Clinical Study Report on Laser Interstitial Thermal Therapy (LITT) in Neurosurgery

Background Introduction

With the continuous progress of modern medical technology, Laser Interstitial Thermal Therapy (LITT) has gradually gained a foothold in the field of neurosurgical tumor treatment, especially in treating intracranial lesions that are difficult to approach or resistant to conventional treatments.1–5 LITT is a minimally invasive thermal ablation technique that can precisely target and ablate lesions without damaging healthy tissue, enabling the treatment of areas that are difficult to reach with traditional surgery.2,6,7 Over the past decade, the application of LITT has rapidly expanded, covering a variety of intracranial tumors such as newly diagnosed and recurrent gliomas, metastases, dural lesions, and radiation necrosis (RN).8–12 Further research has shown that LITT can enhance the effects of adjuvant therapies, such as promoting the diffusion of chemotherapeutic drugs, by disrupting the blood-brain barrier and devascularizing tumor tissue.11 Although multiple case series have reported the safety of LITT, these studies lack sufficient statistical representativeness due to small sample sizes or inadequate follow-up periods.

Research Source

This paper was authored by Muhammet Enes Gurses et al., from the Department of Neurological Surgery, University of Miami Miller School of Medicine, Hacettepe University Faculty of Medicine, and Ankara University School of Medicine. The paper was published online in the Journal of Neurosurgery on May 31, 2024.

Research Objectives

This study aimed to comprehensively evaluate the safety and efficacy of LITT in the treatment of brain tumors in neurosurgery, with a particular focus on the extent of ablation (EOA), time to recurrence (TTR), and overall survival (OS), through a retrospective cohort analysis of 313 brain tumor patients who underwent LITT treatment at a single center between 2013 and 2023.

Research Methods

Sample and Data Collection

From 6004 medical records, all 313 consecutive cases that underwent LITT treatment between 2013 and 2023 were screened. All surgeries were performed by a single neurosurgeon (R.J.K.) and were approved by the IRB. Patient information was de-identified according to the retrospective study design, so patient consent was not required. Indications for LITT included deep or eloquent lesions not amenable to open surgery or patients unresponsive to conventional treatments. Patients undergoing MRI-guided LITT had a Karnofsky Performance Status (KPS) score >50, an expected lifespan of at least 3 months, and no MRI contraindications.

Electronic medical records collected patient demographics, pre-operative deficits, diagnosis, pre- and post-operative magnetic resonance imaging, lesion characteristics, extent of ablation, post-operative complications, and post-operative deficits. Pre- and post-operative lesion volumes were measured using the freehand tool in the Philips PACS imaging system, with the lesion volume calculated as (length × width × height)/2, based on T1-weighted contrast-enhanced MRI or T2-weighted FLAIR images.

Experimental Methods

LITT procedures were performed using the Visualase Thermal Therapy System from Medtronic Inc., following the team’s established protocol. Preoperative thin-slice stereotactic MRI images were co-registered with intraoperative CT images to precisely define the lesion and plan the surgical trajectory. After insertion of a biopsy needle into the lesion, frozen section assessment was performed, and then a laser fiber was introduced to the deepest aspect of the lesion and secured for the maximal safe ablation. All patients underwent contrast-enhanced MRI on postoperative day 1 to assess the ablation volume.

Statistical Analysis

Statistical analyses were performed using SPSS software (version 23.0) and GraphPad Prism software (version 10.1.2). Kaplan-Meier survival curves were used to assess TTR and OS for all patients and stratified by lesion type, with log-rank tests to evaluate outcome differences between variables. Univariate and multivariate Cox regression analyses were performed to identify predictors of recurrence or OS, with a p-value < 0.05 considered statistically significant.

Research Results

Patient Characteristics

Between 2013 and 2023, 313 patients underwent LITT, with a mean age of 60.4 years (±13.3 years), and 58.5% were female. Lesion types included metastases (30%), glioblastomas (GBM, 41.6%), low-grade gliomas (LGG, 9.1%), radiation necrosis (RN, 11.4%), and meningiomas (2.2%). The permanent neurological deficit rate was 14%, with 8% experiencing new postoperative deficits.

LITT Technique and Treatment Outcomes

The Visualase Thermal Therapy System from Medtronic Inc. was used for LITT procedures. The laser ablation procedure involved inserting a laser fiber through a pre-planned trajectory, followed by ablation guided by MRI thermography to ensure temperature within the target range to avoid damaging nearby healthy tissue. The average procedure duration was 227.5 minutes (±71.6 minutes), with an average ablation time of 7.31 minutes (±3.93 minutes). A single LITT trajectory was sufficient in most cases (93.9%), and the extent of ablation exceeded 100% of the lesion volume in 75.7% of cases.

The mean follow-up time was 10.4 months, with 66.8% of patients surviving and 26.2% of lesions recurring. Kaplan-Meier analysis demonstrated significantly improved overall survival in GBM and metastatic patients with an extent of ablation >100% (p<0.05).

Predictors of Recurrence and Survival

Univariate Cox regression analysis showed that age, lesion grade, pre-operative lesion volume, and readmission within 30 days were significantly associated with overall survival (OS). Multivariate analysis revealed that high-grade lesions increased the risk of death by 2.29-fold, and pre-operative lesion volume >10 cm³ increased the risk of death by 2.05-fold. Older age (>60 years) and readmission within 30 days were associated with significantly poorer survival.

Lesion grade was associated with recurrence, with high-grade lesions increasing the risk of recurrence by 1.86-fold, but no other factors showed significance in the multivariate regression.

Conclusion

Through a comprehensive review of 313 LITT patients, this study provides evidence for the safety and efficacy of this technique in the treatment of neurosurgical tumors. LITT is a promising adjunctive treatment modality, particularly suitable for lesions inaccessible by conventional surgery. However, careful patient selection and treatment planning are still required to maximize the advantages of LITT.

Research Significance

This study is one of the largest investigations of LITT application to date, providing important guidance for future clinical practice. As a minimally invasive treatment option, LITT offers a new choice for patients who have failed conventional treatments or have lesions that are inoperable due to location. This research not only demonstrates the safety and efficacy of LITT but also provides valuable clinical data and experience for further optimization of LITT techniques.