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Biomedical subjects

H Meindok

Publications and source records attributed to H Meindok.

15 recordsLinked to original sources
PubMed1992

Advantages of peripheral radiogrametry over dual-photon absorptiometry of the spine in the assessment of prevalence of osteoporotic vertebral fractures in women.

Since osteoporosis develops in most postmenopausal women and is probably the most important single factor in the pathogenesis of osteoporotic fractures of the spine, hip, and wrist (and at other sites), methods suitable for mass screening should be developed. In this study of 97 women aged 24-79, measurements of the lumbar spine mineral content by dual-photon absorptiometry (DPA) were compared with the summed combined cortical thickness measurements from radiographs of the radius and metacarpal II (MR). There was good correlation between the two methods (r = 0.90). The correlation of age with MR was higher than with DPA. The correlation of years postmenopause was significant with MR but not with DPA. Taking the -2 SD level of the premenopausal means to be previously established vertebral fracture thresholds, 24% of the DPA measurements, but no MR measurements in patients with vertebral compressions, were above the fracture threshold. Since MR measurement requires taking only two small plain radiographs using ordinary x-ray equipment, it is concluded that this less expensive method is better suited to screening for osteoporotic vertebral fracture risk in postmenopausal women than DPA.

Absorptiometry, Photon↗
PubMed1992

Diagnosis of bleeding mycotic iliac aneurysm on technetium-99m renal scan.

Since abdominal aneurysms are common in the elderly, it is not unusual to see incidental aneurysms on renal scintigraphy performed for other reasons. However, the initial discovery of a bleeding aneurysm on a renal scan in a patient with salmonella septicemia who has no other obvious focus of infection should be considered suspicious for mycotic aneurysm. A prompt diagnosis is crucial to avoid catastrophic outcome associated with delayed surgical intervention.

Aged↗
PubMed1986

Radionuclide assessment of regional left ventricular function in acute myocardial infarction.

To determine changes in global and regional left ventricular function following acute myocardial function, 17 patients underwent radionuclide angiography at 3 and 10 days post infarction. Five patients had nontransmural myocardial infarction and 12 had transmural infarction (six anterior and six inferior). There were no previous infarctions in 16 (94%) patients. Regional ejection fractions were calculated by dividing the left ventricle into four quadrants using the geometric center of the left ventricle on the end-diastolic frame as a reference point. At 3 days post infarction, 8 of 17 (47%) patients had an abnormality of global left ventricular ejection fraction (LVEF), whereas 16 of 17 (94%) patients had abnormalities of one or more regional ejection fractions (p less than 0.01). Between 3 and 10 days, global LVEF did not change (51% to 49%, p = NS). However, there were significant changes in 23 of 68 (34%) regional LVEFs. These changes did not relate to type, ECG location, creatine kinase (CK) size of infarction, or initial global LVEF. These data suggest that regional LVEF is a sensitive technique for identifying segmental dysfunction associated with myocardial infarction. In addition, significant changes occur in regional LV function during acute myocardial infarction despite stable serial global LV performance.

Adult↗
PubMed1985

Quantitative radionuclide scanning in metabolic bone disease.

A simple method of quantifying skeletal uptake of 99Tcm-methylene diphosphonate, using a rectilinear scanner and a simultaneously image standard, is described. The pattern of quantified uptake in ten regions of the skeleton, the sacro-iliac joints and kidneys in 57 controls and 54 patients with various metabolic bone disease is presented. This method distinguishes patients with primary hyperparathyroidism and osteomalacia from controls with a sensitivity adequate for clinical purposes. In primary hyperparathyroidism the increased skull uptake of tracer correlated well with levels of serum alkaline phosphatase, plasma parathyroid hormone, urinary hydroxyproline excretion and the degree of intracortical resorption in the metacarpal bones. The skull uptake in oestoporosis was normal or moderately elevated and correlated well with bone mass density measurements of the radius. Patients with osteomalacia also showed the greatest increase in tracer uptake in the skull. Patients with thyrotoxicosis differed from most other patients by showing moderately increased uptake in shafts of long bones. We propose our method of quantitative bone uptake as a useful noninvasive test to detect metabolic bone disease and to monitor responses to therapy of bone disease.

Adolescent↗
PubMed1979

Lung function in diaphragm pacing.

