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). 1, 8 August 2017 | Veterinary Radiology & Ultrasound, Vol. 3, 12 November 2017 | Iranian Journal of Radiology, Vol. 55, No. 13, No. Large tumor emboli, a rare cause of intravascular filling defects, result from direct invasion of the inferior vena cava or its major branches by hepatoma, renal cell carcinoma, or choriocarcinoma (,42). 6, American Journal of Roentgenology, Vol. Computed tomographic pulmonary angiography (CTPA) has become the standard of care for the evaluation of patients with suspected pulmonary embolism (PE) in most institutions. Adjacent beam-hardening artifacts are also seen.Download as PowerPointOpen in Image (b) CT scan (mediastinal window) demonstrates a low-attenuation abnormality caused by partial volume averaging of vessel and adjacent lung (arrow), a finding that can simulate pulmonary embolism.Download as PowerPointOpen in Image (e) More oblique angiogram of the left pulmonary artery also demonstrates no evidence of pulmonary embolism (arrow). (c) CT scan (window width = 700 HU, window level = 100 HU) demonstrates thrombus within the right interlobar artery and the medial segment of the middle lobe artery. The use of either clinical probability adjusted or age adjusted D-dimer interpretation has led to … When a rapid diagnosis of pulmonary embolism is essential for patients with chronic pulmonary hypertension possibly secondary to central embolism, particularly patients being considered for pulmonary thromboendarterectomy. The apparent pulmonary embolism is ill defined. CT scan shows an acute pulmonary embolus with ancillary findings of a peripheral wedge-shaped area of hyperattenuation in the lung (arrow), a finding that may represent an infarct, as well as a linear band (arrowhead).Download as PowerPointOpen in Image Supine Contrast IV: Up to 100 ml Omni 350. Note also the medium-sized left pleural effusion and atelectasis. 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). CT scan reveals a small, recanalized pulmonary artery with contrast material in the central lumen (arrow). (b) CT scan (window width = 552 HU, window level = 276 HU) shows acute pulmonary embolism within the medial segment of the middle lobe artery (arrow) that was missed on the image in a. Figure 15. The radiologist needs to determine the quality of a CT pulmonary angiographic study and whether pulmonary embolism is present. Figure 37. 12, Clinical Pulmonary Medicine, Vol. Graph illustrates that the number of ventilation-perfusion scans performed per inpatient with suspected thromboembolic disease decreased significantly between 1992 and 2001 (P = .0003). 244, No. These CT findings include (a) right ventricular dilatation (in which the right ventricular cavity is wider than the left ventricular cavity in the short axis) (,Fig 9) (,19), with or without contrast material reflux into the hepatic veins; (b) deviation of the interventricular septum toward the left ventricle (,Fig 9) (,19); or (c) a pulmonary embolism index greater than 60% (,20). 1104, Current Pulmonology Reports, Vol. (a) CT scan obtained with an edge-enhancing algorithm shows a lung algorithm artifact that mimics acute pulmonary embolism (arrows). 184, No. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. (d) Subsequent angiogram demonstrates slight distortion of the posterobasal segment of the left lower lobe pulmonary artery (arrow) but no evidence of pulmonary embolism. The Clinical Respiratory Journal, Vol. On occasion, intravascular thrombosis is identified in a pulmonary artery stump. Enter your email address below and we will send you the reset instructions. 7, Radiologic Clinics of North America, Vol. In 17 patients with central pulmonary embolism, the raw data were used to perform reconstructions with 1-mm, 2-mm, and 3-mm section thicknesses. (b) CT scan (window width = 552 HU, window level = 276 HU) shows acute pulmonary embolism within the medial segment of the middle lobe artery (arrow) that was missed on the image in a. 3, 10 January 2014 | Expert Review of Cardiovascular Therapy, Vol. 85, No. CT scan shows an acute pulmonary embolus with ancillary findings of a peripheral wedge-shaped area of hyperattenuation in the lung (arrow), a finding that may represent an infarct, as well as a linear band (arrowhead). 2, Singapore Medical Journal, Vol. For example, vessels may appear normal to the level of the segmental arteries; however, the presence of pulmonary embolism in subsegmental arteries may remain indeterminate depending on the quality of the study. The total cavopulmonary connection (TCPC), or Fontan procedure, diverts systemic venous blood directly into the pulmonary arteries and is the palliative surgery of choice for patients with a wide variety of congenital heart diseases with single-ventricle physiologic characteristics. 35, No. Figure 23. (c) Contiguous CT scan obtained immediately superior to a demonstrates a contrast material-filled pulmonary artery, a finding that confirms that the low attenuation seen in a was due to partial volume artifact. Figure 25 illustrates the effect of different window settings on detection of pulmonary embolism.Download as PowerPointOpen in Image 2, American Journal of Roentgenology, Vol. (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). (e) More oblique angiogram of the left pulmonary artery also demonstrates no evidence of pulmonary embolism (arrow). However, these radiologic features are not specific for pulmonary embolism. 