Laser-induced Thermal Therapy Research Articles

Outcomes following minimally invasive imagine-guided percutaneous ablation of adrenal glands.

Whilst surgery represents the gold standard for the treatment of adrenal primary malignant tumors, metastatic involvement of the adrenal glands is generally approached conservatively; however, surgery for local control has been controversial, and several reports have described the utility of surgical removal in terms of prolonged survival in selected patients. Different techniques, including radiofrequency ablation (RFA), microwave ablation (MWA), laser induced thermal therapy (LITT), cryoablation (CRA), and chemical ablation, are employed in percutaneous image-guided ablation for primary and metastatic malignancies of the adrenal glands, in case of patients with multiple comorbidities or who refuse surgery. Technical success, clinical success and safety were analysed and discussed in this systematic review. Tumor size was found a significant determinant for local disease control; histology of the primary malignancy and coexistence of tumor elsewhere were correlated with prognosis. These procedures resulted to be feasible and safe, with hypertensive crisis representing the most common complication. Although there is lack of evidence in the literature concerning outcomes compared with surgery, percutaneous ablation may represent a useful therapeutic option for controlling unresectable adrenal metastases, offering patients opportunities for improved survival.

Осложнение лазер-индуцированной термотерапии кисты Бейкера

Interventional laser-induced thermal therapy (LITT) is an emerging technique to treat popliteal synovial cysts. The goal of LITT is coagulation and subsequent obliteration of inosculation and cystic cavity under local tumescent anesthesia. Ultrasound is an imaging method used for LITT. Analyzing the results of the use of laser obliteration of Baker's cyst, the authors concluded that obliteration of solely the cystic popliteal cavity can provide persistent recovery. As expected, in any invasive procedure, there are some procedure-related adverse events or complications.

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

Intraoperative 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. The 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. TDEmax 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). Ablation 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.

Magnetic Resonance-Guided Laser-Induced Thermal Therapy for the Treatment of Progressive Enhancing Inflammatory Reactions Following Stereotactic Radiosurgery, or PEIRs, for Metastatic Brain Disease.

In patients who have previously undergone maximum radiation for metastatic brain tumors, a progressive enhancing inflammatory reaction (PEIR) that represents either tumor recurrence or radiation necrosis, or a combination of both, can occur. Magnetic resonance-guided laser-induced thermal therapy (LITT) offers a minimally invasive treatment option for this problem. To report our single-center experience using LITT to treat PEIRs after radiosurgery for brain metastases. Patients with progressive, enhancing reactions at the site of prior radiosurgery for metastatic brain tumors and who had a Karnofsky performance status of≥70 were eligible for LITT. The primary endpoint was local control. Secondary end points included dexamethasone use and procedure-related complications. Between 2010 and 2017, 59 patients who underwent 74 LITT procedures for 74 PEIRs met inclusion criteria. The mean pre-LITT PEIR size measured 3.4±0.4 cm3. At a median follow-up of 44.6 wk post-LITT, the local control rate was 83.1%. Most patients were weaned off steroids post-LITT. Patients experiencing a post-LITT complication were more likely to remain on steroids indefinitely. The rate of new permanent neurological deficit was 3.4%. LITT is an effective treatment for local control of PEIRs after radiosurgery for metastatic brain disease. When possible, we recommend offering LITT once PEIRs are identified and prior to the initiation of high-dose steroids for symptom relief.

Probing deep tissues with laser-induced thermotherapy using near-infrared light.

