Validation of a Web-Based Planning Tool for Percutaneous Cryoablation of Renal Tumors

Abstract

Purpose To validate a simulation environment for virtual planning of percutaneous cryoablation of renal tumors. Materials and Methods Prospectively collected data from 19 MR-guided procedures were used for validation of the simulation model. Volumetric overlap of the simulated ablation zone volume (Σ) and the segmented ablation zone volume (S; assessed on 1-month follow-up scan) was quantified. Validation metrics were DICE Similarity Coefficient (DSC; the ratio between twice the overlapping volume of both ablation zones divided by the sum of both ablation zone volumes), target overlap (the ratio between the overlapping volume of both ablation zones to the volume of S; low ratio means S is underestimated), and positive predictive value (the ratio between the overlapping volume of both ablation zones to the volume of Σ; low ratio means S is overestimated). Values were between 0 (no alignment) and 1 (perfect alignment), a value > 0.7 is considered good. Results Mean volumes of S and Σ were 14.8 cm3 (± 9.9) and 26.7 cm3 (± 15.0), respectively. Mean DSC value was 0.63 (± 0.2), and ≥ 0.7 in 9 cases (47%). Mean target overlap and positive predictive value were 0.88 (± 0.11) and 0.53 (± 0.24), respectively. In 17 cases (89%), target overlap was ≥ 0.7; positive predictive value was ≥ 0.7 in 4 cases (21%) and < 0.6 in 13 cases (68%). This indicates S is overestimated in the majority of cases. Conclusion The validation results showed a tendency of the simulation model to overestimate the ablation effect. Model adjustments are necessary to make it suitable for clinical use.

Model-based hepatic percutaneous microwaveablation planning. First validation on a clinical dataset

“…Model-based thermal ablation planning is a promising approach to assist the radiologist with the procedure, providing essential information on treatment settings. This has been shown in several studies for cryoablation, radiofrequency (RF), microwave (MW) and laser ablation in (pre-)clinical scenarios [11][12][13][14][15][16][17][18] . In this study, a biophysical model of thermal ablation is integrated in a prototype software which processes magnetic resonance imaging (MRI), or computed tomography (CT) imaging acquired during the regular clinical workflow.…”

Intraoperative MRI-derived volumetric ablation margins and initial correlation with local outcome after MRI-guided cryoablation of renal tumors

“…Institutional Review Board approval for retrospective use of data was obtained for this single-center retrospective case study, and informed consent was waived. Data of several included patient data were previously reported in other studies [6,17] that had different study objectives and were not focused on determining peri-ablational treatment margins.…”

“…Needle positions were verified using T2-weighted HASTE imaging and repositioned under MRI-guidance before the first freezing cycle if inadequate placement was suspected. All 32 procedures were performed in a wide-bore 3-T MR scanner, as previously described [17]. Cryoablation was performed using a double-cycle protocol of 10 min freezing, 2 min passive thawing and 1 min active thawing.…”

Hybrid Simulation and Planning Platform for Cryosurgery with Microsoft HoloLens

“…The system could be used for different thermal treatments but has not yet been tested for cryoablation procedures. Finally, in [ 19 ], a web-based planning tool for percutaneous cryoablation of renal tumours, based on a modified Pennes bioheat equation with an added perfusion term, is presented. However, validation results showed a tendency of the simulation model to overestimate the ablation effect, thus adjustments are necessary to make the tool suitable for clinical use.…”