Radiographic Detection of Post-Traumatic Bone Fractures: Contribution of Artificial Intelligence Software to the Analysis of Senior and Junior Radiologists.

Objectives: The aims of this study were: (a) to evaluate the performance of an artificial intelligence (AI) software package (Boneview Trauma, Gleamer) for the detection of post-traumatic bone fractures in radiography as a standalone; (b) used by two radiologists (osteoarticular senior and junior); and (c) to determine to whom AI would be most helpful. Materials and Methods: Within 14 days of a trauma, 101 consecutive patients underwent radiographic examination of the upper or lower limbs. The definite diagnosis for identifying fractures was: (a) radio-clinical consensus between the radiologist on-call who analyzed the images and the orthopedist (Group 1); (b) Cone Beam computed tomography (CBCT) exploration of the area of interest, in case of doubts or absence of consensus (Group 2). Independently of this diagnosis for both groups, the radiographic images were separately analyzed by two radiologists (osteoarticular senior: SR; junior: JR) prior without, and thereafter with the results of AI. Results: AI performed better than the radiologists in detecting common fractures (Group 1), but not subtle fractures (Group 2). In association with AI, both radiologists increased their overall performances in both groups, whereas this increase was significantly higher for the JR (p < 0.05). Conclusion: AI is reliable for common radiographic fracture identification and is a useful learning tool for radiologists in training. However, the software's overall performance does not exceed that of an osteoarticular senior radiologist, particularly in case of subtle lesions.

Autonomously functioning thyroid nodules present intermediate malignancy risk according to European Thyroid Imaging Reporting and Data System (EU-TIRADS) and yield indeterminate cytology results.

Objectives: The aim was to evaluate the clinical, ultrasound (US) and, when indicated, the cytological and histological characteristics of autonomously functioning thyroid nodules (AFTN) in consecutive patients. Methods: A prospective, single-centre study was conducted between March 2018 and September 2021. In total, 901 consecutive patients were referred for thyroid workup and of 67 AFTN were evaluated. All enrolled patients underwent 99mTcO4 - scintigraphy, additional 123I scintigraphy only in case of normal serum TSH, evaluation of thyroid function, US examination using European Thyroid Imaging and Reporting Data System (EU-TIRADS), and US-guided fine needle aspiration (FNA) cytology when indicated. All indeterminate FNA samples were subjected to DNA sequencing analysis. Results: More than half of the evaluated patients with AFTN were euthyroid; median serum TSH was 0.41 (IQR: 0.03-0.97) mU/L. The median AFTN size measured by US was 27.0 (IQR: 21.1-35.0) mm. 28.4% of AFTN were classified as EU-TIRADS score 3 and 71.6% as EU-TIRADS score 4, indicating that the majority of AFTN had intermediate risk for malignancy according to US. Out of the 47 AFTN subjected to cytological evaluation, 24 (51%) yielded indeterminate FNA results. DNA sequencing revealed pathogenic TSHR and GNAS mutations in 60% of cases. No malignancy was detected at final histology in surgically excised AFTN (n = 12). Conclusions: Of the 67 AFTN evaluated in this study, 50% presented with normal serum TSH, 70% displayed ultrasound features suggesting an intermediate malignancy risk and 50% of the AFTN submitted to cytology yielded indeterminate results. No malignant AFTN was detected.

Is bronchial wall imaging affected by temporal resolution? comparative evaluation at 140 and 75 ms in 90 patients.

PURPOSE: To evaluate the influence of temporal resolution (TR) on cardiogenic artefacts at the level of bronchial walls. MATERIAL AND METHODS: Ninety patients underwent a dual-source, single-energy chest CT examination enabling reconstruction of images with a TR of 75 ms (i.e., optimized TR) (Group 1) and 140 ms (i.e., standard TR) (Group 2). Cardiogenic artefacts were analyzed at the level of eight target bronchi, i.e., right (R) and left (L) B1, B5, B7, and B10 (total number of bronchi examined: n = 720). RESULTS: Cardiogenic artefacts were significantly less frequent and less severe in Group 1 than in Group 2 (p < 0.0001) with the highest scores of discordant ratings for bronchi in close contact with cardiac cavities: RB5 (61/90; 68%); LB5 (66/90; 73%); LB7 (63/90; 70%). In Group 1, 78% (560/720) of bronchi showed no cardiac motion artefacts, whereas 22% of bronchi (160/720) showed artefacts rated as mild (152/160; 95%), moderate (7/160; 4%), and severe (1/160; 1%). In Group 2, 70% of bronchi (503/720) showed artefacts rated as mild (410/503; 82%), moderate (82/503; 16%), and severe (11/503; 2%). CONCLUSION: At 75 ms, most bronchi can be depicted without cardiogenic artefacts. KEY POINTS: • Quantitative CT helps analyze morphologic changes in COPD patients • Cardiogenic artefacts may hamper precise analysis of bronchial dimensions • Temporal resolution of CT acquisitions is an important parameter for bronchial imaging.

