Intra-patient reproducibility of myocardial SPECT imaging with 201Tl

Background  To define the physical and clinical reproducibility of ²⁰¹Tl myocardial perfusion SPECT (MPS), this study assesses the variation between two repeated rest ²⁰¹Tl MPS with repositioning only, with a two-hour time interval and with phantom measurements as a reference. Methods  Three anthropomorphic thorax phantoms were filled with ²⁰¹Tl. For each phantom five repeated ²⁰¹Tl MPS were obtained. In addition, in 20 patients repeated ²⁰¹Tl rest-MPS and in 26 patients early and delayed ²⁰¹Tl rest-MPS were performed. Quantitative analysis was done using MunichHeart. Statistical methods were used to calculate variability. Visual analysis was performed by 2 independent observers. Results  The average variation between repeated phantom MPS was 0.5% (95% confidence interval (CI): −0.4% to 1.4%). For patient scans this was −5.0% (95% CI: −2.5% to −7.5%) and between early and delayed ²⁰¹Tl MPS −15.5% (95% CI: −11.7% to −19.3%). Visual assessment revealed no clinical significant differences between rest ²⁰¹Tl and repeated or delayed ²⁰¹Tl MPS. Conclusions  Repositioning in phantom ²⁰¹Tl MPS does not cause significant variation. Repeated ²⁰¹Tl MPS in patients shows 5.0% decrease of ²⁰¹Tl in 30 minutes, which increases to 15% during a two-hour time interval without quantitative or visual regional differences. This decrease indicates a time-related washout of ²⁰¹Tl, but does not change clinical diagnosis.     

Prospective multicenter evaluation of rapid, gated SPECT myocardial perfusion upright imaging

Background  A novel three-dimensional (3D) iterative image reconstruction method (3D-OSEM) has been developed that in phantom studies yielded comparable image quality at one half the imaging time. In this study, we compared standard (STD) and rapid (nSPEED) protocols for diagnostic quality of images and quantitation of end-diastolic volume (EDV), end-systolic volume (ESV), left ventricular ejection fraction (LVEF), and perfusion defect severity. Methods  At 11 US community centers, 448 patients prospectively underwent rest–stress-gated SPECT imaging using Tc-99m-labeled agent. The difference in quality and diagnostic equivalence of STD and nSPEED images were blindly evaluated by three experts. Defect intensity was quantitated as %normal in the three coronary artery territories. Results  Studies were abnormal in 40% of patients. In 98.7% of stress and 98% of rest images, the nSPEED image quality was identical to or better than the STD images. nSPEED images were diagnostically equivalent to the STD in 444/448 (99%) patients. A high correlation was observed between nSPEED and STD studies for measurement of EDV (Y = 0.957X, R ² = 0.99), ESV (Y = 0.962X, R ² = 0.99), and LVEF (Y = 1.005X, R ² = 0.96). STD and nSPEED studies were not significantly different (P = ns) for quantitative perfusion defect severity. Conclusion  Rapid, gated rest–stress myocardial perfusion upright SPECT imaging may be achieved without compromising perfusion and function information. Financial support for this study was partly provided by Digirad Corporation, Poway, CA.     

Quantification of regional myocardial wall thickening on electrocardiogram-gated SPECT imaging

