The diagnostic criteria for chronic pulmonary embolism include complete occlusion of a vessel that is permanently smaller than pulmonary arteries of the same order of branching [32, 33] (Fig. The most robust CT sign is right ventricular dilation (in which the greatest right ventricle short-axis measurement is wider than the maximum left ventricle short-axis measurement) [38] (Fig. What is a CT pulmonary angiogram? Purpose: To retrospectively review imaging characteristics of indeterminate computed tomographic (CT) pulmonary angiograms for pulmonary embolism (PE) and patient outcome. Contrast-enhanced helical CT of the veins of the lower extremities is performed using the same contrast bolus as used for chest CT. CT Pulmonary Angiography: A Comparative Analysis of the Utilization Patterns in Emergency Department and Hospitalized Patients Between 1998 and 2003. In 1990, the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study results were published [3]. 14, European Respiratory Journal, Vol. Acta Radiol October 8, 2013 One could argue that when the triggering threshold for bolus tracking is increased, CT would start later on the rise of the enhancement curve. • Wittram C, Maher MM, Halpern E, Shepard JO. It has been suggested that the early detection of acute right ventricular failure allows the implementation of the most appropriate therapeutic strategy [37]. Localized increase in vascular resistance can result from lung consolidation or atelectasis [27]. In practice, if a diagnosis of pulmonary embolism cannot be confidently confirmed or refuted and the study is indeterminate, it is recommended that the radiologist decide at which anatomic level the study is indeterminate; for example, if the radiologist can clear the vessels to the level of the segmental arteries, and the subsegmental arteries are indeterminate, the clinician might not require further imaging in cases with a low clinical pretest probability for pulmonary embolism. What is CTPA CT pulmonary angiography (CTPA) is a medical diagnostic test that employs computed tomography to obtain an image of the pulmonary arteries. Modern MDCT scanners are able to deliver images of sufficient resolution within a short time period, such that CTPA has now supplanted p Wijesuriya S(1), Chandratreya L(1), Medford AR(2). Computed tomography (CT) pulmonary angiography is widely used in patients with suspected pulmonary hypertension (PH). Interlobular reticulations, bronchiectasis (black arrowhead) and lung architectural distortion are present. Pulmonary CT Angiography as First-Line Imaging for PE: Image Quality and Radiation Dose Considerations John Mayo , Yogesh Thakur American Journal of Roentgenology . 12, JMV-Journal de Médecine Vasculaire, Vol. Therefore, we routinely performed contrast-enhanced CT for patients with COVID-19 with severe clinical features to evaluate the lung parenchyma as well as to evaluate other complications that may result in respiratory distress. The pulmonary vasculature may be evaluated with various invasive and noninvasive methods. The number of imaging studies for venous thromboembolism during pregnancy has increased dramatically. The pulmonary vasculature may be evaluated with various invasive and noninvasive methods. Pulmonary Thromboembolism in COVID-19: Venous Thromboembolism or Arterial Thrombosis? 22, No. Chest CT plays an important role in optimizing the treatment of patients with coronavirus disease 2019 (COVID-19) while also eliminating alternate diagnoses or added pathologic conditions, particularly for acute pulmonary embolism (1). The potential of the noninvasive technique, CT pulmonary angiography (CTPA), has now been realized at most institutions; it has become the test of choice and thus the de facto standard of care [4]. AJR 2011; 197:1058-1063. Prologo JD, Gilkeson RC, Diaz M, Asaad J.Department of Radiology, University Hospitals of Cleveland, 11100 Euclid Ave., Cleveland, OH 44106. 18, No. Pulmonary CT Angiography as First-Line Imaging for PE: Image Quality and Radiation Dose Considerations, Original Research. CT pulmonary angiography. The purpose of this article is to describe the techniques used to improve the quality of CT pulmonary angiography and to illustrate the diagnostic criteria of acute and chronic pulmonary emboli. 2004 Oct;183(4):1093-6 For more than 25 years, the direct signs of pulmonary embolism have been available to the radiologist on CT, and this noninvasive technique has produced a paradigm shift that has raised the standard of care for patients with this disease. 50, No. 1, The British Journal of Radiology, Vol. Involvement of the lung volume was estimated to be between 25% and 50%. 