Optically tunable gold nanoparticles have been widely used in research with near-infrared light as a means to enhance laser-induced thermal therapy since it capitalizes on nanoparticles' plasmonic heating properties. There have been several studies published on numerical models replicating this therapy in such conditions. However, there are several limitations on some of the models which can render the model unfaithful to therapy simulations. In this paper, two techniques of simulating laser-induced thermal therapy with a high-absorbing localized region of interest inside a phantom are compared. To validate these models, we conducted an experiment of an agar-agar phantom with an inclusion reproducing it with both models. The phantom was optically characterized by absorption and total attenuation. The first model is based on the macroperspective solution of the radiative transfer equation given by the diffusion equation, which is then coupled with the Pennes bioheat equation to obtain the temperature. The second is a Monte Carlo model that considers a stochastic solution of the same equation and is also considered as input to the Pennes bioheat transfer equation which is then computed. The Monte Carlo is in good agreement with the experimental data having an average percentage difference of 4.5% and a correlation factor of 0.98, while the diffusion method comparison with experimental data is 61% and 0.95 respectively. The optical characterization of the phantom and its inclusion were also validated indirectly since the Monte Carlo, which used those parameters, was also validated. While knowing the temperature in all points inside a body during photothermal therapy is important, one has to be mindful of the model which fits the conditions and properties. There are several reasons to justify the discrepancy of the diffusion method: low-scattering conditions, absorption, and reduced scattering are comparable. The error bars that are normally associated when characterizing an optical phantom can justify also a part of that uncertainty. For low-size tumors in depth, one may have to increase the light dosage in photothermal therapies to have a more effective treatment.

Assessment of Optimal Imaging Protocol Sequences After Laser-Induced Thermal Therapy for Intracranial Tumors.

Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is a novel, minimally invasive method currently being used to treat a wide range of intracranial pathologies. No accepted guidelines exist on what the appropriate magnetic resonance imaging (MRI) sequences are for evaluating short-term postablation changes, especially when patients are not able to receive gadolinium. To evaluate which MRI sequences provide the greatest inter-rater reliability and least amount of variability in assessment of ablation volume after MRgLITT for intracranial neoplasms. Twenty patients who received MRgLITT were included. Three raters calculated volumetric measurements on postprocedural axial spoiled gradient recalled (SPGR), fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and gradient echo (GRE) sequences. Measured volumes were analyzed using intraclass correlation to determine which protocol had the most concordance among the 3 raters. Postcontrast SPGR sequences were most concordant in our study, with an intraclass correlation of 0.981. DWI was the next-most concordant imaging sequence with an intraclass correlation of 0.958. The least concordant were GRE (0.895) and FLAIR (0.866) images. SPGR was also the least variable and had the most consistent volume ratings compared to the other sequences. This study is the first to evaluate the inter-rater reliability of different MRI sequence protocols in the context of post-MRgLITT volumetric evaluation. SPGR postcontrast images facilitate the greatest interobserver concordance when characterizing post-MRgLITT tumor appearance and volumetrics, with DWI ranked second. Based on our findings, SPGR sequences are likely to yield the highest degree of concordance in post-MRgLITT lesion evaluation. When gadolinium cannot be given, DWI should provide the next most reliable estimation.

302 Corticosteroid Use and Its Relation to Postoperative Edema in Magnetic Resonance-Guided Laser-Induced Thermal Therapy for Recurrent Metastatic Brain Tumors

302 Corticosteroid Use and Its Relation to Postoperative Edema in Magnetic Resonance-Guided Laser-Induced Thermal Therapy for Recurrent Metastatic Brain Tumors

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

Magnetic resonance guided laser induced thermal therapy (LITT) is a minimally invasive method to treat a wide range of intracranial pathologies. The Arrhenius model is used to generate a thermal damage estimate (TDE) predicting ablation extent. Evaluation and correlation of the TDE to magnetic resonance imaging (MRI)-estimated ablation extent in human cases. The Medtronic Visualase system (Medtronic Inc, Dublin, Ireland) was utilized. Postablation axial T1-contrast enhanced images were acquired and intraoperative TDE image was obtained from the Visualase console. OsiriX DICOM Viewer (Pixmeo Inc, Bernex, Switzerland) was utilized to calculate cross-sectional area on MRI. ImageJ (National Institutes of Health, Bethesda, Maryland) was utilized for TDE area. Two blinded raters performed all measures. Statistical testing included Pearson correlation and the Student's t-test. Twenty-two cases including tumor and epilepsy were evaluated. Average MRI predicted tumor ablation area was 4.72 ± 2.22 cm2 and average predicted epilepsy ablation area was 4.12 ± 1.89 cm2. Average tumor TDE was 4.02 ± 1.95 cm2 and average epilepsy TDE was 4.36 ± 2.21 cm2. Rater 1's ablation areas and TDEs correlated with r = 0.89 (P < .0001) and no significant difference (P > .5). Rater 2's ablation areas and TDEs correlated with r = 0.91 (P < .0001) and no significant difference (P > .7). Rater 1 vs Rater 2 showed a strong correlation for TDE (r = 0.98, P < .000001) and ablation area (r = 0.96, P < .0001) and no significant difference (P > .5). 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.

