scholarly journals Optimization of a protocol for contrast-enhanced four-dimensional computed tomography imaging of thoracic tumors using minimal contrast agent

2021 ◽  
Author(s):  
Hongya Dai ◽  
Dingqiang Yang ◽  
Lu Chen ◽  
Yibing Zhou ◽  
Xiaojing Wen ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agent ◽  
Flow Rate ◽  
Delay Time ◽  
Ct Images ◽  
Ct Scans ◽  
Target Delineation ◽  
4D Ct ◽  
Contrast Enhanced ◽  
Minimal Contrast

Abstract Purpose The accuracy of target delineation for node-positive thoracic tumors is dependent on both four-dimensional computed tomography (4D-CT) and contrast-enhanced three-dimensional (3D)-CT images; these scans enable the motion visualization of tumors and delineate the nodal areas. Combining the two techniques would be more effective; however, currently, there is no standard protocol for the contrast media injection parameters for contrast-enhanced 4D-CT (CE-4D-CT) scans because of its long scan durations and complexity. Thus, we aimed to perform quantitative and qualitative assessments of the image quality of single contrast-enhanced 4D-CT scans to simplify this process and improve the accuracy of target delineation in order to replace the standard clinical modality involved in administering radiotherapy for thoracic tumors. Methods Ninety consecutive patients with thoracic tumors were randomly and parallelly assigned to one of nine subgroups subjected to CE-4D-CT scans with the administration of contrast agent volume equal to the patient’s weight but different flow rate and scan delay time (protocol A1: flow rate of 2.0 ml/s, delay time of 15 s; A2: 2.0 ml/s, 20 s; A3: 2.0 ml/s, 25 s; B1: 2.5 ml/s, 15 s; B2: 2.5 ml/s, 20 s; B3: 2.5 ml/s, 25 s; C1: 3.0 ml/s, 15 s; C2: 3.0 ml/s, 20 s; C3: 3.0 ml/s, 25 s). The Hounsfield unit (HU) values of the thoracic aorta, pulmonary artery stem, pulmonary veins, carotid artery, and jugular vein were acquired for each protocol. Both quantitative and qualitative image analysis and delineation acceptability were assessed. Results The results revealed significant differences among the nine protocols. Enhancement of the vascular structures in mediastinal and perihilar regions was more effective with protocol A1 or A2; however, when interested in the region of superior mediastinum and supraclavicular fossa, protocol C2 or C3 is recommended. Conclusion Qualitatively acceptable enhancement on contrast-enhanced 4D-CT images of thoracic tumors can be obtained by varying the flow rate and delay time when minimal contrast agent is used.

scholarly journals The Effect of Contrast-enhanced Computed Tomography (CT) Scans on the Calculated Dose of Radiotherapy in a Thorax Phantom

2021 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Athar Ehtiati ◽  
Payman Hejazi ◽  
Mohsen Bakhshandeh ◽  
Ali Jabbary Arfaee ◽  
Eftekhar Rajab Bolookat ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Media ◽  
Ct Scan ◽  
Treatment Planning ◽  
Tumor Volume ◽  
Ct Scans ◽  
Contrast Enhanced ◽  
Enhanced Ct ◽  
Enhanced Computed Tomography ◽  
Contrast Enhanced Computed Tomography

Background: Despite the benefits of contrast-enhanced computed tomography (CT) scans in better tumor volume delineation, it can affect the accuracy of dose calculation in radiation therapy. This study examined this effect on a thorax phantom. Objectives: The influence of different variables including the concentrations of the Visipaque contrast media, tumor sizes, and CT scan energies on the dose measurement was examined. Methods: Transparent cylinders containing the contrast media were inserted in the lung area of the phantom and the CT scans were made. Non-enhanced CT scans were also acquired. Treatment planning using 2 opposite fields was performed on the CT scans and the doses were calculated in the treatment planning system. The results of the 2 sets of enhanced and non-enhanced CT scans were compared. Results: The correlation between concentration and the percentage of mean dose of the tumor volume was significant in 2 of the tumor sizes. The differences in the mean doses of the 2 plans were examined and more than 3% increase was observed in higher concentrations of the contrast media. Conclusions: According to this study, the suitable concentration of the contrast media administered and the CT scan energy should be considered. This would help to decrease the discrepancies between the calculated and delivered dose in radiotherapy treatments to a clinically acceptable level. The importance of time delays for CT scans after administration of the contrast media is emphasized.

