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Objective: To evaluate the clinical impact of automatic tube voltage selection on chest CT angiography (CTA)., Methods: Ninety-three patients were prospectively evaluated with a CT protocol aimed at comparing two successive CTAs acquired under similar technical conditions except for the kV selection: (1) the initial CTA was systematically obtained at 120 kVp and 90 ref mAs; (2) the follow-up CTA was obtained with an automatic selection of the kilovoltage (Care KV; Siemens Healthcare) for optimised CTA., Results: At follow-up, 90 patients (97 %) underwent CTA with reduced tube voltage, 100 kV (n = 26; 28 %) and 80 kV (n = 64; 69 %), resulting in a significant dose-length-product reduction (follow-up: 87.27; initial: 141.88 mGy.cm; P < 0.0001; mean dose reduction: 38.5 %) and a significant increase in the CNR at follow-up (follow-up: 11.5 ± 3.5 HU; initial: 10.9 ± 3.7 HU; P = 0.03). The increase in objective image noise at follow-up (follow-up: 23.2 ± 6.7 HU vs. 17.8 ± 5.1 HU; P < 0.0001) did not alter the diagnostic value of images., Conclusion: Automatic tube voltage selection reduced the radiation dose delivered during chest CT angiograms by 38.5 % while improving the contrast-to-noise ratio of the examinations., Key Points: • As low a dose as possible must be used for CT angiography. • Automatic tube voltage selection permits reduced patient exposure. • Lowering the kVp enables increased intravascular attenuation. • Automatic tube voltage selection does not compromise the overall image quality.

Purpose: To provide quantitative information on emphysema in asymptomatic smokers in correlation with pulmonary function tests (PFT)., Patients and Methods: The study population included 75 smokers (current smokers: n=39; ex-smokers: n=36) and 25 nonsmokers who underwent volumetric high-resolution CT of the chest with automated quantification of emphysema and PFTs., Results: Current smokers had a higher percentage of emphysema in the right lung (P=0.041) and right upper lobe (P=0.037). The overall percentage of emphysema did not differ according to the Gold stage (P=0.77). Smokers with emphysema had significantly higher mean values of FRC (P=0.012), RV (<0.0001) and TLC (P=0.0157) than smokers without emphysema but no significant differences were found in neither the mean values of TLCO nor in expiratory flows (P>0.05). Correlations were found between the percentage of emphysema and (a) cigarette consumption of current (r=0.34215; P=0.0330) and ex-smokers (r=0.44104; P=0.0071); and (b) alterations of TLC, FRC, RV and DLCO of smokers., Conclusion: Quantitative CT allows recognition of regional specificities and subclinical functional alterations in smokers with emphysema., (Copyright © 2013. Published by Elsevier Masson SAS.)

Purpose: To evaluate image quality of low-voltage chest computed tomographic (CT) angiography with raw data-based iterative reconstruction (sonogram-affirmed iterative reconstruction) in comparison with image quality of standard-dose standard-voltage filtered back projection (FBP) CT., Materials and Methods: This prospective study was approved by the institutional review board, and the informed consent requirement was waived. Eighty consecutive patients who were referred for follow-up chest CT angiography underwent reduced-dose CT (hereafter, T2 examination) under technical conditions similar to those of the initial examination (hereafter, T1 examination), except the voltage selection was reduced by 20 kV with adaptation of the tube current to ensure a 50% reduction in CT dose index, and regular FBP was replaced by iterative reconstruction with sonogram-affirmed iterative reconstruction. The two techniques were compared by using paired tests (Student t test, Wilcoxon test, or McNemar test, according to the nature of variables)., Results: When compared with standard-dose T1 studies, reduced-dose T2 images showed: (a) significantly less objective noise at the level of the trachea on mediastinal and lung parenchymal images (P < .001) and no significant difference in objective noise at the level of the aorta on mediastinal images (P = .507); (b) significantly higher signal-to-noise and contrast-to-noise (P < .001) ratios; (c) similar visual perception of noise on mediastinal (P = .132) and lung (P = .366) images, mainly rated as moderate; and (d) similar overall subjective image quality (P = .405)., Conclusion: Raw data-based iterative reconstruction yielded equivalent subjective and improved objective image quality of low-voltage half-dose CT angiograms compared with standard-dose FBP CT images for an average dose-length product of less than 80 mGy · cm in this population., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120414/-/DC1., (© RSNA, 2013.)

