Phase-sensitive inversion recovery single-shot balanced steady-state free precession for detection of myocardial infarction during a single breathhold.

RATIONALE AND OBJECTIVES: We sought to show that phase-sensitive detection and a single-shot technique allow imaging of the heart for detection of myocardial infarction during a single breathhold without adaptation of the inversion time. MATERIALS AND METHODS: Thirty-five patients at 2 weeks to 3 months after Q-wave myocardial infarction were examined on a 1.5-T MR system 10 minutes after the administration of a double-dose extravascular contrast agent. In order to determine the optimal inversion recovery time (TI), a TI scout sequence was performed. An IR-turboFlash sequence with optimized TI was used as standard of reference. A phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence, which allows imaging of nine slices during one breathhold (TR/TE/FA/BW: 2.2 ms/1.1 ms/60 degrees , 8 degrees /1220 Hz/Px) was used with a nominal TI of 200 ms. Spatial resolution was identical for both techniques: 1.3 mm x 1.8 mm x 8 mm. Infarct volumes, area of infarction on a selected slice, and scan time for imaging delayed contrast enhancement (DCE) were compared. RESULTS: The mean values for the time of imaging DCE were 10 minutes 43 seconds for the IR turboFLASH and 17 seconds (P<.001) for the PSIR single-shot TrueFISP sequence. No significant difference was found for the mean values of the infarct volumes with 18.7 ml (IR turboFLASH) and 17.3 ml (PSIR single-shot TrueFISP). The values for the correlation coefficients of the infarct volumes and infarct areas of the two different techniques were r=0.95 (P<.004) and r=0.97 (P<.002). The regression equations were y=0.76+0.92*x and y=0.07+0.93*x, respectively. CONCLUSIONS: PSIR single-shot TrueFISP allows for accurate identification of myocardial infarction during a single breathhold with reduction of scan time by a factor of 38.

Single-shot inversion recovery TrueFISP for assessment of myocardial infarction.

OBJECTIVE: The aim of the study was to assess the diagnostic accuracy of imaging the myocardium with a fast multislice inversion recovery 2D single-shot true fast imaging with steady-state precession (trueFISP) sequence during a single breath-hold in comparison with an established segmented inversion recovery turbo fast low-angle shot (turboFLASH) sequence. SUBJECTS AND METHODS: Forty-three patients with myocardial infarction were examined on a 1.5-T MR system 10 min after administration of contrast material (gadodiamide, 0.2 mmol/kg) with a single-shot 2D multislice technique (single-shot inversion recovery trueFISP) that allows one to image the entire short axis during one breath-hold (18 heartbeats) and with a segmented 2D single-slice technique (inversion recovery turboFLASH) that requires one breath-hold per slice (12 heartbeats). Signal intensity was determined in normal myocardium, in infarcted myocardium, and in the left ventricle. The contrast-to-noise ratio (CNR) of normal and infarcted myocardium was determined. The areas of hyperintense infarctions on selected slices and the entire volumes were compared for both sequence techniques. RESULTS: The inversion recovery trueFISP sequence has a lower CNR than the inversion recovery turboFLASH sequence (mean values, 10.0 vs 12.9, respectively; p = 0.005) for differentiation of viable from nonviable myocardium. The CNR of injured myocardium and blood in the left ventricular cavity also has a lower value for the multislice technique compared with the single-slice technique (0.6 vs 1.2, respectively; p = 0.045). Assessment of the area of infarction within one slice (r = 0.97, p < 0.002) and of the volume of the entire infarction (r = 0.96, p < 0.003) is possible with excellent correlation of both techniques. CONCLUSION: Despite having a lower CNR, the inversion recovery 2D single-shot trueFISP sequence allows fast and accurate identification of the area and volume of infarction with high spatial resolution within a single breath-hold.

Phase-sensitive inversion-recovery MR imaging in the detection of myocardial infarction.

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.