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Value of low-keV virtual monoenergetic plus dual-energy computed tomographic imaging for detection of acute pulmonary embolism. PLoS One 2022; 17:e0277060. [DOI: 10.1371/journal.pone.0277060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 10/19/2022] [Indexed: 11/13/2022] Open
Abstract
Objective
To compare diagnostic values between the 40 keV virtual monoenergetic plus (40 keV VMI+) dual source dual energy computed tomography (DSDECT) pulmonary angiography images and the standard mixed (90 and 150 kV) images for the detection of acute pulmonary embolism (PE).
Methods
Chest DSDECTs of 64 patients who were suspected of having acute PE were retrospectively reviewed by two independent reviewers. The assessments of acute PE of all patients on a per-location basis were compared between the 40 keV VMI+ and the standard mixed datasets (reference standard) with a two-week interval.
Results
This study consisted of 64 patients (33 women and 31 men; mean age, 60.2 years; range 18–90 years), with a total of 512 locations. The interobserver agreement (Kappa) for detection of acute PE using the 40 keV VMI+ images and the standard mixed CT images were 0.7478 and 0.8750 respectively. The area under receiver operating characteristics (AuROC) for diagnosis of acute PE using the 40 keV VMI+ was 0.882. Four locations (0.78%) revealed a false negative result. Hypodense filling defects were identified in twelve locations (1.95%) in the 40 keV VMI+ images but had been interpreted as a negative study in the standard mixed CT images. The repeated reviews revealed that each location contained a hypodense filling defect but was overlooked on the standard mixed CT images.
Conclusions
Low-energy VMI + DSDECT images have beneficial in improving the diagnostic value of acute PE in doubtful or disregarded standard mixed images.
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Cantarinha A, Bassil C, Savignac A, Devilder M, Maxwell F, Crézé M, Purcell YM, Bellin MF, Meyrignac O, Dillenseger JP. "Triple low" free-breathing CTPA protocol for patients with dyspnoea. Clin Radiol 2022; 77:e628-e635. [PMID: 35688771 DOI: 10.1016/j.crad.2022.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/09/2022] [Indexed: 11/03/2022]
Abstract
AIM To assess the performance of a "triple-low" free-breathing protocol for computed tomography pulmonary angiography (CTPA) evaluated on patients with dyspnoea and suspected pulmonary embolism and discuss its application in routine clinical practice for the study of the pulmonary parenchyma and vasculature. MATERIAL AND METHODS This study was conducted on a selected group of dyspnoeic patients referred for CTPA. The protocol was designed using fast free-breathing acquisition and a small, fixed volume (35 ml) of contrast agent in order to achieve a low-exposure dose. For each examination, radiodensity of the pulmonary trunk and ascending aorta, and the dose-length product (DLP) were recorded. A qualitative analysis was performed of pulmonary arterial enhancement and the pulmonary parenchyma. RESULTS This study included 134 patients. Contrast enhancement of the pulmonary arteries (409 ± 159 HU) was systematically >250 HU. The duration of acquisition ranged from 0.9 to 1.3 seconds for free-breathing imaging. The mean DLP was in the range of low-dose chest CT acquisitions (145 ± 73 mGy·cm). The analysis was deemed optimal in 90% (120/134) of cases for the pulmonary parenchyma. Sixty-nine per cent (92/134) of cases demonstrated homogeneous enhancement of the pulmonary arteries to the subsegmental level. Only 6% (8/134) of examinations were considered uninterpretable. CONCLUSION The present "triple-low" CTPA protocol allows convenient analysis of the pulmonary parenchyma and arteries without hindrance by respiratory motion artefacts in dyspnoeic patients.
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Affiliation(s)
- A Cantarinha
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - C Bassil
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - A Savignac
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - M Devilder
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - F Maxwell
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - M Crézé
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France; BioMaps, Université Paris-Saclay, Hôpital Kremlin-Bicêtre, Le Kremlin-Bicêtre, France
| | - Y M Purcell
- Hôpital Fondation Adolphe de Rothschild, Paris, France
| | - M-F Bellin
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France; BioMaps, Université Paris-Saclay, Hôpital Kremlin-Bicêtre, Le Kremlin-Bicêtre, France
| | - O Meyrignac
- Service de Radiologie Générale Adulte, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, Département Médico Universitaire Smart Imaging, Assistance Publique des Hôpitaux de Paris, Le Kremlin-Bicêtre, France; BioMaps, Université Paris-Saclay, Hôpital Kremlin-Bicêtre, Le Kremlin-Bicêtre, France
| | - J-P Dillenseger
- Faculté de Médecine, Maïeutique, et Sciences de la Santé, Université de Strasbourg, Strasbourg, France; ICube-UMR 7357, CNRS, Université de Strasbourg, Strasbourg, France.
