Search

Background: We compared SPECT and planar (99m)Tc-MIBI scintimammography (SMM) in the detection of primary breast cancer and metastatic axillary lymph node involvement, and the scintigraphic results with the histopathological/cytological findings., Material and Methods: 303 consecutive patients with 308 suspicious or indeterminate lesions observed in mammographies were entered in this study. After an intravenous injection of 740 MBq of (99m)Tc-MIBI, anterior supine, right and left lateral planar images in a prone position and a SPECT study were acquired., Results: 85 malignant and 223 benign breast lesions were confirmed by histopathology/cytology. The overall sensitivity in the detection of breast cancer was 92% (78/85) for SPECT and 82% (70/85) for planar imaging (p = NS), respectively; overall specificity was 91% (204/223) for SPECT and 91% (202/223) for planar scans (p = NS), respectively. Metastatic axillary lymph node involvement was seen in 35 patients; per-axilla overall sensitivity was 66% (23/35) for SPECT and 54% (19/35) for planar images (NS), respectively; overall specificity was 76% (38/50) and 86% (43/50), respectively (NS)., Conclusions: Our results confirm the high diagnostic accuracy of (99m)Tc-MIBI scintimammography in the diagnosis of breast cancer, and show SPECT to be slightly more sensitive than planar imaging, especially in detecting malignant breast lesions. We found the sensitivity of both imaging modalities to be quite low in the detection of metastatic axillary lymph node involvement. SPECT provides additional information to planar SMM with respect to the localization of (99m)Tc-MIBI uptake and tumour extent and improves diagnostic certainty. Our experience suggests that SPECT combined with planar SMM should be used more widely.

Radionuclide myocardial perfusion imaging (MPI) has been on the rise in Europe and the USA. Details on nuclear cardiology in the Czech Republic are not available as yet, as it is impossible to obtain comprehensive data from official registers owing to different methods of reporting and data evaluation. A questionnaire concerning nuclear cardiology activity and practice in 2001 was sent to all nuclear medicine departments in the Czech Republic. All 48 departments completed the questionnaire. In 2001, 50 planar and 54 tomographic (SPET) scintillation cameras were used. The average age of the SPET cameras was 5 years (13% of SPET cameras were >8 years old). Out of the 48 centres, 39 (81%) provided a nuclear cardiology service; the total number of cardiological studies was 15,740 in 2001 (1.5 studies/1,000 population/year). The most frequently employed method was MPI (81.7%), the frequency of which had increased by 10% compared with 2000; 26 of the 39 (67%) departments reported that MPI activity was increasing. Nevertheless, the Czech Republic nuclear cardiology activity remained below the European average (2.2/1,000 population in 1994) and, particularly, below activity in the USA (15/1,000 in 1997). The activity was rather unevenly spread. Whereas two centres with >1,000 studies/year accounted for 20% of the total MPI studies, 16 of 39 (41%) departments exhibited low activity (<200 studies/year) and accounted for only 15% of the total MPI studies. The use of SPET increased from 91% in 2000 to 94% in 2001 (only three institutes performed planar examinations). The most widely used tracer was (99m)Tc-MIBI (60% of total MPI), followed by (201)Tl (21%) and (99m)Tc-tetrofosmin (19%). ECG-gated SPET was employed by 20/39 (51%) centres, of which 11 (28%) performed it as a standard examination; 39% of the total MPI studies included this technique. Thirteen percent (5/39) of the departments used attenuation correction, and 69% (27/39) of the departments used a prone projection. Equilibrium radionuclide ventriculography, with 2,317 examinations (14.7%), ranked second among all nuclear cardiology methods, followed by first-pass angiocardiography (406 studies, 2.6%) and (18)F-FDG (163 studies, 1%).

Purpose: The authors wanted to identify those patients assessed by exercise SPECT in whom the quantification of lung Tl-201 uptake helps to evaluate disease prognosis., Methods: One hundred forty-nine patients (114 men, 35 women; 74 after myocardial infarction [MI]; mean age, 54 +/- 9 years) underwent exercise Tl-201 SPECT. The SPECT patterns were divided into normal (n = 45), fixed defects (n = 29), and inducible ischemia (n = 75). Anterior planar imaging was performed before SPECT acquisition to calculate the lung-to-heart ratio (L:H)., Results: During an average follow-up of 20 +/- 9 months, eight patients had died of cardiac causes and 13 patients experienced nonfatal MIs. Among the 45 patients with normal perfusion, no cardiac event was observed and the L:H ratio was not helpful for risk stratification. In 29 patients with fixed defects, four cardiac deaths occurred (all in patients with L:H ratios >0.5; annual event rate, 21.1% for L:H ratios >0.5 compared with 0% for L:H ratios <0.5; chi-square = 4.07, P < 0.05). Among the 75 patients with ischemia, 4 died and 13 had nonfatal MIs (annual event rate, 15.4% for L:H ratios >0.5 compared with 13% for L:H ratios <0.5; P = NS)., Conclusions: These findings suggest a benign prognosis in patients with normal SPECT (regardless of the L:H ratio). Conversely, all patients with ischemia are at high risk for future cardiac events. Quantification of the Tl-201 lung uptake seems to be valuable in evaluations of disease prognosis, especially in patients with fixed defects.