scholarly journals Diagnostic value of contrast-enhanced ultrasound versus computed tomography for hepatocellular carcinoma: a retrospective, single-center evaluation of 234 patients

2020 ◽  
Vol 48 (6) ◽  
pp. 030006052093015 ◽  
Author(s):  
Vincent Schwarze ◽  
Constantin Marschner ◽  
Wiebke Völckers ◽  
Sergio Grosu ◽  
Giovanna Negrão de Figueiredo ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hepatocellular Carcinoma ◽  
Predictive Value ◽  
Diagnostic Value ◽  
Ct Scans ◽  
Liver Lesions ◽  
Contrast Enhanced Ultrasound ◽  
Single Center ◽  
Experienced Radiologist ◽  
Contrast Enhanced

Objective Hepatocellular carcinoma (HCC) is the most common cause of primary liver cancer. A major part of diagnostic HCC work-up is based on imaging findings from sonography, computed tomography (CT), or magnetic resonance imaging (MRI) scans. Contrast-enhanced ultrasound (CEUS) allows for the dynamic assessment of the microperfusion pattern of suspicious liver lesions. This study aimed to evaluate the diagnostic value of CEUS compared with CT scans for assessing HCC. Methods We performed a retrospective, single-center study between 2004 and 2018 on 234 patients with suspicious liver lesions who underwent CEUS and CT examinations. All patients underwent native B-mode, color Doppler and CEUS after providing informed consent. Every CEUS examination was performed and interpreted by a single experienced radiologist (European Federation of Societies for Ultrasound in Medicine and Biology level 3). Results CEUS was performed on all included patients without occurrence of any adverse effects. CEUS showed a sensitivity of 94%, a specificity of 70%, a positive predictive value of 93% and a negative predictive value of 72% for analyzing HCC compared with CT as the diagnostic gold standard. Conclusions CEUS has an excellent safety profile and shows a high diagnostic accuracy in assessing HCC compared with corresponding results from CT scans.

scholarly journals A Method for Tooth Model Reconstruction Based on Integration of Multimodal Images

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xinwen Zhou ◽  
Yangzhou Gan ◽  
Jing Xiong ◽  
Dongxia Zhang ◽  
Qunfei Zhao ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Orthodontic Treatment ◽  
Ct Images ◽  
Ct Scans ◽  
Reconstruction Method ◽  
Model Reconstruction ◽  
Crown Area ◽  
Computer Aided ◽  
Multimodal Images ◽  
Reconstructed Model

A complete digital tooth model is needed for computer-aided orthodontic treatment. However, current methods mainly use computed tomography (CT) images to reconstruct the tooth model which may require multiple CT scans during orthodontic progress, and the reconstructed model is also inaccurate in crown area. This study developed a tooth model reconstruction method based on integration of CT images and laser scan images to overcome these disadvantages. In the method, crown models and complete tooth models are first reconstructed, respectively, from laser scan images and CT images. Then, crown models from laser scan images and tooth models from CT images are registered. Finally, the crown from laser scan images and root from CT images were fused to obtain a new tooth model. Experimental results verified that the developed method is effective to generate the complete tooth model by integrating CT images and laser scan images. Using the proposed method, the reconstructed models provide more accurate crown than CT images, and it is feasible to obtain complete tooth models at any stage of orthodontic treatment by using one CT scan at the pretreatment stage and one laser scan at that stage to avoid multiple CT scans.