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Ahuja J, Palacio D, Jo N, Strange CD, Shroff GS, Truong MT, Wu CC. Pitfalls in the imaging of pulmonary embolism. Semin Ultrasound CT MR 2022; 43:221-229. [PMID: 35688533 DOI: 10.1053/j.sult.2022.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Pulmonary embolism (PE) can present with a wide spectrum of clinical symptoms that can overlap considerably with other cardiovascular diseases. To avoid PE related morbidity and mortality, it is vital to identify this disease accurately and in a timely fashion. Several clinical criteria have been developed to standardize the diagnostic approach for patients with suspected PE. Computed tomographic pulmonary angiogram has significantly improved the detection of pulmonary embolism and is considered the imaging modality of choice to diagnose this disease. However, there are several potential pitfalls associated with this modality which can make diagnosis of PE challenging. In this review, we will discuss various pitfalls routinely encountered in the diagnostic work up of patients with suspected PE, approaches to mitigate these pitfalls and incidental pulmonary embolism.
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Affiliation(s)
- Jitesh Ahuja
- Department of Thoracic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX.
| | - Diana Palacio
- Department of Radiology, The University of Texas Medical Branch, UTMB. Galveston TX
| | - Nahyun Jo
- Department of Radiology, The University of Texas Medical Branch, UTMB. Galveston TX
| | - Chad D Strange
- Department of Thoracic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Girish S Shroff
- Department of Thoracic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Mylene T Truong
- Department of Thoracic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Carol C Wu
- Department of Thoracic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX
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Debnath J, Sharma V. Diagnosing pulmonary thromboembolism: Concerns and controversies. Med J Armed Forces India 2022; 78:17-23. [PMID: 35035039 PMCID: PMC8737094 DOI: 10.1016/j.mjafi.2021.05.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 05/24/2021] [Indexed: 01/03/2023] Open
Abstract
Pulmonary thromboembolism (PTE) is an important cause of mortality/morbidity even today despite advancement in clinical understanding as well as diagnostic facilities. Clinical diagnosis of PTE is often challenging because of nonspecific sign/symptoms. Adherence to clinical decision-making protocols and appropriate use of diagnostic modalities like computed tomography pulmonary angiography can resolve the diagnostic dilemma in most cases and help in the overall management of PTE. This article deals with various concerns as well as controversies surrounding accurate diagnosis of PTE as on date.
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Affiliation(s)
- Jyotindu Debnath
- Consultant, Professor & Head (Radiodiagnosis), Army Hospital (R&R), Delhi Cantt, India,Corresponding author.
| | - Vivek Sharma
- Professor (Radiodiagnosis), Bharati Vidyapeeth Medical College, Pune, India
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Li K, Li Y, Qi Z, Garrett JW, Grist TM, Chen GH. Quantitative lung perfusion blood volume using dual energy CT-based effective atomic number (Z eff ) imaging. Med Phys 2021; 48:6658-6672. [PMID: 34520066 DOI: 10.1002/mp.15227] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 08/31/2021] [Accepted: 09/06/2021] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Iodine material images (aka iodine basis images) generated from dual energy computed tomography (DECT) have been used to assess potential perfusion defects in the pulmonary parenchyma. However, iodine material images do not provide the needed absolute quantification of the pulmonary blood pool, as materials with effective atomic numbers (Zeff ) different from those of basis materials may also contribute to iodine material images, thus confounding the quantification of perfusion defects. PURPOSE (i) To demonstrate the limitations of iodine material images in pulmonary perfusion defect quantification and (ii) to develop and validate a new quantitative biomarker using effective atomic numbers derived from DECT images. METHODS The quantitative relationship between the perfusion blood volume (PBV) in pulmonary parenchyma and the effective atomic number (Zeff ) spatial distribution was studied to show that the desired quantitative PBV maps are determined by the spatial maps of Zeff as PB V Z eff ( x ) = a Z eff β ( x ) + b , where a, b, and β are three constants. Namely, quantitative PB V Z eff is determined by Zeff images instead of the iodine basis images. Perfusion maps were generated for four human subjects to demonstrate the differences between conventional iodine material image-based PBV (PBViodine ) derived from two-material decompositions and the proposed PB V Z eff method. RESULTS Among patients with pulmonary emboli, the proposed PB V Z eff maps clearly show the perfusion defects while the PBViodine maps do not. Additionally, when there are no perfusion defects present in the derived PBV maps, no pulmonary emboli were diagnosed by an experienced thoracic radiologist. CONCLUSION Effective atomic number-based quantitative PBV maps provide the needed sensitive and specific biomarker to quantify pulmonary perfusion defects.
