T₁ mapping for assessment of myocardial injury and microvascular obstruction at one week post myocardial infarction

Donnie Cameron, Nishat Siddiqi, Christopher J Neil, Baljit Jagpal, Margaret Bruce, David M Higgins, Jiabao He, Satnam Singh, Thomas W Redpath, Michael P Frenneaux, Dana K Dawson

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Abstract

OBJECTIVES: To compare 3T T1 mapping to conventional T2-weighted (T2W) imaging for delineating myocardial oedema one week after ST-elevation myocardial infarction (STEMI), and to explore the confounding effects of microvascular obstruction (MVO) on each technique. 

METHODS: T2W spectral attenuated inversion recovery and native T1 mapping were applied in 10 healthy volunteers and 62 STEMI patients, and late gadolinium enhancement was included for infarct localisation at 1 week and at 6 months post-STEMI. Segmental T1 values and T2W signal intensity ratios were calculated; oedema volumes and salvage indices were determined in patients using image thresholding-a receiver operator characteristic (ROC) derived T1 threshold, and a 2SD T2W threshold; and the results were compared between patients with/without MVO (n=35/27). 

RESULTS: Native T1 mapping delineated oedema with significantly better discriminatory power than T2W-as indicated by ROC analysis (area-under-the-curve, AUC=0.89 versus 0.83, p=0.009; and sensitivity/specificity=83/83% versus 73/73%). The optimal ROC threshold derived for T1 mapping was 1241ms, which gave significantly larger oedema volumes than 2SD T2W (p=0.006); with this threshold, patients with and without MVO showed similar oedema volumes, but patients with MVO had significantly poorer salvage indices (p<0.05) than those without. Neither method was significantly affected by MVO, the volume of which was seen to increase exponentially with infarct size. 

CONCLUSIONS: Native T1 mapping at 3T can delineate oedema one week post-STEMI, showing larger oedema volumes and better discriminatory power than T2W imaging, and it is suitable for quantitative thresholding. Both techniques are robust against MVO-related magnetic susceptibility.

Original languageEnglish
Pages (from-to)279-285
Number of pages7
JournalEuropean Journal of Radiology
Volume85
Issue number1
Early online date23 Oct 2015
DOIs
Publication statusPublished - Jan 2016

Keywords

  • Acute myocardial infarction
  • Magnetic resonance imaging
  • Myocardium at risk
  • Myocardial oedema
  • Microvascular obstruction
  • T1 mapping

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