Validation of a model of left ventricular segmentation for interpretation of SPET myocardial perfusion images

Several models of left ventricular segmentation have been developed that assume a standard coronary artery distribution, and are currently used for interpretation of single-photon emission tomography (SPET) myocardial perfusion imaging. This approach has the potential for incorrect assignment of myocardial segments to vascular territories, possibly over- or underestimating the number of vessels with significant coronary artery disease (CAD). We therefore sought to validate a 17-segment model of myocardial perfusion by comparing the predefined coronary territory assignment with the actual angiographically derived coronary distribution. We examined 135 patients who underwent both coronary angiography and stress SPET imaging within 30 days. Individualized coronary distribution was determined by review of the coronary angiograms and used to identify the coronary artery supplying each of the 17 myocardial segments of the model. The actual coronary distribution was used to assess the accuracy of the assumed coronary distribution of the model. The sensitivities and specificities of stress SPET for detection of CAD in individual coronary arteries and the classification regarding perceived number of diseased coronary arteries were also compared between the two coronary distributions (actual and assumed). The assumed coronary distribution corresponded to the actual coronary anatomy in all but one segment (#3). The majority of patients (80%) had 14 or more concordant segments. Sensitivities and specificities of stress SPET for detection of CAD in the coronary territories were similar, with the exception of the RCA territory, for which specificity for detection of CAD was better for the angiographically derived coronary artery distribution than for the model. There was 95% agreement between assumed and angiographically derived coronary distributions in classification to single- versus multi-vessel CAD. Reassignment of a single segment (segment #3) from the LCX to the LAD territory further improved the model's fit with the anatomic data. It is concluded that left ventricular segmentation using a model with assumed coronary artery distribution is valid for interpretation of SPET myocardial perfusion imaging.     

Myocardial distribution of (18)F-FDG and (99m)Tc-sestamibi on dual-isotope simultaneous acquisition SPET compared with PET

A dual-isotope simultaneous acquisition (DISA) single-photon emission tomography (SPET) protocol with fluorine-18 fluorodeoxyglucose ((18)F-FDG) and a technetium-99m labelled flow tracer is attractive because it permits assessment of both myocardial glucose utilisation and flow within a single study. Differences in physical and physiological characteristics between (18)F-FDG and the (99m)Tc-labelled flow tracer, however, may cause differences in myocardial activity distribution between the agents. The aim of this study was to investigate the relation between the myocardial distribution of (18)F-FDG and a (99m)Tc-labelled flow tracer on DISA SPET in comparison with nitrogen-13 ammonia/(18)F-FDG positron emission tomography (PET). Nine normal volunteers without cardiac disease and ten patients with known coronary artery disease (CAD) underwent (13)N-ammonia/(18)F-FDG PET and (99m)Tc-sestamibi/(18)F-FDG DISA SPET. Using a semiquantitative polar map approach, the left ventricular myocardium was divided into nine segments, and relative regional activity was calculated for each segment. A segment was considered to have concordant uptake between (18)F-FDG and flow tracer if the difference in measured regional activity between the tracers was < or =10% of peak activity, and the percentage of concordant segments was calculated for each subject. There was a good overall concordance of myocardial activity between the agents on DISA SPET (84.0%+/-14.8%) in normals, which was comparable to that seen on PET (86.4%+/-14.5%, NS vs DISA SPET). However, the myocardial activity distributions of (18)F-FDG and flow tracer were not identical in that reduced flow tracer activity was seen in the basal segments on DISA SPET in both normals and CAD patients. It is concluded that there is good overall concordance of activity between (18)F-FDG and flow tracer in normal myocardium on DISA SPET, which is comparable to that on PET, supporting the use of combined (99m)Tc-flow tracer/(18)F-FDG imaging for the detection of viable myocardium. However, there is a difference in the myocardial activity distribution between the agents in both normals and CAD patients, the difference being particularly evident in the basal segments. Therefore, careful image interpretation that takes into consideration the different normal activity distribution between the tracers and/or a tracer-specific normal database is necessary for comparison with patient studies.     