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Affiliation(s)
- Ke Li
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Radiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Yinsheng Li
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Zhihua Qi
- Department of Radiology, Henry Ford Health System, Detroit, Michigan, USA
| | - John W Garrett
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Radiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Thomas M Grist
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Radiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Guang-Hong Chen
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Radiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Rose S, Viggiano B, Bour R, Bartels C, Kanne JP, Szczykutowicz TP. Applying a New CT Quality Metric in Radiology: How CT Pulmonary Angiography Repeat Rates Compare Across Institutions. J Am Coll Radiol 2021; 18:962-968. [PMID: 33741373 DOI: 10.1016/j.jacr.2021.02.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To quantify overall CT repeat and reject rates at five institutions and investigate repeat and reject rates for CT pulmonary angiography (CTPA). METHODS In this retrospective study, we apply an automated repeat rate analysis algorithm to 103,752 patient examinations performed at five institutions from July 2017 to August 2019. The algorithm identifies repeated scans for specific scanner and protocol combinations. For each institution, we compared repeat rates for CTPA to all other CT protocols. We used logistic regression and analysis of deviance to compare CTPA repeat rates across institutions and size-based protocols. RESULTS Of 103,752 examinations, 1,447 contained repeated helical scans (1.4%). Overall repeat rates differed across institutions (P < .001) ranging from 0.8% to 1.8%. Large-patient CTPA repeat rates ranged from 3.0% to 11.2% with the odds (95% confidence intervals) of a repeat being 4.8 (3.5-6.6) times higher for large- relative to medium-patient CTPA protocols. CTPA repeat rates were elevated relative to all other CT protocols at four of five institutions, with strong evidence of an effect at two institutions (P < .001 for each; odds ratios: 2.0 [1.6-2.6] and 6.2 [4.4-8.9]) and somewhat weaker evidence at the others (P = .005 and P = 0.011; odds ratios: 2.2 [1.3-3.8] and 3.7 [1.5-9.1], respectively). Accounting for size-based protocols, CTPA repeat rates differed across institutions (P < .001). DISCUSSION The results indicate low overall repeat rates (<2%) with CTPA rates elevated relative to other protocols. Large-patient CTPA rates were highest (eg, 11.2% at one institution). Differences in repeat rates across institutions suggest the potential for quality improvement.
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Affiliation(s)
- Sean Rose
- Department of Medical Physics, University of Wisconsin Madison, Madison, Wisconsin
| | - Ben Viggiano
- Department of Radiology, University of Wisconsin Madison, Madison, Wisconsin
| | - Robert Bour
- Department of Radiology, University of Wisconsin Madison, Madison, Wisconsin
| | - Carrie Bartels
- Department of Radiology, University of Wisconsin Madison, Madison, Wisconsin
| | - Jeffery P Kanne
- Vice Chair of Quality and Safety, Department of Radiology, University of Wisconsin, Madison, Wisconsin
| | - Timothy P Szczykutowicz
- Department of Medical Physics, University of Wisconsin Madison, Madison, Wisconsin; Department of Radiology, University of Wisconsin Madison, Madison, Wisconsin; Department of Biomedical Engineering, University of Wisconsin Madison, Madison, Wisconsin.
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Optimizing Pulmonary Embolism Computed Tomography in the Age of Individualized Medicine: A Prospective Clinical Study. Invest Radiol 2019; 53:306-312. [PMID: 29438139 DOI: 10.1097/rli.0000000000000443] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE The aim of the study was to simultaneously optimize contrast media (CM) injection and scan parameters for the individual patient during computed tomography pulmonary angiography (CTPA). METHODS In this study (NCT02611115), 235 consecutive patients suspected of having pulmonary embolism were prospectively enrolled. Automated kV selection software on a third-generation multidetector computed tomography adapted tube voltage to the individual patient, based on scout scans. The contrast injection protocol was adapted to both patient body weight and kV-setting selection via a predefined formula, based on previous research. Injection data were collected from a contrast media and radiation dose monitoring software. Attenuation was measured in Hounsfield units (HU) in the pulmonary trunk (PT); attenuation values 200 HU or greater were considered diagnostic. Subjective image quality was assessed by using a 4-point Likert scale at the level of the PT, lobar, segmental, and subsegmental arteries. Results between groups were reported as mean ± SD. RESULTS Two hundred twenty-two patients (94%) were scanned at a kV setting below 100 kV: n = 108 for 70 kV, n = 82 for 80 kV, and n = 32 for 90 kV. Mean CM bolus volume (in milliliters) and total iodine load (in grams of iodine) for 70 to 90 kV were as follows: 24 ± 3 mL and 7 ± 1 g I, 29 ± 4 mL and 9 ± 2 g I, and 38 ± 4 mL and 11 ± 1 g I, respectively. Mean flow rates (in milliliters per second) and iodine delivery rates (in grams of iodine per second) were 3.0 ± 0.4 mL/s and 0.9 ± 0.1 g I/s (70 kV), 3.6 ± 0.4 mL/s and 1.0 ± 0.1 g I/s (80 kV), and 4.7 ± 0.5 mL/s and 1.3 ± 0.1 g I/s (90 kV). Mean radiation doses were 1.3 ± 0.3 mSv at 70 kV, 1.7 ± 0.4 mSv at 80 kV, and 2.2 ± 0.6 mSv at 90 kV. Mean vascular attenuation in the PT for each kV group was as follows: 397 ± 101 HU for 70 kV, 398 ± 96 HU for 80 kV, and 378 ± 100 HU for 90 kV, P = 0.59. Forty-six patients (21%) showed pulmonary embolism on the CTPA. One scan (90 kV) showed nondiagnostic segmental pulmonary arteries, and 5% of subsegmental arteries were of nondiagnostic image quality. All other segments were considered diagnostic-excellent subjective image quality. CONCLUSIONS Simultaneously optimizing both CM injections and kV settings to the individual patient in CTPA results in diagnostic attenuation with on average 24 to 38 mL of CM volume and a low radiation dose for most patients. This individualized protocol may help overcome attenuation-variation problems between patients and kV settings in CTPA.