1, 15 December 2020 | Radiology, Vol. Pulmonary embolism is a common condition with considerable morbidity and mortality. CT angiography for pulmonary embolism detection: the effect of breathing on pulmonary artery enhancement using a 64-row detector system. Streak artifact that obscures pulmonary vessels because of metallic implants can make a study indeterminate, a repeat CT will not improve this problem, and additional imaging with V/Q scintigraphy or pulmonary angiography may be necessary. The fetal radiation dose from CT pulmonary angiography is substantially less than that from ventilation perfusion scintigraphy in all trimesters and even if half-dose perfusion-only scintigraphy is used [8-9]. The computed tomography pulmonary angiogram ( CTPA / CTPE) is a commonly performed diagnostic examination to exclude pulmonary emboli. 7, 23 October 2020 | RadioGraphics, Vol. Iodinated contrast medium is administered as a … In this manner, any case with adequate enhancement and no or minimal motion can be confidently interpreted. An angiography, sometimes called an arteriography, is a test doctors use to see your arteries. 2020 Sep;296(3):E189-E191. 2, Clinical Medicine (Russian Journal), Vol. 92, No. However, in cases with poor function of the right side of the heart, the enhancement threshold might never be reached; this leaves the technologist uncertain as to when to start image acquisition. 4, Advances in Difference Equations, Vol. 2020, No. Each radiology department will have a slightly different method for achieving the same outcome, i.e. Streak artifact from high-density contrast material in the superior vena cava can obscure adjacent pulmonary arteries. The injection duration has an important influence in optimizing contrast delivery in CT. Injection of contrast material can be considered in two components: first pass and recirculation. 2A, 2B). were instructed to have five respiratory cycles of hyperventilation followed by a command of full inspiration 2 seconds before initial images were obtained [24]. 6, The International Journal of Cardiovascular Imaging, Journal of Molecular Histology, Vol. 11, Journal of Cardiothoracic and Vascular Anesthesia, Baylor University Medical Center Proceedings, Vol. COVID-19= coronavirus disease 2019, RT-PCR = reverse-transcription polymerase chain reaction. 2A, 2B) because image acquisition is performed at the end of the injection. 6, Indian Journal of Medical Specialities, Vol. P < .05 was indicative of a significant difference. 11, Annals of Internal Medicine, Vol. The three major causes of mosaic lung attenuation are airways disease, chronic pulmonary embolism (in which the abnormal region is more radiolucent), and interstitial lung disease (in which the abnormal lung is more opaque). 45, No. 4, No. used single-detector CT whereas Wittram and Yoo used MDCT. Images of the iliac, femoral, and popliteal veins are obtained 3 minutes after the onset of the initial contrast injection [13]. Both acute and chronic pulmonary emboli are identified as intraluminal filling defects that show a sharp interface with IV contrast material. Acute pulmonary embolism and COVID-19 pneumonia: a random association? At the moment, the breath-hold required for 16-MDCT is approximately 10 seconds, and for 64-MDCT, less than 3 seconds. The main objective of our study was to evaluate pulmonary embolus in association with COVID-19 infection by using pulmonary CT angiography. It is a preferred choice of imaging in the diagnosis of PE due to its minimally invasive nature for the patient, whose only requirement for the scan is an intravenous line. 173, No. CT scans were obtained 10 days after the onset of coronavirus disease 2019 symptoms on the day the patient was transferred to the intensive care unit. Computed Tomography (CT) is the mainstay of diagnostic imaging evaluation of thoracic disorders. This large multicenter trial compared ventilation-perfusion (V/Q) scintigraphy with pulmonary angiography and established the diagnostic characteristics of pulmonary embolism on V/Q scintigraphy. Catheter pulmonary angiography is also underutilized. 1,2 Since the 1990s, CT pulmonary angiography (CTPA) has become the method of choice for imaging in suspected PE. Images are viewed on a PACS monitor using IMPAX version 4.1 (AGFA) because there is improved accuracy in viewing chest CT cases on a workstation compared with hard-copy film [9, 10]. Hounsfield unit values of acute and chronic pulmonary emboli. • Describe the techniques used to improve the quality of MD-CTPA • Illustrate the diagnostic criteria of chronic and acute pulmonary emboli • Illustrate common artifacts and pitfalls in imaging and diagnosis 3. 3, Saudi Critical Care Journal, Vol. 6, Academic Emergency Medicine, Vol. Author contributions: Guarantors of integrity of entire study, F.G., J.B., E.D. CT Diagnosis of Acute Mesenteric Ischemia from Various Causes. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. This retrospective study was approved by our institutional review board. 