Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Tuesday, July 28, 2009
Imaging Continuing Education Course
Outline
CE-Imaging: Multimodality Medical Imaging - I
Multimodality Imaging – Clinical
Perspective
Michael W. Vannier, M.D.
University of Chicago
• Challenges in diagnostic imaging technology
(2009)
–Multimodality – What, why, how?
–Applications
• Identify trends
–New scanners and applications
–Low end CT scanners:
• Point of Care CT ; DentoMaxilloFacial/ENT;
Portable CT
8/3/2009
2
Case History
46 year old female with melanoma.
PET-CT exam for initial staging.
AAPM 2008 Michael W. Vannier University of Chicago
Radiological Presentations
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Radiological Presentations
Multimodality, multitemporal
imaging
• Payors will reimburse for a single exam
from a single modality (pre-cert) at a single
time – for diagnosis/staging
• Follow-up scans to evaluate disease
status (e.g., restaging; response
evaluation)
• Common scenario:
– Detect lesion on CT, and characterize it with
MRI. Biopsy with US.
Case History
Liver Mass
65 year old male with elevated liver
function tests.
US
Status post sigmoidectomy for colon
cancer 5 years ago.
CT exam to rule out mass or biliary
tract disease.
CE MDCT
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
MRI of liver
T2w
T2-fatsat
Liver hemangioma
T1-in phase
T1-out of phase
• Hepatic hemangiomas are present in
about 7% of healthy people.
• Hemangiomas are four to six times
more common in women than in men.
• Hemangiomas, although referred to as
tumors, are not malignant and do not
become cancerous.
• Hemangiomas are not unique to the
liver and can occur almost anywhere in
the body.
Pre-
DCE = dynamic contrast enhancement
Post-
Why so many modalities?
•
•
•
•
Each has strengths and weaknesses; Synergy
One size / type does not fit all
Reimbursement; instrument/operator availability
CT is most available and widely used
– Essential technology for emergency dept.
– CT is fast; 24/7 access
• MR is expensive, time consuming
– Some patients are ineligible or unable to tolerate
• US is operator dependent
– Skilled examiner is required, otherwise many errors
– Real time; versatile; safe; widely available
AAPM 2008 Michael W. Vannier University of Chicago
• Giant hemangiomas do occur and are
susceptible to occult bleeding
Tools ~ Modalities
•
•
•
•
Use the right tool for the job
No single tool will suffice
One size doesn’t fit all
May be used separately or in
combination
• Some require a skilled
operator; others are simple
enough for anyone to use
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
When is multimodality imaging used?
When is multimodality imaging NOT
used?
• Breast imaging: mammography, ultrasound, MRI
• Cardiac imaging: echo, SPECT, cardiac cath,
CCTA, CMRI
• Prostate imaging: US, MRI, CT (for staging)
• Brain tumors: MRI, MRS, CT
• Stroke: CT (CTA and perfusion), MRI
• Solid tumors: CT, MRI, PET
• Transplant: US, MRI, CT
• Interventional: fluoroscopy, US, CT, MRI
• Orthopedic: radiography, MRI, fluoroscopy, CT
• Emergency: CT
• ICU: radiography (sometimes head CT or portable
US)
• O.R.: fluoroscopy (sometimes US or radiography)
• Thyroid: US (and sometimes SPECT)
• Follow-up solid tumor/surveillance: CT
• And many others….
8/3/2009
8/3/2009
• And many others….
13
Choice of modality and scanning protocol is
difficult and complex.
• Limited knowledge of the clinical status and history
• Similar history may require very different exams:
– Abdominal pain
•
•
•
•
•
CT
– Altered mental status
• Prior surgery
• Known malignancy
• Intoxicated?
– Search for primary tumor – occult malignancy
Exceptions
r
ho
W it out IV
h
wit trast ?
? con
Depends on renal function and allergy to iodinated contrast
Acute vs. chronic; where does it hurt?
WBC; fever
Ora
Jaundice
l co
ntra
Gender and gynecologic history
• Diversity of patients;
generalizations are difficult
MRI ?
US ?
st ?
ler ?
Dopp
PET ?
De
l
ima ayed
ges
?
• Payor may deny reimbursement for repeat or additional exams.
