128-slice Dual-source Computed Tomography Scanner Research Articles

Association between Lipoprotein Subfractions, Hemostatic Potentials, and Coronary Atherosclerosis.

Background Dyslipidemias are associated with atherosclerotic plaque formation and a prothrombotic state, thus increasing the risk of both atherosclerotic vascular disease and atherothrombotic adverse events. We sought to explore the association between lipoprotein subfractions, overall hemostasis, and coronary calcifications in individuals at intermediate cardiovascular risk. Methods Consecutive statin-naive individuals at intermediate cardiovascular risk referred for coronary artery calcium score (CACS) scanning were included. CACS was assessed using a 128-slice dual-source CT scanner. Traditional lipid profile, high-density lipoprotein (HDL) subfractions 2 and 3, and small dense low-density lipoproteins (sdLDL) were measured with commercially available assays. Overall hemostatic (OHP) and coagulation potentials (OCP) were measured spectrophotometrically, using fibrin aggregation curves after exposure to thrombin and recombinant tissue-type plasminogen activator, respectively. Overall fibrinolytic potential (OFP) was calculated as a difference between the two areas under curves. Results We included 160 patients (median age 63 (interquartile range (IQR), 56-71 years, 52% women, and median CACS 8, IQR 0-173 Agatston units). HDL3 levels—but not sdLDL or hemostatic potentials—were significantly associated with CACS zero, even after adjusting for age, sex, arterial hypertension, dyslipidemia, diabetes, and smoking history (OR 0.980 (0.962-0.999), p = 0.034). HDL3 was also significantly associated with OCP (r = −0.232, p adjusted for age and sex 0.037). Conclusions In patients at intermediate cardiovascular risk, HDL3 is associated with both subclinical atherosclerosis and overall coagulation. Our findings are in line with studies reporting on an inverse relationship between HDL3 and atherosclerosis and provide one possible mechanistic explanation for the association between novel lipid biomarkers and coagulation derangements.

Diagnostic Accuracy of 128-Slice Dual Source CT Coronary Angiography with Invasive Catheter Coronary Angiography in a Tertiary Care Teaching Hospital

Background: Coronary artery disease (CAD) morbidity and mortality increasing day by day in India as well as worldwide. Coronary arteries visualization by using invasive catheterization angiography is still using as a front-line diagnostic tool to evaluate the patients with CAD. 128 slice dual source CT improves the cardiac imaging such as high scanning speed, good temporal resolution and low radiation dose. Objective: To assess the diagnostic accuracy of 128-slice dual source CT cardiac angiography with conventional catheter angiography to find common arteries involved in CAD. Methods: This is a prospective, comparative, cross sectional study conducted at cardiology OPD. Patients with complaint of chest pain and suspected CAD were evaluated by CT and conventional coronary angiography and results were compared. Serum creatinine and ECG status were analyzed before the angiography. SIEMENS 128-slice Dual Source Flash Definition CT Scanner was used as a CT coronary angiography. Severity distribution of coronary artery disease, artery wise distribution of non-significant, significant lesions and coronary artery dominance pattern were analyzed and compared. Results: A total of 70 suspected CAD patients were selected and analyzed. American Heart Association (AHA) model of 17-segment was used to assess the coronary arteries. Normal angiograms reported in 15.71% patients and 58.57% had significant disease. A total of 356 lesions were identified from 690 out of 720 segments. Right coronary artery (RCA) is the most common location of significant lesions which contributes 33.5% (n=55/164). Coronary circulation of right-sided dominance was most commonly reported (70.0%). CT angiography showed 96.13% of an overall sensitivity, 96.28% specificity, 89.72% positive predictive value and 98.49% negative predictive value. Conclusion: 128-slice dual source CT scanner has showed high accuracy and act as non-invasive assessment of coronary arteries in patients with CAD Keywords: Cardiac angiography, Catheter coronary angiography, CT coronary angiography, 128-slice MDCT, Conventional angiography

