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Biomedical subjects

A Piepsz

Publications and source records attributed to A Piepsz.

At least 73 records · Page 4Linked to original sources
PubMed1997

Pediatric nuclear medicine: a practical approach.

This paper is devoted to the practical aspects of pediatric nuclear medicine, particularly the controversy about drug sedation. The authors conclude that drug sedation should be exceptionally used. There is an alternative way, consisting in an adequate approach of the patient: good information to the parents and the child; taking care of the child's environment, starting from the first contacts in the waiting room; specific education of technologists: this includes injections and blood sampling, but also proper handling of the child during the procedure and adequate psychological attitudes toward child and parents. Taking these factors into account, it is exceptional that a test has to be postponed because of the lack of collaboration of the patient; good quality images, using the recommended paediatric amounts of radioactivity can be achieved even for procedures of prolonged duration.

Adolescent↗
PubMed1996

Oesophageal motility disorders in patients with psychiatric disease.

Clinical and experimental observations indicate that the motility of the oesophagus may be affected by emotional stimuli. The aim of this study was to evaluate the incidence of oesophageal contractility impairment in patients suffering from a psychiatric disorder. Fifty-one patients admitted to the psychiatric department were submitted to an oesophageal transit study by means of krypton-81m. All patients with an abnormal oesophageal transit underwent manometry and endoscopy. The level of depression and anxiety was evaluated by the treating psychiatrist, using the Hamilton Depression and Anxiety Rating Scales. The oesophageal transit was abnormal in 13 patients. Two of these 13 patients refused manometric investigation. In ten of the 11 remaining patients, the manometry revealed functional motor abnormalities. Endoscopy, performed in all these ten patients, was normal. In conclusion, a high percentage of oesophageal contractility disturbances was found in psychiatric patients complaining of anxiety and/or depression. These abnormalities were detected by scintigraphy as well as by manometry. Owing to the normal endoscopic findings, these contraction abnormalities are likely to reflect a functional motor impairment.

Anxiety↗
PubMed1996

Reproducibility of technetium-99m mercaptoacetyltriglycine clearance.

The aim of this paper was to determine the reproducibility (precision) of technetium-99m mercaptoacetyltriglycine (MAG3) clearance and to compare it with that of chromium-51 ethylenediamine tetra-acetic acid (EDTA). Twelve young volunteers (aged between 21 and 34 years), without any history of medical problems, were enrolled in this study. The test was performed twice, at an interval of 8 days and under similar physiological conditions. After the intravenous injection of both tracers, 15 blood samples were taken between 3 and 240 min. A biexponential fit was adapted to the plasma disappearance curves (5- to 120-min samples for 99mTc-MAG3 and 10- to 240-min samples for 51Cr-EDTA); the clearances were calculated according to Sapirstein and corrected for body surface area. The mean clearance values were 110 (range 85-130) and 226 (range 109-319)ml/min/1.73 m2, respectively, for 51Cr-EDTA and 99mTc-MAG3. For 51Cr-EDTA clearance, the mean difference between the first and the second measurement was -2.1% of the mean of the two successive values (SD: 8.4%). In ten cases, the difference was less than 12%; in two cases, the differences were 15% and 18%, respectively. For 99mTc-MAG3 clearance, the mean difference between the first and the second measurement was -20% of the mean of the two successive values (SD: 25%). In six cases, the difference was less than 12%; in four cases, between 15% and 40%; and in two cases, more than 60%. Methodological factors (impurities contained in the commercial kit, variable protein binding) as well as physiological factors (pH of urine, sodium load, stress) may explain the lack of precision of the 99mTc-MAG3 clearance. It is concluded that changes in 99mTc-MAG3 plasma clearance should be interpreted with care in daily routine.

Adult↗
PubMed1996

The robustness of the Patlak-Rutland slope for the determination of split renal function.