Purpose: To determine the energy levels that provide optimal imaging of thoracic circulation at dual-energy computed tomographic (CT) angiography with reduced iodine load in comparison with a standard technique., Materials and Methods: The institutional review board approved the study with waiver of patient consent. Eighty patients underwent a dual-source, dual-energy CT examination after administration of low-concentration contrast material (170 mg of iodine per milliliter), and eight series of images were reconstructed, including the original polychromatic images at 80 and 140 kV and six series of virtual monochromatic spectral images at 50, 60, 70, 80, 90, and 100 keV. For each vascular compartment, the energy level that provided optimal evaluation on virtual monochromatic spectral images was determined, and these series were compared with the polychromatic dual-energy images and with standard chest CT images that were used as controls. Comparisons between groups were performed by using the paired Student t test for continuous variables and the McNemar test for categorical variables. Comparisons between dual-energy and standard CT images were performed by using the unpaired Student t test for continuous variables and the χ(2) test for categorical variables., Results: For the aorta, pulmonary arteries, and veins, the reconstruction at 60 keV provided adequate attenuation without marked beam-hardening artifacts in 90% of patients, with the highest contrast-to-noise and signal-to-noise ratios, the lowest level of subjective noise, and no significant differences with images at 80 kV (mean energy, 54 keV). For the superior vena cava and brachiocephalic veins, the reconstructions at 100 keV enabled artifact-free analysis of the perivascular anatomic zone without a significant difference with images at 140 kV (mean energy, 92 keV). Compared with standard CT images acquired after administration of a 35% iodinated contrast agent, there was a statistically significant reduction in the frequency of artifacts around systemic veins at 100 keV (P < .001) and similar overall image quality for central vessels at 60 keV (P > .05)., Conclusion: An optimal analysis of thoracic circulation can be achieved on virtual monochromatic spectral images at 60 keV and 100 keV and on the original polychromatic images at 80 kV and 140 kV., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120195/-/DC1., (RSNA, 2013)

Purpose: To establish the radiation dose level for single- and dual-source thoracic CT scans in daily practice., Materials and Methods: The dose levels delivered during 634 consecutive examinations over a period of 2 months were recorded. The CT scans were performed using: (a) a standard protocol (single source, single energy [group 1]: n=266; dual source, single energy [group 2]: n=276; (b) with prospective ECG synchronisation [group 3]: n=13; or (c) with dual energy [group 4]: n=79. All the acquisitions included kilovoltage selection depending on the weight and automatic milliamperage modulation., Results: The mean DLP of the standard protocols was 97.12 mGycm (group 2; BMI=23.1kg/m(2)) and 211.1 mGycm (group 1; BMI=27.3kg/m(2)), the choice of protocol depending on the diameter of the thorax relative to the diameter of the field of the second source, and therefore on the patient's morphotype. When imaging included examination of the proximal and middle coronary arteries (group 3), the mean DLP was 105.5 mGycm. Morphological and functional imaging (group 4) was obtained with a mean DLP of 404.3 mGycm., Conclusion: Depending on the objective of the protocol, the mean DLP varied from 97.12 to 404.3 mGycm., (Copyright © 2012 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.)

