2019 Accelerating Magnetic Resonance Imaging (MRI) using GPUs Presenter Dr.Hammad Omer Assistant Professor Group Lead: Medical Image Processing Research Group (MIPRG) (www.miprg.com) COMSATS University Islamabad (Pakistan) Thursday, March 21, 2019 1
Thursday, March 21, 2019 Outline ► Overview of Magnetic Resonance Imaging (MRI) ► GPU based Advance MR Image Reconstruction ● GPU based GRAPPA Reconstruction using CUDA ● GPU based SENSE Reconstruction using CUDA ● GPU based Gridding using CUDA ► Magnetic Resonance Finger Printing (MRF) ● GPU based MRF using CUDA ► Acknowledgements 2
Thursday, March 21, 2019 What is MRI ? Outline ► MIPRG at Glance ► Overview ● Safe and painless diagnostic procedure ► What is MRI? ● Excellent soft tissue contrast ► MRI Hardware ● No need to change the position of the ► How MRI works? patient ► MR Image Formation ● Non-invasive ► Limitations in conventional Human head MRI ● Diagnoses & monitors treatments such as (Coronal axis) ► Parallel MRI ► Heart problems Magnetic Resonance Finger printing Blockage or enlargement of blood ► Acknowledgements vessels Lungs Diseases of the liver such as cirrhosis Human head (sagittal axis) Tumors and other cancer related abnormalities 3
Thursday, March 21, 2019 MRI Hardware Outline ► MIPRG at Glance ► Overview ● Magnets ► What is MRI? Permanent Magnets ► MRI Hardware Resistive Magnets ► How MRI works? Super Conducting Magnets ► MR Image Formation ● RF Coils ► Limitations in conventional MRI Surface coils MAGNETOM Skyra 3T (Siemens ) ► Parallel MRI Body coils ► Magnetic Resonance Finger Head coils printing ► Acknowledgements ● Gradient Coils Induce non-linear change in the magnetic field 4
Thursday, March 21, 2019 How MRI works Outline ► MIPRG at Glance ► Overview RF-RX ► What is MRI? ► MRI Hardware ► How MRI works? ► MR Image Formation ► Limitations in conventional RF - TX MRI ► Parallel MRI Magnetic Filed ► Magnetic Resonance Finger printing ► Acknowledgements Fourier Transform Image NMR Signal 5
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 6
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 7
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 8
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 9
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 10
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 11
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 12
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 13
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MRI Pulse Sequence and Data Acquisition ► Overview ► What is MRI? Basic Gradient-Echo Pulse Sequence k -Space ► MRI Hardware + 𝒍 𝒛 ► How MRI works? ► MR Image Formation ► Limitations in conventional + 𝒍 𝐲 - 𝒍 𝒚 MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements - 𝒍 𝐳 𝒍 𝒛 = Phase encoding Direction 𝒍 𝒚 = Frequency encoding Direction 14
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● MR Pulse Sequence and Data Acquisition ► Overview ► The Total acquisition time ( 𝑈 What is MRI? 𝐵 ) (fully sampled k -space) ► MRI Hardware 𝑼 𝑩 = 𝑼 𝑺 × 𝑶 𝒛 ► How MRI works? Where, ► MR Image 𝑼 𝑺 = Time required to collect a single line of k -space Formation 𝑶 𝒛 = Total number of PE lines that must be acquired ► Limitations in conventional MRI ► Parallel MRI ► Magnetic Resonance Finger printing FFT ► Acknowledgements 15
Thursday, March 21, 2019 MR Image Formation Outline ► MIPRG at Glance ● Image Resolution and Contrast ► Overview ∆𝑦 ∆𝑙 𝑦 ► What is MRI? ∆𝑙 𝑧 ► ∆𝑧 MRI Hardware ► How MRI works? ► MR Image Fourier Transform Formation ► Limitations in conventional MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements 16
Friday, March 15, 2019 9 MR Image Formation Outline ► MIPRG at Glance ● k -space sampling trajectories ► Overview ► What is MRI? ► MRI Hardware ► How MRI works? ► MR Image Formation ► Limitations in conventional MRI ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements Thursday, March 21, 2019 17
Thursday, March 21, 2019 Limitations in Conventional MRI Outline ► MIPRG at Glance ● Major Limitations ► Overview ► What is MRI? Scan duration of conventional MRI (30 to 40 mins) ► MRI Hardware ► How MRI works? Too expensive (typically £350-£500 per hour) ► MR Image Formation ► Limitations in Long Breath hold (abdominal imaging) conventional MRI Moving structures (e.g. heart) ► Parallel MRI ► Magnetic Resonance Finger printing Contrast changes( Flowing blood ) ► Acknowledgements 18
Thursday, March 21, 2019 Parallel MRI Outline ► MPIRG at Glance ● Key properties of pMRI techniques ● Multichannel receiver coils ► Overview 1. Acceleration factors ● Reduce acquisition time ► Parallel MRI 2. Reconstruction accuracy ● Advanced pMRI Techniques ► Magnetic Resonance Finger 3. Reconstruction time printing (GRAPPA, SENSE etc.) ► Acknowledgements Parallel Imaging using multi-channel receiver coils Example of 4-channe receiver coil 19
Thursday, March 21, 2019 Parallel MRI Outline ► MPIRG at Glance ► Overview Image based reconstruction ► Parallel MRI ► Magnetic Resonance Finger printing ► Acknowledgements k -space based reconstruction 20
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