Radiologic-pathologic correlations of small lung nodules with special reference to peribronchiolar nodules

Ex-vivo 1.5T MR Imaging versus CT in Estimating the Size of the Pathologically Invasive Component of Lung Adenocarcinoma Spectrum Lesions

PURPOSE

The purpose of this study was to investigate whether ex-vivo MRI enables accurate estimation of the invasive component of lung adenocarcinoma.

METHODS

We retrospectively reviewed 32 patients with lung adenocarcinoma who underwent lung lobectomy. The specimens underwent MRI at 1.5T. The boundary between the lesion and the normal lung was evaluated on a 5-point scale in each three MRI sequences, and a one-way analysis of variance and post-hoc tests were performed. The invasive component size was measured histopathologically. The maximum diameter of each solid component measured on CT and MR T1-weighted (T1W) images and the maximum size obtained from histopathologic images were compared using the Wilcoxon signed-rank test. Inter-reader agreement was evaluated using intraclass correlation coefficients (ICC).

RESULTS

T1W images were determined to be optimal for the delineation of the lesions (P < 0.001). The histopathologic invasive area corresponded to the area where the T1W ex-vivo MR image showed a high signal intensity that was almost equal to the intravascular blood signal. The maximum diameter of the solid component on CT was overestimated compared with the maximum invasive size on histopathology (mean, 153%; P < 0.05), while that on MRI was evaluated mostly accurately without overestimation (mean, 108%; P = 0.48). The interobserver reliability of the measurements using CT and MRI was good (ICC = 0.71 on CT, 0.74 on MRI).

CONCLUSION

Ex-vivo MRI was more accurate than conventional CT in delineating the invasive component of lung adenocarcinoma.

A comparison of the chest radiographic and computed tomographic features of subclinical pulmonary tuberculosis

Subclinical pulmonary tuberculosis (PTB) is a recently described intermediate state of great interest, but about which little is known. This study sought to describe and compare the frequency of key radiologic features of subclinical PTB on chest radiograph (CXR) versus computed tomographic scan (CT), and to interpret the clinical and public health relevance of the differences. Diagnostic CXRs and CT scans of the thorax and neck in a 16-year cohort of subclinical PTB patients in Canada were re-acquired and read by two independent readers and arbitrated by a third reader. Logistic regression models were fit to determine how likely CXR features can be detected by CT scan versus CXR after adjustment for age and sex. Among 296 subclinical patients, CXRs were available in 286 (96.6%) and CT scans in 94 (32.9%). CXR features in patients with and without CT scans were comparable. Lung cavitation was 4.77 times (95% CI 1.95–11.66), endobronchial spread 19.36 times (95% CI 8.05–46.52), and moderate/far-advanced parenchymal disease 3.23 times (95% CI 1.66–6.30), more common on CT scan than CXR. We conclude that the extent to which CXRs under-detect key radiologic features in subclinical PTB is substantial. This may have public health and treatment implications.

Prototype Ultrahigh-Resolution Computed Tomography for Chest Imaging: Initial Human Experience

OBJECTIVE

The objective of this study was to evaluate a prototype, ultrahigh-resolution computed tomography offering higher reconstruction matrix (1024 × 1024) and spatial resolution (0.15 mm) for chest imaging.

METHODS

Higher (1024) matrix reconstruction enabled by ultrahigh-resolution computed tomography scanner (128-detector rows; detector width, 0.25 mm; spatial resolution, 0.15 mm) was compared with conventional (512) reconstruction with image quality grading on a Likert scale (1, excellent; 5, nondiagnostic) for image noise, artifacts, contrast, small detail, lesion conspicuity, image sharpness, and diagnostic confidence. Image noise and signal-to-noise ratio were quantified.

RESULTS

Diagnostic image quality was achieved for all scans on 101 patients. The 1024 reconstruction demonstrated increased image noise (20.2 ± 4.0 vs 17.2 ± 3.8, P < 0.001) and a worse noise rating (1.98 ± 0.63 vs 1.75 ± 0.61, P < 0.001) but performed significantly better than conventional 512 matrix with fewer artifacts (1.37 ± 0.43 vs 1.50 ± 0.48, P < 0.001), better contrast (1.50 ± 0.56 vs 1.62 ± 0.57, P < 0.001), small detail detection (1.06 ± 0.19 vs 2.02 ± 0.22, P < 0.001), lesion conspicuity (1.08 ± 0.23 vs 2.02 ± 0.24, P < 0.001), sharpness (1.09 ± 0.24 vs 2.02 ± 0.28, P < 0.001), and overall diagnostic confidence (1.09 ± 0.25 vs 1.18 ± 0.34, P < 0.001).

