Normal myocardial native T1 values in children using single-point saturation recovery and modified look-locker inversion recovery (MOLLI)

Normal Ventricular and Regional Blood Flow Volumes and Native T1 Values in Healthy Japanese Children Obtained from Comprehensive Cardiovascular Magnetic Resonance Imaging

Age-related mean and reference ranges for ventricular volumes and mass, regional blood flow measurements, and T1 values using cardiovascular magnetic resonance (CMR) imaging are yet to be established for the pediatric population. Especially in infants and toddlers, no consistent flow volume sets or T1 values have been reported. The purpose of this study was to determine the relevant normal values.Twenty-three children (aged 0.1-15.3 years) without cardiovascular diseases were included. Comprehensive CMR imaging including cine, 2-dimensional phase-contrast, and native T1 mapping, were performed. Ventricular volumes and masses, 11 sets of regional blood flow volumes, and myocardial and liver T1 values were measured. All intraclass correlation coefficient values were > 0.94, except for the right ventricular mass (0.744), myocardial (0.868) and liver T1 values (0.895), reflecting good to excellent agreement between rates.Regression analysis showed an exponential relationship between body surface area (BSA) and ventricular volumes, mass, and regional blood flow volumes (normal value = a*BSAb). Left ventricular myocardial T1 values were regressed on linear regression with age (normal value = -7.39*age + 1091), and hepatic T1 values were regressed on a quadratic function of age (normal value = 0.923*age2 -18.012*age + 613).Comparison of the 2 different methods for the same physical quantities by Bland-Altman plot showed no difference except that the right ventricular stroke volume was 1.5 mL larger than the main pulmonary trunk flow volume.This study provides the normal values for comprehensive CMR imaging in Japanese children.

Cardiac magnetic resonance imaging: insights into developmental programming and its consequences for aging

Cardiovascular diseases (CVD) are important consequences of adverse perinatal conditions such as fetal hypoxia and maternal malnutrition. Cardiac magnetic resonance imaging (CMR) can produce a wealth of physiological information related to the development of the heart. This review outlines the current state of CMR technologies and describes the physiological biomarkers that can be measured. These phenotypes include impaired ventricular and atrial function, maladaptive ventricular remodeling, and the proliferation of myocardial steatosis and fibrosis. The discussion outlines the applications of CMR to understanding the developmental pathways leading to impaired cardiac function. The use of CMR, both in animal models of developmental programming and in human studies, is described. Specific examples are given in a baboon model of intrauterine growth restriction (IUGR). CMR offers great potential as a tool for understanding the sequence of dysfunctional adaptations of developmental origin that can affect the human cardiovascular system.

Pediatric Myocardial T1 and T2 Value Associations with Age and Heart Rate at 1.5 T

The objective of the study was to determine normal global left ventricular reference values for T1 and T2 in children. This is a retrospective study that included healthy subjects, age 5-19 years, who underwent CMR for the indication of pectus excavatum from 2018 to 2019. Linear regression models were used to determine associations of native T1 and T2 values to heart rate, age, and other CMR parameters. 102 patients with a mean age of 14.0 ± 2.4 years were included (range 5.4-18.8). 87 (85%) were males and 15 (15%) were females. The mean global T1 was 1018 ± 25 ms and the mean T2 was 53 ± 3 ms. T1 was negatively correlated with age (r = - 0.39, p < 0.001) and positively correlated with heart rate (r = 0.32, p < 0.001) by univariate analysis. Multivariable analysis showed that age and heart rate were independently associated with T1. T2 demonstrated a weak negative correlation with age (r = - 0.20, p = 0.047) and no correlation with heart rate. There was no difference in T1 (p = 0.23) or T2 (p = 0.52) between genders. This study reports normal pediatric T1 and T2 values at a 1.5 Tesla scanner. T1 was dependent on age and heart rate, while T2 was less dependent on age with no correlation with heart rate.

Myocardial T1 mapping using SMART1 Map and MOLLI mapping in asymptomatic patients with recent extracardiac sarcoidosis

INTRODUCTION

Sarcoidosis is a systemic granulomatous disease affecting in particular the respiratory tract. Cardiac magnetic resonance (CMR), including a measurement of T₁ relaxation time, could potentially detect early stadia of sarcoidosis of the heart. The study aims to assess T₁ mapping in the detection of early cardiac involvement in asymptomatic patients with sarcoidosis.

