BackgroundT1 mapping allows direct in-vivo quantitation of microscopic changes in the myocardium, providing new diagnostic insights into cardiac disease. Existing methods require long breath holds that are demanding for many cardiac patients. In this work we propose and validate a novel, clinically applicable, pulse sequence for myocardial T1-mapping that is compatible with typical limits for end-expiration breath-holding in patients.Materials and methodsThe Shortened MOdified Look-Locker Inversion recovery (ShMOLLI) method uses sequential inversion recovery measurements within a single short breath-hold. Full recovery of the longitudinal magnetisation between sequential inversion pulses is not achieved, but conditional interpretation of samples for reconstruction of T1-maps is used to yield accurate measurements, and this algorithm is implemented directly on the scanner. We performed computer simulations for 100 ms

Extracellular volume fraction imaging can quantitatively characterize myocardial infarction, atypical diffuse fibrosis, and subtle myocardial abnormalities not clinically apparent on LGE images. Taken within the context of prior literature, these subtle ECV abnormalities are consistent with diffuse fibrosis related to age and changes remote from infarction.

Purpose:To optimize and validate a fully-integrated version of modified Look-Locker inversion-recovery (MOLLI) for clinical single-breathhold cardiac T1 mapping. Materials and Methods:A MOLLI variant allowing direct access to all pulse sequence parameters was implemented on a 1.5T MR system. Varying four critical sequence parameters, MOLLI was performed in eight gadolinium-doped agarose gel phantoms at different simulated heart rates. T1 values were derived for each variant and compared to nominal T1 values. Based on the results, MOLLI was performed in midcavity short-axis views of 20 healthy volunteers preand post-Gd-DTPA. Results:In phantoms, a readout flip angle of 35°, minimum TI of 100 msec, TI increment of 80 msec, and use of three pausing heart cycles allowed for most accurate and least heart rate-dependent T1 measurements. Using this pulse sequence scheme in humans, T1 relaxation times in normal myocardium were comparable to data from previous studies, and showed narrow ranges both pre-and postcontrast without heart rate dependency. Conclusion:We present an optimized implementation of MOLLI for fast T1 mapping with high spatial resolution, which can be integrated into routine imaging protocols. T1 accuracy is superior to the original set of pulse sequence parameters and heart rate dependency is avoided. IN CONTRAST TO most cardiac imaging modalities, cardiac magnetic resonance is able not only to assess cardiac function, but also to directly detect structural changes within the myocardium. T1 mapping holds important potential to visualize and assess such structural changes in a quantitative fashion. For example, T1 measurements have been used to characterize myocardial infarction (1,2), cardiac amyloidosis (3) and systemic lupus erythematosus (4). Therefore, a robust and reproducible technique for cardiac T1 mapping both pre-and postcontrast would be desirable.Standard approaches for parametric mapping of T1 relaxation times such as the Look-Locker method (5,6) employ a continuous acquisition of image data and therefore are not suitable for cardiac applications, because cardiac motion causes a significant displacement of cardiac structures during image acquisition. Recently, modified Look-Locker inversion-recovery (MOLLI) has been proposed as a strategy to circumvent these timing problems (7). In contrast to conventional Look-Locker, MOLLI uses electrocardiogram (ECG)-gated image acquisition at end-diastole and merges images from three consecutive inversion-recovery experiments into one data set. With this approach, image data for single-slice T1 mapping of the heart can be acquired at high spatial resolution (approximately 2.0 ϫ 2.0 mm in-plane) within one breathhold of the subject. In phantom and volunteer studies it has been shown that the resulting T1 maps provide good T1 accuracy and high reproducibility (8), respectively, over a wide range of T1 covering both pre-and postcontrast situations. In the original implementation of MOLLI, the three inversionrecovery experiments required separate setup pro...

Background-Extracellular matrix expansion is a key element of ventricular remodeling and a potential therapeutic target. Cardiovascular magnetic resonance (CMR) T 1 -mapping techniques are increasingly used to evaluate myocardial extracellular volume (ECV); however, the most widely applied methods are without histological validation. Our aim was to perform comprehensive validation of (1) dynamic-equilibrium CMR (DynEq-CMR), where ECV is quantified using hematocrit-adjusted myocardial and blood T 1 values measured before and after gadolinium bolus; and (2) isolated measurement of myocardial T 1 , used as an ECV surrogate. Methods and Results-Whole-heart histological validation was performed using 96 tissue samples, analyzed for picrosirius red collagen volume fraction, obtained from each of 16 segments of the explanted hearts of 6 patients undergoing heart transplantation who had prospectively undergone CMR before transplantation (median interval between CMR and transplantation, 29 days). DynEq-CMR-derived ECV was calculated from T 1 measurements made using a modified Look-Locker inversion recovery sequence before and 10 and 15 minutes post contrast. In addition, ECV was measured 2 to 20 minutes post contrast in 30 healthy volunteers. There was a strong linear relationship between DynEq-CMR-derived ECV and histological collagen volume fraction (P<0.001; within-subject: r=0.745; P<0.001; r 2 =0.555 and betweensubject: r=0.945; P<0.01; r 2 =0.893; for ECV calculated using 15-minute postcontrast T 1 ). Correlation was maintained throughout the entire heart. Isolated postcontrast T 1 measurement showed significant within-subject correlation with histological collagen volume fraction (r=−0.741; P<0.001; r 2 =0.550 for 15-minute postcontrast T 1 ), but between-subject correlations were not significant. DynEq-CMR-derived ECV varied significantly according to contrast dose, myocardial region, and sex. Conclusions-DynEq-CMR-derived