BACKGROUND: Current assessment of regional left ventricular function with electrocardiogram (ECG)-gated single photon emission computed tomography (SPECT) imaging is generally performed by visual inspection. The objective of this study was to develop and validate a new computer algorithm for quantifying regional left ventricular wall thickening on ECG-gated SPECT images. METHODS: Regional wall thickening was measured from count density changes during the cardiac cycle observed in 24-sector circumferential count distribution profiles generated from each of 8 frames of an ECG-gated SPECT study. Wall thickening was expressed as the percent count increase during systole relative to end diastole. The program was tested in a phantom simulation and in patient studies consisting of a pilot study (n = 40) and a validation study (n = 33). In the phantom study varying degrees of wall thickening were simulated. The pilot study included 20 normal subjects with low likelihood (<3%) of coronary disease and 20 patients with prior myocardial infarction. Mean wall thickening - 2 standard deviations, measured in normal subjects, defined the lower limit of normal wall thickening. This criterion was tested in the validation study in 13 normal subjects and 20 patients with prior myocardial infarction. Abnormal wall thickening was characterized by extent (percent of circumferential profile) and severity (minimal thickening). RESULTS: The phantom study showed excellent linear correlation between wall thickening computed by the new software and actual wall thickening (r = 0.98). Interobserver and intraobserver reproducibility of quantitative assessment of minimal wall thickening were excellent (r = 0.98 and 0.99, P < .001). Regional wall thickening varied considerably from apex to base in the same ventricle among normal subjects. The average lower limit of normal wall thickening was 25% to 30% at the apex, 19% to 24% in the mid-ventricle, and 13% to 20% at the base of the left ventricle. In the validation study 11 of 13 normal subjects had wall thickening profiles within the pre-defined normal range. All 20 patients with prior myocardial infarction had abnormal regional wall thickening. Minimal regional wall thickening in the infarct areas was 5.4% +/- 5.5%, compared with 30.1% +/- 9.1% wall thickening in comparable anatomic areas in normal subjects (P < .001). CONCLUSION: Regional wall thickening can be quantified reliably from regional count density changes during the cardiac cycle on ECG-gated SPECT images. The new software measured the extent and severity of abnormal regional wall thickening relative to normal files. The method is highly reproducible. Clinical validation showed good differentiation between normal subjects and patients with prior infarction. Quantification of regional wall thickening may enhance diagnostic accuracy and reproducibility of interpretation of gated SPECT imaging.     

Optimisation of protocol for low dose CT-derived attenuation correction in myocardial perfusion SPECT imaging

PURPOSE: In clinical routine, attenuation correction (AC) using X-ray CT is a relatively new method for reducing attenuation artefacts. We evaluated the quality of attenuation maps generated with very low tube current to minimise exposure due to transmission scanning. METHODS: SPECT/CT acquisitions were performed with a Millenium VG3 gamma camera with the Hawkeye CT device (GE Medical Systems). In phantom studies, determination of linear absorption coefficients (mu) for air, water and Teflon was carried out. The attenuation maps in both stress and resting studies from 62 patients (21 females and 41 males, age 63.7 +/- 11.0 years, BMI 30.0 +/- 5.7 kg/m(2)) were compared. All patients underwent exercise or pharmacologic stress testing and a resting study for comparison using Tc-99m MIBI or Tc-99m Tetrofosmin. AC in stress studies was performed using 2.5 mA tube current (set as default), whereas 1.0 mA was used in resting studies. RESULTS: In both phantom and patient studies, differences of linear absorption coefficients were not significant (p > 0.05). Effective dose decreased from 0.90 mSv down to 0.36 mSv, respectively. CONCLUSION: Our results indicate that reliable attenuation maps (mu-maps) of the thorax can be obtained even with the use of very low tube current. In our study, radiation exposure in CT-based AC for myocardial perfusion SPECT was substantially lowered (60% reduction). This is of particular importance in high-risk patients who may have to undergo follow-up scans and in research studies on volunteers. The procedure introduced is relatively simple and can be transferred to other SPECT/CT devices, which allow adjustment of tube current.     

Quantification of SPECT myocardial perfusion images: Methodology and validation of the Yale-CQ method

BACKGROUND: Quantification of single photon emission computed tomography (SPECT) images is important for reproducible and accurate image interpretation. In addition, SPECT quantification provides important prognostic information. The purpose of this study was to validate the Yale circumferential quantification (Yale-CQ) method in phantom studies. METHODS: Myocardial perfusion defects of varying extent and severities were simulated in a cardiac phantom with fillable defect inserts. Forty-five different phantom configurations simulated 45 different myocardial perfusion defect sizes, ranging from 1.6% to 32% of the cardiac phantom volume. Automatic processing was compared with manual processing in the phantom SPECT studies. RESULTS: The automatic Yale-CQ algorithm performed well in all phantom studies. Compared with manual processing, the mean absolute error for automatically determined center of short axis slices was 0.27 pixel in the x direction, 0.45 pixel in the y direction, and 0.15 pixel in radius. Quantification of phantom defects with the Yale-CQ method correlated well with actual defect sizes (R = 0.99), but there was a systematic underestimation (mean error = -7.9%). With derived correction factors the overall correlation between 45 phantom defects and actual defect sizes was excellent, and the estimation error was significantly improved (R = 0.98, mean error = -0.82% for manual method and -0.95% for automatic method). CONCLUSION: The automatic processing algorithm performs well for the phantom studies. Myocardial perfusion abnormalities can be quantified accurately by use of the Yale-CQ method. Quantified SPECT defect size can be expressed as a percentage of the left ventricle.     

