[Effects of Heart Rate on Myocardial Native T1 Value Acquired by 5s(3s)3s MOLLI Sequence].

Quantitative evaluation of myocardial native T1 value by measuring modified Look-Locker inversion recovery (MOLLI) method is clinically useful and is used for follow-up of various myocardial diseases. The heart rate during the scan can vary even in the same subjects. Therefore, it is important to know the effects of the heart rate on the native T1 value of the myocardium. In this study, we evaluated the effect of the heart rate on the T1 value in the 5s (3s) 3s scheme, time control data collection period of the MOLLI method, using phantom experiments and experiments of healthy volunteers. The 5s (3s) 3s scheme of the MOLLI method is considered to have little dependence on the heart rate, but the T1 value still varied up to about 7% depending on the heart rate, and was underestimated up to 8% during low heart rate using phantom experiments.

Clinical Importance of Myocardial T2 Mapping and Texture Analysis.

Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) is valuable for diagnosis and assessment of the severity of various myocardial diseases owing to its potential to visualize myocardial scars. T1 mapping is complementary to LGE because it can quantify the degree of myocardial fibrosis or edema. As such, T1-weighted imaging techniques, including LGE using an inversion recovery sequence, contribute to cardiac MRI. T2-weighted imaging is widely used to characterize the tissue of many organs. T2-weighted imaging is used in cardiac MRI to identify myocardial edema related to chest pain, acute myocardial diseases, or severe myocardial injuries. However, it is difficult to determine the presence and extent of myocardial edema because of the low contrast between normal and diseased myocardium and image artifacts of T2-weighted images and the lack of an established method to quantify the images. T2 mapping quantifies myocardial T2 values and help identify myocardial edema. The T2 values are significantly related to the clinical symptoms or severity of nonischemic cardiomyopathy. Texture analysis is a postprocessing method to quantify tissue alterations that are reflected in the T2-weighted images. Texture analysis provides a variety of parameters, such as skewness, entropy, and grey-scale non-uniformity, without the need for additional sequences. The abnormal signal intensity on T2-weighted images or T2 values may correspond to not only myocardial edema but also other tissue alterations. In this review, the techniques of cardiac T2 mapping and texture analysis and their clinical relevance are described.

Wafer-Scale Growth of One-Dimensional Transition-Metal Telluride Nanowires.

The development of bulk synthetic processes to prepare functional nanomaterials is crucial to achieve progress in fundamental and applied science. Transition-metal chalcogenide (TMC) nanowires, which are one-dimensional (1D) structures having three-atom diameters and van der Waals surfaces, have been reported to possess a 1D metallic nature with great potential in electronics and energy devices. However, their mass production remains challenging. Here, a wafer-scale synthesis of highly crystalline transition-metal telluride nanowires is demonstrated by chemical vapor deposition. The present technique enables formation of either aligned, atomically thin two-dimensional (2D) sheets or random networks of three-dimensional (3D) bundles, both composed of individual nanowires. These nanowires exhibit an anisotropic 1D optical response and superior conducting properties. The findings not only shed light on the controlled and large-scale synthesis of conductive thin films but also provide a platform for the study on physics and device applications of nanowire-based 2D and 3D crystals.

Detection of Myocardial Tissue Alterations in Hypertrophic Cardiomyopathy Using Texture Analysis of T2-Weighted Short Inversion Time Inversion Recovery Magnetic Resonance Imaging.

OBJECTIVE: The aim of this study was to evaluate the usefulness of texture analysis of T2-weighted short inversion time inversion recovery (T2-STIR) for detecting myocardial tissue alterations in hypertrophic cardiomyopathy (HCM). METHODS: Twenty patients with HCM and 11 controls were examined. Texture analysis was performed for the hypertrophied regions with and without and abnormal hyperintensity (AHI) and for the interventricular septum of the controls on T2-STIR. T2 mapping was performed to measure myocardial T2 values. RESULTS: A gray-level nonuniformity value of 64.7 was the best discriminator between patients and controls with an area under the curve of 0.93 on a receiver operating characteristic curve. T2 values did not differ between them. The gray-level nonuniformity was significantly smaller in AHI regions than in the hypertrophied regions without AHI in HCM patients. CONCLUSIONS: Texture analysis is useful for quantitatively detecting myocardial tissue altenations, including AHI, associated with HCM on T2-STIR.

Relationship between Measurement Errors in Myocardial T1 Mapping and Heart Rate.

PURPOSE: Modified Look-Locker inversion recovery (MOLLI) using a 5s(3s)3s scheme is robust to tachycardia, but some errors are occasionally observed in myocardial T1 mapping. We sought to evaluate the relationship between measurement errors in T1 mapping and heart rate (HR) using a confidence map. METHODS: We enrolled 69 male patients with normal native T1 values of the septal myocardium measured by a 5s(3s)3s MOLLI. The degree of measurement errors in the septal myocardium was assessed by two independent observers on a confidence map using a 4-point scale: 0, no errors; 1, errors located on the myocardial contour; 2, errors extended into the myocardial contour; and 3, errors extended into the midwall. We compared the scores of measurement errors and the average, maximum, minimum or variability of the HR indicated during the MOLLI scan (iHR), image phases of MOLLI or left ventricular ejection fraction (LVEF). RESULTS: Patients with score >1 for the septal myocardium had significantly lower minimum iHR than those with a score ≤1 (P < 0.01; 49.8 ± 10.1 vs. 59.6 ± 9.7 beat per min). CONCLUSION: The confidence map shows more measurement errors in patients with lower minimum iHR. The myocardial T1 values should be measured carefully in patients with bradycardia during MOLLI scanning.