This work quantitatively analyzed the reconstruction errors (REs) of electrical property (EP) images using a currently popular algorithm of magnetic resonance electrical property tomography (MREPT), which occurred along the tissue interfaces. Transmitted magnetic fields B1+ were acquired at 3 T using a birdcage coil loaded with a phantom consisting of various adjacent tissues. Homogeneous Helmholtz was employed to calculate the EP maps by Laplacian computation of central differences. The maps of absolute REs (aREs) and relative REs (rREs) were calculated. The maximum and mean rREs, in addition to rRE distributions at the interfaces, were presented. Reconstructed EP maps showed various REs along different interface boundaries. Among all the investigated tissue interfaces, the kidney-fat interface presented the maximum mean rREs for both conductivity and relative permittivity. The minimum mean rRE of conductivity was observed at the spleen-muscle interface, and the minimum mean rRE of relative permittivity was detected along the lung-heart interface. The mean rREs ranged from 0.3986 to 36.11 for conductivity and 0.2218 to 11.96 for relative permittivity. Overall, this research indicates that different REs occur at various tissue boundaries, as shown by the currently popular algorithm of MREPT. Thus, REs should be considered when applying MREPT to reconstruct the EP distributions inside the human body. Copyright © 2016 John Wiley & Sons, Ltd.

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The study was designed to identify differences in the dielectric properties of ex vivo colorectal cancerous tissues at different tumor stages. To date, 130 freshly excised colorectal cancerous specimens underwent measurement of both relative permittivity and conductivity on the serosal and mucosal surfaces of the carcinoma nidus, and the mucosa of the surgical resection margin ranging from 50 to 500 MHz at the Larmor frequencies. Tumor node metastasis staging was determined according to pathological reports for each patient. There were statistically significant differences in the relative permittivity of both colorectal cancerous serosa and mucosa among stages ≤I, II, III, and IV and between stages ≤II and ≥III (P < 0.05) at most frequencies under 300 MHz; statistically significant differences in conductivity were also observed for most of the measured frequencies (P < 0.05). The significant differences in dielectric characteristics among tumor stages, especially between early and advanced stages, have value for selecting appropriate surgical strategies. The presented ex vivo data provide important information for magnetic resonance electrical properties tomography in vivo system because the frequencies of 64 MHz (1.5T) and 128 MHz (3T) are usually used in clinical settings. Bioelectromagnetics. 38:522-532, 2017. © 2017 Wiley Periodicals, Inc.

Purpose To investigate the fixed‐jaw intensity‐modulated radiotherapy (F‐IMRT) and tangential partial volumetric modulated arc therapy (tP‐VMAT) treatment plans for synchronous bilateral breast cancer (SBBC). Materials and method Twelve SBBC patients with pTis‐2N0M0 stages who underwent whole‐breast irradiation after breast‐conserving surgery were planned with F‐IMRT and tP‐VMAT techniques prescribing 42.56 Gy (2.66 Gy*16f) to the breast. The F‐IMRT used 8‐12 jaw‐fixed tangential fields with single (sF‐IMRT) or two (F‐IMRT) isocenters located under the sternum or in the center of the left and right planning target volumes (PTVs), and tP‐VMAT used 4 tangential partial arcs with two isocenters located in the center of the left and right PTVs. Plan evaluation was based on dose‐volume histogram (DVH) analysis. Dosimetric parameters were calculated to evaluate plan quality; total monitor units (MUs), and the gamma analysis for patient‐specific quality assurance (QA) were also evaluated. Results For PTVs, the three plans had similar Dmean and conformity index (CI) values. F‐IMRT showed a slightly better target coverage according to the V100% values and demonstrated an obvious reduction in V105% and Dmax compared with the values observed for sF‐IMRT and tP‐VMAT. Compared with tP‐VMAT, sF‐IMRT was slightly better in terms of V100%, V105% and Dmax. In addition, F‐IMRT achieved the best homogeneity index (HI) values for PTVs. Concerning healthy tissue, tP‐VMAT had an advantage in minimizing the high dose volume. The MUs of the tP‐VMAT plan were decreased approximately 1.45 and 1 times compared with the sF‐IMRT and F‐IMRT plans, respectively, and all plans passed QA. For the lungs, heart and liver, F‐IMRT achieved the smallest values in terms of Dmean and showed a significant difference compared with tP‐VMAT. Simultaneously, sF‐IMRT was also superior to tP‐VMAT. For the coronary artery, tP‐VMAT achieved the lowest Dmean, while the value for F‐IMRT was 2.24% lower compared with sF‐IMRT. For all organs at risk (OARs), tP‐VMAT was superior at the high dose level. In contrast, sF‐IMRT and F‐IMRT were obviously superior at the low dose level. The sF‐IMRT and F‐IMRT plans showed consistent trends. Conclusion All treatment plans for the provided techniques were of high quality and feasible for SBBC patients. However, we recommend F‐IMRT with a single isocenter as a priority technique because of the tremendous advantage of local hot spot control in PTVs and the reduced dose to OARs at low dose levels. When the irradiated dose to the lungs and heart exceed the clinical restriction, two isocenter F‐IMRT can be used to maximize OAR sparing. Additionally, tP‐VMAT can be adopted for improving cold spots in PTVs or high‐dose exposure to normal tissue when the interval between PTVs is narrow.

Background Lung adenocarcinoma (LAD) is a highly aggressive malignant tumor which threatens the health and life of the population. Long non‐coding RNA X‐inactive specific transcript (XIST) and mouse double minute clone 2 (MDM2) are connected with the tumorigenesis of LAD. Nevertheless, whether MDM2 is regulated by XIST has not previously been reported in LAD. Methods Quantitative real‐time polymerase chain reaction (qRT‐PCR) was employed to detect the expression of XIST, microRNA‐363‐3p (miR‐363‐3p) and MDM2 in LAD tissues and cells. The proliferation, migration, invasion and apoptosis of LAD cells were determined by 3‐(4, 5‐dimethylthiazol‐2‐YI)‐2, 5‐diphenyltetrazolium bromide (MTT), transwell or flow cytometry assay, respectively. MDM2 protein level was detected using western blot analysis. Dual‐luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pulldown assay were performed to determine the interaction among XIST, miR‐363‐3p and MDM2. A xenograft tumor model was constructed to validate the effect of XIST on LAD cells in vivo. Results We found that XIST and MDM2 were remarkably elevated while miR‐363‐3p was reduced in LAD tissues and cells. Both XIST and MDM2 downregulation restrained proliferation, migration and invasion, and facilitated apoptosis of LAD cells in vitro. Importantly, XIST bound to miR‐363‐3p to modulate MDM2 expression in LAD cells. Moreover, miR‐363‐3p knockdown or MDM2 elevation reversed the effects of XIST downregulation on the proliferation, migration, invasion and apoptosis of LAD cells. Furthermore, XIST knockdown constrained tumor growth on LAD cells in vivo. Conclusions XIST knockdown repressed proliferation, migration and invasion, and accelerated apoptosis of LAD cells by downregulating MDM2 expression via binding to miR‐363‐3p. Key points Significant findings of the study XIST and MDM2 were abnormally enhanced in LAD tissues and cells. Both downregulation of XIST and MDM2 repressed proliferation, migration and invasion, and boosted apoptosis of LAD cells in vitro. XIST bound to miR‐363‐3p to regulate MDM2 expression in LAD cells. Downregulation of XIST impeded tumor growth on LAD cells in vivo.What this study addsThis study confirmed that XIST was a potential target for inhibiting the development of LAD, and affords a possible strategy for the treatment of LAD in the future.