Pairash Saiviroonporn

Comparison of cardiovascular magnetic resonance of late gadolinium enhancement and diastolic wall thickness to predict recovery of left ventricular function after coronary artery bypass surgery

BackgroundThe objective was to compare the value of late gadolinium enhancement (LGE) and end-diastolic wall thickness (EDWT) assessed by cardiovascular magnetic resonance (CMR) in predicting recovery of left ventricular function after coronary artery bypass surgery (CABG).MethodsWe enrolled patients with coronary artery disease and left ventricular ejection fraction < 45% who were scheduled for CABG. Regional contractility was assessed by cine CMR at baseline and 4 months after CABG. EDWT and LGE were assessed at baseline. Predictors for improvement of regional contractility were analyzed.ResultsWe studied 46 men and 4 women with an average age of 61 years. Baseline left ventricular ejection fraction was 37 ± 13%. A total of 2,020 myocardial segments were analyzed. Abnormal wall motion and the LGE area were detected in 1,446 segments (71.6%) and 1,196 segments (59.2%) respectively. Wall motion improvement was demonstrated in 481 of 1,227 segments (39.2%) that initially had wall motion abnormalities at baseline. Logistic regression analysis showed that the LGE area, EDWT and resting wall motion grade predicted wall motion improvement. Comparison of Receiver-Operator-Characteristic (ROC) curves demonstrated that the LGE area was the most important predictor (p < 0.001). Adding information from LGE to the EDWT can decrease the number of false predictions by EDWT alone from 483 to 127 segments.ConclusionLGE and EDWT are independent predictors for functional recovery after revascularization. However, LGE appears to be a more important factor and independent of EDWT.

Prevalence and prognosis of myocardial scar in patients with known or suspected coronary artery disease and normal wall motion

BackgroundSome patients may have normal wall motion after myocardial infarction. The aim of this study was to determine the prevalence and prognosis of patients with myocardial scar in the absence of abnormal wall motion. We studied patients with suspected or known coronary artery disease (CAD) who were referred for cardiovascular magnetic resonance (CMR) for the assessment of global and regional cardiac function and late gadolinium enhancement (LGE) and had normal left ventricular wall motion. Prognostic value was determined by the occurrence of hard endpoints (cardiac death and nonfatal myocardial infarction) and major adverse cardiac events (MACE) which also included hospitalization due to unstable angina or heart failure or life threatening ventricular arrhythmia.ResultsA total 1148 patients (70.3%) were studied. LGE was detected in 104 patients (9.1%). Prevalence of LGE increased in patients with increased left ventricular mass. Average follow-up time was 955 ± 542 days. LGE was the strongest predictor for hard endpoints and MACE.ConclusionLGE was detected in 9.1% of patients with suspected or known CAD and normal wall motion. LGE was the strongest predictor of significant cardiac events.

Comparison of the region-based and pixel-wise methods for cardiac T2* analysis in 50 transfusion-dependent Thai thalassemia patients.

Purpose: To compare the observer variability of the conventional region-based (RB) to the typical and proposed pixel-wise (PW) methods for cardiac T2* analysis in thalassemia patients. Design and Methods: Fifty thalassemia major patients were enrolled for the study. Short-axis bright- and black-blood sequences were acquired and analyzed using the RB and PW methods. Regions were defined using the whole septum (WS) or partial septum (PS). From the same PS region, results were reported by mean (PS-PW) and median (MPS-PW). Intraobserver and interobserver variabilities were investigated on all data set by 2 independent observers blinded to the result. Results: The T2* values from the PS-PW and MPS-PW methods were comparable to the conventional WS-RB method on both scanning techniques. When comparing the interobserver variability from the WS-RB to the PS-PW method, the coefficient of variation of the PS-PW method was equivalent (4.5% vs 4.7%, P = NS) for the bright-blood technique but 31% lower (4.0% vs 2.8%, P = 0.21) for the black-blood technique. The proposed MPS-PW method performed even better with respect to the conventional WS-RB method, decreasing interobserver coefficient of variation by 24% (4.5% vs 3.5%, P = 0.08) and 42% (4.0% vs 2.4%, P = 0.02), respectively. Intraobserver reproducibility followed the same trend. Conclusions: The proposed PW method using the median of T2* values calculated from partial interventricular septum region provided lower intraobserver and interobserver variabilities compared with the conventional RB or typical PW methods.

