Hidenari Matsumoto

Peri-Infarct Zone on Early Contrast-Enhanced CMR Imaging in Patients With Acute Myocardial Infarction

OBJECTIVES The aims of this study were to evaluate hyperenhanced regions on contrast-enhanced cardiovascular magnetic resonance (CE-CMR) imaging in patients with acute myocardial infarction (AMI) between early contrast-enhanced cardiovascular magnetic resonance (ECE) (2 min) and late contrast-enhanced cardiovascular magnetic resonance (LCE) (10 to 15 min) after gadolinium administration, and to compare the CE-CMR images with area at risk (AAR) derived from T2-weighted (T2W) CMR. BACKGROUND Although CE-CMR imaging can demarcate the infarcted myocardium, the value of hyperenhancement in AMI is still in dispute. The size of hyperenhanced regions may vary with time, and overestimation can be often observed with early acquisition. METHODS Thirty-four patients with successfully reperfused AMI underwent CMR within 4 days after the event. Myocardial regions as percentage of left ventricular (LV) myocardium were quantified on CE and T2W images. Relative peri-infarct zone was calculated as the difference in hyperenhanced regions between ECE and LCE, normalized to the individual infarct size. RESULTS Both ECE and LCE images revealed hyperenhancement in the territory of the infarct-related artery in all patients. The hyperenhanced region on ECE extended transmurally and was consistently larger than that on LCE (39 ± 12% vs. 27 ± 12% of LV myocardium, p<0.001). The relative peri-infarct zone was inversely correlated with the transmurality of infarction (r=-0.59, p<0.001) and the time from symptom to reperfusion (r=-0.46, p<0.01). The hyperenhanced region on ECE was correlated with the T2W CMR-derived AAR (r=0.86, p<0.001) with the average difference of -0.8% and the limits of agreement of ±11.9%. CONCLUSIONS ECE depicts ischemically injured but salvaged myocardium, as well as infarcted myocardium in patients with AMI. The myocardium at risk and infarcted myocardium after reperfusion can be retrospectively assessed by the combination of ECE and LCE.

ECG-Edited Middiastolic Phase Reconstruction Improves Image Quality at 64-MDCT Coronary Angiography of Patients with Atrial Fibrillation

OBJECTIVE The aims of this study were to evaluate image quality at the absolute middiastolic and absolute end-systolic phases of 64-MDCT coronary angiography of patients with atrial fibrillation and to compare the findings with those among patients in sinus rhythm. SUBJECTS AND METHODS Nineteen consecutively registered patients with atrial fibrillation and 19 patients in sinus rhythm taking heart-rate-lowering agents as needed underwent MDCT. Images were reconstructed with a half-scan reconstruction algorithm after ECG editing (deletion of short R-R intervals, insertion of additional temporal windows into the middiastolic phase of long R-R intervals, and shift of R points). We used a 5-point scale (4, no motion artifacts; 0, unevaluable) to evaluate motion artifacts and coronary artery image discontinuities greater than 1 mm on the curved multiplanar reconstruction images. Each coronary artery image with a motion score of 2 or greater for all segments and with 2 or fewer discontinuities was considered acceptable for diagnosis. RESULTS Middiastolic images of patients with atrial fibrillation showed fewer motion artifacts and image discontinuities than did end-systolic images of patients with atrial fibrillation. Despite greater heart rate variability under the condition of similar mean heart rates in patients with atrial fibrillation, motion artifacts and image discontinuities on middiastolic images were not significantly different from those on sinus rhythm images. Acceptable quality was achieved on 91% of middiastolic atrial fibrillation images and 93% of sinus rhythm images. CONCLUSION ECG-edited middiastolic atrial fibrillation images with aggressive heart rate control were of better quality than end-systolic images in patients with atrial fibrillation. The diagnostic image quality of the middiastolic images was comparable with that of sinus rhythm images.

Temporal change of enhancement after gadolinium injection on contrast-enhanced CMR in reperfused acute myocardial infarction.

