[An exchange between the Japanese Society of Radiological Technology and the Chinese Society of Radiological Technology].
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China↗
Biomedical subjects
Shigeru Sanada
Publications and source records attributed to Shigeru Sanada.
[Morphological analysis for kinetic X-ray images of the temporomandibular joint].
The purpose of this study was to develop a screening technique for temporomandibular disorders (TMD) and assist dentists in objectively observing and evaluating pre/post-treatment status. Dynamic images of the temporomandibular joint (TMJ) from one healthy volunteer were obtained by digital fluoroscopy in the lateral view on both right and left sides. Outlines of the glenoid fossa and the condyle were extracted, respectively, by using sobel operator (7x7) thresholding and labeling. Morphological parameters in time-sequence, such as fossa ratio, area, and distance of the joint space, were then analyzed. There were no differences between manual and computer analysis in extracting the outline of the glenoid fossa and the condyle. Deformity of the outline of the glenoid fossa and the condyle was not identified in this subject. The fossa ratio was 0.30+/-0.01 on the right and 0.29+/-0.02 on the left. The area and distance of the joint space in the post-glenoid fossa were slightly larger than those in the articular eminence on both sides. These morphological parameters were useful for screening and pre- and post-treatment evaluation of TMD patients.
Adult↗
[Development of breathing chest radiography: study of exposure timing].
The flat-panel detector (FPD) has been introduced into clinical practice. A modified FPD, which has the ability to obtain dynamic chest radiographs, was introduced into our hospital, and clinical testing is ongoing. Both the inspiratory and expiratory phases have to be included in dynamic chest radiographs. The purpose of this study was to investigate the most appropriate chest radiography signal for observation of the respiratory process. We prepared ten protocol patterns that differed in terms of respiratory phase at X-ray exposure, exposure duration, and signal multiplicity. We also performed preliminary experiments and administered several questionnaires to ten volunteers. The volunteers breathed according to vocal and visual signals, and their respiratory waves were recorded by spirometer. The most appropriate protocol was similar to the method used for conventional chest radiography.
Adult↗
[Development of automated segmentation method for the posterior portion of the temporal lobe on coronal MR images].
Brain MRI is an important method for examining the diseases caused by various cerebral pathologies, and the measurement of temporal lobe volume is useful for identifying dementia and temporal lobe abnormalities. However, no segmentation algorithm for the temporal lobe on coronal MR images has been established. Such an algorithm is needed because the shape of the temporal lobe on coronal images varies from area to area. The purpose of this research was to develop a segmentation method for the posterior portion of the temporal lobe on coronal MR images. The subjects were 11 normal patients, whose coronal T(1)-weighted images were selected for this study. The preprocessing algorithm for segmentation consists of smoothing, binarization, and thinning. The first step of the segmentation process consists of recognition techniques for the temporal lobe region on thinning images. The next step is distance transformation on identified thinning images. Finally, the temporal lobe was segmented by using the original images and distance transformation images and employing the newly developed algorithm. The rate of accuracy of automated recognition was over 74% for all cases, while the average rate of accuracy was 83.2+/-4.0%. These results suggest that this segmentation method can clearly segment the temporal lobe and has potential for clinical use. Based on this study, although it included only 11 normal patients, we have started applying this segmentation method to many patients, with or without temporal lobe disease.
Adult↗
[Screening chest X-ray examination with kinetic analysis using flat-panel detector].
We are developing dynamic screening radiography to provide kinetic information for lung respiratory examination using a flat-panel-detector (FPD) system. We modified the FPD system (CANON CXDI-22) to take sequential images for a short period of time (10 seconds, 3 frames/sec). Sequential chest radiographs from full inspiration to expiration were taken and analyzed for diaphragm movement and density changes in local lung areas to objectively detect respiratory anomalies. Our methods derived some respiratory functions such as regional air passage and lung structure movement, and suggested that the degree of chronic obstructive pulmonary disease and interstitial pneumonia could be evaluated quantitatively.
Aged↗
Frequency analyses of CSF flow on cine MRI in normal pressure hydrocephalus.
Our objective was to clarify intracranial cerebrospinal fluid (CSF) flow dynamics in normal-pressure hydrocephalus (NPH). Frequency analyses of CSF flow measured with phase-contrast cine MRI were performed. The CSF flow spectra in the aqueduct were determined in patients ( n=51) with NPH, brain atrophy or asymptomatic ventricular dilation (VD), and in healthy volunteers (control group; n=25). The changes in CSF flow spectra were also analyzed after intravenous injection of acetazolamide. Moreover, a phase transfer function (PTF) calculated from the spectra of the driving vascular pulsation and CSF flow in the aqueduct were assessed. These values were compared with the pressure volume response (PVR). The amplitude in the NPH group was significantly larger than that in the VD or control group because of a decrease in compliance. The phase in the NPH group was significantly different from that in either the VD or the control group, but no difference was found between the VD and control groups. The amplitude increased in all groups after acetazolamide injection. The PTF in the NPH group was significantly larger than in the control group, and a positive correlation was noted between PTF and PVR. Frequency analyses of CSF flow measured by cine MRI make it possible to noninvasively obtain a more detailed picture of the pathophysiology of NPH.
