William R. Greig

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.

Absent kidney sign associated with symmetrical and uniformly increased uptake of radiopharmaceutical by the skeleton.

In 11 patients 99mTc-stannous H.E.D.P. bone scans showed absent renal images associated with symmetrical and uniformly increased uptake of radiopharmaceutical by the skeleton. These appearances are frequently seen in renal osteodystrophy but are uncommon in malignant disease. Their significance in hypervitaminosis D requires further evaluation.

The significance of the abnormal rest Thallium-201 myocardial image in coronary artery disease

Rest Thallium-201 myocardial images were abnormal in 20 out of 40 patients with arteriographically proven coronary artery disease. The myocardial image appearances did not accurately reflect the extent of coronary artery disease present. However, in 35 of the 40 patients (88%) the presence or absence of abnormalities on the rest myocardial image correleted respectively with the presence or absence of abnormal wall motion at left ventriculography. Most rest image abnormalities could be attributed to previous myocardial infarction, but in six patients myocardial ischaemia was possibly the cause. These results suggest that though myocardial fibrosis is usually the cause of rest myocardial image abnormalities in coronary artery disease, this is not invariably so. The possible therapeutic implications are discussed.

A clinical comparison of 2 h and 4 h bone scans obtained with 99mTc H.E.D.P.

A comparison of 2 h and 4 h bone scan images obtained with technetium labelled H.E.D.P. in ten patients demonstrated no increase in lesion detection rate between the 2 h and 4 h scans. The 2 h bone scans were of sufficient quality to permit identification of tumours in all cases.

Frequency and pattern of radionuclide administration to medical patients in a general hospital.

As part of a drug surveillance programme details of nuclide administration were recorded for 5288 consecutive patients admitted to the medical wards of a large general hospital.Overall use of nuclides amongst this group was found to be low, and multiple exposure during one hospital admission was rare. Exposure to radiation as a result of nuclide administration is not a major hazard when compared to the diagnostic information provided.