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Martin SS, van Assen M, Griffith LP, De Cecco CN, Varga-Szemes A, Bauer MJ, Wichmann JL, Vogl TJ, Schoepf UJ. Dual-Energy CT Pulmonary Angiography: Quantification of Disease Burden and Impact on Management. CURRENT RADIOLOGY REPORTS 2018. [DOI: 10.1007/s40134-018-0297-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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9
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Pitfalls in the Diagnosis of Acute Pulmonary Embolism on Computed Tomography: Common Pathologic and Imaging Mimics. CURRENT RADIOLOGY REPORTS 2018. [DOI: 10.1007/s40134-018-0273-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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10
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Virtual Monoenergetic Imaging and Iodine Perfusion Maps Improve Diagnostic Accuracy of Dual-Energy Computed Tomography Pulmonary Angiography With Suboptimal Contrast Attenuation. Invest Radiol 2017; 52:659-665. [DOI: 10.1097/rli.0000000000000387] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Tromeur C, van der Pol LM, Klok FA, Couturaud F, Huisman MV. Pitfalls in the diagnostic management of pulmonary embolism in pregnancy. Thromb Res 2017; 151 Suppl 1:S86-S91. [PMID: 28262243 DOI: 10.1016/s0049-3848(17)30075-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Women are at increased risk of venous thromboembolism (VTE) during pregnancy and VTE remains one of the main causes of maternal mortality in developed countries (Konstantinides SV, et al. Eur Heart J 2014; 35(43):3033-69, 69a-69k). Although an accurate diagnosis of acute pulmonary embolism (PE) in pregnant patients is thus of crucial importance, the diagnostic management of suspected PE is challenging for this specific patient category. As D-dimer levels increase physiologically throughout pregnancy, the optimal D-dimer threshold to rule out PE during pregnancy remains unknown. Available clinical decision rules, such as the Wells score and the revised Geneva rule, have not been evaluated in pregnant patients. Also, although ventilation-perfusion (V-Q) lung scan and computed tomography pulmonary angiography (CTPA) can be used in the pregnant population, both modalities have disadvantages of radiation exposure to both mother and foetus. Because of these uncertainties, clinical guidelines provide contradicting recommendations with weak levels of evidence. In this review, we illustrate these dilemmas and provide practice recommendation for the diagnostic management of suspected PE in pregnancy using two real-life patient cases.
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Affiliation(s)
- Cécile Tromeur
- Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The Netherlands; Groupe d'Etude de la Thrombose de Bretagne Occidentale, Equipe d'Accueil 3878, Department of Internal Medicine and Chest Diseases, Brest, France; Centre d'Investigation Clinique INSERM 1412, Groupe d'Investigation et de Recherche Clinique, Brittany University of Brest, Brest, France
| | - Liselotte M van der Pol
- Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The Netherlands
| | - Frederikus A Klok
- Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The Netherlands
| | - Francis Couturaud
- Groupe d'Etude de la Thrombose de Bretagne Occidentale, Equipe d'Accueil 3878, Department of Internal Medicine and Chest Diseases, Brest, France; Centre d'Investigation Clinique INSERM 1412, Groupe d'Investigation et de Recherche Clinique, Brittany University of Brest, Brest, France
| | - Menno V Huisman
- Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The Netherlands.
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Prognostic value of computed tomography in acute pulmonary thromboembolism. RADIOLOGIA 2016; 58:391-403. [PMID: 27492053 DOI: 10.1016/j.rx.2016.06.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/18/2016] [Accepted: 06/23/2016] [Indexed: 12/14/2022]
Abstract
In addition to being the standard reference for the diagnosis of acute pulmonary thromboembolism, CT angiography of the pulmonary arteries can also provide valuable information about the patient's prognosis. Although which imaging findings are useful for prognosis remains controversial, signs of right ventricular dysfunction on CT are now included in clinical algorithms for the management of pulmonary thromboembolism. However, the optimal method for obtaining these measurements while maintaining a balance between the ease of use necessary to include their evaluation in our daily activity and the loss of precision in its predictive capacity remains to be determined. Moreover, other variables associated with pulmonary thromboembolism that often go unobserved can complement the prognostic information we can offer to clinicians. This review aims to clarify some of the more controversial aspects related to the prognostic value of CT in patients with pulmonary embolisms according to the available evidence. Knowing which variables are becoming more important in the prognosis, how to detect them, and why it is important to include them in our reports will help improve the management of patients with pulmonary embolism.
