PET-MRI: Device & Clinical Applications

PET/MRI

Device and Clinical Applications

Jiraporn Sriprapaporn

Siriraj Hospital, Bangkok (Last update in December 2016)

Jiraporn_PET/CT Onco 2016

PET/MRI

PET/MRI is a hybrid imaging technology that combines the molecular and functional information of PET with the soft-tissue contrast of MRI.

PET/MRI article was first published in 1997, predates the emergence of clinical PET/CT in 2001.

Challenges of PET-MR: A fundamental problem to overcome is that photomultiplier tubes (PMTs) do not function within the strong magnetic field required for MR imaging (MRI).

Muzic RF Jr 2014 https://www.ncbi.nlm.nih.gov/pmc/arti

cles/PMC4451572/


Clinical PET/MRI

The first brain-only prototype PET/MRI imaging system was installed by Siemens for research use in the late 2000s.

Clinical body PET/MRI imaging. The first Philips Healthcare Ingenuity TF PET-MR was installed at Mt. Sinai

Medical Center in New York as an alpha system in 2009 and then in its clinical configuration in January 2010.

The first Siemens Biograph mMR was installed at the Technical University of Munich in November 2010.

GE installed its PET-MR scanner, called a PET/CT + MR, at University Hospital Zurich in 2011.


At the beginning 3 vendors

SIEMENS

PHILIPS

GE Healthcare 2 machines in 2 rooms

1 machine- 2 gantries

1 machine- 1 gantry


Ingenuity TF PET/MR

Received European CE Mark in January, 2011

3.0 Tesla MRI

TF PET:

495 picoseconds is the fastest timing resolution of any Philips TOF system.

The fast timing resolution enhances image quality by reducing noise and providing higher sensitivity leading to enhanced localization of events for high image quality.

http://www.youtube.com/watch?v=Cm4554b4lsQ

PHILIPS

RSNA 2010


From Concept to Reality Simon R. Cherry and his colleagues first conceptualized the PET/MRI fusion in 1996 and developed a rudimentary prototype one year later. http://www.radiologytoday.net/archive/rt060208p20.shtml

FDA Gives Green Light to Simultaneous PET/MRI System_6-2011

With simultaneous acquisition by both modalities, a fused dataset is available automatically, but, at the same time, both datasets can be viewed separately.

It is possible to do an assessment of oncologic disease in the head and brain, and the whole body,"

Goal : To have Biograph mMR commercially available worldwide by 2012.

Siemens Biograph mMR system

http://www.medscape.com/viewarticle/744402


SIEMENS:Biograph mMR

The world’s first system to combine MRI & PET in one scanner.

simulataneous scanning the “m” stands for molecular

FDA approval on June 10, 2011


GE PET/CT+MR Trimodality Solution

GE’s system is essentially

involves a dockable table

which passes through

their MR scanner followed by the PET-CT scanner.

2 machines in 2 rooms


PET-MRI Manufacturers

Currently 4 companies

Philips Healthcare, Andover, MA: The Philips Ingenuity TF PET/MR

Siemens Healthcare, Erlangen, Germany: The Biograph mMR

GE Healthcare, Waukesha, WI: The Discovery PET/CT 690 + Discovery MR 750, SIGNA PET/MR

MR Solutions, Guildford, UK: MRS-PETTM

Cubresa company offers an MR-compatible preclinical PET scanner called NuPET™

https://en.wikipedia.org/wiki/Positron_emission_tomography%E2%80%93magnetic_resonance_imaging


PHILIPS: Ingenuity TF PET/MR

The program to develop a combined

PET/MR system was formally launched

in 2007, after which Philips was the

first to bring a PET/MR system to

market when CE Mark in Europe was

earned in January 2011.

Mount Sinai and University

Hospitals/Case Western Reserve

University in Cleveland will be the first

to receive the Ingenuity TF PET/MR

system in the U.S.

3.0T MRI


Siemens: Biograph mMR

Biograph mMR received a CE mark and FDA approva for customer purchase in 2011.

3.0T MRI


GE Healthcare: SIGNA PET/MR

The GE system (SIGNA PET/MR) received its 510K & CE mark in 2014.

3.0T MRI


MR Solutions: MRS-PETTM PET/MRI preclinical scanners

MR Solutions developed the first commercial range of 3T and 7T cryogen free superconducting systems.

The company, based in Guildford, in the UK, is the world’s largest independent developer and manufacturer of 3T to 7T preclinical MRI bench top systems and spectrometers.

In 2012, the company developed the world’s first commercially available high-performance 3T preclinical MRI bench top scanner using super-conducting magnets which eliminates the need for liquid helium cooling.

It has also cut the scanner’s stray magnetic field so that other laboratory equipment can be safely operated within centimetres of the unit.