SPECT myocardial perfusion imaging with prone-only acquisitions: correlation with coronary angiography

Background  Recent evidence suggests that combining supine and prone acquisitions during stress-gated SPECT myocardial perfusion imaging (MPS) improves detection of obstructive coronary artery disease (CAD), though the additional imaging time required may not be feasible in routine clinical practice. MPS with prone-only acquisitions is occasionally performed in many laboratories, though little is known about the ability of modern MPS with prone-only acquisitions to detect obstructive CAD. Our goal was to assess the ability of MPS with prone-only acquisitions to detect obstructive CAD as determined by coronary angiography. Methods and Results  We studied 386 patients referred for MPS with either recent coronary angiography or a low pretest likelihood of coronary artery disease. All rest and stress images were obtained exclusively in the prone position. The sensitivity of prone-only MPS was 88% for detecting ≥50% coronary artery stenosis and 92% for detecting ≥70% coronary artery stenosis as determined by coronary angiography. Normalcy rate for prone-only MPS in patients with low probability for CAD was 95%, and normalcy rates did not significantly differ among coronary artery distributions. Conclusions  The findings of this study suggest that MPS using prone-only acquisitions is a reasonable diagnostic option for the detection of ischemia due to obstructive coronary artery disease.     

门控断层显像在心肌灌注断层显像中的应用

使用门控心肌断层显像不但减低了心脏搏动产生的图像边缘模糊,提高了对心肌缺血诊断的灵敏度和特异性,而且通过傅立叶变换和图像边缘识别技术等图像处理技术,可以在一次采集的信息基础上同时获得心脏的心肌血流灌注、心肌活力、室壁运动、射血功能和收缩协调性等参数,提高了核素心脏检查的价值,为临床准确判断患者的心脏状况,选择治疗方案,预后及疗效评价提供了更可靠的数据。本文就其近年来的临床应用进行综述。     

衰减校正技术在SPECT心肌灌注显像中的应用分析

心肌灌注显像（MPI）的伪影对其图像质量以及图像的判别产生较大影响,造成假阳性率较高。目前针对软组织衰减所造成的伪影主要有以下2类校正技术,非X射线校正法（如变换体位采集、门控采集和固体153Gd线源穿透式采集）和CT衰减校正法。明确2种方法的应用范围及其优缺点,使临床医师在阅片中对伪影有正确的分析判断,从而提高诊断的准确率。     

Simplified normal limits and automated quantitative assessment for attenuation-corrected myocardial perfusion SPECT

Background  We aimed to compare normal limits and the detection of coronary artery disease (CAD) with attenuation-corrected (AC) and non-attenuation-corrected (NC) myocardial perfusion single photon emission computed tomography (MPS) by use of a recently improved automated quantification technique. Methods and Results  We acquired 415 rest/stress technetium 99m MPS studies on a Vertex dual-detector camera with a gadolinium 153 line source (Vantage Pro). Gender-specific NC, AC, and gender-combined AC normal limits were created from rest/stress images of 50 women and 50 men with a low likelihood of CAD (<5%) and a median body mass index (BMI) of 30 kg/m2 in each gender group. BMI-specific normal limits (<30 kg/m2 and >30 kg/m2) were also compared. Total perfusion deficit and 17-segment summed scores in 174 patients were compared with angiography, and normalcy rates were established from 141 studies of low-likelihood patients. There were no differences between low-BMI and high-BMI normal limits for AC or NC studies. Male and female normal limits differed in 12 of 17 segments for NC stress studies and in 3 of 17 segments for AC stress studies (P < .01). The sensitivity, specificity, and normalcy rates for stenoses with 70% narrowing or greater were 89%, 73%, and 91%, respectively, for NC studies and 87%, 80%, and 95%, respectively, for AC studies (P = not significant). Conclusion  Automated detection of CAD by AC and NC MPS demonstrated similar sensitivity, specificity, and normalcy rates. Some gender differences were noted for AC normal limits.     

