Multidetector Computed Tomography Data Research Articles

Three‐dimensional imaging of ventilation dynamics in asthmatics using multiecho projection acquisition with constrained reconstruction

The purpose of this work is to detect dynamic gas trapping in three dimensions during forced exhalation at isotropic high spatial resolution and high temporal resolution using hyperpolarized helium-3 MRI. Ten subjects underwent hyperpolarized helium-3 MRI and multidetector CT. MRI was performed throughout inspiration, breath-hold, and forced expiration. A multiecho three-dimensional projection acquisition was used to improve data collection efficiency and an iterative constrained reconstruction was implemented to improve signal to noise ratio (SNR) and increase robustness to motion. Two radiologists evaluated the dynamic MRI and breath-held multidetector CT data for gas and air trapping, respectively. Phantom studies showed the proposed technique significantly improved depiction of moving objects compared to view-sharing methods. Gas trapping was detected using MRI in five of the six asthmatic subjects who displayed air trapping with multidetector CT. Locations in disagreement were found to represent small to moderate regions of air trapping. The proposed technique provides whole-lung three-dimensional imaging of respiration dynamics at high spatial and temporal resolution and compares well to the current standard, multidetector CT. While multidetector CT can provide information about static regional air trapping, it is unable to depict dynamics in a setting more comparable to a spirometry maneuver and explore the longitudinal time evolution of the trapped regions.

Accuracy analysis of three‐dimensional bone surface models of the forearm constructed from multidetector computed tomography data

We developed an original computer program that simulates upper limb reconstruction surgery using three-dimensional (3D) bone models constructed from computed tomography (CT) data. However, the accuracy of a bone model has not been clarified, and radiation exposure from CT scanning posed a concern. The purpose of this study was to investigate the appropriate CT parameters required to reduce radiation exposure while maintaining the accuracy of 3D models of the forearm bones. Twelve dry forearm bones were used to investigate the accuracy of 3D bone models created from two different CT parameters. The accuracy was evaluated by measuring: (a) the discrepancy between the models constructed from low- and normal-dose CT parameters; (b) the error between actual surface data derived by a contact-type coordinate measuring machine and a 3D bone model; and (c) the difference between a 3D bone model constructed from a bare dry bone and a model constructed from the same bone embedded in a radio-opaque soft tissue substitute. CT dose index (CTDI) and dose-length product (DLP) were recorded to evaluate the radiation exposure. The mean error between bone models constructed from two different CT parameters was 0.04 mm. CTDI and DLP for the normal-radiation dose condition were 9.3 and 563 mGy/cm and those for the low-radiation dose condition were 0.3 and 18 mGy/cm, respectively. The mean error between the bone models and scanning data from contact measurement was 0.45 mm. The mean error between a 3D model constructed from a dry bone and that constructed from the same bone embedded in a radio-opaque soft tissue substitute was 0.06 mm. 3D bone models constructed from low-radiation dose CT data demonstrated the same level of accuracy as those constructed from normal-radiation dose data. The present simulation system can produce 3D bone models with one-thirtieth of the normal radiation dose in the forearm.

Tracheobronchomalacia in Infants and Children: Multidetector CT Evaluation

Tracheobronchomalacia (TBM) is the most common congenital central airway anomaly, but it frequently goes unrecognized or is misdiagnosed as other respiratory conditions such as asthma. Recent advances in multidetector computed tomography (CT) have enhanced the ability to noninvasively diagnose TBM with the potential to reduce the morbidity and mortality associated with this condition. Precise indications are evolving but may include symptomatic pediatric patients with known risk factors for TBM and patients with otherwise unexplained impaired exercise tolerance; recurrent lower airways infection; and therapy-resistant, irreversible, and/or atypical asthma. With multidetector CT, radiologists can now perform objective and quantitative assessment of TBM with accuracy similar to that of bronchoscopy, the reference standard for diagnosing this condition. Multidetector CT enables a comprehensive evaluation of pediatric patients suspected of having TBM by facilitating accurate diagnosis, determining the extent and degree of disease, identifying predisposing conditions, and providing objective pre- and postoperative assessments. In this article, the authors present a step-by-step primer of multidetector CT imaging for evaluating infants and children with suspected TBM, including clinical indications, patient preparation, multidetector CT techniques and protocols, two- and three-dimensional processing of multidetector CT data, and image interpretation. The major aim of this article is to facilitate the reader's ability to successfully employ multidetector CT imaging protocols for evaluation of TBM in infants and children in daily clinical practice.

