High-resolution CT in the differential diagnosis of consolidative processes (I. Acute processes)

Consolidations are usually result of the replacement of the alveolar air by fluid, cells or tissue but these can also be seen with extensive interstitial processes. These diseases cannot be clearly categorized into the classic classification scheme of airspace and interstitial disease since there are features of both categories seen in the imaging and histologic findings. Because this definition includes wide variety of diseases with overlapping HRCT-findings it is difficult to distinguish among these entities with imaging criteria alone. However, integration of HRCT-findings and clinical findings may enable a narrower differential diagnosis. This review describes the most common types of lung diseases associated with acute appearance of consolidation and discuss the differential diagnosis.     

High-resolution CT in the differential diagnosis of consolidative lung processes. (Part 2, Chronic processes)

Consolidations are characterized on CT by the presence of one or more airspace opacities with little or no volume loss. Because HRCT findings overlap among various entities, it may be sometimes to be impossible to make a definite diagnosis with imaging criteria alone. If the symptoms are chronic (weeks to months) the differential diagnosis may include alveolar proteinosis, bronchioloalveolar carcinoma, lymphoma as well as inflammatory diseases. This review describes the most common types of lung diseases associated with chronic appearance of consolidation and discuss the differential diagnosis.     

严重急性呼吸综合征的临床与影像学表现

目的　研究SARS患者不同阶段的临床与影像学改变。方法　对 12 3例住院患者进行影像与临床分析。结果　影像改变 :早期 ,病灶多发或单发 ,表现多种多样 ,肺实质改变不明显 ;进展期 ,病变迅速发展 ,范围扩大 ,病灶数目明显增多 ,影像表现呈多样性 ;吸收期 ,病灶明显缩小、变淡 ,部分有纤维化表现。胸部CR、DR与HRCT影像学表现相似 ,但HRCT更敏感。临床表现 :早期 ,发热、全身及关节酸痛 ,咳嗽 ,白细胞正常或偏低 ;进展期 ,在上述症状加重的基础上出现血氧饱和度下降 ,有 2 0 %的患者发展为ARDS ;恢复期 ,80 %的患者好转康复出院。结论　SARS的影像表现与其它肺炎相似 ,特异性不强 ,肺部病变的变化与临床表现无明显相关性。但是影像学仍是作为治疗、了解病变的重要依据。     

Pulmonary involvement in Churg-Strauss syndrome: an analysis of CT,clinical, and pathologic findings

We tried to assess retrospectively thin-section CT findings of Churg-Strauss syndrome (CSS) in 25 patients and to compare these findings with clinical and histopathologic findings. Of 25 patients, 19 (76%) had parenchymal abnormalities at CT; small nodules (n = 12; 63%), ground-glass opacity (n = 10; 53%), bronchial wall thickening (n = 10; 53%), and consolidation (n = 8; 42%). Parenchymal abnormalities (n = 19) were categorizable as an airway pattern in 11 and an airspace pattern in eight. Patients with an airway pattern (n = 5) had obstructive (n = 3) or combined (n = 2) PFT results, whereas those with an airspace pattern (n = 4) had restrictive (n = 3) or obstructive (n = 1) results. Parenchymal opacities at CT corresponded histologically to areas of eosinophilic pneumonia, necrotizing granulomas, and granulomatous vasculitis; small nodules to eosinophilic bronchiolitis and peribronchiolar vasculitis; and bronchial wall thickening to airway wall eosinophil and lymphocyte infiltration. Patients with airspace pattern responded more readily to treatment than those with airway pattern. CT shows lung parenchymal abnormalities in about three-quarters of CSS patients and these abnormalities can be categorized as airspace or airway patterns. This classification helps predict PFT data, underlying histopathology, and treatment response.     

Diagnóstico radiológico del paciente con COVID-19

The pandemia caused by the SARS-CoV-2 virus has triggered an unprecedented health and economic crisis. Although the diagnosis of infection with SARS-CoV-2 is microbiological, imaging techniques play an important role in supporting the diagnosis, grading the severity of disease, guiding treatment, detecting complications, and evaluating the response to treatment. The lungs are the main organ involved, and chest X-rays, whether obtained in conventional X-ray suites or with portable units, are the first-line imaging test because they are widely available and economical. Chest CT is more sensitive than plain chest X-rays, and CT studies make it possible to identify complications in addition to pulmonary involvement, as well as to suggestive alternative diagnoses. The most common radiologic findings in COVID-19 are airspace opacities (consolidations and/or ground-glass opacities), which are typically bilateral, peripheral, and located primarily in the lower fields.     

