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Vol. 7 • Issue 2 • 2013•2
THE NEWSLETTER OF THE SNMMI CENTER FOR MOLECULAR IMAGING INNOVATION AND TRANSLATION
Simultaneous PET/MR: Early Experience
“Advancing a better understanding of radiation dose and risk and promoting dose optimization
in nuclear medicine and molecular imaging is a top priority for SNMMI,” said Frederic H. Fahey,
focus SNMMI
of the following
andcomponent
labeled lipoproteins
trace their
DSC,
president.review.
“The online resource istion
a key
of our dosetooptimization
We
have
referred
to
some
of
the
early
destination
in
the
inflammatory
cells in
initiative, as it compiles important information in an organized fashion in one central location.”
molecular
imaging
attempts
that
labeled
plaques
(1).
Even
though
the
incorporaThe online resource includes SNMMI journal articles, abstracts, educational offerings, news
white
cells toand
follow
localization
of radiolabeled
components
in the
articles,blood
presentations
linkstheir
to useful
websites,
as well
as other materials.
The resource
will
routine mMR
body exam
is generally
INwhole
THIS
ISSUE
completed in approximately 45-70 minutes
depending on the number of desired MR
LitBriefs
2
sequences, the field of view imaged and the
size of patient. PET and MR
acquired
MI indata
the are
News
4
simultaneously which improves image coSNM to Sponsor
5
registration compared to PET/CT (a paper
demonstrating this
been
submitted by
Newhas
RECIST
Guidelines
6
our group). We also hypothesize that this
7
MI Journal
type of acquisition will allow for improved
Calendar multi8
quantification and more MIaccurate
parametric assessment of lesions. Standard
bed positions include head/neck, thorax,
plaque
mayand
not have
adequate,
abdomen,
pelvisbeen
with
other these
areas
studies
created
a
sound
foundation
for and
the
depending on the patient’s disease stage
development
of
imaging
strategies
of
the
study indication. Our institution has also
future.
performed several localized studies; the most
frequent being brain PET/MR for evaluation
Pathologic
of Inflammation
of epilepsy Basis
and dementia.
Dedicated
Imaging
pelvic, neck and liver protocols are under
Vulnerableand
plaques
have promise.
typically large
development
show great
necrotic cores that are covered by thin fibrous caps (2). Many foam cells are seen
around the necrotic cores. There is extenContinued on page
2. Seethe
Simultaneous
sive inflammation
within
fibrous PET/MR
caps;
the more macrophages, the thinner the cap.
Migration of monocytes to the subintimal
layers of the plaque is associated with development of receptors for chemoattractant
factors, such as monocyte chemotactic protein-1 (MCP-1); adhesion molecules, such as
vascular cell adhesion molecule-1 (VCAM-1)
JNM
& JNMT App
(1); and expression of
scavenger
receptors,4
including SRAI/II, CD68 and FcRIII.
MI References
In addition to upregulation
of various sur-4
face receptors, foam cells in the neointima
release numerous cytokines,
such
as inter-5
MI in the
News
leukin-1, tumor necrosis factor-� and MCP1 (3). Activated macrophages also release
metalloproteinases and Tech
otherCorner
proteolytic6
enzymes, such as cathepsins, which lead to
degradation of the matrix,
of the fi-8
CMIITthinning
Education
brous cap and positive outward remodeling
of the vessel wall. Cell death is commonly ob-
Continued on page 5. See Online Dose.
Continued on page 2. See Plaque.
R
FDA Moves Forward on Imaging
Amyloid in the Brain
ecently a new integrated whole-body PET/MR will develop in to a powerful routine
positron emission tomography (PET)/ clinical imaging tool for both whole body and
magnetic resonance (MR) system capable focused exams.
of simultaneous PET and MR imaging
was approved by the U.S. Food and Drug
PET/MR
System
Basics
he pastuse
several
years have
seen tremendous
advances
in the deAdministration for human
(Biograph
The principle difference in the PET
mMR, Siemens, Germany).
This
velopment
of instrument
new radiopharmaceuticals for molecular imaging with
component of the PET/MR system as
is capable of multi-station
hybrid
PET/MR
positron emission
tomography
(PET). Despite
the largePET/computed
number of
compared
to standard
body imaging as well as single-bed dynamic
tomography
cameras ishowever,
that the detector
pre-clinical and early clinical
studies in (CT)
the literature,
only
PET and multi-sequence MR scans. The mMR
replaces standard photomultiplier tubes with
generates temporally and spatially aligned
Continued on page 2. See FDA.
MR-compatible avalanche
photodiodes. The
anatomic and physiological datasets for use
PET component has a transaxial field-ofin diagnosis and disease monitoring. There
view of 59.4 cm and an inner detector ring
are many proposed applications in oncology,
diameter of 65.6 cm. The MR component is
neurology, cardiology and other fields for
outfitted with a 3.0 tesla magnet with a statewhich this simultaneous imaging will prove
of-the-art gradient and RF system capable of
advantageous.
performing spectroscopy, functional MR and
The New York University (NYU)
numerous other advanced MR techniques.
