Imaging Findings in Covid-19. Complications and Mimicking Diseases

Rev Chil Radiol 2020; 26(4) ARTÍCULO DE REVISIÓN Imaging findings in Covid-19. Complications and mimicking diseases

Jaime Álvarez C.1*, Paula Concejo I.1, Concepción Ferreiro A.1, Esther Gálvez G.1, María Azahara Hoyas G.1, Iñigo Zubiaguirre T.1, Cristian Rodríguez R.1, Wilmar Ocampo T.1, Francisca Sánchez O.1, Manuel Martínez P.1

1. Radiologist, Radiodiagnosis Services, Hospital Universitario Severo Ochoa, Leganés-Madrid, España.

Hallazgos de imagen en Covid-19. Complicaciones y enfermedades simuladoras

Abstract: Given the current pandemic caused by SARS-CoV-2, the scientific community is making an effort to share knowledge of this emerging disease. To contribute to this effort, we have done a compre- hensive review of the clinical history and imaging tests in patients affected by COVID-19 in our institution, one of the most affected by the pandemic in the Community of Madrid (Spain). The aim of this review is to describe the radiological findings in the lungs and show the most frequent extrapulmonary pathology as well as some entities that may be confused with COVID-19 will be discussed. Radiologists should become familiar with these imaging features of COVID-19 to design specific imaging protocols that allow prompt diagnosis and treatment. Keywords: Complications; COVID-19; Extrapulmonary; Mimickers; Pneumonia; Thrombosis.

Resumen: Ante la situación actual de pandemia producida por el SARS-CoV-2, la comunidad científica está realizando un esfuerzo para compartir el conocimiento de esta enfermedad emergente. Para contribuir a este esfuerzo, hemos realizado una revisión de las historias clínicas y de las pruebas de imagen en pacientes diagnos- ticados de la COVID-19 en nuestro centro, uno de los más afectados por la pandemia de la Comunidad de Madrid (España). El objetivo de esta revisión es describir las alteraciones radiológicas pulmonares y mostrar la patología extrapulmonar más frecuente y entidades simuladoras de la COVID-19. Los radiólogos deben familiarizarse con estas características de imagen de la COVID-19, de forma que se puedan diseñar protocolos de imagen específicos para cada una de ellas de cara a un diagnóstico y tratamiento oportuno. Palabras clave: Complicaciones; COVID-19; Extrapulmonar; Neumonía; Simuladoras; Trombosis.

Álvarez J, et al. Hallazgos de imagen en Covid-19. Complicaciones y enfermedades simuladoras. Rev Chil Radiol 2020; 26(4): 145-162. *Email: Jaime Álavrez C. / [email protected] Work sent 01 June 2020. Accepted for publication 17 August 2020.

Introduction Acute respiratory disease coronavirus 2019 (CO- World Health Organization declared a worldwide VID-19, formerly known as 2019-nCoV) is a highly state of public health emergency, and on March 11 infectious disease caused by the Severe Acute it was declared a pandemic2. As of June 1, 2020, a Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) total of 6,246,042 cases of COVID-19 were already first described in Wuhan, capital of Hubei Province confirmed with 374,452 deaths worldwide, of which in China in December 2019 and has spread around 239,638 cases with 27,127 deaths corresponded to the world very rapidly1. On January 30, 2020, the cases declared in Spain3.

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La Comunidad Autónoma de Madrid ha sido una opacities in posterior segments of the lower lobes (a deThe Autonomous Community of Madrid has been fundamental hallmark of COVID-19) with evolution to one of the most affected areas. Of the almost 50 mainly subpleural subsegmental patchy consolida- hospitals in the Autonomous Community of Madrid, tions5. In addition, other forms of involvement have our center, the Severo Ochoa Hospital, has been one been described, such as the cobblestone-like pattern of the ones that has received the largest number of (crazy paving), the halo sign and the formation of cases, attending a population of 190,000 people and subpleural bands5,6. Figure 1 describes the main treating 3,562 patients due to COVID -19, of which 2,699 radiological patterns on computed tomography (CT) were admitted, quadrupling the maximum number of of lung involvement. which the hospital is projected for admitted patients during the pandemic. 2. Extrapulmonary involvement We have carried out a review of the medical records Cases of pneumomediastinum and pneumothorax and imaging tests performed on patients treated for associated with lung involvement due to COVID-19 COVID-19 in our hospital, focusing on the radiological have been identified, although the mechanism is findings of extrapulmonary complications and the unknown. Once these complications are observed, detection of associated pathologies. Also included these patients have to be closely monitored be- are entities that can mimick COVID-19 involvement cause it can be a possible indicator of worsening in the imaging and cause diagnostic errors. of the disease. Therefore, early imaging and timely The review will be structured in the following treatment of COVID-19 complications can improve sections: the therapeutic effect and reduce mortality7. 1. Patterns of lung involvement. 2. Extrapulmonary involvement. 3. Complications related to a prothrom- Pneumomediastinum botic state (thrombotic and embolic phenomena). 4. Spontaneous pneumomediastinum is defined by Complications related to anticoagulant treatment. 5. the presence of extraluminal gas in the mediastinum Mimicking diseases. of non-traumatic origin without associated lung disease. It is a self-limited condition and the prognosis 1. Patterns of lung involvement depends on the underlying cause8. The presence of The new COVID-19 epidemic is mainly associa- air in the mediastinum is explained by air dissecting ted with pulmonary disease, although associated that extends centripetally through the Broncho vas- pre-existing respiratory comorbidities are one of cular sheaths, serous structures and adipose tissue the least important risk factors compared to hyper- due to an increase of the intrathoracic pressure that tension, heart disease, obesity, male sex or age4,5. determines alveolar rupture8,9. Alveolar rupture occurs The typical pattern of pulmonary involvement is the in the presence of elevated intra-alveolar pressure presence of peripheral and subpleural ground-glass or damage to the alveolar walls.

Figure 1: Typical chest CT patterns of COVID-19 viral involvement: a. Ground-glass opacities. b. Consolidations. c. Cobblestone pattern. d. Halo sign. e. Subpleural bands.

