Abnormal uptake of technetium-99m hexakis-2-methoxyisobutylisonitrile in a primary cardiac lymphoma

Abnormally high uptake of technetium-99m hexakis-2-methoxyisobutylisonitrile (^99mTc-SESTAMIBI) in the right ventricle and in the septum was observed in a 47-year-old woman initially presenting with dysarthria and left hemiparesis. Endomyocardial biopsy demonstrated a high-grade malignant non-Hodgkin's lymphoma. Complete remission was achieved by combined cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) chemotherapy and radiotherapy of the heart and mediastinum. The post-remission single photon emission tomography (SPET) ^99mTc-SESTAMIBI study showed a homogeneous distribution pattern, in agreement with echocardiography computed tomography and magnetic resonance imaging. Increased uptake of ^99mTc-SESTAMIBI, a myocardial perfusion agent, has been observed in some benign and malignant tumours. It may prove to be useful in the diagnosis and follow-up of malignancies. Offprint requests to: G. Medolago     

Reproducibility of quantitative hexakis-2-methoxyisobutylisonitrile single photon emission tomography in stable coronary artery disease.

The quantification of myocardial perfusion abnormalities is necessary to allow comparison of repeated studies, especially in the evaluation of the success of medical, interventional or combined treatment in stable coronary artery disease or in evolving myocardial infarction. The purpose of this study was to assess inter-observer reproducibility of tomographic study processing using a semi-automatic quantitative programme. Technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-Sestamibi) was chosen for tomographic imaging of repeated rest-stress studies in patients with stable coronary artery disease. The quantification was performed using a modification of the Cedars polar coding and comparison with the normal data base. The perfusion defects were quantified separately for each standard perfusion area [left anterior descending (LAD), right coronary (RCA) and left circumflex (LCX) arteries] and total area of hypoperfused myocardium. The inter-observer variability for 40 tomographic studies was accomplished. The defects were the largest in the LAD perfusion area (average 19.7% of the normalized LAD supply area) with an inter-observer correlation of 0.84 for this region. The greatest variability was found for the LCX region (r = 0.55) and is attributed to a small average perfusion defect (7.1%), only 18 studies having abnormal perfusion in this area. In total, an average 14.3% of the left ventricular myocardium was significantly hypoperfused, and the inter-observer correlation was 0.87. These results show good inter-observer reproducibility using semi-automatic quantitation of perfusion defects. Careful interpretation of smaller defects in the evaluation of treatment results is advised when repeated 99mTc-Sestamibi single photon emission tomography studies are processed by more than one observer.     

Anatomically derived attenuation coefficients for use in quantitative single photon emission tomography studies of the thorax

Elimination of errors due to poor attenuation correction is an essential part of any quantitative single photon emission tomography (SPET) technique. Attenuation coefficients (_Tc) for use in attenuation correction of SPET data were determined using technetium 99m and cobalt 57 flood sources and using topographical information obtained from computed tomography (CT) scans and magnetic resonance (MR) images. In patients with carcinoma of the bronchus, the mean attenuation coefficient for ^99mTc was 0.096 cm^–1 when determined across a transverse section of the thorax at the level of the tumour by means of a ⁵⁷CO flood source (13 patients) and 0.093 and 0.074 cm^–1 as determined from CT scans for points in the centre of the tumour and contralateral normal lung, respectively (21 patients). In 18 patients with breast tumours, the mean attenuation coefficient for ^99mTc was 0.110 and 0.076 cm^–1 when determined from MRI cross-sections for points in the centre of the tumour and normal contralateral lung, respectively. This indicates significant overcorrection for attenuation when the conventional value of 0.12 cm^–1 is used. A value in the range 0.08–0.09 cm^–1 would be more appropriate for SPET studies of the thorax. An alternative approach to quantitative region of interest (ROI) analysis is to perform attenuation correction appropriate to the centre of each ROI (using topographical information derived from CT or MRI) on non-attenuation-corrected reconstructions.     

