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Biomedical subjects

R G Bessent

Publications and source records attributed to R G Bessent.

At least 73 records · Page 4Linked to original sources
PubMed1979

Can the extent of coronary artery disease be predicted from thallium-201 myocardial images?

The accuracy with which the extent of coronary artery disease can be predicted from stress thallium-201 myocardial images has been assessed in 81 patients with chest pain. Whereas the appearance of the myocardial images was both a sensitive means of detecting coronary artery disease (images abnormal in 43 of 47 patients with abnormal coronary arteriograms) and specific in excluding it (images normal in 31 of 34 patients with normal arteriograms), there was poor correlation between the extent of disease predicted from the Tl-201 images and the findings at arteriography. It is concluded that although stress Tl-201 myocardial imaging is a useful method for the noninvasive diagnosis of coronary artery disease, it cannot be relied upon to predict the number of abnormal vessels.

Adult↗
PubMed1978

A quantitative approach to the analysis of the normal thallium-201 myocardial image.

The visual interpretation of Thallium-201 myocardial images is made more difficult by nonhomogeneity of myocardial tracer uptake in normal studies. To increase the objectivity of the study, the variation in count density in different myocardial areas has been calculated using a computer regions of interest technique in 14 healthy, young subjects following intravenous injection of the radionuclide at rest and in 10 after injection during maximal exercise. The "normal ranges" for regional Thallium-201 uptake so obtained are presented and discussed.

Adult↗
PubMed1978

The estimation of whole-body zinc and Zn turnover in rheumatoid and osteoarthritis using 65Zn tracer.

1. A method of estimating whole-body zinc, and Zn balances using a two-compartment model in combination with whole-body counting of 65Zn, is described. The method is applied to patients with rheumatoid and osteoarthritis. 2. The results suggested that there was not a wide variation in whole-body Zn and Zn turnover in individuals with these two diseases and no clearcut difference between patients with one or the other.

Adult↗
PubMed1978

Clinical value of delayed thallium-201 myocardial imaging in suspected acute myocardial infarction.

Fifty patients with acute chest pain had thallium-201 myocardial imaging performed three to six days after emergency admission to hospital. The image was abnormal in 20 out of 22 patients with acute transmural myocardial infarcts but in only 1 of 5 with acute subendocardial infarcts. Indistinguishable scan abnormalities caused by old infarcts were seen in 7 patients, and caused by myocardial ischaemia in 1 patient. A single thallium-201 myocardial scan some days after the onset of symptoms appears to be of little value in the clinical assessment of patients with suspected acute myocardial infarction.

Acute Disease↗
PubMed1978

The use of whole-body retention of Tc-99m diphosphonate in the diagnosis of metabolic bone disease.

The limited role of bone scanning in the diagnosis of metabolic bone disease might be considerably improved by accurate quantification of skeletal uptake of the radiopharmaceutical. Using a standard shadow-shield whole-body monitor, we have measured whole-body retention (WBR) of Tc-99m HEDP up to 24 hr in 11 patients with renal osteodystrophy (mean WBR 88.6% at 24 hr); in ten patients with Paget's disease (mean 56.9%); in seven patients with osteomalacia (mean 40.7%); in five patients with primary hyperparathyroidism (mean 50.7%); in four patients with osteoporosis (mean 21.2%); and in 12 normals (mean 19.2%). The osteoporotic group could not be differentiated from the normal group, but the other groups were significantly different from the normal group at 24 hr (p less than 0.002), and each individual rest for the 24-hr WBR of Tc-99m HEDP in these groups lay outside our normal range. This test may, therefore, provide a sensitive means of detecting conditions with increased bone turnover. We obtained measurements of plasma activity of Tc-99m HEDP in these patients up to 24 hr, and 4-hr bone to soft-tissue ratios from bonescan images, but little additional information resulted.

Adolescent↗
PubMed1978

The role of bone scanning in osteomalacia.

The presence of eight "metabolic features" was assessed on the bone scintigrams of ten patients with osteomalacia. In all of these bone images, sufficient features were present to strongly suggest a metabolic disorder. There scintiphotos were included in a controlled blind study using 30 normal bone scans and 20 scans of metastatic disease. Nine of the ten metabolic bone images were correctly identified by two independent observers. Skeletal uptake of radiotracer, expressed as bone-to-soft tissue ratio, was significantly higher in the osteomalacic patients than in a group of 80 controls.

