Characterization Of Aneurysms Research Articles

In Vivo Molecular Characterization of Abdominal Aortic Aneurysms Using Fibrin-Specific Magnetic Resonance Imaging.

BackgroundThe incidence of abdominal aortic aneurysms (AAAs) will significantly increase during the next decade. Novel biomarkers, besides diameter, are needed for a better characterization of aneurysms and the estimation of the risk of rupture. Fibrin is a key protein in the formation of focal hematoma associated with the dissection of the aortic wall and the development of larger thrombi during the progression of AAAs. This study evaluated the potential of a fibrin‐specific magnetic resonance (MR) probe for the in vivo characterization of the different stages of AAAs.Methods and Results AAAs spontaneously developed in ApoE−/− mice following the infusion of angiotensin‐II (Ang‐II, 1 μg/kg−1·per minute). An established fibrin‐specific molecular MR probe (EP2104R, 10 μmol/kg−1) was administered after 1 to 4 weeks following Ang‐II infusion (n=8 per group). All imaging experiments were performed on a clinical 3T Achieva MR system with a microscopy coil (Philips Healthcare, Netherlands). The development of AAA‐associated fibrin‐rich hematoma and thrombi was assessed. The high signal generated by the fibrin probe enabled high‐resolution MR imaging for an accurate assessment and quantification of the relative fibrin composition of focal hematoma and thrombi. Contrast‐to‐noise‐ratios (CNRs) and R1‐relaxation rates following the administration of the fibrin probe were in good agreement with ex vivo immunohistomorphometry (R 2=0.83 and 0.85) and gadolinium concentrations determined by inductively coupled plasma mass spectroscopy (R 2=0.78 and 0.72).ConclusionsThe fibrin‐specific molecular MR probe allowed the delineation and quantification of changes in fibrin content in early and advanced AAAs. Fibrin MRI could provide a novel in vivo biomarker to improve the risk stratification of patients with aortic aneurysms.

Abstract T P52: Technique for Measurement of Traumatic Aneurysms of the Cervical Internal Carotid Artery and Assessment of Reproducibility

Background: Traumatic aneurysms occur in 10-20% of blunt traumatic extracranial carotid artery injuries. There is currently no standardized method for characterization of traumatic aneurysms. This study presents a systematic method for aneurysm characterization on both digital subtraction angiography (DSA) and CT angiography (CTA). Methods: Four raters, including one vascular neurosurgeon, one neuroradiologist, and two senior neurosurgical residents independently reviewed 15 CTAs and 13 DSAs obtained at the time of diagnosis of the traumatic aneurysm. Raters were asked to categorize the aneurysms as either ‘saccular’ or ‘fusiform’ and obtain measurements. Saccular aneurysm size was defined as the greatest linear distance between the expected location of the normal artery wall and the outer edge of the aneurysm lumen (‘depth’). Fusiform aneurysm size was defined as the depth and longitudinal extent (‘length’) parallel to the normal artery. The size of the aneurysm (‘aneurysm plus parent artery’) in relationship to the normal artery (‘parent artery’) was assessed as well. Assessments of five scans of each imaging modality were repeated for measurement of intra-rater reliability. Fleiss's free-marginal multi-rater kappa (κ), Cohen’s kappa (κ), and interclass correlation coefficient (ICC) were applied to determine inter- and intra-rater reliability. Results: Inter-rater agreement on aneurysm shape, ‘saccular’ versus ‘fusiform’, was almost perfect for CTA (κ = 0.82) and DSA (κ = 0.897). Agreement on aneurysm ‘depth’, ‘length’, ‘aneurysm plus parent artery’, and ‘parent artery’ for CTA and DSA were excellent (ICC > 0.75). Intra-rater agreement on aneurysm shape was substantial to almost perfect (κ > 0.6) in all four raters. Conclusions: This study demonstrates a clinically oriented, standardized method to characterize traumatic aneurysms with remarkable inter- and intra-rater reliability. This approach may help to define this disease entity more clearly and better understand the natural history. While certain characteristics of traumatic aneurysms may be associated with low risk and treatment with antithrombotic therapy may be sufficient, other characteristics may carry increased risk warranting endovascular repair.