Unexpected uptake of technetium 99m hexakis-2-methoxy-isobutylisonitrile in giant lymph node hyperplasia of the mediastinum (Castleman's disease)

The case of a patient with giant lymph node hyperplasia of the mediastinum who unexpectedly showed focal uptake of technetium 99m hexakis-2-methoxyisobutylisonitrile (^99mTc-MIBI) is presented in this article. The patient was included in our research programme of tumour imaging with ^99mTc-MIBI because the appearance of the mass on the chest radiogram and CT scan resembled a mediastinal tumour. Final diagnosis of giant lymph node hyperplasia was achieved through histopathological examination of the surgically removed lymph node.Offprint requests to: C. Aktolun     

Dobutamine 99mTc-MIBI single-photon emission tomography: non-exercise-dependent detection of haemodynamically significant coronary artery stenoses

Dobutamine pharmacological stress testing in conjunction with technetium-99m methoxyisobutylisonitrile single-photon emission tomography (MIBI SPET) may be a useful alternative to convential exercise stress MIBI SPET for the detection and localisation of coronary artery stenoses. Therefore, 35 patients with stenoses ( 50% diameter reduction) of one or more coronary arteries were selected for dobutamine MIBI SPET. Each patient underwent MIBI injection at rest and during dobutamine infusion with incremental doses (5, 10, 15 and 20 g kg^–1 min^–1). A conventional exercise stress test (EST) was performed in all patients. Peak double product during steady-state dobutamine infusion (18 200 ± 4200 mmHg min^–1) was lower (P = 0.0001) than during EST (21 700 ± 4900 mmHg min^–1). Image quality was good in all but one patient, who had to be excluded from data analysis due to excessive hepatobiliary MIBI activity. Dobutamine-induced perfusion abnormalities were observed in 30/34 MIBI SPET studies, resulting in an overall detection rate for coronary artery disease of 88%. A pathological EST was observed in 23/34 patients (68%). The detection rate of individual coronary artery stenoses was 85% (28/33) for stenosess with a severe diameter reduction (>70%) and 50% (12/24) for stenoses with a moderate diameter reduction ( 50–70%). In particular, sensitivity and specificity for the detection of moderate and severe stenoses ( 50%) were 75%/100% for left anterior descending, 67%/95% for left circumflex and 67%/69% for right coronary artery stenoses. Dobutamine MIBI SPET is a well-tolerated, non-exercise-dependent test for detection and localisation of haemodynamically significant coronary artery stenoses. The use of dobutamine allows a stepwise increase in pharmacological stress similar to EST and is especially useful in patients who are unable to exercise. Correspondence to: E. Voth     

SPECT在冠心病危险度分层方面的应用

应用门控心肌灌注SPECT测得的心肌灌注缺损和负荷后左室射血分数(left ventricular ejection fraction,LVEF)相结合进行危险度分层,对非致死性心肌梗死和心脏性死亡的风险进行评估以指导临床选择最佳治疗方案。对于射血分数(ejection fraction, EF) ≥ 30%,总差值分(即总负荷评分与总静息评分的差值,summed difference score, SDS)>7的中高危患者,宜进行血流重建术(revascularization);SDS为2~7的患者,若EF>50%则为低危,可给予药物治疗,而EF为30%~50%者则予药物治疗及血流重建术;若为未见心肌缺血的极低危患者,则宜药物治疗。     

Direct comparison of technetium 99m-sestamibi and technetium 99m-tetrofosmin cardiac single photon emission computed tomography in patients with coronary artery disease

