Amnon Piepsz

Gastric emptying with gastro-oesophageal reflux.

The time taken for gastric emptying of a liquid (milk) or a semi-liquid (pudding) meal was evaluated in 477 infants and children. These patients were referred for suspected gastro-oesophageal reflux and underwent gastro-oesophageal scintigraphy, prolonged oesophageal pH study, manometric evaluation of the lower oesophageal sphincter pressure, and fibreoptic endoscopy. No difference in gastric emptying was observed in children aged under 3 years, regardless of the presence or absence of the gastro-oesophageal reflux, the pressure of the lower oesophageal sphincter, or the presence of oesophagitis. In children over 6 years, however, gastric emptying was significantly delayed in those presenting with reflux compared with those without reflux; in children over 3 years there was slower gastric emptying in those with a decreased lower oesophageal sphincter pressure compared with those with higher pressure and in those with overt oesophagitis compared with those without oesophagitis. This study suggests that gastro-oesophageal reflux is more severe in childhood than in infancy, probably due to more complex motor disorders affecting the gastric fundus as well as lower oesophageal sphincter function.

Evaluation of reflux episodes during simultaneous esophageal pH monitoring and gastroesophageal reflux scintigraphy in children.

Gastroesophageal pH monitoring and reflux scintigraphy were simultaneously performed in 65 children, who were being investigated for suspected gastroesophageal reflux disease. The aim of the study was to compare, peak per peak, the information provided by the two techniques during a 1-h simultaneous-recording period. During this period, 123 reflux episodes were recorded with both techniques, but only six occurred simultaneously. Significantly more reflux episodes were recorded on scintigraphy (n = 88; p less than 0.05), particularly during the first half-hour period (n = 62), if compared with the number of pH drops greater than 1 unit, even at pH levels higher than 4 (n = 41; p less than 0.05). It is concluded that the two techniques explore differently the reflux phenomenon.

Measurement of separate kidney clearance by means of 99mTc-DTPA complex and a scintillation camera

A new radioisotopic method of determining the separate glomerular clearance of the kidneys is described. After injection of 99mTc-DTPA, the data from a scintillation camera are recorded by computer. The renal curves are corrected for extrarenal activity and the plasma curve is obtained from a precordial curve. At each instant the slope of the renal curve divided by the corresponding plasma concentration gives the separate clearance value, in the period extending from 80 to 180 s after injection of the tracer. The error and correction factors introduced are discussed. Normal values are established on 25 patients and correspond to inulin clearance values. Left kidney: 60 ml/min (SD=13). Right kidney: 57 ml/min (SD=12). The method is simple for the patient, takes only 20 min, is not dangerous, is particularly applicable to young children and can be repeated frequently in the same patient.

A simple method for measuring separate glomerular filtration rate using a single injection of 99mTc-DTPA and the scintillation camera

A new technique for measuring glomerular filtration in each kidney has been developed using a scintillation camera and the 99mTc-DTPA complex. The technique has been applied to 101 children with various uropathies. Correlations with the total and separate creatinine clearance, the HgCl2 uptake test, and the maximal urinary concentration have been good. The reproducibility of the method has been satisfactory in a small number of patients. The test is particularly adapted to children because of its simplicity, reduced trauma, short duration (20 minutes) and low-radiation dose. In contrast to some other radioisotope techniques, it can be carried out in infants.

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; Chantlers 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.

NORA: a simple and reliable parameter for estimating renal output with or without frusemide challenge.

The aim of this study was to evaluate a simple parameter describing renal output, namely NORA (normalized residual activity). We first compared, in a simulated model, different parameters of transit to an ideal standard; we then compared, in a clinical study, NORA and output efficiency. 123I-hippurate, 99Tcm-DTPA and 99Tcm-MAG3 plasma curves, each with two levels of renal clearance, were convoluted by means of different types of simulated retention functions, with different mean transit times. On the reconstructed renograms, several parameters reflecting renal transit were determined and compared with mean transit time. In a second step, in 33 patients, we compared output efficiency and NORA (i.e. the residual renal activity), normalized by the renal activity at 2 min. These two parameters were calculated at the end of the renogram, at the end of the frusemide test and after the micturition phase. In the simulated model, both output efficiency and NORA were only slightly influenced by the level of overall renal function. In the clinical study, a good correlation was found between output efficiency and NORA, whatever part of the study considered (renogram, frusemide test, post-voiding image). NORA is a simple and reliable parameter that allows quantification of renal output; it is almost independent of the level of renal function and can be used whatever the timing of the frusemide injection.