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14
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Trad HS, Boasquevisque GS, Giacometti TR, Trad CY, Zoghbi Neto OS, Trad CS. Pulmonary 64-MDCT angiography with 50 mL of iodinated contrast material in an unselected patient population: a feasible protocol. Radiol Bras 2016; 49:75-8. [PMID: 27141128 PMCID: PMC4851474 DOI: 10.1590/0100-3984.2014.0115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Objective To propose a protocol for pulmonary angiography using 64-slice multidetector
computed tomography (64-MDCT) with 50 mL of iodinated contrast material, in
an unselected patient population, as well as to evaluate vascular
enhancement and image quality. Materials and Methods We evaluated 29 patients (22-86 years of age). The body mass index ranged
from 19.0 kg/m2 to 41.8 kg/m2. Patients underwent
pulmonary CT angiography in a 64-MDCT scanner, receiving 50 mL of iodinated
contrast material via venous access at a rate of 4.5 mL/s. Bolus tracking
was applied in the superior vena cava. Two experienced radiologists assessed
image quality and vascular enhancement. Results The mean density was 382 Hounsfield units (HU) for the pulmonary trunk; 379
and 377 HU for the right and left main pulmonary arteries, respectively; and
346 and 364 HU for the right and left inferior pulmonary arteries,
respectively. In all patients, subsegmental arteries were analyzed. There
were streak artifacts from contrast material in the superior vena cava in
all patients. However, those artifacts did not impair the image
analysis. Conclusion Our findings suggest that pulmonary angiography using 64-MDCT with 50 mL of
iodinated contrast can produce high quality images in unselected patient
populations.
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Moradi M, Monfared LJ. Qualitative evaluation of pulmonary CT angiography findings in pregnant and postpartum women with suspected pulmonary thromboembolism. JOURNAL OF RESEARCH IN MEDICAL SCIENCES 2016; 20:1088-93. [PMID: 26941814 PMCID: PMC4755097 DOI: 10.4103/1735-1995.172834] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background: Considering the importance of using more appropriate imaging technique for accurate diagnosis of pulmonary thromboembolism (PTE) with less side effects, we aimed to evaluate the quality of pulmonary 64-multidetector computed tomographic (MDCT) angiography in pregnant and postpartum women with suspected PTE in Isfahan. Materials and Methods: In this descriptive study, radiological findings of pregnant and postpartum women with suspected PTE who underwent pulmonary 64-MDCT angiography were evaluated. Prevalence of PTE in pregnant and postpartum women, mean of pulmonary arteries density for right and left pulmonary arteries, and their lobar and segmental branches, diagnostic quality of the pulmonary arteries density and their scoring, frequency of diagnostic and nondiagnostic images, mean of radiation dose and mean of bolus time, and the correlation between the quality of the vascular density with the peak density of the pulmonary artery were determined. Results: In this study, 44 pregnant and postpartum women with suspected PTE were selected. The overall prevalence of PTE was 9.1% (4/44). PTE was diagnosed in 1 (3.7%) pregnant and 3 (17.5%) postpartum women (P = 0.14). Mean density of pulmonary trunk was 278.81± 108.16 Hounsfield unit (HU) and 308.41 ± 59.30 HU in pregnant and postpartum women, respectively. Mean of bolus timing, kilovoltage peak (kVp), tube current, and dose length product (DLP) were 12.53 ± 2.36 s, 105.22± 45.71 milliamperage (MA), 382.9 ± 173.5 MA, and 317.98 ± 78.92 mGy/cm, respectively. The rate of nondiagnostic images was 4.5%. Conclusion: Our findings indicated that pulmonary 64-MDCT angiography is an appropriate imaging method for diagnosing PTE in pregnant and postpartum women with suspected PTE. It seems that, using fast CT systems (64-MDCT), in accordance with high flow rate, high contrast medium concentration and low kVp could explain the obtained appropriate quality of images more efficiently than computed tomographic pulmonary angiography (CTPA).
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Affiliation(s)
- Maryam Moradi
- Department of Radiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Leyla Jalali Monfared
- Department of Radiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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Exponentially Decelerated Contrast Media Injection Rate Combined With a Novel Patient-Specific Contrast Formula Reduces Contrast Volume Administration and Radiation Dose During Computed Tomography Pulmonary Angiography. J Comput Assist Tomogr 2016; 40:370-4. [DOI: 10.1097/rct.0000000000000371] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Optimizing computed tomography pulmonary angiography using right atrium bolus monitoring combined with spontaneous respiration. Eur Radiol 2015; 25:2541-6. [PMID: 25850891 DOI: 10.1007/s00330-015-3664-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 02/01/2015] [Accepted: 02/12/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES CT pulmonary angiography (CTPA) aims to provide pulmonary arterial opacification in the absence of significant pulmonary venous filling. This requires accurate timing of the imaging acquisition to ensure synchronization with the peak pulmonary artery contrast concentration. This study was designed to test the utility of right atrium (RA) monitoring in ensuring optimal timing of CTPA acquisition. METHODS Sixty patients referred for CTPA were divided into two groups. Group A (n = 30): CTPA was performed using bolus triggering from the pulmonary trunk, suspended respiration and 70 ml of contrast agent (CA). Group B (n = 30): CTPA image acquisition was triggered using RA monitoring with spontaneous respiration and 40 ml of CA. Image quality was compared. RESULTS Subjective image quality, average CT values of pulmonary arteries and density difference between artery and vein pairs were significantly higher whereas CT values of pulmonary veins were significantly lower in group B (all P < 0.05). There was no significant difference between the groups in the proportion of subjects where sixth grade pulmonary arteries were opacified (P > 0.05). CONCLUSIONS RA monitoring combined with spontaneous respiration to trigger image acquisition in CTPA produces optimal contrast enhancement in pulmonary arterial structures with minimal venous filling even with reduced doses of CA. KEY POINTS • Bolus tracking (BT) with pulmonary trunk monitoring is widely used in CTPA. • Pulmonary venous contamination is a disadvantage of BT due to transition delay time. • Right atrium monitoring with spontaneous respiration can optimize CTPA. • It produces optimal contrast enhancement in pulmonary arteries with minimal venous filling. • The contrast dose was significantly reduced.
