Invasive pulmonary aspergillosis: evaluation with MR imaging

Eleven patients with suspected invasive pulmonary aspergillosis underwent magnetic resonance (MR) imaging. Images were obtained with standard spin-echo sequences and electrocardiographic triggering before and after intravenous administration of gadolinium diethylenetriaminepentaacetic acid. Thirty-seven of 48 lesions seen on MR images were nodular infiltrates; 34 of these had a targetlike appearance, with hypointense centers and iso- or hyperintense rims. Twenty-three of 37 nodular lesions contained areas of hyperintensity on T1-weighted images. All 37 had enhanced rims on postcontrast MR images. The remaining 11 lesions were segmental infiltrates, seven of which were predominantly hyperintense on T1-weighted images. In one patient with nodular lesions, MR imaging findings were correlated with those from pathologic analysis of a resected upper lobe. Areas of hyperintensity corresponded to subacute hemorrhage permeated by Aspergillus organisms. The authors believe that the typical targetlike appearance of nodular lesions on MR images and the potential that MR imaging has to reveal hemorrhagic content will prove useful in the early diagnosis of invasive pulmonary aspergillosis.     

Persistent pulmonary nodular ground-glass opacity at thin-section CT: histopathologic comparisons

PURPOSE: To retrospectively compare pure pulmonary ground-glass opacity (GGO) nodules observed on thin-section computed tomography (CT) images with histopathologic findings. MATERIALS AND METHODS: The institutional review board approved this study and waived informed consent. Histopathologic specimens were obtained from 53 GGO nodules in 49 patients. CT scans were assessed in terms of nodule size, shape, contour, internal characteristics, and the presence of a pleural tag. The findings obtained were compared with histopathologic results. Differences in thin-section CT findings according to histopathologic diagnoses were analyzed by using the Kruskal-Wallis test or Fisher exact test. RESULTS: Of 53 nodules in 49 patients (20 men, 29 women; mean age, 54 years; range, 29-78 years), 40 (75%) proved to be broncholoalveolar cell carcinoma (BAC) (n=36) or adenocarcinoma with predominant BAC component (n=4), three (6%) atypical adenomatous hyperplasia, and 10 (19%) nonspecific fibrosis or organizing pneumonia. No significant differences in morphologic findings on thin-section CT scans were found among the three diseases (all P>0.05). A polygonal shape (25%, 10 of 40 nodules) and a lobulated or spiculated margin (45%, 18 of 40) in BAC or adenocarcinoma with predominant BAC component were caused by interstitial fibrosis or infiltrative tumor growth. A polygonal shape and a lobulated or spiculated margin were observed in two (20%) and three (30%) of 10 nodules, respectively, in organizing pneumonia/fibrosis were caused by granulation tissue aligned in a linear manner in perilobular regions with or without interlobular septal thickening. CONCLUSION: About 75% of persistent pulmonary GGO nodules are attributed to BAC or adenocarcinoma with predominant BAC component, and at thin-section CT, these nodules do not manifest morphologic features that distinguish them from other GGO nodules with different histopathologic diagnoses.     

Hydrostatic pulmonary edema: evaluation with thin-section CT in dogs

PURPOSE: To identify the hemodynamic determinants of ground-glass opacification on thin-section computed tomographic (CT) scans of hydrostatic pulmonary edema and to compare attenuation and subjective assessments of ground-glass opacification with extravascular lung water. MATERIALS AND METHODS: Left atrial pressure, pulmonary arterial pressure, effective pulmonary capillary pressure, and extravascular lung water were measured in six dogs before and during progressive increase of effective pulmonary capillary pressure. A thin-section CT scan was obtained at each step. Lung attenuation and subjective assessments of ground-glass opacification were compared with hemodynamic variables and extravascular lung water. RESULTS: Ground-glass opacification was identified when effective pulmonary capillary pressure equaled critical pulmonary capillary pressure. Extravascular lung water increased, and the distribution curve of lung attenuation coefficients shifted to higher attenuation from the second measurement at an effective pulmonary capillary pressure greater than the critical pulmonary capillary pressure. Attenuation was highly correlated (r = 0.98, P < .001) with extravascular lung water; ground-glass opacification was detected before a significant (P = .615, analysis of variance) increase in extravascular lung water. CONCLUSION: Thin-section CT depicts ground-glass opacification when effective pulmonary capillary pressure equals critical pulmonary capillary pressure and before a detectable increase in extravascular lung water. Attenuation reflects extravascular lung water.     