Turbinate atrophy evaluation in pigs by computed tomography

2003 ◽  
Vol 51 (4) ◽  
pp. 485-491 ◽  
Author(s):  
T. Magyar ◽  
F. Kovács ◽  
T. Donkó ◽  
H. Bíró ◽  
R. Romvári ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Nasal Cavity ◽  
Scoring System ◽  
Ct Images ◽  
Area Ratio ◽  
Ct Scans ◽  
Non Invasive ◽  
Visual Scoring ◽  
Ratio Determination ◽  
Visualisation Technique

Computed tomography (CT), a non-invasive visualisation technique was applied for imaging the bony structures of the nasal cavity of pigs, and compared to the traditional scoring system of turbinate atrophy in swine. Twenty-three 27-week-old pigs representing various stages of turbinate atrophy were used. Nasal structures were visually scored on CT scans and transversal cuts of the noses at the level of the first upper premolar teeth using the same scoring system in both cases. A tissue/air area ratio was also determined based on density differences. A highly significant correlation was found between visual scoring of CT images and transversal cuts of pig noses (r = 0.98, p < 0.0001) as well as between visual scoring of CT images and tissue/air area ratio determination (r = -0.82, p < 0.0001).

scholarly journals Perbandingan Penyangatan Senyawa Pengontras Nano Partikel Emas Dendrimer Poly (Amidoamine) Konsentrasi dan Delay Time Berbeda pada Hepar Tikus dengan Pemeriksaan Computed Tomography

2016 ◽  
Vol 1 (3) ◽  
pp. 131-137
Author(s):  
Indrarini Listyowati ◽  
Rista D Soetikno ◽  
Leni Santiana
Keyword(s):  
Computed Tomography ◽  
Statistical Analysis ◽  
Contrast Agent ◽  
Contrast Agents ◽  
Ct Scan ◽  
Rat Liver ◽  
Delay Time ◽  
P Value ◽  
Average Value ◽  
Targeted Contrast Agents

Background: Computed tomography (CT) is one of the diagnostic imaging tool that is most commonly available in hospitals today. But unlike Magnetic Resonance Imaging (MRI) and nuclear medicine imaging modalities, CT has not been considered as a molecular imaging modality because it does not have a specifc-targeted contrast agents. Diagnostic quality of CT scans can be improved by using specifc-targeted contrast agents. Gold nanoparticles (AuNPs) can be used as X-ray contrast agents that can overcome some of the limitations of the iodine-based contrast agents. Higher atomic numbers than iodine and its ability to be able to bind to the dendrimer support that AuNPS could be developed as a specifc-targeted contrast agents.Objectives: The purpose of this study was to determine the enhancement relationship of AuNPs-Poly(amido)amine in the rat liver with di?erent concentration and delay time on CT scans.Materials and Methods: This research is an experimental study with a statistical analysis to determine enhancement di?erences on rat liver given AuNPs-PAMAM with di?erent concentration and delay time. The samples were divided into 4 groups, each consisting of 6 rats. The independent variables in this study were the delay time and the concentration of AuNPs-PAMAM, the dependent variables was the enhancement on rat liver.Results: The results obtained showed that the average value enhancement of AuNPs-PAMAM is highest in 10 minutes delay time at a concentration of 1 mg/dL. Statistical analysis showed that there were signifcant di?erences between AuNPs-PAMAM contrast enhancement in the rat liver with di?erent concentration and delay time on CT scan with p-value less than alpha (0.000 <0.05).Conclusions: Concentration and delay time contribute to the average value enhancement of AuNPs-PAMAM contrast agent on CT scan. This new type of contrast agent can be further developed as a more specifc-targeted contrast agent for CT scan examination.

scholarly journals Gender differences in the maxillary sinus volume : a study using computed tomography scans of a sample of Tamil Nadu population

2016 ◽  
Vol 05 (03) ◽  
pp. 138-142
Author(s):  
N Muthukumaravel ◽  
K. Y. Manjunath
Keyword(s):  
Computed Tomography ◽  
Maxillary Sinus ◽  
Tamil Nadu ◽  
Ct Images ◽  
Ct Scans ◽  
P Value ◽  
Gender Determination ◽  
Maxillary Sinus Volume ◽  
Significant Difference ◽  
Maxillary Sinuses

