Computed tomography halo sign in pulmonary nodules: frequency and diagnostic value

Imaging of Pulmonary Sarcoidosis-A Review

Sarcoidosis is the classic multisystem granulomatous disease. First reported as a disorder of the skin, it is now clear that, in the overwhelming majority of patients with sarcoidosis, the lungs will bear the brunt of the disease. This review explores some of the key concepts in the imaging of pulmonary sarcoidosis: the wide array of typical (and some of the less common) findings on high-resolution computed tomography (HRCT) are reviewed and, with this, the concept of morphologic/HRCT phenotypes is discussed. The pathophysiologic insights provided by HRCT through studies where morphologic abnormalities and pulmonary function tests are compared are evaluated. Finally, this review outlines the important contribution of HRCT to disease monitoring and prognostication.

Guidance on Imaging for Invasive Pulmonary Aspergillosis and Mucormycosis: From the Imaging Working Group for the Revision and Update of the Consensus Definitions of Fungal Disease from the EORTC/MSGERC

BACKGROUND

Clinical imaging in suspected invasive fungal disease (IFD) has a significant role in early detection of disease and helps direct further testing and treatment. Revised definitions of IFD from the EORTC/MSGERC were recently published and provide clarity on the role of imaging for the definition of IFD. Here, we provide evidence to support these revised diagnostic guidelines.

METHODS

We reviewed data on imaging modalities and techniques used to characterize IFDs.

RESULTS

Volumetric high-resolution computed tomography (CT) is the method of choice for lung imaging. Although no CT radiologic pattern is pathognomonic of IFD, the halo sign, in the appropriate clinical setting, is highly suggestive of invasive pulmonary aspergillosis (IPA) and associated with specific stages of the disease. The ACS is not specific for IFD and occurs in the later stages of infection. By contrast, the reversed halo sign and the hypodense sign are typical of pulmonary mucormycosis but occur less frequently. In noncancer populations, both invasive pulmonary aspergillosis and mucormycosis are associated with "atypical" nonnodular presentations, including consolidation and ground-glass opacities.

CONCLUSIONS

A uniform definition of IFD could improve the quality of clinical studies and aid in differentiating IFD from other pathology in clinical practice. Radiologic assessment of the lung is an important component of the diagnostic work-up and management of IFD. Periodic review of imaging studies that characterize findings in patients with IFD will inform future diagnostic guidelines.

Chest complications in immunocompromised patients without acquired immunodeficiency syndrome (AIDS): differentiation between infectious and non-infectious diseases using high-resolution CT findings

AIM

To differentiate between infectious and non-infectious diseases occurring in immunocompromised patients without acquired immunodeficiency syndrome (AIDS) using high-resolution computed tomography (HRCT).

MATERIALS AND METHODS

HRCT images of 555 patients with chest complications were reviewed retrospectively. Infectious diseases (n=341) included bacterial pneumonia (n=123), fungal infection (n=80), septic emboli (n=11), tuberculosis (n=15), pneumocystis pneumonia (n=101), and cytomegalovirus pneumonia (n=11), while non-infectious diseases (n=214) included drug toxicity (n=84), infiltration of underlying diseases (n=83), idiopathic pneumonia syndrome (n=34), diffuse alveolar haemorrhage (n=8), and pulmonary oedema (n=5). Lung parenchymal abnormalities were compared between the two groups using the χ² test and multiple logistic regression analysis.

RESULTS

The χ2 test results showed significant differences in many HRCT findings between the two groups. Multiple logistic regression analysis results indicated the presence of nodules with a halo and the absence of interlobular septal (ILS) thickening were the significant indicators that could differentiate infectious from non-infectious diseases. ILS thickening was generally less frequent among most infectious diseases and more frequent among most non-infectious diseases, with a good odds ratio (7.887, p<0.001). The sensitivity and accuracy for infectious diseases in the absence of ILS thickening were better (70% and 73%, respectively) than those of nodules with a halo (19% and 48%, respectively), while the specificity in the nodules with a halo was better (93%) than that of ILS thickening (78%).

CONCLUSIONS

The presence of nodules with a halo or the absence of ILS thickening tends to suggest infectious disease. Specifically, ILS thickening seems to be a more reliable indicator.

