Study selection
The history of old myocardial infarction was criteria of prospective selection for dedicated CMR protocol.
Retrospective,
LCE sequences was used for confirmation of transmural lesion and wall thickness,
was used for confirmation of chronic lesion.
The adequate breath hold capability and normal sinus cardiac pace also was considered,
in order to have a good image quality.
Finally in this study were included 51 patients (56 ± 9 y),
with good image quality.
All the studies were performed according to the guidelines of the institution board on medical ethics and clinical investigation.
Informed consent was obtained from each patient.
Study protocol
All CMR examinations were performed on a 3T MR system (Magnetom Skyra 3T,
syngo MR D13,
Siemens Medical Solution).
An adapted protocol was used for optimal imaging quality and fast speed acquisition.
Imaging protocol included: (1) Scouts for auto table detection,
2nd order shim adjustments,
optimal ∆ frequency selection,
and cardiac views localizers; (2) vertical long axis (VLA) and horizontal long axis (HLA) views non-contrast cine images; (3) short axis (SAX) CE-cine images; (4) HLA,
VLA and SAX imaging for late contrast enhancement (LCE).
Non-contrast cine and CE-cine images were acquired using 2nd order shim and ∆frequency adjustments in order to avoid off-set and susceptibility artifacts.
Were used following parameters: TR 37.18 / TE 1.16,
flip angle 80,
FOV 360mm,
FOV phase 75%,
phase oversampling 30%,
matrix 153x240,
slice thickness 7mm,
slice gap 0mm,
>25 phase per slice,
according to the heart rate,
acceleration factor 3 (iPAT mode),
ECG retrospective acquisition.
CE-cine SAX images were acquired after 2 min,
following i/v contrast administration of 0.2 mmol/kg of gadodiamide (Omniscan).
For LCE were used b-SSFP phase sensitive inversion recovery (PSIR) sequence,
with following parameters: TR 715 / TE 3.05,
flip angle 25,
FOV 360mm,
FOV phase 75%,
phase oversampling 30%,
matrix 168x240,
slice thickness 7 mm,
slice gap 0mm,
acceleration factor 2 (iPAT mode),
inversion time 350ms,
ECG prospective multi shot acquisition. Images were acquired after 10min,
following contrast administration.
Total scanning time ~15 - 20min.
Data interpretation
For image analysis dedicated evaluation software was used (Osirix MD,
V 6.5.2).
To ensure accurate evaluation of image appearances on cine and CE-cine,
LCE served for location of normal myocardium and transmural scar (merged images).
Signal intensity (SI) was appreciated using a region of interest (ROI) in cavity,
normal myocardium and transmural scar.
The ROI on the b-SSFP images before contrast administration was chosen on VLA and HLA views corresponding the regions of interest on the CE-cine in SAX view.
The relative contrast ratio (rCR) between blood and normal myocardium,
blood and transmural scar,
and between normal myocardium and transmural scar was calculated by dividing the respective SI.
The absolute contrast ratio (aCR) was calculated by subtracting the mean SI of respective ROI.
Statistical analysis
Categorical variables were expressed as mean ± SD or median (25th-75th percentiles) as appropriate.
Student T - test was used to compare continuous variable differences between patients.