Influence of phase correction of late gadolinium enhancement images on scar signal quantification in patients with ischemic and non-ischemic cardiomyopathy

Background: myocardial fibrosis imaging using late gadolinium enhancement (lge) cardiac magnetic resonance (cmr) has been validated as a quantitative predictive marker for response to medical,surgical,and device therapy. to date,all such studies have examined conventional,non-phase corrected magnitude images. however,contemporary practice has rapdily adopted phase-corrected image reconstruction. we sought to investigate the existence of any systematic bias between threshold-based scar quantification performed on conventional magnitude inversion recovery (mir) and matched phase sensitive inversion recovery (psir) images. methods: in 80 patients with confirmed ischemic (n=40),or non-ischemic (n=40) myocardial fibrosis,and also in a healthy control cohort (n=40) without fibrosis,myocardial late enhancement was quantified using a signal threshold versus reference myocardium technique (strm) at ≥2,≥3,and ≥5 sd threshold,and also using the full width at half maximal (fwhm) technique. this was performed on both mir and psir images and values compared using linear regression and bland-altman analyses. results: linear regression analysis demonstrated excellent correlation for scar volumes between mir and psir images at all three strm signal thresholds for the ischemic (n=40,r=0.96,0.95,0.88 at 2,3,and 5 sd,p<0.0001 for all regressions),and non ischemic (n=40,r=0.86,0.89,0.90 at 2,3,and 5 sd,p<0.0001 for all regressions) cohorts. fwhm analysis demonstrated good correlation in the ischemic population (n=40,r=0.83,p<0.0001). bland-altman analysis demonstrated a systematic bias with mir images showing higher values than psir for ischemic (3.3 %,3.9 % and 4.9 % at 2,3,and 5 sd,respectively),and non-ischemic (9.7 %,7.4 % and 4.1 % at ≥2,≥3,and ≥5 sd thresholds,respectively) cohorts. background myocardial signal measured in the control population demonstrated a similar bias of 4.4 %,2.6 % and 0.7 % of the lv volume at 2,3 and 5 sd thresholds,respectively. the bias observed using fwhm analysis was -6.9 %. conclusions: scar quantification using phase corrected (psir) images achieves values highly correlated to those obtained on non-corrected (mir) images. however,a systematic bias exists that appears exaggerated in non-ischemic cohorts. such bias should be considered when comparing or translating knowledge between mir- and psir-based imaging. © 2015 stirrat et al. this is an open access article distributed under the terms of the creative commons attribution license.