The halo sign: HRCT findings in 85 patients

Objective:

The halo sign consists of an area of ground-glass opacity surrounding pulmonary lesions on chest CT scans. We compared immunocompetent and immunosuppressed patients in terms of halo sign features and sought to identify those of greatest diagnostic value.

Methods:

This was a retrospective study of CT scans performed at any of seven centers between January of 2011 and May of 2015. Patients were classified according to their immune status. Two thoracic radiologists reviewed the scans in order to determine the number of lesions, as well as their distribution, size, and contour, together with halo thickness and any other associated findings.

Results:

Of the 85 patients evaluated, 53 were immunocompetent and 32 were immunosuppressed. Of the 53 immunocompetent patients, 34 (64%) were diagnosed with primary neoplasm. Of the 32 immunosuppressed patients, 25 (78%) were diagnosed with aspergillosis. Multiple and randomly distributed lesions were more common in the immunosuppressed patients than in the immunocompetent patients (p < 0.001 for both). Halo thickness was found to be greater in the immunosuppressed patients (p < 0.05).

Conclusions:

Etiologies of the halo sign differ markedly between immunocompetent and immunosuppressed patients. Although thicker halos are more likely to occur in patients with infectious diseases, the number and distribution of lesions should also be taken into account when evaluating patients presenting with the halo sign.

Clinical manifestations and outcomes of pulmonary aspergillosis: experience from Pakistan

Introduction

Pulmonary aspergillosis has variable course of illness, severity and outcomes depending on underlying conditions. There is limited data available on the clinical manifestations and outcome of pulmonary aspergillosis from Pakistan.

Methods

To determine the clinical manifestations and outcome of pulmonary aspergillosis in a tertiary care hospital a retrospective study was conducted from 2004 to 2014 in patients admitted with pulmonary aspergillosis at the Aga Khan University Hospital Karachi, Pakistan.

Results

Of the 280 cases with provisional diagnosis of aspergillosis 69 met the inclusion criteria. The mean age was 45±15.7 years, 48 (69.6%) were men and 21 (30.4%) had diabetes mellitus (DM). The average length of hospital stay (LOS) was 10.61±9.08 days. Aspergillus fumigatus was the most common (42.0%), followed by Aspergillus flavus (28.9%). More than one-third of patients previously had tuberculosis (TB) (39.13%). The commonest pulmonary manifestation was chronic pulmonary aspergillosis (CPA) 47 (68.1%) followed by invasive pulmonary aspergillosis (IPA) 12 (17.4%) and subacute invasive aspergillosis (SAIA) 8 (11.6%). Surgical excision was performed in 28 patients (40.57%). Intensive care unit admission was required for 18 patients (26.08%). Case fatality rate was 14/69 (20.3%). DM, mean LOS and hypoxic respiratory failure were identified as independent risk factors of mortality on multivariate analysis.

Conclusion

A. fumigatus was the most frequent species found especially in patients with prior TB. CPA was the commonest pulmonary manifestation seen as post TB sequel. Diabetes, hypoxic respiratory failure and increased LOS were independent predictors of poor outcomes. Overall patients had good outcome with CPA compared with SAIA and IPA.

A Case of Rapid Exacerbation of Pulmonary Mycobacterium Avium Complex Infection Mimicking Pulmonary Aspergillosis

We herein report a case of pulmonary Mycobacterium avium complex (MAC) infection with pulmonary multiple nodules and the "halo sign" on chest computed tomography (CT) in which the patient showed rapid exacerbation seven years after undergoing bone marrow transplantation (BMT). A 68-year-old Japanese female visited our hospital due to a productive cough and dyspnea. She had undergone allogeneic BMT for acute myelocytic leukemia and received both prednisolone (2 mg/day) and cyclosporine (30 mg/day). Chest CT demonstrated no abnormal findings on admission; however, multiple pulmonary nodules and the "halo sign" were detected three weeks later. Although a fungal infection was initially suspected, a bronchoscopic examination revealed pulmonary MAC infection. In the present case, pulmonary MAC infection exhibited rapid progression with unique CT findings. Physicians should consider MAC infection in the differential diagnosis in patients who receive BMT and/or immunosuppressive agents, even if the clinical and radiological findings are atypical of the disease.