CONCLUSIONS

Ultrahigh-resolution computed tomography enabled a higher reconstruction matrix and improved image quality compared with conventional matrix reconstruction, with a minor increase in noise.

Tree-in-Bud Pattern of Pulmonary Tuberculosis on Thin-Section CT: Pathological Implications

The “tree-in-bud-pattern” of images on thin-section lung CT is defined by centrilobular branching structures that resemble a budding tree. We investigated the pathological basis of the tree-in-bud lesion by reviewing the pathological specimens of bronchograms of normal lungs and contract radiographs of the post-mortem lungs manifesting active pulmonary tuberculosis. The tree portion corresponds to the intralobular inflammatory bronchiole, while the bud portion represents filling of inflammatory substances within alveolar ducts, which are larger than the corresponding bronchioles. Inflammatory bronchiole per se represents the “tree” (stem) and inflammatory alveolar ducts constitute the “buds” or clubbing. “Clusters of micronodules”, seen on 7-mm thick post-mortem radiographs with tuberculosis proved to be clusters of tree-in-bud lesions within the three-dimensional space of secondary pulmonary lobule based on radiological/pathological correlation. None of the post-mortem lung specimens showed findings of lung parenchymal lymphatics involvement.

Pulmonary measles disease: old and new imaging tools

BACKGROUND

Measles virus can cause lower respiratory tract infection, so that chest radiography is necessary to investigate lung involvement in patients with respiratory distress.

PURPOSE

To assess measles pneumonia imaging during the measles outbreak occurred in 2016-2017 in Italy.

MATERIAL AND METHODS

We retrospectively observed adult patients with a serological diagnosis of measles, who underwent chest-X rays for suspected pneumonia. If a normal radiography resulted, the patient underwent unenhanced CT. A CT post processing software package was used for an additional quantitative lung and airway involvement analysis .

RESULTS

Among 290 patients affected by measles, 150 underwent chest-X ray. Traditional imaging allowed the pneumonia diagnosis in 114 patients (76%). The most frequent abnormality at chest X-rays was bronchial wall thickening, observed in 88.5% of the cases; radiological findings are faint in the 25% of the cases (29/114 patients). In nine subjects with a normal chest X-ray, unenhanced CT with a quantitative analysis was performed, and depicted features consistent with constrictive bronchiolitis.

CONCLUSION

Measles may produce bronchiolitis and pneumonia. In the cases in which involvement of pulmonary parenchyma is not sufficient to result in radiological abnormalities, CT used with a dedicated postprocessing software package, provides an accurate lungs and airways analysis, also determining the percentage of lung involvement.

The imaging spectrum of pulmonary tuberculosis

Tuberculosis has still an important impact on public health because it is an important cause of death, particularly in developing countries. On the other hand recent studies have shown that tuberculosis is again becoming concentrated in big cities of Western Europe, especially among immigrants, drug addicts, poor people, and the homeless, despite progress in reducing national rates of the disease. Diagnostic imaging is challenging for radiologists because signs of tuberculosis may easily mimic other diseases such as neoplasms or sarcoidosis. Clinical signs and symptoms in affected adults can be non-specific and a high level of pre-test clinical suspicion based on history is fundamental in the diagnostic work-up. Impact of tuberculosis in the world is extremely important considering the high incidence estimated during 2011 that was 8.7 million cases. This article gives a review of imaging patterns of chest tuberculosis as may be detected on conventional radiography and computerized tomography (CT). The main aim is to improve radiologist's familiarity with the spectrum of imaging features of this disease and facilitate timely diagnosis. Furthermore, we consider the emerging role of alternative methods of imaging, such as magnetic resonance imaging (MRI), that can be helpful and highly accurate for a better definition of some signs of tuberculosis.