ROLE OF 128-SLICE, DUAL-SOURCE CT CORONARY ANGIOGRAPHY AS A NOVEL IMAGING TECHNIQUE IN ASSESSMENT OF IN-STENT RESTENOSIS

Background: Over the past 35 years, catheter-based intervention has become the dominant form of coronary revascularization. Percutaneous coronary interventions are increasingly performed. The most important advance in the field of percutaneous coronary interventions was the introduction of coronary stent implantation in the 1990s, which led to reductions in incidence of restenosis. The use of multi–slice CT is gaining increasing acceptance for noninvasive cardiac imaging. Recent years with the new emerging machines have demonstrated successful application of multi–slice CT angiography for the noninvasive assessment of coronary artery disease and the evaluation of coronary artery stents.Aim of the Work: To evaluate the role of 128-slice, dual-source CT coronary angiography as a novel technique in assessment of coronary artery in-stent restenosis. Patients and Methods: This study included forty patients withprior coronary artery stent implantation. The mean age of the included patients was 58 with an age range between 40 and 73 years. A total of 42 coronary artery stents deployed within 40 patients were included in this study; and assessed by MSCT angiography and they underwent invasive coronary angiography as a gold standard for evaluation of the coronary artery stents. Results: In an overall view, MSCT angiography compared to the invasive coronary angiography as a gold standard technique gave us a sensitivity of 100%, a specificity of about 83.8 %, an accuracy of about 87.1%, positive predective value (PPV) is 61.5% and negative predective value (NPV) is 100% in the assessment of the patency ofthe coronary artery stents, taking into consideration proper standard CT angiography techniques in all cases.Conclusion: Our study helps to identify factors that influence the assessability of coronary artery stents by 128-slice dual source CT scanner, namely, stent type and diameter. It shows that under certain conditions, the detection of in-stent restenosis might be possible with an accuracy that could permit clinical applications, but the nonassessable stents do not allow the use of MSCT coronary angiography in unselected patients with implanted stents in coronary arteries. So that MSCT angiography as a noninvasive technique can be used for assessment of in-stent restenosis but patients must becarefully selected.

Ultra-low dose one-step CT angiography for coronary, carotid and cerebral arteries using 128-slice dual-source CT: A feasibility study.

Atherosclerotic diseases are systemic and patient outcomes depend on comprehensive imaging evaluation. Computed tomography angiography (CTA) is a powerful tool used to assess atherosclerosis. However, the scanning protocol is designed for cardiovascular and cerebrovascular imaging, which require considerations into the radiation dose, contrast agent and image quality. The purpose of the present study was to evaluate ultra-low dose one-step CTA for coronary, carotid and cerebral arteries with a low concentration contrast agent. A total of 78 patients were enrolled and randomly divided into two groups: Group A (n=38) and B (n=40). High-pitch CTA for coronary, carotid and cerebral arteries with a tube voltage of 70 or 80 kVp and 40 ml contrast agent (270 mgI/ml) was performed by a 128-slice dual-source CT scanner for group A. Standard high-pitch CTA with a tube voltage of 100 kVp and 60 ml contrast agent (370 mgI/ml) was conducted for group B. The image quality, radiation dose and amount of contrast agent in group A were evaluated and compared with group B. The dose length product for groups A and B was 62.95±21.54 vs. 160.15±15.13 mGy cm, respectively (t=−23.157, P<0.001). The mean total iodine content was 10.8±0 mg for group A and 22.2±0 mg for group B. In total, 99.4% of the arterial segments could be assessed for the two groups (χ2=0.267, P=0.606). The results revealed that ultra-low dose one-step high-pitch CTA can provide assessable image quality, and minimize the radiation dose and contrast agent.

In Vivo Analysis of Urinary Stones With Dual-Energy Computed Tomography.

Formation mechanisms and treatment of the urinary stones are different, depending on their chemical structure. Therefore, determining the stone type plays a key role in planning treatment and preventive measures. Computed tomography (CT), with the use of dual-energy technology in recent years, has made it possible to do in vivo analysis of urinary stones. In this study, we aimed to evaluate the diagnostic efficacy of dual-energy CT (DECT) and compare its results with in vitro analysis, which is accepted as a gold standard for analysis of urinary stones. The DECT examinations were performed on 373 patients using 128-slice dual-source CT scanner. Analysis of attenuation ratios in the high and low kilovoltage peak values of the stone was performed at workstation, and stones were classified as hydroxyapatite, calcium oxalate, cystine, and uric acid. On follow-up, the stone was obtained in 35 patients as a result of surgery or passed spontaneously. The DECT analysis and in vitro analysis results were compared and statistically evaluated. In all patients, 136 hydroxyapatite, 160 calcium oxalate, 57 uric acid, and 20 cystine stones were detected with DECT. In vitro analyses of the stones were performed in 35 patients, and 8 hydroxyapatite, 18 calcium oxalate, 6 uric acid, and 3 cystine stones were revealed. When DECT analysis results were compared with in vitro analysis results, stone types were detected correctly in 32 (91.4%) patients and incorrectly in 3 (8.6%) patients. Especially all uric acid and cystine stones were correctly detected with DECT. With advanced postprocess analysis methods, DECT is able to analyze urinary stones. The DECT is found superior especially in detecting uric acid and cystine stones. Its success in detecting hydroxyapatite and calcium oxalate stones is also high. When in vivo analyses of the stones are performed with DECT, it will be possible to make a contribution to the personalization and optimization of the treatment.

