Eleanor S K Berry1, Peter Jezzard1, Thomas W Okell1. 1. Centre for Functional Magnetic Resonance Imaging of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
Abstract
PURPOSE: Vessel-encoded pseudocontinuous arterial spin labeling allows the acquisition of vessel-selective angiograms and vascular territory perfusion maps. The technique generates a periodic variation in inversion efficiency across space that can be manipulated to encode specific combinations of vessels. Currently, the choice of these encodings is limited to scenarios with few vessels and may not optimize the signal-to-noise ratio (SNR). Here we present an automated, rapid method for calculating a minimal number of SNR optimal encodings for any number and arrangement of vessels. THEORY AND METHODS: The proposed optimized encoding scheme (OES) is a Fourier-based method that finds SNR optimized encodings to best match the ideal encodings for a set of vessels. For nine or fewer vessels, the calculation takes less than 3 s. RESULTS: In simulations, the OES method produces encodings for a range of vessel geometries that, on average, have an SNR efficiency 37% greater than that for random encoding. When labeling vessels in the neck in healthy subjects, the OES encodings result in images with higher SNR than other encoding methods. CONCLUSION: The OES results in a minimal number of encodings with a higher SNR efficiency than other encoding methods, regardless of the number or geometry of the vessels.
PURPOSE: Vessel-encoded pseudocontinuous arterial spin labeling allows the acquisition of vessel-selective angiograms and vascular territory perfusion maps. The technique generates a periodic variation in inversion efficiency across space that can be manipulated to encode specific combinations of vessels. Currently, the choice of these encodings is limited to scenarios with few vessels and may not optimize the signal-to-noise ratio (SNR). Here we present an automated, rapid method for calculating a minimal number of SNR optimal encodings for any number and arrangement of vessels. THEORY AND METHODS: The proposed optimized encoding scheme (OES) is a Fourier-based method that finds SNR optimized encodings to best match the ideal encodings for a set of vessels. For nine or fewer vessels, the calculation takes less than 3 s. RESULTS: In simulations, the OES method produces encodings for a range of vessel geometries that, on average, have an SNR efficiency 37% greater than that for random encoding. When labeling vessels in the neck in healthy subjects, the OES encodings result in images with higher SNR than other encoding methods. CONCLUSION: The OES results in a minimal number of encodings with a higher SNR efficiency than other encoding methods, regardless of the number or geometry of the vessels.
Authors: Wilby Williamson; Adam J Lewandowski; Nils D Forkert; Ludovica Griffanti; Thomas W Okell; Jill Betts; Henry Boardman; Timo Siepmann; David McKean; Odaro Huckstep; Jane M Francis; Stefan Neubauer; Renzo Phellan; Mark Jenkinson; Aiden Doherty; Helen Dawes; Eleni Frangou; Christina Malamateniou; Charlie Foster; Paul Leeson Journal: JAMA Date: 2018-08-21 Impact factor: 56.272
Authors: Daniel F Arteaga; Megan K Strother; L Taylor Davis; Matthew R Fusco; Carlos C Faraco; Brent A Roach; Allison O Scott; Manus J Donahue Journal: J Cereb Blood Flow Metab Date: 2016-01-01 Impact factor: 6.200
Authors: Luis Hernandez-Garcia; Verónica Aramendía-Vidaurreta; Divya S Bolar; Weiying Dai; Maria A Fernández-Seara; Jia Guo; Ananth J Madhuranthakam; Henk Mutsaerts; Jan Petr; Qin Qin; Jonas Schollenberger; Yuriko Suzuki; Manuel Taso; David L Thomas; Matthias J P van Osch; Joseph Woods; Moss Y Zhao; Lirong Yan; Ze Wang; Li Zhao; Thomas W Okell Journal: Magn Reson Med Date: 2022-08-19 Impact factor: 3.737
Authors: Thomas W Okell; Meritxell Garcia; Michael A Chappell; James V Byrne; Peter Jezzard Journal: Magn Reson Med Date: 2018-10-25 Impact factor: 4.668