门控~（99m）Tc－MIBI心肌断层显像诊断多支冠状动脉病变和心肌缺血

目的：评价门控心肌显像诊断冠心病（ＣＡＤ）的临床意义。方法：对３２例ＣＡＤ患者的９９ｍＴｃ—甲氧基异丁基异腈（ＭＩＢＩ）门控。非门控心肌断层显像和冠状动脉造影进行了比较，以及对４０例ＣＡＤ患者的门控与常规潘生丁─静息心肌断层显像也作了比较。结果：１．门控与非门控显像法诊断ＣＡＤ的灵敏度和特异性无差别，但前者对检测病变冠状动脉和诊断多支冠状动脉病变性ＣＡＤ的灵敏度高于后者，而特异性无差别。２．射血分数（ＥＦ）值显著影响非门控图像的病变显示。３．与非门控显像比较，门控显像能观察到更多的再分布节段和较少的无再分布节段。静息门控心肌显像除发现较多的灌注异常外，还观察到了许多单纯收缩功能受损节段。后者虽然可判断８４％的灌注再分布节段，但特异性不高。结论：门控心肌断层显像对诊断ＣＡＤ无优势，但对诊断ＥＦ值较高的或多支冠状动脉病变性ＣＡＤ、检测病变冠状动脉和心肌缺血有一定价值。     

Coregistered MR imaging myocardial viability maps and multi-detector row CT coronary angiography displays for surgical revascularization planning: initial experience

PURPOSE: To evaluate assignment of left ventricular (LV) myocardial segments to coronary arterial territories by using coregistered magnetic resonance (MR) imaging and multi-detector row computed tomography (CT) displays; to assess the accuracy of coregistered displays in determining the distribution of clinically important coronary artery disease (CAD) and regional effect of CAD on LV myocardium in patients with chronic ischemic heart disease (CIHD); and to determine the utility of coregistered displays in optimizing surgical revascularization planning. MATERIALS AND METHODS: This study was HIPAA compliant and was approved by the local Institutional Review Board, with waiver of informed consent. Twenty-six patients (19 men, seven women; age, 56 years +/- 12 [+/- standard deviation]) with CIHD underwent MR imaging assessment of myocardial viability and multi-detector row CT assessment of CAD on the same day. For coregistration, a population-based LV model was fit to each data set separately; models were then registered spatially. For data analysis, correspondence between coregistered displays and the 17-segment LV model for assessment of CIHD was evaluated, accuracy of using coregistered displays to evaluate the extent of CAD and myocardial disease was assessed, and utility of coregistered displays in optimizing surgical revascularization planning was determined. RESULTS: Coronary assignment for coregistered displays and the 17-segment LV model differed in 17% of myocardial segments. For the majority of patients, three segments (midanterolateral [62%], apical lateral [73%], and apical inferior [58%]) were discordant. Segments were supplied by the left anterior descending artery, a diagonal branch, or a ramus intermedius with diagonal distribution in all but one case. Coregistered displays were deemed concordant with selective coronary angiography and alternate myocardial imaging in all cases. Overall, surgical planning was potentially enhanced in 83% of cases because, compared with alternate imaging modalities, coregistered displays were believed to demonstrate the relationship between coronary arteries and underlying myocardial tissue more definitively and efficiently (for patients in whom surgery was performed) or more correctly and comprehensively (for a presumably better-tailored surgery). CONCLUSION: Assessment of CIHD can be improved by using coregistered displays that directly relate the condition of LV myocardium to the anatomy of the coronary arteries in individual patients.     

Exercise gated planar myocardial perfusion imaging using technetium-99m sestamibi for the diagnosis of coronary artery disease: an alternative to exercise tomographic imaging

Single-photon emission tomography (SPET) using technetium-99m labelled myocardial tracers (e.g.^99mTc-sestamibi) has become one of the most popular myocardial imaging methods for the diagnosis of coronary artery disease (CAD). This prospective study was designed to evaluate the diagnostic performance of^99mTc-sestamibi exercise gated planar myocardial imaging by comparison with both visual and quantitative analyses of SPET. The study was conducted in 115 consecutive patients with known or suspected CAD, including 54 patients with a previous myocardial infarction (MI), referred for exercise testing prior to coronary angiography. Multi-gated planar imaging and SPET were performed after bicycle exercise. The end-diastolic (ED) and SPET images were visually scored (SVi). Myocardial uptake was quantitated on SPET slices using maximum count circumferential profiles (SQu) and defect extent was measured by comparison with gender-matched data sets obtained from 27 controls (<5% likelihood of CAD). CAD was defined as coronary artery stenosis >50% and/or regional wall motion abnormality. The cut-off criteria for positivity of the three procedures were determined from receiver operating characteristic (ROC) curves derived from the data of patients without previous MI. The area under the ROC curves was similar for ED, SVi and SQu. This was confirmed by the analysis of sensitivity performed using the ROC curve-derived cut-off criteria, in patients with or without previous MI. SVi was more sensitive than ED in identifying the diseased vessel(s) (ED: 41% vs SVi: 80%;P<0.0005) but ED was more specific in this respect (ED: 79% vs SVi: 61%;P<0.0005). We conclude that visual analysis of ED images obtained from gated^99mTc-sestamibi stress planar imaging is a valuable alternative to SPET imaging for the diagnosis of CAD. SPET is, however, more accurate for the evaluation of the disease extent and localization and therefore remains the method of choice for the assessment of myocardial perfusion.     

