cardiac mri at 3 - afni.nimh.nih.gov...cardiac mri: 3.0t paul finn, md david geffen school of...

1ISMRM 2006

Cardiac MRI: 3.0TCardiac MRI: 3.0T

Paul Finn, MD

David Geffen School of Medicine at UCLA

AcknowledgementsAcknowledgements

Stefan Ruehm, MD

Kambiz Nael, MD

Roya Saleh, MD

Anthony Ton, MD

Mayil Krishnam, MD

Sergio Godines, RT

Glen Nyborg, RT

Howard Dinh,MD

Carissa Fonseca, Ph

Gerhard Laub, PhD

Vibhas Deshpande, PhD

Hanns Weinmann, PhD

3 Tesla: Advantages3 Tesla: Advantages

SNR

[ T ]1.5 3.0

T1

Field Strength

SNR x 2SNR x 2SNR x 2

2ISMRM 2006

3 Tesla: Disadvantages3 Tesla: Disadvantages

SAR

1.5 3.0

SAR x 4SAR x 4SAR x 4

[ T ]

Field Strength

Cardiac MRI at 3.0TCardiac MRI at 3.0T

Why?

Needs to compete favorably with cardiac MRI at 1.5T

Tim Trio Tim AvantoTim Trio Tim Avanto

3T 1.5T45 mT/SR200 45 mT/SR20050 cm 50 cmTim Tim

3T 1.5T45 mT/SR200 45 mT/SR20050 cm 50 cmTim Tim

3ISMRM 2006

Cardiac Cine MRI at 1.5T*Breath-hold Segmented SSFP Cine

Cardiac Cine MRI at 1.5T*Breath-hold Segmented SSFP Cine

* Carr JC, et al. Radiology 2001;219:828-834.

Segmented TrueFISP Cine: 1.5T

General Trends at 3.0T vs 1.5TGeneral Trends at 3.0T vs 1.5T

4ISMRM 2006

Increased SARIncreased SAR

Limits flip angles and minimum TR for high-performance sequences

SSFP cine

Spin echo train imaging

CEMRA

Increased SNRIncreased SNR

Potential benefits for techniques which have borderline SNR

Perfusion imaging

Viability imaging with delayed enhancement

Coronary imaging

B1 InhomogeneityB1 Inhomogeneity

Shading in some regions

Inhomogeneous contrast in some regions

May make calibration of RF transmitter voltages difficult –varying flip angles within body regions

5ISMRM 2006

B1-InhomogeneityB1-Inhomogeneity

Increased sensitivity to flow-induced noise on ECG trace can make gating more problematic

Magneto-hydrodynamic effectMagneto-hydrodynamic effect

Cine MRI at 3.0T vs 1.5TCine MRI at 3.0T vs 1.5T

SSFP now the standard at 1.5T

TrueFISP

FIESTA

Balanced FFE

At 3.0T, SSFP cine is challenging

6ISMRM 2006

Cine MRI at 3.0T vs 1.5TCine MRI at 3.0T vs 1.5T

Ideal conditions for TrueFISP cine

TR as short as possible

Flip angle high and uniform

Very homogeneous magnetic field

At 3.0T, all of these conditions are violated due to a combination of SAR, patient-induced susceptibility gradients and dielectric resonance effects

3T Functional Cardiac ImagingSSFP cine: off-resonance artifact

α = 30 degα = 50 deg

SAR-Limitations:Effects on TrueFISP cine

SAR-Limitations:Effects on TrueFISP cine

lower CNR

7ISMRM 2006

Dark-blood Imaging @ 3T: long „TR“Dark-blood Imaging @ 3T: long „TR“

db-HASTE db - TSE

Cardiac Function @ 3TCardiac Function @ 3T

FLASH, 20°TrueFISP, 40°

• Use longer RF pulses than at 1.5T• flip angle around 30° - 40° (less signal and contrast)

Cardiac TrueFISP imaging at 3TCardiac TrueFISP imaging at 3T

8-channel cardiac array coil

with PAT x2 TA 8 sec

8ISMRM 2006

Parallel Imaging @ 3TParallel Imaging @ 3T

15 sec 8 secwith iPAT x2without iPAT

TrueFISP short axis

Temporal resolution 25 msecMatrix: 256x256

Cine TrueFISP iPAT x24 slices in 12 sec 3.5 x 2.8 x 8 mm

Temporal resolution = 25 ms

Cardiac Function @ 3TCardiac Function @ 3T

TaggingTagging

Longer T1 @ 3T keeps tags visible longer

9ISMRM 2006

Functional MRI @ 3T(LVH)

Functional MRI @ 3T(LVH)

TrueFISP cine grid tagging

But: With TrueFISP Cardiac Tagging at 1.5TBut: With TrueFISP Cardiac Tagging at 1.5T

1.0mm x 1.5mm x 6 mm voxels30 msec temporal resolution

7 second acquisition

Better persistance of tags than with SGRE

Cardiac Function @ 3TCardiac Function @ 3T

Cine TrueFISP

courtesy of Dr. Miller, University of Tuebingen

10ISMRM 2006

Cardiac Function @ 3TCardiac Function @ 3T

Cine TrueFISP

courtesy of Dr. Miller, University of Tuebingen

Current status of Cine MRI at 3.0T vs 1.5TCurrent status of Cine MRI at 3.0T vs 1.5T

SSFP cine at 3.0T is more sensitive to off-resonance effects than at 1.5T

Can be ‘managed’ by attention to shim status and by adjusting frequency offsets on a slice-orientation basis

