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Stanford Radiology LPCH

Fast Pediatric MRI

Shreyas Vasanawala, MD/PhD

Stanford University

Lucile Packard Children’s Hospital

2013 Par Lab Celebration

How fast computation is changing our clinical practice

Stanford Radiology LPCH

Stanford Radiology LPCH

Current Solution

INVASIVE

LIMITS

ACCESS

Stanford Radiology LPCH

Stanford Radiology LPCH

Why is MRI lengthy?

• Complex protocols with multiple sets of

images in multiple planes

• Encoding spatial information takes time

Stanford Radiology LPCH

MRI Sampling Concept

Fourier

transform

Fourier (k)-space Image space

Stanford Radiology LPCH

Stanford Radiology LPCH

Ringl et. al.,

Radiology

Nov. 2007

8:1 compression ratio

visually indistinguishable

Stanford Radiology LPCH

Opportunity: Images are compressible.

Why spend time trying to collect information that is not there?

Compressed Sensing

Stanford Radiology LPCH

Concept

Fourier

transform

k-space Image space

Stanford Radiology LPCH

Teleradiology approach: First collect, then compress

Compression

101000110100 1101011 Compression

Stanford Radiology LPCH

Compressed Sensing

Instead: Sample less, then reconstruct.

Donoho

IEEE TIF ‘06

Candes et al.

IEEE TIF ’06

101000110100 1101011 Compression

Courtesy M. Lustig

Stanford Radiology LPCH

No CS CS

Miki

Lustig

2 fold

speedup, i.e.

15 second

breath-hold vs

usual 30 seconds

Stanford Radiology LPCH

Barrier to clinical use

Image reconstruction time

Stanford Radiology LPCH

Use enabled by Fast Image

Reconstruction ( < 1 minute)

Mark Murphy Kurt Keutzer

Stanford Radiology LPCH

No CS CS

Stanford Radiology LPCH

5 year old male No CS CS

7.2 x

speed

Stanford Radiology LPCH

Since

Last

Year:

Free-

breathing

MRI

Stanford Radiology LPCH

Stanford Radiology LPCH

Resolve cardiac motion

Joseph

Cheng

Michael

Lustig

Tao

Zhang

Stanford Radiology LPCH

Exam goals:

Heart anatomy

Heart Chamber volumes

Chamber wall motion

Quantification of blood flow

Stanford Radiology LPCH

Single 4D scan

Real-time stereoscopic

rendering/navigation of data

8 minute scan gives

same information as

conventional 90 minute

scan

Stanford Radiology LPCH

L1-SPIRIT ARC/GRAPPA

MP

R

Vo

lum

e-r

en

deri

ng

> 1 day reconstruction time

reduced to under 20 minutes as a

result of ParLab innovation

Stanford Radiology LPCH

Stanford Radiology LPCH

Stanford Radiology LPCH

Could go even faster

Stanford Radiology LPCH

Thank you Par Lab

Briefer, lighter, safer anesthesia

for pediatric MRI