Background  Technetium 99m-labeled sestamibi and tetrofosmin tomography have shown high diagnostic accuracy in the detection of coronary artery disease (CAD). However, few data are available comparing sestamibi and tetrofosmin imaging in the same patients. The aim of the study was to determine the image quality of the two tracers and to compare the results of exercise sestamibi and tetrofosmin tomography in the same patients. Methods  The results of exercise-rest sestamibi and tetrofosmin myocardial tomography were compared in 32 patients with suspected or known CAD who underwent coronary angiography. Image quality was evaluated subjectively. Regional tracer distribution was visually assessed and quantitatively measured in 22 segments/patient. Results  At coronary angiography 7 patients had normal coronary vessels, 11 single-vessel, and 14 multivessel CAD (≥50% luminal stenosis). Image quality judged visually was comparable with the two tracers. Heart/lung and heart/liver ratios for sestamibi and tetrofosmin were not different. At visual analysis, 68% of the patients with CAD had abnormal findings with sestamibi and 76% with tetrofosmin (p=NS). At quantitative analysis, 92% of the patients with CAD had abnormal findings with sestamibi and 96% with tetrofosmin (p=NS). At both visual and quantitative analyses, sensitivity, specificity, and diagnostic accuracy in the detection of individual stenosed vessels were not different between the two tracers. Moreover, for both tracers sensitivity, specificity, and diagnostic accuracy in the detection of diseased vessels were significantly higher (all p<0.05) at quantitative compared with visual analysis. Finally, defect size and severity were similar for the two tracers. Conclusions  Exercise-rest sestamibi and tetrofosmin tomography yielded images of comparable quality and provided similar results in the identification of patients with CAD and in the detection of the individual stenosed coronary vessels.     

Amplitude analysis of stress technetium-99m methoxy isobutylisonitrile images in coronary artery disease

To determine the role of rest and stress gated technetium-99m methoxyisobutylisonitrile (sestamibi), in the detection of coronary artery disease, routine Fourier analysis of these images was performed with the best septal left anterior oblique (LAO) position of 20 patients (17 men, 3 women; aged 40–75 years) who also underwent rest or redistribution/stress single photon emission tomography (SPET) (^99mTc-sestamibi and Thallium-201), gated blood pool imaging and coronary angiogram. There were 6 patients with single-vessel disease, 6 with two-vessel disease, 4 with three-vessel disease, 2 with coronary spasms, 1 with a patent graft and 1 with anginal episodes but a normal angiogram result. Three normal volunteers (2 women, 1 man; aged 24–26 years) also had rest and stress gated blood pool as well as rest and stress gated ^99mTc-sestamibi imaging. Rest and stress ^99mTc-ses-tamibi amplitude and phase images depicted regional myocardial wall shortening from the outer layer of the myocardium to the center of the left ventricle as follows a high amplitude halo of maximal negative count rate variaton; a circular thinner halo of negligible amplitude; a central region of maximal positive count rate variation, as the images evolved from end-diastole to end-systole. Similar patterns with regional differences represented abnormal myocardial wall shortening. (^99mTc-sestamibi and ²⁰¹T1 SPET) images were in agreement in 90% of the patients and 92% of myocardial regions. ²⁰¹T1 SPET detected 83% of angiographically proven lesions, as compared with 80% for ^99mTc-setamibi SPET and 80% for the amplitude images. The amplitude images demonstrated a larger number of other abnormalities not predicted on the angiogram, probably because they were able to detect regions with a potential for flow improvement and transient regional wall shortening abnormalities. Amplitude and phase analyses of gated rest and stress ^99mTc-ses-tamibi images are easy to perform and may become an important adjunct to (^99mTc-sestamibi SPET) images for a complete evaluation of both regional myocardial perfusion and regional contractile function using a single tracer. Offprint requests to: E.E. Camargo     

Quantitative analysis in single photon emission tomography (SPET)

Quantitative analysis can improve the sensitivity and specificity of single photon emission tomography (SPET) procedures, as well as reduce inter- and intraobserver variabilities. Quantification of the radioactivity distribution is the ultimate goal of SPCT. In this review we consider the basic requirements for an optimum three-dimensional reconstruction of the radionuclide distribution to enable quantification. Attenuation and scatter correction as well as varying resolution are the major problems. In the older SPET systems quantification was hampered by the lack of system sensitivity and sufficient computer power. Therefore, the imaging system was often assumed to be shift invariant and linear and the attenuation throughout the object uniform. More sophisticated solutions have been proposed and with more or less success implemented, but not for application in daily practice. Knowledge (measurement) of the attenuation is often required. New generation SPET systems employing multi-detectors and super minicomputers will ease the implementation of these solutions. Offprint requests to: J.A.K. Blokland     