Imaging Tumor Response and Tumoral Heterogeneity in Non-Small Cell Lung Cancer Treated With Antiangiogenic Therapy: Comparison of the Prognostic Ability of RECIST 1.1, an Alternate Method (Crabb), and Image Heterogeneity Analysis.

PURPOSE: We aimed to assess computed tomography (CT) intratumoral heterogeneity changes, and compared the prognostic ability of the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, an alternate response method (Crabb), and CT heterogeneity in non-small cell lung cancer treated with chemotherapy with and without bevacizumab. MATERIALS AND METHODS: Forty patients treated with chemotherapy (group C) or chemotherapy and bevacizumab (group BC) underwent contrast-enhanced CT at baseline and after 1, 3, and 6 cycles of chemotherapy. Radiologic response was assessed using RECIST 1.1 and an alternate method. CT heterogeneity analysis generating global and locoregional parameters depicting tumor image spatial intensity characteristics was performed. Heterogeneity parameters between the 2 groups were compared using the Mann-Whitney U test. Associations between heterogeneity parameters and radiologic response with overall survival were assessed using Cox regression. RESULTS: Global and locoregional heterogeneity parameters changed with treatment, with increased tumor heterogeneity in group BC. Entropy [group C: median -0.2% (interquartile range -2.2, 1.7) vs. group BC: 0.7% (-0.7, 3.5), P=0.10] and busyness [-27.7% (-62.2, -5.0) vs. -11.5% (-29.1, 92.4), P=0.10] showed a greater reduction in group C, whereas uniformity [1.9% (-8.0, 9.8) vs. -5.0% (-13.9, 5.6), P=0.10] showed a relative increase after 1 cycle but did not reach statistical significance. Two (9%) and 1 (6%) additional responders were identified using the alternate method compared with RECIST in group C and group BC, respectively. Heterogeneity parameters were not significant prognostic factors. CONCLUSIONS: The alternate response method described by Crabb identified more responders compared with RECIST. However, both criteria and baseline imaging heterogeneity parameters were not prognostic of survival.

Impact of iterative reconstruction on the diagnosis of acute pulmonary embolism (PE) on reduced-dose chest CT angiograms.

PURPOSE: To evaluate the impact of iterative reconstruction on the detectability of clots. METHODS AND MATERIALS: Fifty-three patients were enrolled in a study comparing reduced-dose and full-dose images, available from the same dual-source data set. From each acquisition, three series of images were generated: (1) full-dose images (from both tubes), reconstructed with filtered back projection (FBP) (group 1; standard of reference), (2) reduced-dose images (from tube A only; 60 % dose reduction) reconstructed with FBP (group 2) and iterative reconstruction (SAFIRE) (group 3). RESULTS: In group 1 (mean DLP: 264.6 mGy.cm), (1) PE was diagnosed in 8 patients (15 %) with 82 clots in the central (n = 5), segmental (n = 39) and subsegmental (n = 38) arteries and (2) mean level of noise was 30.56 ± 5.07. In group 2 (mean DLP: 105.8 mGy.cm), a significant increase in noise (44.56 ± 6.24; p < 0.0001) (1) hampered detection of PE in one patient and (2) altered detection of peripheral clots (12 false-negative and 2 false-positive results). In group 3, image noise was not significantly different from that in group 1 (p = 0.1525; effect size: 0.2683), with a similar detection of PE compared to group 1 (p = 1). CONCLUSION: Reconstruction of reduced-dose images (60 % dose reduction) with SAFIRE provided image quality and diagnostic value comparable to those of full-dose FBP images. KEY POINTS: • Iterative reconstruction does not alter the detection of endoluminal clots. • Iterative reconstruction allows dose reduction in the context of acute PE. • Iterative reconstruction allows radiologists to approach the prospects of submilliSievert CT.

