Image-guided thermal ablation with MR-based thermometry

Zhu, Min; Sun, Ziqi; Ng, Chin K.

doi:10.21037/qims.2017.06.06

Cited by 77 publications

(80 citation statements)

References 80 publications

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“…The presence of an MR contrast agent can produce local susceptibility effects, confounding the estimated temperature measurement. 77,78 No discrepancies between MR thermometry and other methods of treatment assessment that were specific to the experimental arms were observed in this study. For the concentrations of Gd 2 O 3 employed in this study, the error in the temperature measurements would be less than 1°C based on data reported by Hijnen et al 77 However, these results refer to aqueous contrast agent and do not necessarily reflect the errors associated with the use of Gd 2 O 3 nanoparticles.…”

Section: Discussionmentioning

confidence: 62%

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MRI‐guided transurethral insonation of silica‐shell phase‐shift emulsions in the prostate with an advanced navigation platform

et al. 2018

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Purpose In this study, the efficacy of transurethral prostate ablation in the presence of silica‐shell ultrasound‐triggered phase‐shift emulsions (sUPEs) doped with MR contrast was evaluated. The influence of sUPEs on MR imaging assessment of the ablation zone was also investigated. Methods sUPEs were doped with a magnetic resonance (MR) contrast agent, Gd2O3, to assess ultrasound transition. Injections of saline (sham), saline and sUPEs alone, and saline and sUPEs with Optison microbubbles were performed under guidance of a prototype interventional MRI navigation platform in a healthy canine prostate. Treatment arms were evaluated for differences in lesion size, T1 contrast, and temperature. In addition, non‐perfused areas (NPAs) on dynamic contrast‐enhanced (DCE) MRI, 55°C isotherms, and areas of 240 cumulative equivalent minutes at 43°C (CEM43) dose or greater computed from MR thermometry were measured and correlated with ablated areas indicated by histology. Results For treatment arms including sUPEs, the computed correlation coefficients between the histological ablation zone and the NPA, 55°C isotherm, and 240 CEM43 area ranged from 0.96–0.99, 0.98–0.99, and 0.91–0.99, respectively. In the absence of sUPEs, the computed correlation coefficients between the histological ablation zone and the NPA, 55°C isotherm, and 240 CEM43 area were 0.69, 0.54, and 0.50, respectively. Across all treatment arms, the areas of thermal tissue damage and NPAs were not significantly different (P = 0.47). Areas denoted by 55°C isotherms and 240 CEM43 dose boundaries were significantly larger than the areas of thermal damage, again for all treatment arms (P = 0.009 and 0.003, respectively). No significant differences in lesion size, T1 contrast, or temperature were observed between any of the treatment arms (P > 0.0167). Lesions exhibiting thermal fixation on histological analysis were present in six of nine insonations involving sUPE injections and one of five insonations involving saline sham injections. Significantly larger areas (P = 0.002), higher temperatures (P = 0.004), and more frequent ring patterns of restricted diffusion on ex vivo diffusion‐weighted imaging (P = 0.005) were apparent in lesions with thermal fixation. Conclusions T1 contrast suggesting sUPE transition was not evident in sUPE treatment arms. The use of MR imaging metrics to predict prostate ablation was not diminished by the presence of sUPEs. Lesions generated in the presence of sUPEs exhibited more frequent thermal fixation, though there were no significant changes in the ablation areas when comparing arms with and without sUPEs. Thermal fixation corresponded to some qualitative imaging features.

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Section: Discussionmentioning

confidence: 62%

“…The presence of an MR contrast agent can produce local susceptibility effects, confounding the estimated temperature measurement . No discrepancies between MR thermometry and other methods of treatment assessment that were specific to the experimental arms were observed in this study.…”

Section: Discussionmentioning

confidence: 64%

MRI‐guided transurethral insonation of silica‐shell phase‐shift emulsions in the prostate with an advanced navigation platform

et al. 2018

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“…Fiber optic sensors for temperature monitoring have been developed to monitor the temperatures in several points without a significant increase of invasiveness . With the development of medical imaging technology, the temperatures in MWA can be noninvasively estimated from magnetic resonance imaging, computed tomography, ultrasound imaging, and infrared‐thermography, although these modalities have their own drawbacks . Therefore, it may be possible to measure the temperatures at a certain point simply and noninvasively in the future.…”

Section: Discussionmentioning

confidence: 99%

2450-MHz microwave ablation temperature simulation using temperature-dependence feedback of characteristic parameters

Gao

Wang

et al. 2018

Int J RF Microw Comput Aided Eng

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Temperature predictions of microwave ablation (MWA) are currently restricted by the specific temperature-dependent data of tissue characteristic parameters. To address this issue, a new parameter feedback method based on temperature simulations and single-thermometry measurements was presented. Experimental data of 2450-MHz microwave antenna was obtained from ex vivo porcine livers. A temperature distribution model was constructed, and the contributions of characteristic parameters were acquired by the sensitivity analysis method. Subsequently, parameter feedbacks were conducted based on a minimization of the errors between numerical data and single-thermometry measurements. The temperature distribution model was then optimized using the feedback parameters. Finally, temperature measurements were compared with simulation data to validate the accuracy of the model. According to the temperature distribution model with parameter feedback, the averages of maximum error, average error, as well as SD between the simulation temperatures and the measurements were 2.952, 1.323, and 0.852 C, respectively. The simulated and measured temperature changes were generally in good agreement. The proposed method can be useful in MWA temperature simulations to improve temperature prediction accuracy. K E Y W O R D S characteristic parameters, microwave ablation, parameter feedback, temperature distribution simulation 1 | INTRODUCTIONMicrowave ablation (MWA) has become an effective technique to treat liver tumors. 1 A microwave (MW) antenna is percutaneously inserted into the tumor to induce coagulation necrosis, thereby killing tumor cells in situ. 2 In the clinical MWA, 915-and 2450-MHz MWAs are usually used 3-5 to obtain desired thermal coagulation by constant powers such as 40, 50, and 60 W. Compared with surgical resections, MWA has fewer complications and minimally invasive advantages. [6][7][8][9] Many studies show that complete coagulation can occur instantly at least 55-60 C. [10][11][12] In the treatment of liver tumors, the zone with the temperature higher than 54 C is considered as thermal coagulation zone. 13 Although MWA has promising application prospects, temperature distributions are still difficult to predict and monitor precisely. Therefore, how to control ablation temperatures and coagulation zones has become a well-recognized challenge. 14 At present, a wide variety of simulation methods based on electromagnetic and bio-heat transfer equations have been proposed to predict complete temperature distributions induced by MW antenna. [15][16][17] The advantages of temperature simulations over the sparse data from the invasive thermometry are the possibility of generating three-dimensional (3D) temperature distributions. 18 However, the simulation precisions of temperature distributions have still not met the clinical requirements due to several factors such as interindividual differences, varying tissue characteristics and complicated bio-heat transfer mechanism. 19 Conventionally, the changes in characteristic para...

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“…There are numerous mechanisms by which contrast can be generated in MRI, and many of these mechanisms can be used to assess either relative or absolute temperature changes in tissue, with different sensitivity, spatial, and temporal resolution. 28,29 No other imaging modality is as sensitive to temperature change as is MRI, and MRI is currently used for thermometry to monitor temperatures during thermal ablation, 28 most commonly for laser-induced thermal therapy and MRgHIFU, but also for radiofrequency and microwave ablation. MR thermometry for cryoablation is currently being explored in research laboratories.…”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%