In vivo electrical properties of the healthy liver and the hepatic tumor in a mouse model between 1 Hz and 1 MHz during a thermal treatment.

Objective: Understansding the changing patterns of in vivo electrical properties for the target tissue is crucial for the accurate temperature monitoring and the treatment efficacy in thermal therapy. Our research aims to investigate the changing patterns and the reversibility of in vivo electrical properties for both healthy livers and liver tumors in a mouse model over a frequency range of 1 Hz to 1 MHz at temperatures between 30 °C to 90 °C.Methods and materials: The mice were anesthetized and the target organ was exposed. An 808-nm near-infrared laser was employed as the heating source to heat the organ in vivo. The four-needle electrode, connected to an impedance analyzer, was utilized to obtain the impedance at varying temperatures, which were monitored by a thermocouple.Results: The findings indicated a gradual decline in impedance with an increase in temperature. Furthermore, the impedance was normalized to that at 30 °C, and the real part of the normalized impedance was defined as the k-values, which range from 0 to 1. The results demonstrated a linear correlation between k-values and temperatures (R2 > 0.9 for livers and R2 > 0.8 for tumors). Significant differences were observed between livers and tumors at 1, 10 and 50 kHz (p < 0.05). Additionally, it was demonstrated that the electrical properties could be reversed when the temperature was below or equal to 45 °C.Conclusion: We believe that these results will contribute to the advancement of radiofrequency ablation systems and the development of techniques for temperature monitoring during liver thermal treatment.

Percutaneous Transluminal Angioplasty Alleviate Pediatric Postthrombotic Syndrome: A Case Report and Literature Review.

PURPOSE: Postthrombotic syndrome (PTS) is one of the long-term sequelae of deep vein thrombosis (DVT), and effective symptom management in pediatric PTS remains a challenge, with interventional therapy rarely explored in this population. We present a successful case of interventional treatment pediatric PTS, resulting in a remarkable amelioration of her symptoms. CASE REPORT: This case features a 6-year-old girl diagnosed with hyperinsulinemia, leading to a hypoglycemic coma. Following a mini-pancreatic partial pancreatectomy, she required further intensive care in the pediatric intensive care unit. It was during this period that left lower extremity DVT was identified, prompting warfarin anticoagulation therapy. During the anticoagulation period, she had several bleeding events and was switched to anticoagulation with low molecular heparin. One month later, the left common iliac vein and external iliac vein was found to be completely occluded. Over time, she experienced a gradual onset of lower limb swelling and pain, which, after 6 months, was accompanied by perineal edema and venous claudication. As a result, she underwent successful percutaneous transluminal angioplasty. In addition, the anticoagulation regimen was adjusted to rivaroxaban. At the 8-month follow-up, we observed significantly improvement in her postoperative lower extremity swelling and symptoms related to venous occlusion had completely disappeared. Moreover, vascular imaging confirmed improvement in stenosis and uninterrupted blood flow. CONCLUSIONS: In our review of pediatric PTS studies, we observed limited options to alleviate symptoms, and interventional treatments have not been reported. Our case study, demonstrating the safe and effective use of percutaneous transluminal angioplasty, helps to illuminate this area and alleviate pediatric PTS symptoms. CLINICAL IMPACT: This case validates the efficacy and safety of using percutaneous transluminal angioplasty (PTA) for the treatment of postthrombotic syndrome (PTS) in pediatric patients. This interventional approach offers significant symptomatic relief and improves quality of life, especially in cases where traditional anticoagulation therapies fail or lead to complications. The successful case presented emphasizes the necessity of considering endovascular interventions for children with moderate to severe PTS, particularly when conservative management is ineffective. This research underscores the potential for PTA to be adopted in clinical practice, offering a promising new approach for managing pediatric PTS.

A preliminary study on the application of electrical impedance tomography based on cerebral perfusion monitoring to intracranial pressure changes.

Background: In intracranial pathologic conditions of intracranial pressure (ICP) disturbance or hemodynamic instability, maintaining appropriate ICP may reduce the risk of ischemic brain injury. The change of ICP is often accompanied by the change of intracranial blood status. As a non-invasive functional imaging technique, the sensitivity of electrical impedance tomography (EIT) to cerebral hemodynamic changes has been preliminarily confirmed. However, no team has conducted a feasibility study on the dynamic detection of ICP by EIT technology from the perspective of non-invasive whole-brain blood perfusion monitoring. In this study, human brain EIT image sequence was obtained by in vivo measurement, from which a variety of indicators that can reflect the tidal changes of the whole brain impedance were extracted, in order to establish a new method for non-invasive monitoring of ICP changes from the level of cerebral blood perfusion monitoring. Methods: Valsalva maneuver (VM) was used to temporarily change the cerebral blood perfusion status of volunteers. The electrical impedance information of the brain during this process was continuously monitored by EIT device and real-time imaging was performed, and the hemodynamic indexes of bilateral middle cerebral arteries were monitored by transcranial Doppler (TCD). The changes in monitoring information obtained by the two techniques were compared and observed. Results: The EIT imaging results indicated that the image sequence showed obvious tidal changes with the heart beating. Perfusion indicators of vascular pulsation obtained from EIT images decreased significantly during the stabilization phase of the intervention (PAC: 242.94 ± 100.83, p < 0.01); perfusion index which reflects vascular resistance increased significantly in the stable stage of intervention (PDT: 79.72 ± 18.23, p < 0.001). After the intervention, the parameters gradually returned to the baseline level before compression. The changes of EIT indexes in the whole process are consistent with the changes of middle cerebral artery velocity related indexes shown in TCD results. Conclusion: The EIT image combined with the blood perfusion index proposed in this paper can reflect the decrease of cerebral blood flow under the condition of increased ICP in real time and intuitively. With the advantages of high time resolution and high sensitivity, EIT provides a new idea for non-invasive bedside measurement of ICP.

Temperature dependence of dielectric properties of blood at 10 Hz-100 MHz.

The temperature dependence of the dielectric properties of blood is important for studying the biological effects of electromagnetic fields, electromagnetic protection, disease diagnosis, and treatment. However, owing to the limitations of measurement methods, there are still some uncertainties regarding the temperature characteristics of the dielectric properties of blood at low and medium frequencies. In this study, we designed a composite impedance measurement box with high heat transfer efficiency that allowed for a four/two-electrode measurement method. Four-electrode measurements were carried out at 10 Hz-1 MHz to overcome the influence of electrode polarization, and two-electrode measurements were carried out at 100 Hz-100 MHz to avoid the influence of distribution parameters, and the data was integrated to achieve dielectric measurements at 10 Hz-100 MHz. At the same time, the temperature of fresh blood from rabbits was controlled at 17-39°C in combination with a temperature-controlled water sink. The results showed that the temperature coefficient for the real part of the resistivity of blood remained constant from 10 Hz to 100 kHz (-2.42%/°C) and then gradually decreased to -0.26%/°C. The temperature coefficient of the imaginary part was positive and bimodal from 6.31 kHz to 100 MHz, with peaks of 5.22%/°C and 4.14%/°C at 126 kHz and 39.8 MHz, respectively. Finally, a third-order function model was developed to describe the dielectric spectra at these temperatures, in which the resistivity parameter in each dispersion zone decreased linearly with temperature and each characteristic frequency increased linearly with temperature. The model could estimate the dielectric properties at any frequency and temperature in this range, and the maximum error was less than 1.39%, thus laying the foundation for subsequent studies.