PURPOSE: To demonstrate that fluid and white matter suppression (FLAWS) imaging can be used for high-resolution T1 mapping with low transmitted bias field ( B 1 + ) sensitivity at 7T. METHODS: The FLAWS sequence was optimized for 0.8-mm isotropic resolution imaging. The theoretical accuracy and precision of the FLAWS T1 mapping was compared with the one of the magnetization-prepared two rapid gradient echoes (MP2RAGE) sequence optimized for low B 1 + sensitivity. FLAWS images were acquired at 7T on six healthy volunteers (21 to 48 years old; two women). MP2RAGE and saturation-prepared with two rapid gradient echoes (SA2RAGE) datasets were also acquired to obtain T1 mapping references and B 1 + maps. The contrast-to-noise ratio (CNR) between brain tissues was measured in the FLAWS-hco and MP2RAGE-uni images. The Pearson correlation was measured between the MP2RAGE and FLAWS T1 maps. The effect of B 1 + on FLAWS T1 mapping was assessed using the Pearson correlation. RESULTS: The FLAWS-hco images were characterized by a higher brain tissue CNR ( CNR WM / GM = 5.5 , CNR WM / CSF = 14.7 , CNR GM / CSF = 10.3 ) than the MP2RAGE-uni images ( CNR WM / GM = 4.9 , CNR WM / CSF = 6.6 , CNR GM / CSF = 3.7 ). The theoretical accuracy and precision of the FLAWS T1 mapping ( acc = 91.9 % ; prec = 90.2 % ) were in agreement with those provided by the MP2RAGE T1 mapping ( acc = 90.0 % ; prec = 86.8 % ). A good agreement was found between in vivo T1 values measured with the MP2RAGE and FLAWS sequences (r = 0.91). A weak correlation was found between the FLAWS T1 map and the B 1 + map within cortical gray matter and white matter segmentations ( r WM = - 0.026 ; r GM = 0.081 ). CONCLUSION: The results from this study suggest that FLAWS is a good candidate for high-resolution T1 -weighted imaging and T1 mapping at the field strength of 7T.
PURPOSE: To demonstrate that fluid and white matter suppression (FLAWS) imaging can be used for high-resolution T1 mapping with low transmitted bias field ( B 1 + ) sensitivity at 7T. METHODS: The FLAWS sequence was optimized for 0.8-mm isotropic resolution imaging. The theoretical accuracy and precision of the FLAWS T1 mapping was compared with the one of the magnetization-prepared two rapid gradient echoes (MP2RAGE) sequence optimized for low B 1 + sensitivity. FLAWS images were acquired at 7T on six healthy volunteers (21 to 48 years old; two women). MP2RAGE and saturation-prepared with two rapid gradient echoes (SA2RAGE) datasets were also acquired to obtain T1 mapping references and B 1 + maps. The contrast-to-noise ratio (CNR) between brain tissues was measured in the FLAWS-hco and MP2RAGE-uni images. The Pearson correlation was measured between the MP2RAGE and FLAWS T1 maps. The effect of B 1 + on FLAWS T1 mapping was assessed using the Pearson correlation. RESULTS: The FLAWS-hco images were characterized by a higher brain tissue CNR ( CNR WM / GM = 5.5 , CNR WM / CSF = 14.7 , CNR GM / CSF = 10.3 ) than the MP2RAGE-uni images ( CNR WM / GM = 4.9 , CNR WM / CSF = 6.6 , CNR GM / CSF = 3.7 ). The theoretical accuracy and precision of the FLAWS T1 mapping ( acc = 91.9 % ; prec = 90.2 % ) were in agreement with those provided by the MP2RAGE T1 mapping ( acc = 90.0 % ; prec = 86.8 % ). A good agreement was found between in vivo T1 values measured with the MP2RAGE and FLAWS sequences (r = 0.91). A weak correlation was found between the FLAWS T1 map and the B 1 + map within cortical gray matter and white matter segmentations ( r WM = - 0.026 ; r GM = 0.081 ). CONCLUSION: The results from this study suggest that FLAWS is a good candidate for high-resolution T1 -weighted imaging and T1 mapping at the field strength of 7T.
Authors: Ya-Jun Ma; Dina Moazamian; Daniel M Cornfeld; Paul Condron; Samantha J Holdsworth; Mark Bydder; Jiang Du; Graeme M Bydder Journal: Quant Imaging Med Surg Date: 2022-09