The aim of this study was to evaluate the variability of the Patlak-Rutland slope as applied to the renal clearance method. We analysed the 99Tcm-mercaptoacetyltriglycine renograms of 17 non-selected patients (both children and adults, number of kidneys = 34) with a single kidney glomerular filtration rate of 6-73 ml min-1 1.73 m-2. the acquisition time for the renograms was 20 min with a frame duration of 20 s. First, correction for background activity was introduced using the perirenal area and the size ratio between the kidney and the perirenal area. The Patlak plot was then applied. The first two points were systematically rejected and a series of linear fits calculated from the experimental points, starting from the third point (i.e. 1 min). The final point of the fit never exceeded the time of the peak of the renogram minus one minute (Tmax - 1) and was always less than 5 min. Although simple visual inspection of the slopes would suggest that the experimental points were distributed accurately along a straight line, it appeared that the slope was strongly dependent on the number of points used for the determination of the fit. As a second step, we restricted the number of points for fitting to the time interval between 1 min and 2 min 40 s. This procedure appeared to show that the Patlak methodology is reliable, giving rise to only small variations in slope, depending on the number of points chosen. However, even in this narrow time interval, significant errors can be made, either because of the very early escape of the radionuclide or because of statistical noise (e.g. in renal failure the signal-to-noise ratio is unfavourable). Therefore, it is advisable, when using this methodology, to restrict the fitting procedure to the second minute of the study and to check visually that this fixed time interval gives rise to a slope that is well adapted to the Patlak plot.

Adult↗
PubMed1996

Reproducibility of simplified techniques for the measurement of 51Cr-EDTA clearance.

The aim of this study was to assess the reproducibility of a number of simplified clearance methods using chromium-51 ethylenediamine tetraacetic acid (51Cr-EDTA) and to compare these with the multiple blood sample technique. Twenty-four healthy volunteers were enrolled into the study. The test was performed twice, 1 week apart and under similar physiological conditions. After intravenous injection of the tracer, 13 blood samples were taken between 5 and 240 min. The reference clearance was calculated after adapting a bi-exponential fit on the whole plasma disappearance curve. Simplified methods included the slope intercept method using different combinations of blood samples (2 and 4 h; 2, 3 and 4 h; 1.5, 2, 3 and 4 h; 1.5, 2 and 3 h) and several single clearance methods (Constable 3 h; Groth 3 h; Groth 4 h). The standard deviation of the differences between the first and second measurements were similar for all methods, confirming the comparable reproducibility of these methods.

Chromium Radioisotopes↗
PubMed1996

Overall accuracy of technetium-99m-MAG3 clearance measurements obtained with a gamma camera heart curve.

UNLABELLED: The aim of the present study was to evaluate the accuracy of 99mTc-MAG3 clearance measurements using a precordial gamma camera curve calibrated by a single plasma sample. METHODS: Technetium-99m-MAG3 was administered to ten young normal volunteers. A 60-min gamma camera acquisition was performed. Five different segments of the gamma camera curve were determined: 3 min to 20 min, 3 min to 30 min, 3 min to 40 min, 3 min to 50 min and 3 min to 60 min. A biexponential function was fitted on each of these five different segments, which were thereafter calibrated using eight different blood samples. These blood samples were successively used for calibration at 5, 10, 15, 20, 30, 40, 50 and 60 min. The single injection, multiple plasma sample method was used as reference. RESULTS: Camera clearances varied markedly based on the length of the precordial curve and on the time of the calibration sample. Different regression equations were obtained for each duration of the camera curve, and for each blood sample timing. Correlation coefficients were > 0.95 in most cases recording period of at least 50 min, however, was necessary to obtain a s.e.e. better than those obtained using a single blood sample method without gamma camera curve. CONCLUSION: The 99mTc-MAG3 clearance determination using a gamma camera heart curve calibrated with a single blood sample does not necessarily improve the accuracy of the one blood sample method.

Adult↗
PubMed1996

Renal technetium-99m-DMSA SPECT in normal volunteers.

