Francesco Giurazza1, Carlo Massaroni2, Sergio Silvestri2, Bruno Beomonte Zobel3, Emiliano Schena2. 1. Interventional Radiology Department, Cardarelli Hospital, Via Cardarelli 9, 80100, Naples, Italy. francescogiurazza@hotmail.it. 2. Measurement and Biomedical Instrumentation Lab, Università Campus Bio-Medico di Roma, Via A. Del Portillo 200, 00198, Rome, Italy. 3. Radiology Department, Università Campus Bio-Medico di Roma, Via A. Del Portillo 200, 00198, Rome, Italy.
Abstract
AIMS: Real-time monitoring of tissue temperature during percutaneous tumor ablation improves treatment efficacy, leading clinicians in adjustment of treatment settings. This study aims at assessing feasibility of ultrasound thermometry during laser ablation of biological tissue using a specific ultrasound imaging techniques based on elastography acoustic radiation force impulse (ARFI). METHODS: ARFI uses high-intensity focused ultrasound pulses to generate 'radiation force' in tissue; this provokes tissue displacements trackable using correlation-based ultrasound methods: the sensitivity of shear waves velocity is able to detect temperature changes. Experiments were carried out using a Nd:YAG laser (power: 5 W) in three non-perfused ex vivo pig livers. In each organ, a thermocouple was placed close to the applicator tip (distance range 1.5-2.5 cm) used to record a reference temperature. Positioning of laser applicator and thermocouple was eco-guided. The organ was scanned by an echography system equipped with ARFI; propagation velocity was measured in a region of interest of 1 × 0.5 cm located close to thermocouple, to investigate influence of tissue temperature on shear waves velocity. RESULTS: Shear wave velocity has a very low sensitivity to temperature up to 55-60 °C, and in all cases, velocity is < 5 m s-1; for temperature > 55-60 °C, velocity shows a steep increment. The system measures a value "over limit", meaning a velocity > 5 m s-1. CONCLUSIONS: Ultrasound thermometry during laser ablation of biological tissue based on elastography shows an abrupt output change at temperatures > 55-60 °C. This issue can have a relevant clinical impact, considering tumor necrosis when temperature crosses 55 °C to define the boundary of damaged volume.
AIMS: Real-time monitoring of tissue temperature during percutaneous tumor ablation improves treatment efficacy, leading clinicians in adjustment of treatment settings. This study aims at assessing feasibility of ultrasound thermometry during laser ablation of biological tissue using a specific ultrasound imaging techniques based on elastography acoustic radiation force impulse (ARFI). METHODS: ARFI uses high-intensity focused ultrasound pulses to generate 'radiation force' in tissue; this provokes tissue displacements trackable using correlation-based ultrasound methods: the sensitivity of shear waves velocity is able to detect temperature changes. Experiments were carried out using a Nd:YAG laser (power: 5 W) in three non-perfused ex vivo pig livers. In each organ, a thermocouple was placed close to the applicator tip (distance range 1.5-2.5 cm) used to record a reference temperature. Positioning of laser applicator and thermocouple was eco-guided. The organ was scanned by an echography system equipped with ARFI; propagation velocity was measured in a region of interest of 1 × 0.5 cm located close to thermocouple, to investigate influence of tissue temperature on shear waves velocity. RESULTS: Shear wave velocity has a very low sensitivity to temperature up to 55-60 °C, and in all cases, velocity is < 5 m s-1; for temperature > 55-60 °C, velocity shows a steep increment. The system measures a value "over limit", meaning a velocity > 5 m s-1. CONCLUSIONS: Ultrasound thermometry during laser ablation of biological tissue based on elastography shows an abrupt output change at temperatures > 55-60 °C. This issue can have a relevant clinical impact, considering tumor necrosis when temperature crosses 55 °C to define the boundary of damaged volume.
Authors: E Schena; P Saccomandi; F Giurazza; M A Caponero; L Mortato; F M Di Matteo; F Panzera; R Del Vescovo; B Beomonte Zobel; S Silvestri Journal: Phys Med Biol Date: 2013-07-31 Impact factor: 3.609
Authors: Cristina Felicani; Chiara De Molo; Horia Stefanescu; Fabio Conti; Elena Mazzotta; Veronica Gabusi; Elena Nardi; Antonio Maria Morselli-Labate; Pietro Andreone; Carla Serra Journal: J Ultrasound Date: 2018-05-22
Authors: A Mariani; W Kwiecinski; M Pernot; D Balvay; M Tanter; O Clement; C A Cuenod; F Zinzindohoue Journal: J Surg Res Date: 2014-01-04 Impact factor: 2.192
Authors: S Righi; E Fiorini; C De Molo; V Cipriano; F Cassani; L Muratori; M Lenzi; A M Morselli Labate; C Serra Journal: J Ultrasound Date: 2012-10-25
Authors: Tito Livraghi; Luigi Solbiati; M Franca Meloni; G Scott Gazelle; Elkan F Halpern; S Nahum Goldberg Journal: Radiology Date: 2003-02 Impact factor: 11.105