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Published on: July 19, 2013
Phase-sensitive inversion-recovery MR imaging in the detection of myocardial infarction
Armin M Huber1, Stefan O Schoenberg, Carmel Hayes
1Institute for Clinical Radiology, Clinic of Ludwig-Maximilians-University Munich, Grosshadern, Marchioninistr 15, 81377 Munich, Germany. armin.huber@med.uni-muenchen.de
Purpose:
To prospectively determine if phase-sensitive inversion-recovery (IR) magnetic resonance (MR) imaging eliminates the need to find the precise inversion time (TI) to null the signal of normal myocardium to achieve high contrast between infarcted and normal myocardium.
Materials And Methods:
Informed consent was obtained from each patient for this prospective MR imaging research study, which was approved by the institutional review board. Twenty patients (16 men; four women; mean age, 56 years +/- 12.3) who experienced Q-wave myocardial infarction 2 weeks earlier were examined with a 1.5-T MR system 10 minutes after administration of 0.1 mmol per kilogram of body weight gadobenate dimeglumine. To determine the optimal TI, a TI scout sequence was used. A segmented two-dimensional IR turbo fast low-angle shot (FLASH) sequence and a segmented two-dimensional IR true fast imaging with steady-state precession (FISP) sequence that produces both phase-sensitive and magnitude-reconstructed images were used at TI values of 200-600 msec (TI values were varied in 100-msec steps) and at optimal TI (mean value, 330 msec). Contrast-to-noise ratios (CNRs) of normal and infarcted myocardium and the area of infarcted myocardium were determined. Magnitude-reconstructed IR turbo FLASH images were compared with magnitude-reconstructed and phase-sensitive IR true FISP images. Two-tailed unpaired sample Student t test was used to compare CNRs, and two-tailed paired-sample Student t test was used to compare area of infarction.
Results:
Mean CNR of images acquired with IR turbo FLASH and IR true FISP (phase-sensitive and magnitude-reconstructed images) at optimal TI (mean value, 330 msec) were 6.6, 6.2, and 6.1, respectively. For a TI of 200 msec, CNR values were -4.3, -4.0, and 7.2, respectively; for TI of 600 msec, CNR values were 3.1, 3.3, and 4.3, respectively. Area of infarcted myocardium was underestimated on magnitude-reconstruction images (P = .002-.03) for short TI values (ie, 200 msec) for both sequences and for a TI of 300 msec for IR true FISP but not on phase-sensitive reconstructed IR true FISP images when compared with IR turbo FLASH images obtained at optimal TI.
Conclusion:
Phase-sensitive image reconstruction results in reduced need for precise choice of TI and more consistent image quality.
Insights
Phase-sensitive inversion-recovery (IR) magnetic resonance (MR) imaging improves myocardial infarction detection by reducing the need for precise inversion time (TI) selection. This method offers more consistent image quality for infarct imaging.
Area of Science:
- Cardiovascular Imaging
- Medical Physics
- Radiology
Background:
- Myocardial infarction (MI) diagnosis relies on accurate imaging of infarcted vs. normal myocardium.
- Traditional inversion-recovery (IR) magnetic resonance (MR) imaging requires precise inversion time (TI) selection for optimal contrast.
- Finding the exact TI to null normal myocardium signal can be challenging and time-consuming.
Purpose of the Study:
- To prospectively evaluate if phase-sensitive IR MR imaging eliminates the need for precise TI optimization.
- To assess if phase-sensitive reconstruction enhances contrast between infarcted and normal myocardium.
- To determine if this technique improves consistency in infarct imaging.
Main Methods:
- Prospective study of 20 patients with recent Q-wave MI using a 1.5-T MR system.
- Gadobenate dimeglumine contrast administration followed by imaging.
- Acquisition of images using segmented 2D IR turbo FLASH and IR true FISP sequences at various TIs and optimal TI.
- Comparison of contrast-to-noise ratios (CNRs) and infarct area between magnitude-reconstructed and phase-sensitive reconstructed images.
Main Results:
- Phase-sensitive IR true FISP images showed improved CNR at specific TI values compared to magnitude-reconstructed images.
- Infarcted myocardium area was underestimated on magnitude-reconstruction images at shorter TI values.
- Phase-sensitive reconstruction provided more accurate infarct area assessment, comparable to optimal TI IR turbo FLASH.
Conclusions:
- Phase-sensitive image reconstruction significantly reduces the need for precise TI selection in IR MR imaging.
- This technique leads to more consistent image quality and accurate assessment of myocardial infarction.
- Phase-sensitive reconstruction is a valuable advancement for cardiac MRI in MI patients.
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