Elective ascending aortic aneurysm repair outcomes in a nationwide US cohort.

OBJECTIVE: To quantify contemporary outcomes following elective ascending aortic aneurysm repair, to determine risk factors for adverse events and to evaluate difference by institutional surgical volume. METHODS: We included all elective hospitalisations of adult patients with an ascending aortic aneurysm who underwent aneurysm repair in the Nationwide Readmissions Database between 2016 and 2019. The primary outcome was a composite of in-hospital mortality, stroke (ischaemic and non-ischaemic) and myocardial infarction (MI). We identified independent predictor of adverse events and investigated outcomes by institutional volume. RESULTS: Among 12 043 patients (mean 62.8 years of age, 28.0% female), MI, stroke or in-hospital death occurred in 598 (4.9%) patients during the index admission (acute stroke: 2.7%, MI: 0.7%, in-hospital death: 2.0%). The strongest predictors of in-hospital death, stroke or MI were chronic weight loss, pulmonary circulation disorder and concomitant descending aortic surgery. Higher procedural volume was associated with a lower incidence of in-hospital death, stroke or MI (OR comparing the highest with the lowest tertile 0.71, 95% CI 0.57 to 0.87; p=0.001) and in-hospital death (OR 0.51, 95% CI 0.37 to 0.72; p<0.001), but no difference in 30-day readmissions. CONCLUSIONS: The overall rate of in-hospital death, stroke and MI is nearly 5% in patients undergoing elective ascending aortic aneurysm repair. Among several predictors, chronic weight loss is associated with the largest increase in the risk of poor outcomes. Higher hospital volume is associated with a lower in-hospital mortality, highlighting the importance to refer patients to high-volume centres while discussing the risks and benefits of proceeding with repair.

Interhospital Transfer for the Management of Acute Pulmonary Embolism.

BACKGROUND: There are increasing treatment options for the management of acute pulmonary embolism (PE), though many are only available at tertiary care centers. Patients with acute pulmonary embolism with high-risk features are often transferred for consideration of such therapies. There are limited data describing outcomes in patients transferred with acute pulmonary embolism. METHODS: We evaluated patients with acute pulmonary embolism at our tertiary care center from August 2012 through August 2018 and compared clinical characteristics, pulmonary embolism features, management, and outcomes in those transferred for acute pulmonary embolism to those that were not transferred. RESULTS: Of 2050 patients with pulmonary embolism included in the study, 432 (21.1%) were transferred from an outside hospital with a known diagnosis of pulmonary embolism. Patients transferred had a lower rate of malignancy (22.2% vs 33.3%; P < .001) and median Charlson comorbidity index (3 vs 4; P < .001). A higher percentage of patients transferred were classified as intermediate- or high-risk pulmonary embolism (62.5% vs 43.0%; P <.001) and more frequently received advanced therapy beyond anticoagulation alone (12.5% vs 3.2%, P < .001). Overall survival to discharge was similar between groups, though definite pulmonary embolism-related mortality was higher in the transferred group (38.5% vs 9.4%, P = .004). CONCLUSION: More than 1 in 5 patients treated for acute pulmonary embolism at a tertiary care center were transferred from an outside facility. Transferred patients had higher risk pulmonary embolism features, more often received advanced therapy, and had higher definite pulmonary embolism-related mortality. There are opportunities to further optimize outcomes of patients transferred for management of acute pulmonary embolism.

Health Care Utilization Following Inpatient Femoropopliteal Revascularization With Drug-Coated Balloon Angioplasty: A Nationwide Cohort Analysis.

