Purpose: The aim of this study was to characterise changes in tissue volume during image guided microwave ablation in order to arrive at a more precise determination of the true ablation zone. Materials and methods: The effect of power (20–80 W) and time (1–10 min) on microwave-induced tissue contraction was experimentally evaluated in various-sized cubes of ex vivo liver (10–40mm± 2 mm) and muscle (20 and 40mm± 2 mm) embedded in agar phantoms (N¼119). Post-ablation linear and volumetric dimensions of the tissue cubes were measured and compared with pre-ablation dimensions. Subsequently, the process of tissue contraction was investigated dynamically during the ablation procedure through real-time Xray CT scanning. Results: Overall, substantial shrinkage of 52–74% of initial tissue volume was noted. The shrinkage was non-uniform over time and space, with observed asymmetry favouring the radial (23–43 % range) over the longitudinal (21–29%) direction. Algorithmic relationships for the shrinkage as a function of time were demonstrated. Furthermore, the smallest cubes showed more substantial and faster contraction (28–40% after 1 min), with more considerable volumetric shrinkage (410%) in muscle than in liver tissue. Additionally, CT imaging demonstrated initial expansion of the tissue volume, lasting in some cases up to 3 min during the microwave ablation procedure, prior to the contraction phenomenon. Conclusions: In addition to an asymmetric substantial shrinkage of the ablated tissue volume, an initial expansion phenomenon occurs during MW ablation. Thus, complex modifications of the tissue close to a radiating antenna will likely need to be taken into account for future methods of real-time ablation monitoring

Characterisation of tissue shrinkage during microwave thermal ablation / Farina, Laura; N., Weiss; Y., Nissenbaum; Cavagnaro, Marta; V., Lopresto; R., Pinto; N., Tosoratti; C., Amabile; S., Cassarino; S. N., Goldberg. - In: INTERNATIONAL JOURNAL OF HYPERTHERMIA. - ISSN 0265-6736. - STAMPA. - 30(7)(2014), pp. 419-428. [10.3109/02656736.2014.957250]

Characterisation of tissue shrinkage during microwave thermal ablation

FARINA, LAURA;CAVAGNARO, Marta;
2014

Abstract

Purpose: The aim of this study was to characterise changes in tissue volume during image guided microwave ablation in order to arrive at a more precise determination of the true ablation zone. Materials and methods: The effect of power (20–80 W) and time (1–10 min) on microwave-induced tissue contraction was experimentally evaluated in various-sized cubes of ex vivo liver (10–40mm± 2 mm) and muscle (20 and 40mm± 2 mm) embedded in agar phantoms (N¼119). Post-ablation linear and volumetric dimensions of the tissue cubes were measured and compared with pre-ablation dimensions. Subsequently, the process of tissue contraction was investigated dynamically during the ablation procedure through real-time Xray CT scanning. Results: Overall, substantial shrinkage of 52–74% of initial tissue volume was noted. The shrinkage was non-uniform over time and space, with observed asymmetry favouring the radial (23–43 % range) over the longitudinal (21–29%) direction. Algorithmic relationships for the shrinkage as a function of time were demonstrated. Furthermore, the smallest cubes showed more substantial and faster contraction (28–40% after 1 min), with more considerable volumetric shrinkage (410%) in muscle than in liver tissue. Additionally, CT imaging demonstrated initial expansion of the tissue volume, lasting in some cases up to 3 min during the microwave ablation procedure, prior to the contraction phenomenon. Conclusions: In addition to an asymmetric substantial shrinkage of the ablated tissue volume, an initial expansion phenomenon occurs during MW ablation. Thus, complex modifications of the tissue close to a radiating antenna will likely need to be taken into account for future methods of real-time ablation monitoring
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11573/708863
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