Quantitative myocardial-perfusion SPECT: Comparison of three state-of-the-art software packages

Background  We almed to compare the automation and diagnostic performance in the detection of coronary artery disease (CAD) of the 4DMSPECT (4DM), Emory Cardiac Toolbox (EMO), and QPS systems for automated quantification of myocardial perfusion. Methods and Results  We studied 328 patients referred for rest/stress Tc-99m sestamibi imaging, 140 low-likelihood patients and 188 with angiography. Contours were corrected when necessary. All other processing was fully automated. A 17-segment analysis was performed, and a summed stress score (SSS) ≥4 was considered abnormal. The average SSSs (±SD) for 4DM, EMO, and QPS were 10.5±9.4, 11.1±8.3, and 10.1±8.9 respectively (P=.02 for QPS versus EMO). The receiver operator characteristics areas-under-the-curve for the detection of CAD (±SEM) were 0.84±0.03, 0.76±0.04, and 0.88±0.03 for 4DM, EMO, and QPS, respectively (P=.001 for QPS versus EMO, and P=.03 for 4DM versus EMO), Normalcy rate was higher for QPS and 4DM versus EMO, at 91% and 94% versus 77%, respectively (P=.02). Sensitivity was higher for QPS (87%) versus 4DM (80%) (P=.045). Specificity was higher for QPS (71%) versus EMO (49%) (P=.01). The accuracy rate was higher for QPS versus 4DM and EMO, at 83% versus 77% and 76%, respectively, (P=.05). Conclusions  There are differences in myocardial-perfusion quantification, diagnostic performance, and degree of automation of software packages. AW. is a Fellow of the Save A Heart Foundation. Inc., at Cedars-Sinai Medical Center.     

Comparative localization of myocardial ischemia by exercise electrocardiography and myocardial perfusion SPECT

BACKGROUND: Prior angiographic study has shown that the patterns of ST-segment depression during exercise do not provide localizing information of the responsible coronary lesion. However, little is known regarding the ability of exercise-induced ST-segment displacement to localize myocardial perfusion defects. METHODS AND RESULTS: We studied 552 consecutive patients without prior myocardial infarction who had reversible perfusion defect in one vascular territory on rest 201Tl/exercise 99mTc-labeled sestamibi dual-isotope myocardial perfusion single photon emission computed tomography (SPECT) and ischemic ST depression or elevation during exercise. Of these, 192 patients had angiographically documented coronary artery disease (CAD). Two hundred thirty-two patients had maximal ST depression in anterior leads, 247 patients had maximal ST depression in inferior leads, and 45 patients had similar maximal ST depression in both anterior and inferior leads. Twenty-eight (5%) patients had ST elevation with absent Q waves. In patients with maximal ST depression in anterior leads, perfusion defects were found in the territory of the left anterior descending coronary artery (LAD) in 30%, in the territory of the right coronary artery (RCA) in 52%, and in the territory of the left circumflex coronary artery (LCX) in 18%. In patients with maximal ST depression in inferior leads, perfusion defects were found in RCA territory in 44%, in the LAD territory in 42%, and in the LCX territory in 14%. Compared with exercise ST depression, the less common finding of ST elevation did provide accurate localization of perfusion defects. When ST elevation was greatest in the anterior leads, 96% of patients had LAD territory defects. When ST elevation was most prominent in the inferior leads, 100% patients had RCA territory defects. Data of coronary angiograms demonstrated that myocardial perfusion SPECT correctly identified the most stenotic coronary disease for LAD (94%), LCX (72%), and RCA (75%). CONCLUSIONS: The findings of this study indicate that the site of maximal ST-segment depression does not identify the localization of myocardial perfusion defects. However, the less common finding of exercise-induced ST-segment elevation does predict localization of myocardial ischemia.     