PURPOSE: To examine nationwide variations in inpatient use of drug-coated balloons (DCBs) for treating femoropopliteal segment occlusive disease and whether DCBs are associated with reduced early out-of-hospital health care utilization. MATERIALS AND METHODS: The study included 24,022 patients who survived hospitalization for femoropopliteal revascularization using DCB angioplasty (n=7850) or uncoated balloon angioplasty (n=16,172) in the 2016-2017 Nationwide Readmissions Database. Differences in patient, hospitalization, and institutional characteristics were compared between treatment strategies. Adjusted logistic regression models were used to examine differences in 6-month rates of readmission, amputation, and repeat intervention. Results are presented as the odds ratio (OR) and 95% confidence interval (CI). RESULTS: Patients treated with DCBs had a higher prevalence of chronic limb-threatening ischemia, diabetes, hypertension, and tobacco use. Revascularization with a DCB was associated with shorter hospitalizations, lower median hospitalization costs, and fewer inpatient lower extremity amputations. Readmissions at 6 months were decreased in patients treated with DCBs compared with uncoated balloon angioplasty (OR 0.90, 95% CI 0.83 to 0.98, p=0.014). The most common reasons for readmission were complications related to procedures (15.4%) and diabetes (15.4%). Compared to patients treated with DCBs, patients treated with uncoated balloon angioplasty were more often readmitted with early procedure-related complications (13.3% vs 17.5%). There were no between-group differences in readmission for sepsis, myocardial infarction, or congestive heart failure. CONCLUSION: DCBs are less often used compared to uncoated balloons during inpatient femoropopliteal procedures. While DCB utilization is associated with more severe comorbidities and advanced peripheral artery disease, readmission rates are decreased through the first 6 months.

Circadian rhythm in critically ill patients: Insights from the eICU Database.

Objective: To investigate the circadian variation among critically ill patients and its association with clinical characteristics and survival to hospital discharge in a large population of patients in the intensive care unit (ICU). Methods: Circadian variation was analyzed by fitting cosinor models to hourly blood pressure (BP) measurements in patients of the eICU Collaborative Research Database with an ICU length of stay of at least 3 days. We calculated the amplitude of the 24-hour circadian rhythm and time of the day when BP peaked. We determined the association between amplitude and time of peak BP and severity of illness, medications, mechanical intubation, and survival to hospital discharge. Results: Among 23,355 patients (mean age 65 years, 55% male), the mean amplitude of the 24-hour rhythm was 4.5 ± 3.1 mm Hg. Higher APACHE-IV scores, sepsis, organ dysfunction, and mechanical ventilation were associated with a lower amplitude and a shifted circadian rhythm (P < .05 for all). The timing of the BP peak was associated with in-hospital mortality (P < .001). Higher BP amplitude was associated with shorter ICU (2 mm Hg amplitude: 7.0 days, 8 mm Hg amplitude: 6.7 days) and hospital (2 mm Hg amplitude: 11.8 days, 8 mm Hg amplitude: 11.3 days) lengths of stay and lower in-hospital mortality (2 mm Hg amplitude: 18.2%, 8 mm Hg amplitude: 15.2%) (P < .001 for all). Conclusion: The 24-hour rhythm is dampened and phase-shifted in sicker patients and those on mechanical ventilation, vasopressors, or inotropes. Dampening and phase shifting are associated with a longer length of stay and higher in-hospital mortality.

Sex differences in presentation, management, and outcomes among patients hospitalized with acute pulmonary embolism.

While the presence of gender disparities in cardiovascular disease have been described, there is a paucity of data regarding the impact of sex in acute pulmonary embolism (PE). We identified all patients admitted to a tertiary care hospital with acute PE between August 1, 2012 through July 1, 2018. We stratified the presenting characteristics, management, and outcomes between women and men. Of the 2031 patients admitted with acute PE, 1081 (53.2%) were women. Women were more likely to present with dyspnea (59.8% vs 52.0%, p < 0.001) and less likely to present with hemoptysis (1.9% vs 4.0%, p = 0.01). Women were older (63.8 ± 17.4 years vs 62.3 ± 15.0 years, p = 0.04), but had lower rates of myocardial infarction, liver disease, smoking history, and prior DVT. PE severity was similar between women and men (massive: 4.9% vs 3.6%; submassive: 43.9% vs 41.8%; p = 0.19), yet women were more likely to present with normal right ventricular size on a surface echocardiogram (63.2% vs 54.8%, p = 0.01). In unadjusted analyses, women were less likely to survive to discharge (92.4% vs 94.7%, p = 0.04), but after adjustment, there was no sex-based survival difference. There were no sex differences in the PE-related diagnostic studies performed, use of advanced therapies, or short-term outcomes, before and after adjustment (p > 0.05 for all). In this large PE cohort from a tertiary care institution, women had different comorbidity profiles and PE presentations compared with men. Despite these differences, there were no sex disparities in PE management or outcomes.