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The chest radiograph is the routine imaging test ventilation and central venous catheter insertion, for the diagnosis of pneumomediastinum visualized consisting of alveoli rupture as a consequence of as a double line that draws the mediastinal contour. pulmonary overexpansion, with alveolar air outflow CT is the gold standard test, although it is reserved and finally formation of pneumomediastinum, pneu- for doubtful or complicated cases (Figure 2)8. mothorax and emphysema (Figure 3)11. Lung-protective ventilation, prone position ventilation, sedation, and adequate analgesia are Pneumothorax part of the management of patients with COVID 19. An association between COVID-19 and spon- Approximately 3.2% of patients require intubation taneous pneumothorax has been described, but and invasive ventilation at some point in the course its prognostic importance is unknown12; in our of the disease10. Barotrauma occurs as a common center we did not identify cases of spontaneous complication in patients undergoing mechanical pneumothorax.

Figure 2: 65-year-old woman with lung involvement due to COVID-19. On the third day after admission, she presented clinical and laboratory worsening with an increase in LDH and D-Dimer. CT angiography of the chest, mediastinal window (a) and pulmonary (b) evidenced unilateral right pulmonary thromboembolism (arrowhead), pneumomediastinum (arrows) and multifocal diffuse bilateral ground-glass opacities.

Figure 3: A 49-year-old man, obese, with COVID-19 pneumonia, presents sudden onset of dyspnea and elevated D-Dimer. CT angiography of the chest, lung window (a and b) and mediastinum (c); evidence of right unilateral pulmonary thromboembolism (arrowhead), pneumomediastinum (*), subcutaneous emphysema (black arrow), minimal left pneumothorax (white arrow) and multifocal bilateral ground-glass opacities with pulmonary involvement around 50%.

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Pneumothorax can be primary (with no known un- lism (PE) has been described in patients affected derlying cause) or secondary spontaneous to pre-existing by COVID-19, up to 23%, with a higher incidence lung disease. Spontaneous rupture of a subpleural bulla 12 days after the onset of symptoms. No clear as- is the most frequent cause of primary spontaneous and sociation has been seen between the extent of lung most secondary ones are iatrogenic due to aspiration, involvement and the risk of developing thrombotic thoracentesis, and positive pressure. Generally, the phenomena, but it has been seen in patients with visualization of free air in the radiographic study is suffi- poor clinical evolution of the infection16. In a patient cient for the diagnosis, although in small pneumothorax with hypoxia and increasing D-dimer values while the or in critically ill patients, the diagnosis may require CT13. rest of the analytical parameters normalize (ferritin, LDH, C-reactive protein), a complication with PE 3. Complications related to a prothrombotic state should be suspected17. Current guidelines recommend As more is known about the pathophysiology of chest CT as a diagnostic tool to assess the pattern COVID-19 infection, some of the associated findings or of involvement and lung extension. However, due to complications seen in these patients are explained. The the increasing incidence of PE due to coagulopathy infection is related to an identified prothrombotic state associated with SARS-CoV-2 infection, some authors and elevated levels of D-Dimer14. It has been postulated propose performing chest CT angiography to evaluate that this prothrombotic state is secondary to a release the lung and the presence of thrombus (Figure 4)18, of pro-inflammatory cytokines that induce the activation as well as to evaluate other complications such as of endothelial and mononuclear cells with expression of overload of the right cavities (Figure 5) that can result tissue factor that leads to the activation of coagulation in respiratory distress, especially in those patients with and thrombin formation. Free thrombin circulation, not risk factors (patients admitted to the ICU, mechanical controlled by natural anticoagulants, can activate platelets ventilation, etc.)16,18. and cause thrombosis15. Thromboembolic event rates Initial treatment is usually systemic anticoagu- and the use of increased thromboprophylaxis in patients lation until the thrombus resolves19,20. Thrombolysis with COVID-19 are therefore a topic of great interest. or thrombectomy is reserved for patients in shock, However, the clinical manifestations of this procoagulant hypotension, or with other signs of systemic hypo- tendency are poorly defined14,15. perfusion caused by pulmonary embolism; surgery (lobectomy) is only used in those cases where there Pulmonary thromboembolism (PE) is no clinical improvement, suspicion of gangrene, A higher prevalence of pulmonary thromboembo- massive hemoptysis, or pulmonary necrosis19.

Figure 4: 26-year-old woman with a history of oral contraceptive treatment, symptoms of dry cough and dyspnea (suspected COVID-19 infection), sinus tachycardia, S1Q3T3 ECG pattern and D-Dimer elevation. CT angiography of the chest, mediastinum (a) and lung (b); evidence of bilateral pulmonary embolism with saddle thrombus (arrowhead) and right chamber overload. Faint bilateral ground-glass opacities with pulmonary involvement in around 25% (arrow).

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Figure 5: A 50-year-old man with cardiovascular risk factors and chronic liver disease presents with a one-week history of cough, mid-thoracic pain, anatomic symptoms, and elevation of the D-Dimer. CT angiography of the chest, mediastinum (a, b) and lung (c); evidence of bilateral pulmonary embolism with saddle thrombus (arrows) and right chamber overload (*). Bilateral ground-glass opacities with pulmonary involvement around 25%.

Aortic floating thrombi Aortic floating thrombi (AFT) are a rare entity fre- among hospitalized patients is 0.9%, reaching up to quently associated with atherosclerotic and aneurysmal 15% to 32% among ICU patients24,25. This incidence disease21,22. In those patients without arterial vascular increases in patients with COVID-19 disease, being disease, due to the high flow and aortic pressure, the most frequent location of the thrombus mainly the presence of AFT is rare, in these cases they are distal calf muscles and infrapopliteal territories, they usually associated with hypercoagulable states and are also described in the iliac-femoral-popliteal axis hematological diseases, after instrumental procedu- (Figure 7)26. res or steroid treatment. In general, they are more Acute infections are associated with a transient frequent in the descending thoracic aorta, as well as increase in the risk of venous thromboembolic events27, in the aortic arch (Figure 6)21,22,23. The test of choice it is postulated that the production of procoagulant is CT angiography due to its wide availability and factors such as tissue factor and clot degradation since it allows evaluation of the aorta in its entirety, factors such as D-dimer, are possible mechanisms supra-aortic trunks, as well as the pulmonary vessels of thrombosis, although a relationship has not been and the existence of concomitant embolic ischemic established with DVT26. Another possible favorable phenomena in other locations21,22. Due to the high factor that could also explain the involvement of the embolic risk, treatment is essential, although there upper extremities, including thrombophlebitis of the is no established protocol, with medical treatment external jugular vein (Figure 8) is the use of a con- (anticoagulation and thrombolytic drugs) being the first tinuous positive ventilator pressure in the airways, therapeutic option, reserving surgery (thrombectomy, which can compress the superficial or deep vessels of thromboendarterectomy and aortic replacement) or the upper extremities26; all the patients in our hospital endovascular prosthesis placement for those cases with upper limb involvement were in fact receiving that do not improve with medical treatment or when continuous positive pressure therapy, and some of there are recurrences or those patients with risk them were users of central lines. factors21,22,23. Ultrasound is usually the initial study, especially in patients with central lines. They behave like any Deep vein thrombosis and thrombophlebitis thrombosed venous structure. In CT or MRI studies It is known that ICU patients are at greater risk of with contrast, the thrombosed vein is enlarged and developing deep vein thrombosis (DVT); in the abs- with peripheral uptake that corresponds to the venous ence of adequate prophylaxis, its general incidence wall28.