Chest radiological finding of COVID-19 in patients with and without diabetes mellitus: Differences in imaging finding

The pandemic of novel coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diabetes mellitus is a risk factor for developing severe illness and a leading cause of death in patients with COVID-19. Diabetes can precipitate hyperglycaemic emergencies and cause prolonged hospital admissions. Insulin resistance is thought to cause endothelial dysfunction, alveolar capillary micro-angiopathy and interstitial lung fibrosis through pro-inflammatory pathways. Autopsy studies have also demonstrated the presence of microvascular thrombi in affected sections of lung, which may be associated with diabetes. Chest imaging using x-ray (CXR) and computed tomography (CT) of chest is used to diagnose, assess disease progression and severity in COVID-19. This article reviews current literature regarding chest imaging findings in patients with diabetes affected by COVID-19. A literature search was performed on PubMed. Patients with diabetes infected with SARS-CoV-2 are likely to have more severe infective changes on CXR and CT chest imaging. Severity of airspace consolidation on CXR is associated with higher mortality, particularly in the presence of co-morbidities such as ischaemic heart disease. Poorly controlled diabetes is associated with more severe acute lung injury on CT. However, no association has been identified between poorly-controlled diabetes and the incidence of pulmonary thromboembolism in patients with COVID-19.     

Spectrum of pulmonary aspergillosis: histologic, clinical, and radiologic findings.

Aspergillosis is a serious pathologic condition caused by Aspergillus organisms and is frequently seen in immunocompromised patients. At computed tomography (CT), saprophytic aspergillosis (aspergilloma) is characterized by a mass with soft-tissue attenuation within a lung cavity. The mass is typically separated from the cavity wall by an airspace ("air crescent" sign) and is often associated with thickening of the wall and adjacent pleura. CT findings in allergic bronchopulmonary aspergillosis consist primarily of mucoid impaction and bronchiectasis involving predominantly the segmental and subsegmental bronchi of the upper lobes. Aspergillus necrotizing bronchitis may manifest as an endobronchial mass, obstructive pneumonitis or collapse, or a hilar mass. Bronchiolitis is characterized by centrilobular nodules and branching linear or nodular areas of increased attenuation ("tree-in-bud" pattern). Obstructing bronchopulmonary aspergillosis mimics allergic bronchopulmonary aspergillosis at CT and manifests as bilateral bronchial and bronchiolar dilatation, large mucoid impactions, and diffuse lower lobe consolidation caused by postobstructive atelectasis. Characteristic CT findings in angioinvasive aspergillosis consist of nodules surrounded by a halo of ground-glass attenuation ("halo sign") or pleura-based, wedge-shaped areas of consolidation. Although imaging findings in pulmonary aspergillosis may be nonspecific, in the appropriate clinical setting, familiarity with the CT findings may suggest or even help establish the diagnosis.     

CT findings in primary pulmonary lymphomas

PURPOSE: To describe the CT findings of pathologically confirmed primary pulmonary lymphomas. MATERIALS AND METHODS: The CT examinations of 11 patients with pathologically proven primary pulmonary lymphoma (9 BALT lymphomas and 2 non-BALT lymphomas) were retrospectively reviewed by three radiologists. Evaluated findings included morphology (consolidation, mass, nodule), number and distribution of lesions. Other CT findings such as air bronchogram, lymphadenopathy, atelectasis and pleural effusion were also assessed. RESULTS: Pulmonary lesions were depicted as airspace consolidation (pneumonia-like) in 5 patients (45%), tumour-like rounded opacity in 4 (36%), and nodules in 4 (36%). Multiple and bilateral lung lesions were seen in 3 patients (27%). Air bronchogram was present in 7 patients (63%), lymphadenopathy in 3 (27%), atelectasis in 4 (36%) and pleural effusion in only 1 (9%). CONCLUSIONS: Our results agree with previous studies regarding lesion patterns and their relative frequency. A smaller number of nodules and multiple lesions were found compared with some previous studies. The most frequent pattern was airspace consolidation.     

