1, Clinical Pulmonary Medicine, Vol. Respiratory motion artifacts are the most common cause of indeterminate CT pulmonary angiography and can cause misdiagnosis of pulmonary embolism. This artifact can be recognized by its nonanatomic nature and is easily distinguished from pulmonary embolism. 80, No. Brink et al (,29) suggested a window width equal to the measured mean attenuation of the enhanced main pulmonary artery plus two standard deviations and a window level equal to one-half of this value (,,,,Fig 25). These findings indicate the true nature of the patient’s condition.Download as PowerPointOpen in Image (a) On a CT scan, a pulmonary artery catheter causes adjacent beam-hardening artifacts within the main and right pulmonary arteries that mimic pulmonary embolism (arrows). CT scan shows an eccentrically located thrombus that forms obtuse angles with the vessel wall (arrows). (b) CT scan (lung window) demonstrates the accompanying findings of diffuse peribronchovascular thickening, ground-glass attenuation, smooth interlobular septal thickening (arrows), and bilateral pleural effusions. 5, No. 65, No. Chronic pulmonary embolism can manifest as complete occlusive disease in vessels that are smaller than adjacent patent vessels. Figure 17. 27, No. )Download as PowerPointOpen in Image ), Figure 2. This partial filling defect surrounded by contrast material produces the polo mint sign (arrow). Pulmonary emboli have been identified on 1.5% of contrast-enhanced CT scans obtained for reasons other than evaluation for pulmonary embolism (, 21). 47, No. Viewer, Figure 1. Figure 15. Figures 1-3 demonstrate the timing of changes that occur when a new technology replaces an old one; in this case, a downturn in the use of pulmonary angiography and ventilation-perfusion scintigraphy almost exactly coincides with a steep increase in CT pulmonary angiography usage. (a) CT scan shows a flow artifact caused by a localized increase in vascular resistance (arrow), a finding that can mimic acute pulmonary embolism. 4, 13 March 2015 | Hospital Practice, Vol. Because the signs and symptoms are inconsistent, the diagnosis is often missed. Another acute pulmonary embolus affects the left main pulmonary artery (arrowhead). (b) Contiguous CT scan obtained inferior to a demonstrates normal lung adjacent to the left upper lobe pulmonary artery. Figure 35c. 5, 1 January 2009 | RadioGraphics, Vol. 35, No. Acute occlusive pulmonary embolism in a 32-year-old woman who presented with chest pain. 199, No. Figure 40. 2, Seminars in Ultrasound, CT and MRI, Vol. Respiratory motion artifact in a 61-year-old man with dyspnea. Small pulmonary emboli could be obscured by a large amount of image noise. 12, No. Multiplanar reformatted images through the longitudinal axis of a vessel are sometimes used to overcome various difficulties encountered with axial sections of obliquely or axially oriented arteries (,13). Acute central pulmonary embolism in an asymptomatic 87-year-old woman. (b) CT scan obtained with the standard algorithm does not demonstrate this artifact. 30, No. 2, Revista Argentina de Radiología, Vol. (b) CT scan obtained with the standard algorithm does not demonstrate this artifact. 8, American Journal of Roentgenology, Vol. 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 30, No. Left-sided heart failure in a 56-year-old woman with dyspnea. Mucus plugs in an 83-year-old woman with dyspnea. Note the dilated collateral bronchial artery (arrowhead).Download as PowerPointOpen in Image Intravascular tumor emboli can manifest as large, acute pulmonary emboli that produce acute pulmonary hypertension by occluding main, lobar, or segmental pulmonary arteries. Viewer. CT CHEST, ABDOMEN AND PELVIS WITHOUT + CTA CHEST W IV AND CTA ABDOMEN W IV (Please order both exams) 71250, 74150, 72192 71275 and 74175 Pulmonary arteries Pulmonary embolism Pulmonary hypertension Hemoptysis None Yes CTA CHEST W IV 71275 Lower extremities Peripheral Artery Disease None Yes CTA PELVIS W/RUNOFFS 75635 Viewer. The appropriate window width and level settings are important for identifying small emboli, webs, or flaps. Arrows indicate collateral bronchial arteries.Download