Coronary Magnetic Coronary Magnetic Resonance Imaging Resonance - - PowerPoint PPT Presentation

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Coronary Magnetic Coronary Magnetic Resonance Imaging Resonance Imaging Matthias Stuber, PhD Matthias Stuber, PhD Associate Professor Associate Professor Division of MRI Research Division of MRI Research Johns Hopkins University Johns

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SLIDE 1

Coronary Magnetic Resonance Imaging Coronary Magnetic Resonance Imaging

Matthias Stuber, PhD

Associate Professor Division of MRI Research Johns Hopkins University Baltimore, MD

Matthias Stuber, PhD

Associate Professor Division of MRI Research Johns Hopkins University Baltimore, MD

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SLIDE 2
  • The Need for MRI
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SLIDE 3

Background Background

  • X-ray coronary angiograpy (gold standard)

– Invasive – Radiation exposure for operator and patient – Small, but significant risk of complications – Substantial minority of patients are found to have no significant coronary stenosis (~30-50%)1 – High procedural costs ($3000-$6000)2 – Inability to identify early atherosclerotic disease

  • Both in the USA and in Germany ~1 million x-ray coronary

angiograms are performed each year2

  • X-ray coronary angiograpy (gold standard)

– Invasive – Radiation exposure for operator and patient – Small, but significant risk of complications – Substantial minority of patients are found to have no significant coronary stenosis (~30-50%)1 – High procedural costs ($3000-$6000)2 – Inability to identify early atherosclerotic disease

  • Both in the USA and in Germany ~1 million x-ray coronary

angiograms are performed each year2

1Budoff et al. Circulation 1996; 93: 898 22002 AHA Heart and Stroke Statistical Update

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SLIDE 4
  • Need for an alternative, non-invasive, more cost

efficient & patient friendlier technique, which.… – Accurately detects significant (≥50%) CAD – Rules out non-significant CAD

  • ⇒

Coronary Magnetic Resonance Angiography (MRA)

  • Need for an alternative, non-invasive, more cost

efficient & patient friendlier technique, which.… – Accurately detects significant (≥50%) CAD – Rules out non-significant CAD

  • ⇒

Coronary Magnetic Resonance Angiography (MRA)

Motivation Motivation

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SLIDE 5
  • Challenges
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SLIDE 6

Technical Challenges

  • Small caliber & geometry of the coronary arteries

– Necessitates a high spatial resolution & sufficient volumetric coverage.

  • Contrast

– Contrast enhancement between coronary blood-pool, and surrounding tissue (epicardial fat, myocardium).

  • Myocardial motion

– Effective suppression of intrinsic (RR-interval) and extrinsic (respiration) myocardial motion.

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SLIDE 7

Technical Challenges

Expiration Inspiration Intrinsic: Cardiac cycle: ~60/min; ~2cm Extrinsic: Respiratory cycle: ~12/min; ~2cm 32cm

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SLIDE 8
  • Solutions
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SLIDE 9

Technical Challenges & Solutions

  • No motion

suppression

  • No contrast

enhancement

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SLIDE 10

Technical Challenges & Solutions

  • Suppression of intrinsic myocardial motion

– ECG triggering, segmentation of data acquisition1, late diastolic image acquisition2

EKG

FFT

Image data acquisition

1) Edelman RR, Manning WJ, Burstein D. et al.: Radiology 181(3); 641-643 (1991). 2) Kim WY, Stuber M, Kissinger KV. et al.: J Magn Reson Imaging 14(4); 683-690 (2001).

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SLIDE 11

Technical Challenges & Solutions

  • ECG triggering
  • No resp. mot.

suppression

  • No contrast

enhancement

  • No motion

suppression

  • No contrast

enhancement

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SLIDE 12

Technical Challenges & Solutions

  • Suppression of extrinsic myocardial motion

– Breath-holding1 – Serial averaging2 – Bellows gating2 – Navigators2,3 – ‘Self’ Navigation4 – Hybrid (Navigators & Breath-hold)5

1) Edelman RR, Manning WJ, Burstein D. et al.: Radiology 181(3); 641-643 (1991). 2) Oshinski JN, Hofland L, Mukundan S. et al.: Radiology 201(3); (1996). 3) Li D, Kaushikkar S, Haacke, EM. Et al.: Radiology 201(3); (1996). 4) Hardy CJ, Saranathan M, Zhu Y. et al.: Magn Reson Med. 2000 Dec;44(6):940-946. 5) Huber M, Oelhafen M, Kozerke S. et al.: J Magn Reson Imaging 15(2); 210-214 (2002).

