Incidence of pulmonary embolism and impact on mortality in patients with malignant melanoma.

PURPOSE: Pulmonary embolism (PE) occurs frequently in patients with malignant melanoma (MM). The aim of this study is to determine the incidence of PE in patients with MM and to assess the clinical characteristics and mortality of MM patients with PE. MATERIAL AND METHODS: Medical records from 381 MM patients who underwent contrast-enhanced computed tomography were evaluated. Imaging parameters including location of PE and measurements of right heart dysfunction and clinical parameters including D-Dimer levels, local and distant tumor stage and time of death were analyzed. RESULTS: PE was found in 23/381 (6%) MM patients, whereby 17/23 (74%) were detected incidentally and only 6/23 (26%) were symptomatic. The presence of PE significantly correlated with elevated D-Dimers (p < 0.001), right ventricular dysfunction (p = 0.04), higher local tumor stage (≥T3) (p = 0.05), presence of visceral (p = 0.02) or cerebral metastases (p = 0.03) and increased mortality (p = 0.05). Further, patients with central PE showed an increased mortality compared to peripheral PE (p = 0.03), but no correlation was found between the localization of PE and the occurrence of clinical symptoms (p = 0.36). CONCLUSION: PE in patients with MM often occurs without clinical symptoms and is indicative for advanced disease and a poorer prognosis.

Dual-Energy CT Vital Iodine Tumor Burden for Response Assessment in Patients With Metastatic GIST Undergoing TKI Therapy: Comparison With Standard CT and FDG PET/CT Criteria.

BACKGROUND. CT-based criteria for assessing the gastrointestinal stromal tumor (GIST) response to tyrosine kinase inhibitor (TKI) therapy are limited in part because tumor attenuation is influenced by treatment-related changes including hemorrhage and calcification. The iodine concentration may be less impacted by such changes. OBJECTIVE. The purpose of this study was to determine whether the dual-energy CT (DECT) vital iodine tumor burden (TB) allows improved differentiation between treatment responders and nonresponders among patients with metastatic GIST who are undergoing TKI therapy compared with established CT and PET/CT criteria. METHODS. An anthropomorphic phantom with spherical inserts mimicking GIST lesions of varying iodine concentrations and having nonenhancing central necrotic cores underwent DECT to determine a threshold iodine concentration. Forty patients (25 women and 15 men; median age, 57 years) who were treated with TKI for metastatic GIST were retrospectively evaluated. Patients underwent baseline and follow-up DECT and FDG PET/CT. Response assessment was performed using RECIST 1.1, modified Choi (mChoi) criteria, vascular tumor burden (VTB) criteria, DECT vital iodine TB criteria, and European Organization for Research and Treatment of Cancer (EORTC) PET criteria. DECT vital iodine TB criteria used the same percentage changes as RECIST 1.1 response categories. Progression-free survival was compared between responders and nonresponders for each response criterion by use of Cox proportional hazard ratios and Harrell C-indexes (i.e., concordance indexes). RESULTS. The phantom experiment identified a threshold of 0.5 mg/mL to differentiate vital from nonvital tissue. With use of the DECT vital iodine TB, median progression-free survival was significantly different between responders and nonresponders (623 vs 104 days; p < .001).. For nonresponders versus responders, the hazard ratio for disease progression for DECT vital iodine TB was 6.9 versus 7.6 for EORTC PET criteria, 3.3 for VTB criteria, 2.3 for RECIST 1.1, and 2.1 for mChoi criteria. The C-index was 0.74 for EORTC PET criteria, 0.73 for DECT vital iodine TB criteria, 0.67 for VTB criteria, 0.61 for RECIST 1.1, and 0.58 for mChoi criteria. The C-index was significantly greater for DECT vital iodine TB criteria than for RECIST 1.1 (p = .02) and mChoi criteria (p = .002), but it was not different from that for VTB and EORTC PET criteria (p > .05). CONCLUSION. DECT vital iodine TB criteria showed performance comparable to that of EORTC PET criteria and outperformed RECIST 1.1 and mChoi criteria for response assessment of metastatic GIST treated with TKI therapy. CLINICAL IMPACT. DECT vital iodine TB could help guide early management decisions in patients receiving TKI therapy.

Incomplete neo-endothelialization of left atrial appendage closure devices is frequent after 6 months: a pilot imaging study.