as PowerPointOpen in Image (a) Unenhanced CT scan demonstrates subtle regions of hyperattenuation (arrow). CT scan shows a pulmonary embolus within the posterobasal segment of the right lower lobe artery (arrow). Chest wall abnormalities such as rib fractures and metastatic deposits may also mimic pulmonary embolism. Graph illustrates that the number of ventilation-perfusion scans performed per inpatient with suspected thromboembolic disease decreased significantly between 1992 and 2001 (P = .0003). Figure 14. (a) CT scan shows poor enhancement of the interlobar and middle lobe pulmonary arteries due to flow-related artifact. Adjacent beam-hardening artifacts are also seen. Acute occlusive pulmonary embolism in a 32-year-old woman who presented with chest pain. 48, No. Factors that cause misdiagnosis of pulmonary embolism may be patient related, technical, anatomic, or pathologic. (a) On a CT scan, a pulmonary artery catheter causes adjacent beam-hardening artifacts within the main and right pulmonary arteries that mimic pulmonary embolism (arrows). Figure 32. The window width is equal to the mean attenuation of the main pulmonary artery plus two standard deviations, and the window level equals one-half of this value (,29). Contrasted CT-angiography of the chest, often called a "PE protocol CT," has dramatically improved the diagnosis of pulmonary embolism. Beam-hardening artifact in a 63-year-old man with respiratory failure. Pulmonary embolism CT technique does not use gating. 6, No. 2. Viewer. (d) Subsequent angiogram demonstrates slight distortion of the posterobasal segment of the left lower lobe pulmonary artery (arrow) but no evidence of pulmonary embolism. Viewer. Knowledge of hilar lymph node anatomy assists in differentiating lymph nodes from pulmonary embolism. The specifics will vary depending on CT hardware and software, radiologists' and referrers' preference, institutional protocols, patient factors (e.g. 6, IEEE Transactions on Biomedical Engineering, Vol. 4, Seminars in Roentgenology, Vol. (b) CT scan shows acute emboli that affect subsegmental arteries of the laterobasal segment (arrows). (a) On a 3.75-mm-thick CT scan, partial volume averaging of vessel and lung creates an artifact that mimics pulmonary embolism within the anterior segment of the left upper lobe pulmonary artery (arrow). The diagnostic criteria for chronic pulmonary embolism include (a) complete occlusion of a vessel that is smaller than adjacent patent vessels (,Fig 11); (b) a peripheral, crescent-shaped intraluminal defect that forms obtuse angles with the vessel wall (,Fig 12); (c) contrast material flowing through thickened, often smaller arteries due to recanalization (,Fig 13); (d) a web or flap within a contrast material–filled artery (,Fig 14); and (e) secondary signs, including extensive bronchial or other systemic collateral vessels (,Figs 11, ,12, ,14, ,15), an accompanying mosaic perfusion pattern (,Fig 16), or calcification within eccentric vessel thickening (,Fig 17) (,15,,17). N Engl J Med 2019;381:2125-34. 5, 24 March 2017 | Current Radiology Reports, Vol. Acute pulmonary embolism in a 59-year-old man. 33, No. 5, American Journal of Roentgenology, Vol. Note also the fluid-filled, dilated esophagus. As CT scanners become faster, delaying initial image acquisition until approximately 5 seconds after inspiration should allow the transient interruption in contrast material to pass through the pulmonary circulation (,27). Localized increase in vascular resistance in a 65-year-old man with dyspnea. Figure 5b. This artifact can be recognized by its nonanatomic nature and is easily distinguished from pulmonary embolism.Download as PowerPointOpen in Image Note also the medium-sized left pleural effusion and atelectasis. However, further imaging may be necessary to exclude thrombus hidden in poorly enhanced vessels (,,,Fig 24). 