International Journal of Hyperthermia (Jan 2021)

Predicting ablation zones with multislice volumetric 2-D magnetic resonance thermal imaging

  • Zahabiya Campwala,
  • Benjamin Szewczyk,
  • Teresa Maietta,
  • Rachel Trowbridge,
  • Matthew Tarasek,
  • Chitresh Bhushan,
  • Eric Fiveland,
  • Goutam Ghoshal,
  • Tamas Heffter,
  • Katie Gandomi,
  • Paulo Alberto Carvalho,
  • Christopher Nycz,
  • Erin Jeannotte,
  • Michael Staudt,
  • Julia Nalwalk,
  • Abigail Hellman,
  • Zhanyue Zhao,
  • E. Clif Burdette,
  • Gregory Fischer,
  • Desmond Yeo,
  • Julie G. Pilitsis

DOI
https://doi.org/10.1080/02656736.2021.1936215
Journal volume & issue
Vol. 38, no. 1
pp. 907 – 915

Abstract

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Background High-intensity focused ultrasound (HIFU) serves as a noninvasive stereotactic system for the ablation of brain metastases; however, treatments are limited to simple geometries and energy delivery is limited by the high acoustic attenuation of the calvarium. Minimally-invasive magnetic resonance-guided robotically-assisted (MRgRA) needle-based therapeutic ultrasound (NBTU) using multislice volumetric 2-D magnetic resonance thermal imaging (MRTI) overcomes these limitations and has potential to produce less collateral tissue damage than current methods. Objective To correlate multislice volumetric 2-D MRTI volumes with histologically confirmed regions of tissue damage in MRgRA NBTU. Methods Seven swine underwent a total of 8 frontal MRgRA NBTU lesions. MRTI ablation volumes were compared to histologic tissue damage on brain sections stained with 2,3,5-triphenyltetrazolium chloride (TTC). Bland-Altman analyses and correlation trends were used to compare MRTI and TTC ablation volumes. Results Data from the initial and third swine’s ablations were excluded due to sub-optimal tissue staining. For the remaining ablations (n = 6), the limits of agreement between the MRTI and histologic volumes ranged from −0.149 cm3 to 0.252 cm3 with a mean difference of 0.052 ± 0.042 cm3 (11.1%). There was a high correlation between the MRTI and histology volumes (r2 = 0.831) with a strong linear relationship (r = 0.868). Conclusion We used a volumetric MRTI technique to accurately track thermal changes during MRgRA NBTU in preparation for human trials. Improved volumetric coverage with MRTI enhanced our delivery of therapy and has far-reaching implications for focused ultrasound in the broader clinical setting.

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