title: Markerless attenuation correction for carotid MRI surface receiver coils in combined PET/MR imaging.
abstract: The purpose of the study was to evaluate the effect of attenuation of MR coils on quantitative carotid PET/MR exams. Additionally, an automated attenuation correction method for flexible carotid MR coils was developed and evaluated. The attenuation of the carotid coil was measured by imaging a uniform water phantom injected with 37 MBq of 18F-FDG in a combined PET/MR scanner for 24 min with and without the coil. In the same session, an ultra-short echo time (UTE) image of the coil on top of the phantom was acquired. Using a combination of rigid and non-rigid registration, a CT-based attenuation map was registered to the UTE image of the coil for attenuation and scatter correction. After phantom validation, the effect of the carotid coil attenuation and the attenuation correction method were evaluated in five subjects. Phantom studies indicated that the overall loss of PET counts due to the coil was 6.3% with local region-of-interest (ROI) errors reaching up to 18.8%. Our registration method to correct for attenuation from the coil decreased the global error and local error (ROI) to 0.8% and 3.8%, respectively. The proposed registration method accurately captured the location and shape of the coil with a maximum spatial error of 2.6 mm. Quantitative analysis in human studies correlated with the phantom findings, but was dependent on the size of the ROI used in the analysis. MR coils result in significant error in PET quantification and thus attenuation correction is needed. The proposed strategy provides an operator-free method for attenuation and scatter correction for a flexible MRI carotid surface coil for routine clinical use.
authors.affiliation: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Department of Biomedical Engineering, The City College of New York, New York, NY 10031, USA.
authors.forename: Mootaz
authors.initials: M
authors.lastname: Eldib
authors.forename: Jason
authors.initials: J
authors.lastname: Bini
authors.forename: Philip M
authors.initials: PM
authors.lastname: Robson
authors.forename: Claudia
authors.initials: C
authors.lastname: Calcagno
authors.forename: David D
authors.initials: DD
authors.lastname: Faul
authors.forename: Charalampos
authors.initials: C
authors.lastname: Tsoumpas
authors.forename: Zahi A
authors.initials: ZA
authors.lastname: Fayad
mesh_terms: D016477:Artifacts; D002340:Carotid Artery Diseases / Q000175:diagnosis*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008297:Male; D056888:Patient Positioning; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012984:Software; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18