Getting beyond the myth of the bell-shaped density curve

2000 ◽  
Vol 19 (2) ◽  
pp. 29-32 ◽  
Author(s):  
Willian Roth
Keyword(s):  
Density Curve

scholarly journals Carotid webs produce greater hemodynamic disturbances than atherosclerotic disease: a DSA time–density curve study

2021 ◽  
pp. neurintsurg-2021-017588
Author(s):  
Charlie C Park ◽  
Retta El Sayed ◽  
Benjamin B Risk ◽  
Diogo C Haussen ◽  
Raul G Nogueira ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Carotid Artery ◽  
Carotid Arteries ◽  
Region Of Interest ◽  
Hemodynamic Parameters ◽  
Density Curve ◽  
Atherosclerotic Lesions ◽  
Clinically Significant ◽  
Flow Stasis ◽  
Time Density

BackgroundCarotid webs (CaWs) are associated with ischemic strokes in younger patients without degrees of stenosis that are traditionally considered clinically significant.ObjectiveTo compare the hemodynamic parameters in the internal carotid artery (ICA) bulbar segment in patients with CaW with those in patients with atherosclerotic lesions using time–density curve (TDC) analysis of digital subtraction angiography (DSA) images.MethodsWe retrospectively assessed DSA images of 47 carotid arteries in 41 adult patients who underwent ICA catheter angiography for evaluation after ischemic stroke. Hemodynamic parameters, including full width at half maximum (FWHM) and area under the time–density curve (AUC) as proxies for increased flow stasis, were calculated using TDC analyses of a region of interest (ROI) in the ICA bulb immediately rostral to the web/atherosclerotic plaque, relative to a standardized ROI in the ipsilateral distal common carotid artery (eg, relative FWHM (rFWHM)). Hemodynamic parameters were compared using non-parametric Kruskal-Wallis tests. Logistic regression was used to predict CaW versus mild/moderate atherosclerosis for each hemodynamic parameter, adjusting for degree of stenosis.ResultsMean age of patients was 56.0±13 years, with 22 (53.7%) women. 17 CaWs, 22 atherosclerotic plaques (15 mild/moderate and 7 severe), and eight normal carotid arteries were assessed. Significant between-group differences were present in the relative total AUC (p<0.001), relative AUC at wash out (p=0.031), and relative FWHM (p=0.001). Logistic regression to predict CaW versus mild/moderate atherosclerosis showed that rAUC total had the highest predictive value (pAUC=0.96, 95% CI 0.90 to 1.00), followed by rFWHM (0.87, 95% CI 0.74 to 1.00), and rAUC WO (0.74, 95% CI (0.57 to 0.91).ConclusionCaW results in larger local hemodynamic disruption, characterized by flow stasis, than mild/moderate carotid atherosclerotic lesions, suggesting that CaWs may produce larger regions of thrombogenic flow stasis.

scholarly journals Standing balance in preschoolers using nonlinear dynamics and sway density curve analysis

2019 ◽  
Vol 82 ◽  
pp. 96-102 ◽  
Author(s):  
Paula Hentschel Lobo da Costa ◽  
Evi Verbecque ◽  
Ann Hallemans ◽  
Marcus Fraga Vieira
Keyword(s):  
Nonlinear Dynamics ◽  
Curve Analysis ◽  
Standing Balance ◽  
Density Curve

Optical density curve model for CD-R dye coating

2003 ◽  
Author(s):  
Hongda Yue ◽  
Longfa Pan ◽  
Yuejing Bin ◽  
Ken Chen
Keyword(s):  
Optical Density ◽  
Density Curve ◽  
Curve Model ◽  
Optical Density Curve

scholarly journals Feasibility of CBCT ‐based dose with a patient‐specific stepwise HU ‐to‐density curve to determine time of replanning

2017 ◽  
Vol 18 (5) ◽  
pp. 64-69 ◽  
Author(s):  
Shifeng Chen ◽  
Quynh Le ◽  
Yildirim Mutaf ◽  
Wei Lu ◽  
Elizabeth M. Nichols ◽  
...  
Keyword(s):  
Patient Specific ◽  
Density Curve

scholarly journals Time density curve analysis for C-arm FDCT PBV imaging

2016 ◽  
Vol 22 (2) ◽  
pp. 176-186 ◽  
Author(s):  
Mudassar Kamran ◽  
James V Byrne
Keyword(s):  
Steady State ◽  
Goodness Of Fit ◽  
Contrast Material ◽  
Horizontal Line ◽  
Cerebral Vasculature ◽  
Line Model ◽  
Density Curve ◽  
Injection Protocol ◽  
The Individual ◽  
Time Density

Introduction Parenchymal blood volume (PBV) estimation using C-arm flat detector computed tomography (FDCT) assumes a steady-state contrast concentration in cerebral vasculature for the scan duration. Using time density curve (TDC) analysis, we explored if the steady-state assumption is met for C-arm CT PBV scans, and how consistent the contrast-material dynamics in cerebral vasculature are across patients. Methods Thirty C-arm FDCT datasets of 26 patients with aneurysmal-SAH, acquired as part of a prospective study comparing C-arm CT PBV with MR-PWI, were analysed. TDCs were extracted from the 2D rotational projections. Goodness-of-fit of TDCs to a steady-state horizontal-line-model and the statistical similarity among the individual TDCs were tested. Influence of the differences in TDC characteristics on the agreement of resulting PBV measurements with MR-CBV was calculated. Results Despite identical scan parameters and contrast-injection-protocol, the individual TDCs were statistically non-identical ( p < 0.01). Using Dunn's multiple comparisons test, of the total 435 individual comparisons among the 30 TDCs, 330 comparisons (62%) reached statistical significance for difference. All TDCs deviated significantly ( p < 0.01) from the steady-state horizontal-line-model. PBV values of those datasets for which the TDCs showed largest deviations from the steady-state model demonstrated poor agreement and correlation with MR-CBV, compared with the PBV values of those datasets for which the TDCs were closer to steady-state. Conclusion For clinical C-arm CT PBV examinations, the administered contrast material does not reach the assumed ‘ideal steady-state’ for the duration of scan. Using a prolonged injection protocol, the degree to which the TDCs approximate the ideal steady-state influences the agreement of resulting PBV measurements with MR-CBV.

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