Septic pulmonary embolism caused by a Klebsiella pneumoniae liver abscess: clinical characteristics, imaging findings, and clinical courses

OBJECTIVES

Septic pulmonary embolism caused by a Klebsiella (K.) pneumoniae liver abscess is rare but can cause considerable morbidity and mortality. However, clinical information regarding this condition is limited. This study was conducted to elucidate the full disease spectrum to improve its diagnosis and treatment.

METHOD

We reviewed the clinical characteristics, imaging findings, and clinical courses of 14 patients diagnosed with septic pulmonary embolism caused by a K. pneumoniae liver abscess over a period of 9 years.

RESULTS

The two most prevalent symptoms were fever and shortness of breath. Computed tomography findings included a feeding vessel sign (79%), nodules with or without cavities (79%), pleural effusions (71%), peripheral wedge-shaped opacities (64%), patchy ground-glass opacities (50%), air bronchograms within a nodule (36%), consolidations (21%), halo signs (14%), and lung abscesses (14%). Nine (64%) of the patients developed severe complications and required intensive care. According to follow-up chest radiography, the infiltrates and consolidations were resolved within two weeks, and the nodular opacities were resolved within one month. Two (14%) patients died of septic shock; one patient had metastatic meningitis, and the other had metastatic pericarditis.

CONCLUSION

The clinical presentations ranged from insidious illness with fever and respiratory symptoms to respiratory failure and septic shock. A broad spectrum of imaging findings, ranging from nodules to multiple consolidations, was detected. Septic pulmonary embolism caused by a K. pneumoniae liver abscess combined with the metastatic infection of other vital organs confers a poor prognosis.

Pulmonary cryptococcosis: comparison of CT findings in immunocompetent and immunocompromised patients

BACKGROUND

Computed tomography (CT) findings in patients with pulmonary cryptococcosis have been reported, however, many reports were limited by the small number of patients, and not taken into account the distinction between immunocompetent and immunocompromised patients.

PURPOSE

To retrospectively evaluate thoracic CT findings in patients with pulmonary cryptococcosis whose immune status ranged from normal to severely compromised, and determine characteristic imaging features of pulmonary cryptococcosis between patients with different immune status.

MATERIAL AND METHODS

CT scan findings of 29 immunocompetent and 43 immunocompromised patients with clinically proven pulmonary cryptococcosis were reviewed retrospectively. Different patterns of CT scan abnormalities between immunocompromised and immunocompetent patients, AIDS and non-AIDS immunocompromised patients were compared by Fisher's exact test.

RESULTS

Pulmonary nodules/masses, either solitary or multiple, were the most common CT finding, present in 65 (90.3%) of the 72 patients; associated findings included CT halo sign (n = 24), cavitation (n = 23), and air bronchogram (n = 17). Areas of consolidation (n = 14), areas of GGO (n = 13), linear opacities (n = 11), lymphadenopathy (n = 5), and pleural effusion (n = 8) were uncommon. The parenchymal abnormalities were peripherally located in 47 (65.2%) of the cases. Cavitations within nodules/masses were more frequently present in immunocompromised patients than in immunocompetent patients (P = 0.009), and in AIDS patients than in non-AIDS immunocompromised patients (P = 0.002). Air bronchograms within nodules/masses were more frequent present in immunocompetent patients than in immunocompromised patients (P = 0.005). Nodules/masses with halo sign were less frequent in AIDS patients than those in non-AIDS immunocompromised patients (P = 0.027).

CONCLUSION

Pulmonary cryptococcosis should be considered in the differential diagnosis of solitary or multiple pulmonary nodules. Cavitations within nodules/masses were more commonly seen in immunocompromised patients, especially AIDS patients, while air bronchograms were more commonly seen in immunocompetent patients.

Simple pulmonary eosinophilia found on follow-up computed tomography of oncologic patients

OBJECTIVES

To investigate the prevalence of simple pulmonary eosinophilia (SPE) and validate CT findings of SPE found on follow-up CT of oncologic patients.

METHODS

We retrospectively reviewed 6977 cases of oncologic patients who underwent chest CT. A total of 66 individuals who met criteria for having SPE were identified. CT scans were fully re-assessed by consensus of 2 radiologists in terms of characteristics of pulmonary lesions.