A practical approach to high-resolution CT of diffuse lung disease

Diffuse lung disease presents a variety of high-resolution CT findings reflecting its complex pathology, and provides diagnostic challenge to radiologists. Frequent modification of detailed pathological classification makes it difficult to keep up with the latest understanding. In this review, we describe a practical approach to high-resolution CT diagnosis of diffuse lung disease, emphasizing (1) analysis of "distribution" of the abnormalities, (2) interpretation of "pattern" in relation to distribution, (3) utilization of associated imaging findings and clinical information, and (4) chronicity of the findings. This practical approach will help radiologists establish a way to interpret high-resolution CT, leading to pin-point diagnosis or narrower differential diagnoses of diffuse lung diseases.

Classification of Centrilobular Emphysema Based on CT-Pathologic Correlations

Introduction:

Centrilobular emphysema (CLE) is recognized as low attenuation areas (LAA) with centrilobular distribution on high-resolution computed tomography. The LAA often exhibit a variety of shape or sharpness of border. This study was performed to elucidate the relationship between morphological features of LAA and pathological findings in CLE.

Materials and Methods:

The inflated-fixed lungs from 50 patients with CLE (42 males, 8 females; 14 operated, 36 autopsied) were examined by a method of CT-pathologic correlations that consisted of three steps. The first, CT images of the sliced lungs of the inflated-fixed lung specimens were examined on the shape and the peripheral border of each LAA. The second, the sliced lungs were radiographed in contact with high magnification. The third, the surface of the sliced lungs was observed by using stereomicroscopy. The views at low magnification of stereomicroscope were compared with the radiographs and the CT images of the same sample.

Results:

Using CT-pathologic correlations, LAAs of CLE were classified into three types as follows; round or oval shape with well-defined border (Type A), polygonal or irregular shape with ill-defined border and less than 5 mm in diameter (Type B), and irregular shape with ill-defined border and 5 mm or over in diameter (Type C). Type A, Type B and Type C LAA were mainly related to dilatation of bronchioles, destruction of proximal part of alveolar ducts, and destruction of distal part of alveolar ducts, respectively. Type A, Type B and Type C were dominant LAA in 5 (10%), 29 (58%) and 12 (24%) patients, respectively. However, remained 4 patients (8%) did not show dominant LAA type.

Conclusion:

Morphological features of LAA in CLE may depend on dilatation or destruction of certain parts of the secondary lobule. Type B LAA was the commonest type in CLE.

Lung infections: the radiologist's perspective

Imaging plays a key role in lung infections. A CT scan must be carried out when there is a strong clinical suspicion of pneumonia that is accompanied by normal, ambiguous, or nonspecific radiography, a scenario that occurs most commonly in immunocompromised patients. CT allows clinicians to detect associated abnormalities or an underlying condition and it can guide bronchoalveolar lavage or a percutaneous or transbronchial lung biopsy. An organism can vary in how it is expressed depending on the extent to which the patient is immunocompromised. This is seen in tuberculosis in patients with AIDS. The infective agents vary with the type of immune deficiency and some infections can quickly become life-threatening. Clinicians should be aware of the complex radiological spectrum of pulmonary aspergillosis, given that this diagnosis must be considered in specific settings.

Imaging of pulmonary emphysema: a pictorial review

The term 'emphysema' is generally used in a morphological sense, and therefore imaging modalities have an important role in diagnosing this disease. In particular, high resolution computed tomography (HRCT) is a reliable tool for demonstrating the pathology of emphysema, even in subtle changes within secondary pulmonary lobules. Generally, pulmonary emphysema is classified into three types related to the lobular anatomy: centrilobular emphysema, panlobular emphysema, and paraseptal emphysema. In this pictorial review, we discuss the radiological--pathological correlation in each type of pulmonary emphysema. HRCT of early centrilobular emphysema shows an evenly distributed centrilobular tiny areas of low attenuation with ill-defined borders. With enlargement of the dilated airspace, the surrounding lung parenchyma is compressed, which enables observation of a clear border between the emphysematous area and the normal lung. Because the disease progresses from the centrilobular portion, normal lung parenchyma in the perilobular portion tends to be preserved, even in a case of far-advanced pulmonary emphysema. In panlobular emphysema, HRCT shows either panlobular low attenuation or ill-defined diffuse low attenuation of the lung. Paraseptal emphysema is characterized by subpleural well-defined cystic spaces. Recent topics related to imaging of pulmonary emphysema will also be discussed, including morphometry of the airway in cases of chronic obstructive pulmonary disease, combined pulmonary fibrosis and pulmonary emphysema, and bronchogenic carcinoma associated with bullous lung disease.