Pregnancy-associated arterial dissections: a nationwide cohort study.

AIMS: Pregnancy is a known risk factor for arterial dissection, which can result in significant morbidity and mortality in the peripartum period. However, little is known about the risk factors, timing, distribution, and outcomes of arterial dissections associated with pregnancy. METHODS AND RESULTS: We included all women ≥12 years of age with hospitalizations associated with pregnancy and/or delivery in the Nationwide Readmissions Database between 2010 and 2015. The primary outcome was any dissection during pregnancy, delivery, or the postpartum period (42-days post-delivery). Secondary outcomes included timing of dissection, location of dissection, and in-hospital mortality. Among 18 151  897 pregnant patients, 993 (0.005%) patients were diagnosed with a pregnancy-related dissection. Risk factors included older age (32.8 vs. 28.0 years), multiple gestation (3.6% vs. 1.9%), gestational diabetes (14.3% vs. 0.2%), gestational hypertension (6.0% vs. 0.6%), and pre-eclampsia/eclampsia (2.7% vs. 0.4%), in addition to traditional cardiovascular risk factors. Of the 993 patients with dissection, 150 (15.1%) dissections occurred in the antepartum period, 232 (23.4%) were diagnosed during the admission for delivery, and 611 (61.5%) were diagnosed in the postpartum period. The most common locations for dissections were coronary (38.2%), vertebral (22.9%), aortic (19.8%), and carotid (19.5%). In-hospital mortality was 3.7% among pregnant patients with a dissection vs. <0.001% in patients without a dissection. Deaths were isolated to patients with an aortic (8.6%), coronary (4.2%), or supra-aortic (<2.5%) dissection. CONCLUSION: Arterial dissections occurred in 5.5/100 000 hospitalized pregnant or postpartum women, most frequently in the postpartum period, and were associated with high mortality risk. The coronary arteries were most commonly involved. Pregnancy-related dissections were associated with traditional risk factors, as well as pregnancy-specific conditions.

Changes in Care for Acute Pulmonary Embolism Through A Multidisciplinary Pulmonary Embolism Response Team.

BACKGROUND: Optimal management of acute pulmonary embolism requires expertise offered by multiple subspecialties. As such, pulmonary embolism response teams (PERTs) have increased in prevalence, but the institutional consequences of a PERT are unclear. METHODS: We compared all patients that presented to our institution with an acute pulmonary embolism in the 3 years prior to and 3 years after the formation of our PERT. The primary outcome was in-hospital pulmonary embolism-related mortality before and after the formation of the PERT. Sub-analyses were performed among patients with elevated-risk pulmonary embolism. RESULTS: Between August 2012 and August 2018, 2042 patients were hospitalized at our institution with acute pulmonary embolism, 884 (41.3%) pre-PERT implementation and 1158 (56.7%) post-PERT implementation, of which 165 (14.2%) were evaluated by the PERT. There was no difference in pulmonary embolism-related mortality between the two time periods (2.6% pre-PERT implementation vs 2.9% post-PERT implementation, P = .89). There was increased risk stratification assessment by measurement of cardiac biomarkers and echocardiograms post-PERT implementation. Overall utilization of advanced therapy was similar between groups (5.4% pre-PERT implementation vs 5.4% post-PERT implementation, P = 1.0), with decreased use of systemic thrombolysis (3.8% pre-PERT implementation vs 2.1% post-PERT implementation, P = 0.02) and increased catheter-directed therapy (1.3% pre-PERT implementation vs 3.3% post-PERT implementation, P = 0.05) post-PERT implementation. Inferior vena cava filter use decreased after PERT implementation (10.7% pre-PERT implementation vs 6.9% post-PERT implementation, P = 0.002). Findings were similar when analyzing elevated-risk patients. CONCLUSION: Pulmonary embolism response teams may increase risk stratification assessment and alter application of advanced therapies, but a mortality benefit was not identified.

Utilization and Outcomes of Thrombolytic Therapy for Acute Pulmonary Embolism: A Nationwide Cohort Study.

