Evaluation by Contrast-Enhanced Electron Beam Computed Tomography of Myocardial Perfusion and Tissue Characteristics in Congenital Aortic Stenosis

145

ontrast enhanced multislice spiral computed tomography (CE-MSCT) has been proposed as a means of evaluating coronary artery stenoses. [1][2][3] In just a few years, technological advances have progressively improved the temporal resolution. Recent studies showed that CE-MSCT allows for a noninvasive assessment of coronary artery disease (CAD) in a clinical setting. [4][5][6][7][8][9][10] In addition to coronary artery assessment, CE-MSCT can also provide information about myocardial perfusion. Koyama et al reported that CE-MSCT could describe acute myocardial infarction (AMI) as a perfusion defect after the injection of a bolus of contrast medium. 11 Their data showed myocardial viability and function after AMI.No attempt to detect myocardial ischemia using pharmacological stress MSCT has been reported previously. Adenosine triphosphate (ATP) is widely used as a coronary vasodilator to detect myocardial ischemia in the fields of magnetic resonance imaging, 12 nuclear imaging 13 and echocardiography. 14 We hypothesized that CE-MSCT can describe myocardial ischemia as a hypo-perfusion area (HPA) using the ATP provocation test. The present study was designed to: (i) to test our hypothesis; and (ii) to evaluate the potential of the ATP stress CE-MSCT in a clinical setting. Methods Study ProtocolThe study protocol necessitated that the enrolled patients underwent both ATP-provocation/non-provocation CE-MSCT and stress thallium-201 myocardial perfusion scintigraphy (MPS), and received conventional coronary angiography (CAG) as required. All patients gave their informed consent and the protocol was approved by the hospital's ethics committee.The entry criteria were as follows: (i) de novo effort or rest stable angina (documented ST-T change on electrcardiogram (ECG), or relieved by administration of nitroglycerin); (ii) no history of coronary angiography; and (iii) asymptomatic patients with a high probability of CAD (ie, multiple coronary risk factors) or abnormal findings in exercise ECG.The exclusion criteria included: (i) acute myocardial infarction (within 3 months); (ii) unstable angina (recent onset of angina within a month, severe and worsening clinical symptom); (iii) chronic atrial fibrillation; (iv) deteriorated renal function (serum creatinine >1.5 mg/dl); (v) pregnancy, hyperthyroidism or a known allergic reaction to Background The present study was designed to: (i) detect myocardial ischemia in contrast enhanced multislice spiral computed tomography (CE-MSCT) using adenosine triphosphate (ATP) pharmacological stress test; and (ii) evaluate the potential of ATP stress CE-MSCT in a clinical setting. Methods and ResultsTwelve patients underwent ATP stress CE-MSCT and stress thallium-201 myocardial perfusion scintigraphy (MPS) and 9 of the patients received conventional coronary angiography (CAG). Dual CE-MSCT scans were performed for stress and rest images, with and without intravenous infusion of ATP (0.16 mg·kg -1 ·min -1 ) at intervals of 20 min. Myocardial perfusion and coronary artery were visually eval...

Section: Discussionsupporting

confidence: 85%

Myocardial Perfusion Imaging Using Adenosine Triphosphate Stress Multi-Slice Spiral Computed Tomography Alternative to Stress Myocardial Perfusion Scintigraphy

Kurata

Mochizuki

Koyama

et al. 2005

145

“…26 Because of its superior spatial resolution, MDCT is an alternative tool for evaluating the transmural myocardial perfusion of congenital heart disease and reperfused AMI. 27,28 Our most recent study suggests that MDCT can assess transmural perfusion and predict the long-term contractile recovery after AMI. 8 Based on those data, we used first-pass MDCT as the golden standard for evaluating transmural myocardial perfusion in order to compare the data of MCE.…”

Section: Advantage Of Magnetic Resonance Imaging (Mri) and Mdctmentioning

confidence: 99%

Evaluation of Transmural Myocardial Perfusion by Ultra-Harmonic Myocardial Contrast Echocardiography in Reperfused Acute Myocardial Infarction

