PETMR Pooley FLAAPM Fall... · • Lutetium based scintillator (4 x 5.3 x 25 mm^3) with analog SiPM • 10.5% energy resolution • 390 ps average timing resolution • Transverse

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©2014 MFMER | slide-1

PET/MR:Technology, Installation and Clinical Practice

Robert A. Pooley, PhD, Brad Kemp, Ph.D, Kris Gorny, Ph.D., Anshuman Panda, Ph.D., Gene Paden, M.S., Judy James, Ph.D.

FLAAPM Fall Meeting, Daytona Beach Shores

September 9, 2016


Disclosure

• Nothing to disclose

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Catana

PET/MR Systems

GE SIGNA PET/MR


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GE SIGNA PET/MR

• MR• 3T Discovery 750W• 70 cm bore• PET compatible array coils

• PET• Time-of-flight• 60 cm transverse FOV• Lutetium based scintillator (4 x 5.3 x 25 mm^3) with analog

SiPM• 10.5% energy resolution• 390 ps average timing resolution• Transverse spatial resolution = 4.5 mm


Positron Imaging

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Positron Imaging

Total Events = Trues + Scatter + Randoms


GE SIGNA PET/MR

• MR• 3T Discovery 750W• 70 cm bore• PET compatible array coils

• PET• Time-of-flight• 60 cm transverse FOV• Lutetium based scintillator (4 x 5.3 x 25 mm^3) with analog

SiPM• 10.5% energy resolution• 390 ps average timing resolution• Transverse spatial resolution = 4.5 mm

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©2014 MFMER | slide-9Kemp


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Motivation for Combining PET and MR

• MR provides preferred image contrast for some anatomy

• brain, breast, prostate, abdomen• Single modality scan preferred over multiple scans

for patient, with improved co-registration.

• Decrease in dose for at-risk populations• No CT scan

• Improvements in PET image quality• MR based motion correction• MR based partial volume effect correction

©2014 MFMER | slide-12Catana

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©2014 MFMER | slide-14Catana

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Catana


How MR and PET Can Affect Each Other

• How MR can affect PET• Main magnetic field (PET detector failure)• Gradient fields (eddy currents, heating, vibration)• RF interference (drop in PET count rate)

• How PET can affect MR• Susceptibility artifacts (B0 inhomogeneity, linearity of

gradient fields)• RF interference (artifacts from PET electronics)

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Challenges

• MRI compatible PET detectors• Typical PET scanners use photomultipliers

which do not operate well in magnetic fields• Development of solid state photo detectors

• Avalanche photodiodes (APDs)• Silicon photomultipliers (SiPMs)• Immune to magnetic fields due to short

path of charge carriers


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Challenges

• Quantitative imaging• PET attenuation correction requires linear

attenuation coefficients at 511 keV.• CT data from PET/CT can easily be

transformed to linear attn. coefficients• More difficult in PET/MR

• Distinguishing bone from air filled cavities is a particular challenge

• UTE sequences will improve this in future


Attenuation Correction Techniques

• MRI – Segmentation

• MRI – Atlas

• MRI – UTE

• PET – Emission

• PET – Transmission

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MRAC

Kemp


MRAC

Kemp

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PET/MR Installation

• Design considerations• As simple as combining nuclear medicine facility

with MR facility• Shielding

• Magnetic field• RF interference• Acoustic noise• Radiation protection

• MR access – 4 Zones• Ferromagnetic detector• Uptake areas, MR-only patient waiting areas


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PET/MR Acceptance Testing

• Primarily separate MR and PET testing

• MR• ACR Phantom• Coil QC• RF noise• Acoustic noise• Magnetic fringe field

• PET• NEMA NU 2-2007. Manual and Software analysis provided with

system.• Image quality, Accuracy of Attenuation, Scatter Corrections• Spatial Resolution• Sensitivity• Scatter Fraction, Count Losses, Randoms Measurement

• Simultaneous PET/MR Tests: co-registration, PET stability with EPI

MR system Passed all tests except one coil that was not installed properly, and excessive acoustic noise in control room.

