Download 3D Cardiac Imaging

4/16/2013
3D Cardiac Imaging
Raja Muthupillai, PhD
Department of Diagnostic and Interventional Radiology
St. Luke’s Episcopal Hospital
Houston TX
Houston,
Disclosures
• Research Support: Philips Healthcare
This presentation contains information regarding
the use of Gadolinium based CA which is not
FDA approved for CV imaging
1
4/16/2013
2D Imaging Versus 3D Imaging
ky
ky
kz
kx
kx
3D Cardiac Imaging : Why?
Scan Time
SNR/voxel
Typical Slice Thk
Blood-Muscle CNR
2D-Imaging
3D-Imaging
Ny x N x TR
Ny x N x TR x Nz
Ny
> 3 mm
< 1 mm (possible)
High (Inflow effect)
FoVsl Dependent
2
4/16/2013
3D Cardiac Imaging
Morphologic Imaging
Functional Imaging
Large Coverage
Rapid Imaging
High Spatial
Resolution
High Temporal
Resolution
Volumetric Cine
Coronary MRA
Diastolic Function
Systolic Function
Outline
• A systematic approach toward a coronary
MRA protocoll
• Two common approaches for cMRA
• Typical Problems and Solutions
3
4/16/2013
Coronary MRA: Requirements
• Small
High Resolution (< mm)
• Tortuous
Large Coverage
• Motion
Gating (Cardiac/Respiratory)
• Coronary Flow
Acq. Duration
• Epicardial Fat
Blood to Fat Contrast
• Muscle
Blood to Muscle Contrast
Goals of Coronary MRA
 Extend Acquisition Time
 Maximize Blood (Arterial) Contrast
4
4/16/2013
Breath-holding?
Multiple Breathholds?
• BH duration: 16-22 heartbeats
Posittion of diaphragm
I. Respiratory Motion and cMRA
• Acq. Duration: 2200 - 3000 ms
• Num PEs : 550-750 (TR=4 ms)
• One or two high resolution slices /
breath hold
BH1BH2
BHn
Pencil-Beam Respiratory Motion Tracking
RF
• Freely Movable
• Low Flip Angle
excitation
G1
• Real time
tracking
G2
A(z)
end-inspiration
end
inspiration
end-expiration
z
5
4/16/2013
Livver
Lung
Real-Time Respiratory Tracking/Gating :
Accept /Reacquire Algorithm
Time 
Navigators extend Acquisition time beyond breathholding capacity
II. Contrast Preparation for cMRA
• Epicardial Fat
1
0.9
– Fat
F SSuppression
i
0.8
0.7
• Arterial Blood
0.6
Arterial Blood
0.5
xy
0
M /M a.u->
• Cardiac Muscle
0.4
0.3
02
0.2
• Venous Blood
Cardiac Muscle
0.1
0
Venous Blood
0
50
100
150
200
250
T Prep Duration (msec)
2
6
4/16/2013
Effect of T2 Preparation:
0.7
Sig
gnal Difference (a.u)->
0.6
Art-Ven
0.5
Art-Mus
0.4
0.3
02
0.2
0.1
0
0
50
100
150
200
T Prep Duration (msec)
250
2
Typical cMRA Protocol
Nav Track
50 ms
30 ms 15 ms
75 ms
T2 prep
NAV Fat Sat
3-D TFE /
SSFP
7
4/16/2013
Targeted cMRA protocol
Aarhus
Berlin
Boston
Leiden
N = 109
AO
Single Vendor
LCA
LV
Sub Lingual
ISDN
RCA
Cologne
St. Luke’s
Leeds
Zürich
Prevalence of disease by > 50% diameter
invasive angiography
stenosis (%)
Overall
%
LM
LAD
59
Left Main
5
Left anterior descending
28
Left circumflex
23
Right coronary
36
One – vessel disease
28
Two – vessel disease
18
Three – vessel disease
12
LCx
RCA
Any
LM / 3 VD
Sensitivity
67
88
53
93
93
100
Specificity
90
52
70
72
42
85
Prevalence
89
65
67
80
43
15
PPV
30
56
29
69
70
54
NPV
98
86
86
94
81
100
Kim et al. NEJM, 2001
8
4/16/2013
Whole Heart 3D cMRA
• Similar to prior cMRA
• SSFP readout
• In-plane resolution
1.0 mm x 1.0 mm
• SENSE factor x 2
CB Higgins et al. MRM 2003;50:1223-1228
Sakuma, et al. JACC, 2006
Sakuma et al. :
n = 131 pts; Scan Time: 12.9 ± 4.3 min (5.8 – 28.8 min)
86% Completion rate; Mean weight: 65 kg
9
4/16/2013
Advances in Whole Heart SSFP cMRA
 1.5 T scanner; 32 Channel coil
 SENSE factor 2 x 2
 Voxel 1 x 1 x 1.5 mm
 Magnetization prepared, fat – sat
3-D SSFP
 Mean scan time 240 ± 40 secs
K Nehrke et al. JMRI 2006;23:752-756
Whole Heart coronary MRA
32 Channel coil/SENSE factor 4;
Scan Time: 5 min @ 70% efficiency
Courtesy: Dr. Benjamin Cheong, SLEH.
10
4/16/2013
Clinical Applications : Coronary MRA
A
3
Ao
LA
Tissue Characterization
Proximal Coronaries
Coronary Anomalies
Typical Problems and Solutions
 Significant Motion
artifacts in Image
Check if Data Acquisition is
at correct cardiac pphase
Displacement mm/1000 ms
15
RCA
10
5
LAD
0
0
200
400
600
Trigger Delay
800
Sodickson, et al, ISMRM 1997
 Acquire a High Temporal
Resolution Cine to select
Appropriate cardiac phase
11
4/16/2013
Typical Problems and Solutions
 Patient Falls asleep, and
Breathing position has changed
 Enable Navigator Drift
Correction ((if available))
 Speed up Acquisition
(Use Parallel Imaging)
w/o SENSE: 850 hb
with SENSE: 400 hb
Typical Problems and Solutions
Navigator efficiency too low
 Enable Motion Adapted
( available))
Gatingg (if
Muthupillai, et al. AJR, 2006
 Restrict coverage/Use
SENSE
with SENSE: 410 hb
with SENSE+MAG: 360 hb
12
4/16/2013
Typical Problems and Solutions
 Coronary MRA at 3.0T
 Use TFE readout versus SSFP
Sensitive to off-resonance;
Long TR due to spatial res demands
 T2 prep less robust; IR-prep
post-contrast
Stuber et al. MRM 2002
13
4/16/2013
Thank you!
14