Nonvascular Mesenteric Disease: Utility of Multidetector CT with 3D Volume Rendering

Creation of isotropic volumes with submillimeter multidetector computed tomography (CT) has expanded interpretative practice to routinely include two-dimensional (2D) and three-dimensional (3D) postprocessing techniques. Currently, 2D multiplanar reformatting, maximum intensity projection, and 3D volume rendering are available on most workstations. Only volume rendering yields a 3D display that depicts all tissue types from any orientation. Utility is not limited to vascular applications, as 3D volume rendering can be used to evaluate neoplastic, infectious, and inflammatory processes that affect the small-bowel mesentery. Specifically, interactive interpretation of multidetector CT data sets with volume rendering can help characterize nonvascular mesenteric disease, elucidate its extent through more comprehensive display, and facilitate the identification of complications.

Midterm Follow-Up of Vertebral Geometry and Remodeling of the Vertebral Bidisk Unit (VDU) After Percutaneous Vertebroplasty of Osteoporotic Vertebral Fractures

The purpose of this study was to investigate geometrical stability and preservation of height gain of vertebral bodies after percutaneous vertebroplasty during 2 years' follow-up and to elucidate the geometric remodeling process of the vertebral bidisk unit (VDU) of the affected segment. Patients with osteoporotic vertebral compression fractures with pain resistant to analgetic drugs were treated with polymethylmethacrylate vertebroplasty. Mean +/- standard error cement volume was 5.1 +/- 2.0 ml. Vertebral geometry was documented by sagittal and coronal reformations from multidetector computed tomography data sets: anterior, posterior, and lateral vertebral heights, end plate angles, and compression index (CI = anterior/posterior height). Additionally, the VDU (vertebral bodies plus both adjacent disk spaces) was calculated from the multidetector computed tomography data sets: anterior, posterior, and both lateral aspects. Patients were assigned to two groups: moderate compression with CI of >0.75 (group 1) and severe compression with CI of <0.75 (group 2). A total of 83 vertebral bodies of 30 patients (7 men, 23 women, age 70.7 +/- 9.7 years, range 40-82 years) were treated with vertebroplasty and prospectively followed for 24 months. In the moderate compression group (group 1), the vertebral heights were stabilized over time at the preinterventional levels. Compared with group 1, group 2 showed a greater anterior height gain (+2.8 +/- 2.2 mm vs. +0.8 +/- 2.0 mm, P < 0.001), better reduction of end plate angle (-4.9 +/- 4.8 degrees vs. -1.0 +/- 2.7 degrees , P < 0.01), and improved CI (+0.12 +/- 0.13 vs. +0.02 +/- 0.07, P < 0.01) and demonstrated preserved anterior height gain at 2 years (+1.2 +/- 3.2 mm, P < 0.01) as well as improved end plate angles (-5.2 +/- 5.0 degrees , P < 0.01) and compression indices (+0.11 +/- 0.15, P < 0.01). Thus, posterior height loss of vertebrae and adjacent intervertebral disk spaces contributed to a remodeling of the VDU, resulting in some compensation of the kyphotic malposition of the affected vertebral segment. Vertebroplasty improved vertebral geometry during midterm follow-up. In severe vertebral compression, significant height gain and improvement of end plate angles were achieved. The remodeling of the VDUs contributes to reduction of kyphosis and an overall improvement of the statics of the spine.

