Biomedical subjects
Publications and source records attributed to J F Klopper.
It is shown that during quantitative gastric scintigraphy with Tc-99m pertechnetate significant errors may occur if kidney uptake is ignored. The magnitude of the error was assessed in 12 patients, and could lead to an over-estimation of gastric uptake by up to 20%.
Two cases of chronic renal failure showing very interesting technetium-99m-pyrophosphate bone scans are presented. In both cases striking uptake of activity was shown in the left ventricle of the heart, the mucosa of the stomach and in both lungs. This picture was attributed to metastatic calcification in these organs. Cases of metastatic calcification demonstrated with bone-seeking agents have been presented previously, but have mainly shown intense uptake of activity in the lungs and in a few cases, and to a lesser degree, in the stomach. However, we believe that our cases are unique in showing especially the left ventricle of the heart as well as the mucosa of th stomach with exceptional clarity.
During a 2-year study period it was found that krypton-81m was useful in routine clinical practice. During this period 1563 technetium-99m perfusion studies and 807 krypton-81m ventilation studies were performed. A distinct advantage of krypton-81m was the ease with which multiple views could be obtained. These views could be directly compared with those of preceding perfusion studies. However, interruptions in the regular supply of rubidium-81/krypton-81m generators affected 17,1% of perfusion studies and xenon-127 should be a suitable substitute for these periods.
Uptake of gallium-67 in the chest is a relatively nonspecific indicator of active disease. In patients with suspected sarcoidosis a specific diagnosis can often be made if the head and neck are included during imaging. Seventy-five per cent of patients with sarcoid lesions in the lungs and mediastinum show uptake of the isotope in the salivary glands. If, in addition, the lacrimal glands concentrate the gallium, a diagnosis of sarcoidosis may be made with confidence. A case of mediastinal sarcoidosis, illustrating uptake of gallium-67 in the parotid and lacrimal glands, is discussed.
The volume of air trapped (Vat) in alveoli subtended by airways closed at residual volume (RV) was correlated with the volume of air left in the lungs at the start of airway closure (CC) in a clinical study of 13 patients with a variety of pulmonary disorders and 5 normal subjects. Vat was quantitated at RV from the in vivo distribution differences between 127Xe inspired as a bolus and again after equilibrium; CC was measured from the inflection point on the single-breath washout curve at the onset of phase IV. 127Xe activity was measured with a scintillation camera, and activity profiles were obtained for 28-45 consecutive 6.5-mm horizontal lung slices between base and apex. Three well-defined regions were found: A, in the upper lung, all of whose airways remained completely open; B, located above the base and containing both open and closed airways; and C, above the base, all of whose airways were closed. Of the Vat of 0.43 liter for the normals, 41% was located in region C. For the patients, the values were 59% of 0.59 liter. The relationship between the onset of phase IV and regional airway closure was confirmed for normals as well as patients. A statistically significant increase in closure was found for the patients over the normals. Excellent agreement was obtained between Vat/TLC (total lung capacity) and CC/TLC (r = 0.79, P less than 0.001) for normals as well as patients, and CC appears to reflect regional airway closure in both health and disease. Similar excellent agreement was obtained for the normals between lung height with closed airways and CC/TLC (r = 0.88, P less than 0.001). Vat appears to be the most important physiological determinant of phase IV, the value at RV representing the limiting case.
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A comparison of Tc-99m-labeled human serum albumin (HSA) and in vitro labeled red blood cells (RBC) was carried out in five subjects. The disappearance of radioactivity from the blood was more rapid for HSA (T 1/2, 281.6 minutes, range 202.1--318.3) than for RBC (T 1/2, 1719.8 minutes, range 767.6--5059.5). Urinary excretion was twice as great for HSA. Ratios of activity in heart blood pool to lung and liver were considerably greater for RBC up to 2 hours after administration. The results indicate that labeled RBC are superior to labeled HSA for blood pool imaging.
Although the ECG-gated radionuclide blood pool scan (GBPS) has become an established method for studying regional myocardial wall motion, it is usually performed with the aid of an expensive computer system. A simple, inexpensive method was developed to view gated radionuclide blood images by a film loop and a photographic motion detection (PHOMOT) technique. These techniques were compared with left ventricular cine angiography in 15 patients. Segmental wall movement (78 segments) showed identical results in 92% of cases. In all patients the same diagnosis was arrived at by GBPS and cine angiography. The photographic techniques developed offer a simple screening procedure to reduce cardiac catheterization in patients with suspected abnormalities of left ventricular wall contraction.