Purpose: To evaluate the tolerance and level of enhancement achievable after inhalation of stable krypton., Materials and Methods: This study was approved by the institutional review board and the local ethics committee. Written informed consent was obtained from all subjects. The study was planned as a Fleming two-stage design, enabling one to assess the effectiveness of a newer treatment or technique on a small number of patients. At the end of each stage, the results are computed, and the trial can be stopped if the effectiveness is less than a minimum success rate or greater than an expected success rate. After informed consent was obtained, a total of 32 patients (ie, two successive series of 16 patients each) with severe emphysema underwent a dual-source, dual-energy chest computed tomographic (CT) examination after inhalation of a mixture of stable krypton (80%) and oxygen (20%), with reconstruction of diagnostic and ventilation images. For each patient, two regions of interest were selected on a diagnostic image, one in a region of severe emphysema (presumed to be poorly ventilated or not ventilated) and a second one in a region devoid of structural abnormalities (presumed to be normally ventilated), with measurements of attenuation values on the corresponding ventilation image., Results: All examinations were successfully performed, without adverse effects. Differences in attenuation between normal lung and emphysematous areas were found in 28 patients (88%; 95% confidence interval: 71%, 96.5%). The maximal level of attenuation within normal lung was 18.5 HU. Krypton attenuation difference between normal and emphysematous lung was significant, with a median value of 51.8% (P < .001)., Conclusion: The level of enhancement after inhalation of krypton and its excellent clinical tolerance makes this gas eligible for ventilation CT examinations., (© RSNA, 2012.)

Objectives: To evaluate the accessibility of coronary arteries from chest CT examinations acquired without ECG gating or beta-blockade., Materials and Methods: Two hundred forty-two patients (median heart rate: 81.7 bpm) underwent a non-ECG-gated CT examination with high pitch and high temporal resolution. Image analysis was obtained by consensus between two readers., Results: The percentage of accessible segments was 88% at the proximal level (i.e. 4 segments), 75% at the proximal and mid-segment level (i.e. 7 segments), and 61% and 48% when considering 10 and 15 segments, respectively. The mean (± SD) number of accessible segments per patient was 3.5 ± 0.78 and 5.2 ± 1.50 when considering four and seven segments per patient, respectively. The percentage of patients with four segments accessible was 67% (126/242), decreasing to 23% (55/242) with seven segments accessible and 3% (7/242) with ten segments accessible, while the entire coronary artery tree was not accessible for any of the patients. No significant difference was found in the patients' mean hearts with four, seven, or ten accessible segments (P = 0.4897)., Conclusion: Diagnostic image quality was attainable at the level of proximal segments in 67% of patients, while proximal and mid-coronary segments were accessible in 23% of patients. Main Messages • High-pitch and high-temporal resolution scanning modes make accessible proximal coronary arteries on non ECG-gated chest CT angiograms • It is not necessary to administer beta-blockers to achieve good results. • Tobacco-related cardiovascular disorders could benefit from this scanning mode.