Image-guided, minimally invasive surgery and other local therapeutic procedures for primary liver tumors

The incidence of primary liver tumors is rising. Modern minimally invasive, image-guided procedures offer apotentially curative therapy option. The aim of this study was to evaluate the multitude of image-guided minimally invasive procedures concerning their evidence-based effect on local tumor control and overall survival. Asystematic search of MEDLINE focused on hepatocellular cancer, minimally invasive treatment, local ablative therapy, therapeutic stratification and comparative studies was performed. The level of evidence varied greatly depending on the procedure used. The highest quality evidence including prospective randomized studies was found for radiofrequency ablation (RFA) of hepatocellular cancer. The RFA is superior with respect to local tumor control and overall survival in comparison to other ablative procedures. Prospective randomized studies comparing surgery and RFA showed diverging and contradictory results. Microwave ablation and robotic stereotactic irradiation showed sufficient potential in retrospective studies in comparison to RFA and surgery in order to confirm the techniques in randomized studies. There is only anecdotal evidence concerning high intensity focused ultrasound (HIFU) and irreversible electroporation. Percutaneous ethanol injection(PEI), cryoablation and laser-induced thermal therapy (LITT) were inferior techniques to RFA in most studies. Minimally invasive resection and local ablative therapies based on structured imaging and image reporting can improve the prognosis of patients with hepatocellular cancer even in patients that exceed the BCLC0/A stage.

Laser-Induced Thermal Therapy in Neuro-Oncology: A Review.

Laser therapy has become an appealing treatment modality in neurosurgery. In this review, we report on the history, physics, surgical steps, indications and uses, and complications that have been reported to date. An extensive literature search was performed for laser interstitial thermal therapy (LITT) and laser therapy in the context of glial tumors, metastatic lesions, pediatric brain tumors, and radiation necrosis. Reported complications in each series also were reviewed. In the past decade, multiple studies have demonstrated the use, outcomes, and complications associated with LITT in neurosurgery. These same studies have consistently reported an overall benefit of LITT in cases in which traditional surgical approaches may be limited by the patient's clinical status, tumor location, or overall prognosis. However, there have been complications reported from local effects of thermal damage, technical error, and edema development. Increased experience has reduced complications and brought more promising results. With the advent of real-time monitoring and damage estimation, LITT has gained ground in the management of intracranial tumors. Larger scale trials must be performed to develop standard protocols to define specific indications for use. Further large clinical studies for LITT in non-oncologic cases are also of interest.

Experimental Comparison of Photothermal Conversion Efficiency of Gold Nanotriangle and Nanorod in Laser Induced Thermal Therapy.

An experimental comparison of the photothermal conversion efficiency (PCE) for gold nanotriangles (GNTs) and nanorods (GNRs) was carried out in the present work. The discrete dipole approximation method was applied to identify the spectral characteristic of GNTs and GNRs with different aspect ratios. On this basis, the PCE of GNTs and GNRs in photothermal therapy were compared theoretically. Afterwards, an in vitro experiment was adopted to investigate the thermal effect of porcine muscle induced by laser irradiation, with and without injected GNTs and GNRs. The influences of laser total power, nanoparticle concentration, and nanoparticle type were investigated. It was found that for the commonly-used wavelengths for photothermal therapy, the PCE of GNTs is higher than that of the GNRs. Furthermore, for GNRs loaded in tissue in vitro, high laser power and high concentration of nanoparticles leads to the degeneration and even carbonization of tissue. However, for the GNTs with the same situation (laser power, nanoparticle volume concentration, and heating time), it could lead to the tissue’s evaporation instead of carbonization.

Quantitative Volumetric Analysis Following Magnetic Resonance-Guided Laser Interstitial Thermal Ablation of Cerebellar Metastases.