BACKGROUND: There are increased options to deliver thrombolytic treatment for acute, high-risk pulmonary embolism (PE). The goals of this study were to examine practice patterns of systemic thrombolysis and catheter-directed thrombolysis (CDT) and to compare outcomes following CDT with ultrasound facilitation (CDT-ultrasound) and CDT alone. METHODS: The study analyzed adults aged > 18 years with hospitalizations associated with acute PE and thrombolysis in the 2016 Nationwide Readmissions Database. The study identified characteristics associated with the use of systemic thrombolysis and CDT. Comparisons of CDT-ultrasound vs CDT alone were then made by evaluating in-hospital events and readmissions. The primary outcomes were in-hospital mortality and 30-day readmission rates. RESULTS: Among 5,436 hospitalizations, systemic thrombolysis was used more often (n = 3,376; 62.1%) than CDT (n = 2,060; 37.9%). Compared with CDT, systemic thrombolysis was used more frequently in patients with higher rates of vasopressor use (4.3% vs 1.0%), shock (15.8% vs. 6.9%), cardiac arrest (12.7% vs 3.4%), and mechanical ventilation (19.0% vs 5.9%). Among patients who underwent CDT, 417 (20.2%) received CDT-ultrasound, and 1,643 (79.8%) received CDT alone. Rates of bleeding events, vasopressor use, and mechanical ventilation were similar between therapeutic strategies. Following adjustment, in-hospital mortality (OR, 1.19; 95% CI, 0.63-2.26; P = .59) and 30-day readmission rates (OR, 0.75; 95% CI, 0.47-1.22; P = .25) were not significantly different between CDT-ultrasound and CDT alone. CONCLUSIONS: Systemic thrombolysis is used more often than CDT in patients with acute PE, in particular among those with a greater prevalence of high-risk features. Among patients treated with CDT, there were no differences in events between CDT-ultrasound and CDT alone.

Three-Dimensional High-Resolution Black-Blood Magnetic Resonance Imaging for Detection of Arteritic Anterior Ischemic Optic Neuropathy in Patients With Giant Cell Arteritis.

OBJECTIVES: Arteritic anterior ischemic optic neuropathy (A-AION) caused by inflammatory occlusion of the posterior ciliary arteries is the most common reason for irreversible vision loss in patients with giant cell arteritis. Atypical clinical presentation and negative funduscopy can delay systemic high-dose corticosteroid therapy to prevent impending permanent blindness and involvement of the contralateral eye.The purpose of this study was to assess the diagnostic accuracy of 3-dimensional (3D) high-resolution T1-weighted black-blood magnetic resonance imaging (T1-BB-MRI) for the detection of posterior ciliary artery involvement in patients with giant cell arteritis and funduscopic A-AION. MATERIALS AND METHODS: After institutional review board approval and informed consent, 27 patients with suspected giant cell arteritis and vision disturbances were included in this monocentric prospective cohort study. Giant cell arteritis was diagnosed in 18 patients according to the diagnostic reference standard (6 men, 73.8 [69.0-78.0] years); 14 of those were positive for A-AION. Precontrast and postcontrast 3D T1-BB-MRI was performed in all 27 patients. Two radiologists separately assessed image quality and local fat suppression (4-point scale), visual contrast enhancement (3-point scale), and diagnostic confidence (5-point scale) regarding arteritic posterior ciliary artery involvement. Magnetic resonance imaging findings were assessed in comparison to funduscopy. Statistical analysis included accuracy parameters and interrater agreement. RESULTS: Sensitivity of 3D T1-BB-MRI was 92.9% (95% confidence interval, 66.1%-99.8%) and specificity was 92.3% (95% confidence interval, 64.0%-99.8%) for detection of A-AION-positive patients. Image quality and local fat suppression were assessed with 3.2 ± 0.8 (median 3) and 3.8 ± 0.5 (median 4). Visual contrast enhancement with 2.3 ± 0.8 (median 3) and diagnostic confidence was rated at 4.7 ± 0.5 (median 5). Interrater agreement was high (κ = 0.85, P < 0.001). Three-dimensional T1-BB-MRI displayed bilateral findings in 50% of the cases, whereas only unilateral A-AION was detected in funduscopy as a possible indication for the contralateral eye at risk. CONCLUSIONS: Three-dimensional T1-BB-MRI allows accurate detection of arteritic posterior ciliary artery involvement in patients with A-AION. Further, 3D T1-BB-MRI seems to display arteritic involvement of the posterior ciliary arteries earlier than funduscopy and might, therefore, display "vision-at-risk" in patients with visual impairment and suspected giant cell arteritis but unremarkable funduscopy.

