Bettina Baessler MD, Presenter: Nothing to Disclose

Christian Stehning, Abstract Co-Author: Employee, Koninklijke Philips NV

Frank Schaarschmidt, Abstract Co-Author: Nothing to Disclose

Bernhard Schnackenburg PhD, Abstract Co-Author: Employee, Koninklijke Philips NV

David Christian Maintz MD, Abstract Co-Author: Nothing to Disclose

Alexander Christian Bunck, Abstract Co-Author: Nothing to Disclose

One of the main challenges of the T2-mapping technique is the high variability of the T2 relaxation times leading to difficulties in discriminating “still physiologic” from “already pathologic” in the case of myocardial edema. As the T2 relaxation times vary significantly depending on field strength, sequence and other influence factors, the purpose of this study was to compare three different T2-mapping sequences at 1.5T and 3T in healthy volunteers (HV) and to investigate the influence of cofactors on the T2 relaxation times.

Until today, we enrolled 16 HV. Each HV was examined on a clinical 1.5T and 3T scanner in immediate succession in the morning. A third scan was performed on the 1.5T scanner in the evening of the same day. In each examination three different T2-mapping sequences were performed at a basal, midventricular and apical slice in short axis view: Multi Echo Spin Echo (MESE), T2-prepared balanced Steady State Free Precession (T2prep; Giri et al., 2009) and Gradient Spin Echo (GraSe). Segmented T2-Maps were generated for each slice according to the AHA 17-segment model.

The cofactor “heart rate” proved to have significant impact on the measured T2 relaxation times. Therefore, correction for this cofactor was performed for all further statistical analyses. Significantly lower T2 relaxation times were observed between the T2prep sequence and all other sequences at 3T (p < 0.001) and at 1.5T (p < 0.05 for T2prep vs. MESE and p < 0.001 for T2prep vs. GraSe). The GraSe sequence resulted in significantly higher T2 relaxation times compared to MESE at 3T (p < 0.005) and at 1.5T (p < 0.001). Comparing T2 relaxation times between 1.5 and 3T significant differences were found for T2prep and GraSe (p < 0.001). No significant daytime variations were observed between the morning and evening scans.

The evaluation of different T2 mapping sequences at 1.5 and 3T in the heart of healthy volunteers represents a systematic approach to cardiac T2-mapping and underlines the need for dedicated reference maps for each sequence and field strength, as well as the need for a correction of the cofactor “heart rate”.

Myocardial edema is an important factor in several cardiac diseases. Cardiac T2-mapping promises to be a quantitative approach in edema imaging, overcoming some limitations of qualitative edema assessment.

Baessler, B, Stehning, C, Schaarschmidt, F, Schnackenburg, B, Maintz, D, Bunck, A, A Systematic Evaluation of Three Different Cardiac T2-mapping Sequences at 1.5 and 3T in Healthy Volunteers.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010939.html