High resolution chest CT in patients with pulmonary tuberculosis: Characteristic findings before and after antituberculous therapy

OBJECTIVE

The purpose of this study was (a) to describe HRCT findings for pulmonary tuberculosis before and after treatment, and (b) to evaluate the possible use of HRCT to assess disease activity.

PATIENTS AND METHODS

We prospectively studied 52 patients with newly diagnosed pulmonary tuberculosis that was proven bacteriologically. HRCT scans were performed before and after treatment.

RESULTS

Micronodules, nodules, tree-in-bud appearance, consolidation, and cavities were the most common HRCT findings seen in active pulmonary tuberculosis. The disappearance of tree-in-bud appearance, pleural effusion and the presence of fibrotic change appear to be indications of the effectiveness of treatment. HRCT can differentiate old fibrotic lesions from newly active tuberculous lesions.

CONCLUSIONS

HRCT may be helpful in the diagnosis of pulmonary tuberculosis and may be useful in the assessment of the efficacy of anti-tuberculous treatment.

[Radiologic-anatomic correlation of thoracic vertebrae and rib shadows in chest digital radiograph]

The purpose of this study was to provide an introduction to parsing the radiologic appearance of thoracic vertebrae and ribs. In the study, the radiologic-anatomic correlation technique was applied to promote further understanding of normal chest radiographs. The thoracic vertebrae and ribs of chest radiographs were compared with each macroscopic radiologic and computed tomography (CT) image. The rib parsed the linear shadow of the body of the rib. The macroscopic and radiologic images of thoracic vertebrae and ribs were evaluated to explain their normal radiologic findings. The results of such correlation were summarized as follows: 1) The lamina of the vertebral arch was visualized due to anterior rotation of the upper thoracic vertebrae. 2) The density ratio of the thoracic-vertebrae shadow was almost the same in the vertebral body and vertebral arch. 3) The linear shadow superimposed on the rib corresponded to the inferior margin of the rib. The radiologic-anatomic correlation technique was useful to evaluate normal radiologic findings, and the study was useful to radiological technologists.

Thin-section CT of the secondary pulmonary lobule: anatomy and the image--the 2004 Fleischner lecture

The secondary pulmonary lobule is a fundamental unit of lung structure, and it reproduces the lung in miniature. Airways, pulmonary arteries, veins, lymphatics, and the lung interstitium are all represented at the level of the secondary lobule. Several of these components of the secondary lobule are normally visible on thin-section computed tomographic (CT) scans of the lung. The recognition of lung abnormalities relative to the structures of the secondary lobule is fundamental to the interpretation of thin-section CT scans. Pathologic alterations in secondary lobular anatomy visible on thin-section CT scans include interlobular septal thickening and diseases with peripheral lobular distribution, centrilobular abnormalities, and panlobular abnormalities. The differential diagnosis of lobular abnormalities is based on comparisons between lobular anatomy and lung pathology.

Specific high-resolution computed tomography findings associated with sputum smear-positive pulmonary tuberculosis

OBJECTIVES

This study aimed to evaluate whether high-resolution computed tomography (HRCT) could predict the results of a sputum smear in patients with active pulmonary tuberculosis.

METHODS

Forty-eight patients with active pulmonary tuberculosis were divided into 2 groups: sputum smear-positive (n = 25) and -negative (n = 23). The HRCT findings were retrospectively reviewed, focusing on the presence or absence of features previously reported to indicate active pulmonary tuberculosis, including ground-glass opacity, cavitation, centrilobular opacity, and air space consolidation.

RESULTS

Although air space consolidation was the least common feature overall, it occurred significantly more frequently in the smear-positive group than in the smear-negative group. This feature also had the highest specificity and positive predictive value. Cavitation and ground-glass opacity also occurred significantly more frequently in the smear-positive group. The frequency of centrilobular opacity did not differ between the 2 groups.