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Palacio D, Benveniste MF, Betancourt-Cuellar SL, Gladish GW. Multidetector computed tomography pulmonary angiography pitfalls in the evaluation of pulmonary embolism with emphasis in technique. Semin Roentgenol 2015; 50:217-25. [PMID: 26002242 DOI: 10.1053/j.ro.2015.01.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Diana Palacio
- Department of Medical Imaging, The University of Arizona College of Medicine, Tucson, Arizona USA; Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, TX.
| | - Marcelo F Benveniste
- Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, TX
| | | | - Gregory W Gladish
- Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, TX
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Abstract
To characterize the clinical features of oncology patients presenting with shortness of breath mistakenly diagnosed at first with pulmonary emboli, but later found instead to have extrinsic compression of the pulmonary artery or its tributaries by tumor. Medical charts and computed tomography (CT) angiographies of these patients were reviewed retrospectively. In a 7-year period, 11 patients from a single institute were identified. Five patients were excluded as they had a pleural and pericardial effusion that by itself could result in dyspnea. All had varied solid tumors and none had lymphoma. In three of six patients, an increased ratio between right and left ventricle was detected by CT angiography; however, in contradistinction to patients with pulmonary emboli, this was not found to be associated with short survival. The term 'pseudo pulmonary emboli' is suggested to describe this phenomenon. Anticoagulant treatment to avoid in-situ pulmonary artery thrombosis may be considered; however, misdiagnosis of pulmonary embolism may delay the appropriate treatment with chemotherapy, biological therapy, and radiotherapy.
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Hochhegger B, Alves GRT, Chaves M, Moreira AL, Kist R, Watte G, Moreira JS, Irion KL, Marchiori E. Interobserver agreement between radiologists and radiology residents and emergency physicians in the detection of PE using CTPA. Clin Imaging 2014; 38:445-447. [PMID: 24667043 DOI: 10.1016/j.clinimag.2014.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/19/2014] [Accepted: 03/03/2014] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To assess interobserver agreement between thoracic radiologists, radiology residents, and emergency physicians in diagnosing pulmonary embolism (PE). MATERIALS AND METHODS Emergency physicians, radiology residents, and thoracic radiologists evaluated 123 computed tomography pulmonary angiography images. Interobserver agreement was analysed using kappa statistics. RESULTS Very good agreements were observed between thoracic radiologists and radiology residents (0.81 and 0.82). Fair and moderate agreements (0.39 and 0.42) were demonstrated between emergency physicians and thoracic radiologists. CONCLUSIONS Important differences in interobserver agreement were found, with emergency physicians tending to overdiagnose PE.
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Affiliation(s)
- Bruno Hochhegger
- Medical Imaging Research Lab, Federal University of Health Sciences of Porto Alegre, Porto Alegre, 90020-090, Brazil
| | - Giordano R T Alves
- Post-graduation Program in Medicine (Radiology) at the Federal University of Rio de Janeiro, 21941-901, Brazil.
