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Biomedical subjects

R A Shields

Publications and source records attributed to R A Shields.

At least 37 records · Page 2Linked to original sources
PubMed1987

A comparison of technetium-99m-thiodiglycolic acid and iodine-123-hippuran in the evaluation of equivocal upper urinary tract obstruction.

In a comparative trial, 21 patients (mean age 43 (range 19-66) years) with dilated upper urinary tracts underwent diuresis renography with both 123I-hippuran and the experimental agent. 99Tcm-thiodiglycolic acid (TDG). Deconvolution analysis of the derived renograms was also performed and the transit times were calculated. Excellent agreement was found between results with the two radiopharmaceuticals. There was complete agreement in interpretation of the response to diuresis with both agents and 84% agreement in the transit time estimations. Good images were produced with both agents and 99Tcm-TDG is considered to be a useful alternative to 123I-hippuran.

Adult↗
PubMed1985

Nuclear medicine activity in the United Kingdom.

A survey of the extent of diagnostic and therapeutic nuclear medicine procedures in the UK has been conducted, and information collected on the types of imaging equipment employed and the typical activities of radiopharmaceuticals administered to patients. A total of 380,000 administrations took place in 1982, corresponding to approximately 6.8 per thousand head of population. 84% were imaging investigations, 13% were non-imaging diagnostic procedures and about 3% were for therapy. Bone scans accounted for 25% of all procedures and 99Tcm was the radionuclide of choice for 75% of investigations. Gamma cameras are superseding rectilinear scanners and most are being purchased together with dedicated image processing computers. Their average annual workload is 922 patients per year. There was considerable variation between the typical administered activities reported by different hospitals for the same procedure, and in some cases the figures reported exceeded the maximum usual activities recommended by the Administration of Radioactive Substances Advisory Committee.

Humans↗
PubMed1984

99Tcm-TDG renography with deconvolution analysis: a comparative study with 99Tcm-DTPA and 123I-hippuran.

TDG has been compared with hippuran and DTPA in normal subjects and the derived gamma camera renograms of both the whole kidney and parenchymal regions subjected to deconvolution analysis using the matrix algorithm. The transit time of TDG was found to be longer than both hippuran and DTPA. The parenchymal mean transit time of TDG was 3.0 +/- 0.6 min (mean +/- S.D.). That of hippuran was 2.2 +/- 0.7 min and DTPA, 2.6 +/- 0.5 min. It is thought that a small fraction of the TDG is bound to the renal parenchyma thus prolonging both the mean and maximum transit times.

Adult↗
PubMed1984

Ureteroureteric reflux. Pathological entity or physiological phenomenon?

The clinical, urographic and radionuclide examinations of 28 consecutive patients with incomplete duplication of the upper urinary tract are presented. Four possible types of urodynamic abnormality can occur in this condition and 3 of these were found in 8 of the 28 patients. The urodynamics of normal and duplex upper tracts are reviewed and the question of whether the abnormalities represent a pathological process requiring surgery or a harmless physiological variant is examined.

Adolescent↗
PubMed1984

Diuresis renography and parenchymal transit times in the assessment of renal pelvic dilatation.

A comparison has been made between the results of diuresis renography and deconvolution analysis of the renogram in 36 patients (46 kidneys) with urographically demonstrated renal pelvic dilatation. The mean transit times obtained by deconvolution analysis of the parenchymal renograms of eight normal volunteers had a mean value of 2.8 + 0.6 (S.D.) min, and the upper limit of normal was thus established as 4 min. Twenty-two of 29 kidneys (76%) with nonobstructive diuresis renograms had parenchymal mean transit times of 4 min or below. Fourteen out of 17 kidneys (82%) with obstructive diuresis renograms had parenchymal mean transit times above 4 min. Both investigations may contribute to the noninvasive assessment of dilated renal pelves; the parenchymal retention function (quantified by mean transit time) assesses the effects of dilatation on tubular transit and renal function, whereas the diuresis renogram is a more specific test for evaluating impedance to flow.

Diuresis↗
PubMed1981

The dilated non-obstructed renal pelvis.

This paper discusses 28 patients with renal pelvic dilatation in whom obstruction was excluded by excretion urography and diuresis renography. The clinical presentation and progress of the patients over a follow-up period of 1 to 5 years are presented. One patient required pyeloplasty, one developed 2 asymptomatic pelvic calculi and one showed some deterioration in function on the affected side. The remaining 25 patients remain well and their follow-up renograms show satisfactory renal function and excretion. Before the advent of objective means of assessing renal function and urodynamics, these patients would probably have been subjected to pyeloplasty. The present study confirms that the correct management of the dilated non-obstructed renal pelvis is conservative.

Adolescent↗
PubMed1981

Radionuclide studies of the lower urinary tract.

The results of prospective experimental and clinical studies into the use of radionuclides in the evaluation of urinary flow rates and residual urine volume estimations are presented. The results indicate that the radionuclide estimation of flow rates is accurate, but complex and time-consuming compared with other available methods. The calculation of residual urine is simple and accurate where residual volumes are not extremely large. The opportunity for such lower tract studies after renography should not be missed where clinically appropriate, and the combined upper and lower tract studies provide a useful quantitative urological profile.

