Quantitative analysis of dynamic computed tomography angiography for the detection of endoleaks after abdominal aorta aneurysm endovascular repair: A feasibility study

Objectives

To assess the feasibility of quantitative analysis of dynamic computed tomography angiography (dCTA) for the detection of endoleaks in patients who underwent endovascular repair of abdominal aortic aneurysms (EVAR).

Material and methods

Twenty patients scheduled for contrast-enhanced CT angiography (CTA) of the abdominal aorta post-EVAR were prospectively enrolled. All patients received a standard triphasic CTA protocol, followed by an additional dCTA. The dCTA acquisition enabled reconstruction of color-coded maps depicting blood perfusion and a dCTA dataset of the aneurysm sac. Observers assessed the dCTA and dynamic CT perfusion (dCTP) images for the detection of endoleaks, establishing diagnostic confidence based on a modified 5-point Likert scale. An index was calculated for the ratio between the endoleak and aneurysm sac using blood flow for dCTP and Hounsfield units (HU) for dCTA. The Wilcoxon test compared the endoleak index and the diagnostic confidence of the observers.

Results

In total, 19 patients (18 males, median age 74 years [70.5–75.7]) were included for analysis. Nine endoleaks were detected in 7 patients using triphasic CTA as the reference standard. There was complete agreement for endoleak detection between the two techniques on a per-patient basis. Both dCTA and dCTP identified an additional endoleak in one patient. The diagnostic confidence using dCTP for detection of endoleaks was not significantly superior to dCTA (5.0 [5–5] vs. 4.5 [4–5], respectively; p = 0.11); however, dCTP demonstrated superior diagnostic confidence for endoleak exclusion compared to dCTA (1.0 [1–1] vs 1.5 [1.5–1.5], respectively; p <0.01). Moreover, the dCTP endoleak index was significantly higher than the dCTA index (18.5 [10.8–20.5] vs. 3.5 [5–2.7], respectively; p = 0.02).

Conclusions

Quantitative analysis of dCTP imaging can aid in the detection of endoleaks and demonstrates a higher endoleak detection rate than triphasic CTA, as well as a strong correlation with visual assessment of dCTA images.

Carotid Plaque CTA Analysis in Symptomatic Subjects with Bilateral Intraparenchymal Hemorrhage: A Preliminary Analysis

BACKGROUND AND PURPOSE

The presence of IPH is considered the most dangerous feature because it is significantly associated with clinical ipsilateral cerebrovascular events. Our aim was to explore the characterization of plaque with CT in symptomatic subjects with bilateral intraplaque hemorrhage.

MATERIALS AND METHODS

Three-hundred-forty-three consecutive patients with recent anterior circulation ischemic events (<2 weeks) and CT of the carotid arteries (performed within 14 days of the cerebrovascular event) evaluated between June 2012 and September 2017 were analyzed for plaque volume composition to identify all subjects with bilateral intraplaque hemorrhage. Plaque volume was semiautomatically measured, and tissue components were classified according to the attenuation values such as the following: calcified (for values of ≥130 HU), mixed (for values of ≥60 and <130 HU), lipid (for values of ≥25 and <60 HU), and intraplaque hemorrhage (for values of <25 HU). Twenty-one subjects (15 men; mean age, 70 ± 11 years; range, 44-87 years) had bilateral intraplaque hemorrhage and were included in the analysis.

RESULTS

Volume measurement revealed significantly larger plaques on the symptomatic side compared with the asymptomatic one (mean, 28 ± 9 versus 22 ± 8 mm, P = .007). Intraplaque hemorrhage volume and percentage were also significantly higher in the plaque ipsilateral to the cerebrovascular event (P < .001 and < .001, respectively). The volume of other plaque components did not show a statically significant association except for lipid and lipid + intraplaque hemorrhage percentages (23% versus 18% and 11% versus 15%), which were significantly different between the symptomatic and the asymptomatic sides (.016 and .011, respectively). The intraplaque hemorrhage/lipid ratio was higher on the symptomatic side (0.596 versus 0.171, P = .001).

CONCLUSIONS

In patients with bilateral intraplaque hemorrhage and recent ischemic symptoms, the plaque ipsilateral to the symptomatic side has significantly larger volume and a higher percentage of intraplaque hemorrhage compared with the contralateral, asymptomatic side.

Does the clinical information play a role in the magnetic resonance diagnostic confidence analysis of ovarian and deep endometriosis?

OBJECTIVE:

Some recent studies have explored how the experience in the observers change their performance in the endometriosis detection using MRI but the effects of the clinical information remains uncertain. The purpose of this study was to assess the effect of the clinical information in the diagnostic confidence in the MRI diagnosis of endometriosis.

