The stability of diffusion measurements with simultaneous multi-slice imaging: a multi-scanner, multi-site,...

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Quantitative Imaging
• Medical Physics

Background:

• Apparent diffusion coefficient (ADC) measurements are crucial for quantitative diffusion MRI.
• Simultaneous multi-slice (SMS) acceleration is increasingly used to reduce scan times.
• The impact of SMS acceleration on ADC accuracy across different MRI platforms is not fully understood.

Purpose of the Study:

• To evaluate the effect of SMS acceleration on ADC measurement accuracy and repeatability.
• To compare ADC measurements across multiple MRI platforms using a traceable diffusion phantom.
• To determine the optimal SMS acceleration factor for quantitative diffusion imaging.

Main Methods:

• A multi-center, multi-vendor test-retest study was performed using a CaliberMRI diffusion phantom.
• Diffusion-weighted images were acquired with SMS acceleration factors of 0, 2, 3, and 4.
• ADC values were compared to NIST reference standards, and signal-to-noise ratio (SNR) was calculated.

Main Results:

• Scanners overestimated ADC by an average of 4%.
• SMS factors 3 and 4 introduced significant systematic biases (4.62% and 9.22% overestimation, respectively).
• Low SMS acceleration (factor 2) did not significantly bias ADC measurements, and repeatability remained high despite reduced SNR.

Conclusions:

• Higher SMS acceleration factors (≥3) can introduce bias and degrade image quality in ADC measurements.
• Low SMS acceleration (factor 2) is suitable for reducing scan times without compromising ADC accuracy.
• Caution is needed when using higher SMS factors for absolute ADC quantification across platforms.