The secondary pulmonary lobule: a practical concept for interpretation of chest radiographs. II. Application of the anatomic concept to an understanding of roentgen pattern in disease states

Chest computed tomography (CT) findings and semiquantitative scoring of 60 patients with coronavirus disease 2019 (COVID-19): A retrospective imaging analysis combining anatomy and pathology

In this study, we ascertained the chest CT data of 60 patients admitted to 3 hospitals in Chongqing with confirmed COVID-19. We conducted anatomical and pathological analyses to elucidate the possible reasons for the distribution, morphology, and characteristics of COVID-19 in chest CT. We also shared a semiquantitative scoring of affected lung segments, which was recommended by our local medical association. This scoring system was applied to quantify the severity of the disease. The most frequent imaging findings of COVID-19 were subpleural ground glass opacities and consolidation; there was a significant difference in semiquantitative scores between the early, progressive, and severe stages of the disease. We conclude that the chest CT findings of COVID-19 showed certain characteristics because of the anatomical features of the human body and pathological changes caused by the virus. Therefore, chest CT is a valuable tool for facilitating the diagnosis of COVID-19 and semiquantitative scoring of affected lung segments may further elucidate diagnosis and assessment of disease severity. This will assist healthcare workers in diagnosing COVID-19 and assessing disease severity, facilitate the selection of appropriate treatment options, which is important for reducing the spread of the virus, saving lives, and controlling the pandemic.

Computed tomography: revolutionizing the practice of medicine for 40 years

Computed tomography (CT) has had a profound effect on the practice of medicine. Both the spectrum of clinical applications and the role that CT has played in enhancing the depth of our understanding of disease have been profound. Although almost 90 000 articles on CT have been published in peer-reviewed journals over the past 40 years, fewer than 5% of these have been published in Radiology. Nevertheless, these almost 4000 articles have provided a basis for many important medical advances. By enabling a deepened understanding of anatomy, physiology, and pathology, CT has facilitated key advances in the detection and management of disease. This article celebrates this breadth of scientific discovery and development by examining the impact that CT has had on the diagnosis, characterization, and management of a sampling of major health challenges, including stroke, vascular diseases, cancer, trauma, acute abdominal pain, and diffuse lung diseases, as related to key technical advances in CT and manifested in Radiology.

A comparative study of honeycombing on high resolution computed tomography with histologic lung remodeling in explants with usual interstitial pneumonia

BACKGROUND

There is little information comparing high-resolution computed tomography (HRCT) findings in UIP with different components that make up remodeling histologically.

DESIGN

We compared histologic features with HRCT scans from 69 explants with UIP. The extent of 7 histologic features were semi-quantitated: respiratory-lined cysts, bronchiolectasis, pulmonary interstitial emphysema (PIE), lobular remodeling, areas resembling non-specific interstitial pneumonia (NSIP), desquamative interstitial pneumonia (DIP)-like pattern, and mucus pooling within cysts extending into surrounding parenchyma. Subpleural cystic spaces and areas of lobular remodeling were measured morphometrically. Histologic features were compared to three findings on HRCT: diagnostic pattern (UIP, probable UIP, or inconsistent with UIP pattern), degree of honeycombing, and degree of ground-glass opacities.

RESULTS

Histologically, respiratory-lined cysts were observed in 78%, bronchiolectasis in 83%, interstitial emphysema in 22%, lobular remodeling in 96%, NSIP-like areas in 87%, DIP-like reaction in 10%, and mucin extravasation in 78%. Morphometrically, cysts of PIE measured 6.2±2.9 mm, respiratory-lined cysts 3.5±2.4 mm, and bronchiolectatic cysts 3.3±1.5 mm. Remodeled lobules measured 3.6±1.1 mm. UIP pattern on CT correlated strongly with histologic extent of bronchiolectasis (p=0.001). HRCT honeycombing showed a positive correlation with histologic bronchiolectasis (p=0.001) and respiratory-lined cysts (p=0.001). GGO was positively associated with NSIP-like areas (p=0.02) and extravasated mucus (p=0.05).

CONCLUSIONS

HRCT findings typical of UIP and HRCT honeycombing correlate best with bronchiolectasis histologically. NSIP pattern is common, and is associated with CT finding of GGO.

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.

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.

Topographic basis of bimodal ventilation-perfusion distributions during bronchoconstriction in sheep

The distribution of ventilation-perfusion (VA/Q) ratios during bronchoconstriction measured with the multiple inert gases elimination technique is frequently bimodal. However, the topographic basis and the cause of that bimodality remain unknown. In this article, regional VA/Q is quantified by three-dimensional positron emission tomography (PET) imaging of methacholine-induced bronchoconstriction in sheep. Regional VA/Q ratios were calculated from the imaged kinetics of intravenously injected 13NN-saline bolus, assembled into global VA/Q distributions, and used to estimate gas exchange. During bronchoconstriction, large regions with impaired tracer washout were observed adjacent to regions of normal ventilation. PET-derived VA/Q distributions during bronchoconstriction were consistently bimodal, with areas of low VA/Q receiving a large fraction of Q. The standard deviation of the VA/Q distribution was 38% lower if small-scale (subresolution) heterogeneity (< 2.2 cm3) was ignored. Arterial blood gases predicted from PET data correlated well with measured values for Pa(O2) (r2= 0.91, p < 0.01) and Pa(CO2) (r2= 0.90, p < 0.01). We conclude that the bimodality of VA/Q distributions in bronchoconstriction reflects the involvement of large contiguous regions of hypoventilation with substantial subresolution intraregional VA/Q heterogeneity. Assessment of the subresolution VA/Q heterogeneity is therefore essential to accurately quantify global gas exchange impairment during bronchoconstriction.

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.

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.

Pneumonia. Pearls for interpreting patients' radiographs

The chest radiograph can detect pneumonia, but laboratory evaluation is needed to determine the specific causative organism. However, before these results become available, a presumptive diagnosis can be made with the help of chest radiography. A lobar pattern on radiography is usually produced by pneumococcal and Klebsiella infections. A lobular (bronchopneumonia) pattern may be produced by Staphylococcus, gram-negative organisms, and anaerobes. An interstitial pattern results from viral, Mycoplasma, and Pneumocystis carinii infections. Mixed patterns may also occur. There is great variation in the presentation of each infection. However, pertinent clinical information, epidemiologic factors, and associated radiographic findings (eg, adenopathy, pleural effusion, cavitation) are helpful in further limiting diagnostic possibilities.