130, Diagnostic and Interventional Imaging, Vol. Enter your email address below and we will send you the reset instructions. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first‐line imaging … (6)Department of Radiology, University of Chicago, Chicago, IL, United States. 64, No. 30, No. They are best seen on lung window settings that show composite images of vessels [11]. had access to the study data. Non-invasive imaging techniques have recently been used to replace arteriography. OBJECTIVE. ; clinical studies, F.G., J.B.; statistical analysis, P.C. 6, International Journal of Infectious Diseases, Vol. See www.arrs.org for more information. Comparing patients with this artifact with age- and sex-matched controls, Wittram and Yoo [25] showed that the artifact results from an increase in flow of unopacified blood from the inferior vena cava. 40, No. [17], we need attenuation in the artery of at least one more SD; the final figure therefore equals 93 H. The mean attenuation and SD values for chronic pulmonary embolism are 87 and 31 H, respectively. The frequency of examinations devoid of motion artifacts is significantly higher for MDCT, which has a shorter breath-hold than single-detector CT [14, 15]. CT pulmonary angiography: Has replaced conventional pulmonary angiography as the reference standard for pulmonary embolism diagnosis because of its ease of performing and high sensitivity and specificity. Question Given increasing concerns of imaging overuse for pulmonary embolism, has the use of computed tomographic pulmonary angiography (CTPA) decreased over time?. ; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; agrees to ensure any questions related to the work are appropriately resolved, all authors; literature research, F.G., J.B., E.D. Patients with pulmonary embolus were more likely to require care in the critical care unit and to require mechanical ventilation compared with those without pulmonary embolus. The hyperventilation before inspiration and the breath-hold is likely the exacerbating factor of this artifact. In cases of discordance, a simultaneous reading to reach consensus was achieved. A recent study that evaluated the causes of indeterminate CTPA findings found an indeterminate rate of 6.6% [8]. ; and manuscript editing, all authors. CT scan settings were as follows: 120 kVp, collimation of 80 × 0.625 mm, rotation time of 0.28 second, average tube current of 300 mA, pitch of 0.992, and volume CT dose index of 4.28 mGy. Nonuniform arterial perfusion due to acute pulmonary embolism can uncommonly manifest as a mosaic pattern of attenuation on CT. Additional indirect signs seen in chronic pulmonary embolism include poststenotic dilatation, tortuous vessels, enlargement of the main pulmonary artery, and enlargement of the bronchial arteries [36]. Further study is required to assess the possible benefits of these maneuvers. At multivariable analysis, requirement for mechanical ventilation (odds ratio = 3.8 [95% confidence interval: 1.02, 15], P = .049) remained associated with acute pulmonary embolus (Table E3, Appendix E1 [online]). Therefore, the use of contrast-enhanced CT rather than routine unenhanced CT may be considered for these patients. 52, No. Both studies used the same injection rate, but Gosselin et al. 27, No. A 1990 study showed that pulmonary angiography had a sensitivity of only 87% for PE. A, B, Axial CT images (lung windows) show peripheral ground-glass opacities (arrow in A) associated with areas of consolidation in dependent portions of the lung (white arrowhead). 0, 8 December 2020 | Radiology, Vol. 134, No. Of these 280 patients, 129 (46%) underwent CT a mean of 9 days ± 5 (standard deviation) after symptom onset. 29, No. Consecutive patients with suspected PH undergoing routine CT pulmonary angiography and right … 101, No. 6, American Journal of Neuroradiology, Vol. 3); second, a central arterial filling defect surrounded by IV contrast material [31] (Fig. Nevertheless, our results suggest that patients with severe clinical features of COVID-19 may have associated acute pulmonary embolus. The sensitivity of V/Q scintigraphy was found to be 98%, with a specificity of 10% [3]. The most common cause was motion artifacts in 74% of the cases; other reasons included poor enhancement (40%), patient habitus (7%), parenchymal disease (12%), and streak artifacts (7%) [8]. It is regarded as a highly
sensitive and specific test for pulmonary embolism.
