Bruno Hochhegger

High-resolution computed tomography findings from adult patients with Influenza A (H1N1) virus-associated pneumonia

OBJECTIVE The aim of this study was to assess the high-resolution computed tomography (HRCT) findings at presentation in patients diagnosed with Influenza A (H1N1) virus-associated pneumonia. MATERIALS AND METHODS We reviewed the HRCT findings from 20 patients diagnosed with Influenza A (H1N1) and compared their HRCT scans with chest radiographs, obtained on the same day. The imaging studies were obtained 4-9 days after the onset of symptoms. The patients included 11 men and 9 women (ages 24-62 years; mean 42.7 years). All patients had a body temperature greater than 100.4 degrees F (>38 degrees C), tachypnea, and cough. Other common symptoms included diarrhea (60%) and sore throat (30%). The radiographs and HRCT scans were reviewed independently by two observers who reached a consensus decision. RESULTS The predominant HRCT findings consisted of bilateral ground-glass opacities (n=12), bilateral areas of consolidation (n=2), or a mixed bilateral pattern of ground-glass opacities and areas of consolidation (n=6). The abnormalities were bilateral in all of the 20 patients, had a predominantly sub-pleural distribution in 13 patients, and had a random distribution in the remaining 7 patients. The predominant radiographic findings were consolidations. Normal radiographs were found in 4 out of the 20 patients. CONCLUSION HRCT may reveal parenchymal abnormalities in patients with Influenza A (H1N1) infection who have normal findings on radiographs. The predominant HRCT findings were bilateral, peripheral, ground-glass opacities and/or bilateral areas of consolidation. The patients who presented consolidations had more severe clinical course.

Reversed Halo Sign: High-Resolution CT Scan Findings in 79 Patients

BACKGROUND The purpose of this study was to evaluate the high-resolution CT (HRCT) scan findings of patients with the reversed halo sign (RHS) and to identify distinguishing features among the various causes. METHODS Two chest radiologists reviewed the HRCT scans of 79 patients with RHS and determined the CT scan findings by consensus. We studied the morphologic characteristics, number of lesions, and presence of features associated with RHS. RESULTS Forty-one patients presented with infectious diseases (paracoccidioidomycosis, TB, zygomycosis, invasive pulmonary aspergillosis, Pneumocystis jiroveci pneumonia, histoplasmosis, cryptococcosis), and 38 presented with noninfectious diseases (cryptogenic organizing pneumonia, pulmonary embolism, sarcoidosis, edema, lepidic predominant adenocarcinoma [formerly bronchiolo-alveolar carcinoma], granulomatosis with polyangiitis [Wegener]). The RHS walls were smooth in 58 patients (73.4%) and nodular in 21 patients (26.6%). Lesions were multiple in 40 patients (50.6%) and single in 39 patients (49.4%). CONCLUSION The presence of nodular walls or nodules inside the halo of the RHS is highly suggestive of granulomatous diseases.

Exogenous lipoid pneumonia. Clinical and radiological manifestations

Lipoid pneumonia results from the pulmonary accumulation of endogenous or exogenous lipids. Host tissue reactions to the inhaled substances differ according to their chemical characteristics. Symptoms can vary significantly among individuals, ranging from asymptomatic to severe, life-threatening disease. Acute, sometimes fatal, cases can occur, but the disease is usually indolent. Possible complications include superinfection by nontuberculous mycobacteria, pulmonary fibrosis, respiratory insufficiency, cor pulmonale, and hypercalcemia. The radiological findings are nonspecific, and the disease presents with variable patterns and distribution. For this reason, lipoid pneumonia may mimic many other diseases. The diagnosis of exogenous lipoid pneumonia is based on a history of exposure to oil, characteristic radiological findings, and the presence of lipid-laden macrophages on sputum or BAL analysis. High-resolution computed tomography (HRCT) is the best imaging modality for the diagnosis of lipoid pneumonia. The most characteristic CT finding in LP is the presence of negative attenuation values within areas of consolidation. There are currently no studies in the literature that define the best therapeutic option. However, there is a consensus that the key measure is identifying and discontinuing exposure to the offending agent. Treatment in patients without clinical symptoms remains controversial, but in patients with diffuse pulmonary damage, aggressive therapies have been reported. They include whole lung lavage, systemic corticosteroids, and thoracoscopy with surgical debridement.