Increased Epicardial Fat Volume Quantified by 64-Multidetector Computed Tomography is Associated With Coronary Atherosclerosis and Totally Occlusive Lesions

The relationship between the epicardial fat volume measured by 64-slice multidetector computed tomography (MDCT) and the extension and severity of coronary atherosclerosis was investigated. Both MDCT and conventional coronary angiography (CAG) were performed in 71 consecutive patients who presented with effort angina. The volume of epicardial adipose tissue (EAT) was measured by MDCT. The severity of coronary atherosclerosis was assessed by evaluating the extension of coronary plaques in 790 segments using MDCT data, and the percentage diameter stenosis in 995 segments using CAG data. The estimated volume of EAT indexed by body surface area was defined as VEAT. Increased VEAT was associated with advanced age, male sex, degree of metabolic alterations, a history of acute coronary syndrome (ACS) and the presence of total occlusions, and showed positive correlation with the stenosis score (r=0.28, P=0.02) and the atheromatosis score (r=0.67, P<0.0001) of the coronary arteries. Multiple logistic regression analysis revealed an increased VEAT (>or=50 cm(3)/m(2)) to be the strongest independent determinant of the presence of total occlusions (odds ratio 4.64, P=0.02). VEAT correlates with the degree of metabolic alterations and coronary atheromatosis. Excessive accumulation of EAT might contribute to the development of ACS and coronary total occlusions.

Preoperative Radiologic and Postoperative Pathologic Risk Factors for Early Intra-Hepatic Recurrence in Hepatocellular Carcinoma Patients Who Underwent Curative Resection

PurposeThe risk of hepatocellular carcinoma (HCC) recurrence must be considered ahead of surgery. This study was undertaken to identify pre-operative risk factors for early intrahepatic recurrence of HCC after curative resection in a large-scale.Materials and MethodsWe retrospectively reviewed the preoperative three-phase multi-detector CT (MDCT) and laboratory data for 240 HCC patients who underwent curative resection; tumor size, number, gross shape, capsule integrity, distinctiveness of tumor margin, portal vein thrombosis (PVT), alpha-fetoprotein level (AFP), and protein induced by vitamin K absence-II (PIVKA-II) levels were assessed. Surgical pathology was reviewed; tumor differentiation, capsule, necrosis, and micro-vessel invasion were recorded.ResultsHCC recurred in 61 patients within six months (early recurrence group), but not in 179 patients (control group). In univariate analysis, large tumor size (p = 0.018), shape (p = 0.028), poor capsule integrity (p = 0.046), elevated AFP (p = 0.015), and PIVKA-II (p = 0.008) were significant preoperative risk factors. Among the pathologic features, PVT (p = 0.023), Glisson's capsule penetration (p = 0.033), microvascular invasion (p < 0.001), and poor differentiation (p = 0.001) showed statistical significance. In multivariate analysis, only the histopathologic parameters of microvascular invasion and poor differentiation achieved statistical significance.ConclusionPreoperative CT and laboratory parameters showed limited value, while the presence of microscopic vascular tumor invasion and poorly differentiated HCC correlated with higher risk of early recurrence after curative resection.

Measurement of Kidney Volume with Multi-Detector Computed Tomography Scanning in Young Korean

PurposeKidney volume is regarded as the most precise indicator of kidney size. However, it is not widely used clinically, because its measurement is difficult due to the complex kidney shape. We attempted to evaluate the normal kidney volume in young Korean men by using multi-detector computed tomography (MDCT).Materials and MethodsWe retrospectively reviewed MDCT data of young Korean men (113 patients). After data processing, we measured the volume and length of the kidneys. Body parameters (height, body weight, body-surface area, and total body water) and laboratory data were collected. Glomerular filtration rate (GFR) was calculated using Cockcroft-Gault (CG) equation.ResultsThe mean kidney volume was 205.29 ± 36.81 cm3; and mean kidney length was 10.80 ± 0.69 cm. The former correlated significantly with height, body weight, body-surface area, and total body water (p < 0.05, correlation coefficient : γ = 0.328, 0.649, 0.640, and 0.638, respectively). The latter also correlated significantly with all body indexes, however the correlation was weaker, except with height (p < 0.05, correlation coefficient : γ = 0.457, 0.473, 0.505, and 0.503, respectively). Only kidney volume significantly predicted estimated GFR (adjusted R2 = 0.431, F = 85.90 and p < 0.05).ConclusionThe kidney volume measured with MDCT is correlated well with body parameters, and is useful to predict renal function.

