software and hardware advances in nuclear cardiology...2016/10/12 · software and hardware...
TRANSCRIPT
![Page 1: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/1.jpg)
Software and Hardware Advances in
Nuclear Cardiology
Department of Medical Physics, Westmead Hospital, Sydney
Faculty of Health Sciences, University of Sydney
Roger Fulton
![Page 2: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/2.jpg)
Software Advances :
Iterative Reconstruction Algorithms
![Page 3: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/3.jpg)
PatientOriginal projections
Estimated projectionsCurrent estimate
original estimate
update(x ratio)
FP
BP NOCHANGE
Maximum Likelihood Expectation Maximisation (MLEM)
![Page 4: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/4.jpg)
Iterative reconstruction algorithms can• model the imaging system and other factors
affecting the measured projections, such as• attenuation• noise• scatter• factors degrading spatial resolution • patient motion
4
![Page 5: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/5.jpg)
Modelling the system response for resolution recovery
Piccinelli M. et al. (2016) Cardiology Clinics, 34(1), 1.
5
![Page 6: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/6.jpg)
PatientOriginal projections
Estimated projectionsCurrent estimate
original estimate
update(x ratio)
FP
BP NOCHANGE
Maximum Likelihood Expectation Maximization (MLEM)
6
![Page 7: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/7.jpg)
Accelerating Iterative Reconstruction :
Ordered Subsets EM (OSEM)
![Page 8: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/8.jpg)
2 projections/subset8 subsets
4 projections/subset4 subsets
8 projections/subset2 subsets
‘Ordered Subsets’ reconstruction
Acceleration factor = Number of subsets
![Page 9: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/9.jpg)
Acceleration with Ordered Subsets (OSEM)
Allessio A. & Kinahan P., in Henkin R. (ed.), Nuclear Medicine, 2nd ed., 2006.9
![Page 10: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/10.jpg)
PET point spread function (PSF) modelling
![Page 11: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/11.jpg)
PSF modelling
Casey M. (2007) Siemens Molecular Imaging
Radial distance (cm)
Ave
rage
Res
olut
ion
(mm
FW
HM
)
11
![Page 12: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/12.jpg)
Casey M. (2007) Siemens Molecular Imaging
Anthropomorphic Torso Phantom with four 12mm 1.4 MBq 68Ge spheres in warm background.
PSF
AW-OSEM
PSF modelling – realistic conditions
AW-OSEM PSF
Distance from center (mm)
Lesi
on to
Bac
kgro
und
12
![Page 13: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/13.jpg)
PET resolution recovery with OSEM
Le Meunier L et al., J Nucl Cardiol 2010;17(3):414-426
OSEM +RR
OSEM
13
![Page 14: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/14.jpg)
SPECT Hardware Advances
![Page 15: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/15.jpg)
Dedicated cardiac imaging systems• Optimized for cardiac imaging• New solid state detectors• Multi-pinhole or high-sensitivity parallel-hole
collimators.
Goals• reduced acquisition time • reduced radiation dose
15
![Page 16: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/16.jpg)
Cadmium zinc telluride (CZT) detectors
• high count rate capability (> 10 million photons/s/mm2).• superior intrinsic spatial resolution (~2.5mm FWHM)• superior resolution (~1.5% @ 140 keV)• expensive. • Convert -ray energy directly to electrical signal – no need for
PMTs.• enable smaller and more efficient devices
16
![Page 17: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/17.jpg)
D-SPECT (Spectrum Dynamics)
• Detector columns swivel through 110º
• Pixelated as 16x16 CZT elements.
• High-sensitivity parallel hole collimator
17
![Page 18: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/18.jpg)
Discovery NM 530c (GE)
• 19 pinhole collimators, each with 4 pixelated CZT detectors
• No detector motion
18
![Page 19: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/19.jpg)
IQ-SPECT (Siemens)
• Confocal collimators with conventional SPECT[/CT] camera.
• Converging holes magnify the heart
• Sensitivity more than double conventional SPECT.
19
![Page 20: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/20.jpg)
Cardius 3 XPO (Digirad)
• 3 solid state detectors
• Pixelated CsI(Tl), silicon photodiodes
• Rotating chair
20
![Page 21: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/21.jpg)
Dedicated Cardiac SPECT cameras
• Better image resolution and improved count sensitivity than conventional dual-head SPECT systems.
• Improved sensitivity => shorter imaging times (or lower injected dose), dynamic studies.
Slomka PJ et al. Seminars in Nuclear Medicine. 2014; 44(4): 232-51. 21
![Page 22: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/22.jpg)
Attenuation correction• Offered by most vendors;
• IQ SPECT, NM 530c – SPECT/CT configuration available• Cardius 3 XPO – x-ray based system optional• D-SPECT – not available• If hardware unavailable AC can be performed using a separately acquired
CT scan.