Photon Counting Computed Tomography With Dedicated Sharp Convolution Kernels: Tapping the Potential of a New Technology for Stent Imaging.

The aims of this study were to assess the value of a dedicated sharp convolution kernel for photon counting detector (PCD) computed tomography (CT) for coronary stent imaging and to evaluate to which extent iterative reconstructions can compensate for potential increases in image noise. For this in vitro study, a phantom simulating coronary artery stenting was prepared. Eighteen different coronary stents were expanded in plastic tubes of 3 mm diameter. Tubes were filled with diluted contrast agent, sealed, and immersed in oil calibrated to an attenuation of -100 HU simulating epicardial fat. The phantom was scanned in a modified second generation 128-slice dual-source CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Erlangen, Germany) equipped with both a conventional energy integrating detector and PCD. Image data were acquired using the PCD part of the scanner with 48 × 0.25 mm slices, a tube voltage of 100 kVp, and tube current-time product of 100 mAs. Images were reconstructed using a conventional convolution kernel for stent imaging with filtered back-projection (B46) and with sinogram-affirmed iterative reconstruction (SAFIRE) at level 3 (I463). For comparison, a dedicated sharp convolution kernel with filtered back-projection (D70) and SAFIRE level 3 (Q703) and level 5 (Q705) was used. The D70 and Q70 kernels were specifically designed for coronary stent imaging with PCD CT by optimizing the image modulation transfer function and the separation of contrast edges. Two independent, blinded readers evaluated subjective image quality (Likert scale 0-3, where 3 = excellent), in-stent diameter difference, in-stent attenuation difference, mathematically defined image sharpness, and noise of each reconstruction. Interreader reliability was calculated using Goodman and Kruskal's γ and intraclass correlation coefficients (ICCs). Differences in image quality were evaluated using a Wilcoxon signed-rank test. Differences in in-stent diameter difference, in-stent attenuation difference, image sharpness, and image noise were tested using a paired-sample t test corrected for multiple comparisons. Interreader and intrareader reliability were excellent (γ = 0.953, ICCs = 0.891-0.999, and γ = 0.996, ICCs = 0.918-0.999, respectively). Reconstructions using the dedicated sharp convolution kernel yielded significantly better results regarding image quality (B46: 0.4 ± 0.5 vs D70: 2.9 ± 0.3; P < 0.001), in-stent diameter difference (1.5 ± 0.3 vs 1.0 ± 0.3 mm; P < 0.001), and image sharpness (728 ± 246 vs 2069 ± 411 CT numbers/voxel; P < 0.001). Regarding in-stent attenuation difference, no significant difference was observed between the 2 kernels (151 ± 76 vs 158 ± 92 CT numbers; P = 0.627). Noise was significantly higher in all sharp convolution kernel images but was reduced by 41% and 59% by applying SAFIRE levels 3 and 5, respectively (B46: 16 ± 1, D70: 111 ± 3, Q703: 65 ± 2, Q705: 46 ± 2 CT numbers; P < 0.001 for all comparisons). A dedicated sharp convolution kernel for PCD CT imaging of coronary stents yields superior qualitative and quantitative image characteristics compared with conventional reconstruction kernels. Resulting higher noise levels in sharp kernel PCD imaging can be partially compensated with iterative image reconstruction techniques.

Third-generation dual-source 70-kVp chest CT angiography with advanced iterative reconstruction in young children: image quality and radiation dose reduction.

