(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 apparent pulmonary embolism is ill defined. Unlike true emboli, however, these apparent abnormalities are not well-defined filling defects. 202, No. 3, 21 March 2013 | International Journal of Legal Medicine, Vol. Viewer. Figure 16. Viewer. CT scan shows streak artifact from dense contrast material within the superior vena cava (arrows). Pulmonary embolism (PE) is a relatively common vascular disease with potentially life-threatening complications in the short term. Unable to process the form. 5, Clinics in Chest Medicine, Vol. CT scan shows complete occlusion of vessels in the left lung (arrowheads) that are smaller than adjacent patent vessels. Indeterminate CT pulmonary angiogram: Why and does it matter?. For intravenous access, introduction of an 18- or 20-gauge catheter into an antecubital vein is preferred. 16, No. (b) CT scan obtained with the standard algorithm does not demonstrate this artifact. 4, Korean Journal of Radiology, Vol. (e) More oblique angiogram of the left pulmonary artery also demonstrates no evidence of pulmonary embolism (arrow).Download as PowerPointOpen in Image Acute central pulmonary embolism in an asymptomatic 87-year-old woman. 6, IEEE Transactions on Biomedical Engineering, Vol. Figure 20b. CT scan shows an acute pulmonary embolus that causes a partial filling defect surrounded by contrast material (railway track sign) (arrow). The apparent pulmonary embolism is ill defined. Current pulmonary CTA techniques involve ever lower doses of contrast medium and radiation along with advanced postprocessing applications to enhance image quality, diagnostic accuracy, and provide added value in patient management. (e) More oblique angiogram of the left pulmonary artery also demonstrates no evidence of pulmonary embolism (arrow).Download as PowerPointOpen in Image Image noise makes the evaluation of segmental and subsegmental vessels difficult and can cause indeterminate CT pulmonary angiography and misdiagnosis of pulmonary embolism (,Fig 21). 3, American Journal of Roentgenology, Vol. Chronic pulmonary embolism in a 27-year-old man with dyspnea. 8, No. Figure 32. Pulmonary embolism CT technique does not use gating. 50, No. 32, No. Viewer. Images of the iliac, femoral, and popliteal veins are obtained 4 minutes after the onset of enhancement from the initial contrast material injection. Figure 25 illustrates the effect of different window settings on detection of pulmonary embolism. Describe the causes of misdiagnosis of pulmonary embolism at CT pulmonary angiography. )Download as PowerPointOpen in Image Tumor embolus in a 78-year-old woman with dyspnea and endometrial stromal sarcoma that invaded the inferior vena cava. 4, American Journal of Veterinary Research, Vol. This artifact can be distinguished from pulmonary embolism by recognizing its nonanatomic, poorly defined, radiating nature (,Fig 26) and can be reduced by flushing the superior vena cava with saline solution using dual chamber injectors. 1, European Journal of Radiology, Vol. 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 Streak artifact in a 35-year-old woman with chest pain. Beam-hardening artifact in a 63-year-old man with respiratory failure. 50 (1): 62-67. (b, c) CT scans obtained immediately superior (b) and inferior (c) to a demonstrate an apparent ill-defined filling defect (arrow) that is too high in attenuation to represent pulmonary embolism. These findings indicate the true nature of the patient’s condition. 30, No. This partial filling defect surrounded by contrast material produces the polo mint sign (arrow). These are important observations because acute pulmonary embolism may be identified even if it is not suspected clinically. 2, American Journal of Roentgenology, Vol. 93, No. 127, No. On occasion, intravascular thrombosis is identified in a pulmonary artery stump. The posterobasal segment of the right lower lobe bronchus is dilated as well as mucus filled. 5, Journal of Thoracic Imaging, Vol. )Download as PowerPointOpen in Image Viewer. CT scan shows a flap (arrow) within a small right interlobar pulmonary artery. Diagnosis of pulmonary embolism with d-dimer adjusted to clinical probability. Figure 30c. Coronal reformatted image of the right interlobar artery and the posterobasal segment of the pulmonary artery demonstrates dense contrast material superior and inferior to a region of poorly enhanced blood (arrow). Figure 35e. (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. 2, Annals of Thoracic and Cardiovascular Surgery, Vol. (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). Figure 8. (d) Subsequent angiogram demonstrates slight distortion of the posterobasal segment of the left lower lobe pulmonary artery (arrow) but no evidence of pulmonary embolism. Figure 11. Arrows indicate collateral bronchial arteries. 36, No. 51, No. The unenhanced or poorly enhanced blood within the affected vessel may mimic pulmonary embolism. More distally, the pulmonary arteries were well enhanced. 31, No. CT scan shows a pulmonary embolus within the posterobasal segment of the right lower lobe artery (arrow). MATERIALS AND METHODS: A multi-detector row spiral CT protocol for the diagnosis of pulmonary embolism was used that consisted of scanning the entire chest with 1-mm collimation within one breath hold. Figure 25c. 21, No. The following document is an updated CT protocol for all of the sites at which TRA-MINW is ... CTA Chest Pulmonary Embolism & Routine CT Abdomen + Pelvis W CTA Chest (pulmonary arterial) & CT Abdomen + Pelvis W (venous) Indication: Evaluate for pulmonary embolism (chest pain, shortness of breath, elevated D-dimer, etc.) For each lung, the main, lobar, segmental, and subsegmental arteries are examined for pulmonary embolism. 11, No. 184, No. This approach helps differentiate between a sharply marginated embolus and an ill-defined artifact. Viewer. 