title: Accelerated echo-planar J-resolved spectroscopic imaging in the human brain using compressed sensing: a pilot validation in obstructive sleep apnea.
abstract: OBJECTIVE
  Echo-planar J-resolved spectroscopic imaging is a fast spectroscopic technique to record the biochemical information in multiple regions of the brain, but for clinical applications, time is still a constraint. Investigations of neural injury in obstructive sleep apnea have revealed structural changes in the brain, but determining the neurochemical changes requires more detailed measurements across multiple brain regions, demonstrating a need for faster echo-planar J-resolved spectroscopic imaging. Hence, we have extended the compressed sensing reconstruction of prospectively undersampled 4D echo-planar J-resolved spectroscopic imaging to investigate metabolic changes in multiple brain locations of patients with obstructive sleep apnea and healthy controls.
  
  
  METHODS
  Nonuniform undersampling was imposed along 1 spatial and 1 spectral dimension of 4D echo-planar J-resolved spectroscopic imaging, and test-retest reliability of the compressed sensing reconstruction of the nonuniform undersampling data was tested by using a brain phantom. In addition, 9 patients with obstructive sleep apnea and 11 healthy controls were investigated by using a 3T MR imaging/MR spectroscopy scanner.
  
  
  RESULTS
  Significantly reduced metabolite differences were observed between patients with obstructive sleep apnea and healthy controls in multiple brain regions: NAA/Cr in the left hippocampus; total Cho/Cr and Glx/Cr in the right hippocampus; total NAA/Cr, taurine/Cr, scyllo-Inositol/Cr, phosphocholine/Cr, and total Cho/Cr in the occipital gray matter; total NAA/Cr and NAA/Cr in the medial frontal white matter; and taurine/Cr and total Cho/Cr in the left frontal white matter regions.
  
  
  CONCLUSIONS
  The 4D echo-planar J-resolved spectroscopic imaging technique using the nonuniform undersampling-based acquisition and compressed sensing reconstruction in patients with obstructive sleep apnea and healthy brain is feasible in a clinically suitable time. In addition to brain metabolite changes previously reported by 1D MR spectroscopy, our results show changes of additional metabolites in patients with obstructive sleep apnea compared with healthy controls.
authors: From the Departments of Radiological Sciences (M.K.S., R.N., R.K., J.P.V., J.F., M.A.T.).
authors: M K
authors: MK
authors: Sarma
authors: From the Departments of Radiological Sciences (M.K.S., R.N., R.K., J.P.V., J.F., M.A.T.).
authors: R
authors: R
authors: Nagarajan
authors: School of Nursing (P.M.M.), University of California, Los Angeles, Los Angeles, California.
authors: P M
authors: PM
authors: Macey
authors: From the Departments of Radiological Sciences (M.K.S., R.N., R.K., J.P.V., J.F., M.A.T.)Anesthesiology (R.K.), David Geffen School of Medicine.
authors: R
authors: R
authors: Kumar
authors: From the Departments of Radiological Sciences (M.K.S., R.N., R.K., J.P.V., J.F., M.A.T.).
authors: J P
authors: JP
authors: Villablanca
authors: From the Departments of Radiological Sciences (M.K.S., R.N., R.K., J.P.V., J.F., M.A.T.).
authors: J
authors: J
authors: Furuyama
authors: From the Departments of Radiological Sciences (M.K.S., R.N., R.K., J.P.V., J.F., M.A.T.) athomas@mednet.ucla.edu.
authors: M A
authors: MA
authors: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D001927:Brain Diseases / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism; D044962:Data Compression; D017352:Echo-Planar Imaging / Q000379:methods* / Q000592:standards*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008875:Middle Aged; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D010865:Pilot Projects; D015203:Reproducibility of Results; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000175:diagnosis / Q000378:metabolism