• Serum biomarkers
• Known metastases
15
AAPM 2008 Michael W. Vannier University of Chicago
14
– Massive obesity
– Children (including neonates and infants)
– ICU patients – on respirator
– Immunosuppressed; contagious (e.g., Tb)
– Mental impairment; claustrophobia
– Pregnancy
– Renal failure – acute and chronic
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Multitemporal imaging
• Contrast-enhanced: (within exam session)
– Multiphase: arterial, venous, equilibrium
– Perfusion: DCE
– 10+ minute: excretion; redistribution
• Sequential
(e.g., monthly, quarterly encounters)
– Restaging in oncology; Baseline + followup
– Revascularization; vessel patency
– Measure of response to therapy
Multiphase contrast-enhanced
imaging
• Common in CT and MRI
• Essential for liver, pancreas, kidneys
• CT angiography typically consists of both
a non-contrast and post-contrast
enhanced series (same for MRA)
• Multiphase cardiac CTA:
– Precontrast coronary calcium scan
– Post-contrast retrospective gating
• e.g, Imaging biomarker
Multiphase CT
Liver lesion after RFA
Cardiac imaging – an example
• EKG and stress testing cardiac SPECT
• Abnormal SPECT cardiac cath & PCI
or may choose coronary CTA
• Coronary calcium measurement with CT
Pre-
– Risk assessment by age and gender norms
• Valvular disease: echocardiography
• Cardiac MRI
– Congenital anomalies, congenital heart disease
– Myocardial viability; cardiac function
Post-
Future? – PET-CT; MRI-PET; …
Same slice, multiple time points
Liver malignancy prior to RFA
AAPM 2008 Michael W. Vannier University of Chicago
Modalities
SPECT
Cath / PCI
CCTA
CorCa CT
Echo
CMRI
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Delayed CT/MRI imaging
• Redistribution phenomena
Cardiac Imaging Modalities (CT; MRI, echo)
– Gd contrast into fibrosis (Myocardial viability)
– Cholangiocarcinoma (malignant)
– Adrenal adenoma (benign)
– Hemangioma (benign, but may be very large)
• Renal excretion
– Antegrade opacification of urinary tract
– Basis of CT urogram (akin to IVP / EXU)
http://journals.tums.ac.ir
AAPM 2008 Michael W. Vannier University of Chicago
http://journals.tums.ac.ir
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Myocardial SPECT
Stunned Myocardium
brighamrad.harvard.edu/education/online/Cardiac/
www.gehealthcare.com/euen/advantage-workstation/
Integration of the
multislice PET
scanner into a 7-T
MRI apparatus.
Simultaneous PET-MRI: a new
approach for functional and
morphological imaging
Martin S Judenhofer, et al.
Nature Medicine 14, 459 - 465 (2008)
AAPM 2008 Michael W. Vannier University of Chicago
26
PET/MRI scan of a tumor in a lab mouse. The
arrow points to central necrosis within the tumor.
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
CT Market Doldrums
Average
selling price
($million)
29
Four major manufacturers
3 major types – 16, 64, high-end
MSCT time table – The applications of CT change
as the technology advances
Applications of MDCT
•MPR and CTA
as routine.
•Colon
•Brain Perfusion
Cardiac CTA
•Temporal
Resolution and
coverage race
•MPR
•CTA
Colon
•Volume
Rendering well
accepted
•Cardiac CTA as
routine in some
centers
•Whole Organ
coverage
•Dynamic
Study
Perfusion and
Function
Whole head
CT perfusion;
Whole thorax
coverage
•Gated Studies
•Organ
Perfusion
•CT
Fluoro
•CA SC
+CTA
•MPR
CTA
CA
SC
•As Low As Reasonable Achievable ALARA
2009
www.klasresearch.com
AAPM 2008 Michael W. Vannier University of Chicago
•1998
•2000
•2002
•2004
•2006
•4 Slice CT
•8 /16 Slice CT
•32 /40 Slice CT
•64 Slice CT
•Dual Source CT
MDCT area coverage (# slices)
•2007
Wide Area Detector CT
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
http://www.pedrad.org/associations/5364/ig/
33
13 yr old Female- Scanned w/256-slice CT
Clarity™ Tissue Adaptation
An Imaging Services Company
Clarity in Imaging
• Automatically adapts to the tissue.