Acetazolamide↗
Measurements of MTF and SNR(f) using a subtraction method in MRI.
A method was developed for accurate measurement of the modulation transfer function (MTF) and signal-to-noise ratio in the spatial frequency domain (SNR(f)) of magnetic resonance images (MRI). The MTF was calculated from the complex images of a line object which were obtained by the subtraction of two separately acquired data sets of a specially designed phantom with a sliding sheet. Moreover, the SNR(f) was calculated from the MTF and Wiener spectrum, both of which were determined using the same phantom configuration. The MTFs and SNR(f)s in the conventional spin-echo (SE) and turbo SE, in which the effective echo time was set to the first echo, were evaluated by changing the T2 of the phantom and the echo train length. The MTFs in the positive and negative frequencies indicated the effect of the k-space trajectory for each pulse sequence. SNR(f)s gave spatial frequency information that was not obtained with conventional methods. In this method, the influence of image nonuniformity and unwanted artefacts (edge and ghost) could be eliminated. An analysis of the MTF and the SNR in the spatial frequency domain provides additional information for the assessment of image quality in MRI.
Artifacts↗
Development of perfusion CT software for personal computers.
RATIONALE AND OBJECTIVES: The authors developed software for creating quantitative maps of arterial and portal perfusion in the upper abdominal organs on personal computers. The image quality of these perfusion computed tomographic (CT) images was visually evaluated. MATERIALS AND METHODS: In 58 patients (38 men, 20 women; mean age, 63.9 years +/- 11.9; range, 22-85 years) with various diseases of the upper abdomen, 91 single-section dynamic CT studies were obtained. The data were transferred on-line to a personal computer, and quantitative maps of arterial and portal perfusion were created by means of the maximum-slope method. Perfusion CT images were reviewed by a radiologist and a radiation technologist, and image quality was rated according to a four-category scoring system (1 = good quality, 2 = moderate, 3 = poor, 4 = images could not be created). RESULTS: Arterial perfusion CT images could be created in 81 (89%) of 91 examinations, and 74 images (81%) were scored as 1 or 2. Portal perfusion CT images could be created in 60 (68%) of 88 examinations, in which a portal trunk was included in the section, and 33 of them (38%) were scored as 1 or 2. Patient motion during dynamic CT sequences resulted in poor image quality in seven arterial and 27 portal perfusion images. CONCLUSION: Perfusion CT can combine quantitative perfusion maps with good anatomic detail in one image, although patient movement frequently degrades image quality in portal perfusion CT.
Abdomen↗
[New screening chest radiography with computer analysis of pulmonary marking movement and change in regional density].
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.
Humans↗
[New method of screening chest radiography with computer analysis of respiratory kinetics].
To develop a new method of screening chest radiography that would provide respiratory kinetics easily and automatically using flat-panel-detector capacitated fluoroscopy, we carried out a motion analysis of the diaphragm at several respiratory phases. We obtained five chest radiographs of healthy volunteer at five respiratory phases, from maximum inspiration to normal expiration. The edges of the diaphragm were enhanced by the first derivative filter, which select edge graduents within a limited range of orientations, and were detected by thresholding and analysis of connectivity in the horizontal direction. We measured the distance from the apex to the diaphragm as well as the changes at each phase. The apex was determined previously at the step of lung-region recognition. At the costophrenic angle, the change in the distance from the apex to the diaphragm was 2.44 cm on the right and 3.06 cm on the left, while at the paramedian region the changes were 0.74 cm on the right and 1.36 cm on the left. This new method of chest examination with computer analysis can provide information on diaphragm kinetics during respiration. In addition, it may aid in the early diagnosis of diseases such as chronic pulmonary emphysema and phrenic nerve paralysis.
Diaphragm↗
Perfusion changes of hepatic parenchyma due to infectious hepatobiliary disease: demonstration by perfusion CT.
We present two cases, in which perfusion CT demonstrated diffusely increased arterial and decreased portal perfusion of the liver parenchyma around liver abscess and infectious bilomas. These cases suggested that perfusion CT may be useful for a quantitative analysis of perfusion changes in infectious hepatobiliary diseases with good anatomical detail.
Aged↗