99m Tc-MIBI心肌显像对冠状动脉病变的定位研究

目的：探讨９９ｍＴｃ－ＭＩＢＩ心肌显像在检出冠心病病变心肌节段和病变血管定位上的价值。方法：对照分析２０例冠心病和５例对照组冠状动脉造影与９９ｍＴｃ－ＭＩＢＩ单光子发射断层显像（ＳＰＥＣＴ）的结果。结果：潘生丁负荷ＳＰＥＣＴ检出冠心病、病变血管和病变心肌节段的敏感性分别为９５．００％、６３．６４％和４３．６８％明显高于静息相的６０．００％、４２．４２％和２７．５９％（Ｐ＜０．０１）。与静息相比较,潘生丁负荷ＳＰＥＣＴ多发现３３．３３％的病变血管和３６．８４％的病变心肌节段。对病变血管的敏感性,ＬＡＤ高于ＲＣＡ和ＬＣＸ;对于病变心肌节段检测敏感性ＲＣＡ支配节段高于ＬＡＤ和ＬＣＸ,特异性均较高。结论：潘生丁ＳＰＥＣＴ能显著提高冠心病的检出,有效估计病变心肌范围和病变冠状动脉     

Attenuation correction by simultaneous emission-transmission myocardial single-photon emission tomography using a technetium-99m-labelled radiotracer: impact on diagnostic accuracy

Irregular photon attenuation may limit the diagnostic accuracy of myocardial single-photon emission tomography (SPET). The aim of this study was to quantify the potential benefit of attenuation correction by simultaneous emission and transmission imaging for the detection of coronary artery disease (CAD) of vessels supplying the inferoposterior wall segments. In 25 male patients with 50% stenoses of the right coronary artery and/or circumflex artery but without significant narrowing of the left anterior descending artery, stress studies using technetium-99m tetrofosmin (400 MBq) were carried out with and without attenuation correction. A dual-head camera with L-shaped detector positioning was equipped with two scanning gadolinium-153 line sources. Tomograms were reconstructed and quantified using circumferential count rate profiles of myocardial activity (two in each patient). The profiles were compared with the respective normal ranges obtained from a database of 25 male patients with a <10% likelihood of CAD. In patients without CAD, the maximal differences in count density of different wall segments were reduced from 29.0% in non-corrected (NC) studies to 9.5% in attenuation-corrected (AC) studies. In particular, the inferoposterior and septal wall segments were represented by significantly increased relative count densities after attenuation correction. The effects of attenuation correction proved independent of body mass. In patients with CAD, segmental count densities were abnormal in 84% of the NC studies and 100% of the AC studies. In single-vessel disease the stenotic vessel was identified in 66% of cases by NC studies and in 100% by AC studies. In AC studies, the extent and depth of defects exceeded those in NC studies. For the detection of CAD of the right coronary artery, the receiver operating characteristic (ROC) curves relating to the AC studies demonstrated improved discrimination capacity (P<0.05). ROC analysis of CAD detection yielded normalcy rates of 82% (NC) and 94% (AC) for the circumflex artery and 65% (NC) and 97% (AC) for the right coronary artery area at a sensitivity level of 95%. It is concluded that attenuation correction using the above system may enhance the diagnostic accuracy of myocardial SPET when inferoposterior wall segments are to be evaluated.     