Many technical updates have been made in multi-detector CT. To evaluate image quality and radiation dose of high-pitch second- and third-generation dual-source chest CT angiography and to assess the effects of different levels of advanced modeled iterative reconstruction (ADMIRE) in newborns and children. Chest CT angiography (70 kVp) was performed in 42 children (age 158 ± 267 days, range 1-1,194 days). We evaluated subjective and objective image quality, and radiation dose with filtered back projection (FBP) and different strength levels of ADMIRE. For comparison were 42 matched controls examined with a second-generation 128-slice dual-source CT-scanner (80 kVp). ADMIRE demonstrated improved objective and subjective image quality (P < .01). Mean signal/noise, contrast/noise and subjective image quality were 11.9, 10.0 and 1.9, respectively, for the 80 kVp mode and 11.2, 10.0 and 1.9 for the 70 kVp mode. With ADMIRE, the corresponding values for the 70 kVp mode were 13.7, 12.1 and 1.4 at strength level 2 and 17.6, 15.6 and 1.2 at strength level 4. Mean CTDIvol, DLP and effective dose were significantly lower with the 70-kVp mode (0.31 mGy, 5.33 mGy*cm, 0.36 mSv) compared to the 80-kVp mode (0.46 mGy, 9.17 mGy*cm, 0.62 mSv; P < .01). The third-generation dual-source CT at 70 kVp provided good objective and subjective image quality at lower radiation exposure. ADMIRE improved objective and subjective image quality.

128-slice dual-source CT coronary angiography with prospectively electrocardiography-triggered high-pitch spiral mode: radiation dose, image quality, and diagnostic acceptability.

Dual-source computed tomography (CT) enables CT coronary angiography (CTCA) with a prospectively electrocardiography (ECG)-triggered high-pitch spiral (HPS) mode. To evaluate the radiation dose, image quality, and diagnostic acceptability of the HPS mode in CTCA and to compare HPS with the step-and-shoot (SAS) and low-pitch spiral (LPS) modes. One hundred and thirty-eight patients who underwent CTCA with a 128-slice dual-source CT scanner were retrospectively included in this study. Seventeen patients (average heart rate of ≤65 beats per minute [bpm] prior to acquisition) were evaluated in the HPS mode, 88 (average heart rate of >65 and ≤80 bpm prior to acquisition) in the SAS mode, and 33 (average heart rate of >80 bpm prior to acquisition or patients with an unstable heart rhythm) in the LPS mode. Radiation dose and image noise were recorded for each patient. Diagnostic acceptability was graded using a four-point scale (1, unacceptable; 2, suboptimal; 3, acceptable; 4, fully acceptable). The effective dose in the HPS mode was 1.5 ± 0.2 mSv, which was lower than that in SAS (8.9 ± 2.7 mSv) and LPS (21.5 ± 4.3 mSv) modes. There were no significant differences in the image noise levels in the descending aorta and left atrium. The average per-patient diagnostic acceptability was 3.2, 3.6, and 3.7 in HPS, SAS, and LPS modes, respectively. The radiation dose is lower with HPS than with other modes, and the HPS mode-acquired images of patients with heart rates of ≤65 bpm are nearly acceptable for diagnostic image interpretation.

Normal range and regional heterogeneity of myocardial perfusion in healthy human myocardium: assessment on dynamic perfusion CT using 128-slice dual-source CT

Information about myocardial perfusion in healthy hearts is essential for evaluating patients with ischemic heart disease. The purpose of this study was to determine the range and regional variability of myocardial perfusion in normal volunteers on dynamic perfusion computed tomography (CT). Myocardial perfusion was assessed in 19 healthy volunteers (age 33-60 years; 11 men) at rest and during adenosine-induced hyperemia using a 128-slice dual-source CT scanner. Data were quantified as cc/cc/min for the transmural myocardium based on a 17-segment American Heart Association model. Mean myocardial blood flows (MBF) were 1.73 ± 0.33 cc/cc/min during adenosine-induced hyperemia, 0.83 ± 0.21 cc/cc/min at rest, and perfusion reserve was 2.20 ± 0.53. Regional variability was 17 ± 5% for hyperemic perfusion, 18 ± 7% for resting, and 21 ± 6 % for perfusion reserve. Although statistically insignificant, perfusion in the septum was lower at rest and during hyperemia than in other regions. Women tended to have lower perfusion during hyperemia (1.65 ± 0.40 vs. 1.79 ± 0.28 cc/cc/min, P = 0.40), and higher perfusion at rest than men (0.91 ± 0.27 vs. 0.77 ± 0.15 cc/cc/min, P = 0.23), resulting in lower perfusion reserve (1.86 ± 0.31 vs. 2.45 ± 0.53, P = 0.11). This small cohort of healthy volunteers study reveals normal myocardial perfusion parameter on dynamic perfusion CT as follows: mean MBF is 1.73 ± 0.33 cc/cc/min during hyperemia, 0.83 ± 0.21 cc/cc/min at rest, and perfusion reserve is 2.20 ± 0.53. And the study also demonstrates considerable regional heterogeneity of the myocardial perfusion.