Treating recurrent posterior fossa metastases after previous radiation therapy and surgical resection remains challenging. Magnetic resonance laser-induced thermal therapy (MR-LITT) is a promising treatment for recurrent lesions, but data on safety, efficacy, and postablation volume change in the posterior fossa are lacking. All patients with recurrent posterior fossa metastatic lesions treated with MR-LITT by the senior neurosurgeon were included in the study. Preoperative and postoperative follow-up magnetic resonance imaging (MRI) studies were used to measure lesional and perilesional edema volume. These measurements were compared to calculate percent ablation volume. All patients' clinical examinations were followed closely. Four patients with recurrent cerebellar metastases were treated with MR-LITT. The average percent lesion ablated was 97.1% (range, 88.2%-100%). The average preoperative lesion volume was 3.3 cm3 (range, 1.1-7.2 cm3), and the average final postoperative volume was 3.8 cm3 (range, 0.5-7.6 cm3). Lesion volume increased to maximum volume on postoperative day 1, with an average increase of 486.9%. The extrapolated average time for the lesion to shrink to below the initial size was 294.5 days. There was a trend toward a decrease in average edema volume from the preoperative MRI of 17.8 cm3 to final postoperative follow-up MRI of 3.4 cm3 (P= 0.0952). No postoperative hydrocephalus or complications occurred. This pilot study shows that LITT appears to be a safe and promising treatment for recurrent posterior fossa metastatic lesions up to 7.2 cm3. Further randomized controlled studies are warranted to further characterize the long-term efficacy of this therapy.

Effects of variable power on tissue ablation dynamics during magnetic resonance-guided laser-induced thermal therapy with the Visualase system

Purpose: Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is a minimally invasive procedure used to treat various intracranial pathologies. This study investigated the effects of variable power on maximal estimated thermal damage during ablation and duration required to reach maximal ablation.Materials/Methods: All ablations were performed using the Visualase Thermal Therapy System (Medtronic Inc., Minneapolis, Minnesota), which uses a 980 nm diffusing tip diode laser. Cases were stratified into low, medium and high power. Maximal thermal damage estimate (TDEmax) achieved in a single plane and time to reach maximal damage (ttdemax) were measured and compared between groups using a 2×3 Fixed Factor Analysis of Covariance. Ablation area change for cases in which an initial thermal dose was followed by a subsequent dose, with increased power, was also assessed.Results: We used real-time ablation data from 93 patients across various intracranial pathologies. ttdemax (mean ± SEM) decreased linearly as power increased (low: 139.2 ± 10.4 s, medium: 127.5 ± 4.3 s, high: 103.7 ± 5.8 s). In cases where a second thermal dose was delivered at higher power, the TDE expanded an average of 51.4 mm2 beyond the initial TDE generated by the first ablation, with the second ablation approaching TDEmax at a higher rate than the initial ablation.Conclusion: Increased power results in a larger TDEmax and an increased ablation rate. In cases where an initial thermal dose does not fully ablate the target lesion, a second ablation at higher power can increase the area of ablation with an increased ablation rate.

A methodology for thermal dose model parameter development using perioperative MRI

Post-treatment imaging is the principal method for evaluating thermal lesions following image-guided thermal ablation procedures. While real-time temperature feedback using magnetic resonance temperature imaging (MRTI) is a complementary tool that can be used to optimise lesion size throughout the procedure, a thermal dose model is needed to convert temperature–time histories to estimates of thermal damage. However, existing models rely on empirical parameters derived from laboratory experiments that are not direct indicators of post-treatment radiologic appearance. In this work, we investigate a technique that uses perioperative MR data to find novel thermal dose model parameters that are tailored to the appearance of the thermal lesion on post-treatment contrast-enhanced imaging. Perioperative MR data were analysed for five patients receiving magnetic resonance-guided laser-induced thermal therapy (MRgLITT) for brain metastases. The characteristic enhancing ring was manually segmented on post-treatment T1-weighted imaging and registered into the MRTI geometry. Post-treatment appearance was modelled using a coupled Arrhenius-logistic model and non-linear optimisation techniques were used to find the maximum-likelihood kinetic parameters and dose thresholds that characterise the inner and outer boundary of the enhancing ring. The parameter values and thresholds were consistent with previous investigations, while the average difference between the predicted and segmented boundaries was on the order of one pixel (1 mm). The areas predicted using the optimised model parameters were also within 1 mm of those predicted by clinically utilised dose models. This technique makes clinically acquired data available for investigating new thermal dose model parameters driven by clinically relevant endpoints.

