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Estimation of the Proton Resonance Frequency Coefficient in Agar-based Phantoms.
Filippou, Antria; Evripidou, Nikolas; Georgiou, Andreas; Nikolaou, Anastasia; Damianou, Christakis.
Afiliación
  • Filippou A; Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
  • Evripidou N; Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
  • Georgiou A; Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
  • Nikolaou A; Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
  • Damianou C; Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
J Med Phys ; 49(2): 167-180, 2024.
Article en En | MEDLINE | ID: mdl-39131424
ABSTRACT

Aim:

Agar-based phantoms are popular in high intensity focused ultrasound (HIFU) studies, with magnetic resonance imaging (MRI) preferred for guidance since it provides temperature monitoring by proton resonance frequency (PRF) shift magnetic resonance (MR) thermometry. MR thermometry monitoring depends on several factors, thus, herein, the PRF coefficient of agar phantoms was estimated. Materials and

Methods:

Seven phantoms were developed with varied agar (2, 4, or 6% w/v) or constant agar (6% w/v) and varied silica concentrations (2, 4, 6, or 8% w/v) to assess the effect of the concentration on the PRF coefficient. Each phantom was sonicated using varied acoustical power for a 30 s duration in both a laboratory setting and inside a 3T MRI scanner. PRF coefficients were estimated through linear trends between phase shift acquired using gradient sequences and thermocouple-based temperatures changes.

Results:

Linear regression (R 2 = 0.9707-0.9991) demonstrated a proportional dependency of phase shift with temperature change, resulting in PRF coefficients between -0.00336 ± 0.00029 and -0.00934 ± 0.00050 ppm/°C for the various phantom recipes. Weak negative linear correlations of the PRF coefficient were observed with increased agar. With silica concentrations, the negative linear correlation was strong. For all phantoms, calibrated PRF coefficients resulted in 1.01-3.01-fold higher temperature changes compared to the values calculated using a literature PRF coefficient.

Conclusions:

Phantoms developed with a 6% w/v agar concentration and doped with 0%-8% w/v silica best resemble tissue PRF coefficients and should be preferred in HIFU studies. The estimated PRF coefficients can result in enhanced MR thermometry monitoring and evaluation of HIFU protocols.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Med Phys Año: 2024 Tipo del documento: Article País de afiliación: Chipre Pais de publicación: India
Texto completo
Añadir a Mi BVS
Imprimir
XML
PubMed Links
Buscar en Google

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Med Phys Año: 2024 Tipo del documento: Article País de afiliación: Chipre Pais de publicación: India