Dual energy CT angiography of the carotid arteries: Quality, bone subtraction, and radiation dosage using tube voltage 80/140 kV versus 100/140 kV

ObjectiveTo study the differences in vascular image quality, bone subtraction, and dose of radiation of dual energy CT angiography of the supraaortic trunks using different tube voltages. Materials and methodsWe reviewed the CT angiograms of the supraaortic trunks in 46 patients acquired with a 128-slice dual source CT scanner using two voltage protocols (80/140kV and 100/140kV). The “head bone removal” tool was used for postprocessing. We divided the arteries into 15 segments. In each segment, we evaluated the image quality of the vessels and the effectiveness of bone removal in multiplanar reconstructions (MPR) and in maximum intensity projections (MIP) with each protocol, analyzing the trabecular and cortical bones separately. We also evaluated the dose of radiation received. ResultsOf the 46 patients, 13 were studied using 80/140kV and 33 with 100/140kV. There were no significant differences between the two groups in age or sex. Image quality in four segments was better in the group examined with 100/140kV. Cortical bone removal in MPR and MIP and trabecular bone removal in MIP were also better in the group examined with 100/140kV. The dose of radiation received was significantly higher in the group examined with 100/140kV (1.16mSv with 80/140kV vs 1.59mSv with 100/140kV). ConclusionUsing 100/140kV increases the dose of radiation but improves the quality of the study of arterial segments and bone subtraction.

Comparison of 128-Slice Dual Source CT Coronary Angiography with Invasive Coronary Angiography.

Coronary artery disease (CAD) is one of the leading cause of the morbidity and mortality in India as well as worldwide and last decade has seen a steep rise in incidence of CAD in India. Direct visualization of the coronary arteries by invasive catheterization still represents the cornerstone of the evaluation of CAD. Cardiac imaging is a challenge of 21 (st) century and is being answered by 128 slice dual source CT as it has good temporal resolution, high scanning speed as well as low radiation dose. To assess the diagnostic accuracy of 128-slice dual source CT Cardiac Angiography in comparison with Conventional Catheter Cardiac Angiography. Forty patients attending the cardiology OPD with complaint of chest pain and suspected of having CAD were evaluated by CT coronary angiography and conventional invasive Catheter coronary angiography and the results were compared. All patients were checked for serum creatinine and ECG before the angiography. Computed Tomography (CT) coronary angiography was done using SIEMENS 128-slice Dual Source Flash Definition CT Scanner under either Retrospective or Prospective mode depending on the heart rate of the patient. Oral/IV beta-blocker were used whenever required. Coronary arteries were assessed as per 17- segment AHA model. A total of 600/ 609 segments were evaluable in 40 suspected patients on CT coronary angiography, of which 21 were false positives and 8 were false negatives with specificity of 95.12% and sensitivity and positive predictive value of 95.26% & 88.46% respectively. Non-invasive assessment of CAD is now possible with high accuracy on 128-slice dual source CT scanner.

Performance evaluation of CT automatic exposure control on fast dual spiral scan

The performance of individual computed tomography automatic exposure control (CT-AEC) is very important for radiation dose reduction and image quality equalization in CT examinations. The purpose of this study was to evaluate the performance of CT-AEC in conventional pitch mode (Normal spiral) and fast dual spiral scan (Flash spiral) in a 128-slice dual-source CT scanner. To evaluate the response properties of CT-AEC in the 128-slice DSCT scanner, a chest phantom was placed on the patient table and was fixed at the center of the field of view (FOV). The phantom scan was performed using Normal spiral and Flash spiral scanning. We measured the effective tube current time product (Eff. mAs) of simulated organs in the chest phantom along the longitudinal (z) direction, and the dose dependence (distribution) of in-plane locations for the respective scan modes was also evaluated by using a 100-mm-long pencil-type ionization chamber. The dose length product (DLP) was evaluated using the value displayed on the console after scanning. It was revealed that the response properties of CT-AEC in Normal spiral scanning depend on the respective pitches and Flash spiral scanning is independent of the respective pitches. In-plane radiation dose of Flash spiral was lower than that of Normal spiral. The DLP values showed a difference of approximately 1.7 times at the maximum. The results of our experiments provide information for adjustments for appropriate scanning parameters using CT-AEC in a 128-slice DSCT scanner.

