MDCT Scanner Research Articles

An Analysis of Doses and Images of Mobile CT of High-Energy Electromagnetic Wave Area

The demand in medical field for Mobile Computed Tomography in high-energy electromagnetic area is exploding. To measure the distribution of exposure doses in abdomen inspection, this study placed 2 glass dosimeter elements on the entry point and exit point, respectively, 2-3 cm above the navel, the central point of abdominal inspection, and measured exposure doses in different parts. And, to reduce measurement errors, MDCT scanning was done 5 times. Acquired images were analyzed qualitatively to identify usefulness in medical treatment. Qualitative analysis of images was done about image contrast, lesion discovery rate, and clarity of border. Five specialists (2 medical doctors specializing radiology and 3 radiologists with working experiences over 10 years) were asked to classify the results on the 5-point scale (1 - very poor; 2 - poor; 3 - average; 4 - good; 5 - very good). In skull CT scanning, exposure doses measured with glass dosimeter were as follows: 21.4 ± 0.43 mGy by 4-MDCT; 13.7 ± 0.43 mGy by 128-MDCT; 5.02 ± 0.19 by Mobile CT, which shows that Mobile CT requires relatively lower dose to get meaningful images in diagnosis (P 0.05). In skull CT scanning, the images acquired from MDCT and Mobile CT were graded on the 5-point Likert scale: 4-MDCT images got 3.50 point; 128-MDCT images got 4.43 point; Mobile CT images got 4.21 point. The 128-MDCT got the highest point, followed by 4-MDCT and Mobile CT. The difference was statistically significant (P 0.05). The above findings show that Mobile CT is good for getting high-quality image and reducing radiation exposure doses. It seems that more hospitals will use Mobile CT.

Computed Tomography Evaluation of Blunt Abdominal Injury

Background: Unlike penetrating abdominal trauma, where management is largely determined clinically, the diagnosis of blunt abdominal injury by clinical examination is unreliable, particularly in patients with a decreased level of consciousness.Plain abdominal radiography has limited role in the assessment of blunt abdominal trauma, although some authorities continue to advocate its use. CT scan’s main advantage is the ability to detect arterial contrast extravasation, uncontained or as a pseudoaneurysm, which predicts the need for surgery or angioembolisation. The aim is to study computed tomography evaluation of blunt abdominal injury. Subjects and Methods: The present study was conducted in the Department of Radiology of the medical institution. For the study, we used abdomen CT scan reports of 100 patients with BAT, who were stable enough to undergo radiological investigation. The patients included 66 males and 34 females. All CT scans were obtained with a 16 slice MDCT Scanner (Siemens). All patients received intravenous bolus of iodinated contrast agents. Individual organ injuries were graded according to the American Association for the Surgery of Trauma (AAST - OIS) injury scoring scale. The overall imaging findings were analysed for their role in guiding the therapeutic options, whether conservative or surgical. Results: Total number of patients included in the study was 100. The mean age of patients was 41.97 years. Number of male patients was 66 and number of female patients was 34. For the mode of injury, other miscellaneous causes were most common in out study group followed by road traffic accidents. It was observed that OIS grade II patients were 19, OIS grade III patients were 29, OIS grade IV patients were 12 and OIS grade V patients were 10. The highest proportion of conservatively managed patients were seen in OIS grade II patients. Conclusion: Within the limitations of the present study, it can be concluded that CT scan for blunt abdominal injury is a reliable and accurate method for diagnosis. It has all the qualities to make it a gold standard for initial investigation of choice for blunt abdominal injury patients.

Organ Doses, Effective Dose, and Cancer Risk From Coronary CT Angiography Examinations.