Early pulmonary involvement in ankylosing spondylitis: assessment with thin-section CT

AIM: To determine the frequency and the distribution of early pulmonary lesions in patients with ankylosing spondylitis (AS) and a normal chest X-ray on thin-section CT and to correlate the CT findings with the results of pulmonary function tests and clinical data. MATERIALS AND METHODS: Twenty-five patients with clinically proven AS and no history of smoking underwent clinical examinations, pulmonary function tests (PFT), chest radiography, and thin-section CT. Four of 25 patients (16%), who had obvious signs on plain films suggestive of pre-existing disorders unrelated to AS were excluded. RESULTS: Fifteen of 21 patients (71%) had abnormalities on thin-section CT. The most frequent abnormalities were thickening of the interlobular septa in seven of 21 patients (33%), mild bronchial wall thickening in (6/21, 29%), pleural thickening and pleuropulmonary irregularities (both 29%) and linear septal thickening (6/21, 29%). In six patients there were no signs of pleuropulmonary involvement. Eight of 15 patients (53%) with abnormal and four of six patients (67%) with normal CT findings revealed mild restrictive lung function impairment. CONCLUSION: Patients with AS but a normal chest radiograph frequently have abnormalities on thin-section CT. As these abnormalities are usually subtle and their extent does not correlate with functional and clinical data, the overall routine impact of thin-section CT in the diagnosis of AS is limited.     

Minute pulmonary meningothelial-like nodules: thin-section CT appearance

Minute pulmonary meningothelial-like nodules are often incidentally discovered during pathologic evaluation of pulmonary parenchymal specimens. These lesions were once thought to represent pulmonary chemodectomas, but pathological studies have shown that they are not of neuroendocrine origin. Minute pulmonary meningothelial-like nodules are benign, perhaps reactive in nature, but are occasionally found in association with lung carcinoma. They may appear as randomly distributed well-defined micronodules on thin-section chest CT, and thus may simulate metastatic disease when associated with lung carcinoma.     

Semiinvasive pulmonary aspergillosis: CT and pathologic findings in six patients

OBJECTIVE: We describe the chest CT and pathologic findings of semiinvasive pulmonary aspergillosis in six patients. CONCLUSION: Semiinvasive pulmonary aspergillosis should be considered in the mildly immunocompromised patient with CT findings that reveal persistent parenchymal abnormalities. Patterns include consolidation and mass.     

Volumetric thin-section CT: evaluation of pulmonary interlobar fissures

PURPOSE

We aimed to perform an imaging analysis of interlobar fissures and their variations using thin-section computed tomography (CT).

METHODS

Volumetric thin-section CT scanning was performed in 208 subjects. Interlobar fissures were observed on axial images, and reconstructed coronal and sagittal images were observed by multi-planar reformatting (MPR). The vessel distributions were verified by maximal intensity projection (MIP). On the axial images, the interlobar fissures were characterized by lines of hyperattenuation, bands of hyperattenuation, avascular zones, and mixed imaging. The interlobar fissures were divided into seven grades according to the percentage of defects over the entire fissure.

RESULTS

On the axial images, of all interlobar fissures without avascular zones, 70.2% of the right oblique fissures (ROFs) and 94.2% of the left oblique fissures (LOFs) appeared as lines, and 83.2% of the horizontal fissures (HFs) appeared as bands. All of the interlobar fissures appeared as lines on the coronal and sagittal images. Of all cases, 17.8% showed fully complete interlobar fissures for all three fissures. Incomplete fissures included 41.3% of ROFs, 58.2% of HFs, and 45.2% of LOFs. In ROFs and LOFs, discontinuity was most frequently below 20%, while in HFs discontinuity was most frequently 41%–60%. The most common classification of incomplete interlobar fissures was a discontinuous avascular zone.

CONCLUSION

Incomplete interlobar fissures are common variations of interlobar fissures. Techniques including volumetric thin-section CT, MPR, and MIP can assist in the diagnosis of incomplete interlobar fissures.The pulmonary interlobar fissures are important landmarks for pulmonary anatomy. They adopt a double membrane structure formed by invagination of the visceral pleura. The interlobar fissures are 1–3 mm thick and consist of the right oblique fissure (ROF), horizontal fissure (HF), and left oblique fissure (LOF) (1, 2). The recognition of pulmonary interlobar fissures and their variations is beneficial for identifying pulmonary lesion locations, evaluating disease progression, selecting surgical operations, and applying endoscopic therapy (3–5). With the constant development of imaging techniques, thin-section computed tomography (CT) can provide more detailed information regarding lung structure with respect to the anatomy (5–7). Multiplanar reformatting (MPR) (8) and maximal intensity projection (MIP) are reconstruction techniques based on a noninvasive methodology that detect pulmonary interlobar fissure variations. The results generated by these techniques highly resemble the results of an autopsy (8). In this study, the pulmonary interlobar fissures and their variations were investigated and analyzed by volumetric thin-section MPR and MIP images.     

