Abstract:
PURPOSE:To obtain whole-brain high-resolution T2 maps in 2 minutes by combining simultaneous multislice excitation and low-power PINS (power independent of number of slices) refocusing pulses with undersampling and a model-based reconstruction. METHODS:A multi-echo spin-echo sequence was modified to acquire multiple slices simultaneously, ensuring low specific absorption rate requirements. In addition, the acquisition was undersampled to achieve further acceleration. Data were reconstructed by subsequently applying parallel imaging to separate signals from different slices, and a model-based reconstruction to estimate quantitative T2 from the undersampled data. The signal model used is based on extended phase graph simulations that also account for nonideal slice profiles and B1 inhomogeneity. In vivo experiments with 3 healthy subjects were performed to compare accelerated T2 maps to fully sampled single-slice acquisitions. The accuracy of the T2 values was assessed with phantom experiments by comparing the T2 values to single-echo spin-echo measurements. RESULTS:In vivo results showed that conventional multi-echo spin-echo, simultaneous multislice, and undersampling result in similar mean T2 values within regions of interest. However, combining simultaneous multislice and undersampling results in higher SDs (about 7 ms) in comparison to a conventional sequence (about 3 ms). The T2 values were reproducible between scan and rescan (SD < 1.2 ms) within subjects and were in similar ranges across subjects (SD < 4.5 ms). CONCLUSION:The proposed method is a fast T2 mapping technique that enables whole-brain acquisitions at 0.7-mm in-plane resolution, 3-mm slice thickness, and low specific absorption rate in 2 minutes.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Hilbert T,Schulz J,Marques JP,Thiran JP,Krueger G,Norris DG,Kober Tdoi
10.1002/mrm.27890subject
Has Abstractpub_date
2019-12-01 00:00:00pages
2090-2103issue
6eissn
0740-3194issn
1522-2594journal_volume
82pub_type
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