Design of Hemispherical Radio Frequency (RF) Capacitive-type Electrode Free of Edge Effects for Treatment of Intracavitary Tumors

A new hemispherical electrode to heat oral cavity cancer is proposed. The electrode does not produce a hot spot around its edge, a feature that usually arises when using radio frequency (RF) capacitive-type heating. The hemispherical electrode was designed by computer simulation using a 3-D finite element method. To assess its practicality and effectiveness, we built a prototype hemispherical electrode and evaluated its heating characteristics by phantom experiments. The heating effects on the phantom were measured by thermography. The concave phantom surface in contact with the hemispherical electrode showed a uniform increase in temperature, with no obvious edge effect. The proposed electrode allows non-invasive RF capacitive-type heating for intracavity tumors that was not previously considered possible, and should contribute to the multidisciplinary treatment of intracavity tumors

Coil volume embolization ratio for preventing recanalization after portal vein embolization

PURPOSEThe purpose of this study was to evaluate the optimum volume embolization ratio (VER) for the prevention of recanalization after portal vein embolization (PVE) and the influence of recanalization on future liver remnant (FLR) function using technetium-99m galactosyl human serum albumin single-photon emission computed tomography (99mTc-GSA SPECT/CT) fusion imaging.METHODSWe analyzed procedural data of 18 patients who underwent PVE from 2015 to 2018. A total of 29 portal branches were embolized (12 anterior branch, 11 posterior branch, 4 left branch, 2 right branch) with absolute ethanol and coils. Portal vein recanalization was evaluated three weeks after PVE by contrast-enhanced CT. We classified the treated portal branches as non-recanalized and recanalized. VER was compared between the groups. In addition, for each patient, we calculated and evaluated the ratio of FLR volume to total liver volume (volumetric %FLR), FLR count to total liver count on 99mTc-GSA SPECT/CT fusion imaging (functional %FLR), and functional-volumetric ratio (functional %FLR/ volumetric %FLR).RESULTSTwenty-six portal branches showed no recanalization (non-recanalized group, n=26, 89.7%), while three portal branches showed recanalization (recanalized group, n=3, 10.3%). The median VER was 4.94% (3.12%–11.1%) in the non-recanalized group and 3.49% (2.76%–4.32%) in the recanalized group, which was significantly different between the groups (p = 0.045, Mann-Whitney U test). The median functional-volumetric ratio was 1.16 (1.03–1.50) in non-recanalized patients (n=15, 83.3%) and 1.01 (0.96–1.13) in recanalized patients (n=3, 16.7%), and it was significantly higher in the non-recanalized patients (p = 0.021, Mann-Whitney U test).CONCLUSIONThe VER for preventing recanalization after PVE was approximately 5% (> 4.94%). 99mTc-GSA SPECT/CT fusion imaging revealed a decrease in FLR function due to recanalization after PVE

Liver regeneration after portal vein embolization: comparison between absolute ethanol and N-butyl-cyanoacrylate in an in vivo rat model

PURPOSETo compare the effects of absolute ethanol (ethanol) and N-butyl-cyanoacrylate (NBCA) on non-embolized liver lobe regeneration in a rat model.METHODSTwenty-seven Sprague–Dawley rats underwent portal vein embolization (PVE) using ethanol:lipiodol, 1:1 (ethanol group, n = 11, 40.74%), NBCA:lipiodol, 1:1 (NBCA group, n = 11, 40.74%), or sham treatment (sham group, n = 5, 18.52%). The non-embolized and embolized lobe-to-whole liver weight ratios 14 days after PVE were compared among the groups (n = 5, 18.52%). The expressions of CD68 and Ki-67 and embolized-lobe necrotic area percentages one day after PVE were compared between the ethanol (n = 3, 11.11%) and NBCA (n = 3, 11.11%) groups.RESULTSThe non-embolized lobe-to-whole liver weight ratio after PVE was significantly higher in the NBCA group (n = 5, 33.33%) than in the ethanol group (n = 5, 33.33%) (84.28% ± 1.53% vs. 76.88% ± 4.12%, P = 0.029). The embolized lobe-to-whole liver weight ratio after PVE was significantly lower in the NBCA group than in the ethanol group (15.72% ± 1.53% vs. 23.12% ± 4.12%, P = 0.029). The proportions of CD68- and Ki-67-positive cells in the non-embolized lobe after PVE were significantly higher in the NBCA group (n = 30, 50%) than in the ethanol group (n = 30, 50%) [60 (48–79) vs. 55 (37–70), P = 0.003; 1 (0–2) vs. 1 (0–2), P = 0.004]. The embolized-lobe necrotic area percentage after PVE was significantly larger in the NBCA group (n = 30, 50%) than in the ethanol group (n = 30, 50%) [29.46 (12.56–83.90%) vs. 16.34 (3.22–32.0%), P < 0.001].CONCLUSIONPVE with NBCA induced a larger necrotic area in the embolized lobe and promoted greater non-embolized liver lobe regeneration compared with PVE with ethanol