30, No. If the address matches an existing account you will receive an email with instructions to reset your password. CT scan shows a flap (arrow) within a small right interlobar pulmonary artery. Peripheral wedge-shaped areas of hyperattenuation that may represent infarcts, along with linear bands, have been demonstrated to be statistically significant ancillary findings associated with acute pulmonary embolism (,Fig 8) (,18). Figure 27b. CT scan shows pulmonary arterial wall calcification (arrows), a secondary sign of chronic pulmonary embolism.Download as PowerPointOpen in Image Because the signs and symptoms are inconsistent, the diagnosis is often missed. Alternatively, repeat CT pulmonary angiography or conventional pulmonary angiography may be performed to evaluate for pulmonary embolism. (b) Confirmatory CT pulmonary angiogram demonstrates acute pulmonary embolism within the right main and left interlobar pulmonary arteries. Review, Chest multidetector computed tomography (MDCT) in patients with suspected acute pulmonary embolism: diagnostic yield and proportion of other clinically relevant findings, Accuracy and Reproducibility of Blood Clot Burden Quantification With Pulmonary CT Angiography, Amélioration de l’angioscanner thoracique dans le cadre d’une EPP, Use of CT Angiography in a Country with Low Pulmonary Embolism Prevalence: Correlation with Clinical Pretest Probability and D-dimer Values, Imaging in Acute Pulmonary Embolism With Special Clinical Scenarios, Pulmonary Embolism: Optimizing the Diagnostic Imaging Approach, Unsuspected Pulmonary Emboli in Oncology Patients Undergoing Routine Computed Tomography Imaging, Unsuspected Pulmonary Emboli in Pediatric Oncology Patients: Detection With MDCT, Non-Electrocardiogram-Gated Multidetector-Row Computed Tomography Findings of Cardiac Pathology in Oncologic Patients, CT Diagnosis of Chronic Pulmonary Thromboembolism1, Emergency Cardiac CT for Suspected Acute Coronary Syndrome: Qualitative and Quantitative Assessment of Coronary, Pulmonary, and Aortic Image Quality, Suspected pulmonary embolism and deep venous thrombosis: A comprehensive MDCT diagnosis in the acute clinical setting, Image Quality and Radiation Exposure at Pulmonary CT Angiography with 100- or 120-kVp Protocol: Prospective Randomized Study1, Discordance between CT and Angiography in the PIOPED II Study1, Preliminary Radiology Resident Interpretations Versus Final Attending Radiologist Interpretations and the Impact on Patient Care in a Community Hospital, Clinical Evaluation of a Computer-Aided Diagnosis (CAD) Prototype for the Detection of Pulmonary Embolism, Atypical Chest Pain: Coronary, Aortic, and Pulmonary Vasculature Enhancement at Biphasic Single-Injection 64-Section CT Angiography1, Computer Tomography for Venous Thromboembolic Disease, Imaging diagnosis of acute pulmonary embolism, Incidental Pulmonary Emboli in Oncology Patients: Prevalence, CT Evaluation, and Natural History1, Sarcome de l’artère pulmonaire dans le post-partum: aspects scanographiques, Pulmonary artery myxoma as a rare cause of dyspnea for a young female patient, Congenital and Acquired Pulmonary Artery Anomalies in the Adult: Radiologic Overview1, Computed Tomography and Pulmonary Embolus: A Review, Vascular Diseases of the Thorax: Evaluation with Multidetector CT, Opacification of the Inferior Vena Cava and Inspiration-Associated Artifacts. (a) CT scan shows a flow artifact caused by a localized increase in vascular resistance (arrow), a finding that can mimic acute pulmonary embolism. We use pulmonary embolism–specific settings with a window width and level of 700 and 100 HU, respectively (,,,,Fig 25c). (b) Contiguous CT scan obtained inferior to a demonstrates normal lung adjacent to the left upper lobe pulmonary artery. CT scan shows an eccentrically located thrombus that forms obtuse angles with the vessel wall (arrows). Viewer. A widely accepted formula for calculating the scan delay is, peak contrast enhancement (time-enhancement curve) + scanner's diagnostic scan delay, what constitutes as a diagnostic CTPA based on enhancement varies from site-to-site, changing the scan direction to caudocranial has been shown to better demonstrate the lower lobes whilst alleviating artefact from the contrast bolus in the SVC, use of high-pitch-scanning in non-obese patients can see a reduction in contrast use to as low as 12ml. The radiologist needs to determine the quality of a CT pulmonary angiographic study and whether pulmonary embolism is present. Arrows indicate collateral bronchial arteries. Further imaging may be necessary, consisting of either repeat CT pulmonary angiography with an increased delay or pulmonary angiography. Pulmonary embolism is a common and potentially fatal cardiovascular disorder that must be promptly diagnosed and treated. CT scans demonstrate normal hilar lymph nodes in both upper lobes (arrows in a), adjacent to the right and left interlobar arteries (arrows in b), in the middle lobe and lingula (arrows in c), and in both lower lobes (arrows in d).Download as PowerPointOpen in Image (d) Subsequent angiogram demonstrates slight distortion of the posterobasal segment of the left lower lobe pulmonary artery (arrow) but no evidence of pulmonary embolism. (Fig 1 modified and Figs 1-3 reprinted, with permission, from reference ,12. Localized increase in vascular resistance in a 65-year-old man with dyspnea. Figure 31. 29, No. More distally, the pulmonary arteries were well enhanced. 5, Korean Journal of Radiology, Vol. 43, No. Other CT pulmonary angiographic findings in chronic pulmonary embolism include evidence of recanalization, webs or flaps, and partial filling defects that form obtuse angles with the vessel wall. Viewer. 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). Collateral bronchial artery dilatation is also noted (arrowhead).Download as PowerPointOpen in Image Our CT techniques are shown in the ,Table. 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). After reading this article and taking the test, the reader will be able to: List the diagnostic criteria for acute and chronic pulmonary embolism at CT pulmonary angiography. 44, No. Beam-hardening artifact in a 63-year-old man with respiratory failure. 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