Software for Tomographic Image Reconstruction Radionuclide Imaging: Lecture 1 29/1/2013 School of Medicine FACULTY OF MEDICINE AND HEALTH Software for Tomographic Image Reconstruction Charalampos Tsoumpas, PhD Division of Medical Physics Leeds Institute of Genetics, Health and Therapeutics C.Tsoumpas@leeds.ac.uk

Aim State of the art reconstruction software Trigger fruitful discussions on how to plan the future for PET reconstruction

“Fathers” of Image Reconstruction (1917 to 1970) Johan Radon Allan M. Cormack Godfrey Hounsfield Nobel Prize in Medicine & Physiology (1979)

“Fathers” of PET Image Reconstruction (1982 to 1994) Shepp & Vardi: MLEM, IEEE TMI, 1982 Hudson & Larkin: OSEM, IEEE TMI 1994

Reconstruction Directions: Mathematical / Computational Modelling: Objective / Cost Function, Forward & Backward operation, Optimization algorithm / Statistical fit, Smoothness, Regularization, Joint emission & attenuation calculation, GPUs Physical Modelling: Attenuation & Scatter, Randoms, Detector Response, Positron Range Correction, Accolinearity, Bed motion… Physiological Modelling: Motion correction (Respiratory, Cardiac, Peristalsis, Bulk, …), Tracer kinetics, Stuctural-Functional Priors, Metabolites…

Mathematical Modelling: Q.Clear Regularized Reconstruction SUV: 3.2 SUV: 7.2 © 2014 General Electric Company

Physical Modelling: Point Spread Function (PSF) Spatial PSF (PSF) Point OSEM PSF+OSEM Point-Spread Improving PET With HD•PET Michael E. Casey, Ph.D, Director of Physics, Siemens Molecular Imaging White Paper Resolution degradation effects reduce the quantification and segmentation capabilities of PET images

Physical Modelling: Point Spread Function (PSF) Temporal PSF (Time of Flight - ToF) OSEM PSF+OSEM ToF+PSF+OSEM Townsend (2008) Dual-Modality Imaging: Combining Anatomy and Function J Nucl Med 49(6):938-955 Improving PET With HD•PET + ToF Michael E. Casey, Ph.D, Director of Physics, Siemens Molecular Imaging White Paper Spatial and temporal PSF can be modelled within reconstruction and help recover resolution, increase sensitivity and reduce noise

Physical Modelling: Positron Range Correction Simulated lung phantom no positron range correction Positron range correction Example with Ga-68 sources Bertolli et al (2014) PSMR abstracts

Physiological Modelling: Respiratory Motion Respiratory motion ≈ 6-18mm PET scanners spatial resolution ≈ 4-6mm Effects of respiratory motion blurring: Limitation of tumor detectability Underestimation of tracer uptake values Schleyer et al (2011) PMB Without motion With motion Without motion With motion SUV=6 SUV=9 Motion reduces spatial resolution and degrades image quality & quantification PET has increased diagnostic value with accurate motion correction

Regularized Motion Compensated Image Reconstruction (MCIR) MCIR-OSEM MCIR-OS-MRP-OSL Tsoumpas, Polycarpou, Thielemans, et al (2013) Phys Med Biol

Physiological Modelling: Parametric Reconstruction Introduction to Radionuclide Imaging 9/10/2013 Physiological Modelling: Parametric Reconstruction Kinetic Model (Parameters: K1, k2, k3, k4) CP CF k3 CB K1 k4 CT k2 CP: Plasma concentration CT: Total tissue concentration CB: Concentration of bound tracer CF: Concentration of free tracer

Dynamic studies for quantification: 3D reconstructions 1 Dynamic Acquisition 2 Dynamic Reconstruction Input function 3 Parametric Image Kinetic Model

Dynamic studies for quantification: 4D reconstruction 1 Dynamic Acquisition Input function 2 Parametric Image Kinetic Model

Parametric Reconstruction Example Truth FBP OSEM 4D OSEM Tsoumpas, et al (2008) Med Phys

Open Source reconstruction software Image Reconstruction Toolbox by Fessler: set of open source matlab routines for image reconstruction and processing. ASPIRE by Fessler. License allows non-commercial usage only. TIRIUS provides OSEM for PET reconstruction using a well-designed GUI. Could use algorithms in STIR 1.4 but not compatible with STIR 2 or later. Licence: GNU LGPL. NiftyRec: matlab (and some python) interface to C/GPU projectors and some reconstruction algorithms. Current projectors are mostly suitable for SPECT. License: BSD-style. EMrecon is another recently released package, using expectation maximisation; License unclear QSPECT is a recently released package for SPECT reconstruction using MLEM or OSEM. Troll: pyCuda-based toolkit for PET, SPECT, CT. Early development stage (2013). License: GPL3. PRESTO: a versatile C++ Library for fully 3D iterative PET reconstruction More Information: http://stir.sf.net

Software for tomographic image reconstruction PET & SPECT reconstruction Analytic & iterative 3D reconstruction algorithms: FBP-3DRP, SSRB, FORE, OSEM, OSMAPOSL (MRP), OSSPS (quadratic prior), list-mode Fast iterative reconstruction with parallel processing using MPI Attenuation & scatter correction, image/sinogram data manipulation, ROI parameters estimation, … Motion Compensated Image Reconstruction (within or post-reconstruction) Pharmacokinetic modelling classes for direct parametric reconstruction Thielemans, Tsoumpas, et al (2012) Physics in Medicine and Biology, 57(4):867-83. Marti, Falcon, et al (2013) Medical Physics, 40(9):092502.

Open Discussion: The translational research cycle Hardware & Radiotracers Software Clinical Application Industry Idea

2014 IEEE NSS-MIC STIR Users’ & Developers’ Meeting (2 hours + free dinner) Room 303, Seattle Conference Centre Date & Time: 6.30pm, Thursday, 13/11/2014 Organisers: Kris Thielemans & Harry Tsoumpas More Information: http://stir.sf.net

Introduction to Radionuclide Imaging 9/10/2013 School of Medicine FACULTY OF MEDICINE AND HEALTH Thanks to: Dr. Kris Thielemans (UCL) Dr. Irene Polycarpou (KCL) Miss Ottavia Bertolli (UCL) C.Tsoumpas@leeds.ac.uk