Bilateral bronchiectasis and bronchiolitis at thin-section CT: diagnostic implications in nontuberculous mycobacterial pulmonary infection

PURPOSE: To determine frequency of nontuberculous mycobacterial (NTM) pulmonary infection in patients with bilateral bronchiectasis and bronchiolitis at chest computed tomography (CT) and whether CT findings are indicative of Mycobacterium avium-intracellulare complex (MAC) infection. MATERIALS AND METHODS: Institutional review board approved this research study; patient informed consent (not required) was obtained from all patients to perform CT. From July 2000 to December 2002, 126 consecutive patients, who were suspected of having NTM pulmonary infection at helical CT (120 kVp, 70 mA, 2.5-mm collimation, pitch of 6) with findings of bilateral bronchiectasis and bronchiolitis, were included. Of these, 105 patients underwent study for diagnosis of NTM disease. Medical records and CT scans were reviewed for final diagnoses. Clinical and chest CT findings in patients with NTM disease and those with other airway diseases were compared (unpaired t test, chi(2) test, or Fisher exact test). RESULTS: NTM pulmonary infection was seen in 36 (34%) of 105 patients; NTM was definite in 32 (30%) and probable in four (4%). In decreasing order of frequency, organisms involved were MAC in 18 patients (50%), with M avium in 10 and M intracellulare in eight, Mycobacterium abscessus in 14 (39%), Mycobacterium kansasii in one (3%), and Mycobacterium fortuitum in one (3%); organisms were unidentifiable in two (6%). Female (P = .031) nonsmokers (P = .037) with history of treatment for Mycobacterium tuberculosis (P = .002), sputum smear positive for acid-fast bacilli (P < .001), and thin-section CT findings of bronchiolitis in more than five lobes with bronchiectasis (P = .011), lobular consolidation (P = .010), and a cavity (P < .001) were related to diagnosis of NTM pulmonary infection. CONCLUSION: About one-third of patients with thin-section CT findings of bilateral bronchiectasis and bronchiolitis have NTM pulmonary infection; in these situations, MAC and M abscessus are two most frequent causative organisms. Thin-section CT findings of bronchiectasis and bronchiolitis involving more than five lobes, especially when associated with lobular consolidation or a cavity, are highly suggestive of NTM pulmonary infection.     

Invasive pulmonary aspergillosis: possibility of radiologic diagnosis]

The incidence of invasive pulmonary aspergillosis is increasing in the patients with malignant hematologic diseases; this occurs in the phase of granulocytopenia induced by chemotherapy. In these cases an early diagnosis is mandatory to start a prompt antimycotic treatment. The authors reviewed the personal series of 56 patients with malignant hematologic diseases who, in the phase of granulocytopenia, developed a pulmonary lesion: 32/56 with invasive pulmonary aspergillosis; 8/56 with Candida and 16/56 with bacterial infection. All patients underwent several conventional radiologic controls: 9 cases with invasive pulmonary aspergillosis were also studied with Computed Tomography (CT). After a short pathologic introduction, the conventional radiologic and CT patterns of invasive pulmonary aspergillosis are analyzed, both at onset and over its evolutive phase. The most significant feature for an early conventional radiologic diagnosis is the nodular pattern--single or multiple--; this allowed a correct diagnosis, at onset, of 20/32 (62%) invasive pulmonary aspergillosis cases. CT provided a further diagnostic contribution by showing a peri-nodular halo. Of interest was also the CT demonstration of high-density pleural thickening adjacent to the mycotic lesion, probably due to fungal involvement of the sub-pleural space. The routine chest roentgenogram is the modality of choice; CT may be useful in questionable cases.     

Longitudinal follow-up study of smoker's lung with thin-section CT in correlation with pulmonary function tests.

