Quantitative analysis of myocardial ischaemia on end-diastolic thallium 201 perfusion images

ECG gating of images with thallium 201 (²⁰¹T1) may improve the representation of myocardial perfusion by allowing isolation of the end-diastolic (ED) portion of the cardiac cycle. To characterize this phenomenon, circumferential distribution profiles for ED and conventional total-cycle images (TC) with²⁰¹T1 were analysed after summing ECG gated acquisitions; redistribution was defined as net washing of²⁰¹T1 for specific myocardial segments visualized on the left anterior oblique images. Scintigraphic data were compared with the presence of coronary stenoses in 150 patients. ED images had relatively less activity in the inferoseptal and inferoapical region than TC profiles. The ED mode of washout analysis provided more frequent confirmation of visually suggested redistribution than did the TC mode (84% incidence of net wash in for ED, 69% for TC). ED analysis showed a higher incidence of net²⁰¹T1 wash in in relation to critical circumflex and left anterior descending artery lesions, but yielded a similar overall performance to TC analysis in distinguishing patients with diseased coronary arteries from normal subjects. Thus, in selected cases, analysis of ED images could assist in confirming 2°1T1 redistribution.     

Quantitative analysis of transmural gradients in myocardial perfusion magnetic resonance images

Conventional quantitative assessments of myocardial perfusion analyze the temporal relation between the arterial input function and the myocardial signal intensity curves, thereby neglecting the important spatial relation between the myocardial signal intensity curves. The new method presented in this article enables characterization of sub‐endocardial to sub‐epicardial gradients in myocardial perfusion based on a two dimensional, “gradientogram” representation, which displays the evolution of the transmural gradient in myocardial contrast uptake over time in all circumferential positions of the acquired images. Moreover, based on segmentation in these gradientograms, several new measurements that characterize transmural myocardial perfusion distribution over time are defined. In application to clinical image data, the new two‐dimensional representations, as well as the newly defined measurements revealed a clear distinction between normal perfusion and inducible ischaemia. Thus, the new measurements may serve as diagnostic markers for the detection and characterization of epicardial coronary and microvascular disease. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.     

Quantitative analysis of planar technetium-99m-sestamibi myocardial perfusion images using modified background subtraction

Standard interpolative background subtraction, as used for thallium-201 (201Tl), may create artifacts when applied to planar technetium-99m-Sestamibi (99mTc-Sestamibi) images, apparently because of the oversubtraction of relatively high extra-cardiac activity. A modified background subtraction algorithm was developed and compared to standard background subtraction in 16 patients who had both exercise-delayed 201Tl and exercise-rest 99mTc-Sestamibi imaging. Furthermore, a new normal data base was generated. Normal 99mTc-Sestamibi distribution was slightly different compared to 201Tl. Using standard background subtraction, mean defect reversibility was significantly underestimated by 99mTc-Sestamibi compared to 201Tl (2.8 +/- 4.9 versus -1.8 +/- 8.4, p less than 0.05). Using the modified background subtraction, mean defect reversibility on 201Tl and 99mTc-Sestamibi images was comparable (2.8 +/- 4.9 versus 1.7 +/- 5.2, p = NS). We conclude, that for quantification of 99mTc-Sestamibi images a new normal data base, as well as a modification of the interpolative background subtraction method should be employed to obtain quantitative results comparable to those with 201Tl.     