RESULTS

The prevalence of SPE was 0.95%. A total of 193 lesions were identified and most of the lesions showed part-solid pattern (69.9%), round to ovoid contour (46.1%), ill-defined margin (90.2%), or partial halo appearance (74.8%). In addition, almost half of the lesions showed the vascular contact (49%). SPE appeared as either solitary (42.4%) or multiple lesions (57.6%). The majority of lesions were located in the periphery (76.2%), and lower lung zonal (67.4%) predominance was found.

CONCLUSIONS

The frequency of SPE in oncologic patients with CT findings of GGO, part-solid lesion was high (17.5%). Therefore, when key features of CT findings suggesting SPE (part-solid nodule; ill-defined margin; peripheral distribution; and lower lung zone predominance) are newly discovered on follow-up chest CT in oncologic patients, it would be useful to correlate with blood test and do short-term follow-up in order to avoid unnecessary invasive procedure.

Radiographic patterns in the diagnostic approach to organizing pneumonia

A 56-year-old woman, non-smoker, who complained of dry cough and dyspnea during the last month came to the emergency department due to increased dyspnea. The chest X-ray showed areas of poorly defined, bilateral alveolar opacities, leading to the diagnosis of bronchopneumonia with partial respiratory failure. During admission, she experienced an exacerbation of the dyspnea. A high-resolution computed tomography scan was performed, showing areas of ground glass opacities with interlobular septal thickening ("crazy-paving" pattern), predominantly in lower lobes. She required mechanical ventilation and she was admitted to the intensive care unit. Subsequently, an open lung biopsy was performed. The following questions should be proposed:

Nodule characterization: subsolid nodules

In this review, we focus on the radiologic, clinical, and pathologic aspects primarily of solitary subsolid pulmonary nodules. Particular emphasis will be placed on the pathologic classification and correlative computed tomography (CT) features of adenocarcinoma of the lung. The capabilities of fluorodeoxyglucose positron emission tomography-CT and histologic sampling techniques, including CT-guided biopsy, endoscopic-guided biopsy, and surgical resection, are discussed. Finally, recently proposed management guidelines by the Fleischner Society and the American College of Chest Physicians are reviewed.

Primary pulmonary cryptococcosis: evaluation of CT characteristics in 26 immunocompetent Chinese patients

BACKGROUND

Discrepancies still exist in the diagnosis of primary pulmonary cryptococcosis in immunocompetent patients.

PURPOSE

To describe and evaluate radiological manifestations of pulmonary cryptococcosis in immunocompetent patients.

MATERIAL AND METHODS

Twenty-six histopathologically confirmed cases of pulmonary cryptococcosis were analyzed for clinical, pathological, and CT characteristics. Necessary statistical tests for differences in CT presentations and correlation analysis between clinical and CT characteristics were performed.

RESULTS

The patients' ages ranged from 24 to 79 years, with 20 men and six women. Eighteen patients were symptomatic, with cough as the most common symptom (n = 14, 53.8%). Nodules (n = 21, 80.8%) were the most common CT findings. Eight cases presented with solitary and nine with multiple nodules, while 13 cases presented with irregular and 19 with ill-defined nodules. The halo sign was demonstrated, encompassing nodules in 14 of the 21 patients. Lesions were mainly localized in the lower lobes of the lungs (n = 15, 57.7%) with peripheral distribution (n = 18, 69.2%). Ground-glass opacities (GGOs) were more easily detected in older patients (66.7%, P <0.01). No significant differences in CT abnormalities were found between male and female patients.

CONCLUSION

Primary pulmonary cryptococcosis in immunocompetent patients exhibits certain CT characteristics. The typical presentation includes multiple nodules with the halo sign scattered in the peripheral field in the lower lobes of the bilateral lungs. This could contribute to diagnosis of the disease entity. However, vigilance should be exercised when facing GGOs, with or without nodules, in older patients.

An animal experiment about early pulmonary candidiasis in immunosuppressive rabbits: thin-section CT images dynamically observed and proved by histopathological results

BACKGROUND

Early detection and treatment of pulmonary fungal infection in immunocompromised patients has a profound impact on mortality. However, information available about the thin-section computed tomography (CT) findings of Candida pneumonia has largely been limited to isolated cases seen in reviews of various infections and to other acute lung diseases seen in immunocompromised patients.

PURPOSE

To dynamically observe and evaluate CT findings in immunosuppressed animals with histopathologically confirmed pulmonary candidiasis at the acute stage.