Comparison of 99mTc-sestamibi lung/heart ratio, transient ischaemic dilation and perfusion defect size for the identification of severe and extensive coronary artery disease

The ability to identify patients with severe coronary artery disease (CAD) by analysis of perfusion defects is limited. The lung/heart ratio (LHR) and transient ischaemic dilatation (TID) have been used for this purpose in thallium-201 scintigraphy. The value of these parameters in technetium-99m sestamibi single-photon emission tomography (SPET) imaging is controversial. In this study, therefore, we determined TID and LHR in a single-day rest/stress 99mTc-sestamibi SPET perfusion protocol and compared these measurements with perfusion defect size (PDS) and angiographic severity of CAD. Severe CAD was defined as >75% left main coronary stenosis and/or >90% proximal left anterior descending artery stenosis and/or >90% proximal stenosis in the left circumflex and right coronary arteries. LHR was determined from a stress anterior planar image recorded < or =6 min after exercise. TID ratio was derived from automatically calculated left ventricular rest/stress volumes, and PDS was measured based on semi-automated computer software (CEqual). Diagnostic accuracy and predictive values were compared between 22 patients with severe and 98 patients without severe CAD. LHRs showed a higher sensitivity (73%) for the assessment of severe CAD as compared to PDS and TID ratio (41% and 23% respectively, P<0.01), whereas specificity was highest for TID ratio [95%, P<0.01 when compared to PDS (84%) and LHR (82%)]. It is concluded that increased LHR in 99mTc-sestamibi myocardial perfusion imaging seems to yield good diagnostic accuracy in the detection of patients with severe CAD and may be derived from a single-day rest/stress study.     

Diagnostic significance of myocardial perfusion scintigraphy in identification and localisation of culprit lesions in patients undergoing elective PTCA

BACKGROUND/AIM: The coronary angiography provides information on the anatomical state of the coronary tree, while myocardial perfusion scintigraphy (MPI) facilitates the evaluation of the grade of ischaemia that a particular stenosis produces. The purpose of MPI is to detect the coronary stenosis that provokes the ischaemia and is termed the "culprit lesion". The aim of this study was to evaluate the accuracy of 1-day DypEX 99mTc-tetrofosmin tomography in the identification and localization of culprit lesion in the patients with known coronary artery disease (CAD). METHODS: Ninety-one (91) patients with known CAD were studied. In all of them significant coronary narowing (> 75% luminal stenosis) was angiographically detected. All the patients were submitted to 2 i.v. injections of 99mTc-tetrofosmin, one in a peak of pharmacologic dipyridamole stress protocol with concomitant low level bicycle exercise 50W (DypEX) and the other 3 h after exercise. Quantification of regional tetrofosmin uptake was performed using short-axis myocardial tomogram that was divided on 17 segments for each study. Reversibility score (RS) > or =3 determinated culprit lesion. Two of segments with scor 5 (index of reversibility scor--IRS) in the territory of coronary artery stenoses determinated culprit lesion. RESULTS: A total of 273 vascular territories (4641 segments) were analyzed before percutaneous coronary intervention (PCI). Overall sensivity, specificit, and accuracy using RS > or =3 and IRS were 90.1%, 87.1%, 89.4%, with positive predictive value 95.8%, and 94.1%, 93.3%, 94%, with positive predictive value 98%, respectively. CONCLUSION: RS and IRS significantly improve sensitivity, specificity, and accuracy for determination of culprit lesion in patients undergoing PCI.     

Perfusion impairment in patients with normal-appearing coronary arteries: identification with contrast-enhanced MR imaging

PURPOSE: To prospectively determine the feasibility of using first-pass magnetic resonance (MR) imaging to distinguish between myocardial segments in patients with coronary artery disease (CAD) of different degrees of obstruction and those in patients with normal-appearing coronary arteries. MATERIALS AND METHODS: The study was approved by the institutional ethics committee, and all patients provided informed consent. First-pass contrast material-enhanced MR imaging was performed at rest and after the infusion of dipyridamole in 37 patients (29 men, eight women; mean age, 57.2 years +/- 10.5 [standard deviation]) who had positive exercise test results or a clinical history of CAD. Myocardial segments were divided into five groups according to the degree of obstruction in the supplying artery. Signal intensity upslope, peak signal intensity, and time to peak signal intensity, as well as hyperemia-to-rest (HR) ratios for each of these three variables, were analyzed for each segment by using a generalized linear model. RESULTS: Signal intensity upslope in patients with normal coronary arteries at angiography was significantly higher than that in patients with CAD (P < .001). Signal intensity upslope for segments in patients without CAD was significantly different from that for normal-appearing segments in patients with CAD (P < .001). Signal intensity upslope (P < .05) and peak signal intensity (P < .01) enabled the differentiation of segments with more than 70% reduction in luminal diameter from those in all other groups. HR ratios demonstrated findings that were similar to those obtained by using each signal intensity variable alone. CONCLUSION: First-pass MR imaging can be used to distinguish segments with different degrees of obstructive CAD. Importantly, MR imaging can help identify segments with impaired perfusion and normal-appearing coronary arteries in patients with CAD and can demonstrate obstructive lesions in other territories.     