BACKGROUND A recent report demonstrated that early enhancement on contrast-enhanced cardiac magnetic resonance (CE-CMR) correlated with myocardial edema detected by T2-weighted CMR in reperfused acute myocardial infarction (AMI). However, the time at which the enhancement in salvaged myocardium disappears is yet to be determined. We aimed to examine the time course of the enhancement with the use of different quantification techniques and to compare the extent of enhancement with the myocardial edema. METHODS AND RESULTS CE-CMR was performed at 2-20 min after gadolinium administration in 32 AMI patients. The extent of enhancement (% myocardium) was quantified by manual delineation and the threshold methods of 2-5 SDs above remote myocardium. In subendocardial infarct, the enhancement was greatest at 2 min regardless of the quantification techniques and decreased with time, particularly in the first 6 min. In transmural infarct, the change in the size of enhancement was modest although the time course of enhancement varied according to the quantification techniques. The sizes of enhancement were not significantly different between 15 and 20 min regardless of the techniques and infarct transmurality. The best agreement with myocardial edema was found at 2 min with average differences of 0.5% and -1.2% and limits of agreement of ±20.2% and ±21.2% for the manual and 2-SD techniques, respectively. CONCLUSIONS The optimal timing for delineation of salvaged myocardium on CE-CMR is at 2min when the manual or 2-SD technique was employed. Imaging needs to be completed in a short time (ideally within a minute) because of rapid reduction of enhancement in salvaged myocardium.

Is Caffeine Abstention Necessary Before Adenosine-Induced Fractional Flow Reserve Measurement?

Caffeine antagonizes the pharmacological actions of adenosine by blocking adenosine receptor activity [(1)][1]. A protocol for adenosine stress myocardial perfusion imaging recommends that caffeine-containing products be withheld for 12 h before the test [(2)][2]. However, there has been no widely

Feasibility of free-breathing late gadolinium-enhanced cardiovascular MRI for assessment of myocardial infarction: Navigator-gated versus single-shot imaging

OBJECTIVES The aim of this study was to evaluate the feasibility of two free-breathing late gadolinium-enhanced cardiovascular magnetic resonance (LGE-CMR) techniques (two-dimensional segmented navigator-gated [NAV-LGE] and single-shot [SS-LGE]) by comparing with breath-hold LGE-CMR (BH-LGE) as reference. METHODS A total of 200 consecutive patients underwent the three LGE-CMR imaging techniques. BH patterns were assessed with dynamic navigator MR imaging. Image quality was graded on a 5-point scale (4=optimal; 0=not assessable). In patients with sufficient BH capability (diaphragmatic movement with a deviation of <3mm), hyperenhancement was scored with a 5-point scale, and global infarct size (%left ventricle) was quantified. RESULTS Compared to free-breathing LGE-CMR, BH-LGE had higher image quality grade in patients with sufficient BH capability (P<0.01 [vs. NAV-LGE]; P<0.001 [vs. SS-LGE]) but poorer image quality in patients with insufficient BH capability (P<0.001 [vs. NAV-LGE]; P<0.01 [vs. SS-LGE]). NAV-LGE had higher sensitivity for infarct detection than SS-LGE (97.1% vs. 88.4%, P<0.05), but specificity was not significantly different (97.3% vs. 94.7%, P=0.37). By Bland-Altman analysis, the average differences in global infarct size were 0.4% and 1.2%, and the limits of agreement were ± 4.0% and ± 5.9% for NAV- and SS-LGE, respectively. CONCLUSIONS Although both NAV- and SS-LGE improve the image quality in patients with insufficient BH capability, NAV-LGE is superior to SS-LGE in infarct detection and infarct size measurement. NAV-LGE can be a possible first-line technique for patients with inability to perform sufficient BH.