3. In this paper we describe an efficient tool based on natural language processing for classifying the detail state of pulmonary embolism (PE) recorded in CT pulmonary angiography reports. CTPA was introduced in the 1990s as an alternative to ventilation/perfusion scanning, which relies on radionuclide imaging of the blood vessels of the lung. Empiric scanning delay also has the advantage of reducing operator error and motion artifacts by removing the added complexity of when to start the study based on a threshold value. Our routine protocol for patients with severe clinical features of COVID-19 infection was multidetector pulmonary CT angiography using a 256-slice multidetector CT scanner (Revolution; GE Healthcare, Milwaukee, Wis) after intravenous injection of 60 mL iodinated contrast material (Iomeprol, 400 mg of iodine per milliliter; Bracco Imaging, Milan, Italy) at a flow rate of 4 mL/sec, triggered on the … Using an empiric scanning delay on 16- and 64-MDCT scanners, one aims to be midscan at the peak of pulmonary artery enhancement; therefore, the start of the scanning is calculated to equal the injection time minus half the scanning time. 56, No. The bronchi are normal, as is the pulmonary parenchyma. Ankle Ligaments on MRI: Appearance of Normal and Injured Ligaments, Original Research. A region-of-interest measurement may be helpful in this decision if the attenuation is greater than 78 H, which is the upper value of acute pulmonary emboli [16]. Pulmonary CT Angiography Protocol Adapted to the Hemodynamic Effects of Pregnancy. To analyze pulmonary embolism (PE) on chest computed tomography pulmonary angiography (CTPA) in hospitalized patients affected by SARS-CoV-2, according to the severity of lung disease based both on temporal CT features changes and on CT-severity lung involvement (CT-severity score), along with the support of clinical and laboratory findings. It is a unique tool that can visualize disease in the smallest pulmonary vessels, diagnose clinically important coexisting disease, detect the source of thromboembolism, evaluate the deep venous system, and assess the functional sequelae of the embolic event. Studies by Schluger et al 13 and Sostman et al 14 found that, in the majority of cases, physicians chose not to perform pulmonary angiography if the V/Q scan was nondiagnostic. C, D, Coronal CT reformations (mediastinum windows) show bilateral lobar and segmental pulmonary embolism (arrows). Electronic medical records were reviewed for follow-up imaging (repeat CT pulmonary angiography, conventional pulmonary angiography, ventilation-perfusion scintigraphy, or lower-extremity ultrasonography [US]), use of anticoagulation, placement of inferior vena cava (IVC) filters, clinical outcomes, and comments regarding indeterminate reading of CT angiograms. [17], it is possible to calculate the minimum amount of IV attenuation required to perceive pulmonary emboli on CT. Meaney et al. These permissions are granted for the duration of the COVID-19 pandemic or until permissions are revoked in writing. Historically, catheter-directed pulmonary angiography has been used most commonly for the diagnosis of suspected pulmonary embolism (PE). Also, the decision of the reviewer to interpret a study as adequate or indeterminate will be affected by the interplay of factors that include the size of the suspected embolism, the anatomic level of the vessel being evaluated, and the amount of image noise. A rapid change in position of vessels on contiguous images also confirms motion artifact. Using contrast injected into the blood vessels, images are created to look for blockages, aneurysms (dilations of walls), dissections (tearing of walls), and stenosis (narrowing of vessel). Centre Hospitalier Universitaire de Besançon, Boulevard Fleming, 25030 Besançon, France (F.G., J.B., P.C., S.A., E.D. Pulmonary angiography 1. 2, No. Conventional computed tomographic (CT) scanning is, however, at a disadvantage because of its inability to obtain multiplanar images. 12, International Journal of Antimicrobial Agents, Vol. Medical Sciences, Vol. Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used to visualize arterial and venous vessels throughout the body. 11, Journal of Medical Virology, Vol. The diagnostic criteria for acute pulmonary embolism include, first, complete arterial occlusion with failure to opacify the entire lumen; the artery may be enlarged in comparison with pulmonary arteries of the same order of branching [31-33] (Fig. 9, Clinical and Applied Thrombosis/Hemostasis, Vol. By Carole A. Ridge et al. 40, No. Indirect CT venography will not be dealt with in detail in this article. 