A study was carried out to determine if rooibos tea (Aspalathus linearis) has a deleterious effect on iron absorption similar to that of ordinary tea (Camellia sinensis). Three groups of volunteers, each consisting of 10 healthy young men comparable with regard to iron status and body dimensions, were studied. After ingestion of 1 muCi 59Fe and 16 mg of elemental iron, group A drank rooibos tea, group B ordinary tea and group C boiled water. Iron absorption was measured 14 days later with a whole body counter. Mean iron absorption after ingestion of rooibos tea, ordinary tea, and water was 7,25%, 1,70% and 9,34% respectively. In contrast to ordinary tea (P less than 0,0001), rooibos tea did not affect iron absorption significantly. The ascorbic acid content of rooibos tea varies between 121,8 and 154,9 mumol/l, depending on the method of preparation. Rooibos tea contains small amounts of iron, magnesium, phosphorus, sodium, chloride and potassium. These findings have practical nutritional and therapeutic implications.
Differences in ventilation patterns were observed in several instances in two consecutive ventilation studies with 127 Xe and 133Xe gas involving a group of 20 patients with COPD and other pulmonary disorders. Included were differences in the distribution of a tracer gas bolus during the initial inspiration, the distribution of gas tracer after equilibration and during gas washout, artifacts external to the lung, and variations in the half-time for gas washout. The observed discrepancies are clinically significant and could lead to erroneous or ambiguous diagnoses.
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201Tl-chloride and 204Tl-nitrate were similarly distributed in organs of mice 10 min and 60 min after intravenous injection. Autoradiographic studies were carried out with 204Tl-nitrate in rats (injected intraperitoneally) as well as in mice and dogs (injected intravenously). Thallium localized in the cells of proximal and distal convoluted tubules and collecting tubules of the kidney. In the intestines, it was distributed mostly in the cells of the smooth musculature and surface epithelium of the villi. Some silver grains were seen in the goblet cells and in the lumen as well. It localized in the sarcoplasm of the myocardium and the skeletal muscle cells. In thyroid, most of the thallium was seen in the colloidal part of the follicle. In testes, silver grains were seen in and around the cells of Sertoli and in the lumen of the seminiferous tubules. Some localized concentration in the interstitial cells of the testes was also observed.
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Xenon-133 and xenon-127 were compared by performing ventilation studies with both radionuclides in 19 patients with a variety of lung diseases. Assessment of the counting rate over the chest, relative to the radioactivity in the lungs, permitted the evaluation of each isotope in terms of usable photons detected by a scintillation camera with a large field of view and appropriate collimation. A greater photon yield was obtained with Xe-127. Markedly improved resolution was shown by measurement of a line phantom, but was not apparent on subjective appraisal of scintiphotos except in the washout phase. Xenon-127 appears to be preferable to Xe-133 because of the higher counting rates, lower patient radiation dose, and longer shelf life. In addition, a prior perfusion study using a Tc-99m radiopharmaceutical does not affect the quality of a Xe-127 ventilation study. The use of Xe-127 therefore permits the selection for ventilation studies of only those patients with suspected pulmonary embolism, and eliminates unnecessary radiation exposure. A further improvement in image quality obtained with Xe-127 should be possible with certain modifications of the scintillation camera that would permit use of the 375-keV photopeak along with the 172- and 203-keV gamma energies. Charcoal traps designed for Xe-133 will require additional shielding and longer storage time when used for Xe-127. Xenon-127, however, might be used again after appropriate processing.
The use of intravenous radio-isotope angiography in 3 cases of unilateral carotid-cavernous sinus fistula is described. The lesion gives a characteristic image pattern distinguishable from that of arteriovenous malformation in this region. An abnormal registration of intense radioactivity is seen in the early phases, accurately localised to the cavernous sinus, with a distinctive sigmoid-shaped configuration. Rapid disappearance by a paradoxical apparent increase in blood flow to the ipsilateral hemicranium. This is attributed to the massively arterialised venous drainage. This technique of demonstrating the cerebral circulation dynamically is considered a valuable diagnostic supplement to the static scintiscan and to conventional roentgen arteriography in this lesion.
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