Magnetic Resonance Image-Guided Laser Interstitial Thermal Therapy for Intracranial Metastases

MRgLITT is a minimally invasive neurosurgical technique that employs laser energy to thermally ablate intracranial metastatic tumors under real-time MRI guidance. It combines stereotactic navigation with thermal imaging for precise tumor targeting.

• Intracranial metastases in deep-seated or eloquent brain regions
• Recurrence after stereotactic radiosurgery (SRS) or whole brain radiation therapy (WBRT)
• Radiation necrosis not amenable to resection
• Poor surgical candidates due to comorbidities or tumor location

—- Magnetic Resonance Image-Guided Laser Interstitial Thermal Therapy (MRgLITT) for intracranial metastases is not a standard first-line treatment, but it may be indicated in highly specific scenarios — particularly when other options are limited or contraindicated.

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### ✅ Indications (when MRgLITT *may* be appropriate):

1. Radiation necrosis after stereotactic radiosurgery (SRS):

• MRgLITT can effectively target necrotic tissue while sparing surrounding brain structures.
• Especially useful when it's difficult to distinguish necrosis from recurrence radiographically.

2. Recurrent or progressive metastases after prior SRS or surgery:

• For lesions not amenable to repeat surgery or radiation.
• Particularly in eloquent or deep-seated locations.

3. Patients who are poor candidates for open craniotomy due to:

• Age
• Comorbidities
• Previous surgeries or radiotherapy

4. Lesions <3 cm, well-circumscribed, and visible in MRI:

• MRgLITT is more effective when the lesion is accessible for thermal ablation and can be clearly monitored with MRI thermography.

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### ❌ When it's *not* indicated:

* Large tumors (>3–3.5 cm) or with mass effect, where open resection would provide more effective decompression. * Multifocal disease where systemic therapy or WBRT (whole-brain radiation therapy) is more appropriate. * Uncontrolled edema, midline shift, or intracranial hypertension. * Lesions in proximity to critical thermal-sensitive structures (optic apparatus, brainstem) with high risk of collateral damage. * Poor MRI visibility (e.g., lesions not well delineated on T1 or T2 imaging).

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### 🔍 Guideline Positioning:

* No major guidelines (e.g., NCCN, EANO) currently recommend MRgLITT as standard of care, but it is discussed as an emerging or salvage technique. * Most data come from retrospective series, small cohorts, and expert opinion—no RCTs yet define its true comparative efficacy.

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### ⚖️ Bottom Line:

MRgLITT is indicated in selected patients with brain metastases—especially post-radiation necrosis or recurrence—when conventional surgery or repeat radiation is not feasible. It is not a replacement for standard treatments but a valuable adjunct in experienced centers.

• Large tumor volume (>3 cm diameter)
• Extensive peritumoral edema with mass effect
• Coagulopathy or uncontrolled bleeding risk
• Inability to undergo MRI

1. Stereotactic placement of a laser fiber through a burr hole
2. Intraoperative MRI (1.5T or 3T) for:
   • Confirmation of trajectory
   • Real-time thermometry
   • Monitoring of ablation volume
3. Thermal ablation conducted in a controlled manner, typically 3-10 minutes per cycle

• Minimally invasive with short hospital stay
• Real-time feedback reduces collateral damage
• Repeatable and combinable with radiation or systemic therapy
• Useful in eloquent or deep-seated lesions

• High cost and limited availability
• Not suitable for large or multifocal lesions
• Limited data on long-term survival benefit
• Requires MRI-compatible surgical environment

• Local control rates: ~70-90% in selected cases
• Median progression-free survival: variable, often 4–9 months
• Neurological improvement in selected cases (e.g., edema-related deficits)
• Lower morbidity than open surgery in properly selected patients

• Perilesional edema → transient deficits
• Hemorrhage along the trajectory
• Incomplete ablation
• Thermal injury to adjacent structures

In a Narrative review Gammel et al. from the Department of Neurosurgery, Virginia Commonwealth University Health System ¹⁾ review the history and physics of Laser Interstitial Thermal Therapy (LITT), discuss pioneering cases which pushed the boundaries of this therapy, and seminal trials which have explored its efficacy in treating brain metastasis and radiation necrosis.”

This is a narrative-driven, non-systematic overview that lacks methodological rigor. No inclusion/exclusion criteria, no PRISMA structure, no risk of bias assessment — it is, effectively, a personal essay in academic clothing.

The tone is techno-evangelical. Risks, limitations, and uncertainties of LITT are glossed over. Benefits are overstated. This reads more like a sponsored white paper than an objective academic review.

The review cherry-picks success stories and uncontrolled case series without critical appraisal. No comparative tables, no forest plots, no quantification of heterogeneity. Level IV evidence is treated as if it were Level I.

Major complications such as:

• Incomplete ablation
• Radiation necrosis mimicking recurrence
• Thermal damage to eloquent cortex
• Procedure-related hemorrhage

are either ignored or trivialized. This omission is clinically irresponsible.

Given the commercial landscape of LITT (Visualase®, NeuroBlate®), the absence of disclosure or critical appraisal of industry involvement is alarming. This raises the concern of undisclosed academic marketing.

Rather than critically evaluating where LITT fits within neuro-oncology workflows, the article positions the technique as a cure-all. No discussion of comparative effectiveness, cost-efficiency, or real-world constraints. This is technical maximalism repackaged as evidence-based innovation.

This review offers little more than a decorative, uncritical tribute to LITT. It fails to define success, ignores risks, and lacks scientific balance. Clinicians looking for guidance will find a choreographed celebration of technology, not a critical assessment. LITT deserves better scholarship — and so do our patients.