PURPOSE: To bridge neo-endothelialization (NE) of implanted left atrial appendage closure (LAA/LAAC) devices, dual antiplatelet therapy is prescribed. Cardiac computed tomography angiography (cCTA) has been proposed for the evaluation of interventional LAAC. This prospective longitudinal observational study applied a standardized imaging protocol to detect progression of NE of LAAC devices 6 months after implantation. METHODS: Consecutive cCTA datasets of patients six months after LAAC were acquired and the standardized multi-planar reconstruction LAA occluder view for post-implantation evaluation (LOVE) algorithm was used. Residual flow of contrast agent inside the LAA without a peri-device leak (PDL) was defined as incomplete neo-endothelialization. Absence of residual flow was defined as complete neo-endothelialization. Since PDL allows residual flow in the LAA, irrespective of neoendothelialization, PDL were excluded from this study. Diabetes mellitus, liver disease, body-mass-index, age, device sizes and type will be assessed as predictors for incomplete NE. RESULTS: 53 consecutive patients were recruited for cCTA imaging. 36 (68%) showed no PDL and were included in the study (median age 77 years, 19% female). At median follow-up of 6 months (median 180 days, IQR 178-180), 44% of patients showed complete NE compared to 56% with NE still incomplete. Age, BMI, device type and size as well as prevalence of diabetes mellitus and liver disease did not show significant correlation with the completeness of NE. CONCLUSION: This pilot study showed that neo-endothelialization is still incomplete in a majority of patients at mid-term follow-up of 6 months after successful LAAC therapy. Further investigation on the consequences of incomplete endothelialization is needed to guide antiplatelet therapy schedules.

COPD Imaging on a 3rd Generation Dual-Source CT: Acquisition of Paired Inspiratory-Expiratory Chest Scans at an Overall Reduced Radiation Risk.

As stated by the Fleischner Society, an additional computed tomography (CT) scan in expiration is beneficial in patients with chronic obstructive pulmonary disease (COPD). It was thus the aim of this study to evaluate the radiation risk of a state-of-the-art paired inspiratory-expiratory chest scan compared to inspiration-only examinations. Radiation doses to 28 organs were determined for 824 COPD patients undergoing routine chest examinations at three different CT systems-a conventional multi-slice CT (MSCT), a 2nd generation (2nd-DSCT), and 3rd generation dual-source CT (3rd-DSCT). Patients examined at the 3rd-DSCT received a paired inspiratory-expiratory scan. Organ doses, effective doses, and lifetime attributable cancer risks (LAR) were calculated. All organ and effective doses were significantly lower for the paired inspiratory-expiratory protocol (effective doses: 4.3 ± 1.5 mSv (MSCT), 3.0 ± 1.2 mSv (2nd-DSCT), and 2.0 ± 0.8 mSv (3rd-DSCT)). Accordingly, LAR was lowest for the paired protocol with an estimate of 0.025 % and 0.013% for female and male patients (50 years) respectively. Image quality was not compromised. Paired inspiratory-expiratory scans can be acquired on 3rd-DSCT systems at substantially lower dose and risk levels when compared to inspiration-only scans at conventional CT systems, offering promising prospects for improved COPD diagnosis.

A quantitative CT parameter for the assessment of pulmonary oedema in patients with acute respiratory distress syndrome.

OBJECTIVES: The aim of this study was to establish quantitative CT (qCT) parameters for pathophysiological understanding and clinical use in patients with acute respiratory distress syndrome (ARDS). The most promising parameter is introduced. MATERIALS AND METHODS: 28 intubated patients with ARDS obtained a conventional CT scan in end-expiratory breathhold within the first 48 hours after admission to intensive care unit (ICU). Following manual segmentation, 137 volume- and lung weight-associated qCT parameters were correlated with 71 clinical parameters such as blood gases, applied ventilation pressures, pulse contour cardiac output measurements and established status and prognosis scores (SOFA, SAPS II). RESULTS: Of all examined qCT parameters, excess lung weight (ELW), i.e. the difference between a patient's current lung weight and the virtual lung weight of a healthy person at the same height, displayed the most significant results. ELW correlated significantly with the amount of inflated lung tissue [%] (p<0.0001; r = -0.66) and was closely associated with the amount of extravascular lung water (EVLW) (p<0.0001; r = 0.72). More substantially than the oxygenation index (PaO2/FiO2) or any other clinical parameter it correlated with the patients' mean SOFA- (p<0.0001, r = 0.69) and SAPS II-Score (p = 0.0005, r = 0.62). Patients who did not survive intensive care treatment displayed higher values of ELW in the initial CT scans. CONCLUSIONS: ELW could serve as a non-invasive method to quantify the amount of pulmonary oedema. It might serve as an early radiological marker of severity in patients with ARDS.

