rates were calculated using these slopes and the corresponding intercepts of the slopes with the y-axis. The standard deviation of the differences between the first and the second measurements was between 8 and 10% for the different clearance estimates, and between 11 and 17% for the different slope estimates, reflecting the wider variability of the slope estimate. Using the first series of measurements, the change of timing for blood sampling introduced a wider variability for the slope estimate than for the clearance estimate.

Adult↗