Hirohito Takeuchi

Case study to assess the safety of irreversible electroporation near the heart

IntroductionIrreversible electroporation (IRE) is a promising technique for the focal treatment of soft tissue tumors. Even though the local application of an excessive electric field is a potential cause of cardiac arrhythmias, initial clinical studies have shown that IRE is generally safe when cardiac gating is employed.Case descriptionIn this case report, we observed an episode of ventricular extrasystoles without hemodynamic changes during which time the synchronization device failed to operate properly, with pulses delivered not in the absolute refractory period but in the relative refractory period.Discussion and evaluationAt present, persons performing IRE must keep in mind that there is a small but real risk of synchronization failure even when a cardiac synchronization device is used.ConclusionIt is advisable to err on the side of caution when treating lesions near the heart.

Viscoelasticity Measurement in Rat Livers Using Shear-Wave US Elastography

To investigate the usefulness of shear-wave speed and dispersion slope measurements obtained, using an ultrasound elastography system in rat livers with various degrees of necroinflammation and fibrosis. A total of 25 male Sprague Dawley rats were randomly divided into 5 groups of 5 rats each: G0 (control), G1 (CCl4 injected twice a week for 1 wk), G2 (CCl4 injected four times a wk for 1 wk), G3 (CCl4 injected twice a wk for 6 wk) and G4 (CCl4 injected twice a wk for 10 wk). The shear-wave speed (m/s) and the dispersion slope ([m/s]/kHz) were measured. Histologic features (inflammation, necrosis and fibrosis) were used as reference standards. In multivariable analysis with histologic features as independent variables, the fibrosis grade was significantly related to shear-wave speed (p < 0.05) and the necrosis grade was significantly related to dispersion slope (p < 0.05). Dispersion slope is more useful than shear-wave speed for predicting the degree of necroinflammation.