Fusion imaging to evaluate the radiographic anatomical relationship between primary tumors and local recurrences in retroperitoneal soft tissue sarcoma.

BACKGROUND: Local recurrence (LR) of retroperitoneal soft tissue sarcoma (RPS) is a common and life-threatening event. The evaluation of the exact anatomical patterns of local recurrence might help to improve local treatment in RPS. METHODS: Of our local database we extracted ten patients with LR of RPS with axial MRI and/or CT datasets of the primary tumor (PT) and the LR. Using the Osirix DICOM viewer Version v.3.9.4 64-bit (Pixmeo, Geneva, Switzerland) we performed a three-step fusion algorithm consisting of: a) 3-point co-registration of the axial datasets depicting the PT and the LR using three abdominal landmarks b) re-orientation of the datasets and c) image fusion. We evaluated the feasibility of this technique with regard to categorizing the localization of LR as within or distant from the PT. RESULTS: Fusion imaging was feasible in seven out of ten patients. In the other three patients anatomical shifting of organs after surgery led to a relevant mismatch of anatomical landmarks and impeded interpretation of the fused images. In five of seven patients with successful fusion imaging, local recurrences were located within the anatomical borders of the primary tumor, in two out of seven patients local recurrences were distant to the primary. CONCLUSIONS: Fusion imaging of primary tumors and local recurrences is feasible in most patients with RPS. Most local recurrences occurred within the anatomical localization of the primary tumor. For further investigations validation of the technique in larger patient cohorts is required.

More holes, more contrast? Comparing an 18-gauge non-fenestrated catheter with a 22-gauge fenestrated catheter for cardiac CT.

OBJECTIVE: To compare the performance of an 18-gauge nonfenestrated catheter (18-NFC) with a 22-gauge fenestrated catheter (22-FC) for cardiac CT angiography (CCTA) in patients with suspected coronary heart disease. SUBJECTS AND METHODS: 74 consecutive patients imaged on a 2nd generation dual-source CT with arterial phase CCTA were included in this retrospective investigation to either an 18-NFC or 22-FC. In comparison to the 18-NFC, the 22-FC has three additional perforations for contrast agent dispersal proximal to the tip. We examined the two groups for differences in their average attenuation in the right and left ventricles (RV, LV) and in the atrium (RA, LA) as well as in the proximal right coronary artery (RCA) and the left main coronary artery (LM). The averages were calculated for both the 18-NFC and 22-FC. RESULTS: Catheters were successfully placed on the first attempt 97% (36/37) for 18-NFC and 95% (35/37) for the 22-FC. The following enhancement levels were measured: 22-FC (in Hounsfield-Units (HU)): RV = 203±29, LV = 523±36, RA = 198±29, LA = 519±38, RCA = 547±26, LM = 562±25; 18-NFC: RV = 146±26, LV = 464±32, RA = 141±24, LA = 438±35, RCA = 501±23, LM = 523±23; RV (p = 0,03), LV (p = 0.12), RA (p = 0.02), LA (p = 0.04), RCA (p = 0.3), LM (p = 0.33). CONCLUSION: No significant differences in attenuation levels as well as in image quality of the coronary arteries were found between NFC and FC. Nevertheless, the 22-gauge FC examinations showed significantly higher attenuation in the left and right atrium as well as the right ventricle. Patients with poor venous access may benefit from a smaller gauge catheter that can deliver sufficiently high flow rates for CCTA.

Correlation of machine learning computed tomography-based fractional flow reserve with instantaneous wave free ratio to detect hemodynamically significant coronary stenosis.