Evaluation of the difference-correction effect of the gamma camera systems used by easy Z-score Imaging System (eZIS) analysis

Objective: We examined the difference of the effect by data to revise a gamma camera difference. The difference-correction method of the camera is incorporated in eZIS analysis. Methods: We acquired single photon emission computed tomography (SPECT) data from the three-dimensional (3D) Hoffman brain phantom (Hoffman), the three-dimensional brain phantom (3D-Brain), Pool phantom (pool) and from normal subjects (Normal-SPECT) to investigate compensating for a difference in gamma camera systems. We compared SPECT counts of standard camera with the SPECT counts that revised the difference of the gamma camera system (camera). Furthermore, we compared the "Z-score map (Z-score)". To verify the effect of the compensation, we examined digitally simulated data designed to represent a patient with Alzheimer\u27s dementia. We carried out both eZIS analysis and "Specific Volume of interest Analysis (SVA)". Results: There was no great difference between the correction effect using Hoffman phantom data and that using 3D-Brain phantom data. Furthermore, a good compensation effect was obtained only over a limited area. The compensation based on the pool was found to be less satisfactory than any of the other compensations according to all results of the measurements examined in the study. The compensation based on the Normal-SPECT data resulted in a Z-score map (Z-score) for the result that approximated that from the standard camera. Therefore, we concluded that the effect of the compensation based on Normal-SPECT data was the best of the four methods tested. Conclusions: Based on eZIS analysis, the compensation using the pool data was inferior to the compensations using the other methods tested. Based on the results of the SAV analysis, the effect of the compensation using the Hoffman data was better than the effect of the compensation using the 3D-Brain data. By all end-point measures, the compensation based on the Normal-SPECT data was more accurate than the compensation based on any of the other three phantoms. © 2014 The Author(s).発行後1年より全文公

Novel method for quantitative evaluation of cardiac amyloidosis using 201TlCl and 99mTc-PYP SPECT

Objective The degree of myocardial technetium- 99m- pyrophosphate ( 99mTc-PYP) accumulation in cardiac amyloidosis is conventionally evaluated by the PYP score. This method involves qualitative visual evaluation on twodimensional images. Here, we performed three-dimensional quantitative analysis using software developed in our laboratory. Methods We performed dual myocardial imaging using thallium- 201-chloride ( 201Tl-Cl) and 99mTc-PYP in cases of suspected cardiac amyloidosis and calculated the PYP accumulation rates of all myocardial pixels showing 99mTc- PYP accumulation. We defined this procedure as quantitative evaluation of the degree of 99mTc-PYP accumulation in the myocardium. Patients were divided into two groups with and without a diagnosis of cardiac amyloidosis, and we examined the PYP accumulation rates in both groups. In addition, we examined the PYP scores of the two groups by conventional qualitative evaluation. Results The PYP scores of the cardiac amyloidosis group were significantly higher than those of the other group. The PYP accumulation rates of the cardiac amyloidosis group were significantly higher than those of the other group. There were significant differences in the PYP accumulation rate and PYP score between the two groups. There was considered to be a threshold between the two groups in the case of the PYP accumulation rate. Conclusions When the threshold of the PYP score was defined as 3+ and that of the PYP accumulation rate as 41.5 %, the sensitivity of the PYP score and PYP accumulation rate was 84.6 %. However, the specificity of the PYP accumulation rate was higher than that of the PYP score. Quantitative evaluation by the PYP accumulation rate of the degree of 99mTc-PYP accumulation in the myocardium may be useful in the diagnosis of cardiac amyloidosis. © The Japanese Society of Nuclear Medicine 2012