Assessment of global left ventricular systolic function with multidetector CT and 2-d echocardiography: a comparison between reconstructions of 1 mm and 2 mm slice thickness at MDCT

To compare multidetector computed tomography (MDCT) and two-dimensional transthoracic echocardiography (2DE) for left ventricular ejection fraction (EF); and to make comparison between reconstructions of 1-mm and 2-mm slice thickness at MDCT in left ventricular analysis by using a semiautomated segmentation algorithm. In 43 patients global left ventricular systolic function was assessed by using both MDCT and 2DE. Functional MDCT data sets were reconstructed in 20 cardiac phases (0-95%) with both 1-mm and 2-mm slice thickness.With semi-automatic left ventricle segmentation, end-diastolic volume (EDV), endsystolic volume (ESV) and EF were calculated seperately for both 1-mm and 2-mm reconstructions. On MDCT with 1-mm slice thickness, mean EF was 66.8 +/- 5.6 %, mean EDV was 133.7 +/- 38.9 mL, and mean ESV was 45.1 +/- 17.9 mL, these values for 2-mm slice thickness were 66.2 +/- 5.6 %, 133.5 +/- 39.6 mL, and 45.9 +/- 18.3 mL, respectively. On 2DE, mean EF was 66.7 +/- 5.7 %, mean EDV was 98.7 +/- 42.1 mL, and mean ESV was 33.6 +/- 18.7 mL. There was no difference between EF values calculated with 1-mm and 2-mm reconstructions and 2DE (P = 0.83 and P = 0.3705, respectively). However, EDV and ESV values calculated by MDCT were significantly higher than those obtained by 2DE (P < 0.0001). There was a good correlation between MDCT and 2DE in the evaluation of left ventricular EF. At MDCT left ventricular ESV was statistically smaller, EF was statistically greater by using 1-mm rather than 2-mm slice thickness. However, these differences are not clinically relevant.

Patient‐specific dose estimation for pediatric chest CT

Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9-18.2 kg) were created based on the patients' actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structures were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120 kVp, 70 or 75 mA, 0.4 s gantry rotation period, pitch of 1.375, 20 mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7-5.3 mSv/100 mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4-12.6 mGy/100 mAs and 11.2-13.3 mGy/100 mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%-18%) and for partially or indirectly exposed organs (11%-77%). Normalized effective dose correlated weakly with body weight (correlation coefficient: r=-0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=-0.99, heart: r=-0.93); these strong correlation relationships can be used to estimate patient-specific organ dose for any other patient in the same size/protocol group who undergoes the chest scan. In summary, this work reported the first assessment of dose variations across pediatric CT patients in the same size/protocol group due to the variability of patient anatomy and body habitus and provided a previously unavailable method for patient-specific organ dose estimation, which will help in assessing patient risk and optimizing dose reduction strategies, including the development of scan protocols.

Comparing culprit lesions in ST-segment elevation and non-ST-segment elevation acute coronary syndrome with 64-slice multidetector computed tomography