UNLABELLED: Dimercaptosuccinic acid (DMSA) renal scintigraphy today is considered a sensitive and useful technique for the detection of cortical abnormalities. Recent studies have suggested that lesion detection can be improved by SPECT imaging. This study investigated normal kidneys using different SPECT modalities. METHODS: Ten young, healthy volunteers with normal clinical history and normal renal ultrasound underwent planar and SPECT DMSA imaging 2 to 4 hr after intravenous injection of 99mTc-DMSA (185 MBq). Analysis of SPECT data was focused on the homogeneity of cortical uptake (comparison of upper and lower pole activity) as well as on the presence or absence of focal cortical defects. RESULTS: No abnormality could be observed on the planar images. SPECT revealed, in seven kidneys (five left and two right), the presence of a hypoactive upper pole. This was visually observed on the coronal slices with up to 35% difference between upper and lower pole. Moreover, three focal cortical defects were visualized on the coronal slices as well as on three-dimensional surface shade displays. CONCLUSION: These normal patterns should be recognized when evaluating a patient with possible renal involvement.

Adult↗
PubMed1996

Feasibility of estimating glomerular filtration rate in children using single-sample adult technique.

UNLABELLED: This work was undertaken to verify whether a single-sample adult technique, when applied using body surface-corrected plasma concentration, can be used in place of specific pediatric method to estimate 51Cr-EDTA renal clearance in children. METHODS: In a series of 90 children (aged 0.1 to 15 yr). 51Cr-EDTA renal clearance was calculated using for different approaches. The first approach used specific pediatric single-sample methods; three techniques were chosen and they all used 120-min plasma concentration. The second approach used the same three specific pediatric methods, but they were applied using 120-min plasma concentration prescaled for 1.73 m2 body surface area. The third approach used single-sample methods designed for adults; three methods were again chosen. They all used 240-min plasma concentration. The fourth approach used the same adults algorithms, but they were applied using 240-min plasma concentration prescaled for 1.73 m2 body surface area. RESULTS: Clearances calculated using the three specific pediatric methods were all closely cross-correlated regardless of whether or not the plasma concentration was prescaled. The use of classical adult methods produced in some cases obviously erroneous clearance values. Improvements were observed when the same adult methods were applied using prescaled plasma concentration. Nonetheless, the clearance values obtained only fairly correlated with those obtained using specific pediatric methods. CONCLUSION: The single-sample adult technique using plasma concentration prescaled for 1.73 m2 body surface area cannot be used in place of a specific pediatric single-sample method to estimate 51Cr-EDTA renal clearance in children.

Adolescent↗
PubMed1996

Report of the Radionuclides in Nephrourology Committee on renal clearance.

The need for simple and accurate methods to measure renal function is self-evident. This need increases as techniques for intervention become available. The demand for evaluation of individual kidney function has increased with its role in the diagnosis and follow-up of unilateral renal disease and in decision making for conservative or surgical treatment based on residual renal function. The role of nuclear medicine in this area has been inhibited by confusion about conflicting methodologies. This report is meant to provide guidance to those centers that would like to initiate clearance procedures but have difficulty in choosing appropriate methodology.

Glomerular Filtration Rate↗
PubMed1996

99Tcm-DMSA renal scintigraphy for acute pyelonephritis in adults: planar and/or SPET imaging?

A number of authors have indicated a more sensitive detection of renal cortical defects using single photon emission tomography (SPET) compared with planar imaging when performing 99Tcm-dimer-captosuccinic acid (99Tcm-DMSA) renal scintigraphy. The place of SPET in the evaluation of kidneys in adults suspected of acute pyelonephritis (APN) remains controversial, however. The aim of this study was to address the role of SPET in adult patients suspected of having APN. Planar and SPET 99Tcm-DMSA renal imaging was performed in 53 patients. The data sets were separated and presented in random order to three independent observers. The kidneys were divided into three segments, which were classified as normal, definitely abnormal or equivocal. Ir. a second step, the number of lesions (definite or equivocal) on planar and SPET imaging were counted. The overall concordance between the planar and SPET imaging scores was 90.9, 89.9 and 87.7% for the three observers, respectively. Inter-observer discordance was recorded in a small percentage of both planar and SPET images. The number of lesions, based on the average of the three observers, was 22 for planar and 25 for SPET imaging. Obvious differences between observers were noted. The planar images were more often interpreted as equivocal by the least experienced observer. The more experienced observers gained limited additional information using SPET routinely. Most equivocal lesions on the planar scintigrams were observed in the lower segment. For SPET, no such distribution was noted. High-quality 99Tcm-DMSA images allow the detection of the same number of lesions as SPET in adults suspected of APN.