Thoracic applications of dual energy.

Computed tomography (CT) is the core imaging modality for the evaluation of thoracic disorders. With the recently developed dual-energy CT (DECT) technique, the clinical utility of CT in the management of pulmonary diseases can be expanded. The most actively investigated principle of dual energy is material decomposition based on attenuation differences at different energy levels. This technique provides two key insights into lung physiology, that is, regional perfusion and ventilation. This functional information is obtained in addition to morphologic information because high-resolution thoracic anatomy is entirely preserved on dual-energy thoracic CT. The second major possibility offered by DECT is virtual monochromatic imaging that represents a new option for standard chest CT in daily routine. In this review, imaging principles and clinical applications of dual-energy thoracic CT are described. Knowledge of the applications of DECT may lead to wider use of this technique in the field of respiratory disorders.

Perfusion CT allows prediction of therapy response in non-small cell lung cancer treated with conventional and anti-angiogenic chemotherapy.

OBJECTIVES: To determine whether CT can depict early perfusion changes in lung cancer treated by anti-angiogenic drugs, allowing prediction of response. METHODS: Patients with non-small cell lung cancer, treated by conventional chemotherapy with (Group 1; n = 17) or without (Group 2; n = 23) anti-vascular endothelial growth factor (anti-VEGF) drug (bevacizumab) underwent CT perfusion before (TIME 0) and after 1 (TIME 1), 3 (TIME 2) and 6 (TIME 3) cycles of chemotherapy. The CT parameters evaluated included: (1) total tumour vascular volume (TVV) and total tumour extravascular flow (TEF); (2) RECIST (Response Evaluation Criteria in Solid Tumours) measurements. Tumour response was also assessed on the basis of the clinicians' overall evaluation. RESULTS: In Group 1, significant reduction in perfusion was identified between baseline and: (1) TIME 1 (TVV, P = 0.0395; TEF, P = 0.015); (2) TIME 2 (TVV, P = 0.0043; TEF, P < 0.0001); (3) TIME 3 (TVV, P = 0.0034; TEF, P = 0.0005) without any significant change in Group 2. In Group 1: (1) the reduction in TVV at TIME 1 was significantly higher in responders versus non-responders at TIME 2 according to RECIST (P = 0.0128) and overall clinicians' evaluation (P = 0.0079); (2) all responders at TIME 2 had a concurrent decrease in TVV and TEF at TIME 1. CONCLUSION: Perfusion CT demonstrates early changes in lung cancer vascularity under anti-angiogenic chemotherapy that may help predict therapeutic response. KEY POINTS: • Perfusion CT has the potential of providing in vivo information about tumour vasculature. • CT depicts early and specific perfusion changes in NSCLC under anti-angiogenic drugs. • Specific therapeutic effects of anti-angiogenic drugs can be detected before tumour shrinkage. • Early perfusion changes can help predict therapeutic response to anti-angiogenic treatment. • Perfusion CT could be a non-invasive tool to monitor anti-angiogenic treatment.

High-pitch, dual-source chest computed tomography angiography without electrocardiographic synchronization: evaluation of cardiac motion artifacts on pulmonary circulation.

PURPOSE: To evaluate the frequency and severity of cardiac motion artifacts on high-pitch, dual-source computed tomography angiograms of the chest. MATERIALS AND METHODS: One hundred consecutive patients underwent a non-electrocardiogram-gated, dual-source chest computed tomography examination with high pitch and high temporal resolution. RESULTS: The mean (±SD) duration of data acquisition was 0.9 (±0.07) seconds and the mean (±SD) heart rate was 78.9 (±15.2) bpm. Cardiac motion artifacts were seen at the level of the pulmonary trunk in 2 patients (2%). Among the 7000 pulmonary arteries analyzed (5 central, 5 lobar, 20 segmental, and 40 subsegmental arteries/patient), pseudofilling defects were depicted at the level of 3 arteries (0.042%), always seen with the concurrent presence of a "double contour" appearance of the vessel walls. Twinkling star artifacts beyond the subsegmental level were seen within 76 segments (76/2000; 3.8% of the examined segments), most commonly in the lingula and left lower lobe. A total of 23 patients (23%) showed at least 1 category of motion artifacts, whereas 77 patients (77%) had motion-free imaging of the pulmonary arteries. CONCLUSIONS: Routine scanning of patients with high pitch and high temporal resolution provides examinations devoid of detrimental cardiac motion artifacts.

