A model evaluation study for treatment planning of laser-induced thermal therapy

Fahrenholtz, Samuel; Moon, Tim Y.; Franco, Michael; Medina, David; Danish, Shabbar F.; Gowda, Ashok; Shetty, Anil; Maier, Florian; Hazle, John D.; Stafford, R. Jason; Warburton, Tim; Fuentes, David

doi:10.3109/02656736.2015.1055831

Cited by 20 publications

(27 citation statements)

References 62 publications

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“…However, the study also demonstrates nerve roots are less tolerant to the effects of IRE when compared to the spinal cord. Validation of this study in a large animal tumor model along with the development of computational tools (24) for treatment planning that could be used to estimate the electric field strength exposure of the tumor while simultaneously setting safety limits for exposure of the neural tissues (inverse treatment planning) is needed.…”

Section: Discussionmentioning

confidence: 99%

Irreversible Electroporation in the Epidural Space of the Porcine Spine: Effects on Adjacent Structures

Tam¹,

Figueira²,

Gagea³

et al. 2016

Radiology

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Purpose To determine the effects of irreversible electroporation (IRE) on the neural tissues following ablation in the epidural space of the porcine spine. Material and Methods The institutional animal care and use committee approved this study. With the IRE electrode positioned in the right lateral recess of the spinal epidural space, twenty CT-guided IRE ablations were performed using different applied voltages in four terminal animals. Histopathology of the neural tissues was assessed and used to select a voltage for a survival study. Sixteen CT-guided IRE ablations in the epidural space were performed using 667 V in four animals that were survived for 7-days. Clinical observation, magnetic resonance imaging (MRI) findings (obtained 6-hours post-IRE and pre-euthanasia),, histopathology, and simulated electric field strengths were assessed. A one-way analysis of variance (ANOVA) was used to compare the simulated electric field strength to histological findings. Results The mean distance between the IRE electrode and the spinal cord or nerve root was 1.71 ± 0.90 mm and 8.47 + 3.44 mm, respectively. There was no clinical evidence of paraplegia after IRE ablation. MRI and histopathology showed no neural-tissue lesions within the spinal cord; however, 31.2% (5/16) of nerve roots demonstrated moderate Wallerian degeneration in the survival group. Severity of histopathological injury in the survival group was not significantly related to either the simulated electric field strength or the distance between the IRE electrode and neural structure, (p >.05). Conclusions While the spinal cord appears resistant to the toxic effects of IRE, injury to the nerve roots may be a limiting factor for the use of IRE ablation in the epidural space.

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Section: Discussionmentioning

confidence: 99%

Irreversible Electroporation in the Epidural Space of the Porcine Spine: Effects on Adjacent Structures

Tam¹,

Figueira²,

Gagea³

et al. 2016

Radiology

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“…Most LITT studies have used a standard single echo (i.e., single contrast), 2D gradient recalled echo (GRE) pulse sequence with single slice acquisition times between 4.5 s to approximately 10 s, depending on resolution and field‐of‐view. To achieve larger coverage in the slice direction, Kickhefel et al used a multi‐slice 2D GRE to acquire three slices with 2.5 mm isotropic in‐plane resolution updated every 970 ms. 2D multi‐slice segmented echo planar imaging (EPI) pulse sequences, where multiple lines of k‐space are sampled after each RF excitation pulse, have allowed for between three to five slices to be imaged in between 4 and 6 s .…”