Department of Radiology installed an
mMR in the summer of 2012 and the first
imaging
composcavenging of insudated
lipid, oversee their
Imaging
patientolecular
was scanned
in of
latevarious
July. Since
this PET/MR
nents
of
atherosclerotic
plaques
has
been
transformation
to
foam
cells
or mediate
Due mainly to the complexity
of cell
MR
time we have imaged over 200 patients on
proposed,
and
proof
of
principle
has
been
death
(1).
various research protocols. Our preliminary acquisitions during PET/MR, whole body
demonstrated
in experimental
models
of exams
Molecular
targets
also studies.
included
take longer
thanhave
PET/CT
A
experience
strongly
suggests that
hybrid
disease (1). These preclinical studies have events that are associated with or consepredominantly targeted plaque inflamma- quent to inflammation, such as production with the premise that the extent of tion of cytokines and metalloproteinases.
inflammation would determine the vulner- Although these experimental molecular
ability of the plaque to rupture. Plaque in- imaging studies have offered significant
flammation has been detected by targeting promise, translational data in the clinical
alterations in monocytes that facilitate their setting has just started to emerge. Clinical
migration to the neointima, ensure efficient studies of molecular targeting are the major
T
Clinical Feasibility of Molecular
Imaging of Plaque Inflammation
in Atherosclerosis
M
SNMMI Launches Online Dose
Optimization Resource
T
he Society of Nuclear Medicine and Molecular Imaging (SNMMI) has launched a new
online resource
imaging professionals,
referring
physicians
and the vascular
public on dose
The likelihood
that for
atherosclerotic
plaques
will result
in acute
optimization for nuclear medicine and molecular imaging procedures. The information,
available
at www.snmmi.org/dose,
is designed
to help ensure traits
patients
the smallest
events
is intimately
associated with
the morphologic
ofreceive
the plaque
possible amount of radiopharmaceutical that will provide the appropriate diagnostic
andinformation.
the extent of inflammation.
Amyloid in the Brain
IN THIS ISSUE
Calendar
10
Simultaneous PET/MR. Continued from page 1.
In each acquisition bed, an approximately 20-second breathhold MR attenuation correction map is acquired utilizing a T1Dixon-based segmentation model, which segments the acquired
data in to air, lung, fat, and soft tissue. Immediately afterwards,
the diagnostic MR sequences are acquired depending on the
application. For example our standard oncology protocol typically
includes T1 TSE, T2 STIR, T1-weighted gradient echo imaging
and diffusion weighted imaging (DWI). PET data is acquired
simultaneously during the MR sequences in free breathing.
Imaging time is usually six to eight minutes per bed which is
driven by the number of MR pulse sequences that are to be
acquired rather than the PET count statistics.
Fig 1 – 54-year-old male with melanoma and FDG-avid soft tissue focus in the
right gluteus maximus on PET/CT (1A, B, C) without CT correlate. PET/MR shows
the FDG-avid focus correlates to a T2 bright (1E - T2 Blade) nodule with restricted
diffusion (1F - DWI), demonstrating the superior soft tissue contrast of PET/MR.
The Future of PET/MR
2
The authors hypothesize that PET/MR will develop into a powerful
routine clinical tool for many specific applications in the next few
years; it may even replace PET/CT for some specific indications. PET/
MR will be exceptional for applications in which PET/CT use is limited
due to reduced CT soft-tissue contrast. For example, the superior MR
soft tissue contrast will be beneficial for head and neck cancer, thyroid
cancer, lung cancer with suspicion of chest wall invasion, gynecological
malignancies, anorectal cancer, and neurological/cardiac applications.
PET/MR will also excel in indications where radiation dose reduction
is critical, such as for pediatric and young-adult oncology applications.
There are future hopes for improved, multiparametric evaluation of
disease utilizing novel PET tracers and sophisticated quantitative MR
sequences with enhanced accuracy realized by precisely temporally
and spatially aligned data. New applications based on gated-MR open
up possibilities for improved quantification of PET using MR-based
displacement maps to motion-correct positron decays.
invasion compared to CT while the PET portion of a PET/MR may
remain superior for detection of metastatic lymph nodes. Abilities and
applications of thoracic PET/MR will continue to increase with more
rapid imaging, respiratory gating, and molecular imaging. In addition,
MR offers improved accuracy as compared to CT for detection of
metastases in the adrenals, brain and bones, common sites for lung
cancer metastases.2, 3
A general advantage to keep in mind is that the superior
soft tissue contrast of MR will allow for better delineation of
primary tumors in areas where CT is less accurate. Advanced
MR sequences will likely improve the staging and overall
assessment of brain tumors, prostate cancer, rectal cancer and
gynecological malignancies, combining the high resolution of
MR for delineation of primary tumor with the superior sensitivity
of PET for detection of nodal and distant metastases. Similarly,
PET/MR will be beneficial for evaluation for liver lesions, as MR
is more sensitive for detection of liver metastases while PET may
excel at assessing treatment response.
Clinical cardiovascular assessment with PET/MR is an exciting
area of research. Protocols under development are anticipated to
permit comprehensive evaluation of cardiac function, coronary artery
perfusion, cardiac inflammation and innervation, and other cardiac
pathophysiological processes. MR will supply exceptional anatomical
correlation, precise information about cardiac perfusion and injury
and will allow for improved gating and quantification of PET tracers.
Considerable PET/MR clinical research is ongoing for neurological
applications including the evaluation of cerebral perfusion, epilepsy,
dementia and various psychiatric disorders. Simultaneous PET/MR
acquisition has the potential to offer a thorough evaluation of cerebral
pathophysiology on a molecular, anatomical, and functional level.4,
5
Hybrid simultaneous PET/MR allows the potential to accurately
correlate time-variant functional MR data (fMRI) and PET tracer
studies with a wide range of tracers such as 15O-H2O, FDG, FLT and
receptor-imaging agents.
