Application of single shot free-breathing fast imaging employing steady state sequence in cardiac magnetic resonance imaging

OBJECTIVE

To investigate the imaging quality of single shot (SS) fast imaging employing steady state (FIESTA) sequence in contrast-enhanced cardiac magnetic resonance (MR) examination, in comparison with the segmented inversion recovery 2D fast gradient echo (IR FGRE) sequence.

MATERIALS AND METHODS

Fifty-two cases with suspected or known heart disease were enrolled in this study, including 24 patients who had enhanced myocardium in myocardial delayed enhancement (MDE). We analyzed the imaging quality of the sequences by measuring the myocardium and blood pool signal-to-noise ratios (SNR) and the contrast-to-noise ratios (CNR) of blood pool relative to normal myocardium and of enhanced myocardium relative to normal myocardium and compared the new sequences with traditional sequence.

RESULTS

The scanning time of SS FIESTA was significantly shortened as compared to IR FGRE. The differences in the image quality scores, enhanced myocardium (EM) mass and percentages, SNR(bp), SNR(myo), CNR(myo/bp) and CNR(l/bg) were not statistically significant between SS FIESTA and IR FGRE (P > 0.05). However, the difference in CNR(em/myo) was statistically significant between SS FIESTA and IR FGRE (P < 0.0001), with CNR(em/myo) of IR FGRE higher than SS FIESTA.

CONCLUSION

Single shot FIESTA speeded up the acquisition time, halving it to (27.6 ± 1.8 s) instead of 146 + 13.8 s (IR FGRE), it had higher SNR and CNR, and its image quality did not differ significantly from IR FGRE. The SS FIESTA is more suitable for patients with severely heart diseases or those unable to hold breath. 3D IR FGRE sequence had higher SNR(myo) than the others and it is suitable for displaying the subendocardial scar. However, it has more artefacts and poor imaging quality than IR FGRE.

Inversion recovery single-shot TurboFLASH for assessment of myocardial infarction at 3 Tesla

PURPOSE

The aim of the study was to assess the diagnostic accuracy of imaging myocardial infarction with a single-shot inversion recovery turbofast low-angle shot (SS IR turboFLASH) sequence at 3.0 Tesla in comparison with an established segmented inversion recovery turboFLASH sequence at 1.5 Tesla.

MATERIALS AND METHODS

Fifteen patients with myocardial infarction were examined at a 1.5 Tesla magnetic resonance (MR) System (Avanto, Siemens, Medical Solutions) and at a 3.0 Tesla MR system (TIM Trio, Siemens, Medical Solutions). Imaging delayed enhancement was started 15 minutes after application of contrast material. A SS IR turboFLASH was performed at 3.0 Tesla and compared with a segmented IR turboFLASH sequence at 1.5 and at 3.0 Tesla. The IR turboFLASH sequence at 1.5 Tesla served as reference method. Infarct volumes, contrast/noise ratio (CNR) of infarcted and normal myocardium were compared with the reference method.

RESULTS

The Single-Shot IR turboFLASH technique allows imaging 9 slices during a single breath-hold. The CNR between infarction and normal myocardium of the reference method was 6.4 at 1.5 Tesla. The mean value of CNR of the IR turboFLASH sequence was 7.3 at 3.0 Tesla for the single-shot technique and 14.1 at 3.0 Tesla for the segmented technique. No significant difference was found for the CNR values of the reference technique at 1.5 Tesla and the single-shot technique at 3.0 Tesla, however for the comparison of the segmented technique at 1.5 and at 3 Tesla (P = 0.0001). The correlation coefficients of the infarct volumes, determined with the Single-Shot IR turboFLASH and the segmented IR turboFLASH technique at 3.0 compared with the reference method, were r = 0.95 (P < 0.0001) and r = 0.95 (P < 0.0001).

CONCLUSION

The loss of CNR, which is caused by replacement of the segmented technique by the single-shot technique, is completely compensated by the approximately 2-fold CNR increase at the higher field strength. The IR turboFLASH technique at 3.0 Tesla IR can be used as a single-shot technique with acquisition of 9 slices during a single breath-hold without loss of diagnostic accuracy compared with the segmented technique at 1.5 Tesla.

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 (PSIR) Single-Shot TrueFISP for Assessment of Myocardial Infarction at 3 Tesla

PURPOSE

The aim of the current study was to show if contrast-to-noise ratio (CNR) could be improved without loss of diagnostic accuracy if a phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence is used at 3.0 T instead of 1.5 T.

MATERIAL AND METHODS

Ten patients with myocardial infarction were examined on a 1.5 T magnetic resonance (MR) system (Avanto, Siemens Medical Systems) and at a 3.0 T MR system. Imaging delayed contrast enhancement was started 10 minutes after application of contrast material. A phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence was used at 1.5 and 3.0 T and compared with a segmented IR turboFLASH sequence at 1.5 T, which served as the reference method. Infarct volumes and CNR of infarction and normal myocardium were compared with the reference method.

RESULTS

The PSIR Single-Shot TrueFISP technique allows for imaging nine slices during a single breathhold without adaptation of the inversion time. The mean value of CNR between infarction and normal myocardium was 5.9 at 1.5 T and 12.2 at 3.0 T (magnitude images). The CNR mean value of the reference method was 8.4. The CNR mean value at 3.0 T was significantly (P = 0.03) higher than the mean value of the reference method. The correlation coefficients of the infarct volumes, determined with the PSIR single-shot TrueFISP technique at 1.5 T and at 3.0 T and compared with the reference method, were r = 0.96 (P = 0.001) and r = 0.99 (P = 0.0001).

CONCLUSION

The use of PSIR single-shot TrueFISP at 3.0 T allows for accurate detection and assessment of myocardial infarction. CNR is significantly higher at 3.0 T compared with 1.5 T. The PSIR single-shot technique at 3.0 T provides a higher CNR than the segmented reference technique at 1.5 T.