METHODS AND MATERIALS:

Institutional Review Board was obtained. This study is compliant to STARD method. 80 patients (mean age 32 years; range 19 - 46 years) who had undergone MRI study and surgery for suspected endometriosis were retrospectively evaluated. MRI exams were performed with a 1.5 T scanner and the following five locations were assessed: ovary, anterior compartment, vaginal fornix, utero-sacral ligaments, and Rectum\Sigmoid\Pouch of Douglas. Data sets were evaluated twice on a 5-point scale by four radiologists with different level of expertise; the first time blinded to the clinical information and the second time, after 3 months together with the clinical chart. Statistical analysis included receiver operating characteristics curve analysis, the Cohen weighted test and sensitivity, specificity, positive predictive value, negative predictive value, accuracy, LR+ and LR-.

RESULTS:

A total of 140 localization of endometriosis (47 endometriomas and 93 endometriotic nodules) were found. The pairwise comparison demonstrated that in all cases the presence of clinical information improved the Az value. The concordance analysis indicated a mixed pattern from modest agreement (weighted κ value 0.556 for anterior compartment) to excellent agreement values (weighted κ value 0.867 for ovarian endometriomas).

CONCLUSION:

The results of our study suggest that clinical information is useful in diagnosing endometriosis in general anterior compartment, but not in other locations. Less experienced radiologists (resident) may benefit from it at utero-sacral ligaments or Rectum\Sigmoid\Pouch of Douglas.

ADVANCES IN KNOWLEDGE:

In this era of sometimes indiscriminate use of diagnostic methods, it is important to emphasis the context for interpretation of diagnostic results. Our paper confirms that clinical information is useful in diagnosing endometriosis.

Prognostic value of CT myocardial perfusion imaging and CT-derived fractional flow reserve for major adverse cardiac events in patients with coronary artery disease

OBJECTIVES

The purpose of this study was to analyze the prognostic value of dynamic CT perfusion imaging (CTP) and CT derived fractional flow reserve (CT-FFR) for major adverse cardiac events (MACE).

METHODS

81 patients from 4 institutions underwent coronary computed tomography angiography (CCTA) with dynamic CTP imaging and CT-FFR analysis. Patients were followed-up at 6, 12, and 18 months after imaging. MACE were defined as cardiac death, nonfatal myocardial infarction, unstable angina requiring hospitalization, or revascularization. CT-FFR was computed for each major coronary artery using an artificial intelligence-based application. CTP studies were analyzed per vessel territory using an index myocardial blood flow, the ratio between territory and global MBF. The prognostic value of CCTA, CT-FFR, and CTP was investigated with a univariate and multivariate Cox proportional hazards regression model.

RESULTS

243 vessels in 81 patients were interrogated by CCTA with CT-FFR and 243 vessel territories (1296 segments) were evaluated with dynamic CTP imaging. Of the 81 patients, 25 (31%) experienced MACE during follow-up. In univariate analysis, a positive index-MBF resulted in the largest risk for MACE (HR 11.4) compared to CCTA (HR 2.6) and CT-FFR (HR 4.6). In multivariate analysis, including clinical factors, CCTA, CT-FFR, and index-MBF, only index-MBF significantly contributed to the risk of MACE (HR 10.1), unlike CCTA (HR 1.2) and CT-FFR (HR 2.2).

CONCLUSION

Our study provides initial evidence that dynamic CTP alone has the highest prognostic value for MACE compared to CCTA and CT-FFR individually or a combination of the three, independent of clinical risk factors.

Ultrasound-Based Automated Carotid Lumen Diameter/Stenosis Measurement and its Validation System

Objective

Degree of carotid stenosis is an important predictor to assess risk of stroke. Systolic velocity-based methods for lumen diameter and stenosis measurement are subjective. Image-based methods face a challenge because of low gradients in media and intima walls.

Methods

This article presents AtheroEdge™ 2.0, a two-stage process for automated carotid lumen diameter measurement that combats the above challenges. Stage one uses spectral analysis based on the hypothesis that far-wall adventitia is brightest. Stage two uses lumen pixel region identification based on the assumption that blood flow has constant density. Using global and local processing, lumen boundaries are detected. This clinical system outputs lumen diameter along with stenosis severity index (SSI).

Results

Our database consists of institutional review board–approved 202 patients (males/females: 155/47) left and right common carotid artery images (404 images, Toshiba scanner). Two trained neuro radiologists performed manual lumen border tracings using ImgTracer™ software. The coefficient of correlation between automated and two manual readings was 0.91 and 0.92. Dice similarity and Jaccard index were 95.82%, 95.72% and 92.10%, 91.92%, respectively. The mean diameter error between automated and two manual readings was 0.27 ± 0.26 and 0.26 ± 0.28 mm, respectively. Precision of merit was 98.05% and 99.03% with respect to two readings. SSI showed 97% accuracy.

Conclusions

The image-based automated carotid lumen diameter and stenosis measurement system is fast, accurate, and reliable.