Sixteen-row multislice computed tomography angiography in the diagnosis and characterization of intracranial aneurysms: comparison with conventional angiography and intraoperative findings

The goal of this study was to prospectively compare the effectiveness of 16-slice computed tomography (CT) angiography with that of conventional digital subtraction (DS) angiography and the surgical findings used to detect and characterize intracranial aneurysms. Two hundred forty-four consecutive patients underwent both CT angiography and DS angiography no more than 3 days apart. Computed tomography angiography was performed with a 16-row multislice CT scanner in which a collimation of 0.75 mm was used. Two observers independently reviewed the CT images, and 1 of the 3 attending neuroradiologists reviewed the DS angiograms. They determined the presence, location, quantitation, and characterization of the intracranial aneurysms. Statistical results were calculated independently for the image interpretation performed by the 2 CT scan readers and the DS angiogram reader by using the combination of DS angiography or intraoperative findings or both as a reference standard. One hundred thirty-six patients harboring 153 intracranial aneurysms were included in this series. There was no statistically significant difference in sensitivity between 16-slice CT angiography and conventional DS angiography (p > 0.05). The sensitivities of 16-slice CT angiography for aneurysms < 5 mm, 5-10 mm, and > 10 mm were 94.8, 100, and 100%, respectively, on a per-aneurysm basis. The overall sensitivity and specificity of CT angiography for aneurysms were 98.0 and 99.1%, respectively. Sixteen-slice CT angiograms were clearer and more accurate in depicting the relationship of aneurysms to bone structures and adjacent branch vessels. Computed tomography angiography using a 16-slice scanner is an accurate tool for detecting and characterizing intracranial aneurysms, including small aneurysms. Noninvasive 16-slice CT angiography will become a viable replacement for conventional DS angiography in the diagnosis and characterization of aneurysms.

3-T Contrast-Enhanced MR Angiography in Evaluation of Suspected Intracranial Aneurysm: Comparison with MDCT Angiography

The purpose of this study was to prospectively evaluate a high-spatial-resolution contrast-enhanced 3-T MR angiography protocol for detection and characterization of intracranial aneurysms and to compare the results with those of MDCT angiography. Forty-one patients with suspected intracranial aneurysm underwent high-spatial-resolution 3D contrast-enhanced MR angiography and CT angiography (CTA). With a generalized autocalibrating partially parallel acquisition algorithm with an acceleration factor of 4 at 3 T, contrast-enhanced MR angiographic images were acquired over 20 seconds with a spatial-resolution of 0.7 x 0.7 x 0.8 mm. CTA images were acquired with a spatial resolution of 0.35 x 0.35 x 0.8 mm on a 16-MDCT scanner in 17 seconds. The images from the two studies were evaluated independently by two neuroradiologists for image quality, presence of aneurysm, and characterization of aneurysm. The dimensions of the aneurysm were measured independently with both techniques. A total of 25 aneurysms were identified with both contrast-enhanced MR angiography and CTA. A comparative analysis of detection and depiction of aneurysms showed excellent interobserver agreement for both contrast-enhanced MR angiography (kappa = 0.81) and CTA (kappa = 0.91) images. There was significant correlation between the techniques for both qualitative assessment of aneurysm depiction (rho = 0.92; 95% CI, 0.88-0.95) and quantitative dimensional measurement of aneurysm size (r = 0.94; 95% CI, 0.92-0.97). Contrast-enhanced MR angiography at 3 T is reliable for evaluation and characterization of intracranial aneurysms. The results are comparable with those of MDCTA.

Computed tomography angiography in detection and characterization of ruptured anterior cerebral artery aneurysms at uncommon location for emergent surgical clipping

Introduction Cerebral subarachnoid hemorrhage may result from rupture of saccular aneurysms at uncommon location [excluding the anterior communicating artery (ACOM)] of the anterior cerebral artery (ACA). The purpose of this study was to evaluate the usefulness of helical computed tomography angiography (CTA) in detection and characterization of intracranial aneurysms at such uncommon locations before emergent surgical clipping. Materials and methods Between 1998 and 2003, records for 50 consecutive patients who underwent emergent surgical clipping for intracranial aneurysms were reviewed. Eighteen of these patients had aneurysms in the ACA. After those patients with unequivocal ACOM aneurysms were excluded, eight patients with eight aneurysms in an uncommon location of the ACA were recruited to this study. Plain computed tomography (CT) and CTA were performed in eight patients, and digital subtraction angiographies were done in three patients. Each aneurysm was evaluated for the detection, quantification, and characterization of the aneurysms with 2D multiplanar reformatted and 3D volume-rendering techniques. Results There were two small aneurysms arising from the A1 segment, one from the A2 segment, two at the junction of triplicated ACAs, two at the junction of A2 and A3 segments, and one at the junction of A2 and A3 segments of the azygos ACA. The average diameter of the aneurysmal sac was 4.44 mm (range, 2.7–7.0 mm), and the aneurysmal neck averaged 2.59 mm (range, 1.2–3.5 mm) in size. The smallest aneurysm measured 2.2×1.8×2.7 mm (neck, 1.2 mm) in the A1 segment of the left ACA. Three patients had intracerebral hematoma, seven had intraventricular hemorrhage, and three had acute hydrocephalus. Conclusion Aneurysms in uncommon locations of ACAs exhibited characteristic features. Rupture of these aneurysms can cause intracerebral hematoma, intraventricular hemorrhage, and/or acute hydrocephalus. Noninvasive CTA can reliably detect and characterize intracranial aneurysms at such uncommon location for planning of emergent surgical intervention.