• Decrease noise in the soft tissue and increase the contrast in the lung.
original
• 4.8 sec scan
processed
• 2D AntiAnti-Scatter
detector grid improves
contrast resolution
• Smart Focal Spot for
artifact elimination
processed
original
35
Clarity™ Solution
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Pediatric - Liver
An Imaging Services Company
Obese patient - Liver
An Imaging Services Company
Clarity in Imaging
processed
original
Clarity in Imaging
original
processed
Thin slice 0.6 mm
Clarity™ Solution
Clarity™ CT Solution Server
•
An Imaging Services Company
Clarity™ Solution
Clarity™ Ultra Low Dose CT Liver
An Imaging Services Company
Clarity in Imaging
Clarity in Imaging
Clarity™ CT Solution Server acts as a DICOM node that receives DICOM3.0 compliant data,
then processes the data, and then forwards the optimized study to the selected destination. This
destination can be any DICOM node, typically either the PACS system or a specific workstation.
Original / Processed
PACS
DICOM Network
Clarity™ CT Solution – Server
Workstation
Standard Desktop Computer Solution
CT Source(s)
DICOM
Destination(s)
Clarity™ Solution
AAPM 2008 Michael W. Vannier University of Chicago
100 %
(standard dose)
50 %
(low dose)
50 % dose
(processed)
Clarity™ Solution
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Multirow Detector CT (MDCT) Scanner
128 detector rows; 256 slices (iCT)
Increased Speed, Power, Coverage
• Higher temporal resolution
– 0.27 sec rotation
• Increased Tube Power
– 120 kW / 1,000 mA
– X-Y and Z focal spot modulation
• Greater coverage per rotation
• 8 cm
• 256 slices
41
Nose to Toe Scan:168 cm in 22sec
AAPM 2008 Michael W. Vannier University of Chicago
Multi-phase Cardiac
Imaging less than 5 sec
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
40-64 channels
256 channels
320 channels
256-320 detector row CT scanners
Enables 4D CT angiography &
Whole organ perfusion exam
Non-Gated
Chest CT Scan
Large Patient Cardiac CT
Excellent coronary visualization
132kg
162cm
50 BMI
52 bpm
RT=0.33sec
BMI = 50
47
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Head & Neck
CT Brain Perfusion
MRI of Cerebral Ischemia
Early DWI/MTT mismatch, lesion growth
FSE T2W
Initial DWI
Initial MTT
DWI 5 days later
78 yo female 3 hrs after onset of aphasia during cardiac cath.
8/3/2009
51
Greg Sorensen, Massachusetts General Hospital
AAPM 2008 Michael W. Vannier University of Chicago
8/3/2009
52
Bernhard Preim, Visualization Research Group, University of Magdeburg, Germany
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Perfusion
CTP
T2
DWI
MRP
MTT
STROKE
IMAGING
Non-contrast CT
CT vs. MRI
MRI
vs. xenon CT vs. PET vs. SPECT
8/3/2009
53
8/3/2009
54
Megan Strother, M.D., Vanderbilt University
Imaging Ischemia--Vascular
Megan Strother, M.D., Vanderbilt University
Imaging Ischemia- Parenchyma
Angiogram
1950-60’s (pre-CT era)
Head CT
Vascular occlusion
<1/3 MCA
territory
No ICH
24 hours
Thrombolysis
<3 hours
Recanalization =
Clinical improvement
8/3/2009
IV Thrombolysis
55
Megan Strother, M.D., Vanderbilt University
AAPM 2008 Michael W. Vannier University of Chicago
8/3/2009
56
Megan Strother, M.D., Vanderbilt University
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
MR
vs. CT
A
d
v
a
n
t
a
g
e
Wall Clock
Vascular Occlusion
Parenchymal changes
on non-contrast CT
CT
MR
Tissue Clock
CBF
MTT
CBV
• No radiation
• Better contrast
.