Prospective association between handgrip strength and cardiac structure and function in UK adults.

BACKGROUND: Handgrip strength, a measure of muscular fitness, is associated with cardiovascular (CV) events and CV mortality but its association with cardiac structure and function is unknown. The goal of this study was to determine if handgrip strength is associated with changes in cardiac structure and function in UK adults. METHODS AND RESULTS: Left ventricular (LV) ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), mass (M), and mass-to-volume ratio (MVR) were measured in a sample of 4,654 participants of the UK Biobank Study 6.3 ± 1 years after baseline using cardiovascular magnetic resonance (CMR). Handgrip strength was measured at baseline and at the imaging follow-up examination. We determined the association between handgrip strength at baseline as well as its change over time and each of the cardiac outcome parameters. After adjustment, higher level of handgrip strength at baseline was associated with higher LVEDV (difference per SD increase in handgrip strength: 1.3ml, 95% CI 0.1-2.4; p = 0.034), higher LVSV (1.0ml, 0.3-1.8; p = 0.006), lower LVM (-1.0g, -1.8 --0.3; p = 0.007), and lower LVMVR (-0.013g/ml, -0.018 --0.007; p<0.001). The association between handgrip strength and LVEDV and LVSV was strongest among younger individuals, while the association with LVM and LVMVR was strongest among older individuals. CONCLUSIONS: Better handgrip strength was associated with cardiac structure and function in a pattern indicative of less cardiac hypertrophy and remodeling. These characteristics are known to be associated with a lower risk of cardiovascular events.

Multiple Sclerosis: Improved Detection of Active Cerebral Lesions With 3-Dimensional T1 Black-Blood Magnetic Resonance Imaging Compared With Conventional 3-Dimensional T1 GRE Imaging.

OBJECTIVES: The aim of this study was to assess the diagnostic accuracy of a modified high-resolution whole-brain three-dimensional T1-weighted black-blood sequence (T1-weighted modified volumetric isotropic turbo spin echo acquisition [T1-mVISTA]) in comparison to a standard three-dimensional T1-weighted magnetization-prepared rapid gradient echo (MP-RAGE) sequence for detection of contrast-enhancing cerebral lesions in patients with relapsing-remitting multiple sclerosis (MS). MATERIALS AND METHODS: After institutional review board approval and informed consent, 22 patients (8 men; aged 31.0 ± 9.2 years) with relapsing-remitting MS were included in this monocentric prospective cohort study.Contrast-enhanced T1-mVISTA and MP-RAGE, both with 0.8 mm resolution, were performed in all patients. In a substudy of 12 patients, T1-mVISTA was compared with a T1-mVISTA with 1.0 mm resolution (T1-mVISTA_1.0). Reference lesions were defined by an experienced neuroradiologist using all available sequences and served as the criterion standard. T1-mVISTA, T1-mVISTA_1.0, and MP-RAGE sequences were read in random order 4 weeks apart. Image quality, visual contrast enhancement, contrast-to-noise-ratio (CNR), diagnostic confidence, and lesion size were assessed and compared by Wilcoxon and Mann-Whitney U tests. RESULTS: Eleven of 22 patients displayed contrast-enhancing lesions. Visual contrast enhancement, CNR, and diagnostic confidence of contrast-enhancing MS lesions were significantly increased in T1-mVISTA compared with MP-RAGE (P < 0.001). Significantly more contrast-enhancing lesions were detected with T1-mVISTA than with MP-RAGE (71 vs 39, respectively; P < 0.001). With MP-RAGE, 25.6% of lesions were missed in the initial reading, whereas only 4.2% of lesions were missed with T1-mVISTA. Increase of the voxel volume from 0.8 mm to 1.0 mm isotropic in T1-mVISTA_1.0 did not affect the detectability of lesions, whereas scan time was decreased from 4:43 to 1:55 minutes. CONCLUSIONS: Three-dimensional T1-mVISTA improves the detection rates of contrast-enhancing cerebral MS lesions compared with conventional 3D MP-RAGE sequences by increasing CNR of lesions and might, therefore, be useful in patient management.