Background Classifying acute coronary syndrome (ACS) as ST elevation ACS (STE-ACS) or non-ST elevation ACS (NSTE-ACS) is critical for clinical prognosis and therapeutic decision-making. Assessing the differences in composition and configuration of culprit lesions between STE-ACS and NSTE-ACS can clarify their pathophysiologic differences. Objective This study focused on evaluating the ability of 64-slice multidetector computed tomography (MDCT) to investigate these differences in culprit lesions in patients with STE-ACS and NSTE-ACS. Methods Of 161 ACS cases admitted, 120 who fit study criteria underwent MDCT and conventional coronary angiography. The following MDCT data were analyzed: calcium volume, Agatston calcium scores, plaque area, plaque burden, remodeling index, and plaque density. Results The MDCT angiography had a good correlation with conventional coronary angiography regarding the stenotic severity of culprit lesions ( r = 0.86, p < 0.001). The STE-ACS culprit lesions ( n = 54) had significantly higher luminal area stenosis (78.6 ± 21.2% vs. 66.7 ± 23.9%, p = 0.006), larger plaque burden (0.91 ± 0.10 vs. 0.84 ± 0.12, p = 0.007) and remodeling index (1.28 ± 0.34 vs. 1.16 ± 0.22, p = 0.021) than those with NSTE-ACS ( n = 66). The percentage of expanding remodeling index (remodeling index >1.05) was significantly higher in the STE-ACS group (81.5% vs. 63.6%, p = 0.031). The patients with STE-ACS had significantly lower MDCT density of culprit lesions than patients with NSTE-ACS (25.8 ± 13.9 HU vs. 43.5 ± 19.1 HU, p < 0.001). Conclusions Sixty-four-slice MDCT can accurately evaluate the stenotic severity and composition of culprit lesions in selected patients with either STE-ACS or NSTE-ACS. Culprit lesions in NSTE-ACS patients had significantly lower luminal area stenosis, plaque burden, remodeling index and higher MDCT density, which possibly reflect differences in the composition of vulnerable culprit plaques and thrombi.

Abstract 687: Cardiac Imaging with Multi-Slice Computed Tomography and Echocardiography to Guide Left Ventricular Lead Placement in Resynchronization Therapy. The CAMERA Trial

Cardiac resynchronization (CRT) is associated with reverse ventricular remodeling and improved clinical outcomes, but is not successful in all patients. We looked at the feasibility of combined non-invasive imaging of the coronary veins and assessment of left ventricular dyssynchrony prior to pacemaker implantation and whether this combination would improve procedural success and patient outcome. Heart failure patients with standard indications for CRT were randomized to cardiac Multi-Detector CT (MDCT) plus Doppler echocardiographic assessment of left ventricular dyssynchrony versus conventional management prior to CRT. Co-registration of MDCT and tissue synchronization imaging data using a novel software program was performed and the results were used to optimize left ventricular lead placement for patients in the non-invasive imaging arm. 21 patients were enrolled with 9 patients randomized to the contemporary non-invasive imaging strategy and 12 patients randomized to the control group. MDCT correctly identified 19 of 24 (79%) coronary venous branches ≥ 2 mm in diameter when compared to invasive coronary venography. Patients in the non-invasive imaging group had a significant improvement in the 6 minute walk time on 6 month follow up (76.1 ± 48.4 meters vs 20.0 ± 64.8 meters, p = 0.04). Improvements in NYHA functional class and LV remodeling at 6 months were not significantly different in the non-invasive imaging and control arms. Left ventricular lead placement was successful in all patients, however more patients in the non-invasive imaging arm demonstrated LV lead placement in the most delayed or adjacent myocardial segment (8 of 9 vs 6 of 12, p = 0.09). Those patients with “optimal” lead placement showed a trend towards improved 6 minute walk times and improvement in left ventricular function 6 months after biventricular pacing. An imaging-guided strategy with coregistration of MDCT coronary venous anatomy and delayed myocardial segments by tissue Doppler echocardiography prior to CRT is feasible and may improve patient outcomes by facilitating optimal LV lead placement.

Abdominal Aorta: Evaluation with Dual-Source Dual-Energy Multidetector CT after Endovascular Repair of Aneurysms—Initial Observations

