scholarly journals Evaluation of the liver with virtual non-contrast: single institution study in 149 patients undergoing TAVR planning

2020 ◽  
Vol 93 (1106) ◽  
pp. 20190701 ◽  
Author(s):  
Kai Roman Laukamp ◽  
Simon Lennartz ◽  
Vivian Ho ◽  
Nils Große Hokamp ◽  
David Zopfs ◽  
...  
Keyword(s):  
Contrast Media ◽  
Abdominal Aorta ◽  
Region Of Interest ◽  
Hounsfield Unit ◽  
Liver Parenchyma ◽  
Arterial Phase ◽  
Single Institution ◽  
Transcatheter Aortic Valve ◽  
Spectral Detector Ct ◽  
Early Arterial Phase

Objective: To evaluate accuracy of virtual-non-contrast images (VNC) compared to true-unenhanced-images (TNC) for evaluation of liver attenuation acquired using spectral-detector CT (SDCT). Methods: 149 patients who underwent multiphase transcatheter-aortic-valve-replacement (TAVR) SDCT-examinations [unenhanced-chest (TNC), CT-angiography chest (CTA-chest, early arterial-phase) and abdomen (CTA-abdomen, additional early arterial-phase after a second injection of contrast media)] were retrospectively included. VNC of CTA-chest (VNC-chest) and CTA-abdomen (VNC-abdomen) were reconstructed and compared to TNC. Region of interest-based measurement of mean attenuation (Hounsfield unit, HU) was applied in the following regions: liver, spleen, abdominal aorta and paraspinal muscle. Results: VNC accuracy was high in the liver, spleen, abdominal aorta and muscle for abdomen-scanning. For the liver, average attenuation was 59.0 ± 9.1 HU for TNC and 72.6 ± 9.5 HU for CTA-abdomen. Liver attenuation in VNC-abdomen (59.1 ± 6.4 HU) was not significantly different from attenuation in TNC (p > 0.05). In contrast, VNC was less accurate for chest-scanning: Due to the protocol, in CTA-chest no contrast media was present in the liver parenchyma as indicated by the same attenuation in TNC (59.0 ± 9.1 HU) and CTA-chest (58.8 ± 8.9 HU, p > 0.05). Liver attenuation in VNC-chest (56.2 ± 6.4 HU, p < 0.05) was, however, significantly lower than in TNC and CTA-chest implying an artificial reduction of attenuation. Conclusion: VNC performed well in a large cohort of TAVR-examinations yielding equivalent mean attenuations to TNC; however, application of this technique might be limited when no or very little contrast media is present in parenchyma, more precisely in an early arterial-phase of the liver. Advances in knowledge: This study showed that VNC can be reliably applied in cardiac protocols when certain limitations are considered

Virtual non-contrast for evaluation of liver parenchyma and vessels: results from 25 patients using multi-phase spectral-detector CT

2019 ◽  
Vol 61 (8) ◽  
pp. 1143-1152 ◽  
Author(s):  
Kai Roman Laukamp ◽  
Vivian Ho ◽  
Verena Carola Obmann ◽  
Karin Herrmann ◽  
Amit Gupta ◽  
...  
Keyword(s):  
Portal Vein ◽  
Hepatic Artery ◽  
Abdominal Aorta ◽  
Liver Parenchyma ◽  
Image Noise ◽  
Common Hepatic Artery ◽  
Diagnostic Assessment ◽  
Arterial Phase ◽  
Spectral Detector Ct ◽  
Venous Phase

