Fast SE MRI of the chest: parameter optimization and comparison with conventional SE imaging
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E M Olson1, C J Bergin, M A King
1Department of Radiology, UCSDMC Thornton Hospital, La Jolla.
Objective:
This study was performed to optimize scanning parameters for fast spin echo (FSE) T2-weighted scans of the chest and to compare FSE T2-weighted images with conventional spin echo (CSE) T2-weighted scans.
Materials And Methods:
Thirty-nine FSE T2-weighted scans of the chest were obtained in 12 subjects to determine the effect of cardiac gating (with gating n = 20; without gating n = 19) and combinations of number of excitations (NEX) (2,4,8,16) and echo train length (ETL) (2,4,8,16) on scan quality and visibility of thoracic structures. An additional 15 chest MR examinations consisting of FSE T2- and CSE T1-, proton-density- (PD), and T2-weighted scans were obtained in 15 patients with a variety of thoracic abnormalities. The FSE T2-weighted scans were compared with CSE T2-weighted scans, and the combination of CSE T1- and FSE T2-weighted scans was compared with the combination of CSE PD- and T2-weighted scans.
Results:
Little difference in image quality was found between cardiac-gated and nongated FSE scans. Increasing the ETL resulted in increased motion artifact. Forty lesions were detected with FSE and 42 lesions with CSE T2-weighted scans. Fifty-three lesions were detected with the combination of CSE T1- and FSE T2-weighted sequences, whereas 44 lesions were detected with the combination of CSE PD- and T2-weighted scans.
Conclusions:
The combination of cardiac-gated CSE T1- and non-cardiac-gated FSE T2-weighted scans was 20% more sensitive and twice as fast as the combination of cardiac-gated CSE PD- and T2-weighted scans.