MATERIAL AND METHODS

Twenty-four New Zealand rabbits were randomly divided into an experimental group (n = 21) and a control group (n = 3). Pulmonary candidiasis was established by C. albicans inoculation via a transtracheal route in immunosuppressed rabbits in the experimental group, and an equivalent amount of normal saline was injected via the same way in the control group. Chest CT scan was performed before and on alternative days after inoculation/injection. Microbiological and pathological results were obtained by autopsy.

RESULTS

In the experiment group, pulmonary candidiasis was successfully established in 13 rabbits as confirmed by microbiology and pathology. Areas of air-space consolidation were present in 10 (10/13) rabbits, with lobular distribution in six and lobar or segmental distribution in four, pathologically presenting as bronchopneumonia or hemorrhagic lung infarcts. Areas of ground-glass opacity (GGO) were identified in five (5/13) rabbits, three of which were associated with other abnormalities, presenting as bronchopneumonia or interstitial pneumonitis. Multiple nodules were seen in three (3/13) rabbits. They were clustered around bronchovascular bundles in two rabbits, and subpleural in the remaining one, pathologically presenting as hemorrhagic granulomas. Other less common CT findings included thickening of bronchovascular bundles (n = 3), linear opacity (n = 1), and pneumothorax (n = 1). No abnormality was detected by CT scan and pathological examination in the three rabbits of the control group.

CONCLUSION

Peripheral multiple areas of lobular consolidation and/or GGO representing bronchopneumonia were the most common thin-section CT findings of pulmonary candidiasis at the early stage.

The diagnostic value of halo and reversed halo signs for invasive mold infections in compromised hosts

The halo sign is a CT finding of ground-glass opacity surrounding a pulmonary nodule or mass. The reversed halo sign is a focal rounded area of ground-glass opacity surrounded by a crescent or complete ring of consolidation. In severely immunocompromised patients, these signs are highly suggestive of early infection by an angioinvasive fungus. The halo sign and reversed halo sign are most commonly associated with invasive pulmonary aspergillosis and pulmonary mucormycosis, respectively. Many other infections and noninfectious conditions, such as neoplastic and inflammatory processes, may also manifest with pulmonary nodules associated with either sign. Although nonspecific, both signs can be useful for preemptive initiation of antifungal therapy in the appropriate clinical setting. This review aims to evaluate the diagnostic value of the halo sign and reversed halo sign in immunocompromised hosts and describes the wide spectrum of diseases associated with them.

Illustrated Brazilian consensus of terms and fundamental patterns in chest CT scans

The objective of this new Brazilian consensus is to update and to continue the standardization of the principal terms and fundamental patterns in chest CT scans in Portuguese. There is a succinct definition of the principal terms used to describe chest CT findings, as well as illustrations of classic examples. The group of authors comprised radiologists specializing in chest radiology and holding membership in the Brazilian College of Radiology and Diagnostic Imaging, as well as pulmonologists having a special interest in diagnostic imaging and holding membership in the Brazilian Thoracic Association.

Outbreak of invasive pulmonary aspergillosis among patients hospitalized in a bone marrow transplant ward: tomographic findings

OBJECTIVE

To evaluate the main aspects on CT scans of six patients hospitalized in a bone marrow transplant ward, diagnosed with invasive pulmonary aspergillosis (IPA), during an in-hospital outbreak of the disease.

METHODS

We reviewed 10 chest CT scans of six neutropenic or immunocompromised patients hospitalized in the hematology and bone marrow transplant ward of the Hospital São Paulo, in the city of São Paulo, Brazil, who were diagnosed with IPA between April of 2007 and October of 2007. The diagnosis of IPA was confirmed by anatomopathological findings (in 2 cases), culture (in 3 cases) or appropriate treatment response (in 1 case).

RESULTS

We evaluated the CT scans of three male and three female patients, ranging from 22 to 58 years of age. The most common tomographic findings were nodules (5/6 cases) and areas of consolidation (2/6 cases). The nodules were more often multiple (3/5 cases), with irregular contours (4/5 cases) and accompanied by the halo sign (3/5 cases). One case presented multiple, centrally distributed areas of consolidation, and another presented an isolated, peripheral area of consolidation. Areas of ground-glass attenuation and septal thickening were found in three and two patients, respectively. Bilateral pleural effusion occurred in three cases.

