Quantitative, Multi-institutional Evaluation of MR Thermometry Accuracy for Deep-Pelvic MR-Hyperthermia Systems Operating in Multi-vendor MR-systems Using a New Anthropomorphic Phantom.

Curto Curto,Mulder Mulder,Lindner Lindner,Lamprecht Lamprecht,Schmidt Schmidt,Zips Zips,Van Holthe Van Holthe,Franckena Franckena,Fietkau Fietkau,Van Rhoon Van Rhoon,Peller Peller,Paulides Paulides,Bellizzi Bellizzi,Aklan Aklan,Mils Mils,Wessalowski Wessalowski

doi:10.3390/cancers11111709

Abstract

Clinical outcome of hyperthermia depends on the achieved target temperature, therefore target conformal heating is essential. Currently, invasive temperature probe measurements are the gold standard for temperature monitoring, however, they only provide limited sparse data. In contrast, magnetic resonance thermometry (MRT) provides unique capabilities to non-invasively measure the 3D-temperature. This study investigates MRT accuracy for MR-hyperthermia hybrid systems located at five European institutions while heating a centric or eccentric target in anthropomorphic phantoms with pelvic and spine structures. Scatter plots, root mean square error (RMSE) and Bland–Altman analysis were used to quantify accuracy of MRT compared to high resistance thermistor probe measurements. For all institutions, a linear relation between MRT and thermistor probes measurements was found with R2 (mean ± standard deviation) of 0.97 ± 0.03 and 0.97 ± 0.02, respectively for centric and eccentric heating targets. The RMSE was found to be 0.52 ± 0.31 °C and 0.30 ± 0.20 °C, respectively. The Bland-Altman evaluation showed a mean difference of 0.46 ± 0.20 °C and 0.13 ± 0.08 °C, respectively. This first multi-institutional evaluation of MR-hyperthermia hybrid systems indicates comparable device performance and good agreement between MRT and thermistor probes measurements. This forms the basis to standardize treatments in multi-institution studies of MR-guided hyperthermia and to elucidate thermal dose-effect relations.

Highlights

Hyperthermia is an emerging treatment modality for malignant cancer which is performed in conjunction with chemotherapy and/or radiotherapy [1,2]
Minor differences in system responses can be seen at the 5 institutions, though the mean temperatures all agree within 1 ◦ C
This paper reports the results of the first international multi-institution quality assurance (QA) evaluation of hyperthermia systems in terms of magnetic resonance thermometry (MRT) accuracy

Summary

Introduction

Hyperthermia is an emerging treatment modality for malignant cancer which is performed in conjunction with chemotherapy and/or radiotherapy [1,2]. Clinical trials have reported thermal dose-effect relations [4,5,6,7,8,9] which strongly supports the need for measuring 3D-temperature combined with precise control of the generated heating pattern to apply the maximum achievable thermal dose. The implementation of quality assurance (QA) measures is essential to assure reliable system performance and to maximize the delivery of a specific thermal dose to achieve effective therapy. We previously reported that magnetic resonance thermometry (MRT) measurements using phantoms provide 3D-QA capabilities [10] to evaluate the performance of MR-compatible hyperthermia applicators. An elliptical cylindrical phantom containing bone structures was extensively used in the QA evaluation of the first BSD-2000-3D MR-compatible system (Pyrexar Medical Corp., Salt Lake City, UT, USA) [11]

Results

Discussion

Conclusion