Fluorine-18 deoxyglucose PET for assessment of viable myocardium in perfusion defects in 99mTc-MIBI SPET: a comparative study in patients with coronary artery disease

Extent and frequency of viable tissue in myocardial segments yielding a perfusion defect on technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI), single photon emission tomography (SPET) at rest was prospectively investigated with 2-¹⁸F-2-deoxyglucose (¹⁸FDG) positron emission tomography (PET) in 46 patients with chronic coronary artery disease (CAD). Of these, 43 had a history of old myocardial infarction. For comparative visual and quantitative evaluation of identical anatomical slices, PET image files were converted into the SPET file structure and into the same matrix size. SPET and PET images were documented and visually (9 segments/patient) or semiquantitatively evaluated by a target-like polar map. Relative perfusion was expressed in percentage of peak ^99mTc-MIBI uptake. Sample ¹⁸FDG uptake was related to the ¹⁸FDG uptake in the area of such maximal perfusion (¹⁸FDG uptake was 100% at the 100% ^99mTc-MIBI uptake area). Of 414 segments, 167 (40%) revealed a resting perfusion defect. ¹⁸FDG uptake was present in 38 (23%) of the defects, while another 40 (24%) segments yielded ¹⁸FDG uptake in the periphery of the defect. When grouped according to the degree of ^99mTc-MIBI uptake-reduction (in percentage of peak activity), 80% of severe defects (30% of peak uptake), 48% of moderate (31%–50% of peak uptake) and 31% of mild (>50% of peak uptake) defects were considered as non-viable on the basis of ¹⁸FDG uptake. Complete viability was found in none of the severe defects in contrast to 29% of moderate and 35% of mild perfusion defects. From these data we conclude that ^99mTc-MIBI uptake as a myocardial perfusion marker underestimates myocardial viability in patients with chronic CAD and after myocardial infarction. Nevertheless, only moderate reductions of ^99mTc-MIBI uptake seem to imply a greater likelihood for viability. Comparative analysis of metabolism and flow is possible with different tomographic systems and is valuable for clinical evaluation of the cardiac patient. Offprint requests to: C. AltehoeferThis paper presents in part results of the doctoral thesis of C. Feinendegen and was supported in part by the EEC Concerted Action on PET in Cardiology.It is dedicated to Prof. L.E. Feinendegen, Jülich/Düsseldorf on the occasion of his 65th birthday.     

The significance of a dipyridamole induced 99mTc-MIBI perfusion abnormality on single photon emission tomography: a quantitative validation with labelled water and positron emission tomography

To relate technetium-99m 2-methoxy-isobutylisonitrile (^99mTc-MIBI) uptake to regional myocardial blood flow (rMBF), ^99mTc-MIBI single photon emission tomography (SPET) and H₂ ¹⁵O positron emission tomography (PET) scans were obtained at rest and after dipyridamole infusion in six patients with single vessel coronary artery disease. ^99mTc-MIBI and H₂ ¹⁵O data sets were created for each segment perfused by the stenotic vessel and for a normal reference area, assigning regions on the SPET tomograms to comparable regions on the PET by similar transaxial image reconstructions. All patients demonstrated post-dipyridamole ^99mTc-MIBI perfusion defects in the territories supplied by the stenotic arteries. Resting rMBF in these regions was slightly lower than that in the normal areas (0.82±0.05 vs 0.90±0.09 ml/g/min, P=NS). A 43%±14% reduction in ^99mTc-MIBI activity in the area at risk was coupled with on average a 60%±9% reduction in post-dipyridamole rMBF compared with control regions (0.98±0.08 vs 2.52±0.51 ml/g/min, P<0.001). Thus, SPET assessment of ^99mTc-MIBI uptake tends to underestimate the perfusion contrast between areas with normal and areas with low coronary vasodilatory reserve when compared to PET. However, these findings may still not affect the clinical usefulness of ^99mTc-MIBI and more extensive studies are required to confirm these results in the clinical environment.     

