A novel software platform for volumetric assessment of ablation completeness

Purpose: To retrospectively evaluate the accuracy of a novel software platform for assessing completeness of percutaneous thermal ablations. Materials & methods: Ninety hepatocellular carcinomas (HCCs) in 50 patients receiving percutaneous ultrasound-guided microwave ablation (MWA) that resulted in apparent technical success at 24-h post-ablation computed tomography (CT) and with ≥1-year imaging follow-up were randomly selected from a 320 HCC ablation database (2010–2016). Using a novel volumetric registration software, pre-ablation CT volumes of the HCCs without and with the addition of a 5 mm safety margin, and corresponding post-ablation necrosis volumes were segmented, co-registered and overlapped. These were compared to visual side-by-side inspection of axial images. Results: At 1-year follow-up, CT showed absence of local tumor progression (LTP) in 69/90 (76.7%) cases and LTP in 21/90 (23.3%). For HCCs classified by the software as "incomplete tumor treatments", LTP developed in 13/17 (76.5%) and all 13 (100%) of these LTPs occurred exactly where residual non-ablated tumor was identified by retrospective software analysis. HCCs classified as "complete ablation with <100% 5 mm ablative margins" had LTP in 8/49 (16.3%), while none of 24 HCCs with "complete ablation including 100% 5 mm ablative margins" had LTP. Differences in LTP between both partially ablated HCCs vs completely ablated HCCs, and ablated HCCs with <100% vs with 100% 5 mm margins were statistically significant (p < .0001 and p = .036, respectively). Thus, 13/21 (61.9%) incomplete tumor treatments could have been detected immediately, were the software available at the time of ablation. Conclusions: A novel software platform for volumetric assessment of ablation completeness may increase the detection of incompletely ablated tumors, thereby holding the potential to avoid subsequent recurrences

Effect of nanostructure on the thermal conductivity of La-doped SrTiO3 ceramics

A series of La-doped (10 at.%) SrTiO 3 ceramics with grain size ranging from 6 m to 24 nm was prepared from nanocrystalline powders using high-pressure field assisted sintering (HP-FAST). A progressive reduction of thermal conductivity \u3ba with decreasing grain size was observed. At room temperature, \u3ba of the ceramic with grain size of 24 nm (1.2 W m 12 1 K 12 1 ) is one order of magnitude lower than that of undoped single crystals. The strong suppression of \u3ba can be ascribed to (i) the high concentration of lattice defects, (ii) the increasing contribution of grain boundaries to phonon scattering when the grain size is decreased to the nanoscale and (iii) a moderate amount (10\u201315 vol.%) of nanopores. These results demonstrate that nanostructuration can be a successful strategy to attain a considerable reduction of \u3ba in heavily doped bulk oxide ceramics. The low electrical conductivity of the La:SrTiO 3 nanoceramics represents a major obstacle for thermoelectric applications