CONCLUSIONS

The present study suggested that the HRCT findings of air space consolidation, cavitation, and ground-glass opacity are significantly associated with smear-positive pulmonary tuberculosis.

Community-acquired and nosocomial pneumonia

Pneumonia is one of the leading causes of morbidity, hospitalization, and mortality in both industrialized and developing countries. In particular, pulmonary infections acquired in the community, and pneumonias arising in the hospital setting, represent a major medical and economic problem and thus a continuous challenge to health care. For the radiologist, it is important to understand that community-acquired pneumonia (CAP) and nosocomial pneumonia (NP) share a number of characteristics, but should, in many respects be regarded as separate entities. CAP and NP arise in different populations, host different spectra of causative pathogens, and pose different challenges to both the clinician and the radiologist. CAP is generally seen in outpatients, is most frequently caused by Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, and Chlamydia, and its radiologic diagnosis is relatively straightforward. NP, in contrast, develops in the hospital setting, is commonly caused by gram-negative bacteria, and may generate substantial problems for the radiologist. Overall, both for CAP and NP, imaging is an integral component of the diagnosis, important for classification and differential diagnosis, and helpful for follow-up.

Tuberculose pulmonar: achados na tomografia computadorizada de alta resolução do tórax em pacientes com doença em atividade comprovada bacteriologicamente

Objetivo: Descrever os achados em pacientes com tuberculose pulmonar em atividade na tomografia computadorizada de alta resolução e o padrão de distribuição das lesões pelo parênquima pulmonar. Casuística e método: Foram analisadas retrospectivamente as tomografias de alta resolução de 42 pacientes com diagnóstico bacteriológico de tuberculose pulmonar ou forte suspeita clínica, com posterior confirmação bacteriológica. Resultados: Os principais sinais sugestivos de atividade encontrados foram nódulos do espaço aéreo (83%), nódulos centrolobulares (74%), aspecto de árvore em brotamento (67%), cavitações (67%), espessamento das paredes brônquicas (55%), consolidações (48%), opacidade em vidro fosco (21%), e espessamento do interstício pulmonar (9%). Conclusão: A tomografia computadorizada de alta resolução do tórax pode sugerir fortemente atividade da doença, sendo particularmente útil nos pacientes com baciloscopias negativas e/ou radiografias indeterminadas, permitindo a instituição de tratamento adequado, antes mesmo do crescimento da micobactéria em meio de cultura.

Evaluation of pulmonary infiltrates in critically ill patients with cancer and marrow transplant

Pulmonary infiltrates in critically ill patients with cancer or marrow transplant can be evaluated by the differential diagnosis presented at the beginning of this article. The patient's quantitative immune system dysfunction, epidemiologic history and chest radiographic findings (pattern, rapidity, and time of onset) will help focus the differential diagnosis. In this patient population, however, common diagnoses can have atypical presentations, unusual diagnoses do occur, and more than one process may be responsible for a patient's infiltrates. Early bronchoscopy to rule out infection is the focus of diagnostic testing. Surgical lung biopsy in this patient population has a low yield.

Structural basis for pulmonary functional imaging

An understanding of fine normal lung morphology is important for effective pulmonary functional imaging. The lung specimens must be inflated. These include (a) unfixed, inflated lung specimen, (b) formaldehyde fixed lung specimen, (c) fixed, inflated dry lung specimen, and (d) histology specimen. Photography, magnified view, radiograph, computed tomography, and histology of these specimens are demonstrated. From a standpoint of diagnostic imaging, the main normal lung structures consist of airways (bronchi and bronchioles), alveoli, pulmonary vessels, secondary pulmonary lobules, and subpleural pulmonary lymphatic channels. This review summarizes fine radiologic normal lung morphology as an aid to effective pulmonary functional imaging.