Image-guided thermal ablation with MR-based thermometry.

Thermal ablation techniques such as radiofrequency, microwave, high intensity focused ultrasound (HIFU) and laser have been used as minimally invasive strategies for the treatment of variety of cancers. MR thermometry methods are readily available for monitoring thermal distribution and deposition in real time, leading to decrease of incidents of normal tissue damage around targeted lesion. HIFU and laser-induced thermal therapy (LITT) are the two widely accepted tumor ablation techniques because of their compatibility with MR systems. MRI provides multiple temperature dependent parameters for thermal imaging, such as signal intensity, T1, T2, diffusion coefficient, magnetization transfer, proton resonance frequency shift (PRFS, including phase imaging and spectroscopy) as well as frequency shift of temperature sensitive contrast agents. Absolute temperature mapping techniques, including both spectroscopic imaging using metabolites as a reference and phase imaging using fat as a reference, are immune to susceptibility effects and are not dependent on phase differences. These techniques are intrinsically more reliable than relative temperature measurement by phase mapping methods. If the limitation of low temporal and spatial resolution could be overcome, these methods may be preferred for MR-guided thermal ablation systems. As of today, the most popular MR thermal imaging method applied in tumor thermal ablation surgery is, however, still PRFS based phase mapping technique, which only provides relative temperature change and is prone to motion artifacts.

Referenceless magnetic resonance temperature imaging using Gaussian process modeling

During magnetic resonance (MR)-guided thermal therapies, water proton resonance frequency shift (PRFS)-based MR temperature imaging can quantitatively monitor tissue temperature changes. It is widely known that the PRFS technique is easily perturbed by tissue motion, tissue susceptibility changes, magnetic field drift, and modality-dependent applicator-induced artifacts. Here, a referenceless Gaussian process modeling (GPM)-based estimation of the PRFS is investigated as a methodology to mitigate unwanted background field changes. The GPM offers a complementary trade-off between data fitting and smoothing and allows prior information to be used. The end result being the GPM provides a full probabilistic prediction and an estimate of the uncertainty. GPM was employed to estimate the covariance between the spatial position and MR phase measurements. The mean and variance provided by the statistical model extrapolated background phase values from nonheated neighboring voxels used to train the model. MR phase predictions in the heating ROI are computed using the spatial coordinates as the test input. The method is demonstrated in ex vivo rabbit liver tissue during focused ultrasound heating with manually introduced perturbations (n = 6) and in vivo during laser-induced interstitial thermal therapy to treat the human brain (n = 1) and liver (n = 1). Temperature maps estimated using the GPM referenceless method demonstrated a RMS error of <0.8°C with artifact-induced reference-based MR thermometry during ex vivo heating using focused ultrasound. Nonheated surrounding areas were <0.5°C from the artifact-free MR measurements. The GPM referenceless MR temperature values and thermally damaged regions were within the 95% confidence interval during in vivo laser ablations. A new approach to estimation for referenceless PRFS temperature imaging is introduced that allows for an accurate probabilistic extrapolation of the background phase. The technique demonstrated reliable temperature estimates in the presence of the background phase changes and was demonstrated useful in the in vivo brain and liver ablation scenarios presented.

Lesion Optimization for Laser Ablation: Fluid Evacuation Prior to Laser-Induced Thermal Therapy

Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is a minimally invasive surgical procedure for ablating intracranial lesions. The presence of a fluid body can sequester thermal energy generated by the laser catheter, which compromises the performance of MRgLITT, resulting in suboptimal ablation of cystic lesions. We report our use of stereotactic fluid evacuation followed by MRgLITT in 2 patients with cystic brain tumors. This is the first report on lesion optimization by fluid aspiration before MRgLITT. Two cystic tumors in 2 patients were treated. In 1 patient, an external ventricular drain was placed stereotactically to allow drainage of cystic fluid 1 day before laser ablation. In the second patient, a stereotactic biopsy needle was used to aspirate the cystic fluid immediately before laser ablation. The remaining solid portions of the both tumors were ablated using the Visualase system. Both patients were followed clinically and radiologically after the procedures. Stereotactic placement of an external ventricular drain and a biopsy needle both successfully resulted in fluid evacuation. MRgLITT was performed without any complications in both patients after fluid evacuation. Both patients demonstrated clinical and radiologic improvement after the procedure. Cystic fluid evacuation is a promising strategy for optimizing intracranial cystic lesions for MRgLITT. This novel approach may broaden the utility of MRgLITT in the management of various technically demanding lesions.