Abstract Background and aims : Measurements of the maxillary sinus volumes in computed tomography (CT) scans can be used for determination of gender when other methods are inconclusive. Maxillary sinus dimension measurements are valuable in studying sexual dimorphism and can assist in gender determination. The radiographic images can provide adequate measurements for maxillary sinuses that cannot be approached by other means. The purpose of the present study was to determine and compare the volume of the maxillary sinus between males and females of Tamil Nadu region using CT scans. Materials and methods : This study was carried out by using CT images of head region of 100 males and 100 females who underwent CT scanning for indications other than the pathology of the maxillary sinuses. The CT images obtained were of patients between 20 to 50 years of age. The maxillary sinus volume of each side were calculated by using the following formula: Maximal width X Maximal height X Maximal depth X 0.5. Comparison of data between genders and sides was done. The statistical inference was derived by applying unpaired student "t" test and the p value was obtained (p value <.05 was considered statistical significant). Results: Oncomparison of males with females, the mean volumes of maxillary sinuses on each side (left and right) had shown a statistically significant difference (p<.OOOl ). The maxillary sinus volumes of the males were found to be significantly higher than that of the females. Among males, the average mean volume of maxillary sinuses (right + left) is 15.15 ± 0.45 cm3. Among females, the average mean volume of maxillary sinuses (right + left) is 12.77 ± 1.34 em' which is significantly lesser than that of the males. Conclusion : It can be concluded that the volumes of the maxillary sinuses of males are larger than those of the females and this difference is statistically significant. Maxillary sinus dimension measurements can assist in gender determination.

Computational Study of Computed Tomography Contrast Gradients in Models of Stenosed Coronary Arteries

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Parastou Eslami ◽  
Jung-Hee Seo ◽  
Amir Ali Rahsepar ◽  
Richard George ◽  
Albert C. Lardo ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Coronary Artery ◽  
Contrast Agent ◽  
Flow Velocity ◽  
Flow Rate ◽  
Coronary Flow ◽  
Computational Study ◽  
Cfd Modeling ◽  
Coronary Flow Velocity ◽  
Actual Flow Rate

Recent computed tomography coronary angiography (CCTA) studies have noted higher transluminal contrast agent gradients in arteries with stenotic lesions, but the physical mechanism responsible for these gradients is not clear. We use computational fluid dynamics (CFD) modeling coupled with contrast agent dispersion to investigate the mechanism for these gradients. Simulations of blood flow and contrast agent dispersion in models of coronary artery are carried out for both steady and pulsatile flows, and axisymmetric stenoses of severities varying from 0% (unobstructed) to 80% are considered. Simulations show the presence of measurable gradients with magnitudes that increase monotonically with stenotic severity when other parameters are held fixed. The computational results enable us to examine and validate the hypothesis that transluminal contrast gradients (TCG) are generated due to the advection of the contrast bolus with time-varying contrast concentration that appears at the coronary ostium. Since the advection of the bolus is determined by the flow velocity in the artery, the magnitude of the gradient, therefore, encodes the coronary flow velocity. The correlation between the flow rate estimated from TCG and the actual flow rate in the computational model of a physiologically realistic coronary artery is 96% with a R2 value of 0.98. The mathematical formulae connecting TCG to flow velocity derived here represent a novel and potentially powerful approach for noninvasive estimation of coronary flow velocity from CT angiography.

Limitations of Computed Tomography in the Investigation of Acoustic Neuromas

1977 ◽  
Vol 86 (4) ◽  
pp. 436-440 ◽  
Author(s):  
Stephen W. Parker ◽  
Kenneth R. Davis
Keyword(s):  
Computed Tomography ◽  
Ct Scan ◽  
Posterior Fossa ◽  
Positive Contrast ◽  
Clinical Suspicion ◽  
Ct Scans ◽  
Medium Size ◽  
Acoustic Neuromas ◽  
Contrast Enhanced ◽  
Rule Out

Seventy percent of 80 surgically proven acoustic neuromas were visualized on preoperative computed tomography (CT) scans. Many more tumors were seen on contrast enhanced scans than on unenhanced scans (55 vs 25). No intracanalicular tumors and only one of 15 tumors less than 2 cm in size were visualized on CT scan. Most medium size tumors (2.0–3.0 cm) and all large tumors (>3.0 cm) were visualized on CT scan when optimal technique was used. Positive CT scans often replace more invasive diagnostic studies in the investigation of acoustic neuromas. Negative scans do not rule out tumors as intracanalicular, and small tumors are usually not visualized with current techniques. If there is clinical suspicion of an acoustic neuroma, positive contrast posterior fossa cisternography should be done when the CT scan is negative.

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