T1 mapping for myocardial extracellular volume measurement by CMR: bolus only versus primed infusion technique.

Abstract

OBJECTIVES:

The aim of this study was to determine the accuracy of the contrast "bolus only" T1 mapping cardiac magnetic resonance (CMR) technique for measuring myocardial extracellular volume fraction (ECV).

BACKGROUND:

Myocardial ECV can be measured with T1 mapping before and after contrast agent if the contrast agent distribution between blood/myocardium is at equilibrium. Equilibrium distribution can be achieved with a primed contrast infusion (equilibrium contrast-CMR [EQ-CMR]) or might be approximated by the dynamic equilibration achieved by delayed post-bolus measurement. This bolus only approach is highly attractive, but currently limited data support its use. We compared the bolus only technique with 2 independent standards: collagen volume fraction (CVF) from myocardial biopsy in aortic stenosis (AS); and the infusion technique in 5 representative conditions.

METHODS:

One hundred forty-seven subjects were studied: healthy volunteers (n = 50); hypertrophic cardiomyopathy (n = 25); severe AS (n = 22); amyloid (n = 20); and chronic myocardial infarction (n = 30). Bolus only (at 15 min) and infusion ECV measurements were performed and compared. In 18 subjects with severe AS the results were compared with histological CVF.

RESULTS:

The ECV by both techniques correlated with histological CVF (n = 18, r² = 0.69, p < 0.01 vs. r² = 0.71, p < 0.01, p = 0.42 for comparison). Across health and disease, there was strong correlation between the techniques (r² = 0.97). However, in diseases of high ECV (amyloid, hypertrophic cardiomyopathy late gadolinium enhancement, and infarction), Bland-Altman analysis indicates the bolus only technique has a consistent and increasing offset, giving a higher value for ECVs above 0.4 (mean difference ± limit of agreement for ECV <0.4 = -0.004 ± 0.037 vs. ECV >0.4 = 0.040 ± 0.075, p < 0.001).

CONCLUSIONS:

Bolus only, T1 mapping-derived ECV measurement is sufficient for ECV measurement across a range of cardiac diseases, and this approach is histologically validated in AS. However, when ECV is >0.4, the bolus only technique consistently measures ECV higher compared with infusion.

• Authors: Steven K White, Daniel M Sado, Marianna Fontana, Sanjay M Banypersad, Viviana Maestrini, Andrew S Flett, Stefan K Piechnik, Matthew D Robson, Derek J Hausenloy, Amir M Sheikh, Philip N Hawkins, James C Moon
• Journal: JACC. Cardiovascular imaging (JACC Cardiovasc Imaging) Vol. 6 Issue 9 Pg. 955-62 (Sep 2013) ISSN: 1876-7591 [Electronic] United States
• PMID: 23582361 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Chemical References

• Contrast Media
• Gadolinium DTPA

Topics

• Adult
• Aged
• Aged, 80 and over
• Biopsy
• Cardiomyopathy, Hypertrophic (diagnosis)
• Contrast Media
• Extracellular Matrix (pathology)
• Female
• Gadolinium DTPA
• Humans
• Magnetic Resonance Imaging, Cine (methods)
• Male
• Middle Aged
• Myocardium (pathology)
• Predictive Value of Tests
• Reproducibility of Results
• Young Adult