3-D Contrast-Enhanced Fusion Ultrasound for Accurate Volume Assessment of Vessel Lumen and Plaque in Carotid Artery Disease as Compared With Computed Tomography Angiography.

OBJECTIVE: Three-dimensional contrast-enhanced fusion ultrasound (CEFUS) of atherosclerotic carotid arteries provides spatial visualization of the vessel lumen, creating a lumenography. As in 3-D computed tomography angiography (CTA), 3-D CEFUS outlines the contrast-filled lumen. Plaque and vessel contours are distinguished in 3-D CEFUS, allowing plaque volume quantification as a valid estimate of carotid plaque burden. Three-dimensional CEFUS is unproven in intermodality studies, vindicating the assessment of 3-D CEFUS applicability and comparing 3-D CEFUS and 3-D CTA lumenography as a proof-of-concept study. METHODS: Using an ultrasound system with magnetic tracking, a linear array transducer and SonoVue contrast agent, 3-D CEFUS acquisitions were generated by spatial stitching of serial 2-D images. From 3-D CEFUS and 3-D CTA imaging, the atherosclerotic carotid arteries were reconstructed with lumenography in an offline software program for lumen and plaque volume quantification. Bland-Altman analysis was used for inter-image modality agreement. RESULTS: The study included 39 carotid arteries. Mean lumen and plaque volume in 3-D CEFUS were 0.63 cm3 (standard deviation [SD]: 0.26) and 0.62 cm3 (SD: 0.26), respectively. Lumen volume differences between 3-D CEFUS and 3-D CTA were non-significant, with a mean difference of 0.01 cm3 (SD: 0.02, p = 0.26) and limits of agreement (LoA) range of ±0.11 cm3. Mean plaque volume difference was -0.12 cm3 (SD: 0.19, p = 0.006) with a LoA range of ±0.39 cm3. CONCLUSION: There was strong agreement in lumenography between 3-D CEFUS and 3-D CTA. The interimage modality difference in plaque volumes was substantial because of challenging vessel wall definition in 3-D CTA. Three-dimensional CEFUS is viable in quantifying carotid plaque volume burden and can potentially monitor plaque development over time.

Full-Volume Assessment of Abdominal Aortic Aneurysm by Improved-Field-of-View 3-D Ultrasound Performs Comparably to Computed Tomographic Angiography.

Three-dimensional ultrasound (US) of abdominal aortic aneurysms (AAAs) is limited by the field-of-view of the 3D-US transducer. To obtain an extended field-of-view (XFoV), two transducer navigation system-assisted US protocols have been developed: XFoV-2D and XFoV-3D. In this study, the XFoV US protocols were compared with the currently available 3D-US protocol with standard field-of-view (FoV-st) and the established gold standard, computed tomography angiography (CTA). A total of 65 patients with AAA were included, and AAA imaging was processed offline with prototype software. The novel XFoV-2D and XFoV-3D protocols allowed for assessment of full AAA volume in significantly more patients (45/65 [69%] and 43/65 [66%], respectively), compared with the current 3D-US standard, FoV-st (30/65 [46%] patients). The mean difference in AAA volume estimation between each XFoV US protocol and 3-D CTA differed significantly (XFoV-2D: 16.9 mL, XFoV-3D: 7.6 mL, p = 0.002), indicating that XFoV-3D agreed best with 3D-CTA. No significant difference was found in the variance of full AAA volume quantification between each XFoV US protocol and CTA (p = 0.49). It is concluded that the XFoV US protocols improved the generation of full AAA volumes compared with the currently available 3D-US technology, with AAA volume estimates comparable to CTA estimates.

Full-Volume Assessment of Abdominal Aortic Aneurysms by 3-D Ultrasound and Magnetic Tracking.

Volume assessment of abdominal aortic aneurysms (AAAs) using 3-D ultrasound (US) is an innovative technique reporting good agreement with computed tomography angiography. One major limitation of the current 3-D US technique is a limited field of view, allowing full AAA acquisition in only 60% of patients. This study presents two new US acquisition protocols using magnetic field tracking, providing an "extended field of view" (XFoV-2-D and XFoV-3-D) with the aim of including both the aortic bifurcation and neck for full-volume assessment, and compares these methods with the current standard 3-D US protocol and with computed tomography angiography. A total of 20 AAA patients were included and underwent the current standard 3-D US protocol and the two novel 3-D US "extended field of view" protocols. Four patients were excluded from further analysis because of low image quality, leaving 16 patients eligible for analysis. Full AAA volume was achieved in 8 patients (50%) using the standard 3-D US protocol, in 11 patients (69%) with the XFoV-2-D protocol and in 13 patients (81%) with the XFoV-3-D protocol. In conclusion, this article describes two new and feasible US protocols applicable for full-AAA-volume estimation in most patients and should initiate further research into the added value of full volume in AAA surveillance.

Elevated Renal Oxygen Extraction During Open Abdominal Aortic Aneurysm Repair Is Related to Postoperative Renal Dysfunction.

BACKGROUND: Open abdominal aortic aneurysm repair is often followed by elevated plasma creatinine, likely due to impaired renal blood flow. We evaluated whether postoperative elevation in creatinine relates to renal oxygen extraction during surgery as an index of renal blood flow and also monitored frontal lobe oxygenation. METHODS: For 19 patients (66 ± 10 years; mean ± SD) undergoing open infrarenal abdominal aortic aneurysm repair, renal oxygen extraction was determined by arterial and renal vein catheterization. Near-infrared spectroscopy determined frontal lobe oxygenation. RESULTS: During surgery mean arterial pressure (from 102 ± 14 to 65 ± 11 mm Hg; P < .0001), arterial hemoglobin (from 7.7 ± 0.7 to 6.6 ± 0.8 mmol/L; P < 0.0001), and frontal lobe oxygenation (from 74 ± 6% to 70 ± 6%; P = .0414) decreased, while renal oxygen extraction increased (from 5.3% [4.3-8.1]; median [interquartile range] to 10.8% [5.8-17.5]; P = .0405). Plasma creatinine became significantly elevated on the second day after the operation (from 83 [73-101] to 105 µmol/L [79-143]; P = .0062) with a peak increase observed after 2 days (1-2). The peak increase in creatinine correlated to intraoperative renal oxygen extraction ( r = 0.51; P = .026). CONCLUSION: Kidney function was affected after open abdominal aortic aneurysm repair likely related to limited renal blood flow. We take the increase in renal oxygen extraction and reduction in frontal lobe oxygenation to suggest that mean arterial pressure and hemoglobin were too low to maintain renal and cerebral circulation in vascular surgical patients.