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Objective: To assess the prognostic value of SPECT in patients with diabetes (DM) and without DM., Method: A total of 366 patients (104 women, 262 men) were examined by T1 +/- 201 or Tc-99m-MIBI SPECT of the myocardium. DM was recorded in 149 patients, 217 patients did not suffer from DM. The SPECT findings were classified as normal and abnormal perfusion (fixed or reversible perfusion defect). A serious cardiac event was defined as sudden cardiac death or non-fatal myocardial infarction. Also angina pectoris requiring revascularization was recorded., Results: During the average investigation period of 24 +/- 7 months we recorded in 147 patients with a normal load perfusion only one non-fatal myocardial infarction and the risk of a serious cardiac event was low: 0.3% per annum in the whole group. A significantly higher incidence of a severe cardiac event, 5.9% per year, was recorded in 219 patients with an abnormal finding on SPECT (10 deaths and 16 non-fatal myocardial infarctions, P < 0.01). On comparison of the frequency of serious cardiac events in groups of patients with and without DM no significant difference was found as regards normal load perfusion of the heart muscle (1.1% vs. 0%, P = NS) even in patients with an abnormal SPECT finding (5.8% vs. 6.1, P = NS)., Conclusion: SPECT myocardial perfusion makes it possible to stratify the risk in patients with DM similarly as proved previously in non-selected groups. Similarly as in patients without DM normal perfusion in diabetic patients predicts a benign prognosis.

Consistent with the worldwide development of nuclear medicine, in the Czech Republic in 1987 to 1996 partly the spectrum of used radiopharmaceutical preparations and their ratio changed. In the majority of radiopharmaceutical preparations the mean administered activity increased by 20 to 80% and the range of activities administered in different departments diminished somewhat. Adherence to principles of radiation protection of patients is assisted by guidelines of administered activities of radiopharmaceutical preparations laid down in new regulations on radiation protection valid in the CR from the middle of 1997. The radiation burden associated with the majority of examinations in nuclear medicine expressed as the effective dose is comparable with the radiation burden of radiodiagnostic examinations, only after administration of preparations with 131I, 201Tl, 67Ga and 111In it is markedly higher. Based on knowledge of the effective dose it may be concluded that the lifetime extra risk of a fatal tumour due to administration of radiopharmaceutical preparations is by two to three orders lower than the lifetime risk of spontaneous development of fatal tumours. A special feature of radiation risk is its hypothetical character--it is frequently projected into the distant future of human life, contrary to immediate non-radiation risks of some medical procedures and risks in the living environment which frequently are higher. Any examination using ionising radiation can be made only if the expected health benefit for the patient is significantly greater than the radiation risk. Excessive fear of radiation risk should not lead to refusal of justified examinations with possible subsequent serious health damage for the patient.

The authors compared retrospectively the diagnostic accuracy of three protocols--201Tl stress-redistribution, 2-day 99mTc-tetrofosmin and the dual-isotope protocol (rest 201Tl/stress99m Tc-tetrofosmin)--for the detection of ischaemic heart disease (IHD) in a total of 115 patients without previous myocardial infarction (IM). 201Tl protocol (group A) was used to examine 43 patients, incl. 15 women, mean age 51 years (38-69 years). The 2-day 99m Tc-tetrofosmin protocol was used to examine 39 patients incl. 12 women, mean age 49 years (30-71 years). The dual-isotope protocol was used in 33 patients, incl. 8 women, mean age 52 years (31-69 years). In all patients coronarography was performed, stenosis of the artery >50% was considered significant for IHD. The sensitivity of the dual-isotope protocol was 95% and 96% resp. and 92% in the 2-day tetrofosmin and 201Tl protocol, (p>0.05). The specificity of the dual-isotope protocol was 82% and 89% resp. and 88% in the 201Tl and 2-day tetrofosmin protocol, (p >0.05). The diagnostic accuracy was 91% in the dualisotope and 201Tl protocol and 92% in the 2-day protocol (p>0.05). No significant difference was revealed in the sensitivity, specificity and diagnostic accuracy for the detection of IHD between different protocols in patients without previous IM.

The sensitivity and specificity of a myocardial perfusion single-photon emission tomography (SPECT) for the detection of the coronary artery disease (CAD) was investigated. As a gold standard the coronary angiography was used--the stenosis of the artery by 50% and more was considered as significant for CAD. After performing SPECT studies patients were examined by coronary angiography according to the attending physician's judgement. In the retrospectively created group of 123 subjects (94 males and 29 females, mean age 53 years, range 30-69 years) 55 patients underwent myocardial infarction (MI). The stress was performed using a bicycle ergometer or, in case of patient's inability, an intravenous dipyridamole infusion. Before december 1995 201T1 was used in all patients, after this date only in patients with prior MI with regard to the advantage of this radionuclide for the detection of the ischemic but viable myocardium. Other patients were administered 99mTc-tetrofosmin. In our group of patients we found the high sensitivity of myocardial SPECT of 94.5% 86 (from 91), specificity of 84.4% (27 from 32) corresponding to usually values and the high diagnostic accuracy of 91.9% (113 from 123). Specificity can be impaired by marked attentuation of gamma-rays by overlying soft-tissue structures such as the breast or diaphragm. The artificial imaging of the inferior wall due to the infradiaphragmatic structures represents the most serious problem-there were four false positive findings in our group; further ones in our 99mTc-tetrofosmin studies were avoided by the routine use of the prone position recommended in the literature. The validity of SPECT myocardial perfusion findings should be verified by coronary angiography; however, one must be aware of some questionable points inherent in this comparison.

The authors assessed by means of questionnaires the activities of radiopharmaceuticals administered in departments of nuclear medicine in Czechoslovakia. The mean activities of individual radiopharmaceuticals are roughly equal as in Great Britain, but lower than in the Canadian province of Manitoba. The differences of activities used in different departments are approximately equal in all compared countries. In the Czech Republic the annual collective effective dose equivalent from nuclear medicine was 433 Sv in 1983 and 609 Sv in 1987. The mean effective dose equivalent per examination was 2.23 mSv in 1983 and 2.44 mSv in 1987. The mean effective dose equivalent per inhabitant of the Czech Republic was 0.042 mSv in 1983 and 0.059 mSv in 1987. The radiation dose of the Czech population from nuclear medicine amounts approximately to one tenth of the load from radiodiagnostics.

The authors designed and constructed device simulating the activity of the heart, based on periodic filling and emptying two rubber blowers a radioactive solution by means of two pistons in cylinders operated by two specially shaped cams. The phantom enables to control the correctness of the method and a computer programme for evaluating parameters of heart activity (ejection fraction, end-diastolic volume, pulse volume etc.) in balanced ventriculography performed by a scintillation camera coupled with a computer. The performed measurements have shown a very good agreement of the evaluated parameters with those set at the phantom. The designed device is of an original construction and was granted the author's certificate No. 238,298.