Adenosine-stress low-dose single-scan CT myocardial perfusion imaging using a 128-slice dual-source CT: a comparison with fractional flow reserve

Coronary CT angiography (CCTA) allows accurate evaluation of coronary artery stenosis but has limitations in information on hemodynamic significance of stenotic lesions. To determine the feasibility of adenosine-stress low-dose single-scan CT myocardial perfusion imaging (MPI) using a 128-slice dual-source CT scanner for the diagnosis of hemodynamically significant coronary artery stenosis as defined by fractional flow reserve (FFR). This study was proved by the Institutional Review Board and informed consent was obtained from the patients before enrollment in the study. Ninety-seven patients with chest pain and low-to-intermediate pretest probability of coronary artery disease were prospectively enrolled. Adenosine-stress CCTA using ECG-correlated maximum tube current modulation (Mindose(®)) with 128-slice dual-source CT was performed in all 97 patients. In 37 patients (38.1%; 28 men, nine women; mean age, 61.7 ± 20.5 years; mean heart rate, 74.6 ± 2.8 bpm) with significant stenosis at CCTA (lumen diameter reduction >50%), FFR was performed after CCTA, as a reference standard for the evaluation of myocardial perfusion. FFR value ≤0.75 was considered as positive. CTMPI and CCTA were read by two experienced radiologists with consensus, respectively. The effective radiation dose of adenosine-stress single-scan CTMPI was 4.63 ± 2.57 mSv. Compared with FFR, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying significant coronary stenoses were 93.1%, 82.7%, 75.0%, and 95.6%, respectively, on CCTA and 93.1%, 90.3%, 84.4%, and 95.9%, respectively, on CTMPI. On combined CCTA and CTMPI, sensitivity, specificity, PPV, and NPV were 93.1%, 94.2%, 90.0%, and 96.0%, respectively. Adenosine-stress low-dose single scan CTMPI using a 128-slice dual-source CT can provide complementary information on the hemodynamical significance of coronary artery stenosis as well as anatomical information of coronary arteries.

Reduction of Thoracic Aorta Motion Artifact With High-Pitch 128-Slice Dual-Source Computed Tomographic Angiography

Electrocardiogram-gated imaging combined with multi-detector row computed tomography (MDCT) has reduced cardiac motion artifacts, but it was not practical in the emergency setting. The purpose of this study was to evaluate the ability of a high-pitch, 128-slice dual-source CT (DSCT) scanner to reduce motion artifacts in patients admitted to the emergency room. This study comprised 100 patients suspected of having thoracic aorta lesions. We examined 47 patients with the 128-slice DSCT scanner (DSCT group), and 53 patients were examined with a 64-slice MDCT scanner (MDCT group). Six anatomic areas in the thoracic aorta were evaluated. Computed tomography images in the DSCT group were distinct, and significant differences were observed in images of all areas between the 2 groups except for the descending aorta. The high-pitch DSCT scanner can reduce motion artifacts of the thoracic aorta and enable radiological diagnosis even in patients with tachycardia and without breath hold.

Energía dual y angioTC de carótidas: calidad, eliminación de hueso y dosis de radiación de 80/140 kV frente a 100/140 kV