Purpose: To evaluate whether dual-energy CT angiography (DE-CTA) could identify links between morphologic and functional abnormalities in chronic pulmonary thromboembolism (CPTE)., Materials and Methods: Seventeen consecutive patients with CPTE without underlying cardio-respiratory disease were investigated with DE-CTA. Two series of images were generated: (a) transverse diagnostic scans (i.e., contiguous 1-mm thick averaged images from both tubes), and (b) perfusion scans (i.e., images of the iodine content within the microcirculation; 4-mm thick MIPs). Two radiologists evaluated by consensus the presence of: (a) pulmonary vascular features of CPTE and abnormally dilated systemic arteries on diagnostic CT scans, and (b) perfusion defects of embolic type on perfusion scans., Results: Diagnostic examinations showed a total of 166 pulmonary arteries (166/833; 19.9%) with features of CPTE, more frequent at the level of peripheral than central arteries (8.94 vs 0.82; p<0.0001), including severe stenosis with partial (97/166; 58.4%) or complete (20/166; 12.0%) obstruction, webs and bands (37/166; 22.3%), partial filling defects without stenosis (7/166; 4.2%), focal stenosis (4/166; 2.4%) and abrupt vessel narrowing (1/166; 0.6%). Perfusion examinations showed 39 perfusion defects in 8 patients (median number: 4.9; range: 1-11). The most severe pulmonary arterial features of CPTE were seen with a significantly higher frequency in segments with perfusion defects than in segments with normal perfusion (p<0.0001). Enlarged systemic arteries were observed with a significantly higher frequency ipsilateral to lungs with perfusion defects (9/12; 75%) compared with lungs without perfusion defects (5/22; 22.7%) (p=0.004)., Conclusion: Dual-energy CTA demonstrates links between the severity of pulmonary arterial obstruction and perfusion impairment, influenced by the degree of development of the systemic collateral supply., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Identifying the role of fungi present in the domestic environment in the development of interstitial pneumonia can be a difficult clinical problem. We report a case of interstitial lung disease case occurring in a 53-year-old patient. He presented with profound hypoxemia (PaO(2) 54mmHg). Chest CT showed diffuse ground glass opacities. Initial blood tests for allergy and autoimmune disease were negative. Faced with a worsening of his clinical status after returning home he was hospitalized several times. At fibreoptic bronchoscopy, multiple white deposits were observed. Bronchoalveolar lavage with differential cell count was performed, revealing a 23% lymphocytosis. Serology for specific household molds showed moderate reaction to various molds found in homes, especially Stachybotrys chartarum. Pulmonary function tests revealed a moderate restrictive pattern with impaired diffusion of carbon monoxide and a bronchiolocentric interstitial pneumonia was found at lung biopsy. After a permanent move to a new residence, clinical parameters, radiological, biological and functional normalized. The final diagnosis was interstitial lung disease related to mycotoxins of S. Chartarum. The diagnosis of hypersensitivity pneumonitis to domestic mold or interstitial lung disease secondary to mycotoxins should be considered in patients presenting with interstitial pneumonia and requires specific investigations to ensure that an environmental cause with an allergic or toxic role is not missed., (Copyright © 2011 SPLF. Published by Elsevier Masson SAS. All rights reserved.)

Rationale and Objectives: The aim of this study was to evaluate whether the spectral characterization of the iodine content of lung microcirculation could help identify ground-glass opacity (GGO) of vascular origin., Materials and Methods: Thirty-five consecutive patients with GGO of bronchioloalveolar (group 1; n = 24) and vascular (group 2; n = 11) origin underwent dual-energy multi-detector computed tomographic angiography of the chest using a standard injection protocol. For each patient, two radiologists evaluated by consensus the presence, location, and extent of GGO on diagnostic computed tomographic scans (ie, contiguous 1-mm-thick averaged images from both tubes) and characteristics of the corresponding areas on perfusion scans., Results: A total of 443 segments with GGO were depicted on the diagnostic scans (group 1, n = 231; group 2, n = 212), always intermingled with areas of normal lung attenuation, with a mean of 12.7 segments with GGO per patient. Areas of GGO were located at the level of the upper lobes (n = 128), middle lobe and/or lingula (n = 81), and lower (n = 234) lobes, involving <25% (n = 165), 25% to 50% (n = 103), 50% to 75% (n = 155), and >75% (n = 20) of the segmental surface. The overall quality of perfusion scans was rated as interpretable in all patients. Perfusion scans depicted areas of hyperattenuation within segments of GGO with a significantly higher frequency in group 2 (211 of 212 [99.5%]) than in group 1 (27 of 231 [12%]) (P < .0001). Hyperattenuated areas of vascular origin were observed to match the areas of GGO in surface (203 of 211 [96%]) and contours (208 of 211 [98.6%])., Conclusion: Dual-energy computed tomography can help recognize GGO of vascular origin., (Copyright 2010 AUR. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the performance of a computer-aided detection (CAD) system for diagnosing peripheral acute pulmonary embolism (PE) with a 64-slice multi-detector row computed tomography (CT)., Materials and Methods: Two radiologists investigated the accuracy of a software aimed at detecting peripheral clots (PECAD prototype, version 7; Siemens Medical Systems, Forchheim, Germany) by applying this tool for the analysis of the pulmonary arterial bed of 74 CT angiograms obtained with 64-slice dual-source CT (Definition; Siemens Medical Systems). These cases were retrospectively selected from a database of CT studies performed on the same CT unit, with a similar collimation (64 x 0.6 mm) and similar injection protocols. Patient selection was based on a variety of (1) scanning conditions, namely, nongated (n = 30), electrocardiography-gated (n = 30), and dual-energy CT angiograms (n = 14), and (2) image quality (IQ), namely, scans of excellent IQ (n = 53) and lower IQ due to lower levels of arterial enhancement and/or presence of noise (n = 21). The standard of truth was based on the 2 radiologists' consensus reading and the results of CAD., Results: The software detected 80 of 93 peripheral clots present in the 21 patients (42 segmental and 38 subsegmental clots). The overall sensitivity (95% confidence interval) of the CAD tool was 86% (77%-92%) for detecting peripheral clots, 78% (64.5%-88%) at the segmental level and 97% (85.5%-99.9%) at the subsegmental level. Assuming normal vascular anatomy with 20 segmental and 40 subsegmental arteries, overall specificity and positive and negative predictive values (95% confidence interval) of the software were 91.8% (91%-92.6%), 18.4% (15%-22.4%), and 99.7% (99.5%-99.8%), respectively. A mean of 5.4 false positives was found per patient (total, 354 false positives), mainly linked to the presence of perivascular connective tissue (n = 119; 34%) and perivascular airspace consolidation (n = 97; 27%). The sensitivities (95% confidence interval) for the CAD tool were 91% (69.8%-99.3%) for dual-energy, 87% (59.3%-93.2%) for electrocardiography-gated, and 87% (73.5%-95.3%) for nongated scans (P > 0.05). No significant difference was found in the sensitivity of the CAD software when comparing the scans according to the scanning conditions and image quality., Conclusions: The evaluated CAD software has a good sensitivity in detecting peripheral PE, which is not influenced by the scanning conditions or the overall image quality.