OBJECTIVE. The purposes of this study were to determine organ and effective doses and to estimate the risk of exposure-induced cancer death (REID) associated with coronary CT angiography (CCTA) examinations. SUBJECTS AND METHODS. CCTA examinations were performed in three stages: calcium score, monitoring, and cardiac phases for all patients. Effective dose was calculated using two methods. The first was based on the scanner-derived dose-length product, and the second entailed use of an organ and effective dose calculator software application. Organ doses were calculated on the basis of the tissue weighting factors of International Commission on Radiation Protection report 103. REID values were assessed with a cancer risk estimator software application. RESULTS. The study included 185 patients (95 men, 90 women). For women, breast doses were high at 52.04 ± 14.08 mGy. The mean effective dose in the women was greater than that in the men (24.05 vs 16.30 mSv, p < 0.05). The mean REID values in patients undergoing CCTA with a 64-MDCT scanner were 13.4 per 10,000 men (1 in 746) and 19.6 per 10,000 women (1 in 508). The REID values were considerably higher for the younger women. CONCLUSION. The results of this study will help referring physicians justify requesting CCTA examinations by considering their benefits for diagnosis on the one hand and awareness of the risk of radiation-induced cancer on the other. In the case of CCTA scans that are properly justified by clinical indication, patients and physicians should not be concerned about the radiation risks.

Vidian canal and sphenoid sinus: an MDCT and cadaveric study of useful landmarks in skull base surgery.

To present the anatomical variations of vidian canal (VC) and sphenoid sinus (SS), relative to other anatomical landmarks of skull base area, which may be helpful for safer surgical approach to this area. MDCT scans (128-row MDCT system) of 90 patients (mean age 62years) and six cadaveric heads were studied, and the following parameters were evaluated: mean length and types of VC, distance between VC and foramen rotundum (FR) and optic canal (OC), position of the VC regarding the lateral pterygoid plate (MPTG) and petrous ICA, pneumatization of SS, position of intrasinus septum regarding ICA and OC, bone dehiscence and protrusion of ICA and OC into SS. Six cadaveric heads underwent MDCT and endoscopic dissection, and the type and length of VC were evaluated. The statistical significance was assessed using Chi-square (χ2) test. Significance level was set at p < 0.05. A statistical analysis was performed between the measurements at both sides, as well as between measurements in MDCT and dissection of the six cadaveric heads. Statistically significant difference was found between right and left sides in the horizontal and vertical distances between FR and VC, as well as between VC and OC. Also, there was a statistically positive correlation between type II of VC and lateral pneumatization on the right side. There was not statistically significant difference concerning VC type and length between MDCT and dissection measurements. Surgeons addressing skull base surgery must be familiar with the anatomical and positional variations of VC and SS in the preoperative CT images so as to avoid serious complications during surgery.

Organ-based Tube-current Modulation Applied on Different MDCT Scanners: Reduction in the Radiation Dose to the Eye Lens at Head CT

Organ-based tube current modulation (OB-TCM) techniques, which are provided by three vendors, reduces the radiation dose to the lens of the eyes by decreasing the tube current, when the X-ray tube passes over the anterior surface of critical organs. However, the characteristics of dose modulation of these techniques are different. The purpose of this study was to understand the performance characteristics of OB-TCM technique of each computed tomography (CT) vendor at head CT. We used three CT scanners (SOMATOM Definition Flash; Siemens Healthcare, Revolution CT; GE Healthcare, and Aquilion ONE Genesis Edition; Canon Medical Systems). We measured the radiation dose to the lens surface as evaluation of radiation dose reduction and measured the image noise as index of image quality. We measured the radiation dose rate in the air for analysis of the characteristics of dose modulation in each OB-TCM. When applying OB-TCM, the radiation doses for the lens surface were decreased by 28%, 22%, and 25% for Siemens, GE, and Canon CT scanners, respectively, and the image noise level was increased by 5.6%, 8.5%, and 15.1% for Siemens, GE, and Canon CT scanners, respectively. The characteristics of dose modulation in each OB-TCM were also confirmed by measured the radiation dose rate. We confirmed that each OB-TCM has different influence on image quality and radiation doses for lens surface, due to the different characteristics of dose modulation for each CT vendor.