Specific Applications of PET/MR
PET/MR is expected to be useful in lung cancer. Accurate
assessment of chest wall invasion is critical for the thoracic surgeon;
unexpected invasive disease can lengthen the operation time and
significantly modify the surgical procedure.1 It is hypothesized that
the superior image contrast obtained at MR will allow for excellent
delineation of the primary tumor (T-stage) and better detect chest wall
www.snmmi.org/cmiit mi
Fig 2 – 67-year-old male with prostate cancer and widespread osseous metastases
on 18F-NaF PET/MR. This study illustrates the high level of image detail achieved by
PET/MR; arrow shows 18F-NaF avid left femoral intertrochanteric metastases correlating to hypointense lesion on T1 TSE (2A), hyperintense lesion on STIR (2B) and
on fused NaF/T1 TSE image (2C).
Continued on page 3. See Simultaneous PET/MR.
Simultaneous PET/MR. Continued from page 2.
Ongoing Challenges of PET/MR
As with any novel technology there are some limitations with
PET/MR. One area of further development will be optimization
of attenuation correction of PET/MR images which is necessary for
accurate reconstruction and precise calculation of SUV (standardized
uptake value). Currently applied T1-Dixon-based attenuation
correction sequences do not provide bone attenuation correction
values; this originates from the lack of cortical bone signal on
conventional MR sequences.6 Research is currently ongoing to resolve
this issue by using ultrashort echotime sequences to delineate osseous
structures.
Another challenge faced by PET/MR is the limited MR sensitivity
for detection of small lung nodules compared to CT. To address this
issue, new fast MR sequences are under development at NYU and
elsewhere that can detect subcentimetric lung nodules with better
accuracy and reduced motion artifact. Future PET/MR studies will
need to examine the clinical implications of increased sensitivity in
the brain, liver, breast and other structures combined with potentially
lower sensitivity for small pulmonary nodules.
less anatomical detail regarding treated tumors. Small metastases are
better localized, and young patients with neurofibromatosis are already
benefitting from better characterization of benign and malignant
tumors. SUVs correlate well with those obtained at PET/CT and
there is little difference between PET/CT and PET/MR with respect to
visual interpretation of the PET data. We expect that 2013 will be the
year in which PET/MR becomes a routine clinical exam for select
applications. Scanner accreditation by the Intersocietal Commission
on Accreditation of Nuclear Laboratories and the American College
of Radiology will be key to a future in which PET/MR reimbursement
becomes a reality.
Conclusion
Hybrid simultaneous PET/MR is a promising new technology
with broad applications in the fields of neurology, cardiology and
oncology. Our institution’s current research protocols result in a
total imaging time of approximately one hour, making this a lengthy
but feasible exam. Further development of MR-based attenuation
correction should improve quantification, and faster MR sequences
may allow for improved patient throughput. The use of MR with
PET, as opposed to CT, allows for superior lesion characterization
in several applications, potentially improves functional quantification
and significantly reduces radiation exposure. We are just discovering
the tip of the iceberg for applications of PET/MR and we eagerly
look forward to working with collaborators to drive this technology
forward and improve the lives of patients.
Fig 3: 71-year-old male with memory loss. Multisequence FDG PET/MR (3A)
demonstrates temporoparietal grey matter hypometabolism characteristic of AD,
left greater than right. Fused PET/SWI (3B) demonstrates susceptibility artifacts
(arrows - small hypointense foci) compatible with amyloid angiopathy superimposed on AD.
Radiation Risk
The general public and medical community is becoming more
aware of the potentially detrimental effects of ionizing radiation used
in medical imaging. To ensure the best level of imaging care, it is
imperative that the medical imaging community makes every effort
to achieve the lowest possible radiation exposure for patients. A total
body adult PET/CT results in an effective dose of 20 – 25 milliSieverts7
and the CT portion accounts for half of the total exposure. The
significantly lower radiation exposure from PET/MR is a fundamental
advantage for its future advancement in oncology, neurology and
particularly pediatric applications.
Emerging Clinical Benefits
Patients imaged on our mMR scanner are currently all enrolled
in IRB-approved research protocols. We are already witnessing the
clinical benefits of this technology in our volunteers. Dementia patients
and the doctors that care for them are learning more about comorbid
conditions identified by the advanced MR research sequences.
Diagnostic confidence for routine oncological imaging interpretation
is improved in some cases where PET/CT was equivocal or provided
Rajan Rakheja, MD and Kent Friedman, MD
Division of Nuclear Medicine, Department of
Radiology, New York University
Langone Medical Center, New York, NY
REFERENCES
1
Williams DE, Pariolero PC, Davis CS et al. Survival of patients surgically treated for stage
I lung cancer. J Thorac Cardiovasc Surg 1981;82:70-76
2
Schwenzer N, Schrami C, Muller M. Pulmonary Lesion Assessment: Comparison of WholeBody Hybrid MR/PET and PET/CT Imaging – Pilot Study. Radiology 2012;264:2
3
Both M, Schultze J, Reuter M et al. Fast T1- and T2-weighted pulmonary MR-imaging in
patients with bronchial carcinoma. Eur J Radiol 2005;53(3):478–488
4
Stegger L, Martirosian P, Schwenzer N et al. Simultaneous PET/MR imaging of the brain:
feasibility of cerebral blood flow measurements with FAIR-TrueFISP arterial spin
labeling MRI. Acta Radiol. 2012 Nov 1;53(9):1066-72. doi: 10.1258/ar.2012.120191.
5
Heiss WD, Sobesky J, Hesselmann V. Identifying thresholds for penumbra and irreversible
tissue damage. Stroke 2004;5:2671–4.
6
Samarin A, Burger C, Wollenweber SD et al. PET/MR imaging of bone lesions--implications
for PET quantification from imperfect attenuation correction. Eur J Nucl Med Mol
Imaging. 2012 Jul;39(7):1154-60.
7
DeGrado TR, Turkington TG, Williams JJ et al. Performance characteristics of a
whole-body PET scanner. J Nucl Med 1994; 35:1398 –1406
3
JNM and JNMT Full Text iPad/iPhone App Now Available!