Background In abdominal imaging, contrast-enhanced computed tomography (CT) examinations are most commonly applied; however, unenhanced examinations are still needed for several clinical questions but require additional scanning and radiation exposure. Purpose To evaluate accuracy of virtual non-contrast (VNC) from arterial and venous phase spectral-detector CT (SDCT) scans compared to true-unenhanced (TNC) images for the evaluation of liver parenchyma and vessels. Material and Methods A total of 25 patients undergoing triphasic SDCT examinations were included. VNC was reconstructed from arterial and venous phases and compared to TNC images. Quantitative image analysis was performed by region of interest (ROI)-based assessment of mean and SD of attenuation (HU) in each liver segment, spleen, portal vein, common hepatic artery, and abdominal aorta. Subjectively, iodine subtraction and diagnostic assessment were rated on 5-point Likert scales. Results Attenuation and image noise measured in the liver from VNC were not significantly different from TNC (TNC: 54.6 ± 10.8 HU, VNC arterial phase: 55.7 ± 10.8 HU; VNC venous phase: 58.3 ± 10.0 HU; P > 0.05). VNC also showed accurate results regarding attenuation and image noise for spleen, portal vein, and abdominal aorta. Only iodine subtraction in the common hepatic artery in the arterial phase was insufficient which was confirmed by the subjective reading. Apart from that, subjective reading showed accurate iodine subtraction and comparable diagnostic assessment. Conclusion VNC from the arterial and venous phases were very similar to TNC yielding mostly negligible differences in attenuation, image noise, and diagnostic utility. Inadequate iodine subtraction occurred in hepatic arteries in the arterial phase.

scholarly journals Abdominal vessel depiction on virtual triphasic spectral detector CT: initial clinical experience

2021 ◽  
Author(s):  
Simon Lennartz ◽  
Kai Roman Laukamp ◽  
Yasmeen Tandon ◽  
Michelle Jordan ◽  
Nils Große Hokamp ◽  
...  
Keyword(s):  
Vena Cava ◽  
Region Of Interest ◽  
Qualitative Assessment ◽  
Arterial Phase ◽  
Phase Images ◽  
Spectral Detector Ct ◽  
Venous Phase ◽  
Significant Attenuation ◽  
Virtual Monoenergetic Images ◽  
Contrast Information

Abstract Purpose To evaluate vessel assessment in virtual monoenergetic images (VMI40keV) and virtual-non-contrast images (VNC) derived from venous phase spectral detector computed tomography (SDCT) acquisitions in comparison to arterial phase and true non-contrast (TNC) images. Methods Triphasic abdominal SDCT was performed in 25 patients including TNC, arterial and venous phase. VMI40keV and VNC were reconstructed from the venous phase and compared to conventional arterial-phase images (CIart), TNC and conventional venous-phase images (CIven). Vessel contrast and virtual contrast removal were analyzed with region-of-interest-based measurements and in a qualitative assessment. Results Quantitative analysis revealed no significant attenuation differences between TNC and VNC in arterial vessels (p-range 0.07–0.47) except for the renal artery (p = 0.011). For venous vessels, significant differences between TNC and VNC were found for all veins (p < 0.001) except the inferior vena cava (p = 0.26), yet these differences remained within a 10 HU range in most patients. No significant attenuation differences were found between CIart/VMI40keV in arterial vessels (p-range 0.06–0.86). Contrast-to-noise ratio provided by VMI40keV and CIart was equivalent for all arterial vessels assessed (p-range 0.14–0.91). Qualitatively, VMI40keV showed similar enhancement of abdominal and pelvic arteries as CIart and VNC were rated comparable to TNC. Conclusion Our study suggests that VNC and VMI40keV derived from single venous-phase SDCT offer comparable assessment of major abdominal vessels as provided by routine triphasic examinations, if no dynamic contrast information is required.

Analisis Informasi Citra Anatomi Vaskular dengan Multi Planar Reformating (MPR) dan Maximum Intensity Projection (MIP) pada Fase Early Arteri Pemeriksaan MSCT Abdomen

2017 ◽  
Vol 3 (2) ◽  
pp. 240-244
Author(s):  
Ratna Istiningrum ◽  
Fatimah Fatimah ◽  
Tri Wulanhandarini
Keyword(s):  
Maximum Intensity Projection ◽  
Arterial Phase ◽  
P Value ◽  
Post Processing ◽  
Test Analysis ◽  
Vascular Abnormalities ◽  
Kappa Test ◽  
Anatomical Image ◽  
Parametric Statistical Test ◽  
Early Arterial Phase