PET system Passed all tests

Simultaneous PET/MR Passed

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ACR PET Phantom


ACR PET Phantom

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NEMA - Image Quality


NEMA - Accuracy

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NEMA - Scatter Fraction


NEMA - Sensitivity

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NEMA - Spatial Resolution


PET/MR Clinical Practice

• Scan Protocol

• Clinical Indications

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Catana

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Clinical Protocols and Indications -Oncologic

• Torso Survey PET/MR plus Focused Brain PETMR:

• Advanced Lung Cancer• CNS Lymphoma• Metastatic Melanoma• Cancer with Brain Metastases

• Torso Survey PET/MR plus Focused Abdomen PET/MR

• Pancreatic Cancer• Hepatic Cancer• Cancer with Hepatic Metastases


Clinical Protocols and Indications -Oncologic

• Torso Survey PET/MR plus Focused Pelvic PET/MR

• Endometrial Cancer• Ovarian Cancer• Cervical Cancer• Vulvar Cancer

• Torso Survey PET/MR plus Focused Brachial Plexus PET/MR

• Metastasis to Nervous System• Peripheral nerve sheath tumor of the brachial plexus• Neurolymphomatosis of the Brachial Plexus

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Clinical Protocols and Indications -Neurologic

• Focused Brain PET/MR• Intractable Epilepsy


Clinical Images

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Indication: Seizures. 5.4 mCi FDG

Broad areas of hypometabolism


15-year-old female with diagnosis of primary generalized epilepsy. 4.5 mCi FDG

Extensive area of decreased FDG activity; highly suspicious for a primary seizure focus

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CNS lymphoma, status post methotrexate, procarbazine, and Rituxan

Significant residual hypermetabolic CNS lymphoma

F-18 FDG, 10.81 mCi


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PET Brain from WB Survey PET Brain from Focused PET


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Restaging prostate cancer

Multiple choline avid foci worrisome for local seminal vesicle recurrence and pelvic nodal metastatic disease

C-11 Choline, 10.71 mCi

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Radiotracers

• [18F] FDG Clinical Metabolism

• [18F] Fluoride Clinical Bone scan

• [13N] Ammonia Clinical Myocardial perfusion

• [11C] Choline Clinical Prostate cancer

• [18F] FDOPA Research Cancer

• [11C] Acetate Research Myocardial metabolism

• [O-15] Water Research Perfusion

• [15O] Oxygen Research Metabolism

• [18F] FLT Research Proliferation; brain tumors

• [11C] Flumazenil Research GABAergic CNS


Radiotracers

• [11C] McN5652 Research SERT CNS

• [11C] HED Research Myocardial Innervation

• [11C] PIB Research Amyloid Beta CNS

• [18F] AV138 Research Amyloid Beta CNS

• [18F] Florbetapir Research Amyloid Beta CNS

• [18F] Flutemetamol Research Amyloid Beta CNS

• [11C] Palmitate Research Metabolism

• [18F] AV1451 Research Tau CNS

• [18F] FTHA Research Fatty acid uptake

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References

• Catana. “Integrated PET/MRI.” MGH/HST Center for Biomedical Imaging.

• Kemp, Gorny. “PET/MR System Overview.” Mayo Clinic, Rochester, MN.

• Vandenberghe, et. Al. “PET-MRI: a review of challenges and solutions in the development of integrated multimodality imaging.” Phys. Med. Biol. 60 (2015) R115-R154


Thank YouMayo Clinic Florida

[email protected]

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Documents

PETMR Pooley FLAAPM Fall... · • Lutetium based scintillator (4 x 5.3 x 25 mm^3) with analog SiPM • 10.5% energy resolution • 390 ps average timing resolution • Transverse