T
he Society of Nuclear Medicine and Molecular Imaging (SNMMI),
in conjunction with HighWire Press, has created a full-text mobile
application for SNMMI’s journals, The Journal of Nuclear Medicine
(JNM) and the Journal of Nuclear Medicine Technology (JNMT).
Compatible with iOS devices (iPad, iPod Touch and iPhone),
the application is available for download at the iTunes App Store.
SNMMI members and journal subscribers are able to download and
use the application for free as a benefit of society membership and
journal subscription, and non-members can download and access the
application for no charge during an extended trial period.
The SNMMI journals application will provide users with the
ability to download, search, view, and save abstracts and full-text
articles, including publish-ahead-of-print articles. In addition to
accessing the latest journal content both as full-text HTML and as
PDF, users can also access supplemental material, subscribe to and
follow JNM- and JNMT-related news feeds, bookmark content and
share articles via e-mail.
The JNM and JNMT journal application is technically robust:
• Articles optimized for the iOS and available in PDF format
• Full-screen images and figure-only/table-only views
• Internal hyperlinks to allow easy jumping within article
sections, images and references
• One-button access to publish-ahead-of-print articles
• Automatic tracking of viewing history
• Ability to mark and store favorite articles
• Sharing feature that allows the reader to e-mail to self for
later reference
• Capacity to increase or decrease font size for easier reading
For other mobile devices, SNMMI journals can be viewed
through a mobile web interface available at www.snmjournals.org.
To download the app, please visit: https://itunes.apple.com/us/app/
snmmi-journals/id601831995?mt=8
m i References
Each month, the CMIIT Editorial Board selects the top molecular imaging research papers from all papers indexed by PubMed. Below are recent papers on molecular imaging research.
The links below go to these references, including their abstracts and links to the full paper on PubMed.
18F-FDG Labeling of Mesenchymal Stem
Cells and Multipotent Adult Progenitor Cells
for PET Imaging: Effects on Ultrastructure
and Differentiation Capacity.
Wolfs E, Struys T, Notelaers T, Roberts SJ, Sohni A, Bormans G, Van Laere
K, Luyten FP, Gheysens O, Lambrichts I, Verfaillie CM, Deroose CM.
4
A Comparative Evaluation of Ultrasound
Molecular Imaging, Perfusion Imaging, and
Volume Measurements in Evaluating Response
to Therapy in Patient-Derived Xenografts.
Streeter JE, Herrera-Loeza SG, Neel NF, Yeh JJ, Dayton PA.
Technol Cancer Res Treat. 2013 Jan 25. [Epub ahead of print]
Appropriate use criteria for amyloid PET: A
report of the Amyloid Imaging Task Force, the
Society of Nuclear Medicine and Molecular
Imaging, and the Alzheimer’s Association.
Johnson KA, Minoshima S, Bohnen NI, Donohoe KJ, Foster NL, Herscovitch P, Karlawish JH, Rowe CC, Carrillo MC, Hartley DM, Hedrick
S, Pappas V, ThiesWH.
Alzheimers Dement. 2013 Jan 26.doi:pii: S1552-5260(13)00034-4.
10.1016/j.jalz.2013.01.002. [Epub ahead of print]
Detection of fas-associated death domain and
its variants’ self-association by fluorescence
resonance energy transfer in living cells.
Wang S, Chen Y, Wu Q, Hua ZC. Mol Imaging. 2013 Feb 1;12(2):11120. PMID: 23415399 [PubMed - in process]
Efficient 18F Labeling of Cysteine-Containing
Peptides and Proteins Using TetrazineTrans-Cyclooctene Ligation.
Liu S, Hassink M, Selvaraj R, Yap LP, Park R, Wang H, Chen X, Fox
JM, Li Z, Conti PS.
Mol Imaging. 2013 Feb 1;12(2):121-8.
PMID: 23415400 [PubMed - in process]
Evaluation of backbone-cyclized HER2-binding
2-helix Affibody molecule for In Vivo molecular
imaging.
Honarvar H, Jokilaakso N, Andersson K, Malmberg J, Rosik D, Orlova
A, Karlström AE, Tolmachev V, Järver P. Nucl Med Biol. 2013 Jan 25.
doi:pii: S0969-8051(12)00320-4.
Fibrin-Targeted PET Probes for the Detection
of Thrombi.
Ciesienski KL, Yang Y, Ay I, Chonde DB, Loving GS, Rietz TA,
Catana C, Caravan P.
Mol Pharm. 2013 Jan 30. [Epub ahead of print]
www.snmmi.org/cmiit mi
Online Dose. Continued from page 1.
be promoted to SNMMI members through various communication
channels, promoted through social media and shared with referring
physician and patient groups.
In June, SNMMI kicked off the dose optimization initiative by
issuing a position statement that radiation dose for all nuclear medicine
and molecular imaging procedures should be optimized by ensuring that
the patient receives the minimum radiation dose necessary to provide
useful diagnostic information. The position statement recognizes that
the use of low levels of radiation in nuclear medicine procedures carries
some possible risk. However, if an appropriate procedure—one that can
provide the physician with clinical information essential to the patient’s
treatment—is not performed when necessary due to fear of radiation, it
can be detrimental to the patient.
Dose optimization has become a part of SNMMI’s communications,
outreach, advocacy and education efforts. This integrated approach
helps to provide information and guidance on dose optimization to
imaging professionals, referring physicians, policymakers and the public.
In addition to these activities, SNMMI continues to actively participate in
the Image Gently and Image Wisely campaigns.