MDCT angiographic findings of various congenital pulmonary artery anomalies in pediatric patients

BackgroundCongenital pulmonary artery anomalies are variable and need proper diagnosis and treatment. CT angiography with multiplanar reconstruction has the main role in the assessment of these anomalies and this non-invasive method should be the method of choice for preoperative planning and postoperative follow up.The aim of the study is to assess the value of MDCT in the detection of pulmonary arteries anomalies in the pediatric population with complex congenital heart disease in conjunction with echocardiography as an alternative to conventional angiography and to determine the superiority of MDCT in the assessment of other abnormalities such as airway anomalies.ResultsIn our retrospective study, 52 patients (28 male and 24 females, aged 1 day to 4 years: mean age 2 years) were examined with contrast-enhanced CT. CT examinations were done using a 128-section CT scanner (Siemens Somatom Definition AS) using non-ionic iodinated contrast media. 2D and 3D reconstructions were performed. The correlation was made with echocardiograms. All imaging studies were reviewed. The echo was done to all patients. Surgery and/or catheter angiography performed to all patients, their findings were reviewed and compared to CTA findings. Other abnormalities such as congenital airway anomalies are detected using axial MDCT images and reconstructed imaging techniques.MDCT was accurate in revealing pulmonary artery anomalies. The commonest pulmonary artery anomaly was atresia, stenosis then hypoplasia. These anomalies may be isolated or associated with other congenital heart diseases. In the current study, MDCT could diagnose all cases of pulmonary arterial anomalies with 96% sensitivity, 100% specificity, 98% accuracy, 100% positive, and 94% negative predictive values. CT scans provide accurate information to assess complex spatial relationships of vascular airway compression frequently associated with CHD in the pediatric population.ConclusionMDCT scanner can be an alternative to diagnostic conventional angiography for the non-invasive assessment of the pulmonary artery. Higher quality multiplanar and 3D reconstruction achieved by the MDCT scanners offer a rapid, reliable and non-invasive technique that can be used for the evaluation and preoperative assessment of thoracic vascular and extra-vascular anatomy in infants and children with suspected congenital heart disease. CT technologies are constantly developing collaboration between radiologists, pediatric cardiologists, and anesthesiologists, which is essential for improving CT performance.

Prognostic value of the coronary artery calcium score in suspected coronary artery disease: astudy of 644 symptomatic patients.

AimThe long-term value of coronary artery calcium (CAC) scanning has not been studied extensively in symptomatic patients, but was evaluated by us in 644 consecutive patients referred for stable chest pain.MethodsWe excluded patients with a history of cardiovascular disease and with a CAC score of zero. CAC scanning was done with a 16-row MDCT scanner. Endpoints were: (a) overall mortality, (b) mortality or non-fatal myocardial infarction and (c) the composite of mortality, myocardial infarction or coronary revascularisation. Revascularisations within 1 year following CAC scanning were not considered.ResultsThe mean age of the 320 women and 324 men was 63 years. Follow-up was over 8 years. There were 58 mortalities, while 22 patients suffered non-fatal myocardial infarction and 24 underwent coronary revascularisation, providing 104 combined endpoints. Cumulative 8‑year survival was 95% with CAC score <100, 90% in patients with CAC score >100 and <400, and 82% with CAC score ≥400 Agatston units. Risk of mortality with a CAC score >100 and ≥400 units was 2.6 [95% confidence interval (CI) 1.23–5.54], and 4.6 (95% CI 2.1–9.47) respectively. After correction for clinical risk factors, CAC score remained independently associated with increased risk of cardiac events.ConclusionsRisk increased with increasing CAC score. Patients with CAC >100 or ≥400 Agatston units were at increased risk of major adverse cardiac events and are eligible for preventive measures. CAC scanning provided incremental prognostic information to guide the choice of diagnostic and therapeutic options in many subjects evaluated for chest pain.