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Figure 6: 89-year-old male diagnosed with COVID-19 with a torpid progress and increased D-Dimer. CT angiography of the chest, lung window (a); Ground-glass opacities with 50-75% involvement of the lung parenchyma. Mediastinal window axial slice (b) and coronal (c) floating thrombi in aortic arch and descending thoracic aorta (arrows).

Figure 7: 77-year-old man diagnosed with COVID-19 with a torpid progress and increased D-Dimer. Abdominopelvic CT with iv contrast (a.) Filling defect of the common, superficial and deep femoral veins, in relation to DVT. (arrows). Chest CT, lung window (b); Ground-glass opacities with pulmonary involvement around 25%.

Figure 8: 48-year-old woman with no relevant history with symptoms of dry cough and dyspnea (suspected COVID-19 infection) and elevated D-Dimer. Chest CT angiography, mediastinal window (a.) Shows a filling defect in the right anterior and internal jugular vein compatible with thrombosis (arrows). Lung window (b); predominantly multiple parenchymal consolidations are seen in RLL.

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Unfortunately, no data is yet available on the and hyper-acute treatment is the key to minimi- prognosis of patients who develop DVT during a zing mortality and morbidity in patients with acute SARS-COV-2 infection, so further studies should stroke. “Stroke units” must be aware that COVID-19 investigate how the two conditions interact with patients can present with strokes and must have each other and their possible impact on recovery. the appropriate personal protective equipment for However, considering these preliminary data, our each suspected patient32. institution administers anticoagulant doses of low molecular weight heparin (LMWH) in hospitalized Multiple cerebral infarcts patients with COVID-19, after monitoring the results There are emerging global reports of coagulopathy of coagulation tests and kidney and liver function26. in the context of COVID-19, including pulmonary embolism, multiple cerebral infarcts (Figure 10), Ischemic stroke and limb ischemia33. A recent publication identified Although ischemic stroke has been recognized antiphospholipid antibody in a COVID-19 patient with as a complication of COVID-19 (usually with severe significant coagulopathy. These antibodies can also disease)29 the mechanisms and phenotype are arise transiently in patients with critical illnesses and not yet definitive, although it has been suggested various infections. that COVID-19 could stimulate the production of The presence of these antibodies can rarely lead antiphospholipid antibody30 as ischemic stroke to thrombotic events that are difficult to differentiate mechanism (Figure 9). from other causes of multifocal thrombosis in criti- Early therapeutic anticoagulation with LMWH cally ill patients, such as disseminated intravascular could also be beneficial in reducing thromboem- coagulation, heparin-induced thrombocytopenia, and bolism in patients with ischemic stroke associated thrombotic microangiopathy30. with COVID-19, but must be balanced with the risk It has also been proposed that coagulopathy may of intracranial hemorrhage, including hemorrhagic portend a poor prognosis in patients with COVID-19 transformation of acute infarction31. Early diagnosis disease.

Figure 9: A 77-year-old man with COVID-19 pneumonia presents symptoms of facial and left brachial paresis. Cranial CT without iv contrast (a). Hypodense cortical subcortical lesion in the right cerebral hemisphere compatible with acute ischemia in the territory of the right middle cerebral artery (*). CT with iv contrast, Willis polygon with 3D reconstruction (b) shows obstruction of the right M2 segment (arrow). Chest CT lung window showing extensive areas of bilateral ground- glass and cobblestone pattern.

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Figure 10: 56-year-old male, SARS-CoV-2 positive, admitted to the ICU due to severe respiratory failure, after removal of sedation, left hemiparesis with asymmetric reflexes was clear. Cranial CT without iv contrast (a and b). Ischemic lesion in the territory of the right middle cerebral artery and left posterior cerebral artery. PA chest radiograph (c) shows bilateral peripheral patchy opacities in both hemithorax.

Mesenteric ischemia / ischemic colitis developed for the local administration of thrombolytic Intestinal ischemia, mainly mesenteric artery agents, as well as mechanical thrombectomy37. thrombosis and, to a lesser extent, ischemic colitis, is Splenic infarction is the result of the occlusion of a a rare condition that constitutes one of the abdominal splenic arterial branch, caused mainly by thromboem- emergencies with the worst prognosis and can be a bolic disease or by infiltrative hematological diseases. thromboembolic complication secondary to the hyper- They are classically seen as wedge perfusion defects coagulable state associated with COVID-19. It presents in the parenchyma, although when they are multiple high rates of morbidity and mortality, therefore, early they can fuse and lose this morphology. The key is diagnosis and prompt management are essential34. the extension of the abnormal parenchyma area to In this sense, imaging tests have an important role, the intact capsule (Figure 13). Acute infarcts can be since neither the symptoms nor the laboratory tests are complicated by superinfection, subcapsular hema- specific. Currently, CT is the initial imaging technique of tomas, or splenic ruptures. A chronic infarct loses choice for the diagnosis of suspected acute intestinal volume with focal atrophy and can calcify38. ischemia and, in addition, it allows the exclusion of other causes of acute abdominal pain (Figure 11)35. 4. Complications related to anticoagulant treatment Finally, the small intestine may also be an important Anticoagulants, such as heparin sodium and LMWH, site of entry or interaction for SARS-CoV-2, as ente- are currently used for the treatment and prevention rocytes are rich in angiotensin converting enzyme of thromboembolic disease secondary to COVID-19 (ACE-2) receptors. Initial gastrointestinal symptoms involvement. Bleeding is estimated to be an often that appear early in the course of COVID-19 support serious complication of anticoagulant therapy, in up to this hypothesis36. 4% of treated patients39. Gastrointestinal bleeding is a frequent form of complication that usually subsides Ischemic lesions of solid organs after correcting the coagulation state. Other frequent Renal infarction is an underdiagnosed entity due forms of serious hemorrhagic complications are the to its non-specific clinical and laboratory presenta- abdominal wall hematoma, especially of the muscular tion. Due to the wide availability of CT, the incidental compartments of the rectum sheath (Figure 14) or diagnosis of renal infarctions is increasing, which the iliopsoas muscle (Figure 15) with opening to the favors early diagnosis and treatment, thus reducing retroperitoneum (Figure 16), both of which are those, the time of renal ischemia (Figure 12)37. Due to its low that with greater frequency require urgent percuta- frequency, there is no established treatment protocol. neous treatment. Anticoagulation is insufficient to reduce ischemia, Risk factors include, in addition to anticoagulation for so more aggressive measures such as systemic the prothrombotic state induced by COVID-19, specific thrombolysis are chosen, although it increases the comorbidities (severe heart disease, liver dysfunction, risk of bleeding. Endovascular techniques have been kidney failure, hypertension, cerebrovascular disea-