BACKGROUND: Fractional flow reserve based on coronary CT angiography (CT-FFR) is gaining importance for non-invasive hemodynamic assessment of coronary artery disease (CAD). We evaluated the on-site CT-FFR with a machine learning algorithm (CT-FFRML) for the detection of hemodynamically significant coronary artery stenosis in comparison to the invasive reference standard of instantaneous wave free ratio (iFR®). METHODS: This study evaluated patients with CAD who had a clinically indicated coronary computed tomography angiography (cCTA) and underwent invasive coronary angiography (ICA) with iFR®-measurements. Standard cCTA studies were acquired with third-generation dual-source computed tomography and analyzed with on-site prototype CT-FFRML software. RESULTS: We enrolled 40 patients (73% males, mean age 67 ± 12 years) who had iFR®-measurement and CT-FFRML calculation. The mean calculation time of CT-FFRML values was 11 ± 2 min. The CT-FFRML algorithm showed, on per-patient and per-lesion level, respectively, a sensitivity of 92% (95% CI 64-99%) and 87% (95% CI 59-98%), a specificity of 96% (95% CI 81-99%) and 95% (95% CI 84-99%), a positive predictive value of 92% (95% CI 64-99%), and 87% (95% CI 59-98%), and a negative predictive value of 96% (95% CI 81-99%) and 95% (95% CI 84-99%). The area under the receiver operating characteristic curve for CT-FFRML on per-lesion level was 0.97 (95% CI 0.91-1.00). Per lesion, the Pearson's correlation between the CT-FFRML and iFR® showed a strong correlation of r = 0.82 (p < 0.0001; 95% CI 0.715-0.920). CONCLUSION: On-site CT-FFRML correlated well with the invasive reference standard of iFR® and allowed for the non-invasive detection of hemodynamically significant coronary stenosis.

Coronary CT angiography derived plaque markers correlated with invasive instantaneous flow reserve for detecting hemodynamically significant coronary stenoses.

PURPOSE: The study aimed to compare morphological and anatomic plaque markers derived from coronary computed tomography angiography (cCTA) for the detection of lesion specific ischemia with invasive instantaneous wave free ratio (iFR®) as the reference standard. METHODS: In our prospective study, we enrolled patients with suspected coronary artery disease (CAD), who had undergone cCTA, using a low-dose third-generation dual-source CT and invasive coronary angiography (ICA) with iFR® measurement. Various plaque markers were assessed on cCTA. Discriminatory power of these markers for the detection of ischemia-inducing coronary artery disease was evaluated against invasive iFR®. RESULTS: Our study cohort included 39 patients (66.6 ± 12.0 years, 72 % male). Among 54 vessel-specific lesions, 15 lesions (28 %) were characterized as hemodynamically significant by iFR® ≤0.89. The area under the curve (AUC) of lesion length/ minimal luminal diameter4 (LL/MLD4) (0.84) was greater than the AUC of minimal luminal area (MLA) (0.82), MLD (0.81), the degree of luminal diameter stenosis (0.81), corrected coronary opacification (CCO) (0.79), remodeling index (RI) (0.75), and percentage aggregate plaque volume (%APV) (0.72). LL, vessel volume (VV), total plaque volume (TPV), calcified and non-calcified plaque volume (CPV and NCPV) did not reach statistical significance and were unable to discriminate between vessels with and without ischemia-inducing coronary stenosis. CONCLUSION: LL/MLD4, MLA, MLD, the degree of luminal diameter stenosis, CCO, RI, and %APV derived from cCTA can support the detection of hemodynamically significant coronary stenosis as compared with iFR®, with LL/MLD4 showing the greatest discriminatory power.

Determining optimal needle size for decompression of tension pneumothorax in children - a CT-based study.

