Navigated Steady-State Diffusion Imaging of Knee Cartilage

1
Navigated Steady-StateDiffusion Imaging of Knee
Cartilage
Karla L. Miller, Garry E. Gold and John M.
Pauly Department of Electrical
Engineering Department of Radiology and Palo
Alto VA Medical Center Magnetic Resonance
Systems Research Laboratory Stanford University
2
DWI of cartilage

• in vitro studies
• Burstein 1993, Henkelman 1994, Xia 1994,
• Torzilli 1998, Frank 1999, Knauss 1999
• in vivo studies
• Gold 1998, Eustace 2000
• evidence for correlation to damage
• Xia 1995, Frank 1999

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DWI of cartilage challenges

• large gradient area
• small motions cause severe artifacts
• short T2 necessitates short TE

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Navigated Steady-State DWI

• large gradient area
• ? strong diffusion weighting per unit area
• small motions cause severe artifacts
• ? navigated motion correction
• short T2 necessitates short TE
• ? short TE, TR

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Outline

• Navigated SS-DWI
• In Vivo Results
• Discussion

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Diffusion weighted imaging
(1)
(2)
90
ACQ
(3)

1. encode position
2. spins diffuse
3. decode position

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SS-DWI diffusion sensitivity
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?
?
?
?
?

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SS-DWI diffusion sensitivity
?
?
?
?
?
?

90º
90º

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SS-DWI diffusion sensitivity
?
?
?
?
?
?


D nTR
n1,2,3
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Steady-state diffusion
TR lt T1,T2
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Navigated steady-state diffusion
TR lt T1,T2
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Navigated phase correction
kx
kx
ky
ky
high resolution
navigator

• navigator measures motion-induced phase
• phase-correct high resolution data
• (Poster 1112)

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In vivo experiments

• 5 subjects
• FOV 18 cm, 0.75 x 0.75 mm2, 5 mm thick
• TR 25 ms, ? 25?, nex 64
• G 1, 2.75, 4 G/cm, t 5 ms

beff 40, 275, 500 s/mm2 imaging time 7 minutes
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In vivo results
40 s/mm2
275 s/mm2
500 s/mm2
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Navigator correction
navigator corrected
uncorrected
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Conclusions

• diffusion has potential as contrast mechanism in
  cartilage
• SS-DWI enables in vivo knee cartilage diffusion
  imaging
• navigated motion-correction allows high
  resolution