Detection of moderate and severe coronary artery stenosis with technetium-99m tetrofosmin myocardial single-photon emission tomography

The aim of this study was to determine the diagnostic accuracy of technetium-99m tetrofosmin myocardial imaging for the localization of coronary artery stenoses of different degrees of severity. Stress-rest single-photon emission tomography (SPET) was performed on separate days in 80 patients (64 males, 16 females; mean age 61 years; 43 patients with previous myocardial infarction; 18 patients with pharmacological stress), within 6 months of coronary angiography. Scintigraphic images were blindly and independently evaluated by three observers. Coronary stenosis was defined as a >50% narrowing in luminal diameter; severe stenosis was defined as a proximal stenosis of >75% or a peripheral stenosis of >90%. Coronary angiography revealed normal coronary arteries or insignificant coronary stenosis in 13 patients and significant coronary stenoses in 67 patients. The sensitivity and specificity of ^99mTc-tetrofosmin SPET in respect of severely stenosed vessels were, respectively, 80% and 65% for the left anterior descending artery (LAD), 100% and 46% for the right coronary artery (RCA) and 58 and 78% for the left circumflex artery (LCx) territories. Considering all the significantly stenosed vessels, a significant decrease in sensitivity was observed for LAD territories (to 59%, P=0.05), and a nonsignificant decrease for RCA (88%) and LCx (47%) territories while specificity values remained essentially unchanged. No significant changes in sensitivity or specificity were observed when regions with previous myocardial infarction were excluded. In conclusion, the sensitivity of ^99mTc-tetrofosmin SPET for the localization of individual stenosed vessels is only moderate when all significant stenoses are considered, but the ability of this technique to predict the location of severe coronary artery stenoses seems satisfactory, with the exception of the low specificity in respect of RCA territories. Received 26 April and in revised form 7 June 1997     

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-sestamibi 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 variation; 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 201Tl SPET images were in agreement in 90% of the patients and 92% of myocardial regions. 201Tl 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.(ABSTRACT TRUNCATED AT 250 WORDS)     

电子束CT检出冠状动脉钙化及其与心肌灌注显像的对比研究

目的比较电子束ＣＴ（ＥＢＣＴ）检查冠状动脉钙化（ＣＡＣ）及核素心肌灌注显像（ＭＰＩ）评价冠心病（ＣＨＤ）的价值。材料与方法本组５０例均为临床疑诊或确诊为ＣＨＤ患者。所有患者均行ＥＢＣＴ、ＭＰＩ及冠状动脉造影。结果４０例患者共８４支血管冠状动脉造影证实有明显的冠状动脉病变（ＣＡＤ）（狭窄＞５０％），其中１４例为单支病变，８例为双支病变，１８例为三支病变，另有１０例冠状动脉造影正常。ＥＢＣＴ预测ＣＡＤ的敏感性、特异性及准确性为８３％、８０％及８２％，ＭＰＩ预测ＣＡＤ的敏感性、特异性及准确性分别为８５％、８０％及８４％，ＥＢＣＴ与ＭＰＩ的结果间无显著性差异（Ｐ＞０．０５）。ＣＡＣ血管供血区出现心肌缺血者达６５％。结论ＣＡＣ是预测ＣＡＤ的有价值指标。在有症状的人群中ＥＢＣＴ检出ＣＡＣ预测ＣＡＤ的敏感性、特异性及准确性与ＭＰＩ相似。有症状人群中检出ＣＡＣ患者多有心肌缺血或梗死，因此为早期诊断冠心病，应对无症状人群进行筛选。     

