Multi-Energy Low-Kiloelectron Volt versus Single-Energy Low-Kilovolt Images for Endoleak Detection at CT Angiography of the Aorta.

Purpose To compare image quality, diagnostic performance, and conspicuity between single-energy and multi-energy images for endoleak detection at CT angiography (CTA) after endovascular aortic repair (EVAR). Materials and Methods In this single-center prospective randomized controlled trial, individuals undergoing CTA after EVAR between August 2020 and May 2022 were allocated to imaging using either low-kilovolt single-energy images (SEI; 80 kV, group A) or low-kiloelectron volt virtual monoenergetic images (VMI) at 40 and 50 keV from multi-energy CT (80/Sn150 kV, group B). Scan protocols were dose matched (volume CT dose index: mean, 4.5 mGy ± 1.8 [SD] vs 4.7 mGy ± 1.3, P = .41). Contrast-to-noise ratio (CNR) was measured. Two expert radiologists established the reference standard for the presence of endoleaks. Detection and conspicuity of endoleaks and subjective image quality were assessed by two different blinded radiologists. Interreader agreement was calculated. Nonparametric statistical tests were used. Results A total of 125 participants (mean age, 76 years ± 8; 103 men) were allocated to groups A (n = 64) and B (n = 61). CNR was significantly lower for 40-keV VMI (mean, 19.1; P = .048) and 50-keV VMI (mean, 16.8; P < .001) as compared with SEI (mean, 22.2). In total, 45 endoleaks were present (A: 23 vs B: 22). Sensitivity for endoleak detection was higher for SEI (82.6%, 19 of 23; P = .88) and 50-keV VMI (81.8%, 18 of 22; P = .90) as compared with 40-keV VMI (77.3%, 17 of 22). Specificity was comparable among groups (SEI: 92.7%, 38 of 41; both VMI energies: 92.3%, 35 of 38; P = .99), with an interreader agreement of 1. Conspicuity of endoleaks was comparable between SEI (median, 2.99) and VMI (both energies: median, 2.87; P = .04). Overall subjective image quality was rated significantly higher for SEI (median, 4 [IQR, 4-4) as compared with 40 and 50 keV (both energies: median, 4 [IQR, 3-4]; P < .001). Conclusion SEI demonstrated higher image quality and comparable diagnostic accuracy as compared with 50-keV VMI for endoleak detection at CTA after EVAR. Keywords: Aneurysms, CT, CT Angiography, Vascular, Aorta, Technology Assessment, Multidetector CT, Abdominal Aortic Aneurysms, Endoleaks, Perigraft Leak Supplemental material is available for this article. © RSNA, 2024.

CT Angiography of the Aorta Using Photon-counting Detector CT with Reduced Contrast Media Volume.

Purpose: To develop and evaluate a low-volume contrast media protocol for thoracoabdominal CT angiography (CTA) with photon-counting detector (PCD) CT. Materials and Methods: This prospective study included consecutive participants (April-September 2021) who underwent CTA with PCD CT of the thoracoabdominal aorta and previous CTA with energy-integrating detector (EID) CT at equal radiation doses. In PCD CT, virtual monoenergetic images (VMI) were reconstructed in 5-keV intervals from 40 to 60 keV. Attenuation of the aorta, image noise, and contrast-to-noise ratio (CNR) were measured, and subjective image quality was rated by two independent readers. In the first group of participants, the same contrast media protocol was used for both scans. CNR gain in PCD CT compared with EID CT served as the reference for contrast media volume reduction in the second group. Noninferiority analysis was used to test noninferior image quality of the low-volume contrast media protocol with PCD CT. Results: The study included 100 participants (mean age, 75 years ± 8 [SD]; 83 men). In the first group (n = 40), VMI at 50 keV provided the best trade-off between objective and subjective image quality, achieving 25% higher CNR compared with EID CT. Contrast media volume in the second group (n = 60) was reduced by 25% (52.5 mL). Mean differences in CNR and subjective image quality between EID CT and PCD CT at 50 keV were above the predefined boundaries of noninferiority (-0.54 [95% CI: -1.71, 0.62] and -0.36 [95% CI: -0.41, -0.31], respectively). Conclusion: CTA of the aorta with PCD CT was associated with higher CNR, which was translated into a low-volume contrast media protocol demonstrating noninferior image quality compared with EID CT at the same radiation dose.Keywords: CT Angiography, CT-Spectral, Vascular, Aorta, Contrast Agents-Intravenous, Technology Assessment© RSNA, 2023See also the commentary by Dundas and Leipsic in this issue.

The PEARL Approach for CT-guided Lung Biopsy: Assessment of Complication Rate.

Background Percutaneous CT-guided biopsy of lung nodules is an established method with high diagnostic accuracy but a high rate of pneumothorax and chest tube insertion compared with endobronchial methods. Purpose To investigate the effect of a protocol combining patient positioning biopsy-side down, needle removal during expiration, autologous blood patch sealing, rapid rollover, and pleural patching (PEARL) on complication rate after percutaneous CT-guided lung biopsy, especially chest tube insertion. Materials and Methods In a secondary analysis of both prospectively and retrospectively acquired data from December 2019 to November 2020, consecutive participants underwent biopsy with use of the PEARL protocol (prospective data) and were compared with patients who underwent biopsy at the same tertiary cancer center according to the standard method without any additional techniques (controls, retrospective data). Patient demographics, lesion characteristics, intraprocedural data, complications, and histologic results were recorded and compared. Results One hundred patients in the control group (mean age ± standard deviation, 63 years ± 12; 61 men) and 100 participants in the PEARL group (mean age, 64 years ± 12; 48 men) were evaluated. No differences were found in patient and lesion characteristics. The emphysema rate was 47 of 100 patients (47%) in both groups. The rate of pneumothorax was 37 of 100 patients (37%) in the control group versus 16 of 100 (16%) in the PEARL group (P = .001). Of the pneumothoraxes that occurred, fewer were during the intervention in the PEARL group, with 21 of 37 onsets (57%) in the control group versus three of 16 onsets (19%) in the PEARL group (P < .001). A chest tube was inserted in 13 of 100 patients (13%) in the control group and only in one of 100 (1%) in the PEARL group (P = .002). Histologic findings were diagnostic in 94 of 100 patients (94%) in the control group and 95 of 100 (95%) in the PEARL group (P > .99). Conclusion During CT-guided percutaneous lung biopsy, a protocol of positioning biopsy-side down, needle removal during expiration, autologous blood patch sealing, rapid rollover, and pleural patching, or PEARL, reduced rates of pneumothorax and chest tube insertion. © RSNA, 2021.