Adolescent↗
PubMed1977

A comparison of the sensitivity and accuracy of the 99TCm-phosphate bone scan and skeletal radiograph in the diagnosis of bone metastases.

The accuracy and sensitivity of the 99Tcm-phosphate bone scan and conventional skeletal radiology have been compared in 372 patients with documented malignant disease and 75 control subjects. Results indicate that the bone scan is a more sensitive method for the detection of skeletal metastases. The incidence of false-positive results with the bone scan is acceptably low. A protocol for the investigation of patients with suspected malignant disease of bone is suggested.

Adolescent↗
PubMed1977

The forms of vitamin B12 on the transcobalamins.

1. The transcobalamins from normal serum were obtained in two fractions. One contained transcobalamin I and transcobalamin III: the other contained transcobalamin II. The forms of vitamin B12 in the two fractions were then examined. 2. Methylcobalamin and adenosylcobalamin were found in both fractions. Hydroxocobalamin was found in the fraction containing transcobalamin I and transcobalamin III. Cyanocobalamin was found in both fractions in two cases, in the transcobalamin III fraction only in one case and was absent in one case.

Blood Proteins↗
PubMed1976

Radioactive technetium phosphate bone scanning in preoperative assessment and follow-up study of patients with primary cancer of the breast.

Seventy-five female patients with early primary cancer of the breast were studied by bone scanning with 99mTc labeled phosphate at the time of initial presentation and serially during follow-up examination. Eleven patients had an abnormal bone scan at the time of presentation. During follow-up periods, which have ranged from three to 34 months with a mean of 16 months, abnormal bone scans have developed in a further 13 patients. To date, nine of the 24 patients with an abnormal bone scan have died, while only one of the 51 with a persistently normal scan has died. It is concluded that an abnormal bone scan carries a significant risk of earlier death due to metastatic disease.

Adult↗
PubMed1975

Mechanical deficiencies in scintillation counters, scanners, and gamma cameras.

After an accident involving a scintillation counter, the machanical integrity of scintillation counters and their stands, rectilinear scanners, and gamma cameras was examined. An alarming proportion of these divices were found to be poorly designed with consequent danger to patients and staff. This class of equipment should be covered by standards incorporated in a comprehensive hospital technical memorandum.

Accident Prevention↗
PubMed1975

The application of the 99Tcm phosphate bone scan to the study of breast cancer.

Comparison of the gamma camera bone scan and radiological survey in 190 patients with breast cancer has confirmed the superiority of the bone scan in the positive diagnosis of skeletal metastases. In 47 patients with known (X-ray positive) bony metastases the scan was positive in all but 2, and in 24 (50 per cent) the scan showed more lesions than the X-ray had indicated. In 60 patients with a clinical suspicion of bone metastases but negative X-rays, the scan was positive in 29 (48 per cent). Eighty-three patients with primary breast cancer were studied at the time of initial presentation. All had a normal radiographic skeletal survey but 24 (27 per cent) had scan evidence of occult metastases. It is concluded that a bone scan is indicated in all patients with breast cancer where skeletal metastases are suspected. Repeated bone scans may introduce new therapeutic possibilities, by providing an earlier objective index of progression of metastatic disease and also by providing a quantitative method of assessing the response to therapy.

Adult↗
PubMed1975

Dynamic studies with 99mTc-HEDP in normal subjects and in patients with bone tumors.

Blood clearance, urinary excretion, and spinal uptake of 99mTc-HEDP have been measured in ten normal control subjects. Blood clearance from 15 min is biexponential. Approximately 70% of the administered activity was excreted in the urine within 6 hr of injection. Spine-to-background ratios rise sequentially with time. Net normal bone uptake rises little after 2 hr and improved visualization of the normal skeleton therafter is due to reduction of blood background activity. In 13 patients with bone tumors, direct measurement of diphosphonate uptake by the tumor-involved and corresponding normal bone showed a continued rise in diphosphonate levels in the tumor-involved bone due to increased metabolic activity.

Adult↗