Does the Thermal Damage Estimate Correlate With the Magnetic Resonance Imaging Predicted Ablation Size After Laser Interstitial Thermal Therapy?

Patel, Nitesh V; Frenchu, Kiersten; Danish, Shabbar F.

doi:10.1093/ons/opx191

Cited by 20 publications

(25 citation statements)

References 14 publications

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“…17 This conclusion was further supported in a study that evaluated whether the TDE correlates with ablative area seen on postoperative MRI in perfused intracranial pathologies, once again finding that the TDE is in fact an accurate and reliable measure of ablative area. 23 Based on these studies, we can be confident that the findings reported within this study are based on consistent and reliable data.…”

Section: Discussionsupporting

confidence: 62%

Ablation dynamics of subsequent thermal doses delivered to previously heat-damaged tissue during magnetic resonance–guided laser-induced thermal therapy

Munier¹,

Hargreaves²,

Patel³

et al. 2019

Journal of Neurosurgery

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OBJECTIVEIntraoperative dynamics of magnetic resonance–guided laser-induced thermal therapy (MRgLITT) have been previously characterized for ablations of naive tissue. However, most treatment sessions require the delivery of multiple doses, and little is known about the ablation dynamics when additional doses are applied to heat-damaged tissue. This study investigated the differences in ablation dynamics between naive versus damaged tissue.METHODSThe authors examined 168 ablations from 60 patients across various surgical indications. All ablations were performed using the Visualase MRI-guided laser ablation system (Medtronic), which employs a 980-nm diffusing tip diode laser. Cases with multiple topographically overlapping doses with constant power were selected for this study. Single-dose intraoperative thermal damage was used to calculate ablation rate based on the thermal damage estimate (TDE) of the maximum area of ablation achieved (TDEmax) and the total duration of ablation (tmax). We compared ablation rates of naive undamaged tissue and damaged tissue exposed to subsequent thermal doses following an initial ablation.RESULTSTDEmax was significantly decreased in subsequent ablations compared to the preceding ablation (initial ablation 227.8 ± 17.7 mm2, second ablation 164.1 ± 21.5 mm2, third ablation 124.3 ± 11.2 mm2; p = < 0.001). The ablation rate of subsequent thermal doses delivered to previously damaged tissue was significantly decreased compared to the ablation rate of naive tissue (initial ablation 2.703 mm2/sec; second ablation 1.559 mm2/sec; third ablation 1.237 mm2/sec; fourth ablation 1.076 mm/sec; p = < 0.001). A negative correlation was found between TDEmax and percentage of overlap in a subsequent ablation with previously damaged tissue (r = −0.164; p < 0.02).CONCLUSIONSAblation of previously ablated tissue results in a reduced ablation rate and reduced TDEmax. Additionally, each successive thermal dose in a series of sequential ablations results in a decreased ablation rate relative to that of the preceding ablation. In the absence of a change in power, operators should anticipate a possible reduction in TDE when ablating partially damaged tissue for a similar amount of time compared to the preceding ablation.

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Section: Discussionsupporting

confidence: 62%

Ablation dynamics of subsequent thermal doses delivered to previously heat-damaged tissue during magnetic resonance–guided laser-induced thermal therapy

Munier¹,

Hargreaves²,

Patel³

et al. 2019

Journal of Neurosurgery

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“…The mean energy used for ablation was 2.59 kJ for tubers and 1.70 kJ for FCD. Limited reports have sought to elucidate the thermodynamics of brain tissue in response to the varied energy of ablation, 26,28,29,35 but there is no normative data on the required amount of energy to ablate tissues, so surgeons must instead rely on the thermal damage estimate (TDE) on the Visualase workstation. 8,17,23 Our ablation procedures averaged 222.75 minutes (range 179-252 minutes).…”

Section: Discussionmentioning

confidence: 99%

Early outcomes of stereoelectroencephalography followed by MR-guided laser interstitial thermal therapy: a paradigm for minimally invasive epilepsy surgery