304. Hepatocellular Carcinoma Occurs Frequently and Early After Treatment in HCV Genotype 3 Infected Persons Treated with DAA Regimens

BackgroundTreatment of HCV with directly acting antiviral agents (DAAs) is associated with a significant reduction in cardiovascular, metabolic and cancer risk. However, there are conflicting data regarding the risk of hepatocellular carcinoma (HCC) after DAA treatment. Risk of HCC in HCV genotype 3 infected persons after DAA therapy is not well known.MethodsWe prospectively studied HCV-infected persons initiated on treatment between October 2014 and March 2017 at two centers in Pakistan. All persons were free of HCC at study initiation. The occurrence of HCC was confirmed based on radiologic findings on a triphasic CT on 64 slice MDCT scanner. The treatment regimen was at the discretion of clinical care providers, taking into account the national guidelines and patient preferences. Patients were followed for 24 weeks after the completion of therapy. Informed consent was obtained from all participants.ResultsA total of 662 persons were initiated on treatment. Median age (IQR) was 50 (41, 57) years and 48.8% were male. At baseline, 49.4% were cirrhotic with 90% of cirrhotics having compensated cirrhosis. 91% were genotype 3 and SVR was attained in 91.9%. Treatment regimens used were: Sofosbuvir (SOF)/ribavirin (RBV)/pegylated interferon (PEG-IFN), 25.2%; SOF/RBV, 62.4%; SOF/RBV/daclatasavir (DCL), 10.6%; SOF/DCL, 2.0%. Incident HCC was detected in 42 patients (12.8%) in the six month period after treatment completion, and was exclusively observed in those with cirrhosis. In multivariable Cox regression analysis, SVR was associated with a reduction in HCC risk (HR, 95% CI: 0.35, 0.14,0.85) while SOF/RBV/DCL regimen (compared with SOF/RBV/PEG-IFN) was associated with an increased risk of HCC (HR, 95% CI: 17.32, 2.14,140.36). In K-M plots by treatment regimen, those treated with SOF/RBV, SOF/RBV/DCL, or SOF/DCL regimens had shorter HCC-free survival compared with those treated with a SOF/RBV/PEG-IFN regimen. (See figure)ConclusionIn a predominantly genotype 3 cohort, incident HCC occurs commonly and early after treatment completion, and exclusively in those with pretreatment cirrhosis. SVR reduces but does not completely eliminate the risk of HCC. Treating HCV-infected persons before the development of cirrhosis may reduce future risk of HCC. Disclosures All authors: No reported disclosures.

Radiation Dose for Multiregion CT Protocols: Challenges and Limitations.

OBJECTIVE. The purpose of this study was to devise a method for classification of individual chest and abdomen-pelvis CT doses for multiregion CT. MATERIALS AND METHODS. A retrospective analysis of volume CT dose index (CTDIvol) and dose-length product (DLP) associated with chest (150 adult patients), abdomen-pelvis (150 patients), and multiregion combined chest-abdomen-pelvis CT (210 patients; 60 single-run chest-abdomen-pelvis CT; 150 split-run with separate chest and abdomen-pelvis CT). All 510 CT examinations were performed with one of four MDCT scanners (64-, 64-, 128-, 256-MDCT). CTDIvol, DLP, and scan length were recorded. Scan lengths were obtained for these 510 CT examinations and for an additional 7745 examinations of patients at another institution. Data were analyzed by ANOVA and ROC analysis. RESULTS. The respective DLPs (chest, 258-381 mGy · cm; abdomen-pelvis, 360-433 mGy · cm; single-run chest-abdomen-pelvis, 595-636 mGy · cm) and scan lengths (chest, 31-33 cm; abdomen-pelvis, 45-46 cm; single-run chest-abdomen-pelvis, 63-65 cm) for chest, abdomen-pelvis, and multiregion combined chest-abdomen-pelvis CT were significantly different (p < 0.0001). For split-run, chest-abdomen-pelvis CT, scan lengths and dose indexes for individual body regions were not different from those of single-body-region CT (p > 0.05). ROC analysis of chest and abdomen examinations showed an ideal scan length threshold of 38 cm to differentiate abdomen-pelvis CT from chest CT with accuracy of 97.39% and an AUC of 0.9764. CONCLUSION. Despite interscanner variabilities in CT radiation doses, shorter scan length for chest than for abdomen-pelvis CT enables accurate binning of radiation doses for split-run combined chest-abdomen-pelvis CT.

Quantification of Pubic Symphysis Metamorphosis Based on the Analysis of Clinical MDCT Scans in a Contemporary Malaysian Population.