“It is our firm belief that the ‘right test with the right dose should
be given to the right patient at the right time,’” noted Fahey. “We hope
that this online resource will provide professionals with tools they can
use to implement this into clinical practice and educate the public about
optimal dosing for nuclear medicine and molecular imaging procedures.”
MI in the News
MI Gateway presents a sampling of research and news of interest to the community of molecular imaging scientists. More molecular imaging news is available daily
at www.molecularimagingcenter.org.
PET Scan
Study Says
May
Reveal
C.T.E.
Signs,
For years, researchers have had to use tissue obtained posthumously to
diagnose chronic traumatic encephalopathy, or C.T.E., the degenerative brain disease that has bedeviled athletes, soldiers and others who
have sustained repeated head hits and concussions.
But a study published in The American Journal of Geriatric Psychiatry
on Tuesday suggests that PET scans could one day be used to diagnose
the disease in living patients.
Lymph Node Biopsy for Prostate Cancer Best
Planned with Hybrid Imaging
Sentinel lymph node (SLN) biopsies determining primary prostate
cancer metastases require diversified imaging techniques due to the
location of these lymph nodes buried within the pelvis and elsewhere.
As many as 44 percent of SLNs are located outside the pelvic region.
Hybrid near-infrared fluorescence and SPECT/CT or PET/MR may
provide some advantages before and during surgery, according to a
review in the March issue of The Journal of Nuclear Medicine.
Alzheimer’s Seen on Scans Decades Before
Dementia, Study Shows
Abnormal deposits in the brain thought to trigger Alzheimer’s disease can
be detected decades before the memory-robbing illness ensues, a finding
that will help guide future treatments, researchers in Australia said.
Doctors at Melbourne’s Austin Hospital followed 200 seniors, including people with Alzheimer’s disease and mild cognitive impairment,
for more than three years to chart any decline in cognition and brain
size against the deposition of abnormal protein in their brains. They
found it takes about 20 years for the deposits, known as amyloid beta,
to lead to dementia
PET Could Outshine Other Modalities for CAD
A growing consensus champions PET as the most effective imaging
technique for myocardial perfusion imaging and points to some very
clear advantages compared with SPECT for the detection of coronary
artery disease (CAD). Such improvements include sharper resolution
and the ability to glean meaningful myocardial blood flow reserve and
coronary flow reserve measurements. However, whether PET is truly
moving in on traditional CT and SPECT territory in clinical practice
remains to be seen.
Hepatic Function SPECT Testing Before and
During Radiotherapy Can Help in Treatment
Planning for Liver Cancer Patients
Monitoring the hepatic function of unresectable liver cancer patients
evaluated by 99mTc-labeled iminodiacetic acid (HIDA) used with single-photon emission computed tomography (SPECT) imaging before
and during radiation therapy provides critical data that could guide
more customized treatment plans and reduce risks of liver injury, according to recent research
Speedy In-Room PET Shows Potential for
Planning Proton Therapy
In-room PET scanning during proton therapy is feasible for monitoring treatment ranges and helps overcome logistical issues inherent
with transporting a patient to a PET scanner outside the treatment
room, according to a small clinical trial
5
PET/MR Primer for Nuclear Medicine Technologists
T
he rapidly advancing practice of molecular imaging offers
constant opportunities for nuclear medicine technologists to
learn about emerging imaging techniques. One of the newest devices
in our field is hybrid positron emission tomography (PET)/magnetic
resonance (MR), an imaging system that performs PET and MR
acquisitions together. This type of scanner provides nuclear medicine
with a tool that generates high quality molecular imaging datasets
and detailed, high-contrast structural images. One of the first types
of PET/MR scanners, the Siemens Biograph mMR™ was installed
at our institution, New York University Langone Medical Center
(NYULMC) in the summer of 2012 (Fig. 1). The first PET/MR scan
in the state of New York was performed at our Center for Biomedical
Imaging (CBI) on July 26, 2012, with more than 15 members of
a newly established PET/MR research team in attendance. This
team consists of nuclear medicine physicians, radiologists, Siemens
engineers and application specialists, researchers, MRI technicians,
and nuclear medicine technologists.
6
Fig 1 – William Fazio (MR technologist), Kimberly Jackson (NM technologist) and
Kamil Bani-Baker (MR technologist) in the PET/MR suite at NYULMC.
The Biograph mMR™ utilizes an array of avalanche photodiodes
rather than the photomultiplier tubes commonly used on PET
systems in order to be compatible with the strong magnetic fields
used in modern MR scanners. The design of the scanner is impressive
because it incorporates two historically incompatible modalities and
allows them to run simultaneously. The PET detectors fit along the
inner edge of the MRI bore, in between the RF body and gradient
coils. The inner diameter of the bore is 60 cm; this allows for high PET
system sensitivity and excellent MR image quality. While the slightly
smaller bore size compared to modern PET and MR systems has some
impact on patient comfort, the vast majority of patients are able to
tolerate the exam.
In New York state, all nuclear cameras (PET, single positron
emission computed tomography, etc.) must be operated by a licensed
nuclear medicine technologist. Currently there are no licensing
requirements for operating a MR scanner. To ensure compliance and
www.snmmi.org/cmiit mi
optimum scan quality, our PET/MR machine is jointly operated by a
nuclear medicine technologist and an experienced MR technologist.
The calibration, acceptance testing and daily quality control
measurements are similar to those of other PET systems and must
be completed each day by the nuclear medicine technologist. To
work in the PET/MR suite, MRI technicians have undergone training
in radiation safety in order to facilitate patient care and manage any
radiation-related emergencies. Nuclear medicine technologists learn
about MR safety and also MR scanning technology which is necessary
in order to work within the imaging team.
