title: A 31-channel MR brain array coil compatible with positron emission tomography.
abstract: OBJECTIVE
  Simultaneous acquisition of MR and positron emission tomography (PET) images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity.
  
  
  METHODS
  A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (signal to noise ratio [SNR], g-factor) and PET attenuation.
  
  
  RESULTS
  The coil design showed an improvement in attenuation by 190% (average) compared with conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical region of interest) compared with a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array.
  
  
  CONCLUSIONS
  The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.|Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors.forename: Christin Y
authors.initials: CY
authors.lastname: Sander
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
authors.forename: Boris
authors.initials: B
authors.lastname: Keil
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Chonde
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.|Health Sciences and Technology, Harvard MIT, Cambridge, Massachusetts, USA.|Department of Meridian & Acupuncture, Collaborating Center for Traditional Medicine, East-West Medical Research Institute and School of Korean Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Rosen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
authors.forename: Ciprian
authors.initials: C
authors.lastname: Catana
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.|Health Sciences and Technology, Harvard MIT, Cambridge, Massachusetts, USA.
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Wald
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D064847:Multimodal Imaging / Q000295:instrumentation*; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D012680:Sensitivity and Specificity
keywords: PET-optimized coil; RF coil attenuation; integrated PET/MR; multichannel brain array; simultaneous PET/MR