Late Gadolinium-Enhanced Cardiovascular MRI at End-Systole: Feasibility Study

OBJECTIVE The purpose of this article is to evaluate the image quality and infarct size of segmented late gadolinium-enhanced cardiovascular MRI at end-systole, compared with middiastole, in patients with sinus rhythm (SR) and to compare the image quality of end-systole images in patients with atrial fibrillation (AFib) to that of end-systole and middiastole images in patients with SR. SUBJECTS AND METHODS Study patients (n = 121) were distributed according to heart rate and rhythm: SR with low heart rate (≤ 65 beats/minute), SR with intermediate heart rate (66-75 beats/minute), SR with high heart rate (≥ 76 beats/minute), and AFib. Image quality was graded on a 5-point scale, where 4 equals optimal and 0 equals not assessable. Global infarct size (percentage of left ventricle [LV] myocardium) in patients with SR with myocardial infarction was quantified using a visual quantitative approach with a 5-point scale and a semiautomatic method. RESULTS End-systole imaging had higher image quality than did middiastole imaging for patients with SR with high heart rate, whereas middiastole imaging had higher image quality than did end-systole imaging for patients with SR with low heart rate (p < 0.05 for patients with SR with low heart rate, p = 0.60 for patients with SR with intermediate heart rate, and p = 0.001 for patients with SR with high heart rate). The quality of end-systole imaging in patients with AFib was not significantly different from that in patients with SR (p = 0.40 vs SR middiastole imaging and p = 0.38 vs SR end-systole imaging). The average difference of global infarct size was -0.3% and 0.2% of LV myocardium, and the limits of agreement were ± 2.4% and ± 3.3% of LV myocardium, for visual assessment and semiautomatic assessment, respectively. CONCLUSION End-systole imaging can provide accurate diagnosis of myocardial infarction, comparable to middiastole imaging. The image quality of end-systole imaging is less susceptible to heart rate and rhythm compared with middiastole imaging.

Effects of human atrial natriuretic peptide on myocardial performance and energetics in heart failure due to previous myocardial infarction.

BACKGROUND Human atrial natriuretic peptide (hANP) and spontaneous nitric oxide (NO) donor share cyclic guanosine monophosphate (cGMP) as a second messenger, but their effect on myocardium may differ. We compared the effect of hANP and sodium nitroprusside (SNP) on left ventricular (LV) mechano-energetics in heart failure (HF). METHODS Ten patients with HF due to previous myocardial infarction (LV ejection fraction: 45±3%) were instrumented with conductance and coronary sinus thermodilution catheters. LV contractility (Ees: slope of end-systolic pressure-volume relation) and the ratio of LV stroke work (SW) to myocardial oxygen consumption (SW/MVO2=mechanical efficiency) were measured in response to intravenous infusion of ANP (0.05 μg/kg/min) or SNP (0.3 μg/kg/min) to lower blood pressure by at least 10 mmHg, and changes in plasma cGMP. RESULTS SNP had no effect on Ees, SW, or MVO2, thus SW/MVO2 remained unchanged (40.54±5.84% to 36.59±5.72%, p=0.25). ANP increased Ees, and decreased MVO2 with preserved SW, resulting in improved SW/MVO2 (40.49±6.35% to 50.30±7.96%, p=0.0073). Infusion of ANP (10.42-34.95 pmol/ml, p=0.0003) increased cGMP levels, whereas infusion of SNP had no effect (10.42-12.23 pmol/ml, p=0.75). CONCLUSIONS Compared to SNP, the ANP-dependent increase in cGMP may ameliorate myocardial inotropy and energetics in HF.

Early enhancement on contrast-enhanced cardiovascular magnetic resonance imaging in takotsubo cardiomyopathy: Two cases

A 76-year-old woman presented to the hospital with acute chest pain. The ECG showed ST-segment elevation in the precordial leads and echocardiography revealed extensive midventricular and apical akinesis. The serum concentration of creatinine kinase MB was slightly elevated at 38 IU/L. Emergent cardiac catheterization confirmed the absence of obstructive coronary disease and typical takotsubo-like wall motion abnormalities. Cardiac magnetic resonance imaging (MRI) on day 2 showed wall motion abnormalities on cine imaging (Fig. 1a), myocardial edema on T2-weighted imaging (Fig. 1b), and hyperenhancement on contrast-enhanced (CE) imaging early (2 min) after gadolinium administration (Fig. 1c) in the midventricular and apical regions, in which the abnormal regions were approximately similar among different types of imaging. Hyperenhancement on early CE imaging significantly faded out with time after gadolinium administration (Fig. 1c). Another patient, a 61-year-old woman, was admitted to the hospital with acute onset of dyspnea. The ECG showed ST-segment elevation in leads I, AVL, and V2 through V6, and echocardiography revealed akinesis of the mid-anterior and apical walls. There was minimal elevation in creatinine kinase MB concentration (26 IU/L). Emergent cardiac catheterization ruled out the possibility of acute coronary syndrome and the case was diagnosed as takotsubo