To evaluate the possible radiation dose reduction facilitated by using dual-energy (DE) multidetector computed tomography (CT) after endovascular repair of abdominal aortic aneurysms (AAAs). This prospective study was HIPAA compliant and institutional review board approved. Twenty-two patients who previously had undergone endovascular repair of AAAs underwent 24 DE multidetector CT examinations, which were performed with a 64-detector scanner. Initial nonenhanced CT was followed by arterial phase and venous phase acquisitions. Virtual nonenhanced, pure 80-kVp, and weighted-average peak voltage CT data sets were generated from the venous acquisition. Two independent readers interpreted the virtual nonenhanced and DE weighted-average CT data for the presence or absence of endoleaks. These interpretations were compared with the clinical interpretations of the data performed by a different radiologist by using true nonenhanced, arterial phase, and venous phase data. Region-of-interest measurements of the abdominal aorta and of the region of the endoleaks were obtained. Effective radiation dose was calculated. Both independent readers' interpretations of the virtual nonenhanced and weighted-average venous CT data revealed six type II endoleaks. There were no false-positive or false-negative findings. Aortic attenuation during the arterial, 80-kVp venous, and weighted-average data acquisitions were 288, 213, and 150 HU, respectively. The attenuation of the endoleaks was higher during the 80-kVp acquisition (P < .03) than during the arterial phase and weighted-average venous phase acquisitions. The mean effective dose for DE venous phase CT was 11.1 mSv compared with 27.8 mSv for standard triple-phase CT with a single-source configuration. Preliminary observations suggest that obtaining DE multidetector CT data by using a single 60-second contrast material-enhanced acquisition may be all that is required for surveillance after endovascular repair of AAA.

Improved Visualization of Artificial Pulmonary Nodules with a New Subvolume Rendering Technique

The detection of small nodules in pulmonary multidetector computed tomography (MDCT) data sets is challenging, and there is a need for visualization techniques that can improve reader sensitivity and efficiency. We have developed a subvolume rendering technique ("Softslice") with nonlinear, symmetrical modulation of the relative signal intensity along the viewing direction. Our hypothesis was that this technique might provide an advantageous visual differentiation between nodules and overlapping vessels in pulmonary MDCT subvolumes. To compare the Softslice subvolume rendering technique and maximum intensity projection (MIP) rendering for visualization of artificial pulmonary nodules in MDCT data sets. Virtual, artificial pulmonary nodules were created with custom-made software. The nodules had the same signal intensity as pulmonary vessels. Approximately 50 nodules with diameter 2-7 mm were inserted in the Digital Imaging and Communications in Medicine (DICOM) image files of pulmonary MDCT data sets obtained without intravenous contrast. Each data set contained approximately 300 slices with 1-mm slice spacing. Four types of subvolumes were rendered: MIP with 10- and 20-mm subvolume thickness, and Softslice with 20- and 30-mm subvolume thickness. Three radiologists performed readings with free scrolling using 1-, 4- or 8-mm increments between subvolume positions. No significant differences in the number of detected nodules were found between the different renderings with free scrolling using 1- and 4-mm increments. When 8-mm increment was used, nodule detection with the 30-mm Softslice rendering was significantly superior to the other renderings (P = 0.012 vs. MIP 10 mm, P = 0.018 vs. MIP 20 mm, P = 0.021 vs. Softslice 20 mm). When the subvolume increments were changed from 4 mm to 8 mm, the most marked reduction in the number of detected nodules was seen for MIP subvolumes with 10-mm thickness (P = 0.018). The Softslice rendering technique is promising for the detection of pulmonary nodules in MDCT data sets, and may allow more efficient reading than the standard MIP subvolume technique. With 10-mm MIP rendering, the detection rate for small pulmonary nodules substantially influenced by the incremental distance between subvolumes positions.

Calcified Vascular Plaque Specimens: Assessment with Cardiac Dual-Energy Multidetector CT in Anthropomorphically Moving Heart Phantom