Pulmonary tuberculosis with unusual cystic change in an immunocompromised host

We present a rare case of upper zone cystic change of the lung with disseminated tuberculosis of a non-smoking 30-year-old immunocompromised male. He suffered from repeated pneumothorax. The basic pathological feature of video-assisted thoracoscopic lung biopsy revealed granulomatous involvement in the respiratory bronchioles with poorly developed epithelioid cells and disruption of elastic fibers. Electron microscopy demonstrated a decrease in elastic fibers and disruption of the epithelial basement membrane of the respiratory bronchiole and no Langerhans cells in the lesion. Autopsy of the lung revealed centroacinar distribution of multiple cystic lesions in the bilateral upper lobe. Almost all cystic walls showed loss of elastic fibers and cysts frequently involved the respiratory and terminal bronchioles, alveolar ducts and, occasionally, alveoli. Some larger cystic lesions revealed communication to the bronchi. The cystic changes in this case of pulmonary tuberculosis may be caused by a check-valve mechanism due to granulomatous involvement of the bronchioles and also by excavation of caseous necrotic material by draining bronchi.

Radiology of pneumonia

Chest radiography is the imaging technique of choice in evaluating patients with suspected pneumonia because of its low radiation dose, low cost, and wide accessibility. In daily practice, radiographs are used to confirm the clinical diagnosis of pneumonia, characterize the extent and severity of disease, search for complications such as empyema, monitor the response to therapy, and examine for possible alternative or additional diagnoses. Although CT scan has no defined role in the routine assessment of patients with either community-acquired or nosocomial pneumonias, its advantages of superior contrast resolution and cross-sectional display can often be helpful in the analysis of complex cases, particularly when radiographic evidence of associated central obstruction, cavitation, lymphadenopathy, or empyema is equivocal. In the immunocompromised patient population, high-resolution CT has been shown to be more sensitive than plain film radiography in the early detection of pulmonary infections.

Multinodular disease: anatomic localization at thin-section CT--multireader evaluation of a simple algorithm

PURPOSE

To evaluate the interobserver variability and accuracy of an algorithm for anatomic localization of small nodules evident on thin-section computed tomographic (CT) images of the lungs.

MATERIALS AND METHODS

Four experienced chest radiologists independently evaluated thin-section CT images in 58 patients by using an algorithm and a standard score sheet. Nodules were placed into four possible anatomic locations or categories: perilymphatic, random, associated with small airways disease, or centrilobular. Algorithm accuracy was assessed by comparing the localization by the observers to that expected for each specific disease in the study group on the basis of reports in the literature. Interobserver variability was assessed by placing cases into one of three groups: (a) complete concordance, (b) triple concordance, and (c) discordant.

RESULTS

All observers agreed in 79% (46 of 58) of the cases with regard to nodule localization; three of the four concurred in an additional 17% (10 of 58). The observers were correct in 218 (94%) of 232 localizations in the 58 cases. There were no apparent differences in the number of either discordant or incorrect localizations between the observers. The most noteworthy source of error and of disagreement between observers was the confusion of perilymphatic and small airways disease-associated nodules in a small number of cases.

CONCLUSION

The proposed algorithm is reproducible and accurate in the majority of cases and facilitates nodule localization at thin-section CT.

Pulmonary tuberculosis treated with directly observed therapy: serial changes in lung structure and function

OBJECTIVES

(1) To correlate structure (CT) with function in pulmonary tuberculosis (TB), and (2) to describe the evolution of structural and functional abnormalities when pulmonary TB is treated with directly observed therapy.

SUBJECTS AND METHODS

Twenty-five patients with drug-susceptible pulmonary TB, 15 cavitary and 10 noncavitary, were studied prospectively. Conventional CT and pulmonary function testing (spirometry, diffusing capacity, and arterial blood gases) were performed at baseline, and after 1 and 6 months of directly observed therapy.

RESULTS

All but one patient with noncavitary miliary TB had CT evidence of endobronchial disease, and all patients with cavitary disease had coexistent reduced lung attenuation, the latter presumably a result of gas trapping, hypoxic vasoconstriction, and vascular injury. Functional impairment was minimal and in proportion to the number of diseased segments and cavitary volume. Bronchiectasis was significantly more likely to complicate cavitary than noncavitary disease (64 vs 11%; p<0.05).

CONCLUSIONS

CT findings correlate well with function in pulmonary TB. Physiologic data were consistent with the concept that pulmonary TB is an endobronchial disease that causes parallel reductions in ventilation and perfusion. This concurrent involvement of both airways and contiguous pulmonary blood supply offers an explanation for the minimal respiratory limitation experienced by these patients despite often extensive lung disease. Supervised therapy of drug-susceptible disease results in minimal structural and functional residua.