Magnetic resonance imaging abnormalities in right ventricular outflow tract tachycardia and the prediction of radiofrequency ablation outcome.

Background: Recent reports have shown abnormalities on cardiac magnetic resonance imaging (MRI) in patients with right ventricular outflow tract (RVOT) tachycardia.

Prognostic significance of left ventricular mass by magnetic resonance imaging study in patients with known or suspected coronary artery disease.

Objectives To study the prognostic value of left ventricular mass (LVM) assessed by cardiac magnetic resonance in patients with known or suspected coronary artery disease. Methods We studied patients who were referred for cardiac magnetic resonance for the assessment of cardiac function, LVM, and late gadolinium enhancement (LGE). Prognostic value was determined by the occurrence of hard cardiac endpoint, including death or nonfatal myocardial infarction and major adverse cardiac event, which also included hospitalization due to heart failure or unstable angina and life-threatening ventricular arrhythmia. We analyzed prognostic value of LVM index stratified by quintiles and specific percentile ranges. Results A total of 2194 patients with the average age of 65 ± 11 years were enrolled. Average left ventricular ejection fraction and LVM index were 59.2 ± 19.4% and 56.6 ± 21.3 g/m2, respectively. LGE was present in 785 patients (35.8%). Average follow-up duration was 926 ± 582 days. Hard events and major adverse cardiac events occurred in 92 (4.2%) and 210 patients (9.6%). Cox regression analysis showed that left ventricular ejection fraction, LGE, and LVM index were independent predictors for clinical events. The highest quartile of LVM index had the greatest risk for clinical events independent of other factors, including left ventricular ejection fraction and LGE. Conclusion LVM index by cardiac magnetic resonance is an independent predictor for cardiovascular event in patients with known or suspected coronary artery disease.

Interactive 3-dimensional segmentation of MRI data in personal computer environment.

We describe a method of interactive three-dimensional segmentation and visualization for anatomical magnetic resonance imaging (MRI) data in a personal computer environment. The visual feedback necessary during 3-D segmentation was provided by a ray casting algorithm, which was designed to allow users to interactively decide the visualization quality depending on the task-requirement. Structures such as gray matter, white matter, and facial skin from T1-weighted high-resolution MRI data were segmented and later visualized with surface rendering. Personal computers with central processing unit (CPU) speeds of 266, 400, and 700 MHz, were used for the implementation. The 3-D visualization upon each execution of the segmentation operation was achieved in the order of 2 s with a 700 MHz CPU. Our results suggest that 3-D volume segmentation with semi real-time visual feedback could be effectively implemented in a PC environment without the need for dedicated graphics processing hardware.

Intersite validations of the pixel-wise method for liver R2* analysis in transfusion-dependent thalassemia patients: a more accessible and affordable diagnostic technology

BACKGROUND AND OBJECTIVES MRI-R2* has been accepted as a clinical tool for monitoring iron overload in thalassemia patients, especially for monitoring liver iron concentration (LIC). The most optimal and practical method of analysis however, is still open to further investigations. Our objective was to investigate intra- and intersite observer variability of the pixel-wise method for liver R2* analysis in thalassemia patients using a mono-exponential with a constant offset model. PATIENTS AND METHODS We performed 88 liver R2* measurements on 72 thalassemia major patients. A single breath-hold multi-echo gradient-echo sequence was acquired and analyzed at both the reference (REF) and local (LOC) sites. The analysis defined the region of interest in the whole liver parenchyma, excluding the great vessels, and were reported as median values. RESULTS The R2* values from the REF and LOC were statistically comparable for all comparisons. The intrasite and intersite observer variation were 0.75% (less than 0.9%) and 2.5%, respectively, both of which are comparable to previous reports, but substantially lower than conventional region-based approaches. CONCLUSION The low variation of the R2* also yielded excellent variation in the tabulated hepatic iron content. However, caution is required when comparing the results to different implementation methods and appropriate evaluation and validation of methodology for any new scan site is essential before its clinical use.

