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
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 R
2
(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