To evaluate whether the new magnetic resonance imaging (MRI) technique related to T1 weighted black blood (T1W BB) signal intensity difference ratio between pre- and post- gadolinium contrast injection can serve as a potential technique for use in differentiating normal and diseased myocardium involving the increasing myocardial extracellular volume (ECV) in terms of sensitivity, specificity and accuracy in comparison with late gadolinium contrast enhancement (LGE) MRI technique.
A retrospective analysis was conducted for a pilot of a total of 14 patients with known and suspected myocardial disease who underwent a cardiovascular magnetic resonance (CMR) scan at Bangkok Heart Hospital, Bangkok, Thailand in the period from September 2016-April 2017. LGE MRI and Spin echo T1W BB MRI in both pre- and post- contrast injection were performed in all patents on short axis view in the same slice position and number of slices. The myocardial signal intensity measurement on the T1W BB in both pre- and post- contrast injection images were acquired on short axis view at the same region of interest (contrast enhancement region and negative enhancement) on LGE MRI images. T1 signal intensity difference ratio (SDR) between pre- and post- contrast were calculated in both LGE positive and negative groups. The mean T1W BB signal intensity difference ratio value > 30% was classified as abnormal increased ECV myocardium.
The 14 study population have a mean age of 53.3±11.5 and are 64% male. Five were normal patients with negative LGE and nine were found to have myocardial disease with positive LGE. A total of 61 sample slices on short axis view of the ventricle of each T1W BB pre- and post- contrast were obtained from all patients, 31 of 61 were from diseased myocardium with LGE positive scan and 30 were from normal myocardium with a LGE negative scan. A myocardial T1 signal difference ratio > 30% was found in 2 of 30 slices of normal myocardium with the LGE negative group and 31 of 31 slices of the LGE positive group. The mean signal difference ratio value of normal and diseased myocardium were 19.13±7.5 % and 41.4±7.6% respectively. The sensitivity and specificity and the accuracy of T1W BB difference ratio > 30% in differentiating normal from myocardium with involving increasing ECV were 100%, 93.3% and 96.7% (p=0.72) consecutively compared to the LGE MRI.
The use of T1W BB in assessing myocardial diseases with either a focal or diffuse involvement demonstrates a higher value ratio of extracellular space pre- and post- contrast study of more than 30% indicating myocardial disease with 100% sensitivity and 93.3% in specificity and 96.7% accuracy that is shown to be comparable to gold standard LGE technique in detecting focal increasing myocardial ECV by statistic chi-square test p =0.72 (not less than 0.05)
myocardium, extracellular volume (ECV), late gadolinium enhancement (LGE), MRI, T1 weighted black blood (T1W BB), Signal intensity (SI), Signal intensity difference