Clinical and Imaging Manifestations of Hemorrhagic Pulmonary Leptospirosis: A State-of-the-Art Review

Leptospirosis, a spirochetal zoonosis, is frequently unrecognized due to its manifestation as an undifferentiated fever. It is an emerging infectious disease that has changed from an occupational disease of veterinarians, farmers, butchers, and other animal handlers to a cause of epidemics in poor and decayed urban communities in developing countries. Humans are infected when mucous membranes or abraded skin come into direct contact with the urine of infected animals, especially rats and dogs. Mortality from severe leptospirosis is high, even when optimal treatment is provided. The diagnosis of leptospirosis is based on clinical findings, history of direct or indirect exposure to infected animals in endemic areas, and positive serological tests. It should be considered in the differential diagnosis of patients with febrile illnesses associated with pneumonitis and respiratory failure, especially when hemoptysis is present. Severe pulmonary involvement in leptospirosis consists primarily of hemorrhagic pneumonitis. In advanced cases, adult respiratory distress syndrome and massive pulmonary hemorrhage may occur. Chest radiographs show bilateral alveolar infiltrates and/or resemble viral pneumonia, bronchopneumonia, tuberculosis, adult respiratory distress syndrome, and other causes of pulmonary hemorrhage such as Goodpasture syndrome. High-resolution computed tomography scans may show nodular infiltrates, areas of consolidation, ground-glass attenuation, and crazy-paving patterns. Bronchoalveolar lavage and autopsy studies have suggested that ground-glass opacities and air-space consolidations are secondary to pulmonary hemorrhage. Although not specific, the presence of these computed tomography findings in a febrile patient with an appropriate history should suggest a diagnosis of leptospirosis.

Reversed Halo Sign on Computed Tomography: State-of-the-Art Review

The reversed halo sign (RHS) is a chest computed tomography (CT) pattern defined as a focal round area of ground-glass attenuation surrounded by a crescent or ring of consolidation. The RHS was first described as being relatively specific for cryptogenic organizing pneumonia but was later observed in several other infectious and noninfectious diseases. Although the presence of the RHS on CT may help narrow the range of diseases considered in differential diagnoses, final diagnoses should be based on correlation with the clinical scenario and the presence of additional disease-specific CT findings. However, frequently a biopsy may be needed to establish the diagnosis. Organizing pneumonia is the most frequent cause of the RHS. This is a distinct clinical and pathologic entity that can be cryptogenic or secondary to other known causes. Morphologic aspects of the halo, particularly the presence of small nodules in the wall or inside the lesion, usually indicate an active granulomatous disease (tuberculosis or sarcoidosis) rather than organizing pneumonia. Immunocompromised patients presenting with the RHS on CT examination should be considered to have an infection until further analyses prove otherwise. Pulmonary zygomycosis and invasive pulmonary aspergillosis are typically seen in patients with severe immunosuppression, most commonly secondary to hematological malignancies. Other causes of the RHS include noninvasive fungal infections such as paracoccidioidomycosis, histoplasmosis, and Pneumocystis jiroveci pneumonia. Furthermore, Wegener’s granulomatosis, radiofrequency ablation, and lymphomatoid granulomatosis may also lead to this finding. Based on a search of the PubMed and Scopus databases, we review the different diseases that can manifest with the RHS on CT.

CT Quantification of Emphysema in Young Subjects with No Recognizable Chest Disease

OBJECTIVE The purpose of this prospective study was to evaluate volumetric CT emphysema quantification (CT densitovolumetry) in a young population with no recognizable lung disease. SUBJECTS AND METHODS A cohort of 30 nonsmoking patients with no recognizable lung disease (16 men, 14 women; age range, 19-41 years) underwent inspiratory and expiratory CT, after which the data were postprocessed for volumetric quantification of emphysema (threshold, -950 HU). Correlation was tested for age, weight, height, sex, body surface area (BSA), and physical activity. Normal limits were established by mean +/- 1.96 SD. RESULTS No correlation was found between the measured volumes and age or physical activity. Correlation was found between BSA and normal lung volume in inspiration (r = 0.69, p = 0.000), shrink volume (i.e., difference in total lung volume in inspiration and in expiration) (r = 0.66, p = 0.000), and percentage of shrink volume (r = 0.35, p = 0.05). For an alpha error of 5%, the limits of normality based on this sample are percentage of emphysema in inspiration, 0.35%; percentage of emphysema in expiration, 0.12%; and maximum lung volume in expiration, 3.6 L. The maximum predicted percentage of shrink volume can be calculated as %SV = 29.43% + 16.97% x BSA (+/- 1.96 x 7.61%). CONCLUSION Young healthy nonsmokers with no recognizable lung disease can also show a small proportion of emphysematous-like changes on CT densitovolumetry when a threshold of -950 HU is used. Reference values should be considered when applying the technique for early detection or grading of emphysema and when studying aging lungs.