静息态下冠状动脉狭窄对左室壁透壁心肌灌注影响的640层CT研究

目的确定静息态下透壁心肌灌注指数(TPR)的正常值,并探讨静息态下不同分支的冠状动脉狭窄与各冠状动脉分支的不同狭窄程度对左室壁不同节段TPR的影响。方法 274例患者行Toshiba 640层CT检查,包括冠状动脉CTA及左心室室壁CT灌注(CTP)检查。根据冠状动脉狭窄程度及17节段进行分组。计算正常组及不同冠状动脉狭窄程度组之间相应节段内TPR是否存在差异,以及冠状动脉狭窄程度与相应节段TPR的相关性。结果前降支及左旋支病变对于左室壁心肌灌注影响较为明显,前降支狭窄主要影响中间段前壁(r=-0.288)、心尖段前壁(r=-0.263)及中间段间隔壁(r=-0.196),左旋支主要影响基底部前侧壁(r=-0.241)、基底部后侧壁(r=-0.279)及心尖段侧壁(r=-0.201),而右冠状动脉病变影响较小,主要影响中间段后壁(r=-0.195);冠状动脉中、重度狭窄组对于左室壁心肌灌注影响程度较大(P<0.05),轻度狭窄影响较小;左室前壁心肌灌注最易受到冠状动脉狭窄影响;在静息状态下前降支供血区域组、左旋支供血区域组及右冠状动脉供血区域组正常心肌和重度狭窄心肌平均TPR值分别为1.14±0.09和1.07±0.13、1.13±0.11和1.06±0.14、1.15±0.14和1.10±0.12。结论不同冠状动脉分支狭窄分别可以影响不同节段的心肌透壁灌注;不同冠状动脉狭窄程度可以不同程度地影响心肌的TPR,二者具有相关性;静息状态下TPR正常值大于负荷状态下TPR。本研究提供了TPR静息态下的正常值。     

Dobutamine stress thallium-201 single-photon emission tomography versus echocardiography for evaluation of the extent and location of coronary artery disease late after myocardial infarction.

Dobutamine stress echocardiography and thallium-201 myocardial perfusion scintigraphy are clinically useful methods for the evaluation of coronary artery disease (CAD). However, the relative merits of these imaging modalities in the evaluation of the extent of CAD after myocardial infarction have not been well studied. The aim of this study was to compare the accuracy of dobutamine stress echocardiography and simultaneous 201Tl single-photon emission tomography (SPET) imaging for the diagnosis and localization of CAD late after acute myocardial infarction. Dobutamine (up to 40 micrograms kg-1 min-1)-atropine (up to 1 mg) stress echocardiography in conjunction with stress-reinjection 201Tl SPET was performed for the evaluation of myocardial ischaemia in 90 patients with previous myocardial infarction who underwent coronary angiography. Significant CAD was predicted on bases of myocardial ischemia (new or worsening wall motion abnormalities on echocardiography and reversible perfusion defects on 201Tl SPET). Significant CAD (> or = 50% luminal diameter stenosis) was detected in 73 (81%) patients. The sensitivity, specificity and accuracy of echocardiography in detecting remote ischaemia for the diagnosis of remote CAD (present in 53 patients) were, respectively, 79% (CI 70%-88%), 85% (CI 77%-93%) and 81% (CI 73%-90%), while the corresponding figures for 201Tl SPET were 75% (CI 66%-85%), 78% (CI 69%-87%) and 76% (CI 67%-86%) respectively (P = NS vs echocardiography). The sensitivity, specificity and accuracy of echocardiography in detecting peri-infarction ischaemia for the diagnosis of infarct-related artery stenosis (present in 70 patients) were, respectively, 77% (CI 68%-86%), 85% (CI 78%-92%) and 79% (CI 70%-87%) while the corresponding figures for 201Tl SPET were 73% (CI 64%-82%), 85% (CI 78%-92%) and 76% (CI 67%-84%) respectively (P = NS vs echocardiography). The agreement between the two methods for the diagnosis of peri-infarction and remote ischaemia was 70% (kappa = 0.37) and 80% (kappa = 0.59) respectively. It is concluded that dobutamine stress echocardiography and 201Tl SPET have comparable accuracy for the diagnosis of infarct related and remote CAD in patients with previous myocardial infarction. The agreement between the methods is higher for the diagnosis of remote CAD than for that of peri-infarction ischaemia.     

Simultaneous assessment of myocardial viability and function for the detection of hibernating myocardium using ECG-gated 99Tcm-tetrofosmin emission tomography: a comparison with 201Tl emission tomography combined with cine magnetic resonance imaging