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.

Background: The purpose of this study is to compare sensitivity, specificity and accuracy of myocardial perfusion SPECT for the detection of coronary artery disease (CAD) in women and men., Material and Methods: 588 patients (455 males and 133 females, 273 after a previous myocardial infarction) underwent stress myocardial perfusion SPECT. The accuracy of myocardial perfusion SPECT was proved by coronary angiography (stenosis > 50% was considered as a CAD)., Results: The sensitivity of SPECT was slightly higher, but statistically not significant, in men than in women (94% versus 91%, p > 0.05). The specificity was higher in women than in men (93% versus 82%), but this difference was not statistically significant either (p > 0.05). The accuracy of SPECT was the same for both sexes (92%). In angiographically verified group of patients the selection bias was obvious--patients with CAD dominated (74%) and the fraction of patients with CAD in men's group (83%) was significantly higher than in women's group (50%), p < 0.05., Conclusions: No significant difference was revealed in the accuracy of myocardial perfusion SPECT in men and women. Our results are in accordance with the prevailing opinion in literature that discovered differences in sensitivity, specificity and diagnostic accuracy are usually not statistically significant or that they can be explained by the selection bias of patients in angiographically verified groups (significantly higher fraction of patients with CAD in men's group).

Purpose: The authors assessed the prognostic value of stress myocardial perfusion tomographic imaging (SPECT) in patients with recurrent angina or inconclusive results of exercise electrocardiographic tests after successful percutaneous transluminal coronary angioplasty (PTCA)., Materials and Methods: After PTCA, 70 patients (54 men, 16 women; 41 after myocardial infarction; mean age, 56 +/- 9 years) underwent TI-201 or Tc-99m sestamibi SPECT studies. SPECT patterns were divided into normal (n = 25), fixed defects (n = 15), and reversible or combined fixed plus reversible defects (n = 30). A cardiac event was defined as either cardiac death, nonfatal myocardial infarction, or unstable angina requiring further revascularization., Results: During an average follow-up of 25 +/- 10 months, two patients had severe outcomes (one cardiac death and one nonfatal myocardial infarction), and revascularization was required in 13 patients. In patients with normal SPECT or fixed defects, the annual event rate was low (1.2%), with only one revascularization. In patients with reversible or combined defects, the annual event rate was significantly greater (22.4%; chi square = 17.32, P = 0.00003)., Conclusions: Normal perfusion or fixed defects predict a benign prognosis in patients after successful PTCA. The presence of stress-induced reversible defects appears to be the best predictor of future cardiac events.

Background: The information on the results of the survey of collective effective dose SE to children in the Czech Republic (CR) due to nuclear medicine examinations performed during the one-year period July 1995-June 1996., Methods: The estimate of SE was based on the annual frequency of nuclear medicine procedures and the type and amount of administered radiopharmaceuticals provided by the General Health Insurance Company covering 75% of the CR population., Results: In the period considered, 15,281 examinations of children younger than 18 years were performed, which represented 7.5% of total nuclear medicine examinations in the CR. The annual SE 43.8 man Sv formed 5.1% of the collective effective dose to all patients examined by nuclear medicine procedures in the CR. The contributions of procedures in various body systems of children to the annual SE: urinary tract 32.8%, bone 30.4%, brain 12.8 %, cardiovascular 6.4%, GIT 6.0%, thyroid 4.4%, lungs 3.0%, other 4.2%. In comparison with a similar survey performed in the CR in 1987 (based on a questionnaire) there was an increase in SE to children younger than 15 years by a factor of 2.8, mainly due to the expansion of kidney and bone investigations., Conclusions: The mean effective dose per exam to children younger than 15 years was 60% of that for adults, which was in agreement with the requirement that the radiation burden of children should not exceed that of adults. The use of data from the Insurance Company for regular conducting of such surveys appeared to be not as cumbersome and time-consuming as questionnaire surveys.