Recent technological advances in multidetector computed tomography (CT) have led to the introduction of dual-source CT, which allows acquisition of CT data at the same energy or at 2 distinct tube voltage settings during a single acquisition. The advantage of the former is improvement of temporal resolution, whereas the latter offers new options for CT imaging, allowing tissue characterization and functional analysis with morphologic evaluation. The most investigated application has been iodine mapping at pulmonary CT angiography. The material decomposition achievable opens up new options for recognizing substances poorly characterized by single-energy CT. Although it is too early to draw definitive conclusions on dual-energy CT applications, this article reviews the results already reported with the first generation of dual-source CT systems.

Numerous respiratory disorders may be responsible for right heart dysfunction, frequently suboptimally assessed in routine clinical practice. Multidetector-row CT systems with fast scanning capabilities can acquire images of the thorax with reduced cardiac motion artifacts, enabling improved evaluation of the heart. Moreover, the introduction of fast rotation speed and dedicated cardiac reconstruction algorithms exploiting the multislice acquisition scheme of the data has opened the possibility of integrating right cardiac functional information into a diagnostic CT scan of the chest, without or with ECG gating.

Purpose: To compare peripheral pulmonary artery image quality at 80 kVp and 140 kVp in the same patients., Materials and Methods: Image quality of third-, fourth- and fifth-order arteries was assessed at 80 kV and 140 kV on 1-mm-thick transverse scans, generated from dual-source computed tomography (CT) acquisitions., Results: The mean level of enhancement was significantly higher at 80 kV compared with 140 kV for the third-, fourth-, and fifth-order arteries (P < 0.0001). Despite a higher noise level at 80 kV (P < 0.0001), the signal-to-noise ratio and contrast-to-noise ratio were significantly higher at 80 kV than at 140 kV at the level of third-, fourth-, and fifth-order arteries (P < 0.0001). The mean vascular attenuation, mean signal-to-noise ratio and contrast-to-noise ratio for peripheral arteries were significantly superior at 80 kV in the 3 body mass index categories (P < 0.005)., Conclusions: Eighty-kilovolt protocols significantly improve the image quality of peripheral pulmonary arteries on CT angiograms of the chest.