In an individual case, may work; or may not

Contrast Enhancement in InfarctionContrast Enhancement in Infarction

Ex-vivo comparison of TTC and Gd-enhanced MRI in infarcted myocardium

TTC MRI

courtesy of Dr. R. Judd, Northwestern University, Chicago

11ISMRM 2006

Evaluation of Viability and Myocardial Perfusionwith IV contrast

Note: Gd is not FDA approved for cardiac imaging

Evaluation of Viability and Myocardial Perfusionwith IV contrast

Note: Gd is not FDA approved for cardiac imaging

time

Normal MyocardiumInfarcted Myocardium

Ischemic butViable Myocardium

First-Pass Delayed Enhancement

Gadoliniumcontrastinjection

Left Circumflex distribution infarction: 1.5TLeft Circumflex distribution infarction: 1.5T

Segmented TrueFISP: Cine and Viability @ 1.5TNon-Ischemic Cardiomyopathy

Segmented TrueFISP: Cine and Viability @ 1.5TNon-Ischemic Cardiomyopathy

IR TrueFISP: 64 lines / heart beat

12ISMRM 2006

Viability @ 3T

IR single shot TrueFISPCourtesy of Dr Regenfuss, University of Erlangen

Viability & Function @ 3TViability & Function @ 3T

IR single shotTrueFISP

Cine TrueFISP

Viability & Function @ 3TViability & Function @ 3T

IR TurboFLASH

Cine TrueFISP

courtesy of Dr. Miller, University of Tuebingen

13ISMRM 2006

Lt Cx Infarction: 1.5TLt Cx Infarction: 1.5T

Lt Cx Infarction cine: 3.0T vs 1.5TLt Cx Infarction cine: 3.0T vs 1.5T

Lt Cx Infarction: ViabilityLt Cx Infarction: Viability

3.0TVS

1.5T

14ISMRM 2006

Perfusion @ 3TPerfusion @ 3T

SR single shot TurboflashFirst passiPAT x24 slices/heartbeat

Courtesy of Dr Regenfuss, University of Erlangen

First-Pass Imaging at 3.0TTurboFLASH + iPAT

First-Pass Imaging at 3.0TTurboFLASH + iPAT

Optimized Saturation Recovery Pulse forReduced B1 Sensitivity

Northwestern University, Chicago

Adenocarcinoma RVOT: 3.0TAdenocarcinoma RVOT: 3.0T

15ISMRM 2006

32 channel Tim Trio: 32 channel Tim Avanto32 channel Tim Trio: 32 channel Tim Avanto

3T 1.5T45 mT/SR200 45 mT/SR20050 cm 50 cmTim Tim

3T 1.5T45 mT/SR200 45 mT/SR20050 cm 50 cmTim Tim

Cardiac MRI at 3.0T: Pre-RF AblationCardiac MRI at 3.0T: Pre-RF Ablation

SSFP CINE

Delayed Contrast enhancement Viability Imaging

Cardiac MRI at 3.0T: Pre-RF AblationCardiac MRI at 3.0T: Pre-RF Ablation

16ISMRM 2006

Pulmonary Vein Anatomy

500 mm FOV 576 matrix

Cardiac MRI at 3.0T: Pre-RF AblationCardiac MRI at 3.0T: Pre-RF Ablation

Pulmonary Vein Anatomy

500 mm FOV 576 matrix Volume rendering

Cardiac MRI at 3.0T: Pre-RF AblationCardiac MRI at 3.0T: Pre-RF Ablation

Coronary MRA @ 3TCoronary MRA @ 3T

LADRCA

Breath-held 3T TrueFISP Coronary MRA

Courtesy Vibhas Deshpande, PhD, UCLA

17ISMRM 2006

Coronary MRA @ 3TCoronary MRA @ 3T

3T TrueFISP Coronary MR Angiography(breath-hold, 28 heart beats)

UCLA

LADLAD

Coronary MRA @ 3T Coronary MRA @ 3T

TA: 6:27 minPixelsize: 0.9 x 0.9 x 1.2 mm

8-channel cardiac array

Active electrode ECG triggering

1D PACE for motion correction

3.0T1.5T

Coronary MRAContrast-enhanced FLASH

X. Bi, D. Li. Northwestern UniversityCourtesy of Drs X Bi, D Li , Northwestern University, Chicago.

18ISMRM 2006

LMLM

AOAO

LADLAD

0.6 x 0.6 x 3mm voxel size

3T Coronary MRA in-vivo & in humans

3T Coronary MRA: ResultsCourtesy Matthias Stuber, PhD. Johns Hopkins University

RCARCA

LVLVRVRV

AOAO

PAPA LCXLCX

But: Coronary CT Angiography!But: Coronary CT Angiography!

R.F. 3532862

Right Heart FailureRight Heart Failure

19ISMRM 2006

TIM Trio: Thorax - dissection

TIM Trio: Thorax - dissection

6ml Gd, 12 measurements each 1.7 s apart21 s breath hold: iPAT x 3

Rest (R)Stress +

Stenosis (SS) SS - R

Myocardial BOLD Imaging at 3TMyocardial BOLD Imaging at 3T

Shea, D Li. Northwestern University, Chicago, Illinois.

Dog with LCx stenosis

20ISMRM 2006

Promising results for cardiac MR @ 3T.Limitations for SSFP cineThe increased SNR is advantageous for viability imaging, dynamic angiography and perfusion imaging.

Areas to be addressedprotocols and sequence design with reduced SAR, reduced B1 sensitivityContrast agents?

SummarySummary

3T Functional Cardiac Imaging

Gadomer, pig study. Schering AG, Inc.

3T Functional Cardiac Imaging

Gadomer, pig study. Schering AG, Inc.

21ISMRM 2006

3T Functional Cardiac Imaging

3T Functional Cardiac Imaging

3T Functional Cardiac Imaging

22ISMRM 2006

Thank you