Does the real-time thermal damage estimate allow for estimation of tumor control after MRI-guided laser-induced thermal therapy? Initial experience with recurrent intracranial ependymomas

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>Although control of intracranial ependymomas is highly correlated with degree of resection, it is unknown if the same is true for MRI-guided laser-induced thermal therapy (MRgLITT). The authors report their experience with MRgLITT for ependymoma and examine the utility of the real-time thermal damage estimate (TDE), a recent software advance, with respect to completeness of ablation and impact on tumor control. To the authors' knowledge, this is the largest single-center experience utilizing MRgLITT for recurrent ependymomas.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Five tumors in 4 patients were treated with the Visualase Thermal Therapy System. Two tumors were treated similarly on recurrence. Ablation was performed using a 980-nm diode laser with a real-time image acquisition system. Single-plane TDEs were calculated and compared with the original lesion area to compute percentage area ablated (PAA). Volumetric analysis was performed, and percentage volume ablated (PVA) was estimated and correlated with the TDE. Tumor control was correlated with the TDE and volumetric data during treatment.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>Nine ablations were performed on 5 tumors, 2 of which had multiple recurrences. The average pretreatment lesion volume was 8.4 ± 6.3 cm<jats:sup>3</jats:sup>, and the average largest 2D area was 5.3 ± 2.7 cm<jats:sup>2</jats:sup>. The averaged TDE was 3.9 ± 2.1 cm<jats:sup>2</jats:sup>, average PAA was 80.1% ± 34.3%, and average PVA was 64.4% ± 23.5%. For subtotal ablations, average recurrence time was 4.4 ± 5.3 months; 1 adult case remains recurrence-free at 40 months. Using TDEs, the correlation between recurrence time and PAA was r = 0.93 (p = 0.01), and for PVA was r = 0.88 (p = 0.02). Furthermore, PVA and PAA were strongly correlated (r = 0.88, p = 0.02).</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Through using the PAA, the real-time TDE correlated with the volume of ablation in this initial investigation. Furthermore, the TDE and volumetric data corresponded to the level of tumor control, with time to recurrence dependent on ablation completeness. MRgLITT may have a role in the management of recurrent ependymomas, especially with recent software advances.</jats:p></jats:sec>

Laser application in neurosurgery

“…[ 103 ] Patel et al . [ 108 ] presented their initial experience of MRI-guided LITT for recurrent intracranial ependymomas in 9 ablations for 5 tumors. They reported the possibility of long-term control for these tumors; however, radical ablation is paramount because an incompletely ablated ependymoma will inevitably recur.…”

“…The topics covered include magnetic resonance (MR)-guided percutaneous ablation, anastomosis, therapeutic applications, and diagnostic applications [ Table 2 ]. [ 3 7 11 12 15 17 25 27 33 34 35 38 44 53 61 65 67 74 83 85 92 108 112 113 116 119 120 127 130 131 133 136 137 140 146 147 148 151 ]…”

Stereotactic Laser Ablation for Medically Intractable Epilepsy: The Next Generation of Minimally Invasive Epilepsy Surgery

“…Moreover, postoperative MRI showed that ablation lesions were consistent with preoperative planning to within 6 mm. Since then, several groups have used Visualase in the treatment of primary brain tumors (103–106), brain metastases, radiation necrosis (104, 107–109), spinal metastases (110), and other tumors outside the CNS, most notably prostate cancer (111, 112). NeuroBlate was first trialed in 10 patients with recurrent glioblastoma (90) and has since been used in patients with primary gliomas (89, 113), brain metastases (113, 114), and radiation necrosis (115, 116).…”

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

“…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].…”