[Evaluation of appropriate slice thickness setting in multidetector-row CT examinations for screening of liver cancer].

UNLABELLED: In this study, we evaluated clinical images to determine appropriate settings for slice thickness in screening examinations for hepatocellular carcinoma and metastatic liver cancer, which are frequently performed in abdominal CT. The clinical images of 15 cases screened for hepatocellular carcinoma and 15 cases screened for metastatic liver cancer were evaluated. The evaluation was visually performed by three abdominal radiologists, and the sensitivity and specificity of each slice thickness were calculated. RESULTS: differences in sensitivity and specificity were not found between slice thicknesses of 2.5 mm and 5.0 mm; however, sensitivity and specificity were low, and confidence was also low at a 10.0 mm slice thickness. Furthermore, when a 5.0 mm slice thickness was adopted, it was shown that radiation dose in limited parts could be reduced greatly to a noise level that compared equally with a study in which a 2.5 mm slice thickness was adopted in another evaluation. Therefore, the objective could be achieved by using a slice thickness of about 5.0 mm in multidetector-row CT examinations for the screening of liver cancer, while controlling patient dose to a minimum.

Externalization of annexin I from a folliculo-stellate-like cell line.

Our recent studies on rat pituitary tissue suggest that the annexin I-dependent inhibitory actions of glucocorticoids may not be exerted directly on endocrine cells but indirectly via folliculo-stellate (FS) cells. FS cells contain glucocorticoid receptors and abundant annexin I. We have studied the localization of annexin I in FS cells and the ability of dexamethasone to induce annexin I secretion by an FS (TtT/GF) cell line, using Western blotting and immunofluorescence microscopy. Exposure of TtT/GF cells to dexamethasone (0.1 micro M, 3 h) caused an increase in the amount of annexin I protein in the intracellular compartment and attached to the surface of the cells. In nonpermeabilized cells, immunofluorescence labeling revealed that annexin I immunoreactivity was associated with the cell surface and concentrated in focal patches on the ends of cytoplasmic processes; dexamethasone (0.1 micro M, 3 h) increased both the number and intensity of these foci. Immunogold electron microscopy confirmed in anterior pituitary tissue the presence of immunoreactive-annexin at the surface of FS cell processes contacting endocrine cells. These data support our hypothesis that annexin I is released by FS cells in response to glucocorticoids to mediate glucocorticoid inhibitory actions on pituitary hormone release via a juxtacrine mechanism.

Preliminary investigation of the clinical usefulness of super-high-resolution LCDs with 9 and 15 mega-sub-pixels: observation studies with phantoms.

Our purpose in this study was to evaluate the preliminary clinical efficacy of soft-copy reading of digital mammography, for a 15-mega-sub-pixel (MsP) and a 9-MsP super-high-resolution liquid-crystal display (SHR-LCD) by use of an independent sub-pixel driving technology. We performed three kinds of phantom observation studies by six radiological technologists. Detectability of a contrast-detail phantom and simulated small objects (SSOs) resembling microcalcifications (MCLs), and shape discrimination ability of SSOs with round and square shapes, were examined and compared with a 5-MP conventional LCD (5-MP LCD). In each study, four types of display magnification ratio were used. The detectability and the shape discrimination ability of the 15-MsP SHR-LCD were highest among the three LCDs of most of the display magnification ratios. The 9-MsP SHR-LCD indicated a higher or equal performance as compared with the 5-MP LCD in the SSO detection and shape studies. The results of our study demonstrated that the SHR-LCDs had good potential to detect MCLs and to evaluate the shape in high-resolution digital mammography.

Analysis method of noise power spectrum for medical monochrome liquid crystal displays.

We investigated methods of analyzing the noise power spectrum (NPS) measurement for medical liquid crystal displays (LCDs). Uniform images displayed on the LCDs were imaged with a high-performance digital camera equipped with a close-up lens, and then the NPSs were calculated from the image data by means of several analysis methods. In a method using the 2D fast Fourier transform (FFT) with a 256 x 256 pixels data segment (basic method), we examined the efficacy of a background trend correction (BTC) and a Hanning windowing process used for reducing the spectral estimation errors in the Fourier analysis. To improve the frequency resolution of the basic method, we examined two 2D FFT methods by using 512 x 512 and 1024 x 1024 pixel segments. In addition, we studied a 1D FFT method with 1024-point 1D noise profiles (1D method). In these three methods, the BTC by a second-order polynomial fit and Hanning windowing were commonly applied. A 3-mega-pixel (MP) and a 5-MP monochrome LCD were employed for evaluating the respective methods. Also, a prototype 5-MP LCD equipped with a new anti-reflection surface-coated panel was compared with the conventional 5-MP LCD. The Hanning windowing process was indispensable for avoiding the spectral leakage errors caused by the pixel structures of the LCD. Sufficient frequency resolution was obtained by the 2D FFT method with the 1024 x 1024 pixels segments and the 1D method. The method which provided the most reliable NPSs was the 1D method, with which the BTC was achieved successfully.