Self-Navigated Kinematic Imaging of the Knee

Liheng Guo1, Antonio J. Machado Segundo2, J. Andrew Derbyshire3, John A. Carrino2, Daniel A. Herzka1

1 Department of Biomedical Engineering Johns Hopkins School of Medicine, Baltimore, MD, U.S.A.

2 Department of Radiology and Radiological Science Johns Hopkins School of Medicine, Baltimore, MD, U.S.A.

3 National Heart, Lung, and Blood Institute. National Institutes of Health, Bethesda, MD, U.S.A.

Adapted from: Podium Presentation, 19th Annual Meeting of the International Societyfor Magnetic Resonance in Medicine (ISMRM). Montreal, Canada, 2011

MOTIVATIONMusculoskeleto (MSK) MR imaging:

Superior soft-tissue contrast (unmatched by CT, X-Ray)Heavily used in diagnostic imagingDynamic images highly desired

“Movie” reveals joint, tendon motion Invaluable in functional evaluation

Blemker and McVeigh, ISMRM, 2006 (Abstract 3619)

Current Image QualityLow resolution

K-SPACE TRAJECTORIESTR 1 TR 2

… …Time

Derbyshire, et al. Efficient implementation of hardware-optimized gradient sequences for real-time imaging. Magnetic Resonance in Medicine, 64: 1814–1820. 2010.

METHOD: MOTION MEASUREMENTS

+ –

+ : 5500 projections (70sec)

– : 5500 projections (70sec)

Time

MRI machine programmed to also measure knee motion

HUMAN IMAGING EXPERIMENTSSiemens Verio 3T MRI, custom-programmedStandard Knee Coil: ~20° range of motionRepeated extension / flexion, ~1 minute,

~3sec/cycle

Knee coil

OBTAINED MOTION MEASUREMENTS

+ projections

– projections

+ projections

– projections

+ projections

– projections

MOTION CYCLE TRACKINGMotion cycles extracted by custom algorithm

+ projections

– projections

+ gating curve

– gating curve

Trigger corroboration

TRs

1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10

IMAGING DATA SORTINGData sorted into movie frames

… …

…

+ projections

– projections

RESULTS: DYNAMIC IMAGESResolution Achieved: 1×1mm

Stationary Reference Dynamic