Wada¹,

Yasu²,

Kotsuka³

et al. 2005

pproximately 20-35% of angiographically successful recanalizations of the infarct-related artery in patients with acute myocardial infarction (AMI) fail to salvage ischemic myocardium because of a discrepancy between an open epicardial coronary artery and no blood flow in the damaged distal microvessels. [1][2][3][4] Regions with no-reflow show no improvement in regional function over time despite recanalization of the epicardial coronary vessels. These patients also have poorer global left ventricular (LV) systolic function, malignant ventricular arrhythmias, intractable congestive heart failure, progressive LV remodeling, cardiac rupture, and higher mortality. 2,3,5,6 Bogaert et al reported that functional recovery of viable subepicardial tissue is a mechanism of late improvement in the regional and global LV fraction after a so-called transmural myocardial infarction (MI). 7 Furthermore, our recent Circulation Journal Vol.69, September 2005 study in patients with AMI showed that assessing the microcirculation in the transmural myocardial layers by multidetector computed tomography (MDCT) predicted progressive LV remodeling and the long-term recovery in contraction. 8 Myocardial contrast echocardiography (MCE) has been proposed as a powerful modality for assessing transmural myocardial perfusion, on the basis of bedside safely, economy and repeated performance compared with other imaging modalities, because of its superior resolution in time and space without exposure to radiation. [9][10][11][12][13][14] The aims of the present study were to assess transmural myocardial perfusion by MCE and compare the results with those of MDCT and to determine whether MCE can predict the long-term recovery of LV function in patients with AMI. Methods Patient PopulationTwenty patients who had experienced their first anterior AMI during the period 2001 to 2002, had total occlusion (TIMI 0) of the proximal left anterior descending artery (LAD) and who had undergone successful balloon reperfusion therapy (TIMI 3) within 24 h of onset were investigated. The average age was 66±13 years, the male:female ratio was 17:3, the average maximum creatine kinase was 2,509±2,003 IU/ml. None showed collateral flow to the Background The transmural distribution of myocardial perfusion is important for predicting the contractile reverse of an infarcted wall in reperfused acute myocardial infarction (AMI). Evaluating transmural myocardial perfusion by myocardial contrast echocardiography (MCE) could predict the long-term recovery of left ventricular (LV) function. Methods and ResultsThe study group comprised 20 consecutive patients with a first-episode anterior AMI with total occlusion of the proximal left anterior descending artery, who underwent successful percutaneous coronary intervention within 24 h of onset. MCE was performed on the 15th day after the onset, using ultraharmonic gray-scale imaging with intermittent end-systolic triggering every 4 beats or every 6 beats. Regions of interest were placed over both the endocardial and epica...

“…An evaluation of myocardial blood flow (MBF) is also important for studying the pathophysiology of the disease process. A few studies have reported the utility of cardiac MDCT to qualitatively assess myocardial perfusion using a late-enhancement protocol and the adenosine triphosphate (ATP) load technique, [15][16][17][18][19] but quantitative evaluation studies have not been carried out.Therefore, in this study, we investigated the feasibility of cardiac MDCT technology for quantitative assessment of MBF using the ATP-load technique. …”

mentioning

confidence: 99%

Quantification of Regional Myocardial Blood Flow Using First-Pass Multidetector-Row Computed Tomography and Adenosine Triphosphate in Coronary Artery Disease

Kido

Kurata

Hara

et al. 2008

lectrocardiography (ECG)-gated multidetector-rowcomputed tomography (MDCT) has developed remarkably in the past several years, with improvements in spatial and temporal resolution. [1][2][3] Several studies have focused on its usefulness for assessing the coronary artery lumen, and others studies have demonstrated its capability to evaluate coronary plaques, so the technique has gained acceptance as a valuable tool for coronary imaging in the clinical setting. [4][5][6][7][8][9][10][11] Because of the retrospective acquisition, the same data acquired for coronary computed tomography (CT) imaging can also be reconstructed over a cardiac cycle, allowing dynamic cardiac imaging; and we recently reported that wall motion and systolic thickening could be accurately estimated as functional parameters. 12-14 ECG-gated MDCT technology can therefore evaluate cardiac blood flow from virtually any perspective, including important angles for the interventional approach and for myocardial perfusion.Of these potential applications of cardiac MDCT, myocardial perfusion has so far been less investigated, but its assessment is important for the diagnosis of ischemia and infarction, and for the therapeutic strategy and follow-up. An evaluation of myocardial blood flow (MBF) is also important for studying the pathophysiology of the disease process. A few studies have reported the utility of cardiac MDCT to qualitatively assess myocardial perfusion using a late-enhancement protocol and the adenosine triphosphate (ATP) load technique, [15][16][17][18][19] but quantitative evaluation studies have not been carried out.Therefore, in this study, we investigated the feasibility of cardiac MDCT technology for quantitative assessment of MBF using the ATP-load technique. Methods PatientsFrom April 2006 to May 2007, taking the exclusion criteria into account, 14 patients (11 men, 3 women, age range 52-79 years, mean 69.2 years) underwent ATP-provocation contrast enhanced MDCT, stress thallium-201 myocardial perfusion scintigraphy (MPS), and conventional coronary angiography (CAG). The entry criteria were: (i) de novo effort or rest angina (documented ST-T change on ECG, or relieved by administration of nitroglycerin); (ii) no history of CAG; and (iii) asymptomatic patients with a high probability of coronary artery disease (CAD) (ie, multiple coronary risk factors) or abnormal findings on stress ECG and single-photon emission computed tomography (SPECT). The ATP-load cardiac CT and CAG had an average 40-day interval, and the ATP-load cardiac CT and MPS inspection had an average interval of 29.2 days. Patient characteristics are shown in Table 1. No patient had a history of previous myocardial infarction (MI) and there were no significant differences between men and women in age, clinical symptoms and coronary risk factors.Circ J 2008; 72: 1086 -1091 (Received November 21, 2007; revised manuscript received February 5, 2008; accepted February 7, 2008