Advanced Processing Enhances Free-Breathing SMS-DWI for Liver Metastasis Imaging

Overview

This study compared conventional diffusion-weighted imaging (DWI) with prototype simultaneous multi-slice (SMS) DWI, with and without advanced processing, in patients with liver metastases. Advanced processing integrated with SMS-DWI improved image quality and maintained reliable apparent diffusion coefficient (ADC) measurements while reducing acquisition time.

Background

Diffusion-weighted imaging (DWI) is a key MRI technique for detecting and characterizing liver tumors, assessing therapy response, and predicting outcomes. Respiratory and cardiac motion can degrade liver DWI quality, with free-breathing acquisitions favored for higher signal-to-noise ratio and reproducibility despite longer scan times. Simultaneous multi-slice (SMS) acquisition accelerates free-breathing DWI, and advanced processing methods may further enhance image quality, but their added benefit compared to SMS alone was previously unclear.

Data Highlights

Key Findings

• Prototype SMS-DWI reduced acquisition time by approximately 25% compared to conventional DWI (2:46 min vs. 3:37 min).
• Advanced processing applied to SMS-DWI further improved image quality beyond SMS-DWI alone.
• Monopolar diffusion encoding was preferred over bipolar for SMS-DWI due to shorter echo time and better signal-to-noise ratio.
• ADC values derived from SMS-DWI with and without advanced processing were comparable, supporting quantitative reliability.
• Free-breathing acquisition with SMS-DWI and advanced processing maintained high reproducibility and reduced motion artifacts through non-rigid motion correction and adaptive averaging.

Clinical Implications

Integrating advanced processing with free-breathing SMS-DWI enables faster liver diffusion imaging without compromising image quality or ADC accuracy. This approach can be incorporated into clinical liver MRI protocols to improve patient throughput and diagnostic confidence, particularly in oncology patients with liver metastases. The use of monopolar diffusion encoding with advanced processing optimizes the balance between scan time and image fidelity.

Conclusion

Advanced processing combined with simultaneous multi-slice acquisition significantly enhances free-breathing liver DWI by improving image quality and maintaining quantitative accuracy while reducing scan time. This technique offers a promising improvement over conventional DWI for oncological liver imaging.

References

1. Le Bihan et al. 1986 -- Diffusion MR imaging: clinical applications
2. Taouli et al. 2010 -- Diffusion-weighted MRI in liver tumors
3. Koh et al. 2011 -- DWI for tumor response assessment
4. Yamada et al. 1999 -- Free-breathing vs breath-hold DWI
5. Kwee et al. 2009 -- Reproducibility of liver ADC measurements
6. Heijmen et al. 2010 -- Respiratory triggering in liver DWI
7. Setsompop et al. 2012 -- Simultaneous multi-slice imaging
8. Heinrich et al. 2018 -- Advanced processing in SMS-DWI
9. Baron et al. 2019 -- SMS-DWI in liver metastasis patients
10. Smith et al. 2020 -- SMS-DWI in pediatric abdominal imaging