Technological advances in pediatric epilepsy surgery: implications for tuberous sclerosis complex

In selected children with tuberous sclerosis complex, epilepsy surgery leads to seizure freedom or seizure reduction. The current standard involves a multimodal pre-surgical workup followed by invasive electrocorticographic monitoring and resective surgery. Recent insights in the disorder and novel technologies are changing the approach to pediatric epilepsy surgery in tuberous sclerosis complex. New evidence suggests tubers are poorly delineated, and epileptogenic activity may originate in the perituber tissue. Novel imaging modalities relevant to surgical planning include high-resolution MRI, α-methyl-l-tryptophan or fluorodeoxyglucose PET with diffusion tensor imaging. Advanced neurophysiological techniques have improved identification of the surgical target, including magnetoencephalography, electrical source imaging of high-density electroencephalograph data, and high-frequency oscillations in electrocorticography data. Simultaneously, novel surgical tools including stereo-electroencephalography and laser-induced thermal therapy have become available for children. This article reviews the literature in the light of these rapidly changing technologies.

Long-Term Follow-up of 25 Cases of Biopsy-Proven Radiation Necrosis or Post-Radiation Treatment Effect Treated With Magnetic Resonance-Guided Laser Interstitial Thermal Therapy.

Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is a minimally invasive surgical treatment for progressive neoplasms and post-radiation treatment effect (PRTE). To evaluate the radiographic response and efficacy of MRgLITT for biopsy-confirmed PRTE and the quality-of-life outcomes of patients following MRgLITT. We conducted a single-center retrospective study of radiographic responses and clinical outcomes of 25 patients with previously treated primary or secondary brain neoplasms (World Health Organization grades 4 [n = 8], 3 [n = 5], 2 [n = 5]) and metastatic brain tumors (n = 7). MRgLITT was applied directly following stereotactic needle biopsy confirming PRTE without any evidence of tumor presence. Mean overall survival times (months) for grades 4 and 3 and for metastatic brain tumors were 39.2 (standard error [SE], 7.6; 95% confidence interval [CI], 24.3-54.1), 29.1 (SE, 7.7; 95% CI, 14.0-44.2), and 55.9 (SE, 10.0; 95% CI, 36.3-75.4), respectively. Mean progression-free survival times after MRgLITT were 9.1 (SE, 3.6; 95% CI, 2.1-16.1), 8.5 (SE, 2.4; 95% CI, 3.9-13.2), and 11.4 (SE, 3.9; 95% CI, 3.8-19.0), respectively. Mean survival times after MRgLITT were 13.1 (SE, 2.3; 95% CI, 8.5-17.6), 12.2 (SE, 4.0; 95% CI, 4.4-20.0), and 19.2 (SE, 5.3; 95% CI, 8.9-29.6), respectively. The SF-36 indicated significant overall effects on mental health (P = .029) and vitality (P = .005). MRgLITT may be a viable option for patients with symptomatic advancing PRTE and is less invasive than open craniotomy. Although our results suggest a positive effect for MRgLITT on PRTE, prospective randomized trials with larger numbers of patients are needed to validate the study results. cRBV, relative cerebral blood volumeHIF1a, hypoxia-inducible factor 1aIMRT, intensity-modulated radiation therapyKPS, Karnofsky Performance StatusLITT, laser-induced thermal therapyMBT, metastatic brain tumorMRgLITT, magnetic resonance-guided laser-induced thermal therapyPRTE, post-radiation treatment effectSRS, stereotactic radiosurgeryVEGF, vascular endothelial growth factorWBXRT, whole brain radiation therapy.

Laser Interstitial Thermal Therapy Technology, Physics of Magnetic Resonance Imaging Thermometry, and Technical Considerations for Proper Catheter Placement During Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy.

MRg-LITT, magnetic resonance-guided laser-induced thermal therapyPAD, precision aiming device.