Humans↗
PubMed1980

The plasma protein binding of HIDA.

By using Sephadex gel column chromatography to separate substances into their various components according to molecular weight, we have investigated the effect of incubating several "brands" of HIDA in plasma, in vitro. The results show that such incubation has no effect on either dimethyl HIDA, or diethyl HIDA, but that in the case of para-butyl HIDA, incubation in plasma increases the Rf value to that of HSA (human serum albumin). This indicates that para-butyl HIDA becomes bound to plasma proteins, in contrast to both dimethyl HIDA and diethyl HIDA.

Blood Proteins↗
PubMed1980

The preparation and composition of HIDA.

The compositions of four "brands" of Tc-HIDA-dimethyl HIDA (Sorin Biomedica), diethyl HIDA (Solco), diethyl HIDA (The Radiochemical Centre), and para-butyl HIDA (Sorin Biomedica)--were investigated at varying times after their preparation from "instant kits", by using Sephadex gel column chromatography. Up to three peaks of activity were seen in each chromatogram, representing free reduced technetium, the monocomplex, and the biscomplex of Tc-HIDA respectively. In all cases the free reduced technetium component diminished to reach a plateau at less than 4% of total activity, by 1 h. In both "brands" of diethyl HIDA there was a transformation from the monocomplex to the biscomplex which took about one hour. The rate of this transformation was increased by raising the temperature of incubation, or by agitation during incubation. In the para-butyl HIDA this transformation was again noted, but was incomplete. In the dimethyl HIDA the monocomplex form was not seen. There was no noticeable disintegration of any Tc-HIDA complex up to 6 h. It is suggested that HIDA should be incubated for 1 h after preparation, before use, to achieve a stable composition.

England↗
PubMed1980

Regional left ventricular wall motion from first-pass radionuclide angiocardiography using an Anger camera. Experimental and clinical study.

Experimental studies with a balloon phantom, and clinical studies were performed to evaluate first-pass radionuclide angiocardiography using a gamma camera in the assessment of regional wall motion. The phantom studies showed that choice of isocount contour was not critical in edge detection. Adequate count densities could be achieved, but only at the expense of temporal resolution. The clinical studies disclosed a good correlation with radiography in normal subjects and those with diffuse ventricular disease but a poor correlation in subjects with localised abnormalities of wall motion.

Cineangiography↗
PubMed1979

Study of right ventricular function in ischaemic heart disease using radionuclide angiocardiography.

A technique for the estimation of LVEF from first passage radionuclide angiocardiography was adapted to provide estimates of RVEF. In 17 subjects with no history of cardiovascular disease mean LVEF was 0.71 +/- 0.08 and mean RVEF 0.65 +/- 0.08. Mean values for 15 subjects with coronary artery disease but no previous history of myocardial infarction were 0.66 +/- 0.10 for LVEF and 0.65 +/- 0.08 for RVEF. Depressed ejection fractions were found after acute myocardial infarction. LVEF was lower after anterior (0.43 +/- 0.06) than inferior (0.51 +/- 0.10) infarction. RVEF was normal in the majority of subjects with anterior infarction (0.58 +/- 0.10) but was depressed after inferior infarction (0.50 +/- 0.05). Similar, although less marked, results were found in a group of subjects with old myocardial infarction.

Adult↗
PubMed1979

Idiopathic hydronephrosis--the diuresis renogram: a new non-invasive method of assessing equivocal pelvioureteral junction obstruction.

A new method to evaluate patients with equivocal obstruction of the pelvioureteral junction is described. It involves the performance of a standard 131iodine-hippuran renogram followed by a second renogram 3 minutes after an intravenous injection of the diuretic, frusemide. When the 2 results are inspected together it is found that the patients can be separated into 4 groups: 1) normal, 2) obstructed, 3) atonic and 4) partially obstructed. The results in 23 children and 27 adults with suspected obstruction of the pelvioureteral junction are presented. Obstruction was confirmed in 18 patients and excluded in 32. The correlation between the renogram results and clinical, radiological and operative findings is discussed. The technique is simple, accurate and non-invasive, and it is recommended after excretory urography before proceeding to more invasive tests.

Adult↗
PubMed1978

Intracellular electrolyte depletion in patients with ileostomies.

Fourteen apparently healthy patients with ileostomies were found to be depleted of total exchangeable sodium and potassium, but had normal serum electrolyte concentrations and normal extracellular fluid and total body water volumes. The low exchangeable sodium and potassiums were thus primarily due to depletion of the intracellular compartment. There was no evidence of renal or intestinal conservation of these ions and plasma aldosterone, renin activity, and prolactin concentrations were normal in most and only moderately raised in a few. This apparent lack of any hormonal compensatory change to the electrolyte depletion may be due to the normality of the extracellular fluid volume and electrolyte concentrations. These patients seem to have adapted to a stable but depleted intracellular sodium and potassium state.

Adult↗