High-resolution computed tomographic angiography/computed tomographic cholangiography image fusion of the hepatobiliary system

The 3-dimensional image was excellent as a result of the fast scanning and narrow collimation using multidetector computed tomography (CT); and the parallel escalation in the capabilities of the workstation allow the use of CT angiography/CT cholangiography image fusion. We demonstrated the feasibility of fusion images of the hepatobiliary system. We believe that fusion images are extremely valuable for applications such as preoperative planning for hepatic and bile duct resection.     

Influence of cardiac function on image quality in coronary computed tomography angiography

PurposeTo evaluate the correlation between cardiac functional parameters and image quality in coronary computed tomography angiography (CCTA).Material and methodsSixty-six patients who underwent both CCTA and echocardiography were included. The coronary artery attenuation values and contrast-to-noise ratios (CNR) were measured in the proximal right coronary arteries (RCA) and left main (LM) trunk. Then, the averages of the mean values derived from RCA and LM were calculated. The cardiac output (CO), left atrial (LA) volume, and early mitral inflow velocity to mitral annular early diastolic velocity ratio (E/e′) were measured by echocardiography. The relationship of cardiac parameters with arterial attenuation and CNR were assessed by Pearson's correlation, Spearman's rank correlation and multivariable linear regression analysis adjusted for age, gender, body surface area and heart rate.ResultsThe coronary artery attenuation value was negatively correlated with CO (r = −0.30, p = 0.01) and LA volume (r = −0.37, p = 0.002). CNR was negatively correlated with LA volume (r = −0.4, p = 0.001) and E/e′ (r = −0.27, p = 0.03). These associations remained significant in the multivariable analysis.ConclusionCO and diastolic function had an impact on image quality of CCTA. Adjusting CCTA protocol may improve image quality in patients with known diastolic dysfunction or reduced cardiac output.     

Method of measuring modulation transfer function using metal wire in computed tomography

The current scanning parameters for computed tomography (CT) such as multi-detector row CT are becoming more complicated, and there are many cases in which the selected parameters directly affect image quality. Therefore, to evaluate the effectiveness and validity of the selected parameter, quantitative image quality evaluations are indispensable. Among the items of evaluation, modulation transfer function (MTF) is one of the most important in evaluating the resolution property. Several guidelines for performance evaluation for CT have been reported since the era of early CT diffusion. In those guidelines, it is recommended that the resolution property needs to be measured by the wire method, in which a phantom designed to support a thin metal wire along an axis perpendicular to the slice plane is used. However, the academic papers describing the wire method are so old that the detailed methodology corresponding to currently available CT specifications cannot be conducted. However, the fundamental principles are still effective. In this study, we examined the calculation method, phantom design and allocation, wire material, and other factors suitable for current CT specifications, and derived some recommendations from them.     

The use of contrast -- detail -- dose evaluation of image quality in a computed tomographic scanner.

Limiting-perception measurements of hole patterns in computed tomography reconstructions of a low-contrast phantom are used to generate contrast -- detail -- dose diagrams for various contrasts, hole diameters, dose, and system modulation transfer functions (MTF). These curves are then divided into MTF-dominated, transition, and noise-dominated regions. The low-contrast perceptibility and image noise are parameterized and compared. A limiting-perception factor is difined and is shown to be nearly independent of contrast, hole diameter, dose, and MTF in the noise-dominated region.     

Myocardial single-photon emission computed tomographic quality assurance

In this era of cost constraints in health care and the growing demand for cost-effective clinical strategies, the nuclear cardiologist is under increasing pressure to show clear evidence that myocardial imaging studies compete favorably with other modalities. This underlines the need for ensuring consistently high image quality and accuracy using optimally chosen standardized protocol. Nuclear medicine imaging has not yet reached the level of standardization, automation, and built-in quality control of imaging modalities such as ultrasound or x-ray computerized tomography, where the press of a button guarantees a consistent high-quality image. This is due to the large number of parameters and other factors affecting image quality that each individual operator still has to choose or be aware of before commencing imaging. Of crucial importance is ensuring the correct collection of the raw data. Processing can be repeated, but errors in the raw data, if detected at all, require repeating the entire study. These errors can cause artifacts that are difficult or impossible to recognize and are the major causes of incorrect reporting. Examples are a poorly prepared radiopharmaceutical, a poor injection, scatter from “hot” areas outside myocardium, an undetected change in the photopeak window, uniformity, or center of rotation, insufficient acquisition time, camera too far from the patient, etc. The first step to guarantee consistent image quality and accuracy is the preparation and strict implementation of a quality assurance program covering all the individual stages of the procedure starting from preparation of the radiopharmaceutical and ending with processing, display, and reporting. The next step is the standardization of optimally chosen protocols with maximization of automation. Rapid built-in automated software-driven equipment quality control checks should be developed. Finally, attenuation and scatter correction, gated singlephoton emission computed tomography, and the advent of digital cameras will no doubt improve quantitation and accuracy even further following clinical evaluation in close cooperation with manufacturers who have the incentive to accelerate all the above steps.     