Carotid inter-adventitial diameter is more strongly related to plaque score than lumen diameter: An automated tool for stroke analysis

PURPOSE

To compare the strength of correlation between automatically measured carotid lumen diameter (LD) and interadventitial diameter (IAD) with plaque score (PS).

METHODS

Retrospective study on a database of 404 common carotid artery B-mode sonographic images from 202 diabetic patients. LD and IAD were computed automatically using an advanced computerized edge detection method and compared with two distinct manual measurements. PS was computed by adding the maximal thickness in millimeters of plaques in segments taken from the internal carotid artery, bulb, and common carotid artery on both sides.

RESULTS

The coefficient of correlation was 0.19 (p < 0.007) between LD and PS, and 0.25 (p < 0.0006) between IAD and PS. After excluding 10 outliers, coefficient of correlation was 0.25 (p < 0.0001) between LD and PS, and 0.38 (p < 0.0001) between IAD and PS. The precision of merit of automated versus the two manual measurements was 96.6% and 97.2% for LD, and 97.7% and 98.1%, for IAD, respectively.

CONCLUSIONS

Our automated measurement system gave satisfying results in comparison with manual measurements. Carotid IAD was more strongly correlated to PS than carotid LD in this population sample of Japanese diabetic patients.

Automated calcium burden measurement in internal carotid artery plaque with CT: a hierarchical adaptive approach

AIM

Calcium burden measurement in internal carotid artery (ICA) plaque could play an important role in assessing stroke risk and stenosis quantification in the ICA. We propose an automatic method for labelling calcified plaques in ICA in CT images.

METHODS

Our approach builds upon the mean shift paradigm via an adaptive thresholding strategy. The data consists of single CT slices from 75 patients, with variety of plaque sizes and number of calcium regions. The manual measurements were carried out by a neuroradiologist for benchmarking. The calcium burden was measured as the area of the labelled plaque. Various metrics were employed to compare manual and automated measurements including correlation coefficient (CC), dice similarity (DS), Jacard Index (JI), polyline distance metric (PDM) and precision of merit (PoM).

RESULTS

We found that our automated method of calcium area characterization performed accurately compared to manual measurements with CC=0.978, and PoM=0.915. The PDM, DS, and JI, also indicate a good performance with a mean DS=0.85 (SD=0.085), a mean JI=0.747 (SD=0.12), and a mean PDM=0.195 (SD=0.177).

CONCLUSION

The proposed approach for calcium burden measurement, yields reasonably accurate labelling of calcified plaque when benchmarked against manual measurements. The approach is independent of the number and size of calcium regions, and the prototype design shows encouraging results to be adaptable to clinical practice.

Abstract 509: Accurate Measurement of Carotid Lumen Diameter and Narrowing Utilizing Ultrasound

Introduction: Ultrasound is often used for monitoring of carotid disease. In current clinical practice, degree of stenosis is an important predictor to assess stroke risk. Lumen narrowing from plaque is currently measured via techniques such as computed tomographic scan, magnetic resonance angiogram or conventional angiogram. Duplex ultrasound measures degree of stenosis based on peak systolic velocities and other parameters and only provides a wide range of level of stenosis. Pursuing lumen size measurement in ultrasound via manual quantification of lumen diameter is tedious. Furthermore, non-uniformity in plaque growth makes it more challenging and time-consuming. There has been an increasing interest in the automatic and robust delineation of the lumen boundaries of the carotids and to measure the lumen diameter via ultrasound given its non-invasive and safe approach.

Methods: Deidentified carotid ultrasound images were obtained on patients retrospectively who underwent carotid ultrasound at Toho University Ohashi Medical Center, Tokyo, Japan. A higher order derivative Gaussian filter is applied on these images to highlight the edges. Using pixel classification, lumen region is detected and lumen boundaries are estimated.

Results: Of the 202 patients with common carotid artery images, 155 were males and 47 were females.Mean age 69 ± 15.9 years. Mean HbA1c, LDL, HDL and Cholesterol of patients were 6.28±1.1 mg/dl, 101.27±31.6 mg/dl, 50.26±14.8 mg/dl and 175.04±38 mg/dl, respectively. Specialist trained in carotid ultrasound manually traced lumen diameter. Automated tracing and lumen measurements were obtained. The coefficient of correlation between automated diameter and manual diameter was: 0.88, 0.91 and 0.93. The mean diameter error between automated and manual tracing were: 0.50±0.37 mm, 0.36±0.34 mm and 0.30±0.28 mm. Precision of merit between automated diameter and manual diameter was: 93.28%, 95.33% and 96.32% corresponding to manual tracers.

Conclusions: The automated lumen diameter measurement is near real time, quick, accurate, fully automated and reliable to assess carotid lumen diameter and narrowing.