T1 mapping for myocardial extracellular volume measurement by cardiovascular magnetic resonance: bolus only vs primed infusion technique
Journal of Cardiovascular Magnetic Resonance volume 15, Article number: O14 (2013)
Myocardial ECV can be measured using T1 mapping before and after contrast if the contrast agent distribution between blood:myocardial is at equilibrium. Equilibrium distribution can be achieved with a primed contrast infusion (EQ-CMR), or may 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 two gold standards: collagen volume fraction (CVF) from myocardial biopsy in aortic stenosis (AS), and the infusion technique in five representative conditions.
147 subjects were studied: healthy volunteers (n=50); hypertrophic cardiomyopathy (HCM, n=25); severe AS (n=22); amyloid (n=20); and chronic myocardial infarction (n=30). Bolus only (at 15 minutes) and infusion ECV measurements were performed and compared. In 18 subjects with severe AS the results were compared to histological CVF.
ECV by bolus only technique correlated well with CVF (n=18, r2=0.56, p=<0.01) but the r2 was higher with the infusion technique (r2=0.71, p=<0.01). Across health and disease, there was high correlation between the techniques (r2=0.97). However, in diseases of high ECV (amyloid, HCM LGE, and infarction), Bland-Altman analysis indicates the bolus only technique consistently and increasingly overestimates ECV.
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 above 0.4, there is overestimation compared to the infusion approach.
British Heart Foundation.
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White, S.K., Sado, D., Fontana, M. et al. T1 mapping for myocardial extracellular volume measurement by cardiovascular magnetic resonance: bolus only vs primed infusion technique. J Cardiovasc Magn Reson 15 (Suppl 1), O14 (2013). https://doi.org/10.1186/1532-429X-15-S1-O14