title: Accelerating MR Imaging Liver Steatosis Measurement Using Combined Compressed Sensing and Parallel Imaging: A Quantitative Evaluation.
abstract: OBJECTIVE
  To determine the limits of agreement of hepatic fat fraction and R2* relaxation rate quantified with accelerated magnetic resonance (MR) imaging reconstructed with combined compressed sensing and parallel imaging compared with conventional fully sampled acquisitions.
  
  
  METHODS
  Eleven subjects with type 2 diabetes and a healthy control subject were recruited with the approval of the Newcastle and North Tyneside 2 ethics committee and written consent. Undersampled data at ratios of 2.6×, 2.9×, 3.8×, and 4.8× were prospectively acquired in addition to fully sampled data by using five gradient echoes per repetition time at 3.0 T. Fat fraction maps were calculated by using combined compressed sensing and parallel imaging (CS-PI) reconstruction and Bland-Altman analysis performed to assess bias and 95% limits of agreement. Inter- and intrarater analysis was performed for quantitative fat fraction and R2* relaxation rate, and image quality was assessed with a four-point scale by two independent observers.
  
  
  RESULTS
  The fat fractions from the accelerated acquisitions had 95% limits of agreement of 1.2%, 1.2%, 1.1%, and 1.5%, respectively, with no bias. When compared with the intra- and interrater 95% limits of agreement (0.7% and 0.8%), acceleration of up to 3.8× did not greatly degrade the fat fraction measurements. No or minimal artifact was detected at 2.6× and 2.9× accelerations, moderate artifact was detected at 3.8× acceleration, and substantial artifact was detected at 4.8× acceleration.
  
  
  CONCLUSIONS
  Prospective undersampling and CS-PI reconstruction of liver fat fractions can be used to accelerate liver fat fraction measurements. The fat fractions and image quality produced were acceptable up to a factor of 3.8×, thereby shortening the required breath-hold duration from 17.7 seconds to 4.7 seconds.
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Louis W
authors.initials: LW
authors.lastname: Mann
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: David M
authors.initials: DM
authors.lastname: Higgins
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Carl N
authors.initials: CN
authors.lastname: Peters
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Sophie
authors.initials: S
authors.lastname: Cassidy
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Hodson
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Anna
authors.initials: A
authors.lastname: Coombs
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Roy
authors.initials: R
authors.lastname: Taylor
authors.affiliation: From the Newcastle Magnetic Resonance Centre (L.W.M., C.N.P., K.K.H., A.C., R.T., K.G.H.) and MoveLab (S.C.), Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE4 5PL, England; and Philips Healthcare, Guildford, England (D.M.H.).
authors.forename: Kieren G
authors.initials: KG
authors.lastname: Hollingsworth
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D044962:Data Compression / Q000379:methods*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D005234:Fatty Liver / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged