Masaki Tachi

T2-Weighted Cardiac Magnetic Resonance Imaging of Edema in Myocardial Diseases

The purpose of this paper is to describe imaging techniques and findings of T2-weighted magnetic resonance imaging (MRI) of edema in myocardial diseases. T2-weighted cardiac MRI is acquired by combining acceleration techniques with motion and signal suppression techniques. The MRI findings should be interpreted based on coronary artery supply, intramural distribution, and comparison with delayed-enhancement MRI. In acute myocardial diseases, such as acute myocardial infarction and myocarditis, the edema is larger than myocardial scarring, whereas the edema can be smaller than the scarring in some types of nonischemic cardiomyopathy, including hypertrophic cardiomyopathy. T2-weighted MRI of edema identifies myocardial edema associated with ischemia, inflammation, vasculitis, or intervention in the myocardium and provides information complementary to delayed-enhancement MRI.

Delayed enhancement magnetic resonance imaging in hypertrophic cardiomyopathy with Basal septal hypertrophy and preserved ejection fraction: relationship with ventricular tachyarrhythmia.

Objective This study aimed to determine the relationship between delayed enhancement magnetic resonance imaging (DE MRI) and ventricular tachyarrhythmia in patients with hypertrophic cardiomyopathy (HCM) with basal septal hypertrophy and preserved ejection fraction (EF). Methods One hundred seven patients with HCM with basal septal hypertrophy and EF greater than 50% underwent cine and DE MRI. Myocardial scar was identified with DE MRI. We assessed whether patient,s background, cine MRI findings, presence of myocardial scar, or number of scarred myocardial segments was related to the occurrence of ventricular tachyarrhythmia. Results Patient,s age, family history of HCM, and number of scarred segments differed between the patients with and without the arrhythmia. A family history of HCM and number of scarred segments were significantly related to ventricular tachyarrhythmia (P < 0.01). Conclusions The number of scarred segments is the significant DE MRI parameter related to ventricular tachyarrhythmia in HCM with basal septal hypertrophy and preserved EF.

Relationship of postcontrast myocardial T1 value and delayed enhancement to reduced cardiac function and serious arrhythmia in dilated cardiomyopathy with left ventricular ejection fraction less than 35

Background Dilated cardiomyopathy (DCM) is often associated with progressive heart failure or ventricular arrhythmia. Look–Locker magnetic resonance imaging (MRI) allows quantitative evaluation of interstitial fibrosis by measuring the myocardial T1 value, and delayed enhancement (DE) MRI visualizes myocardial scar. Purpose To determine the relationship of postcontrast myocardial T1 value or DE to reduced cardiac function or sustained ventricular tachycardia (SVT) in DCM patients with a left ventricular ejection fraction (LVEF) <35%. Material and Methods We enrolled 41 patients with DCM. Correlations between the cardiac function parameters and postcontrast myocardial T1 value or extent of DE were evaluated. The relationship between SVT and the T1 values or extent of DE was assessed. The correlation between the extent of DE and the T1 value was also examined. Results The postcontrast myocardial T1 value was significantly correlated with the LVEF (P < 0.05; r = 0.31) and end-diastolic volume (P < 0.01; r = −0.40) in 40 patients with LVEF <35%. DE was not correlated with the cardiac function, but provided a high negative predictive value of 94.7% for SVT. No correlation was found between the myocardial T1 value and extent of DE. Conclusion In DCM patients with LVEF <35%, the postcontrast myocardial T1 value correlated with the severity of cardiac dysfunction, and the absence of DE indicated the low risk of SVT. Both MRI parameters should be estimated because they may reflect discrete forms of myocardial damages in patients with DCM.