CONCLUSIONS

Consolidation, nodules, septal thickening, pleural effusion and ground-glass opacities were the principal tomographic findings in the six patients hospitalized in the above mentioned ward during the IPA outbreak. The nodules were often (in 67% of the cases) accompanied by the halo sign, a classically described finding in patients with IPA.

CAD (computed-aided detection) and CADx (computer aided diagnosis) systems in identifying and characterising lung nodules on chest CT: overview of research, developments and new prospects

Computer-aided detection (CAD) systems allow the automatic identification of lung nodules on chest computed tomography (CT), providing a second opinion to the radiologist's judgement and a volumetric evaluation of lesions - a very important aspect in oncological patients. The natural evolution of these systems has led to the introduction of computer-aided diagnosis (CADx) systems, which are able not only to identify nodules but also to characterise them by determining a likelihood of malignancy or benignity. The aim of this article is to describe the main technical principles of CAD and CADx systems, their applicability and influence in clinical practice and new prospects for their future development.

Invasive pulmonary aspergillosis in patients with COPD: a report of five cases and systematic review of the literature

BACKGROUND

There are increasing reports describing invasive pulmonary aspergillosis (IPA) in patients with chronic obstructive pulmonary disease (COPD) without the classic risk factors for this severe infection. The available literature on this association is based on case reports or small case series. The aim of this review is to systematically review these cases and describe the clinical features, diagnostic studies and outcome.

METHODS

We identified all the cases of IPA and COPD reported in the literature and had enough clinical information. We also included five cases of IPA in patients with COPD identified by the authors. These cases were systematically reviewed for clinical features, diagnostic studies and outcome.

RESULTS

There were 60 cases of IPA in patients with COPD identified from the literature. The total number of cases reviewed was 65. The mean age was 65.1 years, the mean FEV1 was 39% of predicted (n = 17, range 19-56%). Forty-nine patients were documented to be on systemic corticosteroids. The mean dose was 24 mg/day (range 15-65 mg/day). Five patients were only on inhaled corticosteroids and in 11 patients there was no documentation of corticosteroid therapy. The clinical and radiological findings were nonspecific. Thirteen patients had documented evidence of disseminated IPA. Sputum examination was positive for Aspergillus in 76% and bronchoscopy with bronchoalveolar lavage that was positive in 70%. The diagnosis of IPA was definite in 43 patients and probable in 22 patients. Forty-six patients were treated with anti-fungal therapy. Fifty-nine patients (91%) died with IPA.

CONCLUSION

Invasive pulmonary aspergillosis is an emerging serious infection in patients with COPD. The majority of these patients have advanced COPD and/or on corticosteroid therapy. The clinical and radiological presentation is nonspecific. High index of suspicion is necessary for the timely treatment of these patients.

Evaluation of patients with pulmonary nodules: when is it lung cancer?: ACCP evidence-based clinical practice guidelines (2nd edition)

BACKGROUND

Pulmonary nodules are spherical radiographic opacities that measure up to 30 mm in diameter. Nodules are extremely common in clinical practice and challenging to manage, especially small, "subcentimeter" nodules. Identification of malignant nodules is important because they represent a potentially curable form of lung cancer.

METHODS

We developed evidence-based clinical practice guidelines based on a systematic literature review and discussion with a large, multidisciplinary group of clinical experts and other stakeholders.

RESULTS

We generated a list of 29 recommendations for managing the solitary pulmonary nodule (SPN) that measures at least 8 to 10 mm in diameter; small, subcentimeter nodules that measure < 8 mm to 10 mm in diameter; and multiple nodules when they are detected incidentally during evaluation of the SPN. Recommendations stress the value of risk factor assessment, the utility of imaging tests (especially old films), the need to weigh the risks and benefits of various management strategies (biopsy, surgery, and observation with serial imaging tests), and the importance of eliciting patient preferences.

CONCLUSION

Patients with pulmonary nodules should be evaluated by estimation of the probability of malignancy, performance of imaging tests to characterize the lesion(s) better, evaluation of the risks associated with various management alternatives, and elicitation of patient preferences for treatment.

