Calibration WG

Projects published

• QA Analysis Friedman L; Glover GH. Report on a multicenter fMRI quality assurance protocol. JMRI 23:827-839 (2006).

• Smoothness equalizationFriedman L; Glover GH; Kranz D; Magnotta V; FIRST BIRN. Reducing Scanner-to-Scanner Variability of Activation in a Multi-center fMRI Study: Role of Smoothness Equalization. NeuroImage 32:1656-68 (2006).

Calibration WG

Projects published

• BH Thomason ME; Burrows BE; Gabrieli JDE; Glover GH. Breath holding reveals differences in fMRI BOLD signal in children and adults. NeuroImage 25:824-837 (2005).

Thomason ME; Foland LC; Glover GH. Calibration of BOLD fMRI using Breath-holding reduces group variance during a cognitive task. Human Brain Mapping (Epub May 2006).

Calibration WG

Projects eliminated

• SM None of the areas were deemed reliable,esp. for Sz.

Calibration WG

Projects underway

•  Perfusion measurement• BH calib• Coil comparison- Multichannel vs. single channel

Calibration WG

Projects underway

•  Perfusion measurement• BH calib• Coil comparison- Multichannel vs. single channel

No calib

BH Calibration: Individual SubsCalib

5 ≤ t ≤ 20M. Thomason et al. 2006

No cal Calib

3.5 ≤ t ≤ 10

vol = 1.24 @ p .001 vol = 1.0

BH Calibration: Group Activation

M. Thomason et al. 2006

Calibration: SWM

0

500

1000

1500

2000

2500

SWM SWM calib

Acti

vati

on v

olum

e

sd: p = 0.05 *vol: ns

5 subjects, parietal

M. Thomason et al. 2006

Control of Inspiration

no control

BOLD Results

w/control

Residuals across 8 trials

fluctuation

0.000

0.050

0.100

0.150

0.200

0.250

BOLD, fluctuation Psychophysical, std

vari

atio

n/si

gnal

varncc

* (p=0.006)

* (p=0.005)

N = 10 subs

const cntl

no cntl

Single Subject

SM

BOLD response in normals: BH & SM

BH

Red: 4 non-smokersBlue: 4 smokers

Calibration WG

Projects underway

•  Perfusion measurement• BH calib• Coil comparison- Multichannel vs. single channel

Ratio 8/1

STAN SUB1

200-->

200-->

2.5->

ALL SCALES START AT 0.0

SFNR – CP COIL

SFNR – 8-CHANNEL COIL

COMPARING COILS ON SFNR

UCIR SUB1 UCIR SUB2 MINN SUB1

Ratio 8/1

YALE SUB1 YALE SUB2

200-->

200-->

2.5->

ALL SCALES START AT 0.0

SFNR – CP COIL

SFNR – 8-CHANNEL COIL

COMPARING COILS ON SFNR

YALE SUB3

UnsmoothedRatio 8/1

YALE SUB1 YALE SUB2

2.5->

ALL SCALES START AT 0.0

COMPARING COILS ON SFNR

YALE SUB3 YALE SUB3

Smoothed10 mm FWHM

Ratio 8/1

2.5->

Conclusions from Resting State Analyses

• 8 channel coil has less percent noise than 1 channel coil when unsmoothed

• Smoothing dramatically reduced noise• Smoothing equalizes noise of the two coils to

a remarkable extent• Little to no advantage to multichannel coils in

SFNR or Percent Noise when data smoothed to conventional levels (FWHM = 7 – 10)

Auditory Oddball Data

• 3 subjects• 2 tasks/per study:

– Auditory Oddball (4 runs, 143 TRs, 286 sec)• FBIRN Phase II sequence, no PACE,

ascending acquisition, TR=2.0, 64x64 matrix, no apodization filter.

Percent Signal ChangeLeft Motor

CortexLeft BA

40Ant.

CingulateLeft BA

22Left BA

41Right BA

47Right

CB

MultiSingle

1 Channel Coil 8 Channel Coil

T-value maps: t-values are for the 3-6 second time point

T=0.0

T=3.9, p <0.0001

threshold T=2.81p <0.005

Preliminary Conclusion• Some evidence for a Superior-to-inferior gradient in

the relationship between the coils.• At superior levels (left motor cortex, left BA 40) both

Percent Signal Change and CNR (t-values) are elevated in the 8 channel coil

• At inferior level (right cerebellum, BA47), single channel coil is stronger both for Percent Signal Change and CNR.

• At intermediate levels, the coils appear to perform similarly.

Thoughts on WhyThe Answer is Probably Hematocrit

Smoking Increases Hematocrit Hemocrit declines with age.

Hypothesis: Although both BOLD and BHdepend on Hematocrit, BH dependence is much stronger, leading to increased BH response in smokers