Acute Disease↗
PubMed1995

Recent advances in pediatric nuclear medicine.

This review is devoted to some controversial topics in the field of pediatric nuclear medicine. In most cases, drug sedation can be avoided and the nuclear medicine procedure can be successfully achieved simply by taking the emotional life of the child into account. Factors such as past negative experiences (painful procedures, hospitalizations), unfamiliar environment (frightening examination room), physical aggressions related to the nuclear medicine procedure (intravenous injections, cystography), and the feeling of loss of parents' protection all contribute to the child's anxiety. People in charge of pediatric procedures should be adequately trained to be aware of these factors and to create the best environmental conditions to avoid unnecessarily frightening the child. Methods for measuring renal clearance in children are numerous. It is my aim to review the different methods proposed in the literature, including the nonradioisotopic methods, the reference radioisotopic methods, the various simplified algorithms using blood samples, and the gamma-camera methods. Gastroesophageal reflux scintigraphy is a well-established procedure for the detection of gastro-esophageal reflux in children. However, despite the numerous advantages of this technique, it has not gained wide acceptance in the field of pediatric gastroenterology. This review focuses mainly on the comparison between scintigraphy and pH metry. Finally, the applications of 99m technetium-hexamethylpropylenamine brain single photon emission computer tomography in the field of pediatric neurology are still under development; this part of the review is an attempt to summarize the real contribution of this technique.

Brain↗
PubMed1995

Endoscopic submucosal Teflon injection (STING): an alternative treatment of vesicoureteric reflux in children.

The authors present their results in treating vesicoureteric reflux with an endoscopic submucosal teflon injection (STING) of the refluxing ureter. One hundred refluxing units in 68 children were treated with a maximum follow-up of five years. Indications were high grade reflux (III-V), persistence or progression of reflux despite conservative therapy, breakthrough urinary infections despite antibiotic prophylaxis and finally bad antibiotic compliance. Treatment was performed on an outpatient basis and appeared to be free of complications. Reflux was cured with a success rate of 75% after a single injection and 96% after two injections. With respect to the grade of reflux, best results were obtained in low grade reflux (Grade I-II). A 60-70% success rate was obtained in high grade reflux (III-V). The main advantage over open reimplantations lies in its non invasiveness, simplicity and possibility of being repeated in case of failure.

Child↗
PubMed1994

Estimation of normal chromium-51 ethylene diamine tetra-acetic acid clearance in children.

In order to estimate the normal range of chromium-51 ethylene diamine tetra-acetic acid (EDTA) clearance in children, we selected a series of 256 patients with past or present urinary tract infection who showed, at the time of the clearance determination, normal technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy and normal left to right DMSA relative uptake. The clearance was calculated by means of either the simplified second exponential method or the 120-min single blood sample; Chantler's correction was used in order to correct for having neglected the first exponential. There was a progressive increase in clearance from the first weeks of life (mean value around 1 month: 55 ml/min/1.73 m2), with a plateau at around 18 months. Between 2 and 17 years of age, the clearance values remained constant, with a mean value of 114 ml/min/1.73 m2 (SD: 24 ml/min); this is similar to the level described for inulin clearance. No significant differences were observed between boys and girls, or between clearance values calculated with one or with two blood samples. Taking into account the hour of intravenous injection of the tracer, we did not observe any influence of the lunchtime meal on the distribution of the 51Cr-EDTA clearance values.

Adolescent↗
PubMed1994

How good is technetium-99m mercaptoacetyltriglycine indirect cystography?

The aim of the present study was to estimate the sensitivity of indirect radionuclide cystography (IRC) performed with technetium-99m mercaptoacetyl-triglycine (MAG3), in comparison with the micturition cystourethrography (MCUG) and direct radionuclide cystography (DRC), for the diagnosis of vesicoureteric reflux. Two groups of patients were selected: group I comprised 40 children who underwent IRC during the acute phase of urinary tract infection and an MCUG 6 weeks later; group II comprised 42 (other) children with known reflux, who underwent IRC and DRC during follow-up. Taking as the reference the total number of refluxing kidneys detected by means of any cystographic technique, 99mTc-MAG3 ICR missed two-thirds of the refluxing kidneys. Most of the small refluxes were missed, but so too were 50% of the major refluxes. Taking as the reference 99mTc dimercaptosuccinic acid (DMSA) scintigraphy, MCUG detected 91% of the patients with DMSA abnormalities on at least one kidney, DRC detected 95%, and IRC detected 46% and 43% respectively, in groups I and II. The use of 99mTc-MAG3 IRC as the sole technique for the detection of vesicoureteric reflux gives rise to an unacceptable number of false-negative results.