67, No. 20, No. In contrast, its role in CTEPH is less well defined. [2] were among the first to describe pulmonary embolism on contrast-enhanced CT. Suboptimal enhancement of CT pulmonary angiograms leads to non diagnostic studies and therefore unnecessary exposure to contrast and radiation. Although our experience is anecdotal, this is an uncommon artifact with empiric timing delay; it is likely due to the wider temporal window of contrast injection that occurs with empiric timing delay compared with other techniques (Fig. A review of the literature shows that the transient interruption of contrast artifact was seen in 3% of the study population in that study [25], whereas in the study by Gosselin et al. In my experience, this finding is more often seen on angiography than on CT; this discrepancy is thought to be related to the larger temporal window of IV contrast material for CT as compared with angiography. Classification of a pulmonary embolism may be based upon: 1. the presence or absence of hemodynamic compromise 2. temporal pattern of occurrence 3. the presence or absence of symptoms 4. the vessel which is occluded 0, No. 11, Journal of Cardiovascular Computed Tomography, Journal Européen des Urgences et de Réanimation, Vol. 12, International Journal of Legal Medicine, Vol. 14, No. Radiology 2005: 235; 1050-1054. No author has any conflict of interest to declare in relation to this study. Further imaging may be necessary, either repeating CTPA with an increased delay or pulmonary angiography. It followed the ethical guidelines of the Declaration of Helsinki. CTA (CTPA – CT pulmonary angiography) has been the technique of choice for detection of pulmonary embolism for at least the last decade . Acute Pulmonary Embolism in Patients with COVID-19 at CT Angiography and Relationship to d-Dimer Levels Radiology . 6, Journal of Medical Imaging and Radiation Oncology, Vol. 4, Journal of Crohn's and Colitis, Vol. 12. Current guidelines (1,5,6) recommend performing unenhanced chest CT to assess the COVID-19 CT pattern and its extension. 98, No. Diagnostic quality of CT pulmonary angiography in pulmonary thromboembolism: A comparison of three different kV values. Because the indirect signs have a differential diagnosis, they are helpful only as indicators of the sites of the direct radiologic signs of pulmonary embolism. International Journal of Infectious Diseases, Vol. No bony abnormality is identified. The indeterminate CT pulmonary angiogram: imaging characteristics and patient clinical outcome. AJR Am J Roentgenol. Overdiagnosis of Pulmonary Embolism by Pulmonary CT Angiography, Review. doi: 10.1148/radiol.2020201561. Pulmonary embolus was diagnosed a mean of 12 days from symptom onset. The pleural spaces are clear. Less complication than conventional (elevated pulmonary ... against which all other modalities have beenmeasured. Endorsed by the Society of Thoracic Radiology, the American College of Radiology, and RSNA, The Role of Chest Imaging in Patient Management during the COVID-19 Pandemic: A Multinational Consensus Statement from the Fleischner Society, https://doi.org/10.1148/radiol.2020201544, Open in Image
Pulmonary embolism (PE) is a common condition with high mortality and morbidity. Several techniques are available for contrast delivery on CT studies. As for reviewing vessels surrounded by consolidation, as with all radiology interpretation, it is important to be systematic and review one vessel at a time and ignore the consolidation or any other pathology that might distract the attention of the reviewer. For the more than 25 years that the direct signs of pulmonary embolism have been available to the radiologist on CT, this noninvasive technique has produced a paradigm shift that has raised the standard of care for patients with this disease. Chronic pulmonary emboli and radiologic mimics on CT pulmonary angiography: a diagnostic challenge. Supplement_3, QJM: An International Journal of Medicine, American Journal of Therapeutics, Vol. 98, No. 93, No. To detect abnormalities with low differences in CT contrast, and to improve pulmonary embolism conspicuity, it is necessary to adjust the display window widths and levels [17-19]. In all CT scanners various types of filter are available to vary the degree of definition of the image profiles (filters for bone, soft tissue, etc.). In addition to standard CT studies of the lungs for infection and cancer, high-resolution CT studies of the lungs for diagnosis and evaluation of treatment effectiveness for diffuse lung disease (a group of disorders causing progressive scarring of lung tissue) are now routine. ). Over the past two decades, however, catheter angiography has become almost entirely supplanted by CT angiography (CTA), which is now the … CTPA was introduced in the 1990s as an alternative to ventilation/perfusion scanning, which relies on radionuclide imaging of the blood vessels of the lung. We acknowledge the preliminary nature of these findings, including its retrospective nature and limited sample size. Of 2003 patients diagnosed with COVID-19, 280 were hospitalized during the study period. [24], it was present in 37% of the study group. This enhancement advantage is most optimally used with the empiric delay technique, whereas bolus tracking starts the CT scan earlier on the rise of the enhancement curve and results in worse pulmonary artery enhancement. 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