IQ·SPECT、碲锌镉探测器SPECT和传统SPECT在心肌灌注显像中的应用分析

IQ·SPECT与碲锌镉（CZT）探测器SPECT是心肌灌注显像新技术,与传统SPECT相比,具有灵敏度和空间分辨率高、采集时间短、注射显像剂剂量少及辐射剂量低等优点。与传统SPECT不同（低能高分辨率平行孔准直器）,IQ·SPECT使用SMART-ROOM准直器及心脏为焦点的采集模式,提高了灵敏度;CZT探测器SPECT的探测器为半导体,取代了传统NaI晶体探测器,提高了能量分辨率、空间分辨率、灵敏度及信噪比等,并可定量分析心肌血流储备。笔者主要对三者的成像原理、性能参数及临床应用进行综述。     

Myocardial perfusion SPECT imaging in patients with myocardial bridging

BACKGROUND: Although myocardial perfusion single photon emission computed tomography (SPECT) imaging is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, only a few patients with myocardial bridging have been evaluated with nuclear techniques. Furthermore, it has been suggested that dipyridamole stress images might underestimate perfusion defects compared with exercise stress images. This study was done to determine the concordance of exercise stress SPECT images with that obtained by dipyridamole stress SPECT images as a means of detecting ischemia in patients with myocardial bridging. METHODS AND RESULTS: Sixteen consecutive patients with angina and normal arteries but myocardial bridging of the left anterior descending artery underwent rest-exercise stress SPECT imaging. Within 2 weeks after angiograms were obtained, only dipyridamole stress images were repeated. The mean angiographic systolic occlusion within the myocardial bridges was 73% +/- 10%. Overall, the prevalence of an abnormal scan was no different in patients who underwent exercise stress myocardial perfusion imaging (MPI) as compared with patients who underwent dipyridamole stress MPI (14/16 [88%] vs 13/16 [81%], respectively; P = .953). Exercise stress MPI showed a higher stress score than dipyridamole stress MPI, but the difference did not reach statistical significance (7.5 +/- 3.3 vs 6 +/- 2.7, P = .147). The strength of agreement among exercise stress MPI and dipyridamole stress MPI studies was good (kappa = 0.765; 95% CI, 0.318 to 1.211; P < .05). CONCLUSIONS: Cardiac SPECT studies can be used effectively for assessing ischemia in patients with angina and myocardial bridging. The evaluation of myocardial perfusion with dipyridamole stress SPECT imaging showed a good agreement with exercise stress SPECT imaging for the detection of ischemia in this group of patients.     

SPECT myocardial perfusion versus fractional flow reserve for evaluation of functional ischemia: A meta analysis

Purpose

The present meta-analysis illustrates the accuracy of myocardial perfusion SPECT (MPS) to diagnose functional stenotic coronary artery disease (CAD) with fractional flow reserve (FFR) as standard reference.

Methods

All investigators screened and selected studies that compared MPS with FFR in symptomatic patients with suspected CAD. Patients and study characteristics were independently extracted by two investigators; differences were resolved by consensus.

Results

13 articles, including 1,017 patients, 699 vessels were included in the study. No significant publication bias was detected (P = 0.65). At the patient level, the summary sensitivity and specificity were 77% (95% confidence interval [CI], 70–83%) and 77% (95%CI, 67–84%) for MPS. Vessel-level pooled sensitivity was 66% (95%CI, 57–74%) and specificity was 81% (95%CI, 70–89%). The overall diagnostic performance of MPS was moderate. [The area under the summary receiver operating characteristic (sROC) curve was 0.83]. No study influenced the pooled results larger than 0.03.

Conclusions

The accuracy between FFR and MPS SPECT was moderate.     

Temporal resolution of multiharmonic phase analysis of ECG-gated myocardial perfusion SPECT studies

Background. Multiharmonic phase analysis (MHPA) was developed to assess left-ventricular dyssynchrony from gated myocardial perfusion single-photon emission computed tomography (GSPECT) studies. This study was intended to determine the temporal resolution of MHPA. Methods. A reference normal GSPECT study with 128 frames/cycle was simulated using NCAT, a nonuniform rational B-splines-based cardiac torso phantom. It was shifted in the time domain to insert phase delays. Realistic GSPECT studies (8 or 16 frames/cycle) were then obtained by down-sampling the reference and shifted studies. All GSPECT projections were generated with attenuation, scatter, collimator blurring, and Poisson noise. Seventeen regional phases were calculated from the GSPECT reconstructions (filtered back-projection without compensation for physical factors), using linear interpolation for the reference study, and MHPA for the realistic studies. Comparing the regional phases between the realistic studies without and with shifts determined whether MHPA could identify certain phase delays. Results. When there were enough counts/pixel (>10 counts/pixel), MHPA with either 1, 2, or 3 harmonics could resolve a phase difference of 5.6°, corresponding to 1/64 of the cardiac cycle. Conclusions. With clinically equivalent counts, the temporal resolution of MHPA is 1/64 of a cardiac cycle. Achieving this high temporal resolution from data with low temporal resolution demonstrates the benefit of replacing discrete points with continuous harmonic functions. The authors receive royalties from sales of the Emory Cardiac Toolbox. The terms of this arrangement were reviewed and approved by Emory University in accordance with its conflict-of-interest practice. This study was supported in part by an ASNC/GE Healthcare Research Award from the American Society of Nuclear Cardiology Foundation. This study was also part of an NIH research (1R01HL 094438-01).     