BACKGROUND: For neonates and children requiring decompression of tension pneumothorax, specific recommendations for the choice of needle type and size are missing. The aim of this retrospective study was to determine optimal length and diameter of needles for decompression of tension pneumothorax in paediatric patients. METHODS: Utilizing computed tomography, we determined optimal length and diameter of needles to enable successful decompression and at the same time minimize risk of injury to intrathoracic structures and the intercostal vessels and nerve. Preexisting computed tomography scans of the chest were reviewed in children aged 0, 5 and 10 years. Chest wall thickness and width of the intercostal space were measured at the 4th intercostal space at the anterior axillary line (AAL) on both sides of the thorax. In each age group, three needles different in bore and length were evaluated regarding sufficient length for decompression and risk of injury to intrathoracic organs and the intercostal vessels and nerve. RESULTS: 197 CT-scans were reviewed, of which 58 were excluded, resulting in a study population of 139 children and 278 measurements. Width of the intercostal space was small at 4th ICS AAL (0 years: 0.44 ± 0.13 cm; 5 years: 0.78 ± 0.22 cm; 10 years: 1.12 ± 0.36 cm). The ratio of decompression failure to risk of injury at 4th ICS AAL was most favourable for a 22G/2.5 cm catheter in infants (Decompression failure: right: 2%, left: 4%, Risk of injury: right: 14%, left: 24%), a 22G/2.5 cm or a 20G/3.2 cm catheter in 5-year-old children (20G/3.2 cm: Decompression failure: right: 2.1%, left: 0%, Risk of injury: right: 2.1%, left: 17%) and a 18G/4.5 cm needle in 10-year-old children (Decompression failure: right: 9.5%, left: 9.5%, Risk of injury: right: 7.1%, left: 11.9%). CONCLUSIONS: In children aged 0, 5 and 10 years presenting with a tension pneumothorax, we recommend 22G/2.5 cm, 20G/3.2 cm and 18G/4.5 cm needles, respectively, for acute decompression.

Chest wall thickness and depth to vital structures in paediatric patients - implications for prehospital needle decompression of tension pneumothorax.

BACKGROUND: Recommendations regarding decompression of tension pneumothorax in small children are scarce and mainly transferred from the adult literature without existing evidence for the paediatric population. This CT-based study evaluates chest wall thickness, width of the intercostal space (ICS) and risk of injury to vital structures by needle decompression in children. METHODS: Chest wall thickness, width of the intercostal space and depth to vital structures were measured and evaluated at 2nd ICS midclavicular (MCL) line and 4th ICS anterior axillary line (AAL) on both sides of the thorax using computed tomography (CT) in 139 children in three different age groups (0, 5, 10 years). RESULTS: Width of the intercostal space was significantly smaller at the 4th ICS compared to the 2nd ICS in all age groups on both sides of the thorax. Chest wall thickness was marginally smaller at the 4th ICS compared to the 2nd ICS in infants and significantly smaller at 4th ICS in children aged 5 years and 10 years. Depth to vital structure for correct angle of needle entry was smaller at the 4th ICS in all age groups on both sides of the thorax. Incorrect angle of needle entry however is accompanied by a higher risk of injury at 2nd ICS. Furthermore, in some children aged 0 and 5 years, the heart or the thymus gland were found directly adjacent to the thoracic wall at 2nd ICS midclavicular line. CONCLUSION: Especially in small children risk of iatrogenic injury to vital structures by needle decompression is considerably high. The 4th ICS AAL offers a smaller chest wall thickness, but the width of the ICS is smaller and the risk of injury to the intercostal vessels and nerve is greater. Deviations from correct angle of entry however are accompanied by higher risk of injury to intrathoracic structures at the 2nd ICS. Furthermore, we found the heart and the thymus gland to be directly adjacent to the thoracic wall at the 2nd ICS MCL in a few children. From our point of view this puncture site can therefore not be recommended for decompression in small children. We therefore recommend 4th ICS AAL as the primary site of choice.

Predicting Pulmonary Function Testing from Quantified Computed Tomography Using Machine Learning Algorithms in Patients with COPD.

INTRODUCTION: Quantitative computed tomography (qCT) is an emergent technique for diagnostics and research in patients with chronic obstructive pulmonary disease (COPD). qCT parameters demonstrate a correlation with pulmonary function tests and symptoms. However, qCT only provides anatomical, not functional, information. We evaluated five distinct, partial-machine learning-based mathematical models to predict lung function parameters from qCT values in comparison with pulmonary function tests. METHODS: 75 patients with diagnosed COPD underwent body plethysmography and a dose-optimized qCT examination on a third-generation, dual-source CT with inspiration and expiration. Delta values (inspiration-expiration) were calculated afterwards. Four parameters were quantified: mean lung density, lung volume low-attenuated volume, and full width at half maximum. Five models were evaluated for best prediction: average prediction, median prediction, k-nearest neighbours (kNN), gradient boosting, and multilayer perceptron. RESULTS: The lowest mean relative error (MRE) was calculated for the kNN model with 16%. Similar low MREs were found for polynomial regression as well as gradient boosting-based prediction. Other models led to higher MREs and thereby worse predictive performance. Beyond the sole MRE, distinct differences in prediction performance, dependent on the initial dataset (expiration, inspiration, delta), were found. CONCLUSION: Different, partially machine learning-based models allow the prediction of lung function values from static qCT parameters within a reasonable margin of error. Therefore, qCT parameters may contain more information than we currently utilize and can potentially augment standard functional lung testing.