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SLIDE 13

Technical Challenges & Solutions

  • Suppression of extrinsic myocardial motion

– Breath-holding

  • Diaphragmatic drift/registration errors in serial breath-

holds (~1cm)1

  • Major operator and patient involvement
  • Patient compliance

→ Applicability to patients with coronary disease is limited → Removed flexibility for enhanced spatial resolution

⇒ Free-breathing approaches

1) Danias PG, Stuber M, Botnar, RM et al.: Am J Roentgenol, 171(2):395-397, (1998).

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SLIDE 14

Technical Challenges & Solutions

  • Suppression of extrinsic myocardial motion

– MR navigator technology: Navigator gating & tracking1

Lung Liver

time

Diaphragm

1.) McConnell et al.: Magn Reson Med 37(1); 148-152 (1997).

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SLIDE 15

Technical Challenges & Solutions

  • ECG triggering
  • No resp. mot.

suppression

  • No contrast

enhancement

  • No motion

suppression

  • No contrast

enhancement

  • ECG triggering
  • Navigator &

free breathing

  • No contrast

enhancement

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SLIDE 16

Contrast Generation

  • Contrast enhancement (lumen blood-pool and

surrounding epicardial fat, myocardium).

T1 [ms] T2 [ms] ∆ω ∆ω ∆ω ∆ω0 [Hz] flow Blood 1200 250 yes Muscle 850 50 no Fat 250 100 220 no

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SLIDE 17

Technical Challenges & Solutions

  • Contrast enhancement

– Endogenous contrast enhancement (T2Prep)

x y z 90

  • 90

180

RF

180 180 180

TE time

1) GA Wright, DG Nishimura, A Macovski, Magn Reson Med 17:126-140 (1991). 2) JH Brittain, et al., Magn Reson Med 33:689-696 (1995).

T2Blood: 250ms T2Myo: 50ms

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SLIDE 18

Technical Challenges & Solutions

  • ECG triggering
  • Navigator &

free breathing

  • No contrast

enhancement

  • ECG triggering
  • No resp. mot.

suppression

  • No contrast

enhancement

  • No motion

suppression

  • No contrast

enhancement

  • ECG triggering
  • Navigator
  • T2Prep
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SLIDE 19
  • State-of-the-Art & Comparison

to Gold Standard

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SLIDE 20

Technical Challenges & Solutions

1) Stuber M, Botnar RM, Danias PG et al.: J Am Coll Cardiol; 34(2):524-531 (1999). 1) Stuber M, Botnar RM, Danias PG et al.: J Am Coll Cardiol; 34(2):524-531 (1999).

T R IGGERDEL AY

NAVIGAT OR 30ms 50ms F ATS AT 15ms 3D T FE 70m s

Motion T racking

(S cout S can) (HR

  • S

can)

E CG

T 2P rep 3D T FE

  • E

P I

T R IGGERDEL AY

NAVIGAT OR 30ms 50ms F ATS AT 15ms 3D T FE 70m s

Motion T racking

(S cout S can) (HR

  • S

can)

E CG

T 2P rep 3D T FE

  • E

P I

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SLIDE 21

Study (n)

Sensitivity Specificity

Sandstede’99 (23)

81 89

Huber’99 (?)

73 50

Sardinelli’00 (39)

90 90

Lethimonnier’99 (20)

65 93

Ikonen’00 (14)

84 70

Sommer’02 (77)

81 97

Single Center Coronary MRA Results*

Adapted from: Sommer et al.: Rofo Fortschr Geb Rontgenstr N 2002; 459-466

* Navigators & free breathing

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SLIDE 22

Multicenter Coronary MRA Study

  • Purpose & Methods

– Using uniform hardware, software & methodology1,2, to examine the sensitivity, specificity, PPV, NPV of coronary MRA for the diagnosis of significant disease of the proximal coronary arteries. – Prospective comparison with gold standard (MR prior to X- Ray coronary angiography, independent core lab) – 109 patients from 8 international centers in Philips Cardiac MR Users network.