Background: The development in the field of image reconstruction is growing rapidly along with the development of  CT Scan. In  the early stages of  MSCT abdominal artery is usually found  various kinds of vascular abnormalities such as stenosis, aneurism and others. Post processing image techniques commonly used include MPR and MIP. The purpose of this study is to determine whether there is a difference between MPR and MIP techniques and to know which one is better between the two.Methods: This  research was  quantitative study with experimental approach. The study was conducted at Bhakti Dharma Husada Surabaya Hospital  with 15 samples by performing reconstruction on vascular anatomical image of coronal examination of  abdominal MSCT. Assessment of anatomical information data is done by 2 respondents. Data analysis was done by kappa test followed by Wilcoxon sign rank test.Result : The results showed the difference between the post-processing of MIP and MPR on the coronal stages of the early arterial phase of the abdominal MSCT examination, based on the results of  non-parametric statistical test analysis (Wilcoxon) showed  a significant value of p value = 0.001. The result of MIP mean rank value (8,46) is higher than the mean rank value of MPR (1,50), it can be known that post proceeding MIP technique on coronal phase cuts early arterial examination of abdominal MSCT produces better anatomical image information.Conclusion: On examination of abdominal MSCT in the early arterial phase should be at the time of processing the image is also done by using post-processing MIP because more clearly than the MPR.

scholarly journals Contrast agent dose reduction in computed tomography with deep learning using a conditional generative adversarial network

2021 ◽  
Author(s):  
Johannes Haubold ◽  
René Hosch ◽  
Lale Umutlu ◽  
Axel Wetter ◽  
Patrizia Haubold ◽  
...  
Keyword(s):  
Image Quality ◽  
Contrast Media ◽  
Animal Experiments ◽  
Turing Test ◽  
Dual Energy ◽  
Generative Adversarial Networks ◽  
Arterial Phase ◽  
Generative Adversarial Network ◽  
Adversarial Network ◽  
Adversarial Networks

Abstract Objectives To reduce the dose of intravenous iodine-based contrast media (ICM) in CT through virtual contrast-enhanced images using generative adversarial networks. Methods Dual-energy CTs in the arterial phase of 85 patients were randomly split into an 80/20 train/test collective. Four different generative adversarial networks (GANs) based on image pairs, which comprised one image with virtually reduced ICM and the original full ICM CT slice, were trained, testing two input formats (2D and 2.5D) and two reduced ICM dose levels (−50% and −80%). The amount of intravenous ICM was reduced by creating virtual non-contrast series using dual-energy and adding the corresponding percentage of the iodine map. The evaluation was based on different scores (L1 loss, SSIM, PSNR, FID), which evaluate the image quality and similarity. Additionally, a visual Turing test (VTT) with three radiologists was used to assess the similarity and pathological consistency. Results The −80% models reach an SSIM of > 98%, PSNR of > 48, L1 of between 7.5 and 8, and an FID of between 1.6 and 1.7. In comparison, the −50% models reach a SSIM of > 99%, PSNR of > 51, L1 of between 6.0 and 6.1, and an FID between 0.8 and 0.95. For the crucial question of pathological consistency, only the 50% ICM reduction networks achieved 100% consistency, which is required for clinical use. Conclusions The required amount of ICM for CT can be reduced by 50% while maintaining image quality and diagnostic accuracy using GANs. Further phantom studies and animal experiments are required to confirm these initial results. Key Points • The amount of contrast media required for CT can be reduced by 50% using generative adversarial networks. • Not only the image quality but especially the pathological consistency must be evaluated to assess safety. • A too pronounced contrast media reduction could influence the pathological consistency in our collective at 80%.

Heterogeneity between proximal and distal aspects of occlusive thrombi on pretreatment imaging in acute ischemic stroke

2021 ◽  
pp. 197140092110497
Author(s):  
Tetsuya Hashimoto ◽  
Takenobu Kunieda ◽  
Tristan Honda ◽  
Fabien Scalzo ◽  
Latisha K Sharma ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Ischemic Stroke ◽  
Region Of Interest ◽  
Hounsfield Unit ◽  
Distal Segment ◽  
Large Vessel Occlusion ◽  
Anterior Circulation ◽  
Vessel Occlusion ◽  
The Difference