Incidence of transient interruption of contrast (TIC) - A retrospective single-centre analysis in CT pulmonary angiography exams acquired during inspiratory breath-hold with the breathing command: "Please inspire gently!"

OBJECTIVES: To assess the occurrence of transient interruption of contrast (TIC) phenomenon in pulmonary computed tomography angiography (CTPA) exams performed in inspiratory breath-hold after patients were told to inspire gently. METHODS: In this retrospective single-centre study, CTPA exams of 225 consecutive patients scanned on a 16-slice CT scanner system were analysed. A-priori to measurements, exams were screened for inadequate pulmonary artery contrast due to incorrect bolus tracking or failure of i.v. contrast administration. Those exams were excluded. Attenuation values in the thoracic aorta and in the pulmonary trunk were assessed in duplicate measurements (M1 and M2) and the aorto-pulmonary density ratio was calculated. An aorto-pulmonary ratio > 1 with still contrast inflow being visible within the superior vena cava was defined as TIC. RESULTS: 3 patients were excluded due to incorrect bolus tracking. Final analysis was performed in 222 patients (mean age 65 ± 19 years, range 18 to 99 years). Mean density in the pulmonary trunk was 275±17 HU, in the aorta 208 ± 15 HU. Mean aorto-pulmonary ratio was 0.81± 0.29. 48 patients (21.6%) had an aorto-pulmonary ratio >1. Correlation of mean aorto-pulmonary ratio and age was: -0.213 (p = 0.001). Age was not significantly different for an aorto-pulmonary ratio >1 vs. ≤1 (p = 0.122). Both in M1 and M2, 33/222 patients presented with absolute HU values of < 200 HU within the pulmonary artery. In M1 measurements, 24 of these 33 patients (72%) fulfilled TIC criteria (M2: 25/33 patients (75%)). CONCLUSIONS: TIC is a common phenomenon in CTPA studies with inspiratory breath-hold commands after patients were told to inspire gently with an incidence of 22% in our retrospective cohort. Occurrence of TIC shows a significant negative correlation with increasing age and disproportionately often occurs in patients with lower absolute contrast density values within their pulmonary arteries.

Relation of left atrial appendage closure devices to topographic neighboring structures using standardized imaging by cardiac computed tomography angiography.

BACKGROUND: Although left atrial appendage (LAA) anatomy and topographic relations are well understood, little is known about the impairment of neighboring structures (NBS) by an implanted left atrial appendage closure (LAAC) device. This prospective longitudinal observational study for the first time describes distances of implanted LAA closure (LAAC) devices to NBS using a standardized imaging protocol of cardiac computed tomography angiography (cCTA). HYPOTHESIS: cCTA imaging is an eligible tool for post-implantation evaluation of LAAC devices and their relation to neighboring structures. METHODS: cCTA data sets of consecutive patients 6 months after successful LAAC were acquired on a third generation dual-source CT system and reconstructed with a slice thickness of 0.5 mm. The standardized multi-planar reconstruction LAA occluder view for post-implantation evaluation (LOVE) algorithm was used to measure the distances to NBS in relation to LAA morphology and implanted LAAC devices. RESULTS: A total of 48 patients (median age 80 years, 25% female) were included. Left upper pulmonary vein and circumflex artery were generally closest to occlusion devices (median 2.9 and 2.8 mm, respectively). AMPLATZER AMULET devices were closer to the mitral valve annulus than WATCHMAN devices (6.6 mm (inter quartile range [IQR] 4.9-8.6) vs 10.9 mm (IQR 7.4-14.0), P = 0.001). Distances to the left upper pulmonary vein were affected by LAA morphology, with cauliflower type having the closest proximity (1.7 mm [IQR 1.0-3.4], P = 0.048). CONCLUSION: A standardized cCTA imaging protocol is an eligible tool to accurately measure distances to NBS. Left upper pulmonary vein and circumflex artery are closest to LAAC devices and could thus be most prone to impairment.

