Vulnerabilities of radiomic features to respiratory motion on four‐dimensional computed tomography‐based average intensity projection images: A phantom study

[Purpose] To evaluate the influence of respiratory motion on the robustness of radiomic features on four-dimensional computed tomography (4DCT)-based average intensity projection (AIP) images by employing an anthropomorphic chest phantom. [Methods] Three spherical objects (φ30 mm), namely, acrylic (100 Hounsfield unit [HU], homogeneous), rubber (−140 HU, homogeneous), and cork (−630 HU, heterogeneous), were moved with motion amplitudes of 0, 1, 2.5, 4, 6, 8, and 10 mm in the phantom, and 4DCT scans were repeated at four different locations. Thereafter, the AIP images were generated considering the average of the 10 respiratory phases of the 4DCT images. Further, the targets were manually delineated on the AIP images in the lung window setting. A total of 851 radiomic features, including 107 unfiltered features and 744 wavelet filter-based features, were extracted from the region of interest for each material. The feature robustness among the different target motion amplitude (ε) was evaluated by normalizing the feature variability of the target motion relative to the variability of data from 573 patients with early-stage non-small cell lung cancer. The features with absolute ε values ≤0.5 were considered highly robust to target motions. [Results] The percentage of robust unfiltered and wavelet filter-based features with a motion amplitude of 1 mm was greater than 83.2% and 93.4%, respectively; however, the percentage decreased by more than 24.3% and 17.6%, respectively, for motion amplitudes greater than 2.5 mm. The movement of cork had a small effect on the feature robustness compared to that of acrylic and rubber, regardless of the target motion amplitudes. [Conclusions] Our phantom study demonstrated that target motion amplitudes ≤1 mm led to the robustness of radiomic features on the 4DCT-based AIP images of thoracic regions. The frequency components and directions of the wavelet filters may be essential factors in 4DCT-based radiomic analysis

Is the Comet Assay a Sensitive Procedure for Detecting Genotoxicity?

Although the Comet assay, a procedure for quantitating DNA damage in mammalian cells, is considered sensitive, it has never been ascertained that its sensitivity is higher than the sensitivity of other genotoxicity assays in mammalian cells. To determine whether the power of the Comet assay to detect a low level of genotoxic potential is superior to those of other genotoxicity assays in mammalian cells, we compared the results of Comet assay with those of micronucleus test (MN test). WTK1 human lymphoblastoid cells were exposed to methyl nitrosourea (MNU), ethyl nitrosourea (ENU), methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), bleomycin (BLM), or UVC. In Comet assay, cells were exposed to each mutagen with (Comet assay/araC) and without (Comet assay) DNA repair inhibitors (araC and hydroxyurea). Furthermore, acellular Comet assay (acellular assay) was performed to determine how single-strand breaks (SSBs) as the initial damage contributes to DNA migration and/or to micronucleus formation. The lowest genotoxic dose (LGD), which is defined as the lowest dose at which each mutagen causes a positive response on each genotoxicity assay, was used to compare the power of the Comet assay to detect a low level of genotoxic potential and that of MN test; that is, a low LGD indicates a high power. Results are summarized as follows: (1) for all mutagens studied, LGDs were MN test ≦ Comet assay; (2) except for BLM, LGDs were Comet assay/araC ≦ MN test; (3) except for UVC and MNU, LGDs were acellular assay ≦ Comet assay/araC ≦ MN test ≦ Comet assay. The following is suggested by the present findings: (1) LGD in the Comet assay is higher than that in MN test, which suggests that the power of the MN test to detect a low level of genotoxic potential is superior to that of the Comet assay; (2) for the studied mutagens, all assays were able to detect all mutagens correctly, which suggests that the sensitivity of the Comet assay and that of the MN test were exactly identical; (3) the power of the Comet assay to detect a low level of genotoxic potential can be elevated to a level higher than that of MN test by using DNA resynthesis inhibitors, such as araC and HU

Relation Between Severity of Magnesium Deficiency and Frequency of Anginal Attacks in Men With Variant Angina

AbstractObjectives. We evaluated whether the severity of magnesium deficiency was correlated with the frequency of attacks of variant angina.Background. Magnesium deficiency may be associated with the development of variant angina. However, the relation between the activity of variant angina and magnesium deficiency remains to be elucidated.Methods. We assessed the body magnesium status of 18 men with variant angina: Group 1 (≥4 attacks/week, n = 7) and Group 2 (<4 attacks/week, n = 11). Concentrations of magnesium were determined in serum, urine, mononuclear cells and erythrocytes, and the 24-h magnesium retention rate was determined.Results. Group 1 showed a higher 24-h magnesium retention rate (mean ± SEM 63.5 ± 7.6% vs. 24.9 ± 2.7%, p < 0.01) and a lower intracellular concentration of magnesium in mononuclear cells and erythrocytes than did Group 2 (respectively, 156.3 ± 13.5 vs. 212.1 ± 6.9 fg/cell, p < 0.01; and 3.5 ± 0.5 vs. 5.2 ± 0.4 fg/cell, p < 0.05), demonstrating the presence of magnesium deficiency in Group 1. The 24-h magnesium retention rate and intracellular concentrations of magnesium in mononuclear cells and erythrocytes correlated well with the frequency of anginal attacks (r = 0.78, p < 0.01; r = −0.78, p < 0.01; r = −0.62, p < 0.01, respectively) for all patients.Conclusions. Data suggest that the magnesium status of men with variant angina is closely related to disease activity

Trochanteric Claw Plate Fixation for Greater Trochanteric Fracture or Osteotomy in Total Hip Arthroplasty

This study retrospectively evaluated 41 consecutive open reductions and internal fixations following primary or revision total hip arthroplasty, which required trochanteric claw plate fixation for greater trochanteric fracture or osteotomy between January 2008 and December 2020. The mean duration of clinical follow-up was 4.2 years (range, 1-13 years). The patients included 13 men and 28 women, with a mean age of 68 years (range, 32-87 years). The indications for intervention included trochanteric osteotomy, intraoperative fracture, and non-union including postoperative fracture in 6, 9, and 26 cases, respectively. The mean Merle d’Aubigné Clinical Score improved from 9.4 points (range, 5-15 points) pre-operatively, to 14.3 points (range, 9-18 points) at the last follow-up. Bone union occurred in 35 cases (85%), while implant breakage occurred in four cases. At the last follow-up, the mean Merle d’Aubigné Clinical Scores of bone union and non-union were 15.3 and 14.1, respectively (p=0.48). The Kaplan-Meier survival rate, with the endpoint being revision surgery for pain, non-union, dislocation, or implant breakage, at 10 years was 80.0% (95% confidence interval: 62.6-97.4%). Greater trochanteric fixation using a trochanteric claw plate yielded successful results

Maintenance of centrosome integrity under stress conditions by a PLK4, p53 and SAPK pathway network

学位の種別:課程博士University of Tokyo(東京大学