Adolescent↗
PubMed1994

Effect of hyperfiltration on long-term follow-up of glomerular filtration rate in male Wistar rats.

It has been suggested that a prolonged course of hyperfiltration could lead to progressive deterioration of renal function. In order to test this hypothesis, the following protocol was applied to 60 male Wistar rats. At 12 weeks of life, the rats were submitted to a surgical procedure: sham operation (25 rats), unilateral nephrectomy (25 rats) or 3/4 nephrectomy (10 rats). The three groups were again divided into two subgroups: one with high-protein intake (36%) and one with a low-protein intake (12%). In order to avoid any additional traumatic procedure which could shorten the animal's life, the glomerular filtration rate (GFR) was measured without blood sampling, using a previously validated technique based on an image recorded by a gamma camera between the 9th and the 10th min after intravenous injection of 99m technetium diethylenetriaminepentaacetate (DPTA). The sum of both kidneys and bladder activity was expressed as a percentage of the injected dose. The test was performed before surgery and every month thereafter. Six weeks after surgery, the highest filtration rate was found in the rats with "two kidneys/high-protein diet", followed by the "two kidneys/low-protein diet", the "one kidney/high-protein diet", the "one kidney/low-protein diet" and the "1/2 kidney". The overall GFR in the one kidney/high-protein diet rat and in the 1/2 kidney rat was respectively 80% and 55% of the pre-operative values. Until 109 weeks of age, the survival rate was comparable in the five groups of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Improving the accuracy of 99Tcm-mercaptoacetyltriglycine clearance by using two blood samples instead of one? Paediatric Task Group of the EANM.

From a database of 133 patients (98 children and 35 adults) who underwent multiple blood sampling for 99Tcm-mercaptoacetyltriglycine (MAG3) clearance, we determined simplified algorithms allowing the estimation of clearance. A one-compartment model with two blood samples was applied. The best choices for the adult population were the 12 and 90 min blood samples, giving a standard error of the estimate (S.E.E.) of less than 10 ml min-1 1.73 m-2; for the children, the 10 and 80 min blood samples gave a S.E.E. of 20 ml min-1 1.73 m-2; for both the adults and the children, the 10 and 70 min blood samples gave the best results with, however, a S.E.E. of 19 ml min-1 1.73 m-2. The use of such a combined algorithm will therefore result in a degradation of the results in adults, suggesting that a separate algorithm for each group is preferable. We compared the accuracy of the two blood sample method to the one blood sample method based on previously published algorithms for children and adults, respectively. The S.E.E. was significantly lower, in adults as well as in children, using the empirical two blood sample method. This two blood sample method seems potentially useful for routine practice in adult patients. The advantages of using such a method in children is balanced by the practical problems inherent in the need to take a second blood sample during the first 10 min, at a time when the plasma activity is rapidly decreasing.

Adult↗
PubMed1994

Paediatric nuclear medicine procedures: routine sedation or management of anxiety?

In our department, examinations of long duration are performed without sedation. It is exceptional that a test has to be postponed because of lack of cooperation by the patient. Good quality images, taking into account the recommended paediatric amounts of radioactivity, are achieved for procedures such as MIBG whole body scanning (10 min frame-1), gastro-oesophageal reflux studies (60 min acquisition), renography and furosemide challenge (45 min) or pinhole views for bone or renal DMSA studies (20-30 min). While drug sedation remains in some conditions the only way to obtain a satisfactory nuclear medicine examination in children, we still believe that in most cases this can be achieved by taking the emotional life of the child into account. For that purpose, people in charge of the paediatric procedure have to be adequately trained.

Anxiety↗