冠状动脉支架植入前后及术后半年~(99)Tc~m-MIBI心肌断层显像定量分析

目的　通过对冠状动脉 (简称冠脉 )支架植入前后进行99Tcm 甲氧基异丁基异腈 (MIBI)心肌断层显像 ,以了解心肌灌注缺损程度、范围 ,判断SPECT在术前筛选、术后疗效评价、后期随访中的价值。方法　对 5 1例冠心病患者冠脉支架植入前后和 2 1例植入后半年 ,分别做静态和潘生丁负荷SPECT检查 ,定量分析心肌灌注缺损的部位、程度及范围。结果　术前 5 0例中 ,心肌血流灌注程度 >80 % (灌注缺损程度 <2 0 % )、灌注缺损范围 <2 0 % (比值越大 ,灌注缺损面积越大 )者为 0例 ;术后 1周有 7例灌注缺损程度、8例灌注缺损面积已完全正常 (14%和 16 % ) ;术前严重灌注缺损 <49%的 34例 (6 8% ) ,术后 1周 16例 (32 % )有改善 ;术前严重灌注缺损面积 >70 %的 35例 ,术后 1周 10例有改善 ,急性心肌梗死改善更明显。术前和术后 1周静态SPECT心肌灌注程度 38 0 5 %和 5 7 40 % ,改善 19 35 % ,术前和术后 1周静态SPECT心肌灌注缺损面积为 70 75 %和 5 5 91% ,改善 14 74% ,在术后 1周及半年心肌灌注缺损程度、灌注缺损面积均有明显改善 (P <0 0 0 1)。而术前、术后 1周及术后半年潘生丁负荷SPECT心肌灌注缺损程度、灌注缺损面积与术前、术后 1周及术后半年静息SPECT心肌灌注缺损程度、灌注缺损面积差异无显著性 (<3%     

"Circumferential profiles:" a new method for computer analysis of thallium-201 myocardial perfusion images

A method for computer analysis of thallium-201 scintigrams is described, in which the left-ventricular activity is measured along radii constructed from the center of the left ventricle (LV) to each point on the LV circumference. Data are then displayed graphically as a "circumferential profile" of normalized activity against radial location. Thallium defects are identified and scored by comparison of the profile curve with empirically determined normal limits. In patients with coronary artery disease, defect scores were found to be quantitative and reproducible, and to agree generally with subjective visual analysis.     

A stochastic interpretation of thallium myocardial perfusion scintigraphy

A method is presented for the quantitative interpretation of thallium-201 myocardial perfusion studies. The data are planar images collected immediately following the stress injection, and 4 to 6 hours later. Data analysis consists of preprocessing, including thresholding of the original data, and data reduction using a variant of the circumferential profile methods. The profiles are subdivided into segments, and for each segment the difference between the norm and the actual data is computed. This difference is a quantitative symptom, whose size is assumed to be related to the probability of having the disease. The relationship between the size of the symptom in each of nine segments (three segments/view in three views) and the probability of disease is expressed in a table in which for 30 diseases (combinations of vascular lesions) the sensitivity for each of the nine symptoms is described as a Gaussian function whose average and standard deviation are computed from previous validated cases. Using an arbitrary prevalence, the post-testing probability can then be computed using Bayes' formula sequentially. The sensitivities, however, are not expressed as a binary function of the presence or absence of a symptom, but as a distribution function defined by experience. The method is sensitive for the detection of isolated left anterior descending disease (100%) and triple vessel disease (96%). When specific combinations of vascular lesions are recognized the specificity increases from 79% (when unspecified abnormalities are recognized) to 87% when left anterior descending disease or triple vessel disease is recognized.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative myocardial perfusion SPECT

In recent years, there has been much interest in the clinical application of attenuation compensation to myocardial perfusion single photon emission computed tomography (SPECT) with the promise that accurate quantitative images can be obtained to improve clinical diagnoses. The different attenuation compensation methods that are available create confusion and some misconceptions. Also, attenuation-compensated images reveal other image-degrading effects including collimator-detector blurring and scatter that are not apparent in uncompensated images. This article presents basic concepts of the major factors that degrade the quality and quantitative accuracy of myocardial perfusion SPECT images, and includes a discussion of the various image reconstruction and compensation methods and misconceptions and pitfalls in implementation. The differences between the various compensation methods and their performance are demonstrated. Particular emphasis is directed to an approach that promises to provide quantititve myocardial perfusion SPECT images by accurately compensating for the 3-dimensional (3-D) attenuation, collimator-detector response, and scatter effects. With advances in the computer hardware and optimized implementation techniques, quantitatively accurate and highquality myocardial perfusion SPECT images can be obtained in clinically acceptable processing time. Examples from simulation, phantom, and patient studies are used to demonstrate the various aspects of the investigation. We conclude that quantitative myocardial perfusion SPECT, which holds great promise to improve clinical diagnosis, is an achievable goal in the near future. Supported in part by the US Public Health Service grant No CA39463 of the Cancer Institute. The contents of this work are solely the responsibility of the authors     