PURPOSE: To evaluate thin-section computed tomography (CT) in depicting longitudinal changes in the lung parenchyma. MATERIALS AND METHODS: One hundred eleven volunteers underwent sequential examination with thin-section CT and pulmonary function tests over a mean period of 5.5 years. According to their smoking habits between initial evaluation (T0) and follow-up (T1), the subjects were classified as persistent current smokers (n = 57), persistent nonsmokers (n = 31), persistent ex-smokers (n = 13), or quitters (n = 10). RESULTS: Significant differences in CT findings between T0 and T1 were seen in only the group of persistent current smokers, who showed a higher frequency of emphysema (40% vs 26%; P =.005) and ground-glass attenuation (42% vs 28%; P =.02). Individual analysis of follow-up CT scans in the 19 persistent current smokers with micronodules at T0 demonstrated (a) no changes in seven cases, (b) a higher profusion of micronodules in seven cases, and (c) replacement of micronodules with emphysema in five cases. Subjects with emphysema and/or areas of ground-glass attenuation at T0 had a significantly more rapid decline in lung function than did those with a normal CT scan. CONCLUSION: Emphysema and/or ground-glass attenuation are linked with impairment of ventilatory lung function over time in persistent current smokers.     

Comparison of 133Xe gas dynamic SPECT and thin-section CT in patients with pulmonary emphysema

PURPOSE: We assessed 133Xe gas dynamic single photon emission computed tomography (SPECT) by comparing washout axial images with thin-section CT (TSCT) in patients with pulmonary emphysema. METHODS: Twenty-three patients were studied. All patients were diagnosed as having pulmonary emphysema on the basis of TSCT. We compared TSCT of upper, middle and lower lung fields with 133Xe gas dynamic SPECT axial images at the corresponding levels during the 3 to 4 minutes of washout phase. If the degree of 133Xe gas retention or TSCT finding of ventral and dorsal parts was not the same, the images were divided into two parts. RESULTS: A total of 174 lesions in 23 cases were examined, but 3 lesions having no retention of 133Xe gas at equilibrium phase were excluded. The results showed that: there were 37 lesions (21.6%) with equivalent severity on both images; there were 42 lesions (24.5%) with more severity on 133Xe gas dynamic SPECT than on TSCT; and there were 92 lesions (53.8%) with more severity on TSCT than on 133Xe gas dynamic SPECT. The severity on 133Xe gas dynamic SPECT and TSCT was not always compatible. One of the reasons for the variable 133Xe gas retention even when the lesion had the same severity on TSCT, may be bronchial stricture which cannot be seen on TSCT. CONCLUSION: By comparison of axial images of 133Xe gas dynamic SPECT with CT images, we could recognize the areas of 133Xe gas retention in detail. Results suggest that 133Xe gas dynamic SPECT can be useful to identify ventilation impairment in pulmonary emphysema.     

Frequency and significance of pulmonary nodules on thin-section CT in patients with extrapulmonary malignant neoplasms

Purpose

To determine the frequency and significance of pulmonary nodules detected on thin-section CT in patients with extrapulmonary malignant neoplasms.

Materials and methods

The institutional review board approved this study. This study retrospectively evaluated 308 patients with extrapulmonary carcinomas or sarcomas and had undergone thin-section chest CT (2 mm slice thickness) for staging. Three radiologists identified non-calcified nodules and evaluated the size, the growth and the distance from the nearest pleural surface. The characteristics of the nodules were defined based on the results of either a diagnostic biopsy or nodule growth.

Results

One or more non-calcified pulmonary nodules were detected in 75% of the patients (233/308). One hundred and thirty-seven of these patients had nodules that met the criteria of either benign or malignant nodules. Nodules smaller than 10 mm were more likely to be benign, whereas those 10 mm or greater were more likely to be malignant (22/26, 85%; P < .0001). Most nodules less than 10 mm from the pleura were benign (91%), whereas approximately half of the nodules 10 mm or more away from the pleura were malignant (20/43, 47%; P < .0001). Patients with melanoma, sarcoma, or testicular carcinoma were more likely to have malignant nodules. A multivariable analysis demonstrated the nodule size (P < .0001) and distance from the pleura were predictive of malignancy.

Conclusion

The nodule detection rate on thin-section CT in patients with extrapulmonary malignancy is high. Most of the nodules smaller than 10 mm or less than 10 mm from the pleura are benign.     

Invasive pulmonary aspergillosis: frequency and meaning of the "hypodense sign" on unenhanced CT