To evaluate whether dual-energy multidetector computed tomography (CT) with image postprocessing techniques enhances accuracy of calcified plaque quantification beyond the scope of single-energy multidetector CT, by using optical coherence tomography (OCT) as the reference standard. Four atherosclerotic specimens were examined with 64-section dual-energy multidetector CT by using a novel dual-detector "double-decker" design, with stacked high- and low-energy detector arrays with 32 x 0.625-mm collimation, at 140 kVp and 400 mAs, acquiring simultaneous and isopedic low- and high-energy data sets. Additionally, combined-energy data sets were calculated, and an enhancement algorithm was proposed. Cardiac motion was simulated by an anthropomorphically moving phantom, and OCT was used as a reference standard for plaque quantification. Univariate general linear model (GLM) analysis was used to compare sizes of plaque calcifications determined with OCT with those determined with dual-energy multidetector CT, and the significance of factors such as cardiac motion was assessed. GLM analysis revealed that plaque quantification based on low-, high-, and combined-energy data sets differed significantly from that based on OCT (P < .001). Greater data variation occurred in smaller (<8 mm(2)) and larger (>12 mm(2)) calcifications. Comparison of calcified plaque sizes determined with OCT with those determined with the dual-energy multidetector CT enhancement algorithm revealed no significant difference (P = .550). Cardiac activity led to a slight increase in data variation in regard to OCT for corresponding static (mean, 10.2% +/- 3.2 [standard deviation]) and dynamic (13.8% +/- 4.9) dual-energy multidetector CT data sets. Dual-energy multidetector CT with novel postprocessing techniques enhanced accuracy of calcified plaque quantification by reducing effects of tissue blooming and beam hardening beyond single-energy multidetector CT.

Imaging in Intestinal Ischemic Disorders

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel and/or colon. The incidence of bowel ischemia is increasing for a number of reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have contributed greatly to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this review, advances in multidetector computerized tomography, magnetic resonance, and ultrasound in the detection of intestinal ischemia are highlighted and placed in the context of expeditious patient management.

Ventricular septal rupture complicating myocardial infarction: Comprehensive assessment of cardiac coronary arteries, anatomy, perfusion and function by multidetector computed tomography

38-year-old man was referred for electrocardiogram (ECG)-gated multidetector computed tomography (MDCT) coronary angiography following detection of ventricular septal rupture (VSR) on transthoracic echocardiography 24 h after admission for an acute inferior wall myocardial infarction. He had been treated with primary angioplasty and stenting of a tight distal right coronary stenosis. Detailed, comprehensive evaluation of the VSR, myocardium and coronary arteries was performed with ECG-gated MDCT coronary angiography using a Brilliance 16-slice scanner (Philips Medical Systems, USA). MDCT coronary angiography showed a patent stent and a proximal heterogeneous plaque of borderline significance (Figure 1). The measured global left ventricular function, using the MDCT data, disclosed a mildly reduced ejection fraction of 47%. Regional functional analysis using cine films of the MDCT data depicted regional akinesis of the inferior and inferoseptal mid- and basal segments, manifesting as a marked reduction in myocardial thickening during systole (Video 1 – click here to view). Furthermore, first-pass myocardial perfusion analysis depicted a well-defined, nearly transmural enhancement defect parallel to the akinetic myocardial region (Figure 2). Further detailed analysis of the interventricular septum at end-diastole showed a full-thickness rupture in the mid-inferior septum (Figures 3A and 3B). Of note, the septal rupture occurred at the junction of the normally enhancing anterior septum and the hypoperfused, necrotic, inferior septum and inferior myocardial segments, indicating that this junction line appears to act as a locus minoris resistentiae. The VSR demonstrated near-complete lumen obliteration during peak systole (Figures 3A and 3B), suggesting that at least part of the bordering myocardium (anterior septum) was contracting and, thus, viable. Because the described VSR was small and of no hemodynamic significance, based on imaging findings, it was managed conservatively with follow-up echocardiography. There was no change during a three-month follow-up period.

Added Diagnostic Value of Multiplanar Reformation of Multidetector CT Data in Patients with Suspected Appendicitis

Computed tomography (CT) is an accurate and effective modality for the diagnosis and staging of appendicitis. CT provides rapid and complete evaluation of patients with suspected appendicitis and clearly demonstrates the typical findings of appendicitis, including a distended appendix, periappendiceal fat stranding, an appendicolith, and focal thickening of the cecum. Identification of an inflamed appendix at CT may be difficult in certain patients (eg, patients with scanty intraabdominal fat, an unusual location of the cecum and appendix, prominent cecal wall thickening and pericecal fat stranding, small bowel dilatation, or abscess formation adjacent to the right adnexa). In such cases, multiplanar reformation (MPR) of multidetector CT data may provide improved appendiceal visualization and increase the physician's confidence in diagnosing appendicitis. Moreover, the use of MPR in addition to conventional CT may provide improved visualization of the normal appendix and thereby enhance confidence in excluding appendicitis and diagnosing diseases that mimic appendicitis. Consequently, the radiologist should obtain MPR images in the evaluation of patients with suspected appendicitis to help ensure the correct diagnosis.

