[Basic MRI Study in the Imaging Direction of a Diffusion-weighted Whole Body with Background Body Signal Suppression].

A diffusion-weighted whole body with background body signal suppression (DWIBS) is usually imaged as a whole body with Transverse (Tra). However, Tra has a large number of stations and a larger number than Coronal (Cor), so the scan time is longer. There are also drawbacks, such as signal unevenness between series. It is known that the effect of distortion is large in Cor. There is no report on it in Sagittal (Sag). Therefore, in this study, we focused on Sag and examined the imaging time, image distortion, fat suppression effect, and continuity between stations. In the examination by the phantom, the scan time was the shortest for Cor and the longest for Sag. In the strain evaluation, the effect of strain could be suppressed compared to Cor by using a rectangle field of view (FOV) in the anterior to posterior (AP) direction in Tra and Sag. There was no difference in the fat suppression effect depending on the imaging direction. Similar results were obtained in a study of 10 healthy volunteers, with Sag having the best continuity between stations.

Evaluation of the Performance of Different Types of Radiation Protection Gloves: A Cross-sectional Study.

ABSTRACT: Radiation exposure of a practitioner's fingers is a problem in interventional radiology, and radiation protection gloves (protective gloves) can help reduce such exposure. Several types of protective gloves are commercially available from various manufacturers. In the present study, we compared the protective effects and usability of four types of protective gloves. To investigate the radiation protection effect, we placed normal surgical gloves and the four types of protective gloves on phantom hands with thermoluminescent dosimeters (TLD) attached to the fingertips and the dorsum and palms of the hands. Next, they were irradiated with x rays, and the radiation dose was measured and compared using the TLDs. In terms of usability, 42 medical staff members completed a questionnaire that included seven items, such as finger movability, tactile sensation, grip, and overall satisfaction, which were scored on a 5-point scale. Consequently, the protective effects differed between the gloves, and radiation exposure was lower by 30% to 60% with these gloves compared with surgical gloves. In terms of usability, a difference of 2 to 4 points was noted between the gloves for each questionnaire item. These results suggest that radiation protective gloves can protect the surgeon's fingers from radiation exposure without reducing work efficiency by selecting gloves according to the surgical procedure.

[Relationship between Left Ventricle Myocardium Volume in Coronary Territories' Analysis and Fractional Flow Reserve].

This study aimed to investigate the feasibility of estimating functional ischemia information from coronary artery computed tomography (CACT) data (i.e., morphological information). Fifty-five suspected ischemic heart disease patients were included in this study. To calculate the ischemic myocardium percentage (LV myocardial territories volume of distal portion the stenotic lesion/total LV myocardial volume) from CACT data with "coronary territories analysis, Ziostation2", and compared with the ischemic LV myocardium percentage and the functional flow reserve (FFR). The results showed that ischemic LV myocardium percentage was correlated with the FFR (r=-0.57). The median ischemic LV myocardium percentage of the FFR-positive group (n=33) was 37.1% (interquartile range [IQR] 33, 41.4%) and that of the FFR-negative group (n=22) was 24.8% (IQR 19.6, 30.6%). The ischemic LV myocardium percentage was significantly higher in the FFR-positive group (p<0.01) than in the FFR-negative group. The receiver operating characteristic (ROC) curve showed that the cutoff value for the ischemic LV myocardium percentage was 30%, with the sensitivity of 90.9% and the specificity of 77.3%. In conclusion, myocardial ischemia to diagnosis of FFR may occur when ischemic LV myocardium percentage is over than 30% and is unlikely to occur when it is less than 30%. This study suggests that the analysis of CACT data may contribute to the diagnosis of functional ischemia.

[The Effect of Radiation Protection Education for the Operators' Ocular Lens in Cardiac Catheterization].

The purpose of this study was to educate operators regarding cardiac catheterization using radiation protection slides prepared for this study and to consider whether or not this radiation protection education contributes to reducing the exposure of the operator's ocular lens. Thermoluminescent dosimeter (TLD) was installed at the outside left, inside left, outside right, and inside right of the X-ray protective eyewear of the operators performing the cardiac catheterization. The exposure dose rate before and after radiation protection education for 3 operators performing cardiac catheterization was compared. The exposure dose ratio was defined by dividing the TLD measurement value, which is the air kerma calculated by the X-ray diagnosis apparatus for the angiography. In other words, this can calculate the ratio of how much the operators are exposed to radiation from the dose of the patient per examination. When comparing the radiation dose ratio obtained from the dosimeter installed on the right outer side before and after education, p-value was <0.05 in the left anterior oblique-cranial and right anterior oblique- cranial, and a significant difference was recognized. The radiation protection education carried out in this study contributes to a reduction in the exposure dose of the operators.

