Paul de Heer MSc, Presenter: Nothing to Disclose

Maurice B Bizino, Abstract Co-Author: Nothing to Disclose

Andrew Webb DPHIL, Abstract Co-Author: Nothing to Disclose

Hildo J. Lamb MD, PhD, Abstract Co-Author: Nothing to Disclose

Cardiac 1H magnetic resonance spectroscopy (1H-MRS) is the gold standard for non-invasive quantification of myocardial triglyceride content (MTGC) which is a key feature of cardiomyopathy in metabolic syndrome and type 2 diabetes mellitus. 1H-MRS is a challenging technique due to a low signal-to-noise ratio (SNR), and the purpose of this study was to investigate whether high permittivity pads can increase the SNR, thereby also reducing the scanning time required.

All experiments were approved by the institutional Ethics Committee and written informed consent from all volunteers was obtained prior to the study. Twenty healthy volunteers were scanned, 8 female and 12 male, average age 30 yr. (range 19-53), average BMI of 23 kg/m2 (range 20-34). Scans were performed on a 3T Philips Ingenia. Two high permittivity pads, 2 cm thick (anterior) and 1cm thick (posterior), with dimensions 20x20cm2 were used. The spectroscopic volume-of-interest (40x15x25mm3) was planned in the interventricular septum. ECG-triggered respiratory navigated PRESS spectra were acquired without water suppression (TE 35ms, TR 8.5s, 16 averages) and with water suppression (TE 35ms, TR 3.5s, 48 averages) with and without dielectric pads. Data were phase and DC corrected, and fitted using the AMARES algorithm in jMRUI. The SNR of the TG spectra was defined as the integrated area under the (CH2)n and (CH3) peak divided by the SD of the noise taken from the last 100 points of the FID. Statistical significance of the data was tested using a double sided paired Student’s t–test and was considered significant at p-values < 0.05.

In Fig. 1 spectra from two different volunteers and a summary Bland-Altman plot is shown. The mean lipid SNR for all volunteers show an increase from 28±16 (mean±SD) to 42±24 (p<0.0001), a gain factor in SNR of 1.6±0.5 when the pads are used. The average MTGC is 0.39% without pads and 0.38% with pads, showing no significant difference. 

High permittivity materials improve cardiac 1H-MR spectroscopy at 3T by increasing SNR by a factor of 1.6, resulting in better quantification and/or a reduction in acquisition time by a factor of ~2.6 (gain_SNR*gain_SNR).

Cardiac 1H MR spectroscopy is a unique non-invasive method to assess cardiac energy metabolism. The innovation of using high permittivity materials increases the accuracy and speed of the technique.

de Heer, P, Bizino, M, Webb, A, Lamb, H, Fast Cardiac 1H-MR Spectroscopy at 3T: High Permittivity Materials Increase SNR and Reduce Data Acquisition Time.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011380.html