Superiority of the extracellular volume fraction over the myocardial T1 value for the assessment of myocardial fibrosis in patients with non-ischemic cardiomyopathy

PURPOSE This study aimed to assess the efficacies of the myocardial T1 value and the extracellular volume fraction (ECV) for determining the severity of myocardial fibrosis in patients with non-ischemic cardiomyopathy. MATERIALS AND METHODS Myocardial fibrosis is considered the most important indicator of cardiac damage associated with non-ischemic cardiomyopathy. Recently, modified Look-Locker inversion recovery imaging (MOLLI) has been used for T1 mapping and measurement of the ECV for the assessment of myocardial fibrosis. The present study included 22 patients (mean age, 61.5±12.7; 21 male) with non-ischemic heart failure. Motion corrected myocardial T1 mapping was automatically performed using a MOLLI sequence, and the ECV was estimated from the pre- and post-contrast blood and myocardial T1 values corrected for the hematocrit level. All endomyocardial biopsy specimens were obtained from the inferoposterior left ventricular wall. The percentage of myocardial fibrosis (%F) was determined after Elastica Masson-Goldner staining as follows: (fibrosis area/[fibrosis area+myocardial area])×100. RESULTS No correlation was noted between the %F and the pre- (r=0.290, p=0.191) or post-contrast T1 values (r=-0.190, p=0.398); however, a significant correlation was noted between the %F and ECV (r=0.750, p<0.001). CONCLUSIONS In this study, the ECV reflected the extent of myocardial fibrosis, but the pre- and post-contrast T1 values did not. The ECV may be used to estimate the severity of myocardial fibrosis in patients with non-ischemic cardiomyopathy.

Myocardial fibrosis evaluated by look–locker and late gadolinium enhancement magnetic resonance imaging in apical hypertrophic cardiomyopathy: Association with ventricular tachyarrhythmia and risk factors

To evaluate the distribution and extent of myocardial fibrosis identified by either contrast‐enhanced Look–Locker or late gadolinium enhancement magnetic resonance imaging (LGE MRI) and their relationships between ventricular tachyarrhythmia or risk factors in apical hypertrophic cardiomyopathy (APH).

Myocardial T2 Mapping in Patients With Hypertrophic Cardiomyopathy.

Objective The aim of this study was to evaluate the usefulness of T2 mapping for detecting myocardial injuries in patients with hypertrophic cardiomyopathy (HCM). Methods Twenty-one HCM patients and 7 healthy volunteers were examined. The T2 values were measured at hyperintense areas (high-T2 areas) identified with T2 mapping, at late gadolinium enhancement (LGE) areas, and in nullified myocardium of the HCM patients. The associations between T2 values and laboratory data or LGE areas were assessed. Results High-T2 areas had significantly greater T2 values than LGE areas (P < 0.05) and nullified areas (P < 0.01) of HCM and normal myocardium (P < 0.01). The presence of high-T2 areas was associated with an increase in troponin T levels (P = 0.02), and T2 values correlated with the levels of brain natriuretic peptide (P = 0.036, r = 0.86). Conclusions T2 mapping identified myocardial injuries suggested by the laboratory data in HCM.

Magnetic resonance imaging of microvascular obstruction in hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation

Background The clinical significance of microvascular obstruction (MO) in hypertrophic cardiomyopathy (HOCM) after percutaneous transluminal septal myocardial ablation (PTSMA) remains unknown. Purpose To assess the relationship between the location of MO and the improvement in symptoms and pressure gradient after PTSMA in patients with HOCM. Material and Methods Twenty-three patients with HOCM underwent MRI within 24 weeks after PTSMA. The MO was defined visually as the hypointense region adjacent to the left or right ventricular cavity, which was surrounded by myocardial infarction. The location of MO and improvement in clinical symptoms and pressure gradient at 3–6 months follow-up were assessed. Results MO was observed in 16 patients who underwent MRI within 7 weeks after PTSMA. Left-sided MO was observed in 12 patients, and right-sided MO was observed in four patients. Improvement in clinical symptoms and reduction in the pressure gradient were not sufficient in the patients with right-sided MO, while PTSMA was effective in the patients with the left-sided MO. Conclusion The location of MO identified by MRI may be related to the effectiveness of PTSMA at the short-term follow-up. The left-sided MO is related to complete improvement in clinical symptoms and pressure gradients.