Slomka P et al., Semin Nucl Med 44:232-251, 2014
22
![Page 23: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/23.jpg)
PET Hardware Advances
![Page 24: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/24.jpg)
PET/CT Cardiac Imaging
GE Discovery MI Siemens mCT
• F18-FDG for viability, N13- ammonia or Rb82 for perfusion imaging.• Higher spatial and temporal resolution, and sensitivity, than
SPECT• Combines structure and function• High-end CTs => CT-coronary angiography and calcium scoring.
Philips Ingenuity TF
24
![Page 25: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/25.jpg)
T1T2
c = speed of light2)12( cTTx
x0
Time-of-Flight (TOF) PET
Courtesy M. Conti, Siemens Medical Solutions
![Page 26: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/26.jpg)
Non-TOF TOF
Time-of-Flight (TOF) PET
![Page 27: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/27.jpg)
TOF and RR reconstruction (82Rb PET/CT)
Slomka, P. et al. J Nucl Cardiol (2005) 12: 66
OSEM with TOF and RROSEM
27
![Page 28: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/28.jpg)
PET/MR
• Concurrent imaging => simultaneous cardiac gating of PET and MR data.
• No radiation exposure from CT• Advanced functional and molecular cardiac imaging with MR• Deriving attenuation map is challenging• Electromagnetic fields problematic for patients with pacemakers,
implantable defibrillators.
Siemens mMRGE Signa PET/MR
28
![Page 29: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/29.jpg)
Conclusions
Software advances• Efficient iterative reconstruction algorithms with ability to model and
compensate for physical effects that degrade image quality, e.g.
• attenuation
• noise
• scatter
• spatial resolution loss
• motion
29
![Page 30: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/30.jpg)
Conclusions
SPECT Hardware• new dedicated cardiac SPECT systems give up to 2x improvement in spatial
resolution and 7x reduction of radiation dose or time compared with conventional SPECT.
• dedicated scanners are relatively costly.
• conventional SPECT systems will be around for a while
• some vendors offer retrofitting of dedicated cardiac collimators to conventional scanners.
• not all offer attenuation correction
30
![Page 31: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/31.jpg)
Conclusions
PET Hardware• Hybrid PET/CT
• New detectors - digital silicon photomultipliers (Si-PMs) and avalanche photodiodes (APDs) have enabled simultaneous PET/MR
• Si-PMs => good timing resolution
• TOF imaging
• Simultaneous PET/MR has entered the clinical arena.
• Time will tell its ultimate clinical role.
31
![Page 32: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/32.jpg)
Thank you
32
![Page 33: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/33.jpg)
33
![Page 34: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/34.jpg)
Recent PET state-of-the-art• Fast scintillators (LSO, LYSO) for improved high count rate performance, and
and better random rejection than previous BGO
• 3D acquisition for improved sensitivity
• Smaller detector elements for increased spatial resolution (~ 4.5mm FWHM)
• Large axial coverage (up to 25cm)
34
![Page 35: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/35.jpg)
SUMMARY
Recent software and hardware developments in nuclear cardiology have delivered many improvements.• Iterative reconstruction algorithms for improved image
quality and quantitative accuracy
• New detectors with improved high count rate performance, energy resolution and timing resolution
• Dedicated SPECT systems with improved sensitivity and spatial resolution
• Hybrid PET/CT and PET/MR systems with TOF and resolution modelling.
• All of these have already-established or potential benefits for cardiac imaging. Time will determine their ultimate role.
35
![Page 36: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/36.jpg)
Reconstructing Attenuation Map from Emission data
MLAA • Simultaneous iterative (maximum likelihood) reconstruction of
attenuation and activity Nuyts et al. IEEE Trans Med Imag 18(5): 393‐403, 1999.
• Both attenuation and activity derived from the measured emission data.
36
![Page 37: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/37.jpg)
TOF-PET data determine the attenuation up to a constant
CT-based attenuation
TOF-PET-based attenuation
37
![Page 38: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/38.jpg)
TOF-PET data determine the attenuation up to a constant
CT-based attenuation
TOF-PET-based attenuation
Exchanging contours reveals PET/CT mismatch38
![Page 39: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/39.jpg)
Dose Reduction - D-SPECT Simulation
Nakazato R et al. , J Nucl Med 2013; 54:373–379 39
![Page 40: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/40.jpg)
In and out pressure from ventilator
Gel with background activity
Inflatable balloon
Hot spheres attached to balloon (10mm diameter)
Vent
Methods: Tumor Phantom Model
PETExternal trigger
MR
“Beating Phantom”
Guerin and El Fakhri, Med Phys 2011
![Page 41: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/41.jpg)
Tumor Phantom Results: Motion estimation
Source Target Estimated motion
![Page 42: Software and Hardware Advances in Nuclear Cardiology...2016/10/12 · Software and Hardware Advances in Nuclear Cardiology Department of Medical Physics, Westmead Hospital, Sydney](https://reader034.vdocuments.us/reader034/viewer/2022050110/5f47c7883e4d2a6e5120663f/html5/thumbnails/42.jpg)
Methods: Tagged MR
GRE sequence GRE sequence with tagging
Tagging patterns provide additional motion information.