The aim of the present study was to describe angiographic findings and embolisation results in smokers with haemoptysis. We retrospectively reviewed the clinical data and angiographic findings from 35 patients with smoking-related bronchopulmonary disease and no associated comorbidity, who were referred for embolisation for mild (n = 6), moderate (n = 14) and severe (n = 15) haemoptysis. Spirometric classification subdivided our population into: 16 patients with chronic bronchitis but no airflow limitation; and 19 patients with chronic obstructive pulmonary disease (COPD) (stage I: n = 12; stage II: n = 5; stage III: n = 2). Bronchoscopy depicted focal submucosal vascular abnormalities in three patients and only endobronchial inflammation in 32 (91%) patients. Bronchial artery angiography revealed moderate (n = 18) or severe (n = 10) hypervascularisation in 28 (80%) patients, and normal vascularisation in seven (20%). No statistically significant difference was observed between the angiographic findings and the severity of COPD, tobacco consumption or the amount of bleeding. Cessation of bleeding was obtained by embolisation in 29 out of the 34 technically successful procedures (85%), requiring surgery in three out of five patients with recurrence. Follow-up (mean duration 7 yrs) demonstrated no recurrence of bleeding in 32 (94%) out of 34 patients and excluded late endobronchial malignancy. Smokers with various stages of COPD severity may suffer from haemoptysis that is efficiently treatable by endovascular treatment.

Purpose: To evaluate, by using electrocardiographically (ECG)-gated multidetector computed tomography (CT), parameters such as right ventricular outflow tract (RVOT) systolic shortening and myocardial thickness and right pulmonary artery (RPA) distensibility, reported to be abnormal at echocardiography and/or magnetic resonance (MR) imaging in patients with pulmonary hypertension (PHT)., Materials and Methods: The institutional review board approved the study and waived informed consent. Forty-five patients, 21 with PHT (group 1; mean pulmonary arterial pressure [PAP], 42 mm Hg) and 24 without (group 2; mean PAP, 16.5 mm Hg), who had undergone thoracic ECG-gated 64-section CT and right heart catheterization as part of their diagnostic work-up were included in this study. Two independent observers measured RPA distensibility and RVOT myocardial thickness, diameter, and cross-sectional area during systole and diastole. Their values were compared in both groups (Mann-Whitney U test). The area under the receiver operating characteristic (ROC) curve and Spearman correlation with mean PAP were also obtained., Results: Interobserver agreement was good for all measurements (R > 0.8) except for systolic RVOT wall thickness. Median values of RPA distensibility, diastolic RVOT wall thickness, and systolic RVOT diameter and cross-sectional area were significantly different between groups 1 and 2. The largest area under the ROC curve was obtained with RPA distensibility (0.951; 95% confidence interval: 0.89, 1) also showing the closest correlation with mean PAP (r = -0.79; P < .0001)., Conclusion: Among all parameters evaluated, RPA distensibility shows the best diagnostic value for PHT and could be useful for risk stratification.

Rationale and Objectives: To investigate the accuracy of dual-energy computed tomography in the depiction of perfusion defects in patients with acute pulmonary embolism (PE)., Materials and Methods: One hundred seventeen consecutive patients with clinical suspicion of acute PE underwent dual-energy multidetector computed tomographic (CT) angiography of the chest with a standard injection protocol. Two radiologists evaluated, by consensus, the presence of endoluminal clots on (1) transverse "diagnostic" scans (contiguous 1-mm-thick averaged images from tubes A and B) and (2) lung perfusion scans., Results: Seventeen patients showed CT features of acute PE, with the depiction of 75 clots within the lobar (n = 15), segmental (n = 43) and subsegmental (n = 17) pulmonary arteries. A total of 17 clots were identified as complete filling defects (ie, obstructive clots), located within segmental (12 of 17) and subsegmental (5 of 17) arteries. Fourteen of the 17 obstructive clots were seen with the concurrent presence of corresponding perfusion defects, whereas cardiac motion and/or contrast-induced artifacts precluded the confident recognition of perfusion abnormalities in the remaining two segments and one subsegment. Four subsegmental perfusion defects were depicted without the visualization of endoluminal thrombi within the corresponding arteries. Perfusion defects were identified beyond five nonobstructive clots., Conclusion: Simultaneous information on the presence of endoluminal thrombus and lung perfusion impairment can be obtained with dual-energy computed tomography.