Purpose: This study used radionuclide angiography to evaluate semiquantitatively the hepatic arterial blood flow changes associated with cirrhosis., Methods: The parameters of net arterial hepatic perfusion were estimated by analysis of first-pass flow studies in 11 control participants and in 15 patients with cirrhosis (Child-Pugh classification B-C). Hepatic, renal, and splenic time-activity curves were generated, normalized per pixel, and corrected for background. The rate of hepatic arterial blood flow was compared with the reference kidney and spleen perfusion using the hepatorenal and hepatolienal perfusion indices, respectively. These indices were defined as: PI = area under hepatic curve limited by time of the renal (splenic) curve peak/area under renal (splenic) curve to its peak, Results: The values of both these perfusion indices are significantly greater in the patients with cirrhosis than in controls (hepatorenal perfusion index, P < 0.01; hepatolienal perfusion index, P < 0.05). The values of the hepatic perfusion index (the ratio of the arterial to the total liver blood flow), which were also calculated, were elevated in the patients with cirrhosis (P < 0.01)., Conclusions: The results confirm that the net hepatic arterial blood flow is increased in patients with cirrhosis. Radionuclide angiography accompanied by calculation of arterial perfusion indices may provide semiquantitative parameters of net hepatic arterial blood flow.

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.

Our modification of a method for the absolute quantification of gallium-67 uptake in lungs with a scintillation camera and computer is described. The uptake of 67Ga in lungs, expressed in percentage of administered radioactivity, was determined by the transmission-emission method. We proved theoretically and experimentally that a 67Ga planar source could be replaced with a 57Co planar source. The performance of lung perfusion scans allows a more accurate delineation of the regions of interest on gallium scans. The method was applied to control subjects (n = 27) and to patients (n = 114) suffering from biopsy-proven pulmonary sarcoidosis (28 with inactive and 86 with active disease). The obtained results were compared with chest X-ray findings, the percentage of lymphocytes in the bronchoalveolar fluid (BAF-ly%), and serum angiotensin-converting enzyme (SACE) values. The method seems suitable for the assessment of disease activity in sarcoidosis. It is more accurate in detecting parenchymal involvement in lung sarcoidosis than the commonly used X-ray criteria. No correlation was found between 67Ga uptake and the BAF-ly% and SACE values.

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.

A total of 39 99mTc eluates obtained from 9 99Mo--99mTc generators delivered by The Radiochemical Centre Amersham during one year was studied with regard to their radionuclide purity. Using a Ge(Li) spectrometer the contaminants 60Co, 103Ru, 131I, 134Cs, 140Ba, 140La and 188Re were found in 99mTc-eluates with average levels ranging from 2.9 X 10(-3) to 2.8 X 10(-1) per cent of 99mTc activity. The additional total body absorbed dose caused by these contaminants, as calculated from their average content in 99mTc eluates, was less than 1% of the dose due to 99mTc pertechnetate.

Several methods for the measurement of dead time and for evaluation of the dependencies required to correct dynamic studies for dead-time losses are described. Two program variants were written to produce time-activity curves in the selected areas of interest of the dynamic studies with computer's correction of dead-time losses; these variants are part of the system of programs for complex processing of scintigraphic studies set up for a Clincom instrument. The first variant performs correction on the basis of the registered count rate in the whole image, while the second variant makes us of the additional reference source positioned on the periphery of the camera visual field.

A set of computer programs written for Clincom allow the evaluation of the depth effect in Muehllehner's tomographic camera using MTFs and specificity as well as new quantites. The depth effect of the camera is compared with that of a rectilinear scanner.

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.

Using the specific absorbed fractions reported by Smith and Warner, the radiation doses absorbed by the embryo in early pregnancy were calculated for various radiopharmaceuticals used in the diagnostic procedures of nuclear medicine. Radiopharmaceuticals are considered which are excreted predominantly through urine and cause the doses to the embryo to be 40%--90% higher than gonad doses. Also discussed are large differences of doses reported by various authors to the embryo by 99mTc-pertechnetate.

The device manufactured is equipped with the NaI(Tl) scintillation crystal situated in a thick lead shielding. The cavity in the lead shielding allows inserting a hand which is in contact with the detector during the measurements. The apparatus exhibits low values of the minimum detectable superficial activity of radionuclides emitting low energy gamma-rays (e.g. 125I, 99mTc). The apparatus complies with the requirements for a sensitive and prompt monitoring the contamination of hands in departments of nuclear medicine with the numerous staff.