Forensic age estimation methods are biased to sex and population; in general, accuracy is reduced when applied to foreign populations. This study assessed the accuracy of the Suchey-Brooks method in contemporary Malaysian individuals and aimed to formulate population-specific standards. Multi-detector computed tomography scans of 355 individuals (165 male; 190 female) of 15-83years of age were reconstructed using 3D-volumetric rendering in RadiAnt. Pubic symphyseal phase, bias, inaccuracy, and percentage correct age classifications are examined. Transition analysis was used to develop age estimation standards. High observer agreement (κ=0.763-0.832) and a positive relationship between age and pubic symphyseal phase (r=0.884-0.90) were demonstrated. Mean inaccuracies were 8.62 and 8.95years for males and females, respectively; overall correct classification was 97.8%. Transition ages between phases in males were 18.79, 23.29, 28.85, 43.64, and 61.15years; in females, the corresponding data were 19.77, 22.53, 32.62, 41.85, and 57.39years.

Improved enhancement in CT angiography with reduced contrast media iodine concentrations at constant iodine dose

The study objective is to investigate the impact of a wide range of contrast media (CM) iodine concentrations on CT enhancement at constant total iodine dose (TID) and iodine delivery rate (IDR). Seven injection protocols, based on different iodine concentrations ranging from 120 to 370 mg I/mL, were assessed on 4 minipigs at a constant TID of 320 mg I/kg and IDR of 0.64 g I/s. Dynamic images were acquired on a clinical 64-slice MDCT scanner for 120 s with the abdominal aorta, vena cava inferior and liver parenchyma in the field-of-view. Maximal enhancement, time-to-peak and peak width were assessed. The enhancement curve characteristics were correlated with CM iodine concentration. In particular, CM with lower iodine concentrations yielded a significant increased maximal enhancement and peak width compared to the standard-of-care concentrations: e.g. in the aorta, 245 HU maximal enhancement and 9.2 s peak width with the 320 mg I/mL iodine concentration increased to 291 HU and 16.1 s with 160 mg I/mL. When maintaining a constant TID and IDR, by compensating injection rate and volume, injection of a CM with reduced iodine concentration results in a diagnostically beneficial higher maximal enhancement and longer enhancement peak duration.

Usefulness of diluted contrast medium for test-scanning of infants scheduled for contrast-enhanced cardiovascular computed tomography angiography.

To compare the ability of test scans with undiluted and diluted contrast medium (CM) to predict contrast enhancement (CE) on cardiovascular CT angiography (CCTA) images of infants. We divided 120 consecutive infants who had undergone CCTA on a 64-MDCT scanner into two equal groups. In one group, the test bolus consisted of undiluted CM [protocol 1 (P1): injection volume = total body weight × 1.2 ml, injection time 5 s], in the other (P2) it was total body weight × 4.0 ml (CM 15%, saline 85%, injection time 16 s). CE on the test scans was recorded on a 3-point visual scale. We investigated the relation for CE in the pulmonary artery and ascending aorta between the P1 or P2 test scans and CCTA images. While peak CE was observed on all test scans performed with P2, in approximately 10 % of test scans obtained under P1, peak CE was not visualized. There was a strong positive linear correlation for CE of the pulmonary artery and ascending aorta on P2 images (r = 0.61 and r = 0.63, p < 0.01); under P1 the correlation was weak (r = 0.26 and r = 0.33, p < 0.01). Test-scanning with diluted CM revealed the optimal CE peak time and was useful for predicting CE on CCTA scans of the pulmonary artery and ascending aorta in infants with congenital heart disease. Diluted test scans help to select the optimal scan parameters for the CCTA study of infants by using contrast-to-noise-based scanning.