8/3/2009
57
M
R 58
8/3/2009
Megan Strother, M.D., Vanderbilt University
A
d
v
a
n
t
a
g
e
CT
MR
• Diffusion = Infarct
• MR = 94% sensitive and 96%
specific for infarct
• Non-contrast CT = 50%
accurate for acute infarct
M
R 59
8/3/2009
Megan Strother, M.D., Vanderbilt University
AAPM 2008 Michael W. Vannier University of Chicago
Megan Strother, M.D., Vanderbilt University
CT
MR
• MR = whole-brain coverage
• CT limited by scanner (10-40 mm max)
• Post fossa obscured on CT by beamhardening artifact
8/3/2009
A
d
v
a
n
t
a
g
e
M
R 60
Megan Strother, M.D., Vanderbilt University
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
A
d
v
a
n
t
a
g
e
MR
CT
• Speed
• Accessibility
• Spatial Resolution on CTA
C
T
8/3/2009
A
d
v
a
n
t
a
g
e
MR
CT
– Quantifiable
• MR relies on indirect T2* effects on tissue
from gad, therefore not quantifiable
61
8/3/2009
Megan Strother, M.D., Vanderbilt University
C
T
62
Megan Strother, M.D., Vanderbilt University
CT Scan
Protocol
1st
Non-contrast
Head CT
quantifiable
whole-brain coverage
CTA vascular detail
accessible
2nd
no radiation
cheap
STROKE
IMAGING
CT Perfusion
diffusion
fast
CTP
MRP
8/3/2009
3rd
63
Megan Strother, M.D., Vanderbilt University
AAPM 2008 Michael W. Vannier University of Chicago
8/3/2009
CT angiogram
64
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Head & Neck
8/3/2009
65
CT Scanning Protocol – 320 Channel
Whole Head Dynamic CTA (Multiple Phases) (16 cm z-axis coverage)
Multitemporal acquisition protocol
Subtracted wholewhole-brain dynamic CTA
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Whole Brain Perfusion (16 cm z-coverage)
Whole Brain Perfusion
ROIs
Axial Views
Multitemporal acquisition protocol
Workflow for whole brain
CT perfusion exam and
postprocessing…
3D View
(Interactive)
Coronal Views
Spectral and Dual Energy CT
Simple Analogy
71
AAPM 2008 Michael W. Vannier University of Chicago
Traditional
CT
Spectral
CT
Limited Spectral
CT
Dual Energy
CT
Yesterday & Today
Future
Future
Today
CT Clinical Science, 24 April 2009
72
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Dual-energy Material Separation
Separation line
HU of E1
Iodine
X-ray Detector
signals
Iodine > Calcium
Calcium
Iodine < Calcium
H2 O
Attenuation [a.u.]
HU of E2
10
0
Calcium
10
-1
X-ray tube
spectrum
10
-2
20
40
Iodine
solution
E1
60
CT Clinical Science, 24 April 2009
E2
kv
80
100
120
140
73
Siemens
Spectral vs. Dual Energy CT
Spectral vs. Dual Energy CT
Techniques That are Possible on Commercial Systems
Techniques That are Available on Research Systems
Dual Source
Dual kV Switch
Dual Spin
Not Spectral CT
Dual-layer (“Double Decker”) Detector*
Photon Counting*
*Works-in-Progress: Pending commercial availability and regulatory clearance
CT Clinical Science, 24 April 2009
AAPM 2008 Michael W. Vannier University of Chicago
75
CT Clinical Science, 24 April 2009
76
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Dual-Layer CT (Orion-N)
Spectral CT
How does spectral CT fit into today’s standard of care?
~50%
E1 image
+
High Energy Raw data
• No medical guidelines include spectral CT
• No reimbursement for spectral CT
E2 image
• No large studies have been published for
spectral CT
---------------------------------------
=
• Alternative approaches exist for proposed
spectral CT clinical applications
Weighted combined Raw data CT image
• Rapidly changing technology
CT Clinical Science, 24 April 2009
77
CTA Bone removal
SCINT2
Low Energy Raw data
Cardiac perfusion
Double-Decker Diode
~50%
SCINT1
Lung perfusion
100%
Conventional CT
CTA Bone removal
Photons
Dual Energy CT
Cardiac perfusion
X-Rays
Lung perfusion
“new clinical features, such as
spectral imaging, may still be
works in progress through 2010
and longer”
CT Clinical Science, 24 April 2009
78
CONE BEAM CT
/7
80
79
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Advantages in Dental Imaging
•
•
•
•
•
CBCT vs. Panoramic
Lower dose than helical CT
Compact design
Superior images to Panoramic
Low cost
Low heat load
Cephalometric
CBCT image
Cephalometric
Panoramic image
Dose:
Panoramic: 6-20 µSv
CBCT: 20-70 µSv
Conventional
CT: 314 µSv
/7
/7
The i-Cat CBCT
82
Shortcomings
•
•
•
•
Metal artifacts?