The computed tomographic appearances of cherubism

The computed tomographic (CT) aspects of six cases of cherubism are described. Through its optimal representation of the lesions, CT enabled certain characteristics of this disease to be substantiated, namely, limitation of the process to the bones of the jaw and primarily superficial development of the mandibular lesions, coupled with an unusual mandibular condylar impairment. Moreover, the composition of this series permitted investigation of the condition in its several stages of progression.     

Radiation dose optimization in pediatric temporal bone computed tomography: influence of tube tension on image contrast and image quality

Introduction  

The purpose of this experimental study was to investigate the effect of tube tension reduction on image contrast and image quality in pediatric temporal bone computed tomography (CT).     

The posterior interparieto-peritoneal or retroperitoneal spaces. 2: Pathological x-ray computed tomographic image

The old reports about the interparieto-peritoneal spaces described particularly the renal space and its environment. The CT scan has modified the in vivo study of the extraperitoneal spaces (E.P.S.) and brought the question of the acquired knowledge up again. An anatomical research was performed in the first part of this study which describes the structures limited between the parietalis fascia and visceral peritoneal fascias. These are the true EPS which the main element is the propria fascia of Sappey (lateroconal fascia) and its anterior and posterior renal double layers. All these lamellar structures limits spaces variably infiltrated with fat tissue: the anterior pararenal space almost virtual, the posterior pararenal space which continues till the Bogros space and the anterior and posterior renal spaces of the renal compartment which the fat continues till the bladder and accompanies the ureter. The second part of this study precises some notions of general topography which are necessary for reading abnormal CT scan images. This part reminds the aortic and arterial general organization of the vertebrates as described by Mackay. It underlines the architectural importance of the three areas so defined: parietal or peripheral, intermediate or mesoblastic genitourinary and deep lateral or digestive endoblastic. These three areas corresponds to the three vascular aortic circles. It emphasized the importance to accept in practice the notion of visceral joining fascia which has been proved in adult people. The longitudinal architecture of the compartments is precise with respect to their appartenance to one among the three arterial arches of Mackay. What the anatomy suggest, the pathology can prove. Several pathological processes are studied on CT scan: large hemorrhagic or necrotic collections in acute pancreatitis, abnormalities or diseases of renal or adrenal compartments, extraperitoneal mesenchymomas, diseases of the psoas compartment. All these observations are analysed in order to explain anatomical and CT scan findings. This study refers not only to the oldest researches which are still valuable but also to the most recent controversies. All the questions are not solved using the clearest schemes.     

The optimal monochromatic spectral computed tomographic imaging plus adaptive statistical iterative reconstruction algorithm can improve the superior mesenteric vessel image quality

