1. 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

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

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

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

6. 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…

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

8. 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

9. 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):
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

10. 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

11. 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

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

13. 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

14. Dynamic studies for quantification: 3D reconstructions1
Dynamic Acquisition 2
Dynamic
Reconstruction
Input function 3
Parametric Image
Kinetic Model

15. Dynamic studies for quantification: 4D reconstruction1
Dynamic Acquisition
Input function 2
Parametric Image
Kinetic Model

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

17. 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:

18. 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):
Marti, Falcon, et al (2013) Medical Physics, 40(9):

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

20. 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:

21. 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)