Technical Note: Diffusion-weighted MRI with minimal distortion in head-and-neck radiotherapy using a turbo spin echo...

Area of Science:

• Radiotherapy and Medical Imaging
• Oncology and Diagnostic Techniques

Background:

• Diffusion-weighted (DW) MRI provides high contrast between tumors and surrounding tissues, making it valuable for radiotherapy tumor delineation.
• Conventional echo planar imaging (EPI) DW-MRI suffers from poor geometric accuracy, limiting its application in head-and-neck cancer patients.

Purpose of the Study:

• To implement and evaluate an alternative turbo spin echo sequence, DW-SPLICE, for improved geometric accuracy in DW-MRI of head-and-neck patients.
• To assess the feasibility of DW-SPLICE for accurate tumor delineation in radiotherapy treatment planning.

Main Methods:

• The DW-SPLICE sequence was implemented on a 3.0 T MRI system and tested in 10 patients positioned for radiotherapy.
• Image distortions were quantified using field map analysis at the gross tumor volume (GTV).
• Apparent diffusion coefficient (ADC) values were evaluated using an ice water phantom.

Main Results:

• DW-SPLICE images exhibited no significant image distortions, with a median distortion of 0.2 mm at the GTV.
• Conventional EPI DW-MRI showed a median distortion of 7.2 mm at the GTV.
• ADC values obtained with DW-SPLICE in an ice water phantom were consistent with established literature values.

Conclusions:

• DW-SPLICE enables diffusion-weighted imaging in the treatment position with superior geometric accuracy compared to conventional EPI.
• This technique facilitates precise target volume delineation for radiotherapy planning in head-and-neck cancer patients.