Biomedical subjects
Publications and source records attributed to M V Merrick.
Axillary lymphoscintigraphy was performed by the technique of Agwunobi and Boak (1) in 68 patients with operable cancer of the breast and 11 patients with benign disease. Contrary to their previous report, scans were found to be indistinguishable from normal in the majority of breast cancer patients with interpretable scans, and no pattern of uptake was found which was typical of carcinoma in the corresponding breast.
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Four selenium-labeled free bile acids and four selenium-labeled conjugated bile acids, labeled with Se-75 at the C-19, C-22, C-23, or C-24 position, have been synthesized and their absorption and excretion compared with that of [24-14C]cholic acid, following both oral and intravenous administration. All but one of the compounds is absorbed and excreted in bile to a significant extent. One compound, SeHCAT, has been selected for particular study. It is quantitatively absorbed from the gut at the same rate as cholic acid, and both are excreted into the bile at the same rate. It remains almost entirely confined to the enterohepatic circulation (the gut, liver, and biliary tree) and excretion is exclusively fecal. Whole-body retention, measured for 41 days, and tissue distributions suggest that the absorbed radiation dose would be small compared with that in many established tests. Such a compound offers the possibility of a simple, novel, and aesthetically acceptable method of investigating small-bowel disease. It therefore merits further investigation.
A new technique of axillary lymphoscintigraphy has been investigated in thirty patients with breast carcinoma. Intradermal injection of 100 muCi technetium-99m antimony sulphide colloid in 0.1 ml buffer produced satisfactory scans of axillary lymph-nodes in twenty-seven patients (90%). Ten patients with node metastases from breast cancer (9 confirmed histologically) had a defect in the lower axillary uptake on the side of the lesion. Three of the remaining seventeen patients with breast cancer and normal scans had nodal metastases seen histologically, but in two these were micro-metastases only. Axillary lymphoscintigraphy improved considerably the clinical assessment of node status, and corrected the clinical classification in five of six patients who had been misclassified by clinical examination.
Radioisotope scintigraphy of the kidney and intravenous urography have been compared in 79 children with bacteriologically proven urinary tract infections, followed up over a period of between one and four years. Both techniques were in agreement as to the presence or absence of an abnormality, and the extent of any abnormality present, in 93.5% of the kidneys studied. There was a discrepancy in ten kidneys. Excretion urography has a sensitivity of 0.86 and a specificity of 0.92 in the detection of pyelonephritic scarring in children. Radioisotope scintigraphy has a sensitivity of 0.96 and a specificity of 0.98. It is therefore concluded that radioisotope scintigraphy is the preferred technique.
Scintigraphy using technetium-labelled methylene diphosphonate was performed on 110 scoliotic patients six months after an attempted fusion and the findings compared with those at exploration to detect the possible sites of pseudarthroses. The majority of patients (65 per cent) had a uniform uptake of isotope over the fused area and all but one had a solid fusion. A second group (35 per cent) had a more patchy uptake and eight of the nine patients with pseudarthroses were in this group. Pseudarthroses were detected as localised areas of increased uptake but there were also a number of false positives and scans that were difficult to interpret due to continuing new bone formation in immature fusions. In those scans performed after one year the pseudarthroses which had been missed were seen more clearly in contrast to the diminished generalised activity in the fused area.
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Techniques of prostatic lymphoscintigraphy using 99mTc phytate (TP) and 99mTc antimony sulphide colloid (ASC) have been evaluated in 30 patients. The most successful technique was a superficial perianal injection of ASC. In general, definition of the regional lymph nodes lacked the precision and clarity that would be required for the technique to be used in staging of prostatic or other pelvic tumours; further development of the technique is recommended.
Indirect voiding radionuclide cystourethrography has been compared with micturating cystourethrography in 57 children with urinary tract infections. A quasi-quantitative technique utilizing a mini-computer to optimize the images from the gamma camera has been shown to be at least as sensitive as conventional radiological techniques but to give these results without catheterization, at a lower radiation dose and at lower cost.
A new preparation of 111In DTPA for intrathecal administration has been tested and found to be a safe and highly efficacious cisternographic agent. The rate of removal of 111In DTPA from the C.S.F. and from the whole body has been measured and has been found to be of no diagnostic value in the distinction between patients with cerebral atrophy and those with normotensive hydrocephalus. Long-term retention studies show no evidence of significant long-term retention of indium in the C.S.F. The absorbed radiation dose has been investigated and found to be in good agreement with previous estimates based upon extrapolated data.
Seventy-four patients with carcinoma of the prostate were studied annually by combined radiological and 18F scintigraphy over a 5-year period. Of the patients who have no radiological evidence of bone metastases, 25% have a positive 18F bone scan. Follow-up of these patients has shown that scan abnormalities perceded x-ray changes from between 1 to 4 years. False negative scans were not seen with 18F which allows for greater accuracy in the detection of skeletal metastases. Teh accurate staging of carcinoma of the prostate cannot be made without bone scanning. Preliminary results with 111In bleomycin as an adjunct to 18F have shown this to be a useful radio-pharmaceutical to distinguish metastases from benign lesions, and further studies are warranted.
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