Bevacizumab and weekly paclitaxel for non-squamous non small cell lung cancer patients: a retrospective study.

BACKGROUND: Combination of bevacizumab and weekly paclitaxel showed synergitic effects, anti-tumor efficacy and a good toxicity profile for patients with breast cancer but has never been evaluated in non small cell lung cancer (NSCLC). We retrospectively reviewed safety and efficacy of this regimen in metastatic non-squamous NSCLC as fourth-line therapy or beyond. METHODS: Patients were identified from a prospective database. Treatment consisted in paclitaxel 80 mg/m(2) on days 1, 8 and 15 and bevacizumab 15 mg/kg on day 1, every 3 weeks until progression or unacceptable toxicity. RESULTS: Twenty patients were included in this study. Objective response rate at first evaluation was 40% (8/20), confirmed response rate was 15% (3/20) and disease control rate was 75% (15/20). The median progression-free survival and overall survival were 6.4 months (CI95% 4.1-9) and 9.6 months (CI95% 7-19.7). Grade 3-4 adverse events included neutropenia (4/20), onycholysis (2/20) and infection (2/20). One patient died from a bowel perforation and another one died from unknown cause. Prolonged responses were observed in a patient who had received bevacizumab as part of first-line chemotherapy and in another one who harbored an ALK rearrangement. CONCLUSIONS: In our experience, combination of bevacizumab and weekly paclitaxel exhibited acceptable toxicity and had encouraging anti-tumor efficacy as fourth-line treatment or beyond for non-squamous NSCLC patients, supporting further evaluation in larger prospective studies.

Spectral optimization of chest CT angiography with reduced iodine load: experience in 80 patients evaluated with dual-source, dual-energy CT.

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.

Ultrafast imaging of the entire chest without ECG synchronisation or beta-blockade: to what extent can we analyse the coronary arteries?

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.

Dual-energy CT angiography of chronic thromboembolic disease: can it help recognize links between the severity of pulmonary arterial obstruction and perfusion defects?

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.

Assessment of non-small cell lung cancer perfusion: pathologic-CT correlation in 15 patients.

PURPOSE: To assess tumor perfusion with multi-detector row computed tomography (CT) in patients with non-small cell lung carcinoma and to correlate CT findings with pathologic results. MATERIALS AND METHODS: This study was approved by the local Ethics Committee, and all patients provided written informed consent, which included information on the radiation exposure at the CT examinations. Fifteen consecutive patients (mean age, 60.5 years ± 7.7 [standard deviation]), including 14 men (mean age, 59.9 years ± 7.5) and one woman (age, 70 years) with histologically proved non-small cell lung carcinoma were prospectively enrolled. Overall, pathologic-CT correlations were examined in 31 focal tumoral zones. Comparative analysis was performed by using the χ(2) or the Fisher exact test for categoric data. For numeric data, group comparisons were performed by using the Mann-Whitney test. RESULTS: Whole-tumor coverage (mean height, 4.3 cm ± 2.1) was possible in all patients with generation of colored parametric maps of volume transfer constant (K(trans)) and blood volume (BV) by using Patlak analysis. Of the 12 areas that showed high BV, 10 (83%) had a high K(trans); in all 12 cases, the vascular score was high, confirming the presence of numerous tumoral vessels. Nineteen areas showed low BV; when observed concurrently with a high K(trans) (seven of 19), the mean vessel number per area was significantly higher than that seen in areas with low BV and low K(trans) (12 of 19) (P = .038), suggestive of tumoral vessels associated with high interstitial pressure. CONCLUSION: Whole-tumor perfusion analysis is technically feasible with 64-detector row CT, with two patterns suggestive of high tumoral vascularity. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100181/-/DC1.

Imaging the heart-lung relationships during a chest computed tomography examination: is electrocardiographic gating the only option?

