Sequence Overview
Sequence Type: Diffusion-Weighted Imaging (DWI) with Advanced Motion Correction

Field Strength: 1.5T / 3.0T

Primary Applications:

Acute Stroke Imaging

Tumor Characterization (ADC Mapping)

Prostate Cancer Detection

Vendor Classification: Proprietary CW Protocol (2014 Release)

Key Parameters
1. Diffusion Encoding
Parameter Settings Clinical Relevance
b-values 0, 500, 1000 s/mm² (adjustable) Standard stroke protocol (optional: b=1500 for high-contrast)
Diffusion Directions 3-orthogonal (DWI) / 20+ (DTI optional) Stroke vs. fiber tracking
TE (Echo Time) 80-100 ms (1.5T) / 60-80 ms (3T) Minimizes T2 shine-through
2. Spatial Encoding
Matrix: 128×128 (reconstructed to 256×256)

Slice Thickness: 4-5 mm (stroke) / 3 mm (prostate)

FOV: 230×230 mm (brain) / 200×200 mm (body)

3. Motion & Artifact Control
EPI Factor: 96 (reduced geometric distortion)

Parallel Imaging: GRAPPA 2× (SENSE optional)

Fat Suppression: Spectral Pre-saturation (SPIR)

Clinical Protocol Examples
1. Acute Stroke Protocol (Brain)
Recommended Settings:

b=0, 1000 s/mm², TE=90 ms (1.5T)

5 mm slices, 128×128 matrix

Scan Time: 45 sec

Key Features:

Hyperacute ischemia detection (ADC map generation)

Reduced susceptibility artifacts (vs. standard EPI-DWI)

2. Prostate Cancer (DWI with High b-value)
Recommended Settings:

b=50, 800, 1500 s/mm², TE=80 ms (3T)

3 mm slices, endorectal coil (optional)

Scan Time: 4 min

Performance Metrics
SNR (b=0): ≥25 dB (white matter)

Geometric Distortion: <2% (vs. standard EPI)

ADC Map Accuracy: ±5% vs. phantom standards

Technologist Notes
1. Protocol Optimization
For 3T: Reduce TE to minimize SAR

Body DWI: Add respiratory triggering (liver/pancreas)

2. Troubleshooting
Ghosting Artifacts: Enable phase oversampling

Eddy Current Distortion: Use higher bandwidth (±1500 Hz/pixel)

3. Limitations
Not Recommended for:

Metal implants (non-MARS compatible)

Ultrafast dynamic studies (use SE-EPI instead)