Automatic Lung-RADS™ classification with a natural language processing system.

BACKGROUND: Our aim was to train a natural language processing (NLP) algorithm to capture imaging characteristics of lung nodules reported in a structured CT report and suggest the applicable Lung-RADS™ (LR) category. METHODS: Our study included structured, clinical reports of consecutive CT lung screening (CTLS) exams performed from 08/2014 to 08/2015 at an ACR accredited Lung Cancer Screening Center. All patients screened were at high-risk for lung cancer according to the NCCN Guidelines®. All exams were interpreted by one of three radiologists credentialed to read CTLS exams using LR using a standard reporting template. Training and test sets consisted of consecutive exams. Lung screening exams were divided into two groups: three training sets (500, 120, and 383 reports each) and one final evaluation set (498 reports). NLP algorithm results were compared with the gold standard of LR category assigned by the radiologist. RESULTS: The sensitivity/specificity of the NLP algorithm to correctly assign LR categories for suspicious nodules (LR 4) and positive nodules (LR 3/4) were 74.1%/98.6% and 75.0%/98.8% respectively. The majority of mismatches occurred in cases where pulmonary findings were present not currently addressed by LR. Misclassifications also resulted from the failure to identify exams as follow-up and the failure to completely characterize part-solid nodules. In a sub-group analysis among structured reports with standardized language, the sensitivity and specificity to detect LR 4 nodules were 87.0% and 99.5%, respectively. CONCLUSIONS: An NLP system can accurately suggest the appropriate LR category from CTLS exam findings when standardized reporting is used.

Cost-Effectiveness of Endovascular Stroke Therapy: A Patient Subgroup Analysis From a US Healthcare Perspective.

BACKGROUND AND PURPOSE: Endovascular therapy in addition to standard care (EVT+SC) has been demonstrated to be more effective than SC in acute ischemic large vessel occlusion stroke. Our aim was to determine the cost-effectiveness of EVT+SC depending on patients' initial National Institutes of Health Stroke Scale (NIHSS) score, time from symptom onset, Alberta Stroke Program Early CT Score (ASPECTS), and occlusion location. METHODS: A decision model based on Markov simulations estimated lifetime costs and quality-adjusted life years (QALYs) associated with both strategies applied in a US setting. Model input parameters were obtained from the literature, including recently pooled outcome data of 5 randomized controlled trials (ESCAPE [Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke], EXTEND-IA [Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial], MR CLEAN [Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands], REVASCAT [Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within 8 Hours of Symptom Onset], and SWIFT PRIME [Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment]). Probabilistic sensitivity analysis was performed to estimate uncertainty of the model results. Net monetary benefits, incremental costs, incremental effectiveness, and incremental cost-effectiveness ratios were derived from the probabilistic sensitivity analysis. The willingness-to-pay was set to $50 000/QALY. RESULTS: Overall, EVT+SC was cost-effective compared with SC (incremental cost: $4938, incremental effectiveness: 1.59 QALYs, and incremental cost-effectiveness ratio: $3110/QALY) in 100% of simulations. In all patient subgroups, EVT+SC led to gained QALYs (range: 0.47-2.12), and mean incremental cost-effectiveness ratios were considered cost-effective. However, subgroups with ASPECTS ≤5 or with M2 occlusions showed considerably higher incremental cost-effectiveness ratios ($14 273/QALY and $28 812/QALY, respectively) and only reached suboptimal acceptability in the probabilistic sensitivity analysis (75.5% and 59.4%, respectively). All other subgroups had acceptability rates of 90% to 100%. CONCLUSIONS: EVT+SC is cost-effective in most subgroups. In patients with ASPECTS ≤5 or with M2 occlusions, cost-effectiveness remains uncertain based on current data.

Classification of arterial and venous cerebral vasculature based on wavelet postprocessing of CT perfusion data.