SPECT心肌灌注显像在糖尿病无症状性心肌缺血中的临床价值

冠心病是糖尿病患者常见的并发症,其中,无症状性心肌缺血由于起病隐匿而不被重视,容易发生严重的心血管事件。SPECT心肌灌注显像作为常用的无创性检查方法,在心肌缺血的筛查中发挥着越来越重要的作用。该文对SPECT心肌灌注显像在糖尿病患者无症状性心肌缺血的筛查、诊断及预后判断中的应用进行了综述。     

Assessment of perfusion, function, and myocardial metabolism after infarction with a combination of low-dose dobutamine tetrofosmin gated SPECT perfusion scintigraphy and BMIPP SPECT imaging

BACKGROUND: Tetrofosmin gated single photon emission computed tomography (SPECT) allows simultaneous assessment of regional myocardial perfusion, global and regional left ventricular function, and function at rest and during pharmacologic intervention. SPECT with fatty acid analogues, such as beta-methyl-iodophenyl-pentadecanoic acid (BMIPP), can be used to monitor metabolic changes induced by myocardial ischemia. In this work, the results of both studies obtained in patients with recent myocardial infarction are integrated. METHODS: Twenty patients underwent tetrofosmin and BMIPP scintigraphy with a 3-head camera. Two consecutive tetrofosmin gated SPECT acquisitions were performed 60 minutes after administration of technetium-99m tetrofosmin (925 MBq) at rest (3x20 stops of 9 s; matrix 64x64 over 360 degrees . One acquisition was made at rest, and the second was made during dobutamine infusion (10 microg/kg/min). Regional functional abnormalities were quantified and expressed as wall thickening severity (WTsev) in arbitrary units. Left ventricular ejection fraction and volumes were assessed with the Cedars Sinai algorithm. BMIPP imaging started 20 minutes after iodine 123-BMIPP (150 MBq) administration at rest (3x32 stops of 60 s; matrix 64x64 over 360 degrees; medium energy collimators). Tracer uptake was scored according to a 25-segment model. RESULTS: Sixteen of 18 patients had regional functional abnormalities at baseline (average WTsev 13.7 units). The WTsev score at baseline correlated well with the degree of residual perfusion. During dobutamine infusion, WTsev did not change (from 23.4 to 23.6 units) in 5 patients; it decreased (from 16.1 to 5.9 units) in 11 patients; and it increased (from 13.0 to 22.3 units) in 3 patients. An increase or decrease in WTsev during dobutamine infusion was associated with the presence of a considerable amount of BMIPP mismatched myocardium, whereas no change in WTsev was preferentially associated with a BMIPP matched pattern and perfusion defects with a higher severity score. CONCLUSION: Immediately after infarction, the severity of regional dysfunction at rest correlated well with the perfusion defect severity. Improvement in regional function during dobutamine administration is associated with less severe perfusion defects and a considerable amount of BMIPP mismatched myocardium, both suggesting viability.     