The purpose of this study was to establish the diagnostic value of central hypointensity ("hypodense sign") in lung consolidations or nodules, in severely immunocompromised or neutropenic patients, suspected of having invasive pulmonary aspergillosis (IPA), and to assess its recognition on unenhanced CT scans. Serial CT scans of the lung were retrospectively reviewed in 43 consecutive immunosuppressed patients with IPA, and assessed for the presence of the hypodense sign using standard mediastinal and lung windowing settings, as well as a special, narrower window setting (width 110-140 HU; level 15-40 HU). The temporal relationship between the occurrence of the first CT-finding suspicious of IPA and the appearance of the hypodense sign, as well as between this and the occurrence of the crescent sign, cavitation or reduction in lesion size, was evaluated. Additionally, CT-scans from 89 immunocompromised patients with viral (n=45) or bacterial (n=44) pneumonia, investigated in the same time period at our institution were reviewed, with respect to the presence of the "hypodense" sign. Unenhanced CT scans revealed the hypodense sign in 11 neutropenic patients and 2 severely immunocompromised patients, out of a total of 43 patients with IPA evaluated in this study (30.2%). The mean time between the appearance of the first CT-findings of IPA (large nodule or consolidation +/- positive halo sign) and the hypodense sign was 7.8 days, while the time interval between the hypodense sign and the occurrence of crescent sign, cavitation, or decrease of the lesion's size was 8.3 days. The hypodense sign did not occur in any of the patients with viral or bacterial pneumonia, in the control series. We consider the hypodense sign to be a supplementary tool in the diagnosis of IPA. Its sensitivity was low in our series, but the high specificity makes it valuable in predicting IPA, anticipating the occurrence of cavitation or crescent sign, which are considered specific, but late findings of IPA. The hypodense sign is recognizable also on unenhanced CT, when a narrower lung window setting is used.     

Organizing pneumonia: perilobular pattern at thin-section CT

PURPOSE: To describe the appearance and frequency of a perilobular pattern at thin-section computed tomography (CT) in patients with organizing pneumonia. MATERIALS AND METHODS: Thin-section CT scans of 21 consecutive patients with cryptogenic organizing pneumonia were retrospectively reviewed. Two thoracic radiologists in consensus recorded the presence and distribution of the CT abnormalities (consolidation, ground-glass opacification, nodules, bandlike opacities, interlobular septal thickening, and findings of fibrosis), with a particular focus on the presence and predominant location of the perilobular pattern, that is, a poorly defined arcadelike or polygonal appearance. RESULTS: The perilobular pattern was present in 12 (57%) of 21 patients, 10 of whom had five or more perilobular opacities. Other CT features were consolidation (20 patients, 95%), which was predominantly a subpleural and/or peribronchial distribution in 17 patients, and ground-glass opacification (18 patients, 86%). Bandlike opacities and interlobular septal thickening were observed in four patients and one patient, respectively. The perilobular pattern abutted the pleural surface in 10 of 12 patients and was surrounded by aerated lung parenchyma in 11 of 12 patients. There was no obvious relationship between perilobular opacities and CT findings indicative of established fibrosis. CONCLUSION: A perilobular pattern was present in more than half of the patients, along with the expected thin-section CT features of organizing pneumonia.     

Nontuberculous mycobacterial pulmonary infection in immunocompetent patients: comparison of thin-section CT and histopathologic findings

PURPOSE: To identify and describe the thin-section computed tomographic (CT) findings of nontuberculous mycobacterial (NTM) pulmonary infection in immunocompetent patients and to compare these findings with histopathologic findings. MATERIALS AND METHODS: Between April 2002 and March 2003, the thin-section chest CT findings in and histopathologic lung tissue specimens from 22 patients who fulfilled the American Thoracic Society diagnostic criteria for NTM pulmonary infection were retrospectively reviewed. The lung lesion patterns (ie, small nodules, branching centrilobular nodules [ie, tree-in-bud pattern], consolidation, cavities, bronchiectasis, and volume loss) seen at CT at the sites of transbronchial lung biopsy (n = 22) or lobectomy (n = 1) were compared with the histopathologic findings. RESULTS: Thirteen of the 22 patients were found to have Mycobacterium abscessus pulmonary infection; seven, to have Mycobacterium avium-intracellulare complex infection; and two, to have Mycobacterium fortuitum infection. Regardless of the specific infective mycobacterial species, bilateral small nodules (in 22 [100%] lung locations), cylindric bronchiectasis (in 20 [91%] locations), and branching centrilobular nodular lesions (in 17 [77%] locations) were the most common CT findings seen at the biopsy sites. All of the transbronchial lung biopsy specimens showed a thickened bronchiolar wall and bronchiolar and peribronchiolar inflammation at histopathologic analysis. Dilated bronchioles were identified in 19 (86%) patients, and epithelioid granulomas with or without caseation were seen in seven (32%). CONCLUSION: Regardless of the specific infective mycobacterial species, the most common thin-section CT findings of NTM pulmonary infection are bilateral small nodules, cylindric bronchiectasis, and branching centrilobular nodules. These findings correspond histopathologically to bronchiolectasis and bronchiolar and peribronchiolar inflammation with or without granuloma formation.