Both the MR and nuclear medicine technologists have extensive
experience as scientists in their chosen fields, but the differences
between PET and MR are great and there is a lot for both groups
to learn. This is an exciting challenge, and the combined PET/MR
technology has created a great opportunity for cross-training; both
types of technologists are able to work closely together and learn
from one another while ensuring an efficient workflow and excellent
patient experience. We are teaching and learning more and more
every day about the scanner and the various anatomical and molecular
acquisitions that PET/MR has to offer. The smooth functioning of
the imaging team is essential for a successful PET/MR department,
especially one that is constantly changing with new protocols and
increasingly diverse types of patients. We are pleased to report that
the merging of PET and MR technologist workflow has been a very
positive experience.
Since the first patient we have witnessed a high rate of utilization
of the PET/MR with a total of over 200 research subjects scanned. We
anticipate clinical referrals for PET/MR in the near future, supported by
our American College of Radiology (MR) and Intersocietal Accreditation
Commission of Nuclear Laboratories (PET) accreditation. The areas
of research focus currently are in neurology and oncology (Fig. 2).
The neurological research studies include evaluations for epilepsy,
dementia, brain tumors and psychiatric disorders. Oncological
research studies examine many diseases including breast cancer,
prostate cancer, myeloma, melanoma, sarcoma, and lung cancer.
There is much clinical excitement surrounding this new modality due
to its unique capabilities in combining high PET sensitivity for tumor
detection with excellent morphological and molecular information
from MR. The lower radiation exposure associated with PET/MR
compared to PET/CT shows great promise for pediatric imaging.
Many more research studies are being developed for PET/MR at NYU
to perform in the near future.
In the PET/MR suite, the responsibilities of the nuclear medicine
technologist include performance of routine tasks and accurate
record-keeping. Some of these activities include performance of daily,
weekly and quarterly PET quality assurance tests, acquiring patient
information, recording and storing all patient data, maintaining reports
on progress, reviewing patient images, performing risk management
Continued on page 7. See PET/MR Primer.
PET/MR Primer. Continued from page 6.
40
NAF18 BONE
35
LUNG
VOLUME
30
BREAST
WHOLEBODY
25
MYELOMA
20
MYELANOMA
LYMPHOMA
15
SARCOMA
10
ANAL/COLON/OVARIAN/RECTAL/RENAL
BRAIN
5
0
DIAGNOSIS
Figure 2 – Distribution of PET/MR cases at NYULMC as of February 2013.
assessments and networking with nuclear medicine physicians,
radiologists, referring physicians, engineers and management. At the
beginning of each day, we perform a daily quality assurance (QA) test
on the scanner. The daily QA is performed to ensure that the PET
scanner provides high quality and quantitative images of patients
while maintaining consistent diagnostic performance. The PET
technologist also performs the MRI daily quality control including MR
phantom measurements, checking the helium level (used for cooling
the magnet), and surveying the room and scanner for temperature
level, coil function, table position, and more. All of these help to
ensure patient safety as well as our own safety.
It is also the responsibility of the technologist to build and
maintain relationships with all who are involved in the research
process. This new technology has provided PET technologists with
an opportunity to interact with physicians, researchers, physicists,
engineers, administrators—and most importantly patients—in new
ways that advance our field and provide a fantastic opportunity for
personal development. As part of this interaction, PET technologists
have the opportunity to participate in a large number of research
projects, many of which require the preparation of special phantoms
and custom imaging protocols.
Effective operation of the PET/MR scanner for both research
and clinical scanning requires that one have a deep understanding
of how the data is acquired, reconstructed and stored. Because the
PET/MR system generates both MR and PET information during the
same study, the archival of large data sets has been challenging. Raw
PET data stored as sinograms generates files as large as 100MB, and
in list mode the files are massive; often larger than 10GB. Currently
we are archiving the PET raw data locally and not sending it to
the hospital PACS. Many of our research projects require multiple
list-mode reconstructions based on varying time intervals and
reconstruction settings.
Before scanning can proceed and the patient enters the scan room,
they must fill out a MR safety screening form which asks the patient
about metal implants, recent surgery, medical history, medications
and other questions. The patient is asked to remove all jewelry and
any clothing containing metal. All PET patients are injected with an
isotope such as 18F fluoro-deoxyglucose (18F-FDG) or 18F sodium
fluoride (18F-NaF). The patient is injected by the nuclear medicine
technologist and remains in a quiet room for 45 minutes of uptake
time. The patient is asked to void a few minutes before scanning and
is brought to the scan room. Patients are asked again to verify that all
metal objects have been removed and the staff is reminded again of
any possible metal implants to make sure they are safe for the PET/MR
scanner. The patient is secured on the scan table and provided with a
headset or earplugs to reduce the loud sounds produced by the MR
gradient coils. Unlike general MR scanning, we are unable to provide
music for the patient because this will affect the PET signal. It would
be of no use to play music in the room as would be done for PET
scans because the MR sequences generate a lot of noise in the room.
The patient is given instructions and made aware of the different coils
that may be used for their exam, such as a head coil or body matrix
coil. The patient is provided with an emergency ball and is informed
that both the MR and nuclear medicine technologists are present in
the external control room at all times during scanning.
One challenge in the PET/MR workflow is the positioning of RF
coils that are used with every PET/MR patient. The handling of the
coils is definitely a skill that the NM technologist needs to learn with
the system. Coils plug into specific locations on the patient table and
the various parts can cause attenuation artifacts in the PET images if
they are not positioned properly. One of our research projects has been
to evaluate the attenuation effects of the flexible surface coils. Of note,
due to the fact that the plastic housing of the coils has been thinned
in order to reduce the overall PET 511keV gamma ray attenuation,
some PET/MR sites have reported that fixed coils such as the spine
coil become warm during long studies. We have not encountered this
problem at NYULMC. Another special coil that is used for the PET/
MR system is a breast coil for localized studies with the patient in
the prone position. We need to take special care that the coil does
not push against the sternum or surgical wounds when patients have
Continued on page 10. See PET/MR Primer.