The aims of this study were to evaluate the simultaneous assessment of myocardial viability and function for the detection of hibernating myocardium using ECG-gated 99Tcm-tetrofosmin single photon emission tomography (SPET), and to compare the technique with 201Tl SPET in combination with cine magnetic resonance imaging (MRI). Fifteen patients aged 41-70 years with impaired left ventricular function (mean LVEF 23.4 +/- 8.1%) and three-vessel coronary artery disease were studied before and after coronary artery bypass grafting (CABG). The following investigations were performed within the 3 months before surgery: stress/redistribution and separate-day rest 201Tl SPET with early and late imaging, stress and ECG-gated rest 99Tcm-tetrofosmin SPET, and resting cine MRI. Between 3 and 6 months post-surgery, stress/redistribution 201Tl SPET and cine MRI were repeated. Tracer uptake in nine segments of the left ventricle was graded visually and by quantitative analysis. Myocardial motion and thickening were graded visually from cine MRI and from gated 99Tcm-tetrofosmin SPET images. Segments were defined as hibernating pre-operatively if tracer uptake was moderately reduced or better but myocardial motion was severely hypokinetic or worse. The accuracy of pre-operative assessment was assessed by comparison with post-operative function assessed by MRI. The sensitivity and specificity for the prediction of functional improvement were 69% and 60% for late rest 201Tl uptake combined with MRI; 58% and 62% for rest 99Tcm-tetrofosmin uptake combined with MRI; and 62% and 45% when gated 99Tcm-tetrofosmin SPET was used to assess both tracer uptake and wall motion. In 21 of 135 segments, contractile function could not be assessed by gated 99Tcm-tetrofosmin SPET because of inadequate tracer uptake; function was improved in 5 (25%) of these segments after CABG. In conclusion, the combined assessment of viability and function using ECG-gated 99Tcm-tetrofosmin SPET is feasible and it allows the assessment of hibernating myocardium with similar accuracy to the combination of ungated 99Tcm-tetrofosmin SPET with MRI. Where tracer uptake is too poor for assessment of function, there is a low incidence of myocardial hibernation. However, ECG-gated 99Tcm-tetrofosmin SPET is not superior to 201Tl SPET combined with cine MRI in the identification of hibernation.     

Technetium-99m tetrofosmin rest/stress myocardial SPET with a same-day 2-hour protocol: comparison with coronary angiography A Spanish-Portuguese multicentre clinical trial

Technetium-99m tetrofosmin (Myoview) has unique properties for myocardial perfusion imaging very early after injection of the tracer. We used a very short same-day rest/stress protocol, to be performed within 2 h and evaluated its diagnostic accuracy. The study included 144 patients from seven Spanish and four Portuguese centres with a diagnosis of uncomplicated coronary artery disease (CAD); 78 patients (54%) had no history of prior myocardial infarction. Patients were injected with 300 MBq^99mTc-tetrofosmin at rest and 900 MBq approximately 1 h later at peak exercise. Single-photon emission tomographic (SPET) acquisitions were initiated within 5–30 min post injection. The results were compared with those of coronary angiography (CA). The data of 142 patients were completely evaluable (two with non-evaluable images were excluded). The quality of rest images was excellent or good in 86%, regionally problematic in 7%, poor but well interpretable in 5% and non-evaluable in 2%. The overall sensitivity for the detection of CAD was 93%, the specificity 38% and the accuracy 85%. The localization of defects by SPET in relation to the perfusion territories of stenosed vessels (50%) was achieved with a sensitivity of 64% for the left anterior descending artery, 49% for the left circumflex artery and 86% for the right coronary artery, and an accuracy of 71%, 72% and 73% respectively. Concordance of SPET and CA was 62% for single-vessel disease and 68% for multivessel disease. In conclusion, this Spanish-Portuguese multicentre clinical trial confirmed, in a considerable number of patients who underwent coronary angiography, the feasibility of^99mTc tetrofosmin (Myoview) rest/stress myocardial SPET using a very short protocol (2 h).The results contained herein were presented in part at the 2nd International Conference of Nuclear Cardiology, held in Cannes, France, on 23–26 April 1995     

Sensitivity,specificity and accuracy of stress SPECT myocardial perfusion imaging for detection of coronary artery disease in the distribution of first-order branch vessels,using an anatomical matching of angiographic and perfusion data