Cobourn¹,

Fayed²,

Keating³

et al. 2018

Neurosurgical Focus

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OBJECTIVEStereoelectroencephalography (sEEG) and MR-guided laser interstitial thermal therapy (MRgLITT) have both emerged as minimally invasive alternatives to open surgery for the localization and treatment of medically refractory lesional epilepsy. Although some data are available about the use of these procedures individually, reports are almost nonexistent on their use in conjunction. The authors’ aim was to report early outcomes regarding efficacy and safety of sEEG followed by MRgLITT for localization and ablation of seizure foci in the pediatric population with medically refractory lesional epilepsy.METHODSA single-center retrospective review of pediatric patients who underwent sEEG followed by MRgLITT procedures was performed. Demographic, intraoperative, and outcome data were compiled and analyzed.RESULTSFour pediatric patients with 9 total lesions underwent sEEG followed by MRgLITT procedures between January and September 2017. The mean age at surgery was 10.75 (range 2–21) years. Two patients had tuberous sclerosis and 2 had focal cortical dysplasia. Methods of stereotaxy consisted of BrainLab VarioGuide and ROSA robotic guidance, with successful localization of seizure foci in all cases. The sEEG procedure length averaged 153 (range 67–235) minutes, with a mean of 6 (range 4–8) electrodes and 56 (range 18–84) contacts per patient. The MRgLITT procedure length averaged 223 (range 179–252) minutes. The mean duration of monitoring was 6 (range 4–8) days, and the mean total hospital stay was 8 (range 5–11) days. Over a mean follow-up duration of 9.3 (range 5.1–16) months, 3 patients were seizure free (Engel class I, 75%), and 1 patient saw significant improvement in seizure frequency (Engel class II, 25%). There were no complications.CONCLUSIONSThese early data demonstrate that sEEG followed by MRgLITT can be used safely and effectively to localize and ablate epileptogenic foci in a minimally invasive paradigm for treatment of medically refractory lesional epilepsy in pediatric populations. Continued collection of data with extended follow-up is needed.

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“…Furthermore, structures with internal flow, such as vascular and CSF spaces, act as heat sinks and enable focal ablation without damage to adjacent normal brain tissue [4][5][6]. The validity of the Arrhenius model as a reliable predictor of the ablation zone has been established in several studies [7][8][9]. However, the tissue response to ablation can be variable, particularly in heterogenous structures [10,11].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for the Treatment of Nonlesional Insular Epilepsy in Pediatric Patients: Technical Considerations

et al. 2020

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Introduction: The insula presents anatomic challenges to surgical exploration and intervention. Open neurosurgical intervention is associated with high rates of complications despite improved seizure control. Minimally invasive techniques using novel energy delivery methods have gained popularity due to their relative safety and ability to overcome access-related barriers. The goal of this paper is to present an operative technical report and methodological considerations on the application of magnetic resonanceguided laser interstitial thermal therapy (MRgLITT) for the treatment of nonlesional, medically refractory, insular epilepsy in pediatric patients. Methods: Visualase laser probe(s) were implanted using ROSA robotic stereotactic guidance into the insula using a parasagittal trajectory. After confirmation of placement using intraoperative MRI, thermal energy was delivered under real-time MR guidance. Laser wire pullback was performed when the initial dose of thermal energy was insufficient to ablate the target in its entirety. Thermal ablation within the intended target was confirmed using gadolinium-enhanced brain MRI. Following removal of laser wires, a final T1-weighted axial brain MRI was performed to confirm no evidence of hemorrhage. Results: Three patients underwent MRgLITT of nonlesional insular epilepsy over an 11-month period. The epileptogenic focus was localized to the insula using stereoelectroencephalography. The anterior and middle portions of the insula were accessed using a parasagittal trajectory. Laser ablation was performed for up to 3 min using an output of 10.5 W. No complications were encountered, and all patients were discharged within 24 h after the surgery. At the most recent follow-up, all patients had an Engel I outcome without any new neurologic deficits. Conclusion: This small cohort shows that insular ablation can be achieved safely with promising seizure outcomes in the short term.

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Does the Thermal Damage Estimate Correlate With the Magnetic Resonance Imaging Predicted Ablation Size After Laser Interstitial Thermal Therapy?

Abstract: The TDE is an accurate and reliable measure of ablated area in LITT in human cases as assessed on postoperative MRI. Future studies should be larger and assess reliability of the TDE when multiple lasers and planes are used.

Cited by 20 publications

References 14 publications

Ablation dynamics of subsequent thermal doses delivered to previously heat-damaged tissue during magnetic resonance–guided laser-induced thermal therapy

Ablation dynamics of subsequent thermal doses delivered to previously heat-damaged tissue during magnetic resonance–guided laser-induced thermal therapy

Early outcomes of stereoelectroencephalography followed by MR-guided laser interstitial thermal therapy: a paradigm for minimally invasive epilepsy surgery

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for the Treatment of Nonlesional Insular Epilepsy in Pediatric Patients: Technical Considerations

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