Before the advent of fast-scanning multidetector-row computed tomography (CT) technology, thoracic CT studies were exclusively used for the morphologic assessment of thoracic organs, as the concurrent examination of the heart was hampered by image degradation from cardiac motion artifacts. The introduction of fast rotation speed and dedicated cardiac reconstruction algorithms has opened new possibilities for chest imaging, starting with the possibility to integrate cardiac morphologic and functional information into a diagnostic CT scan of the chest. Initiated with 16-slice multidetector-row CT, this concept of integrating morphology and function has been further simplified with 64-slice CT scanners, thus allowing radiologists to provide vital information in the management of patients with a wide variety of acute or chronic respiratory disorders. Because this CT technology offers the possibility of generating high-resolution and motion-free images of the coronary arteries, evaluation of the coronary arteries during CT examinations of the chest should further widen the clinical applications of CT for respiratory patients, keeping in mind that cigarette smoking is a shared risk factor for both impaired lung function and cardiovascular events. The recent advent of high temporal resolution and high pitch modes with dual-source CT simplifies the concept of integrated cardiothoracic imaging, introducing non-electrocardiographic-gated coronary artery imaging. The purpose of this article is to review the successive approaches of these redefined borders of thoracic imaging.

Thoracic applications of dual energy.

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.

Dual-source chest CT angiography with high temporal resolution and high pitch modes: evaluation of image quality in 140 patients.

OBJECTIVE: To evaluate image quality of dual-source computed tomography (CT) angiograms acquired with high temporal resolution and high pitch modes. METHODS: Two groups of 70 consecutive patients underwent chest CT angiography with dual-source, single-energy CT, with an 83-ms temporal resolution and a pitch of 2 (group 1) or a pitch of 3 (group 2). Subjective and objective image quality and the diagnostic value were assessed by two radiologists in consensus. The radiation dose was recorded. RESULTS: The image quality was always diagnostic in both groups, rated as excellent in 97% of group 1 (68/70) and 98.5% of group 2 (69/70) examinations. Although no statistically significant difference in subjective image noise was found between the two groups (p = 0.3055), objective noise was found to be statistically higher in group 2 (p < 0.0001). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were found to be significantly higher in group 1 than in group 2 (p = 0.0014). The acquisition time was significantly shorter in group 2 than in group 1 (p < 0.0001). The dose-length product was significantly lower in group 2 than in group 1 (p < 0.0001). CONCLUSION: High temporal resolution and high pitch modes provided standard CT angiographic examinations of excellent quality for thoracic applications in routine clinical practice.

Evaluation of peripheral pulmonary arteries at 80 kV and at 140 kV: dual-energy computed tomography assessment in 51 patients.

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.

Lung perfusion with dual-energy multidetector-row CT (MDCT): feasibility for the evaluation of acute pulmonary embolism in 117 consecutive patients.

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.

Thoracic applications of dual-source CT technology.

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.

Automated lobar quantification of emphysema in patients with severe COPD.

Automated lobar quantification of emphysema has not yet been evaluated. Unenhanced 64-slice MDCT was performed in 47 patients evaluated before bronchoscopic lung-volume reduction. CT images reconstructed with a standard (B20) and high-frequency (B50) kernel were analyzed using a dedicated prototype software (MevisPULMO) allowing lobar quantification of emphysema extent. Lobar quantification was obtained following (a) a fully automatic delineation of the lobar limits by the software and (b) a semiautomatic delineation with manual correction of the lobar limits when necessary and was compared with the visual scoring of emphysema severity per lobe. No statistically significant difference existed between automated and semiautomated lobar quantification (p > 0.05 in the five lobes), with differences ranging from 0.4 to 3.9%. The agreement between the two methods (intraclass correlation coefficient, ICC) was excellent for left upper lobe (ICC = 0.94), left lower lobe (ICC = 0.98), and right lower lobe (ICC = 0.80). The agreement was good for right upper lobe (ICC = 0.68) and moderate for middle lobe (IC = 0.53). The Bland and Altman plots confirmed these results. A good agreement was observed between the software and visually assessed lobar predominance of emphysema (kappa 0.78; 95% CI 0.64-0.92). Automated and semiautomated lobar quantifications of emphysema are concordant and show good agreement with visual scoring.