  • Purpose & Methods

– Using uniform hardware, software & methodology1,2, to examine the sensitivity, specificity, PPV, NPV of coronary MRA for the diagnosis of significant disease of the proximal coronary arteries. – Prospective comparison with gold standard (MR prior to X- Ray coronary angiography, independent core lab) – 109 patients from 8 international centers in Philips Cardiac MR Users network.

1) Stuber M, Botnar RM, Danias PG et al.: J Am Coll Cardiol; 34(2):524-531 (1999). 2) Botnar RM, Stuber M, Danias PG et al.: Circulation; 99(24):3139-3148 (1999). 1) Stuber M, Botnar RM, Danias PG et al.: J Am Coll Cardiol; 34(2):524-531 (1999). 2) Botnar RM, Stuber M, Danias PG et al.: Circulation; 99(24):3139-3148 (1999).

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SLIDE 23

Multicenter Coronary MRA Results*

Any CAD [%] LM/3VD [%] Sensitivity 93 100 Specificity 42 85 PPV 70 54 NPV 81 100

  • Results (Detection of >50% stenosis, n=109)
  • Results (Detection of >50% stenosis, n=109)

1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001). 1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001).

* Navigators & free breathing

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SLIDE 24

Multicenter Coronary MRA Study

Aarhus Berlin Boston Leiden Texas Leeds Zürich

1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001). 1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001).

Köln

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SLIDE 25

Multicenter Coronary MRA Study

1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001). 1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001).

Patient with LM/LAD & LCX disease Patient with 2 lesions in proximal RCA

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SLIDE 26

Multicenter Coronary MRA Study

  • Conclusions
  • Among patients referred for elective coronary

angiography, coronary MRA with real-time navigator technology and T2Prep

– Accurately detects significant (≥50% lumen ∅) coronary artery disease1. – Reliably rules out non-significant coronary artery disease1

  • Conclusions
  • Among patients referred for elective coronary

angiography, coronary MRA with real-time navigator technology and T2Prep

– Accurately detects significant (≥50% lumen ∅) coronary artery disease1. – Reliably rules out non-significant coronary artery disease1

1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001). 1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001).

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SLIDE 27

Multicenter Coronary MRA Study

  • Conclusions

⇒ There is a need for alternative methods which

  • ultimately improve specificity of coronary MRA

in general

  • provide additional/different information
  • support access to more distal/branching vessels
  • Enables visualization of atherosclerotic disease

that precedes lumen-narrowing

  • Conclusions

⇒ There is a need for alternative methods which

  • ultimately improve specificity of coronary MRA

in general

  • provide additional/different information
  • support access to more distal/branching vessels
  • Enables visualization of atherosclerotic disease

that precedes lumen-narrowing

1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001). 1) Kim WY, Danias PG, Stuber M. et al.: N Engl J Med;345(26):1863-1869 (2001).

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SLIDE 28
  • Outlook and Promise
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SLIDE 29

Works in Progress and Outlook

  • Alternative methods include

– Contrast agents for coronary MRA – SSFP coronary MRA – ‘Whole heart’ imaging – Arterial spin labeling – Interventional coronary MRI – Coronary vessel wall imaging, atherosclerosis & molecular imaging – High field (3T) coronary MRI

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SLIDE 30
  • CONTRAST AGENTS
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SLIDE 31

Contrast Generation

T1 [ms] T2 [ms] ∆ω ∆ω ∆ω ∆ω0 [Hz] flow Blood 1200 250 yes Muscle 850 50 no Fat 250 50 250 no

  • Contrast agents (Blood-Pool Agents)

~100 ~300

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SLIDE 32

Contrast Generation

  • 1.5
  • 1
  • 0.5

0.5 1 1.5 100 200 300 400 500 600 700 800 900 1000 Time [ms] Magnetization M z [%M0]

Blood Muscle Fat

Inversion Pre-Pulse LV Navigator Imaging Fat Sat (SPIR)

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SLIDE 33

Contrast Generation

T R IGGE RDE L AY

NAVIGAT OR 35ms F ATS AT 15ms 70ms

Motion T racking

(S cout S can) (HR

  • S

can) E CG

INVE R S ION

T i

30ms INVERSION

1) Stuber M, Botnar RM, Danias PG et al.: J Magn Reson Imaging; 10(5):790-799 (1999). 1) Stuber M, Botnar RM, Danias PG et al.: J Magn Reson Imaging; 10(5):790-799 (1999).

