Keywords:
Performed at one institution, Diagnostic or prognostic study, Prospective, Tissue characterisation, Hyperplasia / Hypertrophy, Imaging sequences, Contrast agent-intravenous, MR, Cardiac
Authors:
A. Cassar Scalia, L. Ruoli, F. Fiocchi, G. Ligabue, P. Torricelli; Modena/IT
DOI:
10.26044/ecr2020/C-13455
Methods and materials
Patient population. Fifty healthy subjects (32 subjects aged 18-65 and 18 subjects aged > 65) and ten patients with amyloidosis were prospectively recruited between February 2019 and October 2019. Four patients presented with the diagnosis of ATTR-amyloidosis proven by 99mTc-scintigraphy and six patients with suspected amyloidosis (two were first-degree relatives of a patient diagnosed with ATTRm amyloidosis, two were affected by hypertrophic cardiomyopathy, two presented with carpal tunnel syndrome). None of them had endomyocardial biopsy.
Data acquisition.CMR studies were performed using a 3T MR system (SIGNATM Architect by GE Healthcare Chicago, Illinois, USA) with gradients amplitude of 44 mT/m with a slew rate of 200 mT/m/ms. A 36-element receiver-coil (TDI Anterior Array) combined with a 59-elements receiver-coil (TDI Posterior Array) was used. Since April 2019 we have used AIRTM technology surface coils. The MRI protocol consisted of CINE-SSFP sequences acquired in different planes, fat suppressed T2-weighted sequence (STIR or ASPIR), late gadolinium enhancement (LGE) sequences acquired 12-20 minutes after contrast injection (Gadolinium-DOTA 0.2 ml/kg) in different planes. T1-mapping was performed using MOLLI sequence with 3(3)3(3)5 scheme, before and 15 minutes after contrast injection.
Data analysis. Native T1 and ECV were measured semi-automatically using a dedicated cardiac MR software (cvi42 software - Circle Cardiovascular Imaging Inc., Version 5.10, Calgary, Canada). For myocardial T1 analysis, epicardial and endocardial contours were drawn manually on the MOLLI mid-ventricular short axis. These contours were then expanded to all the sequences from basal to apical slices in order to obtain the curves expressing Native T1 values for the entire slice. The same process was then repeated for the slices of the post-contrast MOLLI T1-mapping. ECV was calculated at all post contrast time points by normalizing myocardial R1 change with blood R1 change and also correcting for hematocrit. The application of the algorithm resulted in the creation of the colorimetric pixel-based maps, one for native T1 values, one for post-contrast T1 values and one for the ECV. To simplify the graphic visualization and interpretation, we created a custom reference colorimetric scale based on found values (Fig.1, Fig.2).
Statistical analysis. The first objective of statistical analysis was to prove that calculated T1 values distribution generated a Gauss curve in order to find a range of reference values to use for further clinical application in our centre.
Secondly we compared, using T-test, the mean values of native T1 and ECV obtained in patients affected by amyloidosis with healthy subjects, evaluating diagnostic accuracy with ROC curves.
Finally we compared, using ANOVA test, these parameters obtained in the ATTR patients’ subgroup with other patients.