Comparison of Diagnostic and Prognostic Value of Different Electrocardiographic Criteria to Delayed-Enhancement Magnetic Resonance Imaging for Healed Myocardial Infarction

The accuracy of various electrocardiographic (ECG) criteria for the diagnosis of healed myocardial infarction (MI) has never been validated. The objective of this study was to determine the accuracy and prognostic value of standard ECG criteria for the diagnosis of healed MI compared with cardiac magnetic resonance (CMR). Consecutive patients with known or suspected coronary artery disease who were referred for CMR were studied. Twelve-lead electrocardiography and CMR were performed the same day. A standard CMR protocol including a delayed-enhancement (DE) technique was performed. The prognostic value of using various ECG criteria and DE-CMR was assessed for the occurrence of cardiac death, nonfatal MI, or major adverse cardiac events. We studied 1,366 patients. Average follow-up was 31.4 +/- 15.8 months. Myocardial scar was detected in 507 patients (37.1%) using DE-CMR. Healed MI using various ECG criteria had sensitivity, specificity, and accuracy of 44% to 59%, 91% to 95%, and 75% to 79% compared with DE-CMR, respectively. Multivariable Cox regression analysis showed that myocardial scar using DE-CMR was the most powerful predictor for cardiac events, followed by left ventricular ejection fraction. In the absence of DE-CMR data, MI using European Society of Cardiology/American College of Cardiology (ESC/ACC) 2000 criteria was the most powerful predictor. In conclusion, various ECG criteria had limited sensitivity, but high specificity, for the diagnosis of healed MI compared with myocardial scar using DE-CMR. Myocardial scar, left ventricular ejection fraction, and MI using ESC/ACC 2000 criteria were important predictors for cardiac events.

Stimulated echo diffusion weighted imaging of the liver at 3 Tesla

Diffusion time (Δ) effect in diffusion measurements has been validated as a sensitive biomarker in liver fibrosis by rat models. To extend this finding to clinical study, a reliable imaging technique is highly desirable. This study aimed to develop an optimal stimulated echo acquisition mode (STEAM) diffusion‐weighted imaging (DWI) method dedicated to human liver imaging on 3 Tesla (T) and preliminarily investigate the dependence effect in healthy volunteers.

Detection of cardiac iron overload with native magnetic resonance T1 and T2 mapping in patients with thalassemia

BACKGROUND To investigate the diagnostic performance of native cardiac magnetic resonance (CMR) T1 and T2 mapping for cardiac iron overload (CIO) in thalassemia patients. METHODS All thalassemia patients who underwent CMR were enrolled on a clinical 1.5T scanner. Native T1 mapping with the Modified Look-Locker Inversion recovery (MOLLI) technique, T2 mapping using a black-blood multi-echo spin-echo technique, and conventional T2* mapping using multi-echo gradient-echo techniques were performed. CIO was defined by a T2* of <20ms; while severe CIO was considered as <10ms. RESULTS A total of 200 patients were enrolled in the study (23.9±14.6years old [mean±SD], 102 male). Among these, 8 patients (4.0%) had CIO. Both native T1 and T2 times were significant different among patients with no CIO, mild-to-moderate CIO, and severe CIO (1012.7±57.7 vs. 846.4±34.4 vs 601.3±34.6ms for T1, p<0.05; 59.6±6.5 vs. 48.7±2.5 vs. 32.8±1.2ms for T2, p<0.05). The best cut-off values for detection of CIO were 887 and 52ms for T1 and T2, respectively. This yielded a sensitivity, specificity and area under the curve (AUC) of 100%, 98.4% and 0.997 respectively for T1, in comparison to 100%, 88.8% and 0.961 respectively for T2. CONCLUSIONS Native T1 mapping can differentiate between severe, mild-to-moderate, and no CIO, which appears to be a promising technique for detection and assessment of myocardial iron.