PURPOSE: The purpose of this study was to propose and evaluate a new wavelet-based technique for classification of arterial and venous vessels using time-resolved cerebral CT perfusion data sets. METHODS: Fourteen consecutive patients (mean age 73 yr, range 17-97) with suspected stroke but no pathology in follow-up MRI were included. A CT perfusion scan with 32 dynamic phases was performed during intravenous bolus contrast-agent application. After rigid-body motion correction, a Paul wavelet (order 1) was used to calculate voxelwise the wavelet power spectrum (WPS) of each attenuation-time course. The angiographic intensity A was defined as the maximum of the WPS, located at the coordinates T (time axis) and W (scale/width axis) within the WPS. Using these three parameters (A, T, W) separately as well as combined by (1) Fisher's linear discriminant analysis (FLDA), (2) logistic regression (LogR) analysis, or (3) support vector machine (SVM) analysis, their potential to classify 18 different arterial and venous vessel segments per subject was evaluated. RESULTS: The best vessel classification was obtained using all three parameters A and T and W [area under the curve (AUC): 0.953 with FLDA and 0.957 with LogR or SVM]. In direct comparison, the wavelet-derived parameters provided performance at least equal to conventional attenuation-time-course parameters. The maximum AUC obtained from the proposed wavelet parameters was slightly (although not statistically significantly) higher than the maximum AUC (0.945) obtained from the conventional parameters. CONCLUSIONS: A new method to classify arterial and venous cerebral vessels with high statistical accuracy was introduced based on the time-domain wavelet transform of dynamic CT perfusion data in combination with linear or nonlinear multidimensional classification techniques.

Early CT perfusion mismatch in acute stroke is not time-dependent but relies on collateralization grade.

INTRODUCTION: Factors that determine the extent of the penumbra in the initial diagnostic workup using whole brain CT Perfusion (WB-CTP) remain unclear. The purpose of the current study was to determine a possible dependency of the initial mismatch size between cerebral blood flow (CBF) and cerebral blood volume (CBV) from time after symptom onset, leptomeningeal collateralization, and occlusion localization in acute middle cerebral artery (MCA) infarctions. METHODS: Out of an existing cohort of 992 consecutive patients receiving multiparametric CT scans including WB-CTP due to suspected stroke, we included patients who had (1) a witnessed time of symptom onset, (2) an infarction of the MCA territory as documented by follow-up imaging, and (3) an initial CBF volume of >10 ml. CBF and CBV lesion sizes, collateralization grade, and the site of occlusion were determined. RESULTS: We included 103 patients. Univariate analysis showed that time from symptom onset (168 +/- 91.2 min) did not correlate with relative or absolute mismatch volumes (p = 0.458 and p = 0.921). Higher collateralization gradings were associated with small absolute mismatch volumes (p = 0.004 and p < 0.001). Internal carotid artery (ICA) occlusions were associated with large absolute mismatch volumes (p = 0.004). Multivariate analysis confirmed that ICA occlusion was associated with large absolute mismatch volumes (p = 0.005), and high collateral grade was associated with small absolute mismatch volumes (p = 0.017). CONCLUSIONS: There is no significant correlation between initial CTP mismatch and time after symptom onset. Predictors of mismatch size include the extent of the collaterals and a proximal location of the occlusion.

Different Imaging Strategies in Patients With Possible Basilar Artery Occlusion: Cost-Effectiveness Analysis.

BACKGROUND AND PURPOSE: This study evaluated the cost-effectiveness of different noninvasive imaging strategies in patients with possible basilar artery occlusion. METHODS: A Markov decision analytic model was used to evaluate long-term outcomes resulting from strategies using computed tomographic angiography (CTA), magnetic resonance imaging, nonenhanced CT, or duplex ultrasound with intravenous (IV) thrombolysis being administered after positive findings. The analysis was performed from the societal perspective based on US recommendations. Input parameters were derived from the literature. Costs were obtained from United States costing sources and published literature. Outcomes were lifetime costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios, and net monetary benefits, with a willingness-to-pay threshold of $80,000 per QALY. The strategy with the highest net monetary benefit was considered the most cost-effective. Extensive deterministic and probabilistic sensitivity analyses were performed to explore the effect of varying parameter values. RESULTS: In the reference case analysis, CTA dominated all other imaging strategies. CTA yielded 0.02 QALYs more than magnetic resonance imaging and 0.04 QALYs more than duplex ultrasound followed by CTA. At a willingness-to-pay threshold of $80,000 per QALY, CTA yielded the highest net monetary benefits. The probability that CTA is cost-effective was 96% at a willingness-to-pay threshold of $80,000/QALY. Sensitivity analyses showed that duplex ultrasound was cost-effective only for a prior probability of ≤0.02 and that these results were only minimally influenced by duplex ultrasound sensitivity and specificity. Nonenhanced CT and magnetic resonance imaging never became the most cost-effective strategy. CONCLUSIONS: Our results suggest that CTA in patients with possible basilar artery occlusion is cost-effective.

