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Continuous prospectively navigated multi‐echo GRE for improved BOLD imaging of the kidneys
Author(s) -
Morrell Glen Robert,
Jeong EunKee,
Shi Xianfeng,
Zhang Lei,
Lee Vivian ShuChing
Publication year - 2019
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.4078
Subject(s) - blood oxygen level dependent , nuclear medicine , breathing , kidney disease , kidney , medicine , magnetic resonance imaging , chemistry , radiology , anatomy
The objective of this study is to develop improved methods for renal blood oxygenation level dependent (BOLD) imaging. T2* mapping of the kidneys, or renal BOLD imaging, may depict renal oxygen levels and may be valuable as a noninvasive means of following the progression of renal disease. Current renal BOLD data is limited by imaging in a single breath hold, which results in low resolution and low signal‐to‐noise ratio (SNR). We compare a new free‐breathing renal BOLD method with conventional breath‐hold BOLD (BH‐BOLD). A multi‐echo GRE sequence with continuous prospective respiratory navigation and real‐time feedback was developed that allows high resolution and high SNR renal BOLD imaging with constant sequence repetition time (TR) during free‐breathing BOLD (FB‐BOLD). The sequence was evaluated in 10 normal volunteers and compared with conventional BH‐BOLD. Scan time for the FB‐BOLD sequence was approximately three minutes, compared with 15 seconds for the BH‐BOLD sequence. SNR of source images and residual error of T2* fitting were compared between the two methods. The FB‐BOLD sequence produced motion‐free T2* maps of the kidneys with SNR 1.9 times higher than BH‐BOLD images. Residual error of T2* fitting was consistently lower in the right kidney with FB‐BOLD (30% less than BH‐BOLD) but higher in the left kidney (80% more than BH‐BOLD), likely related to placement of the navigator on the right hemidiaphragm. A free‐breathing prospectively navigated renal BOLD sequence allows flexible tradeoff between scan time, resolution, and SNR.