Evaluation and selection of anatomic sites for magnetic resonance imaging-guided mild hyperthermia therapy: a healthy volunteer study

Abstract

Respiration, cardiac, and digestive-related motion pose challenges to MR thermometry of the chest wall and bladder wall. The leg muscles had satisfactory temperature accuracy and precision per the chosen criteria. These results indicate that extremity locations may be preferable targets for MR-guided MHT using the existing MR thermometry technique.

MR Thermometry Accuracy and Prospective Imaging-Based Patient Selection in MR-Guided Hyperthermia Treatment for Locally Advanced Cervical Cancer

“…The receiver operating characteristic (ROC) curve was used to analyze how predictive each feature is for acceptable/reliable MR thermometry, and to determine the cut-off values [55,56]. MR thermometry was classified as acceptable for each treatment session (true-condition) when in-accuracy was equal or lower than 1 • C [57], and false otherwise. The area under the ROC curve (AUC) was used as a robust measure to evaluate the performance of the score classifier [58,59].…”

“…In addition, the 95% confidence interval was calculated for each feature and the p-value for the null hypothesis that the AUC is equal to 0.5 (random relation).For each treatment session, the accuracy of MR thermometry measurements (Equation ( 6)) provided the degree of closeness of the measured temperature change to the actual temperature change (i.e., intraluminal temperature) [48,61]. Given the importance of keeping the proper heating range, we consider the accuracy of ≤1 • C as suitable [48,57]. The temporal precision was determined by the variability of the spatial mean temperature in an ROI across all time points, shown in Equation (7).…”

Integrating Loco-Regional Hyperthermia Into the Current Oncology Practice: SWOT and TOWS Analyses

“…Non-invasive MR thermometry is now widely used for MR-guided HIFUbased thermal ablation procedures (241). The proton resonance frequency shift (PRFS) method measures relative temperature changes with a resolution of ±1 • C as validated for soft tissue sarcoma in the pelvis and lower extremities (105,242); noninvasive MR thermometry is increasingly used for monitoring moderate HT treatment, presently mainly at tumor sites with minimal motion artifacts (e.g., soft tissue sarcoma in extremities), as accuracy of PRFS can be lower in body regions with significant respiration, cardiac, or bowel organ motion artifacts (243)(244)(245). Model-based and other new MR thermometry FIGURE 4 | Upper panel: Moderate hyperthermia, with its ability to inhibit radiotherapy-induced DNA repair and its radiosensitizing effects on hypoxic tumor cells, has features akin to high linear energy transfer (LET) radiations.…”

Hyperthermia Treatment Planning Including Convective Flow in Cerebrospinal Fluid for Brain Tumour Hyperthermia Treatment Using a Novel Dedicated Paediatric Brain Applicator

“…The discussed brain hyperthermia applicators (including the Chalmers Hyperthermia Helmet) are all MR-compatible, so that, in principle, temperature may be monitored during treatment using MR thermometry. However, especially in a post-operative scenario with a large fluid-filled pocket, these measurements may be unreliable in and around the CSF-filled pocket due to motion artefacts; this is similar to MR-thermometry in and around the urinary bladder [73], for which an MR thermometry accuracy of 1.86 ± 1.20 °C has been reported [74]. Therefore, additional forms of treatment guidance would still be needed, such as numerical temperature simulation; if possible, supplemented with, preferably invasive, thermometry.…”