ObjectiveTo investigate the effect of the optimal monochromatic spectral computed tomography (CT) plus adaptive statistical iterative reconstruction on the improvement of the image quality of the superior mesenteric artery and vein.Materials and methodsThe gemstone spectral CT angiographic data of 25 patients were reconstructed in the following three groups: 70 KeV, the optimal monochromatic imaging, and the optimal monochromatic plus 40%iterative reconstruction mode. The CT value, image noises (IN), background CT value and noises, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and image scores of the vessels and surrounding tissues were analyzed.ResultsIn the 70 KeV, the optimal monochromatic and the optimal monochromatic images plus 40% iterative reconstruction group, the mean scores of image quality were 3.86, 4.24 and 4.25 for the superior mesenteric artery and 3.46, 3.78 and 3.81 for the superior mesenteric vein, respectively. The image quality scores for the optimal monochromatic and the optimal monochromatic plus 40% iterative reconstruction groups were significantly greater than for the 70 KeV group (P < 0.05). The vascular CT value, image noise, background noise, CNR and SNR were significantly (P < 0.001) greater in the optimal monochromatic and the optimal monochromatic images plus 40% iterative reconstruction group than in the 70 KeV group. The optimal monochromatic plus 40% iterative reconstruction group had significantly (P < 0.05) lower image and background noise but higher CNR and SNR than the other two groups.ConclusionThe optimal monochromatic imaging combined with 40% iterative reconstruction using low-contrast agent dosage and low injection rate can significantly improve the image quality of the superior mesenteric artery and vein.     

The influence of image resolution on the positron emission tomographic measurement of caudate glucose consumption

The aim of this study was to investigate the influence of image resolution on (a) relative and absolute values of caudate glucose consumption (rCMRGIc) determined by positron emission tomography (PET), and (b) the detection of significant differences in these metabolic values between groups of subjects. For this purpose, raw data of cerebral accumulation of fluorine-18 fluorodeoxyglucose (FDG) obtained in 11 normal subjects and in nine patients with unilateral thalamic infarction were reconstructed using filtered backprojection with four different cut-off frequencies (CFs), yielding images with a transaxial resolution of 5.7, 7.1, 8.9 and 11 mm (full-width at half-maximum; FWHM). Absolute values of caudate rCMRGIc decreased significantly by more than 30% over the range of image resolutions studied. Bilateral ratios of caudate rCMRGIc were insensitive to variations in image resolution. Levels of significance assessing the differences in mean metabolic values between patients and controls were all below 0.01. They were, however, slightly better at image resolutions of 7.1 and 8.9 mm than at a resolution of 5.7 mm. These data indicate (a) that relative values of rCMRGIc are better suited to compare quantitative results from different PET cameras than are absolute values, and (b) that the CF used for the filtered back-projection exerts a small but not negligible influence on levels of significance assessing differences in metabolic values between groups of subjects.     

一种调制传递函数的表达式

调制传递函数(modulation transfer function，MTF)是对线性影像成像系统或其环节空间频率转输特性的定量描述，是评价X线成像系统或器件性能的重要指标。MTF的测试方法得到了放射技术工作者的关注并应用于放射设备成像性能的测试。用对比度测试MTF时的表达式为输出调制度与输入制度之比，该方法的不足之处有二：其一是无法做出     

The computed tomographic findings of popliteal cysts

The computed tomographic (CT) findings of two popliteal cysts are presented, and the correlated anatomico-pathologic changes are discussed. The characteristic findings include thin, well-defined cyst wall, fluid density contents, central septum or septi, and medial popliteal location with mediocaudal extension. These findings, however, may vary due to herniation or rupture of the synovial membrane, gelatinous cyst contents, or metaplastic change of the cyst wall. Differential diagnoses include liposarcoma, popliteal aneurysm or hematoma, thrombophlebitis, xanthoma, fibrosarcoma, or other soft tissue tumors.     

Method of measuring modulation transfer function in computed tomography using slit method with air gap phantom

There are several methods for measuring modulation transfer function (MTF) in computed tomography (CT) images. The aluminum slit method, scanning a phantom consisting of a thin aluminum foil sandwiched by flat plastic slabs, is a standard method for measuring field of view (FOV) in clinical CT scan. But this method requires extreme caution when handling metal foil of high precision. Therefore, we devised a more simple method named air gap slit (AS) method. This new technique is based on the aluminum slit method but use air gap instead of metal foil between phantoms. The MTF was calculated from a reversed profile curve of air slit which indicated minimum CT number. The aim of this study was to investigate a possibility of AS method evaluating MTF. We investigated fluctuation of MTF and FOV in clinical CT scan compared with the aluminum slit method. The result showed that the fluctuation of MTF was caused by statistics noise and is more affected by a bone kernel than standard kernel when reconstructing. Also, the MTF value in AS method was slightly higher than in aluminum slit method and did not correspond with. AS method is a useful method for measurement of MTF in clinical CT scan. When we use this method, we have to take into consideration the noise influence of data.