Electric stimulation of the diaphragm via the phrenic nerve to induce ventilation has recently been used for the long-term management of chronic ventilatory insufficiency. Since 1973 three patients with inadequate alveolar ventilation have been treated with diaphragm pacing at the Toronto Western Hospital. Two, who had quadriplegia due to lesions of the spinal cord in the upper cervical region and a severe restrictive ventilatory defect, were treated with continuous diaphragm pacing. The third patient required assisted nocturnal ventilation because of primary alveolar hypoventilation. All three patients tolerated the diaphragm pacing well, and pulmonary function tests showed satisfactory gas exchange with the patients breathing room air. This form of therapy seems to be a practical clinical method of managing chronic ventilatory failure in patients with lesions of the upper cervical cord or primary alveolar hypoventilation.

Adolescent↗
PubMed1978

Detection and pathogenesis of visceral calcification in dialysis patients and patients with malignant disease.

Scintiscanning to detect the uptake of bone-seeking radioactive isotopes by soft tissue is a promising technique for the in vivo study of visceral calcification. Visceral uptake of such radioisotopes was studied in 40 patients: 22 undergoing long-term dialysis, 9 with malignant disease and hypercalcemia and 9 with primary hyperparathyroidism and hypercalcemia.Fifteen patients, 11 undergoing dialysis and 4 with malignant disease, had radioisotope uptake in the lungs, and 5, 3 undergoing dialysis and 2 with malignant disease, had uptake in the stomach. None of the patients with primary hyperparathyroidism had visceral uptake, nor did the patients with uptake have radiologic evidence of pulmonary or gastric calcification. The dialysis patients with visceral uptake had a mean calcium x phosphate product of 84.3 +/- 23.7 (standard deviation), which was significantly greater (P < 0.001) than that of patients without such uptake (59.2 +/- 14.0). Similarly, in patients with malignant disease and visceral uptake the Ca x P product was 72.2 +/- 6.4 - significantly greater (P < 0.005) than that of patients without such uptake (49.3 +/- 6.7).These findings indicate that scintiscanning for the visceral uptake of a bone-seeking radioisotope is a simple and effective technique for the in vivo study of visceral calcification. An elevation in the Ca x P product seems to be the single most important factor in the production of visceral calcification.

Adult↗
PubMed1978

Visceral calcification and the CaXP product.

The authors studied the presence of visceral calcification as evidenced by the visceral uptake of bone-seeking radionuclides during the course of a bone scan among 22 patients with terminal renal failure maintained on dialysis, nine patients with hypercalcemia secondary to malignancy, and nine patients with primary hyperparathyroidism. Uptake by the lungs or stomach was observed in 11 renal failure patients (50%) and in four of those with malignancy and hypercalcemia (44%). None of the patients with primary hyperparathyroidism had evidence of visceral calcification. The serum CaXP product was significantly higher among those with visceral calcification than those without. The results of this study indicate that a CaXP product of 60 represents the saturation product of calcium phosphate in serum above which spontaneous precipitation of this salt may occur in such viscera as stomach and lungs.

Adult↗
PubMed1976

Liver scan in Budd-Chiari syndrome.

Seventeen liver scans were performed in seven patients with occulsion of hepatic veins: the Budd-Chiari syndrome. When some, but not all liver veins were occluded, markedly diminished uptake over the affected segments was usually seen (absence of uptake may occur in acute infarction and in chronic cases). When all major liver veins are occluded, markedly diminished uptake is seen over the peripheral parts of the right and left lobes with a triangular midline area of normal or excessive activity. The latter effect is probably caused by uptake in segments surrounding the inferior vena cava (frequently the caudate lobe) that have direct venous drainage. This liver-scan appearance is characteristic enough to warrant consideration of the Budd-Chiari syndrome as the first diagnosis. Good correlation existed between selective venography and liver-scan findings. The usefulness of liver scans in the followup after portocaval shunting is illustrated in one patient.

Adult↗
PubMed1972

Visualization of arterial and arterial graft patency by intravenous radionuclide angiography.

A method of visualizing patency of arteries and arterial grafts by means of intravenous (99m)Tc pertechnetate using a Nuclear Chicago Pho/Gamma HP camera is described. Polaroid pictures showing normal arteries in the upper and lower limbs, as well as partial and complete occlusion of arteries and the state of arterial bypass grafts in pre- and postoperative patients are compared with conventional arteriograms. The advantages and limitations of this method are discussed.

Adult↗