Evaluation of Virtual Monoenergetic Images on Pulmonary Vasculature Using the Dual-Layer Detector-Based Spectral Computed Tomography

Ghandour, Abed; Sher, Andrew; Rassouli, Negin; Dhanantwari, Amar; Rajiah, Prabhakar

doi:10.1097/rct.0000000000000748

Cited by 23 publications

(17 citation statements)

References 20 publications

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“…Based on prior studies, which reported an improvement in quantitative image quality by low-keV VMI+, [10][11][12][13][14][15][16][22][23][24] we aimed to assess if this beneficial effect could be exploited to improve endoleak detection. Increased iodine attenuation of low-keV VMI+ is based on the fact that their energy levels (40 and 50 keV) are closer to the k-edge of FIGURE 2.…”

Section: Discussionmentioning

confidence: 99%

Dual-Energy Low-keV or Single-Energy Low-kV CT for Endoleak Detection?

et al. 2019

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The aim of this study was to compare image quality, conspicuity, and endoleak detection between single-energy low-kV images (SEIs) and dual-energy low-keV virtual monoenergetic images (VMIs+) in computed tomography angiography of the aorta after endovascular repair. MATERIALS AND METHODS: An abdominal aortic aneurysm phantom simulating 36 endoleaks (2 densities; diameters: 2, 4, and 6 mm) in a medium-and large-sized patient was used. Each size was scanned using single-energy at 80 kVp (A) and 100 kVp (B), and dual-energy at 80/Sn150kVp for the medium (C) and 90/Sn150kVp for the large size (D). VMIs+ at 40 keV and 50 keV were reconstructed from protocols C and D. Radiation dose was 3 mGy for the medium and 6 mGy for the large size. Objective image quality and normalized noise power spectrum were determined. Subjective image quality, conspicuity, and sensitivity for endoleaks were independently assessed by 6 radiologists. Sensitivity was compared using Marascuilo procedure and Fisher exact test. Conspicuities were compared using Wilcoxon-matched pairs test, analysis of variance, and Tukey test. RESULTS: The contrast-to-noise-ratio of the aorta was significantly higher for VMI+ compared with SEI (P < 0.001). Noise power spectrum showed a higher noise magnitude and coarser texture in VMI+. Subjective image quality and overall conspicuity was lower for VMI+ compared with SEI (P < 0.05). Sensitivity for endoleaks was overall higher in the medium phantom for SEI (60.9% for A, 62.2% for B) compared with VMI+ (54.2% for C, 49.3% for D) with significant differences between protocols B and D (P < 0.05). In the large phantom, there was no significant difference in sensitivity among protocols (P = 0.79), with highest rates for protocols B (31.4%) and C (31.7%). CONCLUSIONS: Our study indicates that low-keV VMI+ results in improved contrast-to-noise-ratio of the aorta, whereas noise properties, subjective image quality, conspicuity, and sensitivity for endoleaks were overall superior for SEI.

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Section: Discussionmentioning

confidence: 99%

Dual-Energy Low-keV or Single-Energy Low-kV CT for Endoleak Detection?

et al. 2019

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“…Schueller-Weidekamm et al compared standard 140 kVp CT angiography with the 100 kVp and demonstrated an increase in percentage of central and peripheral pulmonary arteries that could be evaluated with CT angiography (12). Recently, several investigators reported the added value of dual energy CT systems using VMI reconstructions in CT angiography studies (13)(14)(15)(16) (18). Ghandour et al, compared conventional (120 kVp) images with the optimal monoenergetic level and showed a significant improvement of attenuation, SNR and CNR using dual layer spectral CT, advocating the 50 keV images as the optimal monoenergetic level (14).…”

Section: Standard Cnr Clot Ratio Best Cnr Clot Ratiomentioning

confidence: 99%

“…In the current study, we found that the benefit of low kiloelectronvolt VMI is its potential to improve the suboptimal pulmonary CT angiography studies using rapid kVp switch dual energy CT. Several prior studies have assessed dual energy CT for suboptimal enhancement in the pulmonary artery, however the patient population and CT protocols of these studies were heterogeneous (14,19). Different contrast volumes and acquisition parameters were used.…”