Validation of a Metal Artifact Reduction Algorithm Using 1D Linear Interpolation for Cone Beam CT after Endovascular Coiling Therapy for Cerebral Aneurysms.

This study aimed to evaluate the effect of a metal artifact reduction (MAR) algorithm using 1D linear interpolation on cone-beam CT (CBCT). We performed phantom and clinical qualitative studies with and without MAR application using 1D linear interpolation. In the phantom study, the standard deviation (SD) was estimated from the images obtained from the water phantom in which a metal coil was placed at the center, and observed the changes in the SDs before and after MAR application. In the clinical qualitative study, the clinical images after endovascular treatment (EVT) for cerebral aneurysms were visually evaluated before and after MAR application. In the phantom study, the SDs after MAR application decreased by 56 to 35% compared with that before MAR application. In the clinical qualitative study, the artifacts from the metal coil decreased or increased depending on locations, and the contrasts of gray matter and white matter were attenuated when MAR was applied. In conclusion, the metal artifact decreases when MAR using 1D linear interpolation is applied to cerebral CBCT. However, another artifacts increase or soft tissue contrast is changed in some cases. MAR largely contributes to the reduction of streaking artifacts, whereas it may induce cerebral parenchyma at distant metal body or quality deterioration of the image not including the metal body. This should be taken into account in the diagnosis of secondary hemorrhage or infarction.

[Effect of Kiken-Yochi training (KYT) induction on patient safety at the department of radiological technology].

PURPOSE: In this report, we evaluated whether radiological technologists' (RTs') awareness of patient safety would improve and what kind of effects would be seen at the department of radiological technology by introducing KYT [K: kiken (hazard), Y: yochi (prediction), T: (training)]. METHODS: KYT was carried out by ten RTs based on a KYT sheet for the department of radiological technology. To evaluate the effects of KYT, we asked nine questions each to ten participants before and after KYT enforcement with regard to their attitude to patient safety and to operating procedures for working safely. RESULTS: Significant improvements after KYT enforcement were obtained in two items concerning medical safety: It is important for any risk to be considered by more than one person; The interest in preventive measures against medical accident degree conducted now) and one concerning operating procedures (It is necessary to have a nurse assist during testing with the mobile X-ray apparatus) (p<0.05). CONCLUSIONS: Performing KYT resulted in improved awareness of the importance of patient safety. KYT also enabled medical staffers to evaluate objectively whether the medical safety measures currently performed would be effective for patients.

[Observations of deterioration of photo-stimulable phosphor plates used in digital mammography and its effects on mammography diagnoses].

We noted that breast-like artifacts occur in photo-stimulable phosphor plates (PSPs) used for long periods in digital mammography systems. This prompted us to investigate the effects on mammography diagnoses of these artifacts. Our study took the form of a comparison between the images generated by a long-term use PSP (four years use) and a short-term use PSP. First, an acrylic phantom and an in-house-made phantom for visual evaluation were imaged using X-ray PSPs under the same exposure conditions. They were then scanned under the same conditions to generate images. The mean values of the digital signals were measured in the 35 locations of region of interest present in the images of the acrylic phantom. The images of the in-house-made phantom were then visually evaluated by five certified experts, who examined 22 clinical images taken with both PSPs while referring to a visual evaluation scale. Differences were detected in all the evaluated items: the short-term use PSP gave a higher rate than the long-term use PSP (p<0.01), suggesting that long-term use PSPs might adversely affect the results of diagnostic mammography.

[Examination of patient dose reduction in cardiovasucular X-ray systems with a metal filter].

In interventional X-ray for cardiology of flat panel digital detector (FPD), the phenomenon that exposure dose was suddenly increased when a subject thickness was thickened was recognized. At that time, variable metal built-in filters in FPD were all off. Therefore, we examined whether dose reduction was possible without affecting a clinical image using metal filter (filter) which we have been conventionally using for dose reduction. About 45% dose reduction was achieved when we measured an exposure dose at 30 cm of acrylic thickness in the presence of a filter. In addition, we measured signal to noise ratio/contrast to noise ratio/a resolution limit by the visual evaluation, and there was no influence by filter usage. In the clinical examination, visual evaluation of image quality of coronary angiography (40 cases) using a 5-point evaluation scale by a physician was performed. As a result, filter usage did not influence the image quality (p=NS). Therefore, reduction of sudden increase of exposure dose was achieved without influencing an image quality by adding filter to FPD.