We sought to investigate the utility of stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the identification of coronary artery disease (CAD) in the distribution of first-order branch vessels. We evaluated 135 consecutive patients with coronary angiography and stress SPECT MPI. We anatomically matched angiography and SPECT to assess the sensitivity, specificity and accuracy of SPECT MPI for the detection of CAD in the distribution of first-order branches. Subgroup analysis for stress test performance and previous coronary artery bypass grafting (CABG) was also performed. The sensitivity, specificity and accuracy of stress SPECT MPI for the detection of CAD in the distribution of first-order branch vessels were all 67%. For isolated branch vessel CAD, stress SPECT MPI had a sensitivity of 44%. In patients without CABG, the sensitivity, specificity and accuracy for the detection of CAD in the distribution of first-order branch vessels were 71%, 67% and 68%, compared with 60%, 67% and 64% for patients with CABG. The sensitivity for isolated branch vessel CAD was 50% for patients without CABG, but only 29% for patients with CABG. The sensitivity and specificity for CAD in the distribution of branch vessels were similar for all patients for all stress test modalities and heart rate response (sensitivity, 64-69%; specificity, 61-69%). Stress SPECT MPI offers intermediate sensitivity, specificity and accuracy for the detection of CAD in the distribution of first-order coronary artery branch vessels. However, for isolated branch vessel CAD, stress SPECT has a lower sensitivity, particularly in patients with previous CABG.     

The additive value of gated SPET myocardial perfusion imaging in patients with known and suspected coronary artery disease

In myocardial perfusion scintigraphy, the clinical significance of fixed defects presents some difficulty. In this study, we evaluated whether additional information on left ventricular function assessed by quantitative gated single-photon emission computed tomography (gated SPET) would increase the diagnostic yield of the study in such patients. We studied 55 patients with a previous myocardial infarction and 20 patients without a previous myocardial infarction using gated SPET 99Tc(m)-tetrofosmin myocardial perfusion imaging. Each patient had to have a persistent perfusion defect consisting of at least three contiguous segments in the same vascular territory. The left ventricle was divided into 20 segments which were analysed for perfusion and wall thickening on a 4-point severity scale. Of the 55 patients with myocardial infarction, 19 (35%) patients showed preserved wall thickening in the region of the previous infarction with fixed perfusion abnormalities, which suggested residual myocardial viability. In the 20 patients without myocardial infarction, preserved wall thickening was seen in 10 (50%) patients with fixed perfusion defects, suggesting an attenuation artefact. Conversely, in 16 (29%) patients in the myocardial infarction group and two (10%) patients in the non-myocardial infarction group normal perfusion was associated with severely diminished wall thickening possibly due to stunning. We found an excellent correlation between wall thickening and left ventricular ejection fraction both for the patients with myocardial infarction and the patients without myocardial infarction (r = 0.86 and r = 0.82, respectively, both P<0.0001). A reasonable correlation between perfusion and left ventricular ejection fraction was found for the patients with myocardial infarction (r = 0.41, P = 0.002), and a non-significant correlation for the patients without myocardial infarction (r = 0.37, P = 0.1). Quantitative gated SPET myocardial imaging allows the detection of residual wall thickening in patients with a previous myocardial infarction who show severe fixed perfusion defects. In patients without myocardial infarction, gated SPET imaging allows differentiation between an attenuation artefact and a fixed perfusion defect due to coronary artery disease. In addition, gated SPET may show diminished ventricular function in normally perfused segments possibly due to myocardial stunning. The addition of gated SPET myocardial perfusion imaging increases diagnostic confidence and may have direct clinical implications for optimal patient management.     

The occurrence of false-positive technetium-99m sestamibi bull's eye defects in different reference databases

Myocardial perfusion single-photon emission tomographic (SPET) imaging has been shown to be sensitive in the detection of coronary artery disease (CAD), whereas its specificity has been suboptimal. The aim of the present study was to study the frequency of abnormal bull's eye perfusion defects in a large age-stratified group of healthy subjects undergoing myocardial SPET assessed by comparison with two existing commercially available reference databases. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a less than 5% likelihood of CAD underwent rest and exercise technetium-99m sestamibi SPET. The false-positive response rate, defined as a significant reversible defect, was 12% when compared to the CEqual database and 29% when compared to the Cedars-Sinai database. With the CEqual program, rest defects occurred in 12% of the subjects. Defects occurred more often in women than in men, but the difference did not attain statistical significance. Significant defects were most frequent in the inferior wall and in women in the anterior wall as well. The distribution of defects was independent of age. Our results suggest that the specificity of^99mTc-sestamibi myocardial SPET using commercially available reference files is suboptimal. The risk of obtaining a falsepositive test result in subjects undergoing^99mTc-sestamibi myocardial SPET with a very low likelihood of CAD was higher than anticipated. With both reference files false-positive test results were most frequently observed in the inferior wall. Our data suggest that commercial reference files for myocardial SPET need to be optimised, and should be used with caution. The use of attenuation correction may prove to be a major step forward.