Background The potential heterogeneity in occlusive thrombi caused by in situ propagation by secondary thrombosis after embolic occlusion could obscure the characteristics of original thrombi, preventing the clarification of a specific thrombus signature for the etiology of ischemic stroke. We aimed to investigate the heterogeneity of occlusive thrombi by pretreatment imaging. Methods Among consecutive stroke patients with acute embolic anterior circulation large vessel occlusion treated with thrombectomy, we retrospectively reviewed 104 patients with visible occlusive thrombi on pretreatment non-contrast computed tomography admitted from January 2015 to December 2018. A region of interest was set on the whole thrombus on non-contrast computed tomography under the guidance of computed tomography angiography. The region of interest was divided equally into the proximal and distal segments and the difference in Hounsfield unit densities between the two segments was calculated. Results Hounsfield unit density in the proximal segment was higher than that in the distal segment (mean difference 4.45; p < 0.001), regardless of stroke subtypes. On multivariate analysis, thrombus length was positively correlated (β = 0.25; p < 0.001) and time from last-known-well to imaging was inversely correlated (β = −0.0041; p = 0.002) with the difference in Hounsfield unit densities between the proximal and distal segments. Conclusions The difference in density between the proximal and distal segments increased as thrombi became longer and decreased as thrombi became older after embolic occlusion. This time/length-dependent thrombus heterogeneity between the two segments is suggestive of secondary thrombosis initially occurring on the proximal side of the occlusion.

scholarly journals A study on the imaging characteristics of Gold nanoparticles as a contrast agent in X-ray computed tomography

2017 ◽  
Vol 23 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Asghar Mesbahi ◽  
Fatemeh Famouri ◽  
Mohammad Johari Ahar ◽  
Maryam Olade Ghaffari ◽  
Seyed Mostafa Ghavami
Keyword(s):  
Computed Tomography ◽  
Contrast Media ◽  
Contrast Agent ◽  
Hounsfield Unit ◽  
Ct Number ◽  
Agent Based ◽  
X Ray ◽  
Imaging Characteristics ◽  
Tube Potential ◽  
X Ray Computed

AbstractAim: In the current study, some imaging characteristics of AuNPs were quantitatively analyzed and compared with two conventional contrast media (CM) including Iodine and Gadolinium by using of a cylindrical phantom.Methods: AuNPs were synthesized with the mean diameter of 16 nm and were equalized to the concentration of 0.5, 1, 2 and 4 mg/mL in the same volumes. A cylindrical phantom resembling the head and neck was fabricated and drilled to contain small tubes filled with Iodine, Gadolinium, and AuNPs as contrast media. The phantom was scanned in different exposure techniques and CT numbers of three studied contrast media inside test tubes were measured in terms of Hounsfield Unit (HU). The imaging parameters of the noise and contrast to noise ratios (CNR) were calculated for all studied CMs.Results: AuNPs showed 128% and 166% higher CT number in comparison with Iodine and Gadolinium respectively. Also, Iodine had a greater CT number than Gadolinium for the same exposure techniques and concentration. The maximum CT number for AuNPs and studied contrast materials was obtained at the highest mAs and the lowest tube potential. The maximum CT number were 1033±11 (HU) for AuNP, 565±10 (HU) for Iodine, 458±11 for Gadolinium. Moreover, the maximum CNRs of 433±117, 203±53, 145±37 were found for AuNPs, Iodine and Gadolinium respectively.Conclusion: The contrast agent based on AuNPs showed higher imaging quality in terms of contrast and noise relative to other iodine and gadolinium based contrast media in X-ray computed tomography. Application of the AuNPs as a contrast medium in x-ray CT is recommended.

Role of spectral-detector CT in reduction of artifacts from contrast media in axillary and subclavian veins: single institution study in 50 patients

2019 ◽  
Vol 61 (4) ◽  
pp. 450-460 ◽  
Author(s):  
Kai Roman Laukamp ◽  
Amit Gupta ◽  
Nils Große Hokamp ◽  
Verena Carola Obmann ◽  
Frank Philipp Graner ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Contrast Media ◽  
Intraclass Correlation ◽  
Ct Images ◽  
Diagnostic Assessment ◽  
Surrounding Soft Tissue ◽  
Iodinated Contrast ◽  
Spectral Detector Ct ◽  
Virtual Monoenergetic Images ◽  
Monoenergetic Images