24, No. CT scan shows tumor emboli that manifest as vascular dilatation and beading of subsegmental arteries of the posterobasal segment of the right pulmonary artery (arrow). With a 1.25-mm detector width, normal or enlarged lymphatic tissue can be more easily distinguished from acute or chronic pulmonary embolism because lymphatic tissue is extramural and the normal smooth contour of the contrast material–filled vessel is preserved (,,,,,Fig 30). (b) CT scan (lung window) demonstrates the accompanying findings of diffuse peribronchovascular thickening, ground-glass attenuation, smooth interlobular septal thickening (arrows), and bilateral pleural effusions. Stair step artifact consists of low-attenuation lines seen traversing a vessel on coronal and sagittal reformatted images (,Fig 29) and is accentuated by cardiac and respiratory motion. 50, No. Figure 25a. Noninspiratory imaging important to avoid transient attenuation artifact, due to contrast dilution from mixing of IVC blood if patient Valsalvas. 80, 1 October 2015 | Radiologia Brasileira, Vol. The diagnostic criteria for acute pulmonary embolism include the following: Arterial occlusion with failure to enhance the entire lumen due to a large filling defect; the artery may be enlarged compared with adjacent patent vessels (,Fig 4). 58, No. 38, No. (a) CT scan shows a flow artifact caused by a localized increase in vascular resistance (arrow), a finding that can mimic acute pulmonary embolism. ), Figure 4. (,Fig 1 modified and Figs 1-3 reprinted, with permission, from reference ,12. 6, American Journal of Roentgenology, Vol. 30, No. 256 (1): 32-61. (a) On a CT scan, a pulmonary artery catheter causes adjacent beam-hardening artifacts within the main and right pulmonary arteries that mimic pulmonary embolism (arrows). 2, Current Problems in Diagnostic Radiology, Vol. Figure 9. 21, No. Figure 31. Further imaging may be necessary, consisting of either repeat CT pulmonary angiography with an increased delay or pulmonary angiography. Figure 30d. An apparent filling defect that mimics acute pulmonary embolism may be identified. (e) More oblique angiogram of the left pulmonary artery also demonstrates no evidence of pulmonary embolism (arrow). Viewer. Chronic pulmonary embolism in a 56-year-old man with dyspnea. (d) Subsequent angiogram demonstrates slight distortion of the posterobasal segment of the left lower lobe pulmonary artery (arrow) but no evidence of pulmonary embolism. Acute pulmonary embolism in a 59-year-old man. (b) CT scan obtained with the standard algorithm does not demonstrate this artifact. 12, Clinical Pulmonary Medicine, Vol. (a) CT scan shows peribronchovascular interstitial thickening caused by perivascular edema (arrow), a finding that can mimic chronic pulmonary embolism. 196, No. Early detection of acute right ventricular failure allows implementation of the most appropriate therapeutic strategy. Viewer. Streak artifact in a 35-year-old woman with chest pain. No embolism was present.Download as PowerPointOpen in Image There are two principal approaches for performing a CTPA of high diagnostic quality: NB: This article is intended to outline some general principles of protocol design. Figure 16. Graph illustrates that the number of ventilation-perfusion scans performed per inpatient with suspected thromboembolic disease decreased significantly between 1992 and 2001 (P = .0003). Parenchymal density changes in acute pulmonary embolism: Can quantitative CT be a diagnostic tool? Figure 28b. The reason for indeterminacy is reported, along with the extent of normalcy. Small pulmonary emboli are noted in the left pulmonary artery. However, this increased detector width also decreases sensitivity for detection of pulmonary embolism (,25). Figure 6. Figure 28c. 4, Korean Journal of Radiology, Vol. Figure 30d. Viewer, Figure 2. Figure 26. Introduction: Use of CT in the investigation of pulmonary embolism in radiosensitive patients such as pregnant and young female patients entails the need for protocol optimization. 10, 11 March 2017 | Veterinary Radiology & Ultrasound, CT and MRI Vol! European Radiology, Vol dramatically improved the diagnosis of pulmonary embolism ( arrow ).Download as PowerPointOpen Image... Abnormalities are not well-defined filling defects (,,, Fig 1 modified and Figs reprinted! Via vein in upper limb failure is optimally monitored with echocardiography and pelvis ) a finding indicates! 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