Quantitative assessment of myocardial perfusion abnormality on SPECT myocardial perfusion imaging is more reproducible than expert visual analysis

Background  Current guidelines of Food and Drug Administration for the evaluation of SPECT myocardial perfusion imaging (MPI) in clinical trials recommend independent visual interpretation by multiple experts. Few studies have addressed whether quantitative SPECT MPI assessment would be more reproducible for this application. Methods and Results  We studied 31 patients (age 68 ± 13, 25 male) with abnormal stress MPI who underwent repeat exercise (n = 11) or adenosine (n = 20) MPI within 9-22 months (mean 14.9 ± 3.8 months) and had no interval revascularization or myocardial infarction and no change in symptoms, stress type, rest or stress ECG, or clinical response to stress on the second study. Visual interpretation per FDA Guidance used 17-segment, 5-point scoring by two independent expert readers with overread of discordance by a third expert, and percent myocardium abnormal was derived from normalized summed scores. The quantitative magnitude of perfusion abnormality was assessed by the total perfusion deficit (TPD), expressing stress, rest, and ischemic perfusion abnormality. High linear correlations were observed between visual and quantitative size of stress, rest, and ischemic defects (R = 0.94, 0.92, 0.84). Correlations of two tests were higher by quantitative than by visual methods for stress (R = 0.97 vs R = 0.91, P = 0.03) and rest defects (R = 0.94 vs R = 0.82, P = 0.03), respectively, and statistically similar for ischemic defects (R = 0.84 vs R = 0.70, P = ns). Conclusions  In stable patients having serial SPECT MPI, quantification is more reproducible than visual for magnitude of perfusion abnormality, suggesting its superiority for use in randomized clinical trials and monitoring the effects of therapy in an individual patient. See related editorial, doi: This study was presented in part at the Society of Nuclear Medicine 55th Annual Meeting, New Orleans, Louisiana, June 14-18, 2008.     

Experience with 201thallium in detection of myocardial infarction

Our preliminary experimental and clinical results with ²⁰¹Tl myocardial scanning are presented. 48 patients with normal coronary vessels, acute transmural myocardial infarction, localized and diffuse coronary heart diseases and congestive myocardiopathy were investigated. Results of scans and the usual cardiological investigations were in good agreement thus justifying further use of ²⁰¹Tl myocardial scintigraphy as an adjunctive method in cardiology.Presented at the Radionuclide Meeting, Lund/Schweden, June 6./7. 1975.     

Quantitative assessment of thallium-201 images

Conclusion Since quantitative assessment of²⁰¹Tl images is mainly used as an aid or a complement to visual evaluation, its usefulness may be in assessing questionable findings and in reducing observer bias rather than in establishing new diagnostic criteria. However, it is apparent that results reported from computer-assisted evaluation of left ventricular²⁰¹Tl images show higher sensitivity and specificity than findings from simple visual analysis [4, 5, 9, 18]. This cumulates in a 96% sensitivity in detecting coronary heart disease [10]. Moreover, such easily derived values as left ventricular count rate have proved to be informative parameters [7, 13, 15, 26]. The difficulties involved in the use of maximal left ventricular²⁰¹Tl uptake values as a reference seem to be decreased by using one²⁰¹Tl injection for both rest and exercise imaging (“redistribution analysis”) [17], since the diagnosis is not made from absolute but from relative changes within a related distribution image. The problems that remain to be solved for reliable and reproducible employment of quantifying methods are: (1) determination of the correct border of the left ventricular wall (imaged in tangent) with respect to both the left ventricular cavity (imaged posterior to the en-face-viewed myocardium) and to paracardiac activity, and (2) determination of the correct background values to be subtracted. Some of these problems may be resolved by more advanced imaging techniques as, for example, computerized emission tomography.     

