For the resection of pulmonary ground glass opacity (GGO) or non-palpable nodule on video-assisted thoracic surgery (VATS), preoperative computed tomography (CT)-guided VATS marker pricking is usually performed. Recently, air embolisms after VATS marker pricking have been reported to be serious problems. The purpose of this study was to evaluate the usefulness of intraoperative cone beam CT images on VATS to avoid preoperative VATS marker pricking. The CT number of the both GGO and nodule indicate the range from −200 to −800 HU in general. We evaluated the detection ability of the lesion in seven elements and the simulated lungs. The result indicated that there was a linear equation of “y=1.0599×−2.1492” and the degree of correlation was “R2=0.9826” for the relationship between CT number and W number [voxel number in cone beam computed tomography (CBCT)]. Evaluation of low contrast resolution has been performed. The contrast noise ratios were 2.86 on CBCT and 1.50 on multi detector-row computed tomography (MDCT), while the relative contrast ratios were same both on CBCT and MDCT (0.19) as the lowest CT number (−700 HU). In clinical situation, four types of pulmonary lesions (pure GGO, mixed GGO, solid nodule, and cyst) were detected on MDCT, and intraoperative CBCT could identify all lesions as same configuration as on MDCT. The contrast noise ratio (CNR) and relative contrast ratio (RCR) could not admit the significant difference. In conclusion, the intraoperative CBCT can be used as a non-invasive image navigator for VATS, and the preoperative CT-guided VATS marker pricking can be avoided.
Purpose: Determination of X-ray fluoroscopy radiation dose and contrast with angiographic system automatically depending on the objects, and to control setting manually, which is difficult for the measurement of characteristics. Therefore, we examined the method to adjust the conditions of fluoroscopy and measured the input-output characteristics. Method: To adjust and fix the condition of fluoroscopy, the exposure adjustment area at the center of the irradiation field was moved to the left side and attached the copper plates to regulate the exposure dose. The area to measure the digital value was selected at the center of the irradiation field, and the dosimeter was placed at the right side of the area, which was selected to measure the digital value. To regulate the entrance dose progressively, the acryl plates were inserted into the irradiation field except for the exposure adjustment area. We obtained a characteristic curve from the measured dose and the digital value. Difference of lookup table (LUT), dose dependency, and tube voltage dependency were checked by the digital characteristic curves. Result: Each LUT showed different curves, but they all saturated with 4095, which is the maximum value of 12 bits. Dose dependency was measured as an increase in the permitted dose level with an increase in the setting dose. Tube voltage dependency improved with the tube voltage rises. Each characteristic curve became same by converting the relative exposure dose. As a result, measuring the shape of LUT would be possible. Conclusion: The method is useful for measuring the characteristic curve with the X-ray fluoroscopy of angiographic system.
Carotid artery plaques with high-signal intensity on T1 weighted image (T1 WI) are known to cause cerebral ischemic disease. Signal intensity ratio (SIR), which is calculated from T1 WI in the quantitative evaluation of plaque characterization have been used. However, the various sequences in T1 WI and difference in the sequences were utilized among institutions. Therefore, difference in sequence may influence SIR. The purpose of this study was to evaluate the optimization of T1 WI sequence in MR carotid plaque imaging. We directly compared four kinds of T1 WI imaging techniques, including inversion recovery (IR)-3 dimensional (3D) gradient echo (GRE), 3D fast spin echo (FSE), 2 dimensional (2D) FSE, 2D spin echo (SE), among different magnetic resonance imaging (MRI) scanner. As a result, the 2D SE method had the smallest difference in SIR. Even if 2D SE T1 WI uses a different MRI device, equal SIR is provided. Therefore, 2D SE is appropriate to evaluate the characteristics of carotid plaque.
Depiction of the fine vessel can provide useful preoperative information for patients with uterine cervical cancer. Although angiography can visualize vessels in detail, it is invasive. MR-angiography is a minimally invasive method to depict vessels, but the resolution of images is insufficient for preoperative evaluation. In this study, we used less invasive three-dimensional CT angiography (3D-CTA) and reconstructed images of adaptive iterative dose resolution 3D (AIDR 3D) with display field of view (D-FOV), which are suitable for arteries with large and small diameters, and created the fusion images. Created images allowed the observation of vessel branch in wide area compared with angiography, and it was less invasive. We evaluated the utility of 3D-CTA for visualizing fine vessels branching from uterine artery as preoperative evaluation for radial hysterectomy. 3D-CTA was obtained in nine patients. Conventional reconstruction and magnification reconstruction (D-FOV: 320‒360 mm, 150 mm) was made using arterial phase. Normal volume rendering image (N-VR) was made from conventional reconstruction image, and hybrid volume rendering image (H-VR) was made from conventional and magnification reconstruction image. Visual evaluation of each VR image was performed by 5 trained radiologists. A Wilcoxon rank sum test was performed for each result. No statistical significance was found in the visualization of vessels with large diameter (p=0.81), but statistical significance was detected in the visualization of the uterine artery and its ascending/descending branches (p<0.05). H-VR could visualize fine vessels clearer than N-VR, and H-VR could depict a vascular map including fine vessels in a large field. Therefore, H-VR could provide useful information for surgical operation. Additional depiction of vein and ureter could clearly visualize the anatomical relationship of each structure, and new clinical finding of anatomical relationship between uterine artery and ureter was suggested. This new clinical finding was useful in radical hysterectomy in which crossing site of the uterine artery and ureter is dissected. This method is simple to create and useful for various clinical surgery.
Purpose: Diagnosis for right-to-left shunt was determined by the assessment of shunt-rate, which was obtained by using 99 mTc-macroaggregated albumin. However, it is difficult to diagnose right-to-left shunt, using the normal level of shunt-rate measured by using conventional methods. To solve this problem, we investigated ourselves the normal level of shunt-rate. Method: We researched 20 patients with pulmonary embolism, and they didn’t have right-to-left shunt. We investigated three points for the normal level of shunt-rate. First, we examined the region of interest (ROI) area of the lungs to modify the upper level of gray scale. Second, we confirmed the difference between the whole visual field and body contour of the ROI area. Third, we examined the necessity whether we correct the background of whole body and the lungs. Result: We resulted three points. First, stable right-to-left shunt rate is got to set that the upper level of gray scale is 35%. Second, there is no significant difference between the whole visual field and body contour of the ROI area. Third, correcting background isn’t needed to get right-to-left shunt rate. The normal level of the shunt-rate was 12.6±2.8% in the condition. Conclusion: We are able to decide the optimal condition for the normal level of shunt-rate. It is important to evaluate the normal level of the shunt-rate fixed on each factor in each hospital.
We developed a phantom using a hollow-fiber hemodialyzer to evaluate the quantitative reliability of cerebral computed tomography (CT) perfusion. Our phantom consisted of a hollow-fiber hemodialyzer and a syringe-shaped X-ray device made up of resin. The phantom can give theoretical true values for cerebral blood volume, cerebral blood flow, and mean transit time. We compared the values measured in the phantom with predicted theoretical values. The purpose of the current report is to describe the theory and experimental technique used to obtain an absolute value in a phantom.