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SLIDE 34

Intravascular Contrast Agent

Huber et al.: Magn Reson Med; Magn Reson Med. 2003 Jan;49(1):115-21 Courtesy: Paetsch I, Nagel E, Fleck E; Deutsches Herzzentrum Berlin

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SLIDE 35
  • Coronary Vessel Wall Imaging
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SLIDE 36

1) Glagov S, Weisenberg E, Zarins CK et al.: N Engl J Med 316(22); 1371-1375 (1987).

lipid core lumen wall

50%

plaque disruption with thrombosis foam cells Wall inflammation

macrophages, LDL,...

25%

macrophages tissue factor

angiographically invisible!!

0.5..1mm

Background

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SLIDE 37

1) Toussaint JF, LaMuraglia GM, Southern JF et al.: Circulation 94(5);932-938 (1996). 2) Wasserman BA, Smith WI, Trout HH et al.: Radiology 223; 566-573 (2002). 3) Yuan C, Kerwin WS, Ferguson MS et al.: J Magn Reson Imaging 15; 62-67 (2002).

<3mm <1mm

  • MRI has demonstrated ability to visualize the

vessel wall and its components (carotids, aorta)1-3

  • Coronary vessel wall imaging is technically

very challenging

– Small dimensions – Constant motion – Contrast ?

Introduction Introduction

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SLIDE 38

Methods: Contrast Generation

  • Contrast enhancement concept: ‘Dual inversion’

1) Edelman RR, Chien, D, Kim D: Radiology; 181(3); 655-660 (1991).

Blood Vessel Wall Mz time RF

Non-selective (180°) Selective (180°)

Imaging

} Dual-inversion1

TI

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SLIDE 39

Labeling Delay (TL) r Delay (TD)

IMAGING

ECG Trigger Delay (TD)

Trigger Delay Inversion Delay (TI)

2D Selective Re-Inversion Navigator Spiral Imaging (<60ms)

45° 90°

Non-Selective Inversion

Methods: Motion Suppression

Gx Gy RF Gz t

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SLIDE 40

Coronary Vessel Wall Imaging

3D SSFP 3D SSFP 4th Order Local Inversion & 3D Spiral 4th Order Local Inversion & 3D Spiral

RCA wall RCA wall

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SLIDE 41

luminal irregularities

79y old patient with ”luminal irregularities” in RCA

X-ray

thickened wall thickened wall thickened wall thickened wall

RCA lumen RCA lumen MR wall image

* Botnar RM et al.: Magn Reson Med 2001 Nov;46(5):848-54 2002 * Kim W, Stuber M, Manning WJ et. Al.: Circulation 2002

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SLIDE 42

RCA Vessel Wall Thickness

0.00 0.50 1.00 1.50 2.00 2.50

3

Wall thickness [mm]

Healthy subjects Patients with non-significant CAD

P<0.01 1.0±0.2 mm 1.7±0.3mm

* Kim W, Stuber M, Manning WJ et. Al.: Circulation 2002

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SLIDE 43

RCA Lumen Diameter

P<0.01 1.0±0.2 mm 1.7±0.3mm

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

3

Lumen Diameter [mm]

Healthy subjects Patients with non-significant CAD

P=0.53 3.4±0.5 mm 3.6±0.7 mm

* Kim W, Stuber M, Manning WJ et. Al.: Circulation 2002

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SLIDE 44
  • High-Field Coronary MRA
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SLIDE 45

Coronary MRA at 3 Tesla

(0.34x0.35x1.5mm voxel size)

→ MR System

→ Philips 3T Achieva → Dual Quasar Gradient System → 6-Element Cardiac SENSE Coil

→ Imaging Sequence

→ 3D TFE → TE/TR: 2.3/7.6ms → Matrix/FOV: 800/270mm → Acquired Voxel Size: 0.34x0.35x1.5mm → Reconstructed Voxel Size: 0.26x0.26x0.75mm → Fat Saturation

→ Motion Suppression

→ FREEZE (automated prescription of diastolic rest period) → VECG → Free-Breathing & Real-Time Navigator

  • M. Stuber, A. Ustun, R.G. Weiss, JHU