Relationship between Measurement Errors in Myocardial T1 Mapping and Heart Rate

High-resolution systolic T1 mapping with compressed sensing for the evaluation of the right ventricle: a phantom and volunteer study

To investigate the usefulness of high-resolution systolic T1 mapping using compressed sensing for right ventricular (RV) evaluation. Phantoms and normal volunteers were scanned at 3 T by using a high-resolution (HR) modified look-locker inversion recovery (MOLLI) pulse sequence and a conventional MOLLI pulse sequence. The T1 values of the left ventricular (LV) and RV myocardium and blood pool were measured for each sequence. T1 values of HR-MOLLI and MOLLI sequences were compared in the LV myocardium, blood pool, and RV myocardium. The T1 values of HR-MOLLI and MOLLI showed good agreement in both phantoms and the LV myocardium and blood pool of volunteers. However, there was a significant difference between HR-MOLLI and MOLLI in the RV myocardium (1258 ± 52 ms vs. 1327 ± 73 ms; P = 0.0005). No significant difference was observed between the T1 value of RV and that of LV (1217 ± 32 ms) in HR-MOLLI, whereas the T1 value of RV was significantly higher than that of LV in MOLLI (P < 0.0001). The interclass correlation coefficients of intraobserver variabilities from HR-MOLLI and MOLLI were 0.919 and 0.804, respectively, and the interobserver variabilities from HR-MOLLI and MOLLI were 0.838 and 0.848, respectively. Assessment of RV myocardium by using HR systolic T1 mapping was superior to the conventional MOLLI sequence in terms of accuracy and reproducibility.

Quantitative abdominal magnetic resonance imaging in children-special considerations

The use of quantitative MRI methods for assessment of the abdomen in children has become commonplace over the past decade. Increasingly employed methods include MR elastography, chemical shift encoded (CSE) MR imaging for determination of proton density fat fraction, diffusion-weighted imaging, and a variety of relaxometry techniques, such as T1 and T2* mapping. These techniques can be used in a variety of settings to distinguish normal from abnormal tissue as well as determine the severity of disease. The performance of quantitative MRI methods in the pediatric population presents unique challenges as compared to adult populations. These challenges relate to multiple factors, including patient size, pediatric physiology, inability to breath hold, and greater physical motion during the examination. The purpose of this review article is to review quantitative MRI methods that may be used in clinical practice to assess the pediatric abdomen and to discuss special considerations when performing these techniques in children.