Geometric morphometrics on juvenile crania: Exploring age and sex variation in an Australian population

For medico-legal forensic practitioners the identification of unknown remains is an important part of any investigation, often predicated on having accurate estimations of age and sex. In considering the specific skeletal elements available to facilitate such biological information, the cranium is frequently targeted for analysis, as it exhibits marked traits of sexual dimorphism, and also has a predictable pattern of growth. There are, however, instances where it may not be possible to estimate skeletal sex, especially in the juvenile skeleton. There is still considerable uncertainty surrounding the age at which the human cranium is quantifiably dimorphic. The aim of the present study is to explore age and sex variation in three-dimensionally reconstructed MDCT scans of the juvenile cranium. The study sample comprises 152 juvenile crania from a Western Australian population; a total of 52 three-dimensional landmarks are acquired and analyzed using Procrustean geometric morphometrics. Group discrimination is assessed between sexes and across age classes.Results demonstrate that sexual dimorphism and age variation is discernible through geometric morphometric analysis of form, size and shape. Relative to sex and age, size is found to be generally equivalent to, or even more accurate than, shape data. There is little quantifiable sexual dimorphism in individuals younger than 12years of age with most variation related to age; discrimination improves with increasing age, with average hit rate (HR) values increasing from just over 50% (52–58%) to more than 90% (93–94%) accuracy at 18years. In contrast, differences between contiguous age classes follow the opposite trend and tend to be larger in prepubertal groups, while becoming progressively smaller in older age classes.This study demonstrates that simple linear interlandmark distances describing overall cranial size may provide a simple option for preliminary classifications of age and sex in skeletal remains of forensic interest. However, although recombining size and shape to perform analyses using form generally does not appreciably improve predictive accuracy, it potentially contributes to increased confidence in group assessment (especially for sex) and thus offers a promising, albeit complex, type of information to discriminate groups based on cranial size and/or shape.

Quantification of secondary dentin formation based on the analysis of MDCT scans and dental OPGs in a contemporary Malaysian population

Quantification of secondary dentin formation based on the analysis of MDCT scans and dental OPGs in a contemporary Malaysian population

Dependency of prescribed CT dose on table height, patient size, and localizer acquisition for one clinical MDCT

PurposeThe purpose of this study was to quantify the effect that table height, patient size, and localizer acquisition order may have on AEC prescribed dose. Method and materialsThree phantoms were used for this study: the Mercury Phantom, acrylic sheets, and an anthropomorphic phantom. A lateral (LAT) and a posterior-anterior (PA) localizer was acquired for each phantom at different table heights on a MDCT scanner (GE Discovery CT750 HD). AEC scan acquisitions were prescribed for each combination of phantom, localizer orientation, and table height ±4 cm with the center position; the displayed CTDIvol was recorded. Based on the institutional dose monitoring program, the relationship between change in CTDIvol and change in table height were studied for LAT and AP localizers for clinical exams. ResultsFor all phantom scans based on the PA localizer, the percent change in ranged between −18% and 42% for table heights 4 cm below and above proper centering; while for the LAT localizer, the percent change in CTDIvol from ideal were no greater than 12% different for ±4 cm differences in table height. Change in CTDIvol and change in table height displayed a strong linear relationship for AP localizer exams (P = 0.002), and weak correlation for LAT localizer exams (P = 0.12). ConclusionsSince uncertainty in vertical patient positioning is inherently greater than lateral positioning, the LAT localizer should be utilized to precisely and reproducibly deliver the intended amount of radiation prescribed by CT protocols.

The evaluation of coronary artery-to-pulmonary artery fistula in adulthood on 256-slice CT coronary angiography: Comparison with coronary catheter angiography and transthoracic echocardiography

ObjectiveTo review the imaging features of coronary artery-to-pulmonary artery fistula (CPAF) on CT coronary angiography (CTCA) and evaluate its diagnostic performance compared with coronary catheter angiography (CCA) and transthoracic echocardiography (TTE). Materials and methodsWe retrospectively reviewed with a diagnosis of CPAF from among 19855 consecutive CCTA performed with 256-slice MDCT scanner for suspected coronary artery disease. CT images were evaluated for – origin, number, size and course (tubular/worm-like dilation/significant aneurysm formation/wall attachment sign) of fistula vessels, drainage site, drainage site imaging features (pierced sign, isodensity sign, smoke sign, jet sign), and main pulmonary artery (MPA) enlargement. 25 patients of CPAF also underwent CCA and 47 patients underwent TTE. ResultsThere were 72 patients with CPAF (0.36%) in our study, of which 44 were men and 28 were women, with mean age of 55.8 ± 13.2 years (range 22–85 years). CPAF originated from conus artery, left anterior descending artery (LAD), combined conus artery and LAD in 55, 67, 50 cases, respectively. Tubular dilation, worm-like dilation and aneurysm was seen in 14, 58 and 35 cases, respectively. Wall attachment sign was noted in 69 cases. All the cases demonstrated only a single drainage site, with left lateral wall, left anterolateral, anterior, right lateral and right anterolateral walls of MPA in 44, 21, 5, 1 and 1 cases, respectively. The mean diameter of the fistula drainage site was 2.6 ± 1.3 mm. Pierced sign, jet sign, smoke sign, isodensity sign was seen in 72, 46, 41 and 24 cases, respectively. MPA enlargement was seen in 20 patients. CCA showed CPAF in only 20 cases among 25 patients; while TTE showed CPAF in only 9 patients among 47 patients. ConclusionCTCA is competent in detecting and characterizing CPAF with an excellent diagnostic performance as the first imaging modality of choice, which is valuable for giving a distinct and intuitive explanation to patients and physicians and making an objective and exact assessment for further management.

Extent of enhancement on multiphase contrast-enhanced CT images is a potential prognostic factor of stage I-III colon cancer.

By evaluating extent of tumour enhancement on preoperative contrast-enhanced MDCT, we aimed to establish an imaging-based model to predict cancer-specific survival in stage I-III colon cancer. A total of 548 stage I-III colon cancer patients who underwent curative resection from 2007 to 2013 were retrospectively included and divided into primary cohort and validation cohort according to admission time. The attenuation coefficient of each colon cancer was measured on the workstation by drawing the ROI in CT images. The enhancement ratio was calculated using maximum tumour attenuation value in triphasic MDCT scanning divided by the minimum. Patients were divided into low/high-enhancement groups according to the optimal cut-off value derived from time-dependent ROC curve. Kaplan-Meier method and COX regression analysis were adopted to evaluate prognostic value of variables. A nomogram for prognosis was conducted on the basis of a multivariate Cox proportional hazard model. No significant differences were observed in age, sex, pTNM stage, perioperative chemoradiotherapy, serum CEA, tumour size, tumour localisation and histologic type between low- and high-enhancement groups. The high-enhancement group had a significantly shorter cancer-specific survival rate (69.5%) than the low-enhancement group (85.9%) (p < 0.001). Subgroup analysis indicated that high-enhancement state was closely associated with increased risk of colon cancer mortality in stage I (p = 0.033), stage II (p = 0.002) and stage III (p = 0.014). Cox regression analysis indicated the extent of enhancement was an independent prognostic factor (HR 2.258, 95% CI 1.476-3.455; p < 0.001). The extent of tumour enhancement on MDCT can serve as a potential risk factor for stage I-III colon cancer. • Survival rates of stage I-III colon cancer vary widely even within the same stage. • Prognostic value of the extent of tumour enhancement on MDCT was assessed. • The high-enhancement group had a significantly shorter cancer-specific survival rate.

Quantitative accuracy of CT numbers: Theoretical analyses and experimental studies.

The CT number accuracy, that is, CT number bias, plays an important role in clinical diagnosis. When strategies to reduce radiation dose are discussed, it is important to make sure that the CT number bias is controlled within an acceptable range. The purpose of this paper was to investigate the dependence of CT number bias on radiation dose level and on image contrast (i.e., the difference in CT number between the ROI and the background) in Computed Tomography (CT). A lesion-background model was introduced to theoretically study how the CT number bias changes with radiation exposure level and with CT number contrast when a simple linear reconstruction algorithm such as filtered backprojection (FBP) is used. The theoretical results were validated with experimental studies using a benchtop CT system equipped with a photon-counting detector (XC-HYDRA FX50, XCounter AB, Sweden) and a clinical diagnostic MDCT scanner (Discovery CT750 HD, GE Healthcare, Waukesha, WI, USA) equipped with an energy-integrating detector. The Catphan phantom (Catphan 600, the Phantom Laboratory, Salem, NY, USA) was scanned at different mAs levels and 50 scans were performed for each mAs. The bias of CT number was evaluated for each combination of mAs and ROIs with different contrast levels. An anthropomorphic phantom (ATOM 10-year-old phantom, Model 706, CIRS Inc. Norfolk, VA, USA) with much more heterogeneous object content was used to test the applicability of the theory to the more general image object cases. Both theoretical and experimental studies showed that the CT number bias is inversely proportional to the radiation exposure level yet linearly dependent on the CT number contrast between the lesion and the background, that is, . The quantitative accuracy of CT numbers can be problematic and thus needs some extra attention when radiation dose is reduced. In this work, we showed that the bias of the FBP reconstruction increases as mAs is reduced; both positive and negative bias can be observed depending on the contrast difference between a targeted ROI and its surrounding background tissues.

Radiation exposure and coronary artery calcium scans in the society for heart attack prevention and eradication cohort.

Coronary artery calcium (CAC) scoring is used in asymptomatic patients to improve their clinically predicted risk for future cardiovascular events. Current CT protocols seek to reduce radiation exposure without diminishing image quality. Reported radiation exposure remains widely variable (0.8-5mSv) depending on the type of protocol. In this study, we report the radiation exposure of CAC scoring from the Society for Heart Attack Prevention and Eradication (SHAPE) early detection program cohort sites, which spanned multiple centers using 64-MDCT (multi-detector computed tomography) scanners. We reviewed radiation exposure in milliSieverts (mSv) for 82,214 participants from the SHAPE early detection program cohort who underwent CAC scoring. This occurred over a 2.5-year period (2012-2014) divided among 33 sites in 7 countries with four different types 64-MDCT scanners. The effective radiation dose was reported as mSv. Mean radiation dosing amongst all 82,214 participants was 1.03mSv, a median dose of 0.94mSv. The mean radiation dose ranged from 0.76 to 1.31mSv across the 33 sites involved with the SHAPE program cohort. Subgroup analysis by age, gender or body mass index (BMI) less than 30kg/m2 showed no variability. Radiation dose in patients with BMI > 30kg/m2 were significantly greater than other subgroups (µ = 1.96mSv, p < 0.001). The use of 64-MDCT scanners and protocols provide the effective radiation dose for CAC scoring, which is approximately 1mSv. This is consistently lower than previously reported for CAC scanning, regardless of scanner type, age or gender. In contrast, a greater BMI influenced mean radiation doses.

Dynamic contrast enhanced perfusion CT imaging: A diagnostic biomarker tool for survival prediction of tumour response to antiangiogenetic treatment in patients with advanced HCC lesions

PurposeTo investigate whether perfusion-CT (p-CT) imaging could depict the inhibition of tumor neoangiogenesis induced by Sorafenib in advanced hepatocellular carcinoma (HCC), and whether it could be useful in predicting survival during treatment. Materials and methodsNinety-eight p-CT examinations were performed among 29 cirrhotic patients, with advanced HCC, before and every 2 months after Sorafenib administration, on a 256-slice MDCT scanner. Perfusion parameters were considered and statistically compared, at baseline and follow-up, between non-progressor (complete response, stable disease or partial response) and progressor (progressive disease) group. Kaplan-Meier analyses estimated the time-to-survival in overall population, after stratifying patients according to mRECIST. ResultsThe group that responded to Sorafenib showed a significant reduction of values in HCC target lesions after anti-angiogenic therapy (p < 0.01), in comparison with progressor group that demonstrated an increase or no significant variation. When patients were stratified into mRECIST, higher survival rate was observed in the non-progressor group compared to the progressor (48.6% vs 28.6%), and statistically significant correlation (p=0.01) was found between percentage variation of perfusion parameters, from baseline to follow-up, and overall survival rate. ConclusionQuantitative analysis of perfusion parameters, represents prognostic indicators useful in assessment of response to anti-angiogenic therapy, allowing for optimization of individualized treatment.