Among the various imaging modalities available, CT has remained over time the core imaging technique for the evaluation of respiratory disorders. The recent advent of dual-source CT offers innovative approaches to investigate thoracic diseases, based on the use of one or two tubes as well as single or dual energy to scan the entire thorax. Two major options can be used in clinical practice with promising results. Dual source, single-energy scanning allows scanning of the entire thorax with ultra-high temporal resolution which opens the field of integrated cardiothoracic imaging without ECG gating as well as optimized evaluation of pediatric and adult patients with limited ability to cooperate. Dual-source, dual-energy acquisitions represent another very innovative means of investigating respiratory disorders, adding tissue characterization and functional analysis to morphological evaluation. The purpose of this review article is to provide results on preliminary experiences with the above-mentioned scanning conditions with dual-source CT and to envisage potential forthcoming applications in the field of thoracic imaging.

Purpose: To evaluate nongated multidetector computed tomography (CT) in the detection of patent foramen ovale (PFO) and atrial septal aneurysm (ASA) in comparison with transesophageal echocardiography (TEE)., Materials and Methods: The study was approved by the institutional review board, and informed consent was obtained from all patients. One hundred five patients (57 men, 48 women; mean age, 53 years) with a recent stroke underwent TEE and multidetector CT on the same day. After injection of a diluted iodinated contrast material, a series of 2.4-mm-thick transverse images centered on the fossa ovalis were acquired in conjunction with release of the Valsalva maneuver. Two independent radiologists considered PFO present if left atrial enhancement was detected visually before enhancement of the pulmonary veins or if an early peak of left atrial enhancement was found at time-attenuation curve analysis., Results: PFO was detected with 98% specificity (95% confidence interval [CI]: 0.91, 0.99). Overall sensitivity was 55% (95% CI: 0.38, 0.70), ranging from 28% for shunts classified as grade 1 at TEE to 91% for those classified as grade 4 at TEE. Interreader agreement was good (kappa = 0.81). Visual assessment was better than time-attenuation curve analysis, which enabled detection of only 15 of the 40 cases of PFO. Multidetector CT depicted only 22% of cases of ASA. The mean effective radiation dose was 2.3 mSv., Conclusion: Nongated multidetector CT can be used to diagnose high-grade shunts through a PFO, with 91% sensitivity and 98% specificity. Thus, PFO detection, in addition to routine CT evaluation of the lungs, could be indicated in patients with unexplained hypoxemia., ((c) RSNA, 2008.)

The present study prospectively evaluated the diagnostic yield and safety of electromagnetic navigation-guided bronchoscopy biopsy, for small peripheral lung lesions in patients where standard techniques were nondiagnostic. The study was conducted in a tertiary medical centre on 40 consecutive patients considered unsuitable for straightforward surgery or computed tomography (CT)-guided transthoracic needle aspiration biopsy, due to comorbidities. The lung lesion diameter was mean+/-sem 23.5+/-1.5 mm and the depth from the visceral-costal pleura was 14.9+/-2 mm. Navigation was facilitated by an electromagnetic tracking system which could detect a position sensor incorporated into a flexible catheter advanced through a bronchoscope. Information obtained during bronchoscopy was superimposed on previously acquired CT data. Divergence between CT data and data obtained during bronchoscopy was calculated by the system's software as a measure of navigational accuracy. All but one of the target lesions was reached and the overall diagnostic yield was 62.5% (25-40). Diagnostic yield was significantly affected by CT-to-body divergence; yield was 77.2% when estimated divergence was