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Table 3 Detailed summary of the MRI acquisition parameters

From: Brain imaging predictors and the international study to predict optimized treatment for depression: study protocol for a randomized controlled trial

Domain

Task/Scan type

MRI/Autonomic measures

Scan protocol/Task description

Structural scans

T1

Gray/white matter volume

Scan protocol: 3D T1 weighted high resolution SPGR MRI scan, TR = 8.3 ms, TE = 3.2 ms, Flip angle = 110, TI = 500 ms, NEX = 1, Matrix = 256 × 256, resolution = 1 mm × 1 mm, 180 contiguous 1 mm sagittal slices.

Cortical thickness

Cortical surface area

Diffusion Tensor Imaging (DTI)

Fractional Anisotropy (FA), mean (MD), axial (AD), radial (RD) diffusivity measures for white matter regions and fiber tracts

Scan protocol: Spin echo DTI echo planar imaging scan, 42 directions, b value = 1,250, TR = 17,000 ms, TE = 95 ms, NEX = 1, Matrix = 128 × 128, resolution = 1.72 mm × 1.72 mm, 70 contiguous 2.5 mm axial/oblique slices covering the whole brain.

PD/T2

Proton density

Scan protocol: 2D Fast Spin echo scan, TR = 4,000 ms, TE1 = 6.4 ms, TE2 = 102 ms, NEX = 1, Matrix = 256 × 256, resolution = 0.86 mm × 0.86 mm, ETL = 16, 70 contiguous 2.5 mm axial/oblique slices covering whole brain.

T2 structural scan for clinical evaluation

Functional scans

Oddball

Changes in fMRI BOLD signal

Scan protocol: Echo planar imaging scan, TR = 2,500 ms, TE = 27.5 ms, Flip angle = 900, NEX = 1, Matrix = 64 × 64, resolution = 3.75 mm × 3.75 mm, 40 contiguous 3.5 mm axial/oblique slices covering whole brain in each volume, total 120 volumes.

Average heart rate

Average skin conductance

Task description: 20 target (1,000 Hz) and 100 nontarget (50 Hz) tones presented one at a time at 75 db (50 ms each, ISI = 2.4 seconds).

Continuous performance test (CPT)

Changes in fMRI BOLD signal

Scan protocol: See Oddball protocol

Average heart rate

Task description: 120 stimuli are presented (B, C, D or G letters, for 200 ms each, ISI = 2.3 sec). Sixty were yellow letters to be held in working memory (no consecutive repetitions), 20 were 1-back sustained attention stimuli (consecutive repetitions of a letter in yellow) and 40 were perceptual baseline stimuli in white letters. Participants were measured for the number of errors or omissions.

Average skin conductance

Go-NoGo

Changes in fMRI BOLD signal

Scan protocol: See Oddball protocol

Average heart rate

Task description: 180 Go stimuli (word ‘press’ in green) and NoGo stimuli (word ‘press’ in red) each presented sequentially (500 ms each, ISI = .75 seconds). NoGo stimuli were not repeated more than three times in a row. Participants were measured for target detection rate, response time, errors of commission and errors of omission.

Average skin conductance

Emotion (masked ‘nonconscious’; Then unmasked ‘conscious’)

Changes in fMRI BOLD signal

Scan protocol: See Oddball protocol

Average heart rate

Task description: 240 3D evoked standardized facial expressions that depicted fear, anger, disgust, sadness, happiness or neutral were presented for 500 ms (ISI = .75 seconds). Stimuli were grouped into eight faces expressing the same emotion and were repeated five times in a pseudorandom order. Participants were assessed for explicit emotion processing for the ‘Masked’ condition.

Average skin conductance

The same set of facial expressions was presented for the ‘Unmasked’ condition; however, backward masking (expression presented for 10 ms immediately followed by a neutral face for 190 ms) was used to prevent conscious awareness of facial expression.

Additional scan

Phase map

Map magnetic field in homogeneities for EPI distortion correction

Scan protocol: Dual echo MRI scan, TE1 = 10 ms, TE2 = 12.5 ms, TR = 700 ms, Flip angle = 150, NEX = 1, Matrix = 128 × 128, 40 contiguous 3.5 mm axial/oblique slices.

  1. 2D Two-Dimensional, 3D Three-Dimensional, BOLD Blood oxygen level dependent; EPI, Echo-planar imaging, ETL Echo-train length, fMRI Functional magnetic resonance imaging, ISI Inter-stimulus interval, MRI Magnetic resonance imaging, NEX Number of excitations, PD Proton density, SPGR Spoiled gradient recalled, TE Echo time, TR Repetition time.