Section: Introductionmentioning

confidence: 99%

Improved MR thermometry for laser interstitial thermotherapy

Odéen

Parker

2019

Lasers Surg Med

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Objectives: To develop, test and evaluate improved 2D and 3D protocols for proton resonance frequency shift magnetic resonance temperature imaging (MRTI) of laser interstitial thermal therapy (LITT). The objective was to develop improved MRTI protocols in terms of temperature measurement precision and volume coverage compared to the 2D MRTI protocol currently used with a commercially available LITT system. Methods: Four different 2D protocols and four different 3D protocols were investigated. The 2D protocols used multi-echo readouts to prolong the total MR sampling time and hence the MRTI precision, without prolonging the total acquisition time. The 3D protocols provided volumetric thermometry by acquiring a slab of 12 contiguous slices in the same acquisition time as the 2D protocols. The study only considered readily available pulse sequences (Cartesian 2D and 3D gradient recalled echo and echo planar imaging [EPI]) and methods (partial Fourier and parallel imaging) to ensure wide availability and rapid clinical implementation across vendors and field strengths. In vivo volunteer studies were performed to investigate and compare MRTI precision and image quality. Phantom experiments with LITT heating were performed to investigate and compare MRTI precision and accuracy. Different coil setups were used in the in vivo studies to assess precision differences between using local (such as flex and head coils) and non-local (i.e., body coil) receive coils. Studies were performed at both 1.5 T and 3 T. Results: The improved 2D protocols provide up to a factor of two improvement in the MRTI precision in the same acquisition time, compared to the currently used clinical protocol. The 3D echo planar imaging protocols provide comparable precision as the currently used 2D clinical protocol, but over a substantially larger field of view, without increasing the acquisition time. As expected, local receive coils perform substantially better than the body coil, and 3 T provides better MRTI accuracy and precision than 1.5 T. 3D data can be zero-filled interpolated in all three dimensions (as opposed to just two dimensions for 2D data), reducing partial volume effects and measuring higher maximum temperature rises. Conclusions: With the presented protocols substantially improved MRTI precision (for 2D imaging) or greatly improved field of view coverage (for 3D imaging) can be achieved in the same acquisition time as the currently used protocol. Only widely available pulse sequences and acquisition methods were investigated, which should ensure quick translation to the clinic. Lasers Surg. Med. 51:286-300, 2019.

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“…Further work is needed in cross-validating our approach to evaluate the a priori prediction accuracy of our approach. Similar to our previous efforts with other modalities [54], independent calibration and validation datasets are needed to obtain population average model parameters for a priori prediction. Additional imaging methods are needed to complement the MR thermometry for validation of the location of the injected bolus of oily solvent and acid chloride.…”

Section: Discussionmentioning

confidence: 99%

Mathematical modeling of mass and energy transport for thermoembolization

Fuentes

Fahrenholtz

Guo

et al. 2020

International Journal of Hyperthermia

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Background: Thermoembolization presents a unique treatment alternative for patients diagnosed with hepatocellular carcinoma. The approach delivers a reagent that undergoes an exothermic chemical reaction and combines the benefits of embolic as well as thermal-and chemical-ablative therapy modalities. The target tissue and vascular bed are subjected to simultaneous hyperthermia, ischemia, and chemical denaturation in a single procedure. To guide optimal delivery, we developed a mathematical model for understanding the competing diffusive and convective effects observed in thermoembolization delivery protocols. Methods: A mixture theory formulation was used to mathematically model thermoembolization as chemically reacting transport of an electrophile, dichloroacetyl chloride (DCACl), within porous living tissue. Mass and energy transport of each relevant constituent are considered. Specifically, DCACl is injected into the vessels and exothermically reacts with water in the blood or tissue to form dichloroacetic acid and hydrochloric acid. Neutralization reactions are assumed instantaneous in this approach. We validated the mathematical model predictions of temperature using MR thermometry of the thermoembolization procedure performed in ex vivo kidney. Results: Mathematical modeling predictions of tissue death were highly dependent on the vascular geometry, injection pressure, and intrinsic amount of exothermic energy released from the chemical species, and were able to recapitulate the temperature distributions observed in MR thermometry. Conclusion: These efforts present a first step toward formalizing a mathematical model for thermoembolization and are promising for providing insight for delivery protocol optimization. While our approach captured the observed experimental temperature measurements, larger-scale experimental validation is needed to prioritize additional model complexity and fidelity.

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A model evaluation study for treatment planning of laser-induced thermal therapy

Cited by 20 publications

References 62 publications

Irreversible Electroporation in the Epidural Space of the Porcine Spine: Effects on Adjacent Structures

Irreversible Electroporation in the Epidural Space of the Porcine Spine: Effects on Adjacent Structures

Improved MR thermometry for laser interstitial thermotherapy

Mathematical modeling of mass and energy transport for thermoembolization

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