Respiratory function data are useful for the evaluation of lung disease. To develop a new method of computer analysis for screening chest radiography that would provide respiratory kinetics automatically, we quantified and analyzed the movement of pulmonary markings and the changes in lung density during respiration. In this study, we obtained fluoroscopic chest images of a healthy volunteer during respiration using an image intensifier(I. I.) fluoroscopy system. We analyzed the vector of the movement of pulmonary markings and measured the regional mean density of sequential chest images during respiration. The movement of pulmonary markings in the upper lung field was less than that in the lower lung field. Variation in the phase density curve of the upper lung field was less than that of the lower lung field. Our results indicate that changes in density were regular and were synchronized with respiration. This computerized method may aid radiologists in the evaluation of lung diseases such as chronic obstructive pulmonary disease (COPD), where abnormal respiratory change in density occurs as a result of air trapping.
Fading of the imaging plate (IP) in computed radiography (CR) systems with photostimulable phosphors is known well. The relation between noise properties and the fading of the IP in a CR system was investigated. Uniform exposure for the IP with various times between exposure and readout for the same exposure was used for this study. The relative intensity of photstimulated emisson and the digital Wiener spectra were calculated. The relative intensity of photstimulated emisson decreased with increasing time, whereas Wiener spectral values showed no difference with increasing time. We concluded that noise properties were not affected by the fading of the IP in the CR system.
To examine the possibility of diagnosing Alzheimer-type dementia, we studied this condition using the run length matrix, on head MR images of 29 Alzheimer-type dementia patients (8 men, 21 women 78.7±6.7 years) and healthy elderly controls (10 men, 19 women 72.3±8.7 years). The results showed that differences in GLN (gray level nonuniformity) and RLN (run length nonuniformity) were statistically significant. Furthermore, discriminant analysis based on GLN and RLN showed a rate of sensitivity of 69.0%, specificity 86.2%, and correct classification 77.6%. Although this rate of correct classification is inferior to the planimetric and volumetric methods, run length matrix is only one method of texture analysis. The results of this study indicate the possibility of MR imaging-based diagnosis of Alzheimer-type dementia with texture analysis including a run length matrix.
Low-frequency noise caused by intestinal gas, bone, or high-contrast subjects on roentgenographs often makes them difficult to read. The plantodorsal projection of the calcaneus taken by the conventional method has low-frequency noise because of its own high contrast for the long axis. Even if a higher X-ray tube voltage is used to reduce the low-frequency noise, middle- or high-frequency signals such as those of bone trabeculae are also reduced. We investigated a new method that takes into consideration the subject contrast between the part of the posterior calcanean articulation and distal part on the calcaneus projection, the spectrum of bone trabeculae, and the scatter fraction. The technique we introduced has some merit compared with the conventional method in that it reduces image distortion, provides low contrast for the long axis, and sharpens trabeculae images and articulations.
During this project, we evaluated methods to scan MRCP images with overlapping slice positions during one breath-hold using the FRSSFSE sequence. The FRSSFSE sequence is a technique to arbitrarily change the residual transverse magnetization to longitudinal magnetization. With the SSFSE sequence, the imaging field where the slice position overlaps is subject to substantial influence from the saturation effect of the water component. Therefore, one breath-hold is required for each image. However, the FRSSFSE sequence enabled the deterioration in image quality due to the saturation effect to be minimized even during a short TR. This enabled images of overlapping slice positions to be scanned during one breath-hold. We used a setting of TR=5,000 ms at our hospital, and scanned several images with overlapping slice positions during one breath-hold. The TR=5,000 ms setting was determined from image quality and breath-hold time considerations. The use of the FRSSFSE sequence with MRCP enabled 3-4 images to be scanned at overlapping slice positions during one breath-hold. This method is effective in reducing examination time and the burden on the patient.
Whole-body gallium planar scintigrapliy is a mainstay for the detection of tumors and inflammatory lesions. Recently, gallium SPECT (single photon emission computed tomography) has become more common in the clinical setting. This diagnostic modality is widely employed in our hospital, and lesions are actually detected by SPECT in some cases. Although the contrast of SPECT images is better than that of planar images, spatial resolution is limited by the limited matrix size. Thus, the overall diagnostic utility of SPECT remains to be confirmed. The usefulness of SPECT for the detection of gallium-accumulated lesions was evaluated in a phantom. In this study, we showed that SPECT is able to detect more smaller and lower gallium accumulations than planar imaging. Thus, SPECT imaging is useful in gallium scintigraphy.