Nodular Ground-Glass Opacity at Thin-Section CT: Histologic Correlation and Evaluation of Change at Follow-up

The popularization of computed tomography (CT) in clinical practice and the introduction of mass screening for early lung cancer with the use of CT have increased the frequency of findings of subtle nodules or nodular ground-glass opacity. Nodular ground-glass opacity may be observed in malignancies such as bronchioloalveolar carcinoma and adenocarcinoma, as well as in their putative precursors, such as atypical adenomatous hyperplasia. Nodular ground-glass opacity also may be seen in the presence of benign conditions, including focal interstitial fibrosis, inflammation, and hemorrhage. The persistence of nodular ground-glass opacity over time may be strongly suggestive of an early-stage malignancy, especially if the lesion increases in size or includes a solid component that increases in its extent. Persistent nodular ground-glass opacity also may remain stable in size but show increased attenuation. The more extensive the solid portions of the lesion, the higher the probability of malignancy and the poorer the prognosis. An awareness of the clinical setting, in addition to familiarity with the thin-section CT features of nodular ground-glass opacity at initial and follow-up imaging over several months, can help identify malignancy and achieve an accurate diagnosis. A meticulous evaluation of those CT features, and their correlation with specific histopathologic characteristics, also may enable a more accurate prognosis in cases of neoplastic disease.

Management of an incidentally discovered pulmonary nodule

The incidental finding of a pulmonary nodule on computed tomography (CT) is becoming an increasingly frequent event. The discovery of such a nodule should evoke the possibility of a small bronchogenic carcinoma, for which excision is indicated without delay. However, invasive diagnostic procedures should be avoided in the case of a benign lesion. The objectives of this review article are: (1) to analyze the CT criteria defining benign nodules, nodules of high suspicion of malignancy and indeterminate nodules, (2) to analyze the diagnostic performances and limitations of complementary investigations requested to characterize indeterminate lung nodules, (3) to review the criteria permitting to assess the probability of malignancy of indeterminate nodules and (4) to report on the new guidelines provided by the Fleischner Society for the management of small indeterminate pulmonary nodules, according to their prior probability of malignancy.

Pulmonary Invasive Aspergillosis and Candidiasis in Immunocompromised Patients

The purpose of this study was to compare the high-resolution computed tomography (HRCT) findings of pulmonary invasive aspergillosis and candidiasis in immunocompromised patients. The study included 54 immunocompromised patients (32 men, 22 women; 10 to 68 years of age, median 40 years) with a diagnosis of Aspergillus (n=32) or Candida (n=22) pulmonary infection obtained by sputum culture, bronchoalveolar lavage culture, transbronchial biopsy, surgical biopsy, or autopsy. High-resolution CT images were assessed for the presence and distribution of nodules, consolidation and ground-glass opacities. Presence of the CT halo sign and cavitation was also recorded and the overall distribution of abnormalities was assessed. Comparison was made using the Fisher exact test. Nodules were the most common finding, present in 84% (27 of 32) of patients with aspergillosis and 95% (21 of 22) of patients with candidiasis (P>0.3, Fisher exact test). Centrilobular nodules were more common in patients with aspergillosis (26 of 27, 96%) than in those with candidiasis (11 of 21, 52%) (P<0.001) and random nodules more common in candidiasis (10 of 21, 48%) than in aspergillosis (1 of 27, 4%) (P<0.001). Presence of the CT halo sign, cavitation, and ground-glass opacities was similar in both groups. In summary, pulmonary aspergillosis and candidiasis in immunocompromised patients manifest with similar high-resolution CT findings. Centrilobular nodules and consolidation are more common in aspergillosis. The presence of halo sign or cavitation is not helpful in the differential diagnosis.

Clinical and radiologic predictors of invasive pulmonary aspergillosis in cancer patients: should the European Organization for Research and Treatment of Cancer/Mycosis Study Group (EORTC/MSG) criteria be revised?

BACKGROUND

Invasive pulmonary aspergillosis (IPA) is a life-threatening infection in immunocompromised patients. The outcome of such infections depends on early diagnosis and prompt initiation of therapy. The objective of the current study was to determine the significant predictive factors that characterize IPA in patients with cancer.

METHODS

The clinical characteristics and computed tomography (CT) findings for 47 cases with IPA were retrospectively reviewed and compared with 49 controls (patients diagnosed on autopsy with nonfungal pneumonias). Data from all 96 patients were modeled using multivariate logistic regression. Subgroups of patients with common characteristics and outcomes were identified.

