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The challenge of bias‐free coil combination for quantitative susceptibility mapping at ultra‐high field
Author(s) -
Bollmann Steffen,
Robinson Simon Daniel,
O'Brien Kieran,
Vegh Viktor,
Janke Andrew,
Marstaller Lars,
Reutens David,
Barth Markus
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26644
Subject(s) - phase (matter) , electromagnetic coil , channel (broadcasting) , reference data , quantitative susceptibility mapping , sensitivity (control systems) , computer science , field (mathematics) , magnetic resonance imaging , physics , data mining , mathematics , electronic engineering , medicine , telecommunications , radiology , engineering , quantum mechanics , pure mathematics
Purpose Quantitative susceptibility mapping is a technique to estimate the magnetic property of tissue with particularly high sensitivity at ultra‐high field. However, a key challenge at ultra‐high field is the combination of phase data acquired using phased array receive coils. Several methods for combining phase data have been proposed, but the influence of coil combination choices on susceptibility quantitation has not been studied systematically. Methods We combined phase data using COMPOSER (COMbining Phase data using a Short Echo‐time Reference scan) and a reference‐free channel‐by‐channel method. We investigated the effect of the chosen combination method on susceptibility results in a group of 28 participants at 7 Tesla. Results Our results show that reference scans can bias susceptibility values. Although the proposed reference‐free channel‐by‐channel method cannot remove transmit field phase, it shows comparable results to the COMPOSER method in which a high‐resolution ultrashort echo‐time reference scan was used. Conclusions We conclude that ultrashort echo‐time reference scans reduce quantitation bias and remove the transmit field phase when using COMPOSER to combine phase data, and not combining the phase data before susceptibility processing avoids this bias, resulting in comparable results. Magn Reson Med 79:97–107, 2018. © 2017 InternationalSociety for Magnetic Resonance in Medicine.