Assessment of peri-device leaks after interventional left atrial appendage closure using standardized imaging by cardiac computed tomography angiography.

Cardiac computed tomography angiography (cCTA) has recently been proposed for evaluation of successful interventional left atrial appendage closure (LAA/LAAC). This prospective longitudinal observational study aims to assess this proposal by applying a standardized imaging protocol to detect and quantify peri-device leaks (PDL) after LAAC. cCTA datasets of consecutive patients 6 months after successful LAAC were acquired on a third generation dual-source computed tomography system and reconstructed with a slice thickness of 0.5 mm. The standardized multi-planar reconstruction LAA occluder view for post-implantation evaluation (LOVE) algorithm was used to assess PDL in relation to LAA morphology and implanted LAAC devices. A total of 49 patients (median age 80 years, 24% female) were included consecutively. Overall PDL rate was 31%. Leak rates among different left atrial appendage morphologies varied largely. Windsock type had the highest incidence of PDL (47%). AMPLATZER™ AMULET™ device type revealed slightly higher PDL rates than WATCHMAN™ type and showed larger leaks. However, no statistical differences were found. PDL can be sized best in LOVE sagittal views, whereas a synopsis of LOVE sagittal, axial and coronal views allows further examination and detection of small leaks. PDL are common after successful interventional LAAC, which can be accurately detected and sized by standardized cCTA imaging protocols.

Association of Serum Lipid Profile With Coronary Computed Tomographic Angiography-derived Morphologic and Functional Quantitative Plaque Markers.

PURPOSE: Recent advances in image quality of coronary computed tomographic angiography (cCTA) have enabled improved characterization of coronary plaques. Thus, we investigated the association between quantitative morphological plaque markers obtained by cCTA and serum lipid levels in patients with suspected or known coronary artery disease. MATERIALS AND METHODS: We retrospectively analyzed data of 119 statin-naive patients (55±14 y, 66% men) who underwent clinically indicated cCTA between January 2013 and February 2017. Patients were subdivided into a plaque and a no-plaque group. Quantitative and morphologic plaque markers, such as segment involvement score, segment stenosis score, remodeling index, napkin-ring sign, total plaque volume, calcified plaque volume, and noncalcified plaque volume (NCPV) and plaque composition, were analyzed using a semiautomated plaque software prototype. Total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein, low-density lipoprotein/high-density lipoprotein ratio, and triglycerides were determine in both groups. RESULTS: Higher age (61±11 y vs. 52±14 y, P<0.0001) and a higher likelihood of male gender (77% vs. 56%, P<0.0001) were observed in the plaque group. Differences in lipid levels were neither observed for differentiation between plaque presence or absence, nor after subcategorization for plaque composition. LDL serum levels >160 mg/dL correlated with higher NCPV compared with patients with LDL between 100 and 160 mg/dL (112 vs. 27 mm, P=0.037). Other markers were comparable between the different groups. CONCLUSION: Statin-naive patients with known or suspected coronary artery disease did not show differences in lipid levels related to plaque composition by cCTA. Patients with plaques tended to be men and were significantly older. High LDL levels correlated with high NCPV.

Singular value-guided similarity filter improves detection of vessels in low-dose dynamic CT angiography: application to DIEP flap studies.