Assessment of lung ventilation by MR imaging: current status and future perspectives

The aim of this paper is to review the present status of novel MRI techniques as a new important instrument for functional ventilation imaging. The current status and future perspectives in research and clinical applications are summarized. Morphological lung imaging is based on chest radiography and computed tomography, whereas scintigraphy is used for ventilation imaging. During recent years, MRI has emerged as a new means for functional imaging of ventilation. Aerosolized contrast agents and oxygen are used in proton imaging, whereas non-proton imaging relies on fluorine compounds, such as sulfur hexafluoride and perfluorcarbons, or on hyperpolarized noble gases, such as helium-3 or xenon-129. All the gases are administered as inhaled "contrast agents" for imaging of the airways and airspaces. In general, straightforward images demonstrate the homogeneity of ventilation in a breath-hold and allow for determination of ventilated lung. The different properties of the different compounds enable the measurement of additional functional parameters. They comprise airspace size, regional oxygen partial pressure, and analysis of ventilation distribution, ventilation/perfusion ratios, and gas exchange, including oxygen uptake. Novel MRI techniques provide the potential for functional imaging of ventilation. The next steps include definition of the value and the potential of the different contrast mechanisms as well as determination of the significance of the functional information with regard to physiological research and patient management in chronic obstructive pulmonary disease and others.     

Paracoccidioidomycosis: High-resolution computed tomography-pathologic correlation

Objective

The purpose of this study was to describe the high-resolution computed tomography (HRCT) features of pulmonary paracoccidioidomycosis and to correlate them with pathologic findings.

Methods

The study included 23 adult patients with pulmonary paracoccidioidomycosis. All patients had undergone HRCT, and the images were retrospectively analyzed by two chest radiologists, who reached decisions by consensus. An experienced lung pathologist reviewed all pathological specimens. The HRCT findings were correlated with histopathologic data.

Results

The predominant HRCT findings included areas of ground-glass opacities, nodules, interlobular septal thickening, airspace consolidation, cavitation, and fibrosis. The main pathological features consisted of alveolar and interlobular septal inflammatory infiltration, granulomas, alveolar exudate, cavitation secondary to necrosis, and fibrosis.

Conclusion

Paracoccidioidomycosis can present different tomography patterns, which can involve both the interstitium and the airspace. These abnormalities can be pathologically correlated with inflammatory infiltration, granulomatous reaction, and fibrosis.     

AIDS与非AIDS患者肺毛霉菌病影像表现对比分析

目的:探讨AIDS与非AIDS患者肺毛霉菌病影像表现特点。方法:回顾性分析33例肺毛霉菌病患者(AIDS组24例,非AIDS组9例)胸部X线及CT(常规CT扫描和薄层CT扫描)影像表现。结果:肺毛霉菌病的常见征象有肺纹理增粗、肺内斑片状渗出性病灶、双肺多发粟粒样结节影、磨玻璃样密度影、肺气囊、肺门和纵隔淋巴结肿大、胸腔积液等。其中非AIDS组肺内多发渗出性病灶的发生率(9例,100%)高于AIDS组(14例,58.3%),两组差异有统计学意义(P=0.032);双肺多发粟粒样结节影则更多见于AIDS组(9例,37.5%),非AIDS组未见此征象(0例),两组差异有统计学意义(P=0.039)。结论:肺毛霉菌病的影像表现多种多样;肺毛霉菌病在非AIDS组中以肺部渗出性改变最为常见,在AIDS组中则以双肺多发粟粒样结节影为特点。     

Herpes simplex virus 1 pneumonia: conventional chest radiograph pattern

The aim of this study was to describe the findings on plain chest radiographs in patients with herpes simplex virus pneumonia (HSVP). The study was based on 17 patients who at a retrospective search have been found to have a monoinfection with herpes simplex virus. The diagnosis was established by isolation of the virus from material obtained during fiberoptic bronchoscopy (FOB) which also included broncho-alveolar lavage and tissue sampling. Fourteen patients had a chest radiograph performed within 24 h of the date of the FOB. Two radiographs showed no abnormalities of the lung parenchyma. The radiographs of the other 12 patients showed lung opacification, predominantly lobar or more extensive and always bilateral. Most patients presented with a mixed airspace and interstitial pattern of opacities, but 11 of 14 showed at least an airspace consolidation. Lobar, segmental, or subsegmental atelectasis was present in 7 patients, and unilateral or bilateral pleural effusion in 8 patients, but only in 1 patient was it a large amount. In contradiction to the literature which reports a high correlation between HSVP and acute respiratory distress syndrome (ARDS), 11 of 14 patients did not meet the pathophysiological criteria for ARDS. The radiologist may suggest the diagnosis of HSVP when bilateral airspace consolidation or mixed opacities appear in a susceptible group of patients who are not thought to have ARDS or pulmonary edema. The definite diagnosis of HSV pneumonia can be established only on the basis of culture of material obtained by broncho-alveolar lavage.     

