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Tumor Rapid Fire Abstract

Tumor

Mizuho Minimally Invasive Brain Tumor Surgery Award: The Impact of Perilesional Heatsink Structures on Ablation Volumes and Symmetry in Laser Interstitial Thermal Therapy for Primary Central Nervous System Tumors

Sunday, May 5, 2024
2:09 PM – 2:13 PM CT
Location:  S405a
Disclosure(s):
Chandler N. Berke: No financial relationships to disclose
Michael Ivan, MD, MBS: No financial relationships to disclose
Ricardo Komotar, MD: No financial relationships to disclose
Introduction: Laser interstitial thermal therapy (LITT) has been demonstrated to be a viable, minimally invasive treatment option for primary central nervous system (CNS) tumors. The mechanism relies on precise heat and temperature control of the laser, and thus, is vulnerable to the impacts of perilesional heatsink structures, and the thermodynamic properties of the lesioned tissue.

Methods: Of the 254 LITT procedures performed at our institution, 132 procedures for primary CNS tumors fit inclusion criteria for our study. Extent of ablation (EOA) was calculated using pre-operative and post-operative contrast-enhancing peritumoral volumes. The radial asymmetry index (RAI) was calculated by measuring perpendicular distances from the proximal, medial, and distal points of the intralesional laser catheter to the edge of the ablation, bilaterally. Euclidean distances from these points to the closest heatsink, bilaterally, were also recorded. Pearson correlations and paired t-tests were performed.

Results: A total of 132 perilesional heat sinks were evaluated, with glioblastoma being the most common lesion pathology (77.1%). Tumors located within 5.1mm of a heatsink appear to be at greater risk of asymmetric ablation (p < 0.03). Euclidean distance to the closest heat sink partially correlated to EOA (r2 = 0.107, p< 0.002). There was no significant correlation between heat sink proximity and ablation asymmetry (p>0.05), but there was a small correlation between the medial RAI and EOA (r2 = 0.088, p< 0.01). When heatsinks were subdivided by anatomical structure, ventricles showed a statistically significant correlation between EOA and asymmetry from the medial catheter point (r2 = 0.383, p< 0.005).

Conclusion : This novel quantitative analysis demonstrates significant reductions in EOA and symmetric ablation for numerous perilesional heatsinks across multiple primary CNS tumor types. Neurosurgeons may anticipate ablation reductions in LITT if heatsinks, especially ventricles, are located within 5.1 mm of the tumor’s periphery. Further studies are needed to validate these findings and establish clear guidelines.