Evaluation of nonscarred myocardial T1 value using contrast-enhanced look-locker cardiac MRI and its relationship to cardiac function in dilated cardiomyopathy: Comparison of 1.5 and 3.0 Tesla MRI.

To assess relationship between nonscarred myocardial T1 value measured using contrast‐enhanced Look‐Locker MRI and cardiac function in dilated cardiomyopathy (DCM) at 1.5 Tesla (T) and 3.0T MRI.

Three-dimensional Look-Locker MRI for evaluation of postcontrast myocardial and blood T1 values: Comparison with two-dimensional Look-Locker and late gadolinium enhancement MRI

Background Two-dimensional (2D) Look-Locker MRI technique can identify myocardial fibrosis, but cannot cover the whole left ventricle during a single scan. Purpose To develop breath-hold three-dimensional (3D) Look-Locker MRI for the evaluation of postcontrast myocardial and blood T1 values and myocardial scarring in the left ventricle. Material and Methods A phantom and 24 patients with myocardial diseases underwent gadolinium-enhanced 2D and 3D Look-Locker MRI using a 1.5-T unit. We compared the T1 value of the phantom and the values of the myocardium and blood in the patients between the two Look-Locker MRI sequences. In the patient study, the scan ordering of the two Look-Locker MRI was selected randomly. We also assessed the ability of the 3D imaging to detect myocardial scarring that was confirmed by late gadolinium enhancement MRI. Results The phantom study showed a good agreement for the T1 value between 2D and 3D Look-Locker MRI. There were no significant differences in the myocardial T1 values after contrast between 2D and 3D Look-Locker MRI or in the T1 values between the two imaging slices on the 3D Look-Locker MRI (P > 0.10). A better agreement for the myocardial T1 values was found when the 3D Look-Locker imaging was performed first. The T1 values for blood were affected by the scan order (P < 0.05). The 3D Look-Locker MRI showed myocardial scarring with a shorter T1 value (290.4 ± 62.7 ms) than those for unscarred myocardium (360.8±30.3 ms). Conclusion Three-dimensional Look-Locker MRI may precisely estimate the postcontrast myocardial and blood T1 values for the entire left ventricle during a single scan.

Contrast-enhanced Steady-state Free Precession in the Assessment of Hypertrophic Obstructive Cardiomyopathy after Alcohol Septal Ablation.

PURPOSE We evaluated the feasibility of contrast-enhanced steady-state free precession (ceSSFP) in the assessment of myocardial injury and obstruction of the left ventricular outflow tract (LVOT) in patients with hypertrophic obstructive cardiomyopathy (HOCM) after alcohol septal ablation (ASA). METHODS Twelve patients with HOCM underwent 16 magnetic resonance (MR) examinations following ASA. Precontrast SSFP, ceSSFP and late gadolinium enhancement (LGE) imaging were performed with a 1.5-tesla imager. ceSSFP was performed 3 to 7 min after gadolinium injection. We visually and quantitatively evaluated the signal patterns of the myocardium after ASA on SSFP and LGE MR imaging. We observed the LVOT using ceSSFP in the 3-chamber view. RESULTS We could visualize ASA-induced myocardial infarction (MI) in all 16 studies by LGE and ceSSFP but in only 6 studies (37.5%) by precontrast SSFP. Contrast was higher between MI and remote myocardium with LGE than ceSSFP (P < 0.01). ASA-induced hypointense regions were well visualized by the 2 sequences after contrast in the 7 patients who underwent MR imaging within 7 weeks of ASA and in a few patients after 80 weeks from ASA. The ceSSFP allowed comparable visualization of the jet flow crossing the LVOT to that derived from echocardiographic data. CONCLUSION Contrast-enhanced steady-state free precession allows assessment of myocardial injury as well as of the left ventricular outflow tract after alcohol septal ablation in a single scan without penalty in scan time and cine imaging contrast.