METHODS

One hundred and twenty patients with extracardiac sarcoidosis and without any heart disease history were included. One hundred and thirteen of them underwent a CMR examination. The mean time from the diagnosis of sarcoidosis was 0.8 (0.2-3.3) years. Cine images for the assessment of left ventricular (LV) functional parameters and pre- and post-contrast saturation method using adaptive recovery times for cardiac T₁ mapping (SMART₁ Map) and modified Look-Locker inversion recovery (MOLLI) images were acquired for the assessment of native T₁ relaxation time and extracellular volume (ECV). The measured parameters were compared between sarcoidosis patients and 22 controls.

RESULTS

The sarcoidosis patients had normal global and regional systolic LV function-LV ejection fraction 65 ± 5% versus 66 ± 7% (p NS). The mean native T₁ relaxation times were not prolonged-1465 ± 93 ms versus 1480 ± 88 ms (p NS) measured by SMART₁ Map and 1317 ± 60 ms versus 1313 ± 83 ms (p NS) measured using a MOLLI sequence. Similarly, the mean ECV values did not increase-16.9 ± 3.9% versus 17.9 ± 3.7% (p NS) measured by SMART₁ Map and 30.9 ± 2.9% versus 31.6 ± 8.3% (p NS) measured using a MOLLI sequence.

CONCLUSION

Myocardial native T₁ relaxation times were not prolonged and ECV was not increased in asymptomatic patients with extracardiac sarcoidosis.

Normative Data for Myocardial Native T1 and Extracellular Volume Fraction in Children

Purpose

To establish normative data for myocardial T1, including extracellular volume (ECV) fraction, in healthy children.

Materials and Methods

In this retrospective, single-center study, T1 mapping data were collected from 48 healthy pediatric patients (14 years ± 3 [standard deviation]; range, 9-18 years; 27 of 48 [56%] male) referred for cardiac screening 1.5-T MRI between 2014 and 2017. T1 relaxometry was performed using a 5(number of heartbeats [nHB])3 modified Look-Locker inversion recovery (MOLLI) sequence, where nHB was three to five heartbeats depending on the heart rate, and was repeated 15 minutes following the administration of 0.2 mmol per kilogram of body weight of gadobenate dimeglumine, with 19 patients receiving contrast material. T1 values were calculated using a curve-fitting algorithm on average region-of-interest signal and corrected for imperfect inversion pulse efficiency. Comparisons within patients were performed with paired Student t test, between groups with unpaired Student t test or Mann-Whitney U test, and linear regression was performed to examine for associations with other variables.

Results

Average native T1 was 1008 msec ± 31, with a nonsignificant increase in females (1017 msec ± 27 vs 1001 msec ± 33, P = .066). Average ECV was 20.8% ± 2.4, with a nonsignificant increase in values in females (21.7% ± 1.9 vs 20.0% ± 2.6, P = .123). T1 and ECV values were increased in the septum versus the free wall.

Conclusion

Normative data are presented for myocardial native T1 and ECV using the MOLLI T1 mapping sequence at 1.5 T.Supplemental material is available for this article.© RSNA, 2020.

Cardiac MRI in Children with Multisystem Inflammatory Syndrome Associated with COVID-19

This case series examines cardiac MRI findings in four children and adolescents admitted to intensive care in April 2020 for multisystem inflammatory syndrome and Kawasaki disease-like features related to COVID-19. Acute myocarditis occurred less than 1 week after onset of fever and gastrointestinal symptoms. Physical examination showed rash and cheilitis/conjunctivitis. All patients recovered after intravenous immunoglobulin therapy. SARS-CoV-2 RT-PCR was negative on nasopharyngeal, stool, and respiratory samples and was positive on serology. Cardiac MRI showed diffuse myocardial edema on T2-STIR sequences and native-T1 mapping, with no evidence of late gadolinium enhancement suggestive of replacement fibrosis or focal necrosis. These findings favor post-infectious myocarditis in children and adolescents with COVID-19.