4, 4 January 2014 | The International Journal of Cardiovascular Imaging, Vol. 38, No. 12, No. Viewer. (b) CT scan produced with bone window settings clearly depicts the pulmonary artery catheter. 6, 10 October 2018 | Journal of Medical Imaging and Radiation Oncology, Vol. Small pulmonary emboli could be obscured by a large amount of image noise. Computed tomographic (CT) pulmonary angiography has been evaluated with meta-analysis and has demonstrated sensitivities of 53%–100% and specificities of 83%–100% (,6), wide ranges that are explained in part by technologic improvements over time. (e) More oblique angiogram of the left pulmonary artery also demonstrates no evidence of pulmonary embolism (arrow). 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. CT scan shows unenhanced pulmonary veins (arrows), which can mimic complete occlusive pulmonary embolism. 45, No. 3, American Journal of Roentgenology, Vol. 2, 9 May 2016 | Journal of Medical Imaging and Radiation Oncology, Vol. Transient interruption of contrast enhancement is likely related to inspiration and to unenhanced blood entering the right atrium, right ventricle, and pulmonary arteries from the inferior vena cava just prior to image acquisition (,27). 65, No. 2, 22 September 2015 | Journal of Magnetic Resonance Imaging, Vol. This partial filling defect surrounded by contrast material produces the polo mint sign (arrow). 31, No. (b) CT scan shows acute emboli that affect subsegmental arteries of the laterobasal segment (arrows).Download as PowerPointOpen in Image 41, No. 55, No. In addition, one of the contiguous images often demonstrates adjacent lung or bronchus (,,,,Fig 28). )Download as PowerPointOpen in Image 2, Veterinary Clinics of North America: Small Animal Practice, Vol. Computed Tomography (CT) is the mainstay of diagnostic imaging evaluation of thoracic disorders. adequate enhancement of the pulmonary trunk and its branches. Adjacent beam-hardening artifacts are also seen.Download as PowerPointOpen in Image Partial volume artifact in a 52-year-old woman with dyspnea. Figure 28c. (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. 44, No. (a) Unenhanced CT scan demonstrates subtle regions of hyperattenuation (arrow). (a) CT scan (window width = 400 HU, window level = 40 HU) demonstrates thrombus within the right interlobar artery (arrow). The radiologist needs to determine the quality of a CT pulmonary angiographic study and whether pulmonary embolism is present. 4, © 2021 Radiological Society of North America, EDUCATION EXHIBIT - Continuing Medical Education, Open in Image Partial filling defects due to acute pulmonary embolism are often centrally located, but when eccentrically located they form acute angles with the vessel wall. Mucus plugs in an 83-year-old woman with dyspnea. Note also the medium-sized left pleural effusion and atelectasis. Pulmonary artery stump in situ thrombosis in a 69-year-old man who had undergone right pneumonectomy for lung cancer. Localized increase in vascular resistance in a 65-year-old man with dyspnea. (a) CT scan (window width = 400 HU, window level = 40 HU) demonstrates thrombus within the right interlobar artery (arrow). Motion artifact renders the diagnosis of pulmonary embolism at this anatomic level indeterminate. Figure 14. In addition, a centrally located, hyperattenuating filling defect is occasionally identified at unenhanced CT, a finding that indicates acute central pulmonary embolism (,,,Fig 10) (,22). CT scan shows a large chronic pulmonary embolus in the main and left main pulmonary arteries (arrowhead). Coronal reformatted image of the right interlobar artery and the posterobasal segment of the pulmonary artery demonstrates dense contrast material superior and inferior to a region of poorly enhanced blood (arrow).Download as PowerPointOpen in Image 3, Radiologic Clinics of North America, Vol. (2017) Journal of Medical Imaging and Radiation Oncology. (a) CT scan (lung window) shows composite images of vessels (seagull sign) (arrows). MR pulmonary angiography: Can it be used as an alternative for CT angiography in diagnosis of major pulmonary thrombosis? A partial filling defect surrounded by contrast material, producing the “polo mint” sign on images acquired perpendicular to the long axis of a vessel (,,,Fig 5) and the “railway track” sign on longitudinal images of the vessel (,Fig 6). These intravascular tumors manifest as unilateral, lobulated, heterogeneously enhancing masses at CT (,38,,39). Acute pulmonary embolism in a 58-year-old woman who presented with chest pain and dyspnea. (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. Chronic pulmonary embolism in a 62-year-old man with dyspnea. Viewer. CT scan reveals that the short axis of the right ventricle (dashed line) is wider than that of the left ventricle (solid line), a situation that was caused by acute pulmonary embolism and created right ventricular strain.Download as PowerPointOpen in Image Viewer. 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. (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 30b. CTA Pulmonary Embolism CTA Chest (pulmonary angiogram) Reviewed By: Rachael Edwards, MD; Dan Verdini, MD; Brett Mollard, MD Last Reviewed: July 2019 Contact: (866) 761-4200, Option 1 In accordance with the ALARA principle, TRA policies and protocols promote the utilization of radiation dose reduction techniques for all CT examinations. Figure 24b. Pulmonary CT angiography (CTA) has been firmly established as the modality of choice in suspected acute PE [2, 3]. The artery is enlarged compared with adjacent patent vessels. Figure 25 illustrates the effect of different window settings on detection of pulmonary embolism.Download as PowerPointOpen in Image Note the dilated collateral bronchial artery (arrowhead). 3, Journal of Thoracic Imaging, Vol. (a) CT scan obtained with an edge-enhancing algorithm shows a lung algorithm artifact that mimics acute pulmonary embolism (arrows). (,Fig 1 modified and Figs 1-3 reprinted, with permission, from reference ,12. 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