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Figure 11: A 70-year-old man with COVID-19 lung involvement, presents with acute abdominal pain, rectal bleeding, increased CRP and D-dimer. Abdominal CT with iv contrast, lung window in the middle fields shows extensive and bilateral ground-glass involvement predominantly posterior. Section at the level of the mesogastrium (b) and coronal MPR reconstruction (c) shows circumferential thickening of the wall of the left colon with increased attenuation of the adjacent fat suggestive of ischemic colitis.

Figure 12: A 78-year-old man with pulmonary involvement due to COVID-19, presents with acute abdominal pain, impaired kidney function and elevated D-Dimer. Abdominal CT with iv contrast (a). Left renal infarction (arrow). Lung window at the level of the lower fields shows a cobblestone pattern, subpleural bands and bronchiectasis.

Figure 13: A 70-year-old man with COVID-19 parenchymal involvement, presents with acute abdominal pain, fever, and D-Dimer elevation. Abdominal CT with iv contrast. Middle field lung window shows extensive and bilateral ground-glass involvement. Soft tissue window section in the upper hemiabdomen (b) and coronal MPR reconstruction (c) showing splenic triangular hypodensity compatible with infarction (arrow).

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Figure 14: 57-year-old woman with pulmonary involvement due to COVID-19, massive PTE and treatment with heparin, sudden drop in hemoglobin. Abdominal CT with iv contrast, lung window (a) shows patchy areas of ground-glass. In abdominal slices (b) hematoma in the anterior rectus muscle and the left obliques of the abdomen (*) extending to the pelvis that depends on the left inferior epigastric artery. Pre and post embolization angiography (c and d) of active bleeding from the left lower epigastric artery (Arrows).

Figure 15: A 71-year-old man with COVID-19 lung involvement and right unilateral PE under treatment with LMWH at anticoagulant doses, presents with hypotension and a decrease of 3 mg / dl in hemoglobin. Abdominal CT without iv contrast. (a) Hematoma of the ilio-psoas muscle (*) on the left side. Lung window in the middle fields (b) shows a cobblestone pattern in the right hemithorax, predominantly posterior. Pre-embolization arteriography (c) of active artery bleeding left distal lumbar (Arrows), (d) post treatment with embolization liquid.

Figure 16: A 57-year-old woman with a history of AF, admitted for pulmonary involvement due to COVID-19 and anticoagulant treatment for right DVT, presents with hypotension and a decrease of 4 mg / dl in hemoglobin. Abdominal CT with iv contrast (a). Extensive hematoma of the left psoas (*) with increased attenuation of retroperitoneal fat. Lung window in middle fields (b) showing predominantly peripheral pulmonary consolidation in both lower lobes and patchy areas of ground-glass density. Arteriography pre (a) and post-embolization (b) of active bleeding of the left distal lumbar artery and iliopsoas artery (Arrows).

154 Rev Chil Radiol 2020; 26(4) ARTÍCULO DE REVISIÓN se, and patients receiving long-term hemodialysis), ning) or an alveolar (partial occupation of alveoli) use of concurrent medications (mainly non-steroidal process and is a common manifestation of multiple anti-inflammatory agents and diuretics), duration of lung diseases. In this review we describe a series of treatment, intensity of anticoagulant effect, and age entities with characteristics of ground-glass opacity of the patient40. The diagnostic method of choice is on pulmonary CT that can mimick lung parenchymal abdominal CT since, in addition to assessing the size involvement in COVID-19, such as pulmonary edema, and location of the hematoma, it verifies the existence diffuse alveolar hemorrhage, non-specific interstitial of active bleeding and identifies the artery causing pneumonia (NSIP), hypersensitivity pneumonitis (HP), the bleeding. In the event of failure of conservative atypical pneumonias, radica (radiation) pneumonitis, treatment or hemodynamic instability, endovascular metastasis, etc. treatment is indicated for embolization of bleeding41. In low-location hematomas of the rectus sheath, em- Pulmonary edema bolization of the ipsilateral inferior epigastric artery Pulmonary edema is a very common cause of is usually sufficient to control bleeding (Figure 14d), diffuse ground-glass opacity, but it is characterized by a while those of high location sometimes require dis- perihilar predominance and in the basal regions of the tal embolization of the ipsilateral internal mammary lower lobes, usually symmetric and with preservation artery. In the case of spontaneous retroperitoneal of the peripheral portions of the lung, unlike COVID-19. hematomas, the arteries involved are the lumbar It is associated with other suggestive signs, such as arteries and the iliolumbar artery (Figures 15d, 16d). septal thickening that reflects the dilated lymphatic The use of liquid/adhesive materials is recommen- vessels and thickening of the interlobular septa (Figure ded, whose therapeutic effect is independent of the 17). A common finding that supports this diagnosis patient’s coagulation status42. is associated pleural effusion, frequently bilateral46.