Pulmonary alveolar microlithiasis. State-of-the-art review.

Pulmonary alveolar microlithiasis (PAM) is a rare genetic lung disease characterized by calcifications within the alveoli. Mutations in the SLC34A2 gene, which encodes a type IIb sodium-phosphate cotransporter, are responsible for this disease, leading to intra-alveolar accumulation of phosphate that favors the formation of microliths. The hallmark of this disorder is clinical-radiological dissociation, with typical imaging findings that correlate well with specific pathological findings. The long-term prognosis is poor and no treatment has been discovered to date. The aim of this review is to describe the main pathological, clinical, and imaging aspects of PAM, ranging from its genetic basis to treatment.

Lipoid pneumonia in 53 patients after aspiration of mineral oil: comparison of high-resolution computed tomography findings in adults and children.

Objective: To evaluate the high-resolution computed tomography (HRCT) findings in 53 patients with exogenous lipoid pneumonia and to compare the imaging features of adults and children. Materials and Methods: The study included 35 children and 18 adults. Statistical comparisons of findings in the 2 age groups were performed using either Pearson &khgr;2 or Fisher exact test, as appropriate, at 5% significance level. Results: The main HRCT findings included air-space consolidation, ground glass attenuation, air-space nodules, and crazy-paving pattern. Abnormalities predominated in the posterior regions of the right lung. The right lower lobe was most likely to show severe involvement. Conclusions: The presence of air-space consolidation, the involvement of upper right lobe, and the central and posterior distribution of the lesions were more common in children, whereas the crazy-paving pattern and random localization were significantly more frequent in adults. The other findings were not different between the 2 groups.

MRI in lung cancer: a pictorial essay

Imaging studies play a critical role in the diagnosis and staging of lung cancer. CT and 18-fluorodeoxyglucose positron emission tomography CT (PET/CT) are widely and routinely used for staging and assessment of treatment response. Many radiologists still use MRI only for the assessment of superior sulcus tumours, and in cases where invasion of the spinal cord canal is suspected. MRI can detect and stage lung cancer, and this method could be an excellent alternative to CT or PET/CT in the investigation of lung malignancies and other diseases. This pictorial essay discusses the use of MRI in the investigation of lung cancer.

Infectious Diseases Causing Diffuse Alveolar Hemorrhage in Immunocompetent Patients: A State-of-the-Art Review

Diffuse alveolar hemorrhage (DAH) represents a syndrome that can complicate many clinical conditions and may be life-threatening, requiring prompt treatment. It is recognized by the signs of acute- or subacute-onset cough, hemoptysis, diffuse radiographic pulmonary infiltrates, anemia, and hypoxemic respiratory distress. DAH is characterized by the accumulation of intra-alveolar red blood cells originating most frequently from the alveolar capillaries. It must be distinguished from localized pulmonary hemorrhage, which is most commonly due to chronic bronchitis, bronchiectasis, tumor, or localized infection. Hemoptysis, the major sign of DAH, may develop suddenly or over a period of days to weeks; this sign may also be initially absent, in which case diagnostic suspicion is established after sequential bronchoalveolar lavage reveals worsening red blood cell counts. The causes of DAH can be divided into infectious and noninfectious, the latter of which may affect immunocompetent or immunodeficient patients. Pulmonary infections are rarely reported in association with DAH, but they should be considered in the diagnostic workup because of the obvious therapeutic implications. In immunocompromised patients, the main infectious diseases that cause DAH are cytomegalovirus, adenovirus, invasive aspergillosis, Mycoplasma, Legionella, and Strongyloides. In immunocompetent patients, the infectious diseases that most frequently cause DAH are influenza A (H1N1), dengue, leptospirosis, malaria, and Staphylococcus aureus infection. Based on a search of the PubMed and Scopus databases, we review the infectious diseases that may cause DAH in immunocompetent patients.