A pilot study for clinical feasibility of the near-harmonic 2D referenceless PRFS thermometry in liver under free breathing using MR-guided LITT ablation data

• Published in: International journal of hyperthermia Vol. 28; no. 3; pp. 250 - 266
• Main Authors: Kickhefel, Antje, Rosenberg, Christian, Roland, Jörg, Viallon, Magalie, Gross, Patrick, Schick, Fritz, Hosten, Norbert, Salomir, Rares
• Format: Journal Article
• Language: English
• Published: England Informa UK, Ltd 01.05.2012; Taylor & Francis
• Subjects: Aged; Breast Neoplasms - therapy; Colorectal Neoplasms - secondary; Colorectal Neoplasms - therapy; Female; Humans; Hyperthermia, Induced - methods; intervention; Laser Therapy; Liver - surgery; Magnetic Resonance Spectroscopy; Male; Middle Aged; Models, Theoretical; motion robust; Phantoms, Imaging; Pilot Projects; proton resonance frequency shift; Rectal Neoplasms - therapy; referenceless; Respiration; Stomach Neoplasms - therapy; Thermography - methods; thermometry
• DOI: 10.3109/02656736.2012.670834
• ISSN: 0265-6736

Objectives: The conventional implementations of proton resonance frequency shift (PRFS) magnetic resonance thermometry (MRT) require the subtraction of single or multiple temporal references, a motion sensitive critical feature. A pilot study was conducted here to investigate the clinical feasibility of near-harmonic two-dimensional (2D) referenceless PRFS MRT, using patient data from MR-guided laser ablation of liver malignancies. Methods: PRFS MRT with respiratory-triggered multi-slice gradient-recalled (GRE) acquisition was performed under free breathing in six patients. The precision of the novel referenceless MRT was compared with the reference phase subtraction. Coupling the referenceless MRT with a model-based, real-time compatible regularisation algorithm was also investigated. Results: The precision of MRT was improved by a factor of 3.3 when using the referenceless method as compared to the reference phase subtraction. The approach combining referenceless PRFS MRT and model-based regularisation yielded an estimated precision of 0.7° to 2.1°C, resulting in millimetre-range agreement between the calculated thermal dose and the 24 h post-treatment unperfused regions in liver. Conclusions: The application of the near-harmonic 2D referenceless MRT method was feasible in a clinical scenario of MR-guided laser-induced thermal therapy (LITT) ablation in liver and permitted accurate prediction of the thermal lesion under free breathing in conscious patients, obviating the need for a controlled breathing under general anaesthesia.