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

Abstract

The efficacy of a hyperthermia treatment depends on the delivery of well-controlled heating; hence, accurate temperature monitoring is essential for ensuring effective treatment. For deep pelvic hyperthermia, there are no comprehensive and systematic reports on MR thermometry. Moreover, data inclusion generally lacks objective selection criteria leading to a high probability of bias when comparing results. Herein, we studied whether imaging-based data inclusion predicts accuracy and could serve as a tool for prospective patient selection. The accuracy of the MR thermometry in patients with locally advanced cervical cancer was benchmarked against intraluminal temperature. We found that gastrointestinal air motion at the start of the treatment, quantified by the Jaccard similarity coefficient, was a good predictor for MR thermometry accuracy. The results for the group that was selected for low gastrointestinal air motion improved compared to the results for all patients by 50% (accuracy), 26% (precision), and 80% (bias). We found an average MR thermometry accuracy of 2.0 °C when all patients were considered and 1.0 °C for the selected group. These results serve as the basis for comprehensive benchmarking of novel technologies. The Jaccard similarity coefficient also has good potential to prospectively determine in which patients the MR thermometry will be valuable.

POD–Kalman filtering for improving noninvasive 3D temperature monitoring in MR‐guided hyperthermia

“…Several studies have shown that MR thermometry assessment in the pelvic region is challenging. 19,22,62 Our previous study showed that the amount of intestinal gas motion at the start of the treatment was an MR thermometry accuracy predictor and that a higher level of motion caused stronger susceptibility artifacts.Hence, patients with a high intestinal gas motion would not be amendable for reliable MR thermometry acquisition. 22 In the current study, three patient groups were defined according to the level of intestinal gas motion (Jaccard coefficient).…”

“…Figure 8 and Table 4 confirm the relation between MAE from filtered MR thermometry and the Jaccard coefficient since patients with higher Jaccard coefficients have a lower MAE. 22 Even though more motion TA B L E 3 MAE and SDE are expressed by the mean ± standard deviation. These were calculated for three different anatomical locations: V-vagina, R-Rectum, and B-Bladder.…”

“…Considering all intraluminal locations, the thermal mapping range was 8.5 cm ± 2.8 cm. Our previous study 22 showed that the Jaccard coefficient (Jaccard ≥ 0.91) between two baseline scans is predictive of MR thermometry accuracy. The Jaccard coefficient was used to quantify the level of intestinal gas motion and, consequently, the resulting susceptibilities artifacts.…”

“…11 Our recent work confirmed that intestinal gas motion caused strong susceptibilities artifacts in MR thermometry, and that its quantification prior to treatment predicts MR thermometry accuracy during treatment. 22 Moreover, the number of MR thermometry updates is restricted during treatment due to the water circulation through the water bolus surrounding the patient. Because water circulation creates significant susceptibility artifacts, water circulation has to be stopped for a certain period before an MR thermometry acquisition can be taken.…”

Systematic review about complementary medical hyperthermia in oncology

“…Conventional other medical procedures with heat such as HIPEC [ 35 ], HIVEC [ 36 ] or thermoablation [ 24 ] are not part of our review. Moreover, hyperthermia generated by high-frequency radiofrequency waves or with microwaves [ 37 ] with an adequate real-time thermal dose monitoring [ 38 , 39 ] meeting the requirements of the ESHO is also explicitly not part of our review [ 25 – 30 ].…”