7
Featured CMIIT Activities at the 2013
SNMMI Annual Meeting
Educational programs sponsored by the CMIIT at the SNMMI Annual Meeting
Vancouver Convention and Exhibition Centre | June 8-12, 2013
8:00 AM-4:00 PM
Molecular Imaging in Neurodegenerative Diseases: State of the Art and Future Trends West - 208-209
8:00-8:30 AM
Joan Uronis: Patient Advocate Discussion (non-CE)
8:30-9:20 AM
William J. Jagust, MD: Overview of Biomarkers in the Clinical Evaluation of Dementia
9:20-10:15 AM
Andrew Siderowf, MD, MSCE: Overview of Biomarkers in the Clinical Evaluation of Parkinsonian Syndromes
10:15-10:30 AM
Break
10:30-11:20 AM
Christopher C. Rowe, MD, FRACP: Amyloid Imaging in Dementia
11:20-12:10 PM
Kirk A. Frey, MD, PhD: Dopaminergic Imaging in Parkinsonian Syndromes
12:10-1:00 PM
Lunch
1:00-2:00 PM
Daniel Skovronsky, MD, PhD: Imaging Biomarkers for Clinical Trials in Alzheimer’s Disease
2:00-2:15 PM
Break
2:15-3:00 PM
A. Jon Stoessl, CM, MD, FPCPC, FAAN: Imaging Biomarkers for Clinical Trials in Parkinson’s Disease
3:00-4:00 PM
Robert Henry Mach, PhD: New Targets and Tracer Development for Neurodegenerative Diseases
Sunday, June 9
8
11:00-12:30 PM
Emerging Technology Session #1- Translating Molecular Imaging (Non-CE Session) - West 306
11:00-11:30 AM
Lee Josephson, PhD: Translating Molecular Imaging - Nanoparticles
11:30-12:00 PM
NagaVaraKishore Pillarsetty, PhD: Translating Molecular Imaging - Nuclear
12:00-12:30 PM
Samuel Achilefu, PhD: Translating Molecular Imaging - Optical
12:30-2:00 PM
Translational Optical Imaging Modalities: Part I - West - 202-204
12:30-1:00 PM
Warren Zipfel, PhD: Feasibility and Possible Applications
1:00-1:30 PM
Harrison H. Barrett, PhD: Information Content of a Photon in Nuclear Medicine and Optical Imaging
1:30-2:00 PM
Anita Mahadeyan-Jansen: Intraoperative Detection of Tumor Margins with Optical Methods
12:30-2:00 PM
CMIIT Young Investigator Award Symposium - West 220
2:00-2:45 PM
CMIIT Business Meeting - West 220
2:45-4:15 PM
Radiopharmaceutical Sciences/Molecular Imaging/CMIIT Basic Sciences Summary Session West Building - 109-110
2:45-4:15 PM
Carolyn J. Anderson, PhD; Henry F. VanBrocklin, PhD; Jonathan McConathy, MD, PhD:
Radiopharmaceutical Sciences/CMIIT Basic Science Summary Session
4:30-6:00 PM
Translational Optical Imaging Modalities: Part 2 - West 201
4:30-5:00 PM
Samuel Achilefu, PhD: Fluorescence and Nuclear Imaging Agents
5:00-5:30 PM
Adam P. Wax: PhD: OCT and Mechanisms of Contrast
5:30-6:00 PM
Alexander Oraevsky, PhD: Octoacoustic Tomography: Basic Principals, Mechanism of Contrast,
and Clinical Applications
6:30-8:30 PM
RPSC/CMIIT Poster Mixer - Poster Hall Exhibit Hall A
www.snmmi.org/cmiit mi
Continued on page 9. See CMIIT Education.
CMIIT Education. Continued from page 8.
Monday, June 10
9:30-11:00 AM
Emerging Technologies Session #2: Clinical Trials for Intraoperative Imaging (Non-CE Session) - West 306
9:30-10:15 AM
Gooitzen M. Van Dam, MD, PhD: Translation of Optical Imaging into Clinical Setting
10:15-11:00 AM
Jonathan Sorger, PhD: Clinical Trials for Intraoperative Imaging
11:00-12:30 PM
Emerging Technologies Session #3: Neurodegenerative Imaging (Non-CE Session) - West 306
11:00-11:30 AM
Cornelia Beatrice Reininger, MD, PhD: AZD4694: A PET Biomarker for Brain Amyloid
11:30 -12:00 PM
Susan De Santi, PhD: Flutemetamol PET Imaging in Cognitive Impairment and Dementia
12:30-12:30 PM
Andrew W. Stephens, MD, PhD: Florbetaben PET Imaging in Clinical Trials: Update and Highlights
12:30-2:00 PM
PET/MRI - Now What? - Part I - West 213-214
12:30-1:15 PM
Simon R. Cherry, PhD: Introduction to PET/MRI
1:15-2:00 PM
Alexander R. Guimaraes, MD, PhD: PET/MRI - Where Are We Now? Where Will Be Tomorrow?