门控SPECT心肌灌注显像评估急性心肌梗死患者心肌挽救量的研究进展

急性心肌梗死（AMI）患者经皮冠状动脉介入治疗（PCI）的目的在于尽可能地挽救濒死心肌。心肌挽救量（MS）与患者能否获益密切相关,在PCI的疗效评估及预后判断中具有重要价值。评价MS需明确初始心肌危险区面积（AAR）和心肌最终梗死面积（FIS）,二者之差即为MS。通过急诊时和PCI后2次99Tcm-甲氧基异丁基异腈门控SPECT心肌灌注显像（GSMPI）可分别定量AAR和FIS,从而获得MS,结果客观、准确,其临床价值在早期的大样本研究中已得到肯定。但在急诊时行GSMPI受到很多限制,致使AAR较难获得。近年来有学者提出的新显像方案,仅通过PCI后早期行1次GSMPI即可测定AAR,替代了2次显像法计算得到MS,其可行性及在临床中的实用价值显著提高。同时,新显像方案也扩展了核素GSMPI在AMI诊疗中的应用范围,为AMI患者的危险度分层提供了补充信息。笔者拟对GSMPI评估AMI患者MS的新显像方案的机制、应用价值、优势及发展前景作一综述。     

Different manifestations of coronary artery disease by stress SPECT myocardial perfusion imaging,coronary calcium scoring,and multislice CT coronary angiography in asymptomatic patients with type 2 diabetes mellitus

Background. We sought to assess prospectively the evidence for silent coronary artery disease (CAD) in asymptomatic patients with type 2 diabetes mellitus by stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging, coronary artery calcium (CAC) scoring, and multislice computed tomographic (MSCT) coronary angiography. Methods. One hundred asymptomatic patients (aged 30 to 72 years) with type 2 diabetes mellitus and one or more risk factors for CAD were prospectively recruited from an outpatient diabetes clinic. All patients underwent adenosine technetium-99m sestamibi SPECT imaging, CAC scoring, and 64-slice MSCT coronary angiography. Results. Twenty-three patients (23%) had abnormal stress SPECT imaging, consistent with inducible myocardial ischemia, whereas 60 patients (60%) had positive CAC scoring (18 patients [18%] with significant CAC >401), and 70 patients (70%) had abnormal MSCT coronary angiography (24 patients [24%] with significant, ≥50% stenosis). Of 77 patients with normal SPECT, 44 had a positive CAC score (10 patients [13%] >401), and 54 showed CAD on MSCT angiography (16 patients [21%] with ≥50% stenosis). Of 23 patients with an abnormal SPECT, 16 patients had a positive CAC score (8 patients [35%] >401), and 16 patients had CAD on MSCT angiography (8 patients [35%] with ≥50% stenosis). Overall, 17 patients (17%) had more than 2 significantly abnormal diagnostic test results, and 5 patients had three tests with significantly abnormal results. Conclusions. In this cohort of asymptomatic patients with type 2 diabetes mellitus, different modalities visualized different aspects of silent coronary atherosclerosis. Anatomic evidence of coronary atherosclerosis (CAC and MSCT) occurred more frequently than functional evidence (stress SPECT). However, clinically significant manifestations of CAD were observed in about one-quarter to one-fifth of patients by each modality, either separately or combined. The relative prognostic value of each modality needs to be determined by a follow-up of this cohort. This work was supported by an unrestricted grant from BMS Medical Imaging. In addition, J.J.B. has received research grants from GE Healthcare.     

The effect of beta-blockers on the diagnostic accuracy of vasodilator pharmacologic SPECT myocardial perfusion imaging

Background  The effect of beta (β) blockers on the accuracy, particularly the sensitivity, of vasodilator radionuclide myocardial perfusion imaging (MPI) is not entirely clear. This study aimed to further assess the effect of β-blockers on the ability of MPI to identify significant and high-risk coronary artery disease (CAD). Methods and Results  For 555 patients who underwent vasodilator MPI and had coronary angiography within 90 days, global and per-vessel sensitivities and specificities were calculated, and were found to be similar between patients taking β-blockers and those who were not. β-blockers did not decrease the ability to detect patients with multivessel disease. Summed stress scores and summed rest scores were likewise similar in both groups. To account in part for catheterization referral bias and the potential of false-negative MPI studies in patients receiving β-blockers, survival analysis was performed on 2646 patients with normal MPI studies who did not undergo cardiac catheterization and failed to demonstrate significant mortality difference related to the taking of β-blockers. Conclusions  β-blocker therapy does not diminish the ability of vasodilator stress MPI to detect clinically significant CAD, nor hide the mortality risk of patients with normal studies not referred for catheterization. Presented in part at the American Society of Nuclear Cardiology 9th Scientific Session, September 2004, New York, NY.