A more powerful 7T range followed in 2014.

http://www.mrsolutions.com/products/imaging-systems/


CUBRESA: NuPET™

One company, Cubresa, offers an MR-compatible preclinical PET scanner called NuPET™ for use in the bore of an existing MRI, enabling simultaneous PET/MR image acquisition.

http://www.cubresa.com/products/nupet/


Clinical Applications of PET/MRI

MRI has better soft tissue contrast than CT, warranting the use of PET/MRI rather than PET/CT when this characteristic is important.

Prospective areas of application include, in particular,

Oncology,

Cardiology

Neurology.


PET/MRI in Oncologic Applications

Pediatric patients and pregnant women

To reduce overall radiation exposure to the patient.

When using PET/MR, the radiation dose from CT is omitted and the actual radiation exposure is limited to the radiation dose from the PET component only (which is substantially minor in comparison to the radiation dose from CT)

Neurologic and head & neck applications

Brain tumors: 11C-methionine or 68Ga-DOTATOC radiopharmaceuticals could be reliably used in PET imaging of intracranial tumors simultaneously with MRI

Head and upper neck cancers : Increased detailed resolution and improved image contrast could be found in the PET images of the PET/MRI system in comparison to the standard PET/CT

The strongest evidence for a clinical indication of PET/MRI exists in the head & neck cancer population.

For local staging the high spatial and contrast resolution of MRI can delineate the tumor extent and lymph node involvement from surrounding normal tissue in the complex head and neck anatomical region.

This may lead to a superior primary tumor staging (T-staging) and regional lymph node staging (N-staging).

Furthermore PET/MRI can be useful for radiation therapy and presurgical treatment planning in head and neck cancer patients.

Partovi S 2014



Chest

Superior sulcus tumors: the combination of high spatial resolution MR imaging for the involvement of the brachial plexus and spine

Abdomen and pelvis

Liver lesions

MR has shown a superior sensitivity for the detection of focal liver lesions, especially when <1 cm in size.

PET/MRI an excellent method to screen for metastases (Figure 1) or monitor embolization therapy for liver lesions (PET can provide information on their potentially neoplastic nature)

Liver screening in colorectal cancer reduces patient mortality by 25%.

Pancreatic, biliary and upper gastrointestinal neoplasms

Partovi S 2014


Figure 1: Staging PET/MRI scan of a 56-year-old woman with known ovarian cancer. Axial and coronal T2 weighted images (A and B) show multiple intermediate to high signal lesions abutting the liver posteriorly (long arrow), occupying the porta hepatis (short arrow) and seeding the peritoneum (arrowheads). A round, well defined lesion with similar characteristics is also seen in segment IV of the liver (dotted arrow). On PET/MRI images (C and D) the lesions previously described, and others not so apparent, are revealed by high FDG uptake confirming their malignant nature. MIP of the whole body (E) shows multiple lesions both in the chest and abdomen.

Partovi S 2014



Abdomen and pelvis (cont)

Pelvic oncologic diseases such as

Gynecologic malignancies,

Prostate cancer esp. when using C-11 choline, F-18 choline or C-11 acetate

Rectal cancer


Figure 2: Re-staging PET/MRI scan of a 56-year-old woman with ovarian cancer. Coronal T2 fat saturated weighted image (A) and axial T2 weighted image (B) demonstrate a large heterogeneous lesion with cystic and solid components in the right adnexal area suspicious for malignancy. PET/MRI fusion images (C and D) show FDG uptake of the solid component confirming malignant suspicion. Maximum intensity projection (MIP) whole body image (E) shows diffuse spread throughout the abdomen and pelvis. The round FDG positive pseudolesion in the right lung corresponds to the chemotherapy infusion port.

Partovi S 2014



More details on oncologic applications can be found in the article below.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4915069/


PET/MRI in Musculoskeletal Imaging

Neoplastic Conditions

Sarcoma

Osseous metastases

Lymphoma

Multiple myeloma

Non-neoplastic conditions

Infectious and inflammatory conditions



PET/MRI for Neurological Applications

Brain Tumors

Dementias/Neurodegeneration

Stroke/Cerebrovascular disorders

Epilepsy

Neurobiology of Brain Activation

Translational Research



PET/MRI for Cardiovascular Applications

CAD

Detection of CAD

Myocardial viability imaging

Myocardial infarct

Carotid atherosclerosis

Hereditary, infiltrative and inflammatory cardiovascular diseasessclerosis

Hypertrophic cardiomyopathy (HCM)

Amyloidosis

Cardiac sarcoidosis


Quant Imaging Med Surg 2016;6(3):297-307

PET-MRI: Device & Clinical Applications

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