| | - Marcus Chaves
- Divison of Pulmonary Medicine, Santa Casa Healthcare Complex of Porto Alegre, Porto Alegre, 90020-090, Brazil
| | - Ana Luiza Moreira
- Divison of Pulmonary Medicine, Santa Casa Healthcare Complex of Porto Alegre, Porto Alegre, 90020-090, Brazil
| | - Renato Kist
- Medical Imaging Research Lab, Federal University of Health Sciences of Porto Alegre, Porto Alegre, 90020-090, Brazil
| | - Guilherme Watte
- Medical Imaging Research Lab, Federal University of Health Sciences of Porto Alegre, Porto Alegre, 90020-090, Brazil
| | - José S Moreira
- Divison of Pulmonary Medicine, Santa Casa Healthcare Complex of Porto Alegre, Porto Alegre, 90020-090, Brazil
| | - Klaus L Irion
- Department of Radiology, Liverpool Heart and Chest Hospital NHS Foundation Trust, Liverpool, L14 3PE, UK
| | - Edson Marchiori
- Department of Radiology, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-901, Brazil
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Yee S, Scalzetti EM. Measurement of cardiac output from dynamic pulmonary circulation time CT. Med Phys 2014; 41:061904. [DOI: 10.1118/1.4875676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Guimaraes MD, Bitencourt AGV, Marchiori E, Chojniak R, Gross JL, Kundra V. Imaging acute complications in cancer patients: what should be evaluated in the emergency setting? Cancer Imaging 2014; 14:18. [PMID: 25609051 PMCID: PMC4331823 DOI: 10.1186/1470-7330-14-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 02/13/2014] [Indexed: 12/13/2022] Open
Abstract
Increased incidence world-wide of cancer and increased survival has also resulted in physicians seeing more complications in patients with cancer. In many cases, complications are the first manifestations of the disease. They may be insidious and develop over a period of months, or acute and manifest within minutes to days. Imaging examinations play an essential role in evaluating cancer and its complications. Plain radiography and ultrasonography (US) are generally performed initially in an urgent situation due to their wide availability, low cost, and minimal or no radiation exposure. However, depending on a patient's symptoms, evaluation with cross-sectional imaging methods such as computed tomography (CT) and magnetic resonance imaging (MRI) is often necessary. In this review article, we discuss some of the most important acute noninfectious oncological complications for which imaging methods play an essential role in diagnosis.
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Evaluation of imaging quality of pulmonary 64-MDCT angiography in pregnancy and puerperium. AJR Am J Roentgenol 2014; 202:60-4. [PMID: 24370129 DOI: 10.2214/ajr.12.9917] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The aim of this study was to quantitatively and qualitatively evaluate pulmonary 64-MDCT angiography image quality in pregnancy and puerperium, compared with female nonpregnant control subjects. MATERIALS AND METHODS The study group comprised 124 consecutive pregnant and postpartum women and 124 female nonpregnant control subjects who presented with suspected pulmonary embolism. The individual studies were evaluated for subjective and objective diagnostic quality. RESULTS Objective measurements of the arterial enhancement in the pulmonary trunk and left and right pulmonary arteries found that there was no statistically significant difference in attenuation values between the pregnant and puerperium group and the control group for pulmonary artery opacification. The mean attenuation in the pulmonary trunk was 270.54 HU in the pregnant group, 277.53 HU in the puerperium group, and 293.90 HU in the control group. CONCLUSION We found no significant difference in diagnostic quality of pulmonary CT angiography using MDCT between the study and control groups. The use of MDCT acquisition, faster injection rates, higher contrast medium concentration, and higher trigger levels may decrease the number of nondiagnostic studies in this population. MDCT may be a worthwhile investigation in the majority of pregnant patients with suspected pulmonary embolism.
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Value of monoenergetic low-kV dual energy CT datasets for improved image quality of CT pulmonary angiography. Eur J Radiol 2014; 83:322-8. [DOI: 10.1016/j.ejrad.2013.11.005] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 11/02/2013] [Accepted: 11/07/2013] [Indexed: 11/20/2022]
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Kilic K, Erbas G, Ucar M, Akkan K, Tokgoz N, Arac M, Isik S. Determination of lowest possible contrast volume in computed tomography pulmonary angiography by using pulmonary transit time. Jpn J Radiol 2014; 32:90-7. [DOI: 10.1007/s11604-013-0274-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 12/15/2013] [Indexed: 01/28/2023]
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KUDLIČKA J, MLČEK M, HÁLA P, LACKO S, JANÁK D, HRACHOVINA M, MALÍK J, BĚLOHLÁVEK J, NEUŽIL P, KITTNAR O. Pig Model of Pulmonary Embolism: Where Is the Hemodynamic Break Point? Physiol Res 2013; 62:S173-9. [DOI: 10.33549/physiolres.932673] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Early recognition of collapsing hemodynamics in pulmonary embolism is necessary to avoid cardiac arrest using aggressive medical therapy or mechanical cardiac support. The aim of the study was to identify the maximal acute hemodynamic compensatory steady state. Overall, 40 dynamic obstructions of pulmonary artery were performed and hemodynamic data were collected. Occlusion of only left or right pulmonary artery did not lead to the hemodynamic collapse. When gradually obstructing the bifurcation, the right ventricle end-diastolic area expanded proportionally to pulmonary artery mean pressure from 11.6 (10.1, 14.1) to 17.8 (16.1, 18.8) cm2 (p<0.0001) and pulmonary artery mean pressure increased from 22 (20, 24) to 44 (41, 47) mmHg (p<0.0001) at the point of maximal hemodynamic compensatory steady state. Similarly, mean arterial pressure decreased from 96 (87, 101) to 60 (53, 78) mmHg (p<0.0001), central venous pressure increased from 4 (4, 5) to 7 (6, 8) mmHg (p<0.0001), heart rate increased from 92 (88, 97) to 147 (122, 165) /min (p<0.0001), continuous cardiac output dropped from 5.2 (4.7, 5.8) to 4.3 (3.7, 5.0) l/min (p=0.0023), modified shock index increased from 0.99 (0.81, 1.10) to 2.31 (1.99, 2.72), p<0.0001. In conclusion, instead of continuous cardiac output all of the analyzed parameters can sensitively determine the individual maximal compensatory response to obstructive shock. We assume their monitoring can be used to predict the critical phase of the hemodynamic status in routine practice.