Technetium-99m hexamethylpropylene amine oxime single photon emission tomography in febrile convulsions

We report our initial experience with technetium-99m hexamethyl propylene amine oxime (^99mTC-HMPAO) brain single photon emission tomography (SPET) in the investigation of 19 children presenting with febrile convulsions. Two patients with complex febrile convulsions showed focal SPET lesions contralateral to the neurological deficit. However, in 9 out of 17 patients with simple febrile convulsions, focally disturbed perfusion was shown. In 4 out of 6 patients with electroencephalogram (EEG) abnormalities on admittance, SPET revealed at least 2 focal lesions. The temporofrontal region was the one most commonly involved. The SPET findings presented here also suggest a temporal relationship with the febrile convulsions, with markedly fewer lesions if examined after 12 days. In our initial experience, perfusion SPET did not show any particular pattern helpful in the differential diagnosis of the child presenting with febrile convulsions. Physiopathologically, our findings may support the hypothesis that brain tissue is regionally more vulnerable to fever, in patients presenting with febrile convulsions.     

Comparison of thallium-201 and technetium-99m teboroxime myocardial single photon emission tomography with coronary arteriography

Myocardial single photon emission tomography (SPET) using technetium-99m teboroxime (teboroxime) was studied and the results compared with those of thallium-201(thallium) SPET and coronary arteriography in 19 patients. Resting teboroxime SPET was performed initially. Two hours later, exercise teboroxime SPET was performed. Exercise ergometer tests for both teboroxime and thallium were carried out in a supine position. The levels of exercise achieved for both tests were similar. Agreement for the identification of myocardial segments between thallium SPET and teboroxime SPET was 147/171(86%) (NS). When a significant stenosis was defined as 75% or 50%, agreement between two radiopharmaceuticals for the detection of diseased vessels was 89% (NS, = 0.601) or 88% (NS, = 0.713), respectively. In only 2/19 cases were inferior and posterior segments (3/171) difficult to interpret in teboroxime SPET due to hepatic activity. Thus, teboroxime SPET with a short data acquisition time resulted in a rapid completion for each study and had a good correlation with thallium SPET. Offprint requests to: M. Oshima, M.D., Ph.D. Department of Radiology Nagoya First Red Cross Hospital     

Visualization of posture-dependent cerebral blood flow in a patient with Takayasu's disease by means of 99mTc-HMPAO brain single photon emission tomography

A case of Takayasu's disease in a 22-year-old woman who complained of severe fainting attacks is presented. Bilateral obstruction of the cervical arteries was confirmed by digital subtraction angiography. Preoperative technetium-99m hexamethylpropylene amine oxime brain SPET in the sitting position showed bilateral hypoactivity in the temporoparietal areas. Subtraction brain SPET showed slightly increased activity in the lying position. The patient has had no fainting attacks since bypass surgery. Postoperative ^99mTc-HMPAO brain SPET in the sitting position showed normal activity except in the right temporoparietal area. This area was filled in the lying position. ^99mTc-HMPAO brain SPET is the only technique that can visualize the cerebral blood flow in any position, this capability deriving on the fact that the distribution of ^99mTc-HMPAO in the brain is fixed in the first 2–3 min following injection. The use of both sitting and lying ^99mTc-HMPAO brain SPET is very useful for detecting an abnormality (i.e. an inhomogeneous response due to the fall in perfusion pressure) that could not be seen if the cerebral blood flow were to be assessed only in the lying position. Correspondence to: K. Hayashida     

A comparative technetium 99m hexamethylpropylene amine oxime SPET study in different types of dementia