冠状动脉支架植入前后及术后半年99Tcm-MIBI心肌断层显像定量分析

目的 通过对冠状动脉（简称冠脉）支架植入前后进行99Tcm-甲氧基异丁基异腈（MIBI）心肌断层显像,以了解心肌灌注缺损程度,范围,判断,SPECT在术前筛选,术后疗效评价,后期随访中的价值。方法,对51例冠心病患者冠脉支架植入前后和21例植入后半年,分别做静态和潘生丁负荷SPECT检查,定量分析心肌灌注缺损的部位,程度及范围。结果 术前50例中,心肌血流灌注程度＞80％（灌注缺损程度＜20％）,灌注缺损范围＜20％（比值越大,灌注缺损面积越大）者为0例,术后1周有7例灌注缺损程度,8例灌注缺损面积已完全正常（14％和16％）,术前严重灌注缺损＜49％的34例（68％）,术后1周16例（32％）有改善,术前严重灌注缺损面积＞70％的35例,术后1周10例有改善,19．35％,术前和术后1周静态SPECT心肌灌注缺损面积为70．75％和55．91％,改善14．74％,在术后1周及半年心肌灌注缺损程度,灌注缺损面积均有明显改善（P＜0．001）,而术前,术后1周及术后半年潘生丁负荷SPECT心肌灌注缺损程度,灌注缺损面积与术前,术后1周及术后半年静息SPECT肌灌注缺损程度,灌注缺损面积差异无显著性（＜3％,P＞0．05）,结论 定量分析术后1周和半年SPECT心肌灌注缺损程度,灌注缺损面积较大前有明显改善,SPECT对冠心病诊断,介入治疗前病例筛选,术后疗效评价及后期随访有临床应用价值。     

Automated quantitative coronary computed tomography correlates of myocardial ischaemia on gated myocardial perfusion SPECT

Purpose

Automated software tools have permitted more comprehensive, robust and reproducible quantification of coronary stenosis, plaque burden and plaque location of coronary computed tomography angiography (CTA) data. The association between these quantitative CTA (QCT) parameters and the presence of myocardial ischaemia has not been explored. The aim of the present investigation was to evaluate the association between QCT parameters of coronary artery lesions and the presence of myocardial ischaemia on gated myocardial perfusion single-photon emission CT (SPECT).

Methods

Included in the study were 40 patients (mean age 58.2?±?10.9 years, 27 men) with known or suspected coronary artery disease (CAD) who had undergone multidetector row CTA and gated myocardial perfusion SPECT within 6 months. From the CTA datasets, vessel-based and lesion-based visual analyses were performed. Consecutively, lesion-based QCT was performed to assess plaque length, plaque burden, percentage lumen area stenosis and remodelling index. Subsequently, the presence of myocardial ischaemia was assessed using the summed difference score (SDS ≥2) on gated myocardial perfusion SPECT.

Results

Myocardial ischaemia was seen in 25 patients (62.5 %) in 37 vascular territories. Quantitatively assessed significant stenosis and quantitatively assessed lesion length were independently associated with myocardial ischaemia (OR 7.72, 95 % CI 2.41–24.7, p?<?0.001, and OR 1.07, 95 % CI 1.00–1.45, p?=?0.032, respectively) after correcting for clinical variables and visually assessed significant stenosis. The addition of quantitatively assessed significant stenosis (χ ²?=?20.7) and lesion length (χ ²?=?26.0) to the clinical variables and the visual assessment (χ ²?=?5.9) had incremental value in the association with myocardial ischaemia.

Conclusion

Coronary lesion length and quantitatively assessed significant stenosis were independently associated with myocardial ischaemia. Both quantitative parameters have incremental value over baseline variables and visually assessed significant stenosis. Potentially, QCT can refine assessment of CAD, which may be of potential use for identification of patients with myocardial ischaemia.