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Affiliation(s)
- J. KUDLIČKA
- Third Department of Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital, Prague, Czech Republic
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80-kV pulmonary CT angiography with 40 mL of iodinated contrast material in lean patients: comparison of vascular enhancement with iodixanol (320 mg I/mL)and iomeprol (400 mg I/mL). AJR Am J Roentgenol 2013; 199:1220-5. [PMID: 23169711 DOI: 10.2214/ajr.11.8122] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE The purpose of this article is to compare the vascular enhancement obtained with a low-kilovoltage pulmonary CT angiography (CTA) protocol in lean patients, using 40 mL of a moderate-concentration isoosmolar (iodixanol, 320 mg I/mL) and a high-concentration low-osmolar (iomeprol, 400 mg I/mL) iodinated contrast medium injected at the same iodine delivery rate. SUBJECTS AND METHODS Forty-two lean patients (31 men and 11 women; body mass index, ≤ 23 kg/m(2)) with suspected pulmonary embolism and non-small cell lung carcinoma underwent pulmonary CTA with a 64-MDCT scanner using a tube voltage of 80 kV. Twenty-three patients (54.8%) received 40 mL of iodixanol (320 mg I/mL) injected at a rate of 5 mL/s, and the remaining 19 patients (45.2%) were administered an equal volume of iomeprol (400 mg I/mL) at a flow rate of 4 mL/s. Intraarterial density was measured in the common pulmonary artery trunk, the main right and left pulmonary arteries, lobar arteries, and at the segmental level, for a total of 15 regions of interest per patient. Intravascular enhancement homogeneity from central to subsegmental level was also assessed visually using a semiquantitative score (1 = poor, 2 = good, and 3 = excellent). RESULTS The overall vascular density of pulmonary arteries down to the segmental level was significantly higher with iodixanol (320 mg I/mL) than with iomeprol (400 mg I/mL) (p = 0.036). Enhancement homogeneity was good with both contrast agents, with no statistically significant difference between them (p = 0.8966). CONCLUSION In 80-kV pulmonary CTA of lean patients, higher intravascular enhancement can be achieved with 40 mL of iodixanol (320 mg I/mL) than with the same volume of iomeprol (400 mg I/mL), with good vessel conspicuity down to the subsegmental level.
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Rodrigues J, Mathias H, Negus I, Manghat N, Hamilton M. Intravenous contrast medium administration at 128 multidetector row CT pulmonary angiography: Bolus tracking versus test bolus and the implications for diagnostic quality and effective dose. Clin Radiol 2012; 67:1053-60. [DOI: 10.1016/j.crad.2012.02.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 02/08/2012] [Accepted: 02/17/2012] [Indexed: 11/27/2022]
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Age-related incidence of pulmonary embolism and additional pathologic findings detected by computed tomography pulmonary angiography. Eur J Radiol 2012; 81:1913-6. [DOI: 10.1016/j.ejrad.2011.04.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 04/06/2011] [Indexed: 11/21/2022]
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CT Imaging of Pulmonary Embolism: Current Status. CURRENT CARDIOVASCULAR IMAGING REPORTS 2011. [DOI: 10.1007/s12410-011-9112-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Accuracy and reproducibility of blood clot burden quantification with pulmonary CT angiography. AJR Am J Roentgenol 2011; 196:516-23. [PMID: 21343492 DOI: 10.2214/ajr.10.4603] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE The purpose of our study was to assess the accuracy and reproducibility of clot burden quantification with pulmonary CT angiography (CTA). MATERIALS AND METHODS A semiautomated program was developed for segmentation and volumetric quantification of pulmonary embolus with pulmonary CTA. The accuracy of this measurement method was assessed using two pulmonary embolus phantoms. Reproducibility of the measurement method was assessed using clinical pulmonary CTA in 30 patients (16 women, 14 men; mean age, 62 years) with pulmonary embolism (PE). Two observers segmented and measured the volume of blood clot from pulmonary CTA images twice at two separate sessions. Accuracy was evaluated by the relative volume measurement error. Intra- and interobserver reliability were evaluated using intraclass correlation coefficient (ICC); agreement between measurements within and between the two observers was assessed using Bland-Altman analysis. RESULTS Mean relative measurement error from the two phantoms was less than 1% for both observers. A total of 60 emboli were measured from the 30 patients. The intraobserver ICC was 0.990 for observer 1 and 0.999 for observer 2; interobserver ICC was 0.994 for session 1 and 0.989 for session 2. ICC for all four clot measurements was 0.988. Mean volume measurement difference for intraobserver agreement was 0.9% for observer 1 and 0.3% for observer 2, and interobserver agreement was -5.1% for session 1 and -5.8% for session 2. CONCLUSION Blood clot burden can be quantified with a high degree of accuracy and reproducibility from pulmonary CTA images using a semiautomated segmentation method.
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