[Hand hygiene during mobile X-ray imaging in the emergency room].

A hand hygiene behavior questionnaire and environmental survey were conducted regarding the mobile X-ray system used in the emergency room. As a result, among a total of 22 radiological technologists at this hospital who replied to the questionnaire, 18 wore disposable gloves when performing X-ray imaging using the mobile system. Among those 18, 11 were found to touch computed radiology (CR) consoles and HIS/RIS terminals while still wearing the gloves, thus creating the potential for spreading pathogens to other medical equipment and systems. According to the results of an environmental survey of the emergency imaging preparation room, the highest levels of bacteria were detected on CR consoles and HIS/RIS terminals. A possible reason for this is that these locations are not wiped down and cleaned as a part of routine cleaning and disinfection protocols, thus demonstrating the importance of cleaning and disinfection. Hand hygiene by medical personnel and appropriate cleaning and disinfecting of the working environment are important for preventing the spread of nosocomial infections. Radiological technologists are also required to take effective measures against infections in consideration of the high frequency of contact with both infected patients and patients susceptible to infections.

[Development of a prevention of body movement fixation appliance in leg digital subtraction angiography].

In the peripheral angiography to evaluate blood flow below the knee levels in patients with arteriosclerosis obliterans, a motion artifact occurs as a result of body movements of a patient in normal fixation. This sometimes makes a correct evaluation difficult. Therefore, we developed a fixed appliance which can restrain body movement without affecting image quality and blood flow in digital subtraction angiography of a leg. The appliance is filled with the styrofoam of 1 mm diameter in a sealed bag, after air is aspirated from inside the bag. The appliance is stiffened to fit the shape of the crus. We measured signal to noise ratio / contrast to noise ratio / a resolution limit by visual evaluation to examine the influence of the image before and after usage of this appliance. In addition, the blood velocity of the dorsalis artery in ultrasound was measured to examine the effect on the blood flow. As a result, the fixed appliance did not affect blood flow in peripheral angiography to evaluate the clinical significance, the usual 5-point evaluate scale was used. The scale was significantly improved (p <0.01) after usage of this appliance. The newly developed fixed appliance for digital subtraction angiography of a leg is useful to avoid motion artifacts in clinical settings.

[Improvement of body diffusion image using addition technique].

It is difficult to obtain body diffusion weighted images (BDWI) using MRI that does not support parallel imaging and multi-NEX in clinical usage. Therefore, we evaluated whether a multiple image additions technique on the workstation could improve BDWI image quality and be good for clinical use by considering SNR and image distortion. We added 2 to 5 images on the same slice location with changing FOV, slice thickness, or reconstruction matrix in the phantom studies, and confirmed SNR improvement under all conditions. We also confirmed that this addition technique did not affect image distortion. We found that in 16 of the 18 clinical cases, BDWI with 5 images addition match pathology and T2 weighted images. We believe that this addition technique in available in the clinical practice.

[The influence on the images of computed tomography caused by the use of artificial cranial reconstructive materials].

Various materials have been used for cranioplasty; however, these materials frequently produce artifacts that appear when examined with conventional radiography. Computed tomography (CT), in particular, detects high density artifacts near artificial bones, which is manipulated by increased noise, and limits diagnostic performance. The purpose of this study was to evaluate the extent and shape of the artifacts due to artificial cranial bones and to consider CT imaging parameters necessary for accurate recognition of structures under the materials. Four different artificial bone materials were evaluated in this study: hydroxyapatite with 1) 40% or 2) 50% porosity, 3) titanium plate, and 4) hydroxyapatite-polymethylmethacrylate composite (HA-PMMA). CT scanning was performed with standard clinical settings. Sample specimens were placed on the right side, under the artificial bones, and CT was performed to evaluate specimen visibility. We compared the artifacts created by the four bone types listed above, and measured the CT values of those materials. With ordinary scan settings, all the artificial bones revealed high-density artifact surrounding the materials, including the inability to accurately measure specimen thickness. The upper part of the specimen in contact with the artificial bones could not be distinguished from the artifact. The CT value in the medial aspect of the artificial bones increased more than the actual CT values. Of the four artificial bone materials studied, HA-PMMA produced the fewest artifacts. Description of the structures under the artificial bones can be improved by extending the window width to approximately twice that of normal settings.