ObjectiveTo study the differences in vascular image quality, bone subtraction, and dose of radiation of dual energy CT angiography of the supraaortic trunks using different tube voltages. Material and methodsWe reviewed the CT angiograms of the supraaortic trunks in 46 patients acquired with a 128-slice dual source CT scanner using two voltage protocols (80/140kV and 100/140kV). The “head bone removal” tool was used for postprocessing. We divided the arteries into 15 segments. In each segment, we evaluated the image quality of the vessels and the effectiveness of bone removal in multiplanar reconstructions (MPR) and in maximum intensity projections (MIP) with each protocol, analyzing the trabecular and cortical bones separately. We also evaluated the dose of radiation received. ResultsOf the 46 patients, 13 were studied using 80/140kV and 33 with 100/140kV. There were no significant differences between the two groups in age or sex. Image quality in four segments was better in the group examined with 100/140kV. Cortical bone removal in MPR and MIP and trabecular bone removal in MIP were also better in the group examined with 100/140kV. The dose of radiation received was significantly higher in the group examined with 100/140kV (1.16 mSv with 80/140kV vs. 1.59 mSv with 100/140kV). ConclusionUsing 100/140kV increases the dose of radiation but improves the quality of the study of arterial segments and bone subtraction.

Efficacy of Lower-Body Shielding in Computed Tomography Fluoroscopy-Guided Interventions

Computed tomography (CT) fluoroscopy-guided interventions pose relevant radiation exposure to the interventionalist. The goal of this study was to analyze the efficacy of lower-body shielding as a simple structural method for decreasing radiation dose to the interventionalist without limiting access to the patient. All examinations were performed with a 128-slice dual source CT scanner (12×1.2-mm collimation; 120kV; and 20, 40, 60, and 80mAs) and an Alderson-Rando phantom. Scatter radiation was measured with an ionization chamber and a digital dosimeter at standardized positions and heights with and without a lower-body lead shield (0.5-mm lead equivalent; Kenex, Harlow, UK). Dose decreases were computed for the different points of measurement. On average, lower-body shielding decreased scatter radiation by 38.2% within a 150-cm radius around the shielding. This decrease is most significant close to the gantry opening and at low heights of 50 and 100cm above the floor with a maximum decrease of scatter radiation of 95.9% close to the scanner's isocentre. With increasing distance to the gantry opening, the effect decreased. There is almost no dose decrease effect at ≥150 above the floor. Scatter radiation and its decrease were linearly correlated with the tube current-time product (r (2)=0.99), whereas percent scatter radiation decrease was independent of the tube current-time product. Lower-body shielding is an effective way to decrease radiation exposure to the interventionalist and should routinely be used in CT fluoroscopy-guided interventions.

Stress and Rest Dynamic Myocardial Perfusion Imaging by Evaluation of Complete Time-Attenuation Curves With Dual-Source CT

This study sought to describe a protocol for myocardial perfusion imaging using dipyridamole stress, with 128-slice dual-source computed tomography (CT), and to assess the ability of CT myocardial perfusion imaging (MPI) to detect abnormal flow reserve and infarction in comparison with nuclear MPI (NMPI). CT MPI has not been previously described with the 128-slice dual-source CT scanner, or with the complete evaluation of dynamic time-attenuation curves of the myocardium. Thirty-five patients underwent a stress CT MPI protocol. Complete time-attenuation curves of the myocardium were acquired using a novel scan mode, which acquires prospectively electrocardiogram (ECG)-triggered axial images at 2 rapidly alternating positions. Myocardial blood flow (MBF) values of fixed and reversible defects obtained were compared between rest and stress. Findings on CT MPI were correlated to NMPI. Perfusion defects detected on CT were correlated to coronary stenoses detected on CT angiography (CTA) and invasive coronary angiography (ICA). There was a 1.5-fold difference between stress (1.21 +/- 0.31 cc/cc/min) and rest (0.82 +/- 0.22 cc/cc/min) MBF in normal tissue. In reversible defects, MBF was 0.65 +/- 0.21 cc/cc/min and 0.63 +/- 0.18 cc/cc/min at stress and rest, respectively. In fixed defects, the MBF was 0.57 +/- 0.22 cc/cc/min at stress and 0.54 +/- 0.23 cc/cc/min at rest. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT MPI for identifying segments with perfusion defects was 0.83, 0.78, 0.79, and 0.82, respectively. ICA results were available for 30 patients. Sensitivity, specificity, PPV, and NPV of CT MPI compared with ICA were 0.95, 0.65, 0.78, and 0.79, respectively. The radiation dose for CT MPI was 9.15 +/- 1.32 mSv for the stress scan and 9.09 +/- 1.40 mSv for the rest scan. Vasodilator-stress CT MPI may be feasible in human subjects at a radiation dose similar to NMPI. It identifies areas of abnormal flow reserve and infarction with a high degree of correlation to NMPI as well as to stenoses detected in CTA and ICA.