Computed tomography features of lung parenchymal changes in pulmonary tuberculosis

Twenty-five patients with active pulmonary tuberculosis were prospectively studied with CT. Three major parenchymal patterns were noted. The nodular opacities pattern was seen in all cases. Confluent consolidation was seen in 37% of patients and consolidation with associated loss of volume (CWALV) was seen in 69% of patients. High-resolution CT (HRCT) features of bronchogenic spread included (i) a centrilobular nodule or a branching linear structure (92.3%); (ii) bronchial wall thickening (61.5%); (iii) a 'tree in bud' appearance (92.3%); and (iv) poorly marginated 5-8 mm nodules (61.5%). Most of the patterns showed satellite lesions in the form of small nodules or peripheral areas of increased attenuation. Cavitation was most common in CWALV lesions. Bronchiectasis was a common accompaniment (81.3%), and its occurrence paralleled the distribution of parenchymal lesions. Associated pleural thickening was noted in half the cases. To conclude, distinctive parenchymal changes were noted with CT in cases of pulmonary tuberculosis, which may suggest the diagnosis in the appropriate clinical setting.

High resolution chest CT in tuberculosis: evolutive patterns and signs of activity

PURPOSE

The purpose of our study was to determine evolutive patterns and signs of active tuberculosis on high resolution CT (HRCT) scans.

METHOD

We followed up over 15 months 27 patients with postprimary pulmonary tuberculosis that was proven bacteriologically. CT scans were performed before, during, and after 6 months of anti-tuberculosis treatment. Both 10-mm-thick sections and 1.5-mm-thick HRCT scans were performed.

RESULTS

Ground-glass pattern was noticed 26 times, 9 times after 2 month treatment and only 2 times after 6 month treatment. Among these two patients, one did not undergo his treatment properly and the other one had an additional bacterial infection. Centrilobular nodules (n = 17) and poorly marginated nodules (n = 21) were present only before treatment. Reticular pattern (intralobular and septal thickening), interstitial nodules, and fibrosis were seen both before and after treatment. Ground-glass pattern, poorly marginated nodules, and infiltrates as well as centrilobular nodules were related to an active infection.

CONCLUSION

This HRCT may be helpful to demonstrate activity in patients suspected of having tuberculosis and to assess antituberculous treatment efficiency.

Application of whole-mount section of lung specimen in study of radiologic-pathologic correlations

We evaluated the usefulness of the whole-mount section of the inflated-fixed lung specimen in the study of radiologic-pathologic correlations. Altogether, 24 resected fresh lobe specimens with 1.5- to 3.0-cm solitary pulmonary carcinomas or tuberculomas were inflated with air, intrabronchially fixed by infusing Heitzman's solution, and finally cut into 10- to 15-micron-thick whole-mount sections for the histopathological examination. All 24 inflated-fixed lobes were satisfactorily soft as sponge, sufficiently springy, and kept their original shape. All whole-mount sections clearly presented the complete morphological features of the whole lobes, and could be directly observed by the naked eye and examined under microscopy. The use of the whole-mount section of the lung specimen may facilitate precisely and effectively the studies of the radiologic-pathologic correlations.

Tree-in-bud pattern: frequency and significance on thin section CT

PURPOSE

Our goal was to describe those diseases of the airways that manifest the tree-in-bud (TIB) pattern on CT scan and to establish a differential diagnosis for this CT scan finding.

METHOD

We prospectively collected cases with the TIB pattern on CT and reviewed the scans of patients with histories pertaining to small airway disease. CT scans were performed at 1 to 3 mm collimation.

RESULTS

Twenty-six of 27 cases with the TIB pattern had associated bronchiectasis or proximal airway wall thickening. One case with normal proximal airways had an acute aspiration. In addition, we reviewed 141 scans of patients with emphysema, respiratory bronchiolitis (RB), bronchiolitis obliterans (BO), bronchiolitis obliterans organizing pneumonia (BOOP), extrinsic allergic alveolitis (EAA), bronchiectasis, bronchitis, and pneumonia. Of the CT scans with bronchiectasis, 25.6% had TIB, and 17.6% of CT scans with acute infectious bronchitis or pneumonia had this pattern. None of the patients with emphysema, BO, BOOP, EAA, or RB had this pattern.