Background In CT imaging, a high concentration of iodinated contrast media in axillary and subclavian veins after brachial application can cause perivenous artifacts impairing diagnostic assessment of local vascular structures and soft tissue. Purpose To investigate reduction of perivenous hypo- and hyperattenuating artifacts of the axillary and subclavian veins using virtual monoenergetic images (VMI) in comparison to conventional CT images (CI), acquired on spectral-detector CT. Material and Methods 50 spectral-detector CT datasets of patients with perivenous artifacts from contrast media were included in this retrospective, institutional review board-approved study. CT images and virtual monoenergetic images (range 40–200 keV, 10-keV increments) were reconstructed from the same scans. Quantitative analysis was performed by region of interest-based assessment of mean attenuation (HU) and standard deviation in most pronounced hypo- and hyperdense artifacts and artifact-impaired arteries as well as muscle. Visually, artifact reduction, assessment of vessels, and surrounding soft tissue were rated on 5-point Likert-scales by two radiologists. Results In comparison to CT images, virtual monoenergetic images of ≥90 keV showed a significant reduction of hypo- and hyperattenuating artifacts (hypodense: CI -220.0±171.2 HU; VMI130keV -13.4±49.1 HU; hyperdense: CI 274.6±184.4 HU; VMI130keV 24.2±84.9 HU; P<0.001). Subjective analysis confirmed that virtual-monoenergetic images of ≥100 keV significantly reduced artifacts (hypodense: CI 2[1–3]; VMI130keV 5[4–5], hyperdense: CI 2[1–4]; VMI130keV 5[5–5], P<0.001) and improved diagnostic assessment. Best results for diagnostic assessment were noted for virtual monoenergetic images at 130 keV. Overcorrection of artifacts was observed at higher keV values. Interrater agreement was excellent for each evaluation and keV value (intraclass correlation coefficient 0.89). Conclusion Higher keV virtual monoenergetic images yielded significant reduction of contrast media artifacts and led to improved assessment of vessels and surrounding soft tissue. Recommended keV values for best diagnostic assessment are in the range of 100–160 keV.

scholarly journals Adequacy of an early arterial phase low-volume contrast protocol in 64-detector computed tomography angiography for aortoiliac aneurysms

2008 ◽  
Vol 47 (3) ◽  
pp. 492-498 ◽  
Author(s):  
Nicolas Diehm ◽  
Constantino Pena ◽  
James F. Benenati ◽  
Athanassios I. Tsoukas ◽  
Barry T. Katzen
Keyword(s):  
Computed Tomography ◽  
Computed Tomography Angiography ◽  
Arterial Phase ◽  
Low Volume ◽  
Early Arterial Phase

scholarly journals Correlation between clot density and recanalization success or stroke etiology in acute ischemic stroke patients

2017 ◽  
Vol 23 (3) ◽  
pp. 274-278 ◽  
Author(s):  
Manoj Jagani ◽  
David F Kallmes ◽  
Waleed Brinjikji
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Region Of Interest ◽  
Hounsfield Unit ◽  
Stent Retriever ◽  
Large Artery ◽  
Stroke Etiology ◽  
Significant Difference ◽  
The Mean ◽  
Axial Slice

Background Predicting recanalization success for patients undergoing endovascular treatment for acute ischemic stroke is of significant interest. Studies have previously correlated the success of recanalization with the density of the clot. We evaluated clot density and its relationship to revascularization success and stroke etiology. Methods We conducted a retrospective review of 118 patients undergoing intra-arterial therapy for acute ischemic stroke. Mean and maximum thrombus density was measured by drawing a circular region of interest on an axial slice of a non-contrast computed tomography scan. T-tests were used to compare clot density to recanalization success or to stroke etiology, namely large artery atherosclerosis and cardioembolism. Recanalization success was compared in four device groups: aspiration, stent retriever, aspiration and stent retriever, and all other. Results There was no significant difference in the mean clot density in patients with successful ( n = 80) versus unsuccessful recanalization ( n = 38, 50.1 ± 7.4 Hounsfield unit (HU) vs. 53 ± 12.7 HU; P = 0.17). Comparing the large artery thromboembolism ( n = 35) to the cardioembolic etiology group ( n = 56), there was no significant difference in mean clot density (51.5 ± 7.7 HU vs. 49.7 ± 8.5 HU; P = 0.31). A subgroup analysis of middle cerebral artery occlusions ( n = 65) showed similar, non-statistically significant differences between groups. There was no difference in the rate of recanalization success in patients with a mean clot density greater than 50 HU or less than 50 HU in each of the four device groups. Conclusions There was no relationship between clot density and revascularization success or stroke etiology in our study. More research is needed to determine if clot density can predict recanalization rates or indicate etiology.

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