64 slice MDCT generally underestimates coronary calcium scores as compared to EBT: A phantom study

The objective of our study was the determination of the influence of the sequential and spiral acquisition modes on the concordance and deviation of the calcium score on 64-slice multi-detector computed tomography (MDCT) scanners in comparison to electron beam tomography (EBT) as the gold standard. Our methods and materials were an anthropomorphic cardio CT phantom with different calcium inserts scanned in sequential and spiral acquisition modes on three identical 64-slice MDCT scanners of manufacturer A and on three identical 64-slice MDCT scanners of manufacturer B and on an EBT system. Every scan was repeated 30 times with and 15 times without a small random variation in the phantom position for both sequential and spiral modes. Significant differences were observed between EBT and 64-slice MDCT data for all inserts, both acquisition modes, and both manufacturers of MDCT systems. High regression coefficients (0.90-0.98) were found between the EBT and 64-slice MDCT data for both scoring methods and both systems with high correlation coefficients (R2>0.94). System A showed more significant differences between spiral and sequential mode than system B. Almost no differences were observed in scanners of the same manufacturer for the Agatston score and no differences for the Volume score. The deviations of the Agatston and Volume scores showed regression dependencies approximately equal to the square root of the absolute score. The Agatston and Volume scores obtained with 64-slice MDCT imaging are highly correlated with EBT-obtained scores but are significantly underestimated (-10% to -2%) for both sequential and spiral acquisition modes. System B is more independent of acquisition mode to calcium score than system A. The Volume score shows no intramanufacturer dependency and its use is advocated versus the Agatston score. Using the same cut points for MDCT-based calcium scores as for EBT-based calcium scores can result in classifying individuals into a too low risk category. System information and scanprotocol is therefore needed for every calcium score procedure to ensure a correct clinical interpretation of the obtained calcium score results.

Diagnostic Accuracy of Image Postprocessing Methods for the Detection of Coronary Artery Stenoses by Using Multidetector CT1

To retrospectively evaluate the diagnostic accuracy of multidetector computed tomography (CT) coronary angiography for detection of hemodynamically significant (>or=50%) stenoses by using various image postprocessing methods, with conventional coronary angiography as the reference standard. The analysis used data from previous studies, use of which had been approved by the Institutional Review Board. Sixteen-section multidetector CT data sets for 40 patients (30 men, 10 women; mean age 56 years +/- 8; mean heart rate, 61 beats per minute +/- 6) were evaluated. Six independent investigators evaluated the data sets for the presence of stenoses with diameter reduction of 50% or more, by using either exclusively transverse images, free oblique multiplanar reconstructions (MPRs), free oblique maximum intensity projections (MIPs, 5 mm thick), prerendered curved MPRs, prerendered curved MIPs, or prerendered three-dimensional volume rendered reconstructions (VRTs). Evaluation results were compared with conventional coronary angiography for each artery in a blinded fashion (chi(2) test). Overall, 35 coronary artery stenoses were present. Percentage of evaluable arteries and accuracy for detecting stenosis (percentages of accurately classified arteries were, respectively, 99% and 88% for transverse, 99% and 91% for oblique MPR, 94% and 86% for oblique MIP, 94% and 83% for curved MIP, 93% and 81% for curved MPR, and 91% and 73% for VRT). Accuracy was significantly higher for oblique MPR than for curved MPR (P=.01), curved MIP (P=.03), and VRT (P<.001). The evaluation of multidetector CT coronary angiography with interactive image display methods, especially interactive oblique MPRs, permits higher diagnostic accuracy than evaluation of prerendered images (curved MPR, curved MIP, or VRT images).