RESULTS

Leukemia, neutropenia, cavitation, and nodular lesions occurred significantly more often among cases than controls (P = 0.04, 0.004, 0.04, and 0.02, respectively). A quantitative scoring system was developed that could be used to identify patients as being at low, medium, and high risk for IPA.

CONCLUSIONS

IPA should be highly suspected in leukemia patients with profound neutropenia, pleuritic chest pain, and cavitary or nodular lesions detected on CT scan. These predictive factors can be used to indicate when early prophylactic and therapeutic antifungal interventions should be initiated.

Pictorial Essay: Multinodular Disease

The evaluation of patients presenting with multinodular pulmonary disease provides an important clinical challenge for physicians. The differential diagnosis includes an extensive list of benign and malignant processes making the management of these cases frequently problematic. With the introduction of high-resolution CT (HRCT) scanning, the ability to assess various patterns of diffuse multinodular disease has evolved into an essential part of the diagnostic process. The purpose of this article is to develop an approach to the diagnosis of multinodular parenchymal disease using HRCT scan pattern recognition as a point of departure.

CT halo sign: the spectrum of pulmonary diseases

The CT halo sign indicates ground glass attenuation surrounding a pulmonary nodule on CT. Although it was initially proposed as an early, specific finding of invasive pulmonary aspergillosis, it can be caused by many other pathological conditions such as infection, neoplastic and inflammatory diseases. The halo of ground glass attenuation pathologically represents pulmonary haemorrhage, tumour infiltration, or non-haemorrhagic inflammatory processes. Although non-specific, this sign is important because the clinical setting and associated radiological features may give a clue to the differential diagnosis. In this review, we demonstrate the spectrum of pulmonary diseases showing the "CT halo sign" on thin-section CT and discuss their radiological and clinical features.

Pulmonary Candidiasis after Hematopoietic Stem Cell Transplantation: Thin-Section CT Findings

PURPOSE

To retrospectively evaluate thin-section computed tomographic (CT) findings in hematopoietic stem cell transplant (ie, bone marrow transplant) patients with histopathologically proved pulmonary candidiasis.

MATERIALS AND METHODS

Ethical approval was obtained from the institutional review board of each of the three institutions; informed consent was not required. The study included 17 hematopoietic stem cell transplant recipients with proved pulmonary candidiasis. Histopathologic specimens were acquired at transbronchial biopsy (n = 8), open lung biopsy (n = 6), and autopsy (n = 3). The patients included seven men and 10 women (age range, 20-62 years; mean age, 37 years). The thin-section CT scans were retrospectively reviewed by two thoracic radiologists for the presence, appearance, and distribution of parenchymal abnormalities.

RESULTS

Multiple nodules were present in 15 (88%) patients, including centrilobular nodules and tree-in-bud pattern in seven (41%) patients. Nodules were bilateral in 12 patients and unilateral in three. An associated halo of ground-glass opacity was identified in five (33%) patients. Nodules were the only CT finding in five patients (29%). Areas of air-space consolidation were identified in 11 (65%) patients. Areas of ground-glass opacity were seen in six (35%) of 17 patients and were always associated with other abnormalities. Other less common CT findings included pleural effusion (n = 3), thickening of the bronchial walls (n = 2), and cavitation (n = 1).

CONCLUSION

The most common thin-section CT findings of pulmonary candidiasis in hematopoietic stem cell transplant patients are multiple bilateral nodular opacities often associated with areas of consolidation.

Imaging of Metastatic Disease to the Thorax

Tumor imaging is at the forefront of radiology technology and is the focus of most cutting edge research. Radiologic applications for imaging of metastases are applied to initial staging, restaging after neoadjuvant therapy, and follow-up surveillance after therapy for tumor recurrence. CT is the routine imaging choice in staging, restaging, and detection of recurrence. Fluorodeoxyglucose-positron emission tomography has evolved as an imaging modality that further improves staging as well as the detection of recurrent and metastatic disease.

The CT halo: a new sign in active pulmonary sarcoidosis

A case of pulmonary sarcoidosis is presented characterized by multiple coalescent nodules and peripheral ground glass halos, which were fully reversible under repeat systemic glucocorticoid treatment. The differential diagnostic aspects of the pulmonary CT halo sign and its potential for indicating active reversible disease in patients with sarcoidosis is discussed.