Single photon emission computed tomography in seizure disorders.

Fourteen children with various seizure disorders were studied using a cerebral blood flow tracer, 123I iodoamphetamine (0.05 mCi/kg), and single photon emission computed tomography (SPECT). In the five patients with radiological lesions, SPECT showed congruent or more extensive abnormalities. Five of the nine children with a normal scan on computed tomography had abnormal SPECT studies consisting of focal hypoperfusion, diffuse hemispheric hypoperfusion, multifocal and bilateral hypoperfusion, or focal hyperperfusion. A focal lesion seen on SPECT has been found in children with tonic-clonic seizures suggesting secondarily generalised seizures. Moreover the pattern seen on SPECT seemed to be related to the clinical status. An extensive impairment found on SPECT was associated with a poor evolution in terms of intellectual performance and seizure frequency. Conversely all children with a normal result on SPECT had less than two seizures per year and normal neurological and intellectual development.

Consolidating the role of *I-MIBG-scintigraphy in childhood neuroblastoma: five years of clinical experience.

In recent years,*I-MIBG (*I-metaiodobenzylguanidine), which is transported and stored in the chromaffin cells, has been shown to allow good visualization of neuroblastomas in children. This paper deals with 30*I-MIBG-scans performed in 20 children: 16 with neuroblastoma, 3 with retinoblastoma, and 1 with a malignant paraganglioma. A high detection rate was found for both primary and secondary sites of neuroblastoma.*I-MIBG was generally superior to99mTc-MDP bone scintigraphy in the detection of bone metastases. Our experience illustrates the unique place of*I-MIBG-scintigraphy compared with other imaging techniques: it makes it possible to define the nature of the tumour, particularly in cases with normal catecholamine levels; to establish how extensive the lesions are at the time of diagnosis; and to confirm complete remission. No abnormal*I-MIBG uptake was noted in the 3 cases of retinoblastoma.

Low Serum Bone Gamma-Carboxyglutamic Acid Protein Concentrations in Patients with Cystic Fibrosis: Correlation with Hormonal Parameters and Bone Mineral Density

In 31 children and adolescents with cystic fibrosis (CF), whose bone mineral density (BMD) was determined at the level of the lumbar spine, serum bone gamma-carboxyglutamine acid (GLA) protein (BGP) was measured. A standard radioimmunoassay method gave for the studied CF population a median serum BGP concentration of 9 micrograms/l (range: 0.8-18.6) which corresponds to a median Z-score for age of -1.72 (range: -3.3 to +0.04). Thirteen patients presented a BGP concentration lower than 2 standard deviations (SD) under the mean for age. These patients did not differ from the others by their circulating thyroxine, triiodothyronine, 25-hydroxyvitamin D or parathyroid hormone levels. The lowering of the BGP concentration was neither related to the growth velocity nor to the severity of the lung disease, as assessed by lung scintigraphy. Six patients with a decreased BMD (< 2 SD under mean for age) were found. Five of them had also a decreased BGP concentration. In conclusion, decreased serum BGP concentration was found in 42% of the studied CF patients and could not be related to hormonal abnormalities. Serum BGP had a low specificity (72%) in predicting osteopenia in young CF patients.

Gastro-oesophageal scintiscanning in children

Abstract99mTc colloid scintigraphy is a sensitive technique for the detection of gastro-oesophageal reflux, compared to X-ray studies. A quantification index of reflux is used and can be of value when there is concern about the significance of a positive result. Continuous monitoring during one hour increases by 25% the detection of reflux in comparison with a 30 min test. In our series, no case of lung aspiration was recognized using this technique. The scintiscanning index cannot predict the existence of an associated oesophagitis.