CONCLUSION

The TIB pattern on CT scan is mostly associated with pulmonary infections that commonly involve the large airways. This pattern was present in 17.6% of cases with acute bronchitis or pneumonia and 25.6% of cases with bronchiectasis.

Identification and evaluation of centrilobular opacities on high-resolution CT

Abnormal findings on high-resolution CT that are localized to the centrilobular region imply primary disease of the small airways or primary peribronchiolar or perivascular pathology. We review methods of localizing abnormal opacity to the centrilobular region and discuss differential diagnostic considerations for centrilobular disease. Straightforward ways to differentiate between primary small-airways disease and peribronchiolar or perivascular conditions are also emphasized. Although perilymphatic disorders can also be associated with centrilobular opacities, these conditions have a distinctive appearance that warrants separate categorization; distinguishing characteristics of perilymphatic disorders with respect to the centrilobular conditions are discussed.

CT of pulmonary metastases with pathological correlation

CT, including high-resolution CT, has become an essential means of imaging to evaluate pulmonary metastases. The underlying pathological processes of pulmonary metastases can be observed well on CT images, but they are not always specific. Several important CT features correlate with histopathological findings: (1) margin of nodule; (2) hemorrhage accompanying a metastatic nodule; (3) calcification; (4) cavitation; (5) sterilized metastasis; (6) small metastatic nodules in the lobules; (7) lymphangitic carcinomatosis; (8) tumor emboli; and (9) pleural metastases. For reasonable use of CT in pulmonary metastases, these various CT manifestations and their limitations must be understood.

CT of pulmonary tuberculosis

CT scans in patients with primary tuberculosis commonly show lymphohematogenous spread of the disease, whereas those of postprimary (reactivation) tuberculosis commonly show bronchogenic spread. High-resolution CT (HCRT) is extremely helpful in understanding pathomorphological changes, mode of spread of the disease, and sequential morphological change after antituberculous chemotherapy, and possibly in diagnosing activity of the disease. Centrilobular 2- to 4-mm nodules or branching linear lesions representing intrabronchiolar and peribronchiolar caseation necrosis are the most common findings of early bronchogenic spread of tuberculosis. The 2- to 4-mm centrilobular nodules may coalesce to form 5- to 8-mm nodules or lobular consolidation. Cavitation usually begins at the central portion of a lobule around the bronchioles. Resolution of the tuberculous lesions occurs with antituberculous chemotherapy, resulting in varying degrees of fibrosis, bronchovascular distortion, emphysema, and bronchiectasis. HRCT may show both paracicatricial irregular emphysema and lobular emphysema. CT findings of early miliary dissemination commonly include ground-glass opacification with barely discernible nodules that show discrete miliary nodules thereafter. CT also is useful in the evaluation of long-standing destructive pulmonary lesions and tracheobronchial tuberculosis.

High-resolution computed tomography and diffuse lung disease

Diffuse lung diseases are often difficult to characterize on chest radiographs. It has been a challenge for the radiologist to obtain useful diagnostic information from these studies and then communicate that information to the clinician. Robert Heitzman recognized the utility of understanding lung diseases in terms of their effect on the structures of the secondary lobule. Unfortunately, he needed inflated lung specimens to reliably visualize the small structures within the secondary lobule. Such specimens are no longer needed. High-resolution computed tomography (HRCT) scans of the lung provide an excellent representation of the secondary lobule. In this monograph, we have attempted to explain the normal anatomy of the secondary lobule, the patterns of abnormality, the technique for performing HRCT, and an approach to diffuse lung disease. In the second half of the article we have classified the more common diffuse lung diseases according to the dominant pathologic change: high versus low attenuation.

High-resolution computed tomography of the lung

High-resolution computed tomography (HRCT) and thin-section CT are techniques that are particularly suited for evaluation of the pulmonary parenchyma. These techniques have been found useful in the assessment of bronchiectasis and solitary pulmonary nodules. HRCT offers promise in evaluation of diffuse and focal pulmonary parenchymal disease. The principles and applications of HRCT of the lung are reviewed.