Section: Standard Cnr Clot Ratio Best Cnr Clot Ratiomentioning

confidence: 99%

Salvage of Suboptimal Enhancement of Pulmonary Artery in Pulmonary CT Angiography Studies: Rapid kVp Switch Dual Energy CT Experience

et al. 2020

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Background: Multidetector computed tomography (MDCT) angiography is considered as the gold standard imaging modality in the evaluation of acute pulmonary embolism. Optimum vascular enhancement is critical for MDCT studies. The suboptimal opacification in pulmonary artery could be salvaged using low-energy virtual monoenergetic images (VMI) at rapid kVp switch dual energy CT. Objectives: To explore the potential improvement in pulmonary artery opacification and to assess the change in image quality parameters in VMI using fast switch kVp dual energy CT. Patients and Methods: The CT images of 877 patients who were referred with a preliminary diagnosis of pulmonary embolism were reviewed. Sixty patients with suboptimal enhancement (< 200 Hounsfeld Unit [HU]) were involved. Standard images (140 kVp) and VMI from 40 to 120 keV were generated. Attenuation, noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were measured in the pulmonary artery. Using VMIs, the best image was determined as the image with the main pulmonary artery opacification greater than 200 HU and image quality ≥ 3. Fifty six studies that met these criteria were considered as salvaged. At this best energy level, quantitative parameters were compared with standard images. Results: The mean attenuation of pulmonary arteries was 169.80 HU in standard images in patients with suboptimal enhancement. The attenuations of VMIs at 40, 45, 50, 55, 60, 65, and 70 keV were significantly higher than standard images (P < 0.001). Similar findings were observed with SNR and CNR. In the salvaged patients, the average increase in mean pulmonary artery attenuation was 62% (from 172.61 ± 23.4 to 280.55 ± 40.7), the average increase in SNR was 38% (from 12.1 ± 5.3 to 16.7 ± 7.1) and the average increase in CNR was 48% (9.2 ± 4.3 to 13.7 ± 6) (P < 0.001). Conclusions: Low keV VMI reconstructions significantly increase pulmonary artery attenuation, CNR and SNR compared to standard image reconstructions. Suboptimal CT studies could be salvaged using low keV VMIs.

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“…1). VMI at low energies (< 70 keV) are used to improve the signal from contrast, which can be used to salvage suboptimal vascular studies or prospectively use a lower dose of intravenous contrast [13]. High energy VMI can be used for decreasing artifacts, e. g. caused by metallic implants.…”

Section: Computed Tomographymentioning

confidence: 99%

Acute Pulmonary Embolism: Imaging Techniques, Findings, Endovascular Treatment and Differential Diagnoses

Palm

Rengier

Rajiah

et al. 2019

Fortschr Röntgenstr

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Background Acute thrombotic pulmonary embolism (PE) is a common and potentially fatal event with imaging playing a pivotal role in the diagnosis and management of these patients. Method This review discusses imaging techniques, diagnostic algorithms, imaging findings and endovascular treatment of acute thrombotic PE, and illustrates important differential diagnoses relating to the spectrum of acute non-thrombotic PE and non-embolic pulmonary artery disease. The review emphasizes information relevant for everyday radiological practice and highlights recent advances that can be readily applied in the clinical routine. Results/Conclusion Computed tomography pulmonary angiography (CTPA) is the current reference standard for the diagnosis of acute PE. Ventilation and perfusion (VQ) scanning or – in centers with adequate expertise – magnetic resonance imaging (MRI) is indicated in pregnant or young patients and patients with contraindications to iodinated contrast. Invasive angiography is reserved for patients with intended endovascular treatment. Artifacts, acute non-thrombotic PE, chronic PE and non-embolic pulmonary artery diseases should always be considered as differential diagnoses. Key points: Citation Format

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Evaluation of Virtual Monoenergetic Images on Pulmonary Vasculature Using the Dual-Layer Detector-Based Spectral Computed Tomography

Abstract: Suboptimal enhanced pulmonary arterial CT studies can be salvaged using low-energy VMI generated from the SDCT scanner. There were significant improvements of attenuation, SNR, and CNR at the optimal monoenergetic level.

Cited by 23 publications

References 20 publications

Dual-Energy Low-keV or Single-Energy Low-kV CT for Endoleak Detection?

Dual-Energy Low-keV or Single-Energy Low-kV CT for Endoleak Detection?

Salvage of Suboptimal Enhancement of Pulmonary Artery in Pulmonary CT Angiography Studies: Rapid kVp Switch Dual Energy CT Experience

Acute Pulmonary Embolism: Imaging Techniques, Findings, Endovascular Treatment and Differential Diagnoses

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