Worse low contrast detectability
Long scan times = motion artifacts
Slightly Inferior quality to conventional CT
/7
CBCT
Periodontal ligament spaces easily recognizable in the dental CT
but not satisfactory in the CBCT
AAPM 2008 Michael W. Vannier University of Chicago
8/3/2009
84
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Dentomaxillofacial Images
Sagittal MPR
8/3/2009
8/3/2009
Panoramic
85
86
8-Slice Portable CT Scanner
8/3/2009
8/3/2009
87
AAPM 2008 Michael W. Vannier University of Chicago
88
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Radiation Data
Low X-Ray Radiation Dose
Sinus CT with a full-body scanner
• Adult: 1.0-2.0 mSv
• Child: 1.0-2.0 mSv
Sinus CT with the MiniCAT™ low-dose scanner
• Adult: 0.13 mSv (7-15 x lower radiation dose)
• Child: 0.07 mSv (14-28 x lower radiation dose)
8/3/2009
89
90
Another Clinical Example….
This is the same pt
scanned within 24
hours using the
Ceretom portable
scanner and then a
GE stationary
scanner…
Ceretom
8/3/2009
Patient
500lb 38 year old
African American
male
GE
Symptoms
Aphasia and right
sided hemiparesis.
Issues
Unable to scan a
patient over 450lbs.
Patient went 5 days
without a CT scan.
Which
do you
prefer?
Imaging
Large MCA infarct
with mass effect &
midline shift.
Ceretom
GE
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Cerebrovascular Evaluation
CBF
CBV
CTA
Direct coronal imaging
Direct coronals
MTT
CT Perfusion (CTP)
•axial, 1 cm slice, 1 slice/second,
•acquisition time is user defined (30-40 seconds)
•reconstruction on the scanner in real time
Direct Coronal Facial CT
4 months apart, same Pt, same dose, same recon settings
8/3/2009
CereTom
GE Lightspeed
96
AAPM 2008 Michael W. Vannier University of Chicago
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Use of multimodality and
multitemporal data
Enterprise Visualization
• Post-processing software tools
– Visualization: MPR and 3D
– Fusion: usually limited to image pairs
– Perfusion: based on assumed
compartmental model, not standardized
– Most interpretations are subjective
• Enterprise integration with PACS
– Access to images and advanced
analysis tools remotely
– Subspecialized experts apply unique
tools for planning, implant specification,
response measurement
Medical Imaging Workstations
Should we offer
advanced
visualization
services across
the enterprise
using a clientserver system?
Thin Client Solutions
Why
What
Where
•Time is a
physician’s most
precious asset
•Images
•“Every 15-seconds
matters”
•All Key
Applications
•Scanner
•Workstation
•PACS
•Virtual Private Network
•Department
•Hospital
•Imaging Center
•Home
•3D Viewing
8/3/2009
Thick Client – expensive, with substantial
8/3/2009
local processing capability
Thin Client – small, portable
99
Accessible throughout enterprise
AAPM 2008 Michael W. Vannier University of Chicago
100
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
Revolution in thin-client solutions
Thin Client Solutions
Adding applications and 3D to viewing
CT viewing plus
• Comprehensive Cardiac Analysis
PACS
• Brain perfusion-summary maps
Tech
at scanner
• CT Angiography Applications
- AVA Stenosis and Stent Planning
Department Workstations
CT Scan
Room
CT Control
Room
• Lung Nodule Assessment
Workspace
Portal
All
Key
Clinical
Applications
• Virtual Colonography
Cath or EP Lab
3D Tech
at Workstation
8/3/2009
3D Lab
Anywhere
using WAN
8/3/2009
Home
101
102
Conclusion
Acknowledgments
• Multimodality (and multitemporal) imaging is
widely used
• Tailoring systems to solve specific diagnostic
imaging problems is complex
• Workflow includes post-processing on imaging
workstations, distributed across the clinical
enterprise
• New scanners and technologies are emerging –
wide area CT, dual energy, cone beam OMF
scanners, portable CT, PET/MRI
8/3/2009
AAPM 2008 Michael W. Vannier University of Chicago
103
•
•
•
•
•
•
•
•
•
•
•
John Steidley, Ph.D., Philips Medical Systems
GE Healthcare, Inc.
Siemens Medical Solutions, Inc.
Diego Ruiz, Johns Hopkins Hospital
Predrag (“Pedja”) Sukovic, Xoran Technologies, Inc.
Bernhard Preim, University of Magdeburg, Germany
John C. Messenger, MD, FACC, University of Colorado
Megan Strother, MD, Vanderbilt University
Patrik Rogalla, MD, Charite’ Berlin
Alisa Gean, MD, UCSF Radiology
David Rosenblum, DO, Case Western Reserve Univ.
8/3/2009
104
Multimodality Imaging - Clinical
PerspectiveAAPM 2007 - Multimodality
Medical Imaging - I
AAPM 2008 Michael W. Vannier University of Chicago