Dynamic CT angiography provides much more information compared to static 3D CT angiography, in several clinical applications. The prolonged exposure, on the other hand, results in higher radiation dose for to the patient. Care should be taken when designing noise reduction algorithms so that temporal profiles and spatial resolution is not significantly compromised. In particular, in deep inferior epigastric perforators (DIEP) flap studies, the temporal enhancement of small abdominal subcutaneous and intramuscular vessels needs to be evaluated from the surgeons to plan breast reconstruction. We propose a new approach to exploit the data redundancy in the temporal direction and successfully reduce noise via singular value decomposition. The similarity of voxels temporal profiles is then measured on the noise-reduced dataset and a spatial smoothing is performed with an additional edge-preserving weight coming from the noise-reduced tMIP. We named our filter the singular value decomposition guided similarity (SVGS) filter, and compared it to the TIPS (time-intensity profile similarity) filtered data and to the highly constrained filtered backprojection (HYPR) processed data. This institutional review board-approved study included 17 DIEP flap clinical cases, that were retrospectively processed with HYPR, TIPS and SVGS and then compared both qualitatively and quantitatively. Contrast-to-noise ratio (CNR) was used for quantitative evaluation, while a blinded subjective evaluation was performed by an experienced radiologist. We reported significantly improved results with the SVGS filter when compared to the other approaches, both in terms of CNR, as well as with the subjective clinical evaluation. The results over 17 clinical cases suggest that a potential dose reduction of a factor of 9 could be achieved, while preserving the same image quality. In conclusion, we developed an efficient algorithm for dynamic CT angiographic data processing, which successfully enables a reduction of spatial and temporal noise, while preserving and enhancing the visualization of small vessels. We demonstrated the clinical usefulness of the SVGS for the DIEP flap application. The proposed algorithm can be employed to significantly improve image quality and diagnostic acceptability at same dose level or alternatively to reduce radiation dose, to which extent needs to be evaluated in future studies.

Finding the right spot: Where to measure airway parameters in patients with COPD.

PURPOSE: The importance of spirometry for management of COPD was reduced in the 2017 revision of the GOLD report. CT derived airway measurements show strong correlations with lung function tests and symptoms. However, these correlations are specific to the airway localization, and currently there is no evidence for the ideal spot. Therefore, the aim of this prospective study was to systematically correlate CT derived airway measurements with extensive lung function testing. METHODS AND MATERIALS: 65 patients with diagnosed COPD underwent body plethysmography, impulse oscillometry and dose optimized qCT examination (Somatom Force, Healthineers, Germany) in inspiration and expiration. Eight airway parameters (e.g. outer diameter, maximal wall thickness) were acquired for both scans in every lobe for the third to fifth generation bronchus and correlated with the lung function tests. RESULTS: The most significant correlations between airway parameters were found for the third generation bronchus of the upper left lobe during expiration (25 out of 48 correlation pairs, mean r = -0.39) and for the third generation bronchus of the upper right lobe during inspiration (9 out of 48 correlation pairs, mean r = -0.25). No significant correlations were for example found for the upper right lobe in expiration. CONCLUSION: Correlations between airway parameters and lung function tests vary widely between lobes, bronchus generations and breathing states. Our work suggests that the third generation bronchus of the upper left lobe in expiration could be the preferred localization for airway quantification in future studies.

Variability and Reproducibility of 3rd-generation dual-source dynamic volume perfusion CT Parameters in Comparison to MR-perfusion Parameters in Rectal Cancer.

To compare in patients with untreated rectal cancer quantitative perfusion parameters calculated from 3rd-generation dual-source dynamic volume perfusion CT (dVPCT) with 3-Tesla-MR-perfusion with regard to data variability and tumour differentiation. In MR-perfusion, plasma flow (PF), plasma volume (PV) and mean transit time (MTT) were assessed in two measurements (M1 and M2) by the same reader. In dVPCT, blood flow (BF), blood volume (BV), MTT and permeability (PERM) were assessed respectively. CT dose values were calculated. 20 patients (60 ± 13 years) were analysed. Intra-individual and intra-reader variability of duplicate MR-perfusion measurements was higher compared to duplicate dVPCT measurements. dVPCT-derived BF, BV and PERM could differentiate between tumour and normal rectal wall (significance level for M1 and M2, respectively, regarding BF: p < 0.0001*/0.0001*; BV: p < 0.0001*/0.0001*; MTT: p = 0.93/0.39; PERM: p < 0.0001*/0.0001*), with MR-perfusion this was true for PF and PV (p-values M1/M2 for PF: p = 0.04*/0.01*; PV: p = 0.002*/0.003*; MTT: p = 0.70/0.27*). Mean effective dose of CT-staging incl. dVPCT was 29 ± 6 mSv (20 ± 5 mSv for dVPCT alone). In conclusion, dVPCT has a lower data variability than MR-perfusion while both dVPCT and MR-perfusion could differentiate tumour tissue from normal rectal wall. With 3rd-generation dual-source CT dVPCT could be included in a standard CT-staging without exceeding national dose reference values.