Operating characteristics of hyperpolarized 3He and arterial spin tagging in MR imaging of ventilation and perfusion in healthy subjects

RATIONALE AND OBJECTIVES: The authors tested the feasibility of a magnetic resonance (MR) imaging method combining the use of hyperpolarized helium 3 (3He) for ventilation imaging and an arterial spin-tagging sequence for perfusion imaging in six healthy human subjects. MATERIALS AND METHODS: High-resolution sagittal images depicting 3He distribution were acquired after the subjects' inhalation of 500 mL of laser-hyperpolarized 3He produced by spin-exchange optical pumping. Perfusion MR imaging was performed with a steady-state arterial spin-tagging sequence that enabled the acquisition of three-dimensional images of pulmonary perfusion without the need for subject breath holding. RESULTS: The 3He ventilation images display, with high signal intensity and detailed anatomic localization, the airspace of the lung parenchyma. The signal intensity on the perfusion images decreased by 23.2% with the use of arterial spin tagging. Ventilation and perfusion were matched, as is expected in healthy subjects. CONCLUSION: This method may have important applications in the assessment of lung function, enabling the calculation of regional ventilation-perfusion ratios. It may also aid in the selection of candidates for lung volume-reduction surgery.     

Humane metapneumovirus (HMPV) associated pulmonary infections in immunocompromised adults—Initial CT findings,disease course and comparison to respiratory-syncytial-virus (RSV) induced pulmonary infections

Aim

To describe computed tomography (CT)-imaging findings in human metapneumovirus (HMPV)-related pulmonary infection as well as their temporal course and to analyze resemblances/differences to pulmonary infection induced by the closely related respiratory-syncytial-virus (RSV) in immunocompromised patients.

Materials and methods

Chest-CT-scans of 10 HMPV PCR-positive patients experiencing pulmonary symptoms were evaluated retrospectively with respect to imaging findings and their distribution and results were then compared with data acquired in 13 patients with RSV pulmonary infection. Subsequently, we analyzed the course of chest-findings in HMPV patients.

Results

In HMPV, 8/10 patients showed asymmetric pulmonary findings, whereas 13/13 patients with RSV-pneumonia presented more symmetrical bilateral pulmonary infiltrates. Image analysis yielded in HMPV patients following results: ground-glass-opacity (GGO) (n = 6), parenchymal airspace consolidations (n = 5), ill-defined nodular-like centrilobular opacities (n = 9), bronchial wall thickening (n = 8). In comparison, results in RSV patients were: GGO (n = 10), parenchymal airspace consolidations (n = 9), ill-defined nodular-like centrilobular opacities (n = 10), bronchial wall thickening (n = 4). In the course of the disease, signs of acute HMPV interstitial pneumonia regressed transforming temporarily in part into findings compatible with bronchitis/bronchiolitis.

Conclusions

Early chest-CT findings in patients with HMPV-related pulmonary symptoms are compatible with asymmetric acute interstitial pneumonia accompanied by signs of bronchitis; the former transforming with time into bronchitis and bronchiolitis before they resolve. On the contrary, RSV-induced pulmonary infection exhibits mainly symmetric acute interstitial pneumonia.     

Neue Entwicklungen in der MRT des Thorax

MRI was not used often for lung imaging due to technical and physical limitations. Recent developments have considerably improved anatomical MR imaging, and at the same time new perspectives for functional imaging emerged. They consist of functional investigations of pulmonary perfusion (contrast agents, MR angiography) and ventilation (inhaled contrast aerosols, oxygen, hyperpolarized noble gases [He-3, Xe-129] and fluorinated gases [SF6]). New parameters can be measured: homogeneity of ventilation, lung volumes, airspace size, intrapulmonary oxygen partial pressure, dynamic ventilation distribution and ventilation/perfusion ratios. MRI-inherent advantages are: lack of radiation, high spatial and temporal resolution, and a broad range of functional information. MRI of lung ventilation seems to be more sensitive in the detection of ventilation defects than scintigraphy, CT or pulmonary function tests. By combining the new strategies the radiologist will be capable to improve specificity of the investigations and to characterize lung function impairments. The joint assessment of ventilation and perfusion will play a major role in this development.     