Regional cerebral perfusion was evaluated by single photon emission computed tomography (SPET) using technetium 99m hexamethylpropylene amine oxime (^99mTc-HMPAO) as a tracer, in 13 control subjects and 44 age-matched patients suffering from dementia of the Alzheimer's type (DAT, n=19), presumed Pick's disease (n=5), idiopathic Parkinson's disease with dementia (DPD, n=15) and progressive supranuclear palsy (PSP, n=5). HMPAO uptake was measured in the superior frontal, inferior frontal, parietal, temporal and occipital cortices, and the perfusion values were expressed as cortical/cerebellar activity ratios. As compared with controls, tracer uptake ratios in the DAT group were significantly reduced over all cortical regions, with the largest defects in the parieto-temporal and superior frontal cortices. A marked hypoperfusion affecting the superior and inferior frontal cortices was found in Pick's disease, whereas a mild but significant hypoperfusion was observed only in the superior frontal cortex of patients with PSP. In the DPD group, HMPAO uptake was significantly reduced in the parietal, temporal and occipital cortices, but not in the frontal cortex. These results show that DAT and DPD share an opposite anteroposterior HMPAO uptake defect as compared with the Pick's and PSP groups. Offprint reprints to: M.O. Habert     

Effectiveness of planar image and single photon emission tomography of thallium-201 compared with gallium-67 in patients with primary lung cancer

A comparative study of planar images and single photon emission tomography (SPET) of thallium-201 chloride and gallium-67 citrate was performed in 38 patients with proven primary lung cancer to detect the primary lung tumour and to establish the presence of metastasis in the lung hilum and mediastinum. The findings of planar images and SPET were compared with the pathological findings after thoracotomy. It was shown that ²⁰¹Tl studies were superior to ⁶⁷Ga studies for evaluation of the primary lesion and lymph node metastases. Offprint requests to: S. Matsuno, M.D.     

Myocardial perfusion damage after mediastinal irradiation for Hodgkin's disease: a thallium-201 single photon emission tomography study

Conflicting data have been reported on the incidence of myocardial abnormalities after mediastinal irradiation for Hodgkin's disease. We studied myocardial perfusion in 31 clinically asymptomatic patients (13 male, 18 female, mean age 35 years) 7 years (range 3–11 years) after mantle field radiotherapy. Thallium-201 tomoscintigraphic data were obtained after exercise, 4 h later and at rest (8–15 days later). Images were analysed visually and quantitatively (sectorial quantification of ²⁰¹T1 uptake on the bull's eye images of the short-axis slices) compared with those of 35 subjects with a low likelihood of coronary artery disease. Twenty-five tomographic data sets were available. Images were visually abnormal in 21 patients (84%) showing an heterogeneous ²⁰¹Tl uptake. In 68%, the sectorial ²⁰¹Tl uptake was lower than the mean ²⁰¹Tl uptake value minus 2 standard deviations measured in subjects with a low likelihood of coronary artery disease. Significant redistribution (quantitatively assessed 10%) was present in 10 patients (40%). In most of the patients, the location and the shape of the defect(s) could not be anatomically related to an epicardial coronary vessel disease. These results indicate that after mediastinal irradiation the ²⁰¹Tl myocardial uptake is frequently abnormal. The observed patterns suggest a disease of the small coronary vessels and/or the existence of a myocardial fibrosis rather than epicardial coronary artery disease.     

Technetium-99m tetrofosmin single photon emission computed tomography to detect metastatic papillary thyroid carcinoma in patients with elevated human serum thyroglobulin levels but negative I-131 whole body scan

AIM: The aim of this study was to evaluate the effectiveness of technetium-99m tetrofosmin (Tc-99m TF) single photon emission computed tomography (SPECT) of the neck and chest to detect metastatic lesions in papillary thyroid carcinoma (PTC) after near total thyroidectomy and radioiodine (I-131) treatment in patients who present with elevated serum human thyroglobulin (hTg) levels but negative I-131 whole body scan (WBS). MATERIALS AND METHODS: Twenty patients with PTC treated by near total thyroidectomy and I-131 treatments were included in this study. All 20 patients had negative I-131 WBS results and elevated hTg levels (hTg 2.0 microIU/ml) under thyroid-stimulating hormone (TSH) stimulation (TSH 30 microIU/ml). Nineteen of the 20 cases were confirmed to have metastases by operation/biopsy histopathological findings or clinical follow-up longer than 1 year by additional morphological imaging techniques. The remaining patient has been followed up closely and has been disease free for 10 months. Tc-99m TF SPECT was performed to detect metastatic lesions. RESULTS: Tc-99m TF SPECT demonstrated lesions in 11/19 patients; a sensitivity of 57.9%. Tc-99m TF SPECT failed to demonstrate lesions in eight patients including smaller lymph nodes and miliary lung metastases. CONCLUSIONS: We conclude that Tc-99m TF SPECT is a useful additional tool to detect metastatic lesions in PTC with elevated hTg but negative I-131 WBS. However, smaller lymph nodes and miliary lung metastases may be missed.     

