Doaa Felemban1,2, Rinus G Verdonschot3, Yuri Iwamoto1, Yuka Uchiyama1, Naoya Kakimoto3, Sven Kreiborg1,4, Shumei Murakami1,4. 1. 1 Department of Oral and Maxillofacial Radiology, Osaka University Graduate School of Dentistry , Osaka , Japan. 2. 2 Department of Oral and Maxillofacial Radiology, College of Dentistry, Taibah University , Medina , Saudi Arabia. 3. 3 Department of Oral and Maxillofacial Radiology, Institute of Biomedical & Health Sciences, Hiroshima University , Hiroshima , Japan. 4. 4 3D Craniofacial Image Research Laboratory, School of Dentistry, Copenhagen University Hospital Rigshospitalet, University of Copenhagen , Copenhagen , Denmark.
Abstract
OBJECTIVES: Our goal was to assess MR image uniformity by investigating aspects influencing said uniformity via a method laid out by the National Electrical Manufacturers Association (NEMA). METHODS: Six metallic materials embedded in a glass phantom were scanned (i.e. Au, Ag, Al, Au-Ag-Pd alloy, Ti and Co-Cr alloy) as well as a reference image. Sequences included spin echo (SE) and gradient echo (GRE) scanned in three planes (i.e. axial, coronal, and sagittal). Moreover, three surface coil types (i.e. head and neck, Brain, and temporomandibular joint coils) and two image correction methods (i.e. surface coil intensity correction or SCIC, phased array uniformity enhancement or PURE) were employed to evaluate their effectiveness on image uniformity. Image uniformity was assessed using the National Electrical Manufacturers Association peak-deviation non-uniformity method. RESULTS: Results showed that temporomandibular joint coils elicited the least uniform image and brain coils outperformed head and neck coils when metallic materials were present. Additionally, when metallic materials were present, spin echo outperformed gradient echo especially for Co-Cr (particularly in the axial plane). Furthermore, both SCIC and PURE improved image uniformity compared to uncorrected images, and SCIC slightly surpassed PURE when metallic metals were present. Lastly, Co-Cr elicited the least uniform image while other metallic materials generally showed similar patterns (i.e. no significant deviation from images without metallic metals). CONCLUSIONS: Overall, a quantitative understanding of the factors influencing MR image uniformity (e.g. coil type, imaging method, metal susceptibility, and post-hoc correction method) is advantageous to optimize image quality, assists clinical interpretation, and may result in improved medical and dental care.
OBJECTIVES: Our goal was to assess MR image uniformity by investigating aspects influencing said uniformity via a method laid out by the National Electrical Manufacturers Association (NEMA). METHODS: Six metallic materials embedded in a glass phantom were scanned (i.e. Au, Ag, Al, Au-Ag-Pd alloy, Ti and Co-Cr alloy) as well as a reference image. Sequences included spin echo (SE) and gradient echo (GRE) scanned in three planes (i.e. axial, coronal, and sagittal). Moreover, three surface coil types (i.e. head and neck, Brain, and temporomandibular joint coils) and two image correction methods (i.e. surface coil intensity correction or SCIC, phased array uniformity enhancement or PURE) were employed to evaluate their effectiveness on image uniformity. Image uniformity was assessed using the National Electrical Manufacturers Association peak-deviation non-uniformity method. RESULTS: Results showed that temporomandibular joint coils elicited the least uniform image and brain coils outperformed head and neck coils when metallic materials were present. Additionally, when metallic materials were present, spin echo outperformed gradient echo especially for Co-Cr (particularly in the axial plane). Furthermore, both SCIC and PURE improved image uniformity compared to uncorrected images, and SCIC slightly surpassed PURE when metallic metals were present. Lastly, Co-Cr elicited the least uniform image while other metallic materials generally showed similar patterns (i.e. no significant deviation from images without metallic metals). CONCLUSIONS: Overall, a quantitative understanding of the factors influencing MR image uniformity (e.g. coil type, imaging method, metal susceptibility, and post-hoc correction method) is advantageous to optimize image quality, assists clinical interpretation, and may result in improved medical and dental care.
Authors: Ayman F Hegab; Ahmed Hossni Youssef; Hossam I Abd Al Hameed; Khaled Said Karam Journal: Oral Surg Oral Med Oral Pathol Oral Radiol Date: 2017-10-12
Authors: H A Alsaffar; D P Goldstein; E V King; J R de Almeida; D H Brown; R W Gilbert; P J Gullane; O Espin-Garcia; W Xu; J C Irish Journal: J Otolaryngol Head Neck Surg Date: 2016-11-22