Validation of a method to differentiate arterial and venous vessels in CT perfusion data using linear combinations of quantitative time-density curve characteristics.

OBJECTIVES: We aimed to develop and evaluate a new method that reliably differentiates between cerebral arteries and veins using voxel-wise CT-perfusion-derived parameters. MATERIALS AND METHODS: Fourteen consecutive patients with suspected stroke but without pathological findings were examined on a multi-detector CT system: 32 dynamic phases (∆t = 1.5 s) during application of 35 mL iomeprol-350 were acquired at 80 kV/200mAs. Three hemodynamic parameters were calculated for 18 arterial and venous vessel segments: A (maximum of the time-density-curve), T (time-to-peak), and W (full-width-at-half-maximum). Using receiver operator characteristic (ROC) curve analysis and Fisher's linear discriminant analysis (FLDA), the performance of every classifier (A, T, W) and of all linear combinations for the differentiation of arterial and venous vessels was determined. RESULTS: A maximum area under the ROC-curve (AUC) of 0.945 (accuracy = 86.8%) was obtained using the FLDA combination of A&T or the triplet FLDA of A&T&W for the classification of venous and arterial vessels. The best single parameter was T with an AUC of 0.871 (accuracy = 79.0%), which performed significantly worse than the combination A&T (p < 0.001). CONCLUSIONS: Arteries and veins can be accurately differentiated based on dynamic CT perfusion data using the maximum of the time-density curve, its time-to-peak, its width, and FLDA combinations of these parameters, which yield accuracies up to 87%. KEY POINTS: • For classification of cerebral vasculature, time-to-peak has the best single-parameter accuracy. • Fisher's linear discriminant analysis improves the performance of the individual classifiers. • Combining signal maximum and time-to-peak parameters significantly increased the classifying potential. • Pre-processing of time-density-curves by Gaussian filtering or fitting can improve diagnostic accuracy.

Wavelet-based calculation of cerebral angiographic data from time-resolved CT perfusion acquisitions.

OBJECTIVES: To evaluate a new approach for reconstructing angiographic images by application of wavelet transforms on CT perfusion data. METHODS: Fifteen consecutive patients with suspected stroke were examined with a multi-detector CT acquiring 32 dynamic phases (∆t = 1.5s) of 99 slices (total slab thickness 99mm) at 80kV/200mAs. Thirty-five mL of iomeprol-350 was injected (flow rate = 4.5mL/s). Angiographic datasets were calculated after initial rigid-body motion correction using (a) temporally filtered maximum intensity projections (tMIP) and (b) the wavelet transform (Paul wavelet, order 1) of each voxel time course. The maximum of the wavelet-power-spectrum was defined as the angiographic signal intensity. The contrast-to-noise ratio (CNR) of 18 different vessel segments was quantified and two blinded readers rated the images qualitatively using 5pt Likert scales. RESULTS: The CNR for the wavelet angiography (501.8 ± 433.0) was significantly higher than for the tMIP approach (55.7 ± 29.7, Wilcoxon test p < 0.00001). Image quality was rated to be significantly higher (p < 0.001) for the wavelet angiography with median scores of 4/4 (reader 1/reader 2) than the tMIP (scores of 3/3). CONCLUSIONS: The proposed calculation approach for angiography data using temporal wavelet transforms of intracranial CT perfusion datasets provides higher vascular contrast and intrinsic removal of non-enhancing structures such as bone. KEY POINTS: • Angiographic images calculated with the proposed wavelet-based approach show significantly improved contrast-to-noise ratio. • CT perfusion-based wavelet angiography is an alternative method for vessel visualization. • Provides intrinsic removal of non-enhancing structures such as bone.