5. Mimicking diseases Hemorragia alveolar difusa A wide variety of CT findings have been described Diffuse alveolar hemorrhage is an emergency that is in lung involvement in COVID-19 disease. However, defined as the presence of blood in the alveolar spaces. It all studies indicate that the main characteristic on occurs due to damage in the pulmonary microcirculation lung CT is the presence of ground-glass opacities, (capillaries, arterioles and alveolar venules) and can be of typically with a peripheral and subpleural distribu- pulmonary origin, for example, in infection or of a systemic tion, with involvement of multiple lobes, particularly cause as occurs in systemic vasculitis. Clinically, it can the lower lobes1,43,44,45. The ground-glass pattern manifest as hemoptysis, dyspnea, acute-onset cough, 47,48 represents either an interstitial (interstitial thicke- and anemia . It is also characterized by perihilar and

Figure 17: An 81-year-old man with multiple cardiovascular risk factors, consultation for cough and progressive dyspnea for 2 weeks (suspected SARS-CoV-2 infection). CT angiography of the chest, mediastinum window (a) and lung (b), shows cardiomegaly, ground-glass opacity of perihilar distribution, thickening of fissures and bilateral pleural effusion.

155 Rev Chil Radiol 2020; 26(4) bilateral ground-glass opacities of sudden onset and pattern in a peripheral location with involvement of that progressively converge respecting the vertices and the middle and lower fields (Figure 19). Sometimes the periphery of the lungs, without having a subpleural we see a clear improvement in the imaging findings predominance (Figure 18). In the acute phase, it can be after steroid treatment. If the disease progresses, ho- indistinguishable from pulmonary edema or diffuse lung neycombing or traction bronchiectasis can be seen50. infection49. At 48-72 hrs after the episode, a reticular pattern is produced and if there is no recurrence of bleeding, the Hypersensitivity pneumonitis image can return to normal within 1-2 weeks. Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis, is a granulomatous in- Nonspecific interstitial pneumonia (NSIP) flammatory disease of the lungs caused by inhalation Nonspecific interstitial pneumonia (NSIP) is an of antigenic organic fumes or particles51. In the case interstitial disease that affects the lung parenchyma of the bird keeper’s lung, they are particles that are of unknown etiology. The prognosis of this entity is usually found in the epithelium, the dust that covers better than that of other interstitial diseases such as the feathers or the feces of birds52. The disease can the usual interstitial pneumonia (UIP) or desquamative present as an acute, subacute or chronic disease. interstitial pneumonia (DIP). Chest CT is the imaging Acute and subacute HP episodes generally resolve test of choice for its study since in most cases the chest after cessation of antigen exposure once the diagno- X-ray is normal50. It is characterized by a ground-glass sis is established; Corticosteroids are used in early

Figure 18: 48-year-old woman with symptoms of fever, dyspnea and mild hemoptysis, peripheral blood smear compatible with acute leukemia. PA chest x-ray on admission (a) shows LUL and retrocardiac opacities. Portable control chest X-ray at 1 hour (b) shows radiological worsening. Chest CT, lung window (c), shows ground-glass opacities and consolidation. Interlobular septal thickening is not observed. Finding compatible with acute diffuse alveolar hemorrhage, given the clinical context.

Figure 19: Woman with polymyosistis and diagnosis of NSIP under treatment with corticosteroids, consultation for cough without dyspnea (suspected SARS-CoV-2 infection). Previous lung CT from December 2018, without iv contrast. Lung window in lower fields (a) Fine reticular pattern and ground-glass with basal distribution without fibrotic component. Lung CT at entry to the level of upper (b) and lower (c) fields, discrete reticular pattern probably residual and inconclusive for COVID-19, with preservation of upper fields.

156 Rev Chil Radiol 2020; 26(4) ARTÍCULO DE REVISIÓN stages to accelerate healing or in severe or advanced Post-Actinic Pneumonitis stages that can be progressive and irreversible51. On Radiotherapy-induced lung damage manifests chest CT, the combination of a mosaic pattern with itself differently radiologically, depending on the time areas of ground-glass and centrilobular nodules is elapsed since the completion of treatment. In the early highly suggestive of the diagnosis (Figure 20)53. A stages, between 1 and 3 months after radiotherapy; in careful environmental and occupational history and the late or chronic phases, developed later and with establishment of exposure to a known inciting antigen stabilization over 12-15 months, the findings are called are key players in making the diagnosis of HP. radica (radiation) fibrosis. It occurs in <1% of cases and is dose dependent, being constant from 40 Gy57. Atypical pneumonia It manifests as cough and dyspnea 3 months after The group of atypical pneumonia is made up of receiving radiotherapy, although the time of onset is pneumonia caused by viruses, Pneumocystis jirovecii, variable. Not only is CT better able to delineate paren- and atypical bacteria (Legionella pneumophila, Myco- chymal changes, but it often demonstrates localized plasma pneumoniae, and Chlamydia pneumoniae). changes in the irradiated field, facilitating diagnosis. On chest CT, atypical pneumonias produce bilateral, The two most common findings are ground-glass extensive and often symmetrical pulmonary alterations opacities and / or airspace consolidation (Figure 22)58. with a ground-glass pattern54. Pneumocystis jirovecii pneumonia was the most Lung metastases common infection in patients with Acquired Immuno- The typical radiological findings of pulmonary deficiency Syndrome (AIDS), but it has been replaced metastases consist of multiple nodules of varying size by bacterial infection since the introduction of its pro- and diffuse thickening of the interstitium (Figure 23). phylaxis. Non-HIV patients typically present more acute Ground-glass opacity around the mass (halo sign on symptoms with fever and hypoxemia, while HIV patients chest CT) can be seen when fragility of neovascular frequently present a prodrome of 2-3 weeks with low- tissue leads to vessel rupture, as in metastases from grade fever, weight loss, dyspnea, and malaise. The choriocarcinoma and angiosarcoma, as well as tumor most common finding on CT is ground-glass opacities growth along the alveolar walls as in adenocarcinomas with a symmetrical distribution, a predominance of the of gastrointestinal tract tumors59. upper lobes having been described (Figure 21). This finding may be associated with other alterations including Carcinomatous lymphangitis consolidations, septal thickening, and thin-walled cysts Carcinomatous lymphangitis constitutes a pattern that can lead to spontaneous pneumothorax. Definitive of tumor spread through the pulmonary lymphatic ves- diagnosis requires identification of the organism from sels, being a factor of poor prognosis in terms of the respiratory specimens with fluorescent antibody staining response to chemotherapy and survival. 80% of cases 56 or polymerase chain reaction (PCR) . are caused by adenocarcinomas, the most common

Figure 20: 47-year-old man with dyspnea on moderate exertion, 2 weeks, (suspected SARS-COV-2 infection). Epidemiological history of contact with birds. PA chest radiograph (a) shows diffuse opacities in upper and middle fields. Axial chest CT (b) Ground-glass opacities associated with centrilobular ground-glass nodules predominantly in upper fields. PA chest radiograph (c) Radiological improvement of the pulmonary pattern after administration of corticosteroids. Finding compatible with HP.

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Figure 21: A 32-year-old man with moderate exertion dyspnea for 3 weeks, (suspected SARSCOV-2 infection). Epidemiological history of HIV with severe immunosuppression. PA chest radiograph (a) shows diffuse pulmonary opacities. Axial chest CT (b) Ground-glass opacities associated with symmetrical distribution of centrilobular ground-glass nodules. PCR-coronavirus (negative) and PCR- Pneumocystis jirovecii (positive).

Calcified lung nodules Calcified multiple pulmonary nodules occur in a wide variety of diseases, and on chest radiographs they may mimic localized patchy pulmonary opacities. There are multiple processes that condition the appearance of calcified pulmonary nodules (Figure 25). Thus, they appear in the reparative phases of inflammatory processes (TB, chickenpox), benign and malignant tumors (hamartomas, Epithelioid heman- gioendothelioma, metastasis), inhalation diseases (pneumoconiosis of coal workers and silicosis), me- tabolic diseases (kidney failure, hypercalcemia) and processes of unknown origin (alveolar microlithiasis)62.

Conclusion Radiological imaging plays a very relevant role Figure 22: A 57-year-old woman with a history of infiltrating in the diagnosis and follow-up of patients with CO- ductal carcinoma of the right breast. In the 8th week after the VID-19 disease. The most common findings on chest completion of radiotherapy, she presented with symptoms radiographs and chest CT include multifocal bilateral of dyspnea and cough for 2 weeks (suspected SARS-CoV-2 ground-glass opacities and predominantly periphe- infection). Chest CT, lung window (a) shows ground-glass opacities in the upper right anterior lobe (Arrow). rally distributed irregular consolidations. In addition to pulmonary involvement, it is relevant to identify other associated findings, such as extra-parenchymal pulmonary involvement, complications secondary to the prothrombotic state given the high incidence of thrombotic and embolic phenomena, as well as hemorrhagic complications due to anticoagulant treatment. tumors being the lung, breast, colon and stomach60. Likewise, entities that begin with a pulmonary pattern Chest CT findings include smooth or nodular thicke- in ground-glass opacities should be included in the ning of the interlobular septa and thickening of the differential diagnosis. All of these features can aid peribronchovascular and subpleural interstitium, as rapid diagnosis, guide clinical decision-making, and well as mediastinal and hilar adenopathy, and pleural monitor the progression of COVID-19 disease. Special effusion (Figure 24). It can occur both unilaterally and attention should be paid to the role of radiologists in bilaterally61. the fight against this new infectious disease.

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Figure 23: A 72-year-old man with a history of renal carcinoma undergoing chemotherapy with cough and dyspnea for 3 days (suspected SARS-COV-2 infection). PA chest radiograph (a) shows faint opacities in LLL and LUL (arrows). CT of the chest, lung window and MPR reconstruction in coronal (d) and axial (d) planes, shows multiple nodules in both hemithorax suggestive of metastasis.

Figure 24: 57-year-old woman with a history of infiltrating ductal carcinoma of the right breast and carcinomatous lymphangitis. CT angiography of the chest, mediastinal window (a) and lung window (b) shows nodular fissure thickening (arrowhead) and interlobular septa, ground-glass opacities or consolidation (*) with a right unilateral distribution. Bilateral pleural effusion is also seen (Arrow).

Figure 25: 30-year-old woman with no relevant history with one-week symptoms of cough and general malaise (suspected SARS-COV-2 infection). PA chest radiograph (a) shows multiple subcentimeter pulmonary nodules in both hemithorax predominantly in the upper lobes. CT chest reconstruction MPR coronal (b) and axial (c) lung window confirms these findings.

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Bibliography Angiografía con tomografía computarizada: resultados 1. Zhu N, Zhang D, Wang W, Li X, Yang B, Song J, et al. preliminares (citado 22 de mayo de 2020). JNNPR. A Novel Coronavirus from Patients with Pneumonia in 2019; 5(6): 569-668. Disponible en: https://revistas. China 2019. N Engl J Med. 2020 febrero 20; 382(8): proeditio.com/jonnpr/article/view/3689 727-733. 18. Revel M-P, Parkar AP, Prosch H, Silva M, Sverzellati 2. WHO Team. Nuevo coronavirus 2019 (citado 28 de N, Gleeson F, et al. COVID-19 patients and the radio- mayo de 2020). Disponible en: https://www.who.int/es/ logy department-advice from the European Society emergencies/diseases/novel-coronavirus-2019 of Radiology (ESR) and the European Society of 3. Ministerio de Sanidad. Consumo y Bienestar Social- Thoracic Imaging (ESTI). Eur Radiol. 2020 abril 20; Professionals-Situación actual Coronavirus (citado 21 30: 4903-4909. de mayo de 2020). Disponible en: https://www.mscbs. 19. Chaaya G, Vishnubhotla P. Pulmonary Vein Thrombosis: gob.es/en/profesionales/saludPublica/ccayes/alerta- A Recent Systematic Review (citado 22 de mayo de sActual/nCov-China/situacionActual.htm 2020). Cureus. 2017; 9(1): e993. Disponible en: https:// 4. Chung M, Bernheim A, Mei X, Zhang N, Huang M, Zeng www.ncbi.nlm.nih.gov/pmc/articles/PMC5323025/ X, et al. CT Imaging Features of 2019 Novel Corona- 20. Barreiro TJ, Kollipara VK, Gemmel DJ. Idiopathic virus (2019-nCoV). Radiology. 2020 febrero 4; 295(1): pulmonary vein thrombosis? (citado 22 de mayo de 202-207. 2020). Respirol Case Rep. 2017 octubre 24; 6(1): 5. Lupia T, Scabini S, Mornese Pinna S, Di Perri G, De e00277. Disponible en: https://www.ncbi.nlm.nih.gov/ Rosa FG, Corcione S. 2019 novel coronavirus (2019- pmc/articles/PMC5757585/ nCoV) outbreak: A new challenge. Journal of Global 21. Kim SD, Hwang JK, Lee JH, Cho HJ, Sung GY, Moon Antimicrobial Resistance. 2020 junio 1; 21: 22-27. IS, et al. Free Floating Thrombus of the Aorta: An 6. Ye Z, Zhang Y, Wang Y, Huang Z, Song B. Chest CT Unusual Cause of Peripheral Embolization. Journal manifestations of new coronavirus disease 2019 (CO- of the Korean Surgical Society. 2011 marzo 1; 80(3): VID-19): a pictorial review. (citado 21 de mayo de 2020). 204-211. Eur Radiol. 2020 marzo 19; 30(8): 4381-4389. Disponible 22. Weiss S, Bühlmann R, von Allmen RS, Makaloski V, en: https://doi.org/10.1007/s00330-020-06801-0 Carrel TP, Schmidli J, et al. Management of floating 7. Zhou C, Gao C, Xie Y, Xu M. COVID-19 with sponta- thrombus in the aortic arch. J Thorac Cardiovasc neous pneumomediastinum. Lancet Infect Dis. 2020 Surg. 2016; 152(3): 810-817. abril; 20(4): 510. 23. Yang S, Yu J, Zeng W, Yang L, Teng L, Cui Y, et al. 8. Meireles J, Neves S, Castro A, França M. Spontaneous Aortic floating thrombus detected by computed to- pneumomediastinum revisited. Respiratory Medicine mography angiography incidentally: Five cases and CME. 2011 enero 1; 4(4): 181-183. a literature review. J Thorac Cardiovasc Surg. 2017; 9. Murayama S, Gibo S. Spontaneous pneumomediasti- 153(4): 791-803. num and Macklin effect: Overview and appearance on 24. Bo H, Li Y, Liu G, Ma Y, Li Z, Cao J, et al. Assessing computed tomography. World J Radiol. 2014 noviembre the Risk for Development of Deep Vein Thrombosis 28; 6(11): 850-854. among Chinese Patients using the 2010 Caprini Risk 10. Meng L, Qiu H, Wan L, Ai Y, Xue Z, Guo Q, et Assessment Model: A Prospective Multicenter Study. al. Intubation and Ventilation amid the COVID-19 J Atheroscler Thromb. 2019 diciembre 17; 27(8): 801- OutbreakWuhan’s Experience. Anesthesiology. 2020 808. junio 1; 132(6): 1317-1332. 25. Cook DJ, Crowther MA, Meade MO, Douketis J, VTE 11. Wang W, Gao R, Zheng Y, Jiang L. COVID-19 with in the ICU Workshop Participants. Prevalence, inci- spontaneous pneumothorax,pneumomediastinum dence, and risk factors for venous thromboembolism and subcutaneous emphysema. J Travel Med. 2020 in medical-surgical intensive care unit patients. J Crit abril 25; 27(5): taaa062. Care. 2005 diciembre; 20(4): 309-313. 12. Rohailla S, Ahmed N, Gough K. SARS-CoV-2 infection 26. Marone EM, Rinaldi LF. Upsurge of deep venous associated with spontaneous pneumothorax. CMAJ. thrombosis in patients affected by COVID-19: Preli- 2020 abril 21; 192(19): E510. minary data and possible explanations. J Vasc Surg 13. Bintcliffe O, Maskell N. Spontaneous pneumothorax. Venous Lymphat Disord. 2020 abril 17; 8(4): 694-695. BMJ (citado 21 de mayo de 2020). 2014 mayo 8; 348. 27. Smeeth L, Cook C, Thomas S, Hall AJ, Hubbard R, Disponible en: https://www.bmj.com/content/348/bmj. Vallance P. Risk of deep vein thrombosis and pulmo- g2928 nary embolism after acute infection in a community 14. Tang N, Li D, Wang X, Sun Z. Abnormal coagulation setting. Lancet. 2006 abril 1; 367(9516): 1075-1079. parameters are associated with poor prognosis in 28. Rosendaal FR. Venous thrombosis: a multicausal patients with novel coronavirus pneumonia. J Thromb disease. Lancet. 1999 abril 3; 353(9159): 1167-1173. Haemost. 2020; 18(4): 844-847. 29. Mao L, Jin H, Wang M, Hu Y, Chen S, He Q, et al. 15. Margetic S. Inflammation and haemostasis. Biochem Neurologic Manifestations of Hospitalized Patients Med (Zagreb). 2012 febrero 15; 22(1): 49-62. With Coronavirus Disease 2019 in Wuhan, China. 16. Grillet F, Behr J, Calame P, Aubry S, Delabrousse E. JAMA Neurol. 2020 abril 10; 77(6): 1-9. Acute Pulmonary Embolism Associated with COVID-19 30. Zhang Y, Xiao M, Zhang S, Xia P, Cao W, Jiang W, Pneumonia Detected by Pulmonary CT Angiography. et al. Coagulopathy and Antiphospholipid Antibodies Radiology. 2020 abril 23; 201544. in Patients with Covid-19. N Engl J Med. 23 de 2020; 17. Franco-López Á, Poveda JE, Gilabert NV. Tromboem- 382(17): e38. bolismo Pulmonar en los pacientes con COVID-19. 31. Thachil J, Tang N, Gando S, Falanga A, Cattaneo M,

160 Rev Chil Radiol 2020; 26(4) ARTÍCULO DE REVISIÓN

Levi M, et al. ISTH interim guidance on recognition and novel etiology of fulminant myocarditis. Herz. 2020; management of coagulopathy in COVID-19. J Thromb 45(3): 230-232. Haemost. 2020; 18(5): 1023-1026. 47. Buendía-Roldán I, Navarro C, Rojas-Serrano J. Diffuse 32. Avula A, Nalleballe K, Narula N, Sapozhnikov S, Dandu alveolar hemorrhage: Causes and outcomes in a referral V, Toom S, et al. COVID-19 presenting as stroke. Brain center. Reumatol Clin. 2010 agosto; 6(4): 196-198. Behav Immun. 2020 abril 28; 87: 115-119. 48. Gómez-Román JJ. Hemorragias alveolares difusas 33. Mei H, Hu Y. Characteristics, causes, diagnosis and pulmonares. Arch Bronconeumol. 2008 agosto 1; 44(8): treatment of coagulation dysfunction in patients with 428-36. COVID-19. Zhonghua Xue Ye Xue Za Zhi. 14 de 2020; 49. Cordier J-F, Cottin V. Alveolar hemorrhage in vasculitis: 41(3): 185-191. primary and secondary. Semin Respir Crit Care Med. 34. Vulliamy P, Jacob S, Davenport RA. Acute aorto-iliac 2011 junio; 32(3): 310-321. and mesenteric arterial thromboses as presenting 50. Giménez Palleiro A, Franquet T. Patrones radiológicos features of COVID-19. Br J Haematol. 2020 abril 30; en la enfermedad pulmonar intersticial. Semin Fund 189(6): 1053-1054. Esp Reumatol. 2013 octubre 1; 14(4): 97-105. 35. Lee SS, Park SH. Computed tomography evaluation of 51. Mohr LC. Hypersensitivity pneumonitis. Curr Opin Pulm gastrointestinal bleeding and acute mesenteric ische- Med. 2004 septiembre; 10(5): 401-411. mia. Radiol Clin North Am. 2013 enero; 51(1): 29-43. 52. Morell F, Roger À, Reyes L, Cruz MJ, Murio C, Muñoz X. 36. Mönkemüller K, Fry L, Rickes S. COVID-19, coronavirus, Bird Fancier’s Lung: A Series of 86 Patients. Medicine. SARS-CoV-2 and the small bowel. Rev Esp Enferm Dig. 2008 marzo; 87(2): 110-130. 2020 mayo; 112(5): 383-388. 53. Glazer CS, Rose CS, Lynch DA. Clinical and radiologic 37. Decoste R, Himmelman JG, Grantmyre J. Acute renal manifestations of hypersensitivity pneumonitis. J Thorac infarct without apparent cause: A case report and Imaging. 2002 octubre; 17(4): 261-272. review of the literature. Can Urol Assoc J. 2015 abril; 54. Miller WT, Shah RM. Isolated diffuse ground-glass opacity 9(3-4): E237-239. in thoracic CT: causes and clinical presentations. AJR Am 38. Freeman JL, Jafri SZ, Roberts JL, Mezwa DG, Shirkhoda J Roentgenol. febrero de 2005; 184(2): 613-622. A. CT of congenital and acquired abnormalities of the 55. Tian XL, Peng M, Wang HP, Cai BQ, Xu WB, Zhu YJ, et al. spleen. Radiographics. 1993 mayo; 13(3): 597-610. The differential diagnosis for novel coronavirus pneumonia 39. Landefeld CS, Beyth RJ. Anticoagulant-related bleeding: and similar lung diseases in general hospitals. Zhonghua clinical epidemiology, prediction, and prevention. Am J Jie He He Hu Xi Za Zhi. 2020 marzo 10; 43(0): E035. Med. 1993 septiembre; 95(3): 315-328. 56. Shelhamer JH, Gill VJ, Quinn TC, Crawford SW, Kovacs 40. Nazarian LN, Lev-Toaff AS, Spettell CM, Wechsler RJ. JA, Masur H, et al. The laboratory evaluation of opportu- CT assessment of abdominal hemorrhage in coagulo- nistic pulmonary infections. Ann Intern Med. 1996 marzo pathic patients: impact on clinical management. Abdom 15; 124(6): 585-599. Imaging. 1999 junio; 24(3): 246-249. 57. Mesurolle B, Qanadli SD, Merad M, Mignon F, Baldeyrou P, 41. Donaldson J, Knowles CH, Clark SK, Renfrew I, Lobo Tardivon A, et al. Unusual radiologic findings in the thorax MD. Rectus sheath haematoma associated with low after radiation therapy. Radiographics. 2000 febrero; 20(1): molecular weight heparin: a case series. Ann R Coll 67-81. Surg Engl. 2007 abril; 89(3): 309-312. 58. Martínez Pérez C, Gumbau Puchol V, Basés Valenzuela 42. Pathi R, Voyvodic F, Thompson WR. Spontaneous C, Villalba Ferrer F, Fuster Diana C. Radiation pneumo- extraperitoneal haemorrhage: computed tomography nitis after breast-conserving surgery for cancer. Cir Esp. diagnosis and treatment by selective arterial emboli- octubre 2015; 93(8): e91-93. zation. Australas Radiol. junio 2004; 48(2): 123-128. 59. Seo JB, Im J-G, Goo JM, Chung MJ, Kim M-Y. Atypical 43. Hani C, Trieu NH, Saab I, Dangeard S, Bennani S, Chas- Pulmonary Metastases: Spectrum of Radiologic Findings. sagnon G, et al. COVID-19 pneumonia: A review of typical RadioGraphics. 2001 marzo 1; 21(2): 403-4017. CT findings and differential diagnosis. Diagnostic and 60. Goldsmith HS, Bailey HD, Callahan EL, Beattie EJ. Pul- Interventional Imaging. 2020 mayo 1; 101(5): 263-268. monary lymphangitic metastases from breast carcinoma. 44. Wang Y, Dong C, Hu Y, Li C, Ren Q, Zhang X, et al. Arch Surg. 1967 abril; 94(4): 483-488. Temporal Changes of CT Findings in 90 Patients with 61. Castañer E, Gallardo X, Pallardó Y, Branera J, Cabezuelo COVID-19 Pneumonia: A Longitudinal Study. Radiology. M, Mata J. Diseases affecting the peribronchovascular 2020 marzo 19; 200843. interstitium: CT findings and pathologic correlation. Current 45. Cheng Z, Lu Y, Cao Q, Qin L, Pan Z, Yan F, et al. Clinical problems in diagnostic radiology. 2005 marzo 1; 34(2): Features and Chest CT Manifestations of Coronavirus 63-75. Disease 2019 (COVID-19) in a Single-Center Study in 62. Brown K, Mund DF, Aberle DR, Batra P, Young DA. Shanghai, China. AJR Am J Roentgenol. 2020 marzo Intrathoracic calcifications: radiographic features and 14; 1-6. differential diagnoses. Radiographics. 1994 nov; 14(6): 46. Chen C, Zhou Y, Wang DW. SARS-CoV-2: a potential 1247-1261.

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