BALTOMA--long-term follow-up

PURPOSE: The purpose of this work was to describe the findings and the long term follow up of pathologically confirmed bronchus-associated lymphoid tissue lymphoma (BALTOMA) in 6 patients. METHODS: CT examinations and conventional radiological examinations were reviewed and compared to describe typical radiological findings and patterns of pulmonary manifestations. It were described the number of lesions and characteristics like presence of airspace consolidation, ground-glass attenuation, bubble-like radiolucencies, air bronchogram, bronchial dilatation, Infiltration and the long term behaviour of the manifestations. RESULTS: Lesions with a positive air bronchogram, no infiltration of extrapulmonary tissue or extrapulmonary manifestations were revealed as typical findings. Only a slow or no progression of disease was shown in most patients over a term of up to twelve years. CONCLUSIONS: The lymphoma of the bronchus-associated lymphoid tissue of the lung is a rare tumor. A positive air bronchogram, a multiplicity of disease, bilateral lesions, a fibrotic transformation of the lung tissue and no growth or only a slow groth over al long term of observation are typical radiological findings.     

Accuracy of low-dose computed tomography (CT) for detecting and characterizing the most common CT-patterns of pulmonary disease

Purpose

To assess the ability of low-dose CT to detect and characterize the most common CT patterns of pulmonary disease.

Methods and materials

Sixty patients with nodules, consolidations or interstitial disease were scanned using a low-dose (128 mm × 0.6 mm, 40 reference mAs, 120 kVp) and standard-dose CT protocol (150 reference mAs, 120 kVp). Two radiologists with 3 and 10 years of thoracic imaging experience searched both exams in consensus for the most commonly observed CT patterns according to the Fleischner Society criteria, which consisted of 46 different subgroups of ground-glass opacities, nodules, interstitial and airspace diseases. The standard of reference was established by consensus of a panel of two experienced chest radiologists (9 and 12 years of experience).

Results

The lung segments (1080) showed 813 nodules, 596 ground-glass opacities, 74 airspace and 575 interstitial diseases and 64 normal segments. In particular, air-space disease and nodules were unaffected by the increase in noise. However, the sensitivity to detect ground-glass opacities, ground-glass nodules and interstitial opacities decreased significantly, from 89% to 77%, 86% to 68% and 91% to 71%, respectively (all p-values < 0.00001). Using iterative reconstruction instead of the applied filtered back projection sensitivity for ground-glass nodules rose to the sensitivity of standard-dose CT in an additional phantom study.

Conclusion

A low-dose CT of 40 mAs/120 kVp is feasible for detecting solid nodules, airspace, airways and pleural disease. For diagnosing pathologies consisting of ground-glass opacities or interstitial opacities, higher tube current or iterative reconstruction is required.     

Smoking-related lung abnormalities on computed tomography images: comparison with pathological findings

Smoking-related lung abnormalities are now an increasing public health concern. According to the findings of large-cohort studies, approximately 8% of smokers have interstitial lung abnormalities, which are associated with a relatively high risk of all-cause mortality. We reviewed the radiological and pathological findings of smoking-related interstitial lung diseases, such as respiratory bronchiolitis-interstitial lung disease, desquamative interstitial pneumonia, and airspace enlargement with fibrosis. We have also discussed the histological basis of unclassifiable interstitial pneumonia in smokers, which exhibits airway-centered cystic lesions with fibrosis. A variety of radiological findings coexist in the lungs of a smoker. This overlapping of multiple pathological conditions might cause the radiological patterns of diseases to become unclassifiable. Therefore, diagnosis should be performed not on the basis of a single radiological finding, but in a comprehensive manner, by including clinical symptoms and disease behavior. Among interstitial abnormalities in smokers, the usual interstitial pneumonia (UIP) pattern is correlated with a worse prognosis than others. Basal-predominant subpleural reticulation is a clue for accurate diagnosis of UIP, which can be achieved by computer-aided quantitative analysis.     

High resolution CT findings in miliary lung disease.

High-resolution CT (HRCT) and chest radiographs were compared in nine patients with miliary lung disease. In all cases, miliary disease was documented to be infectious in etiology; six of these patients proved to be human immunodeficiency virus (HIV) positive. A mixture of both sharply and poorly defined 1-3 mm nodules was seen in all cases, many of the latter having an appearance indistinguishable from airspace nodules. Other features attributable to the presence of nodules included nodular interlobular septae, nodular irregularity of vessels, subpleural dots, and studded fissures. Diffuse intra- and interlobular septal thickening also proved common, seen in all but one case (91%). Based on limited HRCT-pathologic correlation, CT findings appear primarily to be due to granulomatous foci developing in a seemingly random distribution involving both pulmonary airspaces as well as the interstitium. It is concluded that in the appropriate clinical setting this constellation of findings is characteristic of miliary disease; the role of HRCT especially in the early diagnosis of miliary disease in HIV positive patients remains to be determined prospectively.