2:30-4:00 PM
PET/MRI - Now What? - Part II - West 213-214
2:30-3:00 PM
Peter Brader, MD: Clinical Applications - Pediatrics
3:00-3:30 PM
Alexander E. Drzezga, MD: Clinical Applications of PET/MRI Chances and Challenges - Oncology
3:30-4:00 PM
Pamela K. Woodard, MD: Clinical Applications of PET/MRI Chances and Challenges - Cardiology
4:30-6:00 PM
Multimodality Imaging - West 213-214
4:30-5:00 PM
Adrian Taruttis, PhD: Multispectral Optoacoustic Tomography
5:00-5:30 PM
Simon R. Cherry, PhD: PET/MRI for Preclinical Research
5:30-6:00 PM
Fabian M. Kiessling, MD: Characterization of Tumor Angiogenesis with Microstructural, Functional, and Molecular Imaging
Tuesday, June 11
8:00-9:30 AM
Intraoperative Imaging - West - 201
8:00-8:30 AM
Gooitzen M. Van Dam, MD, PhD: Expediting Translation of Optical Imaging into the Clinic
8:30-9:00 AM
Eva M. Sevick, PhD: Near-Infrared Fluorescence Imaging for Intraoperative Guidance and Surgical Pathology
9:00-9:30 AM
Fijs Van Leeuwen, PhD: Interventional Molecular Imaging of the Sentinel Node: A Hybrid Approach
12:30 - 2:00 PM
Emerging Technologies Session #4: Late Breaking Developments: Standardization, Funding Opportunities and Clinical Trials
(Non-CE Session) - West 306
12:30-1:00 PM
Thomas W. Armor: Radiotherapeutics and Imaging Using Small Molecules Targeting PSMA
1:00-1:30 PM
Antionio Sastre: Preparing a Competitive NIH Grant Application, and Other News from NIBIB
1:30-2:00 PM
Jeffrey T. Yap, PhD: The UPICT FDG PET/CT Protocol- Public Comment Session
2:45 PM-4:15 PM
Cerenkov Update - West - 201
2:45-3:15 PM
Jim Delikatny, PhD: Contrast Mechanisms in Cerenkov Imaging
3:15-3:45 PM
Jan Grimm, MD, PhD, ABNM: Cerenkov Images: Promises and Challenges
3:45-4:15PM
Brian Pogue, PhD: Cerenkov Emission Imaging in Radiation Therapy for In Vivo Dosimetry and Beam Verification
8:00 AM-9:30 AM
Road to Translation - Addressing the Challenges - West 202-204
8:00-8:30 AM
Lee Josephson, PhD: Barriers to Clinical Translation with Diagnostic Drugs
Wednesday, June 12
8:30-9:00 AM
Steve Y. Cho, MD: Clinical Translational Road Trip - Challenges and Opportunities in Nuclear Imaging
9:00-9:30 AM
Jonathan Sorger, PhD: Imaging Agent Prospects and the Challenges of Device Development
9:45-11:15 AM
Imaging for PET Probe Development from Idea to IND - West 205-207
9:45-10:15 AM
David Stout, PhD: Idea to IND for PET Probe Development
10:15-10:45 AM
James Thomas Secrest, MD: How Do They Conduct Imaging Work - Part I
10:45-11:15 AM
Mark Lane: How Do They Conduct Imaging Work - Part II
9
MI Gateway is a quarterly member information service published
under the direction of the Center for Molecular Imaging Innovation and
Translation leadership and SNMMI.
Editorial Board
PET/MR Primer. Continued from page 7.
undergone recent surgery.
In summary, PET/MR is a growing field that provides numerous
challenges, but with the volume of patients and research topics increasing,
working with this modality offers a great opportunity for learning and
career development for nuclear medicine technologists. It is an exciting
time for two different disciplines to merge and learn about one another.
PET/MR provides a wonderful tool that can be very advantageous for
clinical diagnostics and is already proving that it will improve patient
care. We are proud to be a part of a wonderful team and every day is a
new learning experience.
Kimberly Jackson and David Faul, PhD
Anthony Giamis, PhD
Scott Holbrook, BS, CNMT, FSNMMI-TS, Issue Editor
Nashwa Jarkas, PhD
Alexander L. Klibanov, PhD
Christopher Chad Quarles, PhD
Buck E. Rogers, PhD
Neil Vasdev, PhD
Lauren Woodard, PhD
CMIIT Board of Directors
Jeff Bulte, PhD
Frederic H. Fahey, DSc
Michael M. Graham, PhD, MD
Edward (Ted) Graves, PhD
Jan Grimm, MD, PhD
Peter Herscovitch, MD
Kimberly Kelly, PhD
Laura Norman, CNMT, PET
Buck Rogers, PhD
Andrew Tsourkas, PhD
John F. Valliant, PhD
Neil Vasdev, PhD
Board Intern:
Lauren Woodard, PhD
Non-Member Advisors
Calendar of Events
96th Canadian Chemistry Conference
and Exhibition
www.csc2013.ca
May 26-30, 2013
Québec City, Québec, Canada
SNMMI 2013 Annual Meeting
www.snmmi.org/am
June 8-12, 2013
Vancouver, British Columbia, Canada
Radiometals 2013
radiometals2013.triumf.ca
June 13-16, 2013
Santa Rosa, CA
Peter S. Conti, MD, PhD
Michael D. Devous, Sr., PhD
Timothy R. Degrado, PhD
Mehran Sadeghi, MD
SNMMI Chief Executive Officer
Virginia Pappas, CAE
Director of Leadership and SNMMI-TS Administrator
Nikki Wenzel-Lamb, MBA
Production Editor
Susan Martonik
Graphic Designer
Laura Mahoney
World Molecular Imaging Congress
www.wmicmeeting.org
September 18-21, 2013
Savannah, GA
SNMMI 2014 Mid-Winter Meeting
www.snmmi.org/mwm2014g
February 6-9, 2014
Palm Springs, CA
1850 Samuel Morse Drive
Reston, VA 20190
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