Ground-glass attenuation in nodular bronchioloalveolar carcinoma: CT patterns and prognostic value

Aerogenous Metastasis and Spread Through the Air Spaces - Distinct Entities or Spectrum of the Same Process?

Clinicopathological and imaging studies indicate that metastatic spread of cancer cells through the airways may occur in primary lung cancer. The term aerogenous metastasis was been proposed years before the concept of spread through the airspaces (STAS) was introduced in the current World Health Organization classification. The pathogenesis of STAS has not been fully elucidated. The current definition of STAS is controversial and limited to early stage adenocarcinomas. In this article, existing knowledge on the pathogenesis, histology, imaging findings, and clinical and prognostic significance of these 2 entities is presented.

CT Halo sign: A systematic review

PURPOSE

The CT Halo sign or Halo sign (HS) refers to ground-glass opacity surrounding a nodule or mass in the lung parenchyma. We conducted a systematic review to find the etiological associations of HS. We also evaluated the diagnostic performances of HS for invasive fungal infections (IFI) in immunosuppressed patients.

METHOD

The systematic review was conducted as per PRISMA guidelines. We searched the PubMed and EMBASE database till June 2018 without any restrictions. Only case reports, case series and original articles published in English language were included. A database created from the electronic searches was compiled and subsequent analysis was done. [PROSPERO registration: CRD42018094739] RESULTS: 168 studies were eligible, which included 51 case reports, 15 prospective studies, 102 retrospective studies. A total of 1977 patients (out of 6371) with HS were identified with age range between <1year-94years. The most common diagnosis in the immunosuppressed, mixed, immunocompetent and not specified groups were IFI (86.9 %, n = 1194), Cryptococcosis (51.6 %, n = 124), Cryptococcosis (40 %, n = 20) and lung neoplasms (81.8 %, n = 36) respectively. 14 studies (11 retrospective, 3 prospective) were included in quantitative analysis. The pooled sensitivity(sn), specificity(sp) and odd's ratio (OR) of HS for diagnosing IFI were 50.4 %, 91 % and 6.61 respectively. Also, HS could not reliably differentiate IPA from mucormycosis in the pooled analysis.

CONCLUSIONS

HS can be seen in a large number of diverse conditions both in immunosuppressed and immunocompetent population. In immunosuppressed patients HS is specific for IFI but cannot rule it out. Additionally, it cannot reliably distinguish between IPA and mucormycosis.

Can MRI contribute to pulmonary nodule analysis?

BACKGROUND

There is no accurate method distinguishing different types of pulmonary nodules.

PURPOSE

To investigate whether multiparametric 3T MRI biomarkers can distinguