MDCT Scanner Research Articles

Strain Analysis in Patients at High-Risk for COPD Using Four-Dimensional Dynamic-Ventilation CT.

PurposeTo quantitatively identify abnormal lung motion in chronic obstructive pulmonary disease (COPD) using strain analysis, and further clarify the potential differences of deformation in COPD with different severity of airflow limitation.Materials and MethodsTotally, 53 patients at high-risk for COPD were enrolled in this study. All CT examinations were performed on a 320-row MDCT scanner, and strain measurement based on dynamic-ventilation CT data was performed with a computational fluid dynamics analysis software (Micro Vec V3.6.2). The strain-related parameters derived from the whole expiration phase (PSmax-all, PSmean-all, Speedmax-all), the first 2s of expiration phase (PSmax2s, PSmean2s, Speedmax2s) were divided respectively by the changes in lung volume to adjust for the degree of expiration. Spearman rank correlation analysis was used to evaluate associations between the strain-related parameters and various spirometric parameters. Comparisons of the strain-related parameters between COPD and non-COPD patients, between GOLD I (mild airflow restriction) and GOLD II–IV (moderate to severe airflow restriction) were made using the Mann–Whitney U-test. Receiver-operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance of the strain-related parameters for COPD. P <0.05 was considered statistically significant.ResultsStrain-related parameters demonstrated positive correlations with spirometric parameters (ρ=0.275~0.687, P<0.05), suggesting that heterogeneity in lung motion was related to abnormal spirometric results. Strain-related parameters can quantitatively distinguish COPD from non-COPD patients with moderate diagnostic significance with the AUC values ranged from 0.821 to 0.894. Furthermore, parameters of the whole expiration phase (PSmax-all, Speedmax-all) demonstrated significant differences (P=0.005; P=0.04) between COPD patients with mild and moderate to severe airflow limitation.ConclusionStrain-related parameters derived from dynamic-ventilation CT data covering the whole lung associated with lung function changes in COPD, reflecting the severity of airflow limitation in some degree, even though its utility in severe COPD patients remains to be investigated.

Abstract MP25: Physical Activity And The Progression Of Coronary Artery Calcification

Introduction: High volume endurance physical activity (PA) has been shown to associate with increased clinically relevant coronary artery calcification (CAC) but not mortality. A key issue is whether active individuals with CAC have progression of atherosclerosis in the setting of sustained high levels of PA. Hypothesis: We hypothesized that changes in CAC are not related to corresponding changes in PA volume. Further, we hypothesized the rate of CAC progression to ≥100 Agatston units (AU) does not depend on baseline PA level. Methods: The study included 6,525 men and 2,056 women with ≥2 assessments of PA and CAC (EBT scans (1997-2007) or MDCT scans (2007-2019)). All individuals had at least one follow-up visit (mean=1.8). We used mixed linear regression to relate within-person changes in square-root CAC to changes in PA volume, controlling for between-person effects. We used interval-censored proportional hazards regression to test if progression to CAC≥100 AU was related to baseline PA level: ≥3000, 1500-2999, and &lt;1500 MET·minutes/week (MET·min/wk). Covariates included age, smoking, BMI, glucose, cholesterol, systolic blood pressure, and statin use. In addition, the longitudinal analysis was adjusted for time since baseline, while the time-to-CAC-threshold analysis was adjusted for baseline CAC. Results: Mean baseline age was 50 years in men/51 years in women. Mean time to first follow-up was 4.5 years in men/5.1 years in women. PA levels increased by 100 MET·min/wk in men but were stable in women. Cardiorespiratory fitness was stable between visits. Within person changes in CAC were not associated with changes in PA volume (Table). At baseline, 5285 men and 1948 women had CAC&lt;100 AU; at follow-up, 1127 men and 136 women progressed to CAC≥100 AU. Neither PA ≥3000 nor 1500-2999 MET·min/wk exhibited significant risk of CAC progression versus &lt;1500 MET·min/wk. Estimated hazard ratios were ≤1 for both men and women. Conclusions: These results show no apparent risk of increasing CAC with sustained PA in active individuals.

Abstract P072: Elevated Coronary Artery Calcification In Highly Active Men: Role Of Exercise Intensity Versus Duration

Introduction: While living a physically active lifestyle is associated with many health benefits, recent evidence suggests that high volume physical activity (PA) may contribute to coronary artery calcification (CAC). Whether exercise intensity or duration contributes more to CAC elevation is unknown. Hypothesis: Higher PA intensity, but not duration, predicts elevated CAC. Methods: We studied 25,801 apparently healthy men who completed a self-report PA questionnaire and underwent EBT or MDCT scans as part of a preventive physical examination. Participants were categorized into two CAC groups (≥100 or &lt;100 Agatston units (AU)) and three PA groups (≥3000, 1500 – 2999, and &lt;1500 MET-minutes/week (MET-min/wk)). An exploratory classification tree model identified maximum intensity of activity as the second most important predictor of CAC≥100 AU after age. As such, maximal intensity of activity ≥8 METs was entered as a predictor in subsequent logistic regression models that were adjusted for age, current smoking status, body mass index, glucose, total cholesterol, and systolic blood pressure. We also included categories of PA duration ≥5 or &lt;5 hours/week, the current PA Guidelines recommendation for increased performance. Results: The mean age was 52 years, and 6,075 men had CAC≥100 AU. Regardless of CAC category, the ≥3000 MET-min/wk group had more favorable glucose and lipid profiles compared to the &lt;1500 group. The average PA volume reported in the most highly active group (≥3000 MET-min/wk) was 4626 MET-min/wk with all participants reporting ≥5 hours of PA/week. In the fully adjusted model, maximum exercise intensity ≥8 METs was associated with lower risk of CAC≥100 AU (Relative risk (RR): 0.93, 95% Confidence interval (CI): 0.88 – 0.98, p = 0.004), while total duration of ≥5 hours/week trended in the opposite direction yet without significance (RR: 1.07, CI 95%: 0.98 – 1.17, p = 0.14). Prevalence of CAC≥100 AU was highest among those engaging only in activities &lt;8 METs and for a total duration ≥5 hours/week. Conversely, the lowest prevalence of CAC≥100 AU was found in the higher intensity, lower duration group (≥8 METs, &lt;5 hours/week). Jointly, maximum intensity ≥8 METs was associated with a lower risk of CAC≥100 AU (RR: 0.92, CI 95%: 0.88 – 0.97, p =0.003) only among those with a total duration &lt;5 hours/week. Conclusions: Exercise intensity ≥8 METs was associated with a lower likelihood of men patients presenting with clinically significant CAC while exercise duration of ≥5 hours/week trended in the opposite direction. These novel findings should be considered by clinicians when counseling highly active men with elevated CAC on their exercise prescriptions.

Evaluating the performance of unenhanced computed tomography in the diagnosis of pulmonary embolism

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary embolism (PE) is the third most common cardiovascular pathology after coronary artery disease and stroke with an incidence rate of 1 per 1000 individuals. Computed tomography pulmonary angiography (CTPA) as the gold standard examination in the detection of PE is contraindicated or unavailable in certain cases. Purpose The current study aimed to assess the accuracy of unenhanced CT in the diagnosis of PE. Methods A total of 195 consecutive participants with clinical suspicion for PE were enrolled in this prospective cohort study between October 2020 and March 2021. All patients were examined with a 16 slice multidetector (MD) CT scanner before performing the CTPA. Scans were independently reviewed by two expert radiologists who were blinded to patients’ clinical and laboratory history for imaging variables including presence and location of PE, hyper/hypodense intraluminal signs, pulmonary trunk enlargement, peripheral wedge-shaped opacity, and pleural effusion. First unenhanced CT scan and then CTPA were independently reviewed on a picture archiving and communications system workstation. Results There were 82 (42.1%) men and 113 (57.9%) women with the mean age ± standard deviation of 56 ±0.24 years. Based on CTPA results, 47 (24.1%) of 195 patients had PE of which 28 (59.5%) patients had central PE and 19 (40.5%) patients had peripheral PE. However, only 20 cases (42.5%) were detected with PE on MDCT scans consisting of 17 cases with (85%) central emboli and 3 cases with (15%) peripheral emboli. Given intraluminal clot density, 12 (60%) patients had hyperdense signs, 3 (15%) patients had hypodense signs, and 5 (25%) patients had mixed hyper-hypodense signs. There was a significant difference between central and peripheral embolies detected by MDCT. Intraluminal sign had the highest specificity and sensitivity (98.6%, 42.5%, AUC:0.734) followed by pulmonary trunk enlargement (84.4%, 36.1%, AUC: 0.603), peripheral wedge-shaped opacity (72.9%, 34%, AUC: 0.535), and pleural effusion (58.7%, 40.4%, AUC: 0.496). Our results did not show a remarkable difference in secondary findings from the MDCT scan including pulmonary trunk enlargement, peripheral wedge-shaped opacity, and pleural effusion concerning the presence of PE. Pleural effusion as the most common secondary finding in patients with PE was found in 31 (68.8%) of them. Conclusion Unenhanced MDCT has an acceptable performance to detect PE particularly central clots and should be considered as an alternative modality when CTPA is not available or indicated. Furthermore, the intraluminal sign is the main indicator of PE in MDCT images with the highest specificity and sensitivity. We recommend radiologists and other clinicians to be aware of intraluminal signs in case of unexpected PE.

Evaluation of Diagnostic Performance of MDCT Coronary Angiography in Comparison with Conventional Coronary Angiography

Abstract Background: Coronary artery disease is now becoming increasingly prevalent than before especially in younger age groups. We in the current study tried to evaluate the potential of 128 slice MDCT coronary angiography for the detection of stenotic coronary lesions by comparing the results of computed tomographic coronary angiography to a gold standard set by Conventional coronary angiography. Methods: A total of n=30 patients with clinically suspected Coronary artery disease. They were evaluated with 128 Slice CT Scanner (PHILIPS INGENUITY) and conventional coronary angiography. All patients were examined with a 128 slice MDCT scanner (Philips Ingenuity 128 slice Netherlands) using standard cardiac CT protocol. Gantry rotation time was 400 ms with a half sector acquisition protocol and multisector reconstruction permitting an effective temporal resolution between 50 and 200 ms depending on patient heart rate. Results: In the n=30 Patients included in the study with CCA, the n=450 coronary segments included in the study were found to contain a total number of n=138 stenoses among them non-significant stenoses. The accuracy of MDCT detection of coronary stenoses greater than 50% diameter of vessel lumen is about 94.78. When raising the threshold for stenosis from 50% to 70% of the vessel lumen, so that only hemodynamic relevant stenoses enter the evaluation, the sensitivity decreases from 88%. The MDCT detection in the patient group with heart rates below 60 beats per minute higher values for sensitivity 93% and specificity 97% were observed, compared to sensitivity 87% and specificity 93% of the patient group with heart rates above 60 beats per minute. Conclusion:The present study revealed that a high negative predictive value (98.08%)suggests that 128- Slice MDCT coronary angiography is a good screening modality for evaluation of patients with mild to intermediate-risk factors who might otherwise require invasive angiography.

Diagnostic capability and radiation safety of low dose CT cystography in acute post-traumatic urinary bladder injuries

Background: Genitourinary tract injuries occur in up to 5% of all traumas and at least 10% of abdominal traumas. Pelvic fractures are commonly found in patients with blunt trauma, and up to 40% of patients with bladder injuries are associated with at least one other intra-abdominal organ injury. Conventional cystography was the diagnostic modality for suspected bladder injury. Recently CT cystography is commonly used for evaluating bladder injury. For the risk of possible effects of radiation exposure associated with medical imaging procedures, the imaging centers apply the principles of ALARA. Aim of work: We aim to assess the diagnostic capability of low-dose CT cystography in the diagnosis and classification of acute post-traumatic bladder injury. Patients and methods: 44 patients with suspected post-traumatic UB injury were enrolled in this study. Non- and post-contrast CT scan was done using “160” MDCT scanner. Low and standard-dose techniques were applied, and the images were analyzed by two radiologists with at least 15 years of experience. Results: The study involved 44 patients. 20 patients scanned with low-dose CT while 24 patients scanned with the standard technique. Statistically, there was a significant difference between low and standard-dose groups regarding CTDI volume and radiation exposure (p=0.001) with a good diagnostic capability of low-dose CT. Conclusion: Low-dose CT cystography offers a good diagnostic capability of bladder injuries comparable to standard dose CT and may be recommended for the assessment of acute UB injuries.

A comprehensive Monte Carlo study of CT dose metrics proposed by the AAPM Reports 111 and 200.

A Monte Carlo (MC) modeling of single axial and helical CT scan modes has been developed to compute single and accumulated dose distributions. The radiation emission characteristics of an MDCT scanner has been modeled and used to evaluate the dose deposition in infinitely long head and body PMMA phantoms. The simulated accumulated dose distributions determined the approach to equilibrium function, H(L). From these curves, dose-related information was calculated for different head and body clinical protocols. The PENELOPE/penEasy package has been used to model the single axial and helical procedures and the radiation transport of photons and electrons in the phantoms. The bowtie filters, heel effect, focal-spot angle, and fan-beam geometry were incorporated. Head and body protocols with different pitch values were modeled for x-ray spectra corresponding to 80, 100, 120, and 140kV. The analytical formulation for the single dose distributions and experimental measurements of single and accumulated dose distributions were employed to validate the MC results. The experimental dose distributions were measured with OSLDs and a thimble ion chamber inserted into PMMA phantoms. Also, the experimental values of the along the center and peripheral axes of the CTDI phantom served to calibrate the simulated single and accumulated dose distributions. The match of the simulated dose distributions with the reference data supports the correct modeling of the heel effect and the radiation transport in the phantom material reflected in the tails of the dose distributions. The validation of the x-ray source model was done comparing the CTDI ratios between simulated, measured and CTDosimetry data. The average difference of these ratios for head and body protocols between the simulated and measured data was in the range of 13-17% and between simulated and CTDosimetry data varied 10-13%. The distributions of simulated doses and those measured with the thimble ion chamber are compatible within 3%. In this study, it was demonstrated that the efficiencies of the measurements in head phantoms with nT=20mm and 120kV are 80.6% and 87.8% at central and peripheral axes, respectively. In the body phantoms with =40mm and 120kV, the efficiencies are 56.5% and 86.2% at central and peripheral axes, respectively. In general terms, the clinical parameters such as pitch, beam intensity, and voltage affect the Deq values with the increase of the pitch decreasing the Deq and the beam intensity and the voltage increasing its value. The H(L) function does not change with the pitch values, but depends on the phantom axis (central or peripheral). The computation of the pitch-equilibrium dose product, , evidenced the limitations of the method to determine the dose delivered by a CT scanner. Therefore, quantities derived from the propagate this limitation. The developed MC model shows excellent compatibility with both measurements and literature quantities defined by AAPM Reports 111 and 200. These results demonstrate the robustness and versatility of the proposed modeling method.

CECT in Pulmonary Thrombolism

Introduction: Pulmonary embolism (PE) is the third most common acute heart disease after myocardial infarction and stroke and is a major public health problem. PE is a disease that has high morbidity and mortality, yet it is challenging to obtain a diagnosis.&#x0D; Objective: The study aims to assess the role of MDCT-PA in the diagnosis of pulmonary embolism, and it's associated conditions in suspected cases of pulmonary embolism.&#x0D; Materials and Methods: The study was conducted in the department of radiology in KRISHNA INSTITUTE OF MEDICAL SCIENCES DEEMED TO BE UNIVERSITY situated in KARAD equipped with a 16 slice MDCT scanner (EMOTION) manufactured by Siemens.&#x0D; Results: Through the study period of one and half year and have met the inclusion criteria, a total of 90 consecutive patients who presented with suspicion of PE were referred for MDCT-PA in the department of radio-diagnosis, Krishna Hospital, Karad. A review of all the cases was done, and the results were presented in the form of tables.&#x0D; Conclusion: Multidetector computed tomography pulmonary angiography can be used to confidently diagnose pulmonary embolism in which it is not contraindicated. MDCT-PA is the investigation of choice because it is a rapid, non-invasive study, highly sensitive and specific.

Percutaneous Angiographically Assisted Cryoablation of Renal Cell Carcinoma under the Control of Flat-Detector Computed Tomography: Capabilities and Potential Advantages of the Technique

Purpose: Percutaneous cryoablation (PCA) of renal cell carcinoma (RCC) stage T1a (≤4 cm) generally performed using MDCT with intravenous contrast material administration. Most interventional radiology departments are not equipped MDCT scanners and this is holding back widespread adoption of this technique into practical medicine. Flat-detector computed tomography (FDCT) is included in the standard equipment of modern angiographic systems, which makes it possible to combine the technologies of computed tomography with various technologies of intra-arterial contrasting and endovascular treatment. The purpose of the study was to assess the possibilities and potential advantages of using intraarterial contrasting during FDCT-controlled PCA of RCC T1a.Material and methods: Since 2017 angiographically assisted PCA under the FDCT control performed in 14 patients with RCC T1a. The procedure was performed in the X-ray operating room on an Artis Zee Floor angiographic unit with FDCT function and iGuide Needle Guidance and 3D/3D Fusion technologies (Siemens, Germany) using the SeedNet Gold system and IceEDGE 13 G, IceRod 17 G or IceSphere 17 G cryoprobes (Galil Medical, USA). At all stages of the procedure, FDCT-arteriography of the kidney (FDCT-A) performed according to the original technique: injection into the renal artery 12 ml of non-ionic contrast materials at a rate of 1 ml/s and performing scanning 5 s after the start of contrast materials injection.Results: The primary technical efficiency of FDCT-controlled PCA of RCC T1a was 92.9 %, the secondary — 100 %. Complications of grade 3 according to the CIRSE classification were identified in three patients (21.4 %), complications of grade 4, 5 and 6 not observed. The use of arterial access and the FDCT-A execution at different stages of PCA had the following advantages: 1) high-quality visualization of the tumor with minimal consumption of contrast materials; 2) simple and accurate positioning of cryoprobes using the iGuide Needle Guidance program; 3) estimation of the future ablative margin by fusion FDCT data about tumor with FDCT data about ice ball; 4) reliable diagnosis of bleeding after removal of cryoprobes with the possibility of immediate performing of endovascular hemostasis.Conclusion: Percutaneous angiographically assisted cryoablation under the FDCT control is an affordable, safe and effective technology for the treatment of RCC T1a, which has a number of potential advantages compared to performing procedures using MDCT control. Further research is advisable to study of this PCA technique with its subsequent possible introduction into the routine practice in Interventional Radiology departments of multidisciplinary oncological hospitals.

Association between myocardial wall thickness and left ventricular functional recovery after catheter ablation of atrial fibrillation in patients with reduced ejection fraction

Abstract Background Catheter ablation of atrial fibrillation (AFCA) is an effective treatment to develop left ventricular (LV) functional recovery. However, the degree of recovery differs between individuals due to the different extent of myocardial fibrosis and scarring. Purpose To examine whether pre-ablation LV wall thickness (WT) and its regional heterogeneity predict LV functional recovery after AFCA in patients with LV systolic dysfunction. Methods Of 3682 consecutive patients who underwent first-time AFCA between January 2012 and September 2020 in our institution, 174 (age, 63±10 years; male, 83%; ischemic cardiomyopathy, 14%) with a baseline LV ejection fraction (LVEF) of &amp;lt;40% were retrospectively evaluated. They were subjected to 256-slice MDCT scanning at baseline and 3 months after AFCA. Baseline WT was evaluated by 16-segment model. Mean and standard deviation (SD) of 16 regional WT were calculated in both end-systolic and end-diastolic phase. Results LVEF significantly improved from 30±7% to 57±17% (p&amp;lt;0.001) after AFCA. Increase in LVEF (delta-LVEF) was positively correlated with baseline end-diastolic WT (r=0.31, p&amp;lt;0.001) and negatively correlated with SD of end-systolic WT (r=−0.21, p=0.007). Independent of WT measurements, delta-LVEF was negatively correlated with LV end-diastolic volume (r=−0.42, p&amp;lt;0.001). We created a scoring system to predict the degree of wall motion recovery using the median value of the 3 variables; assigned 1 point each for end-diastolic WT &amp;gt;7.4mm, SD of end-systolic WT &amp;lt;1.61mm, and LV end-diastolic volume &amp;lt;125ml. The model successfully predicted improvement in LVEF after AFCA (0 point (N=13) vs. 1 point (N=72) vs. 2–3 point (N=89), 11±16% vs. 20±17% vs. 33±12%, p&amp;lt;0.001). Conclusion Myocardial WT and its regional heterogeneity as well as LV end-diastolic volume predicted functional recovery after AFCA in patients with reduced LVEF. Funding Acknowledgement Type of funding sources: None.

SleepTrip as a Tool to Create Analysis Pipelines for Investigations of Polysomnography in Clinical Populations

To investigate whether a newly-developed single-energy metal artifact reduction (SEMAR) algorithm applied to images acquired on a 320-MDCT volume scanner reduces image artifacts from dental metal.We inserted the lower right teeth covered with a dental metal alloy and crown in a skull phantom and performed single-volume scanning on a second-generation 320-MDCT scanner. A 12-mm diameter spherical lesion was placed either close to or far from the dental metal. The tube voltage and current were 120 kVp and 80 or 155 mA, respectively. Images were reconstructed with filtered back projection (FBP) or iterative reconstruction (IR), with or without SEMAR. We calculated the signal-to-artifact ratios (SAR) to quantify the visibility of the lesion. Two radiologists inspected 96 images (48 with lesion and 48 without) for the presence or absence of the lesion using a 5-point ordinal scale (1 = definitely absent to 5 = definitely present).On images reconstructed with FPB and IR with SEMAR, streak artifacts from the dental metal were reduced substantially compared to images without SEMAR. At 155 mA with the lesion near the dental metal, the SARs were better on FBP and IR images (FBP: 1.7 and 0.5 with and without SEMAR, respectively; IR: 1.6 and 0.9 with and without SEMAR, respectively). The observer visual scores improved with SEMAR (FBP: 4.2 and 3.2 with and without SEMAR, respectively; IR: 4.2 and 3.0).The SEMAR algorithm reduces dental metal artifacts and improves lesion detectability and image quality in patients with oral cavity lesions.

BRONCHIAL ARTERY EMBOLIZATION AS A THERAPEUTIC STRATEGY FOR MANAGEMENT OF MASSIVE HEMOPTYSIS

Background: Massive hemoptysis is an emergent and life-threatening condition with a high mortality rate. Bronchoscopy and MDCT scanning show significant contributing roles in delineating the etiology and the source of hemoptysis prior to bronchial artery arteriography.Aim of the work: To validate the role of the trans-catheter bronchial artery embolization in management of massive hemoptysis.Patients and Methods: Our study is a prospective cohort study that was held during the period between April 2017 and April 2019. The study included 20 patients who presented with massive hemoptysis refractory to supportive treatment measures with non-identifiable source of bleeding on fiber-optic bronchoscope. Patients were referred from chest department to angio unit.Results: Our findings are in accordance with the current literature supporting bronchial artery embolization as a safe and long-term non-invasive effective method of treatment for massive hemoptysis with a high initial rate of success. BAE may help to avoid surgery in patients who are not good surgical candidates. If hemoptysis recur in these patients, embolization can be safely performed with good response rate. If surgery is indicated, BAE can stabilize the patient prior to surgery.Conclusion: Advancements in angiographic equipment and technique continue to improve success rates, and with careful technique, it can be performed safely and with minimal risk. Embolization distal to the spinal artery may significantly decrease the number of complications and may allow a more thorough embolization.

Multi-detector computed tomography in traumatic abdominal lesions: value and radiation control

Background, The contextA prospective study was conducted involving 81 patients (mean age, 20.79 years) with abdominal trauma who underwent ultrasonography and post-contrast CT on MDCT scanner. The total DLP for each patient was reviewed, and the effective dose was calculated. Purpose of the study to: explore the role of MDCT in assessing traumatic abdominal lesions, demonstrate radiation dose delivered by MDCT, and describe specific CT technical features to minimize radiation.ResultsThe spleen was the most commonly injured organ (49.4%) followed by liver (39.5%) and kidney (24.7%). Pancreatic injury occurred in seven patients, whereas only two patients had intestinal injuries. One patient had adrenal injury. Minimal, mild and moderate free intra-peritoneal fluid collection was detected in 21 (25.9%), 47 (58%) and 10 (12.3%) patients, respectively. Only three (3.7%) patients had no collection. One patient had active uncontrolled bleeding and died. Radiation dose was below the detrimental level (calculated effective dose), with optimal image quality.ConclusionsMDCT is sensitive to all types of traumatic abdominal lesions. Not only in determining the injury, but also in its grading. MDCT has affected the treatment directions, spotting a focus on conservative treatment by raising the diagnostic confidence. FAST cannot be the sole imaging modality. The individual radiation risk is small but real. Advancements in medical imaging reduce radiation risk.

A deep learning approach to gold nanoparticle quantification in computed tomography.

Deep learning (DL) is used to classify, detect, and quantify gold nanoparticles (AuNPs) in a human-sized phantom with a clinical MDCT scanner. AuNPs were imaged at concentrations between 0.0274 and 200 mgAu/mL in a 33cm phantom. 1mm-thick CT image slices were acquired at 120 kVp with a CTDIvol of 23.6mGy. A convolutional neural network (CNN) was trained on 544 images to classify 17 different tissue types and AuNP concentrations. A second set of 544 images was then used for testing. AuNPs were classified with 95% accuracy at 0.1095 mgAu/mL and 97% accuracy at 0.2189 mgAu/mL. Both these concentrations are lower than what humans can visually perceive (0.3-1.4 mgAu/mL). AuNP concentrations were also classified with 95% accuracy at 150 and 200 mgAu/mL. These high concentrations result in CT numbers that are at or above the 12-bit limit for CT's dynamic range where extended Hounsfield scales are otherwise required for measuring differences in contrast. We have shown that DL can be used to detect AuNPs at concentrations lower than what humans can visually perceive and can also quantify very high AuNP concentrations that exceed the typical 12-bit dynamic range of clinical MDCT scanners. This second finding is possible due to inhomogeneous AuNP distributions and characteristic streak artifacts. It may even be possible to extend this approach beyond AuNP imaging in CT for quantifying high density objects without extended Hounsfield scales.

Assessment of blunt abdominal injury using computed tomography scan: A cross-sectional study

Background and Aim: Assessment of hemodynamic stability is the most important initial concern in the evaluation of a patient with blunt abdominal trauma. Computed tomography is also the modality of choice for diagnosing injuries to the diaphragm, which may result in major morbidity and mortality if undetected and may not present until many years after the event. Hence, the present study was conducted to study computed tomography evaluation of blunt abdominal injury.Material and Methods: abdomen CT scan reports of 80 patients with BAT, who were stable enough to undergo radiological investigation were used for this study. 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 analyzed for their role in guiding the therapeutic options, whether conservative or surgical.Results: The mean age of patients was 42.05 years. Number of male patients was 55 and number of female patients was 25. It was observed that OIS grade II patients were 14, OIS grade III patients were 24, OIS grade IV patients were 7 and OIS grade V patients were 5. The highest proportions of conservatively managed patients were seen in OIS grade II patients. However, highest proportion of operated patients was seen in OIS grade III patients. Conclusion: 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.

Efficiency Assessment of Multidetector-Row Computed Tomographic Angiography Using Reconstruction with Locoregional Perforator Flaps.

Background: Reconstruction with the use of perforator flaps makes it possible to make the skin surface resistant to the influence of mechanical factors and as similar to the lost skin cover as possible. However, while planning any flap, along with the design of the required shape and size, its blood supply should be taken into account to ensure optimal viability. Therefore, the task to precisely determine the topographic-anatomical relationships suitable for the formation of a pedicle of perforators is still relevant. The aim of this study was to increase the efficiency of surgical reconstruction of wound defects by transposition of locoregional perforator flaps. Methods: The authors conducted a retrospective analysis of 72 cases of reconstruction by means of locoregional perforator flaps with vascular pedicle detachment to determine the efficiency of preoperative diagnostic preparation with the help of multidetector-row computed tomographic angiography (MDCT) in the process of reconstruction. Thirty-seven individual cases of surgical interventions were chosen using a case-controlled study from the study group when MDCT with angiography was used for preoperative planning of perforator flaps, as well as 35 control cases similar in terms of important predictive peculiarities with the reconstruction at the same level of difficulty. The patient groups were precisely matched by gender (P = .950), age (P = .804), flap area (P = .192), and type of reconstruction that was performed. Results: In all cases, the location of the perforator with a diameter greater than 1.0 mm was marked. All perforators determined during MDCT scanning were faultlessly localized intraoperatively. The distance between the intraoperative position of the perforator and the position obtained in the result of the examination did not exceed 1 cm. There was no need to change the planned design of the flap intraoperatively. In all cases where MDCT was performed, the duration of the surgical procedure varied from 60 to 150 minutes (average: 120.77 [18.90] minutes) and was reduced by 49.40 minutes (95% CI: 39.17-59.63) compared with the patients who did not undergo preoperative visualization of perforators where the average duration of the operation was 170.17 (19.19) minutes (from 140 to 220 minutes). Among the patients examined by MDCT, surgical complications were noted in 5 cases (13.51%) compared to 14 cases (40.00%) in the control group. Conclusions: The preoperative MDCT for the locoregional perforator flap reconstruction makes it possible to increase the efficiency of patient treatment given the reduction in surgery duration by 49.40 minutes (95% CI: 39.17-59.63) on average and the reduction in the level of postsurgery complications from 40% to 13.5% compared with the group of patients in whom presurgical visualization was not performed (P = .031).

Ultra-low-dose lung multidetector computed tomography in children – Approaching 0.2 millisievert

PurposeTo compare objective and subjective parameters in image quality and radiation dose of two MDCTs (helical 64 detector CT vs. axial 256 detector CT) in paediatric lung CT. MethodsRadiation dose and image quality were compared between non-enhanced lung CT from a helical 64-slice multidetector CT (MDCT 1) and a 256-slice scanner (MDCT 2) with axial wide-cone acquisition and using deep learning image reconstruction. In 23 size-matched paediatric studies (age 2–18 years) from each scanner, the radiation exposure, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), image sharpness and delineation of small airways were assessed. Subjective image quality was rated by 6 paediatric radiologists. ResultsWhile MDCT 2 provided higher SNR and CNR, subjective image quality was not significantly different between studies from both scanners. Radiation exposure was lower in studies from MDCT 2 (CTDIvol 0.26 ± 0.14 mGy, effective dose 0.23 ± 0.11 mSv) than from MDCT 1 (CTDIvol 0.96 ± 0.52 mGy, effective dose 1.13 ± 0.58 mSv), p < 0.001. Despite lower radiation dose for the scout images, the relative scout-scan-ratio increased from 2.64 ± 1.42 % in MDCT 1 to 6.60 ± 5.03 % in MDCT 2 (p = 0.001). ConclusionsBy using latest scanner technology effective radiation dose can be reduced to 0.1−0.3 mSv for lung CT in children without compromising image quality. Scout image dose increasingly accounts for substantial portions of the total scan dose and needs to be optimized. In children CT should be performed on state-of-the-art MDCT scanners with size-adapted exposure protocols and iterative reconstruction.

Adrenal incidentalomas: imaging challenges\u2014role of MDCT scan versus MRI in evaluating adrenal incidentalomas

BackgroundThe term adrenal incidentaloma (AI), by definition, is an adrenal mass that is unexpectedly detected through an imaging procedure performed for reasons unrelated to adrenal dysfunction or suspected dysfunction. Despite their frequent appearance, the challenge remains in recognizing and treating the small percentage of AI that poses a significant risk, either because of their hormonal activity or because of their malignant histology. The aim of this study is to study the role of MRI, specifically chemical shift imaging (CSI), against various MDCT scans (non-enhanced, enhanced, and delayed) in the characterization of incidentally discovered adrenal masses to offer a way for the patients to avoid unnecessary time and money-wasting imaging modalities used to reach a diagnosis of their incidentally discovered adrenal lesions. We examined a total number of 20 patients with total of 22 adrenal lesions. The mean age was 51.1 ± 15.27.ResultsIn our study, we found that among CT parameters, APW and RPW showed the highest sensitivity and specificity for detection of lipid-rich adenomas. CSI has also proven to be the best MR technique. However, there is no statistically significant difference in the diagnostic capability of CSI versus the CT washout technique. Both modalities could be conducted, according to specific patient preferences and/or limitations, with comparable highly accurate outcomes.ConclusionThis study demonstrates that a similar diagnostic outcome is obtained from contrast-enhanced CT (CECT) and MRI with CSI of adrenal lesions.

The combined application of the contrast-to-noise index and 80 kVp for cardiac CTA scanning before atrial fibrillation ablation reduces radiation dose exposure

IntroductionTo compare the radiation dose, diagnostic accuracy, and the resultant ablation procedures using 80 and 120-kVp cardiac computed tomography angiography (CCTA) protocols with the same contrast-to-noise ratio in patients scheduled for atrial fibrillation (AF) ablation. MethodsThis retrospective study was performed following institutional review board approval. We divided 140 consecutive patients who had undergone CCTA using a 64-MDCT scanner into two equal groups. Standard deviation (SD) of the CT number was set at 25 Hounsfield units (HU) for the 120-kVp protocol. To facilitate a reduction in radiation dose it was set at 40 HU for the 80 kVp protocol. We compared the two protocols with respect to the radiation dose, the diagnostic accuracy for detecting left atrial appendage (LAA) thrombi, matching for surface registration, and the resultant ablation procedures. ResultsAt 120 kVp, the dose length product (DLP) was 2.2 times that at 80 kVp (1269.0 vs 559.0 mGy cm, p < 0.01). The diagnostic accuracy for thrombus detection was 100% using both protocols. There was no difference between the two protocols with respect to matching for surface registration. The protocols did not differ with respect to the subsequent time required for the ablation procedures and the ablation fluoroscopy time, and the radiation dose (p = 0.54, 0.33, and 0.32, respectively). ConclusionFor the same CNR, the DLP at 80 kVp (559.0 mGy cm) was 56% of that delivered at 120 kVp (1269.0 mGy cm). There was no reduction in diagnostic accuracy. Implications for practiceMaintaining CNR allows for a reduction in the radiation dose without reducing the image quality.

Abdominal Ultrasound Compared to MDCT in Assessment of Colorectal Cancer

Background and Aim: Colorectal cancer is the third most common cancer and the fourth most frequent cause of cancer deaths worldwide. The aim of this study to compare the diagnostic performance of abdominal ultrasound and multidetector CT in detection of colorectal cancer. Methods: this study included fifty patients were presented to surgical department of Mit Ghamr oncology center. All patients were examined on MDCT to show presence of the cancer. then examined by abdominal ultrasound to evaluate ability of ultrasound to detect the cancer. Results: fifty patients were included (28 men and 22 women) had a mean age of 47.5years (range 28-70years). Our study results suggested that abdominal ultrasound had sensitivity and specificity in diagnosis of cancer colon were 82.4% and 87.5 % respectively. The accuracy of US was 84%. For MDCT, sensitivity and specificity of cancer colon were 100% and 93.8 respectively. The accuracy of MDCT was 98%. Conclusion: ultrasonography is a useful initial screening tool for colorectal cancer in patients presenting with abdominal distension. Compared with MDCT scanning and other modalities. Ultrasonography is easily available; does not involve radiation, bowel preparation, or sedation; carries no risk of colonic perforation; and is less expensive. Further studies to confirm the usefulness of ultrasonography for diagnosis of colorectal cancer are warranted. CT is valuable in preoperative assessment and staging of colorectal cancer as well as in postoperative surveillance for recurrence. Rapid advances in technology will likely continue to improve the accuracy and usefulness of CT.