Myocardial technetium-99m sestamibi single-photon emission tomography as a prognostic tool in coronary artery disease: multivariate analysis in a long-term prospective study

To date several studies have evaluated the accuracy of thallium-201 myocardial scan in risk stratification of coronary artery disease (CAD), while reports using technetium-99m methoxyisobutylisonitrile (MIBI), a tracer particularly suited to single-photon emission tomographic (SPET) imaging, are lacking. To rectify this omission, a prospective study was started in 1988 and at present 176 consecutive, and thus unselected, patients have been enrolled. All of them have been submitted to stress-rest MIBI SPET for the diagnosis or evaluation of CAD; 147 patients (121 males and 26 females, aged 53±9 years) have completed a surveillance period of at least 36 months following the scintigraphic study (range 36–60 months, mean 43). Sixty-one patients had a documented previous myocardial infarction. The mean pretest likelihood of CAD was 44% in the patients without prior infarction. The main anamnestic, clinical, EKG and scintigraphic findings were evaluated and statistically correlated with the incidence of ensuing cardiac events using both univariate (chi-square test) and multivariate analysis (logistic regression model). Twenty-nine patients suffered from a cardiac event during the follow-up period (i.e. three cardiac deaths, six myocardial infarctions and 20 cases of unstable angina). Statistical multivariate analysis identified MIBI scan as the only highly significant and independent prognostic predictor [P=0.006, relative risk (RR)=17.62]. In detail, the most important scintigraphic parameters were the presence of a reversible defect (P=0.0089, RR=5.11) and the extension of the stress perfusion defect (P=0.0255, RR=3.27). The presence of typical angina proved to be a slightly significant predictor (P=0.051, RR=2.45), while no other examined parameter showed a significant correlation with a bad prognosis. In conclusion, MIBI SPET can be considered a useful tool in the risk stratification of CAD patients. The presence of a reversible perfusion defect or an extensive defect appears responsible for a clear increase in the probability of subsequent cardiac events, thus indicating a more aggressive therapeutic approach to be appropriate.This work was presented in part at the 6th World Congress of the World Federation of Nuclear Medicine and Biology in Sydney, Australia (28–30 October 1994).     

门控心肌灌注显像局部室壁运动异常判断冠状动脉狭窄程度的价值

目的 探讨99mTc-甲氧基异丁基异腈(99mTc-MIBI)门控心肌灌注显像出现的可逆性局部室壁运动异常(RWMA)在判断冠状动脉狭窄程度中的价值。方法 入选90例疑似冠心病患者,在门控心肌灌注显像的前后2周内进行冠状动脉造影检查。门控心肌SPECT检查应用9节段5分制进行室壁运动及增厚率评分。结果 心肌显像上可逆性RWMA判断≥75%的冠状动脉狭窄的灵敏度为64%,特异度为95%;用可逆性RWMA来区别严重冠状动脉狭窄(≥75%)和不严重的冠状动脉狭窄(<75%)有很高的阳性预测值(97%)。可逆性RWMA和濒危冠状动脉评分之间有良好的相关性。多因素分析显示,负荷室壁负荷总积分、室壁负荷差分值和心电图负荷试验阳性是濒危冠状动脉积分的独立危险因子。结论 根据99mTc-MIBI门控心肌灌注显像上可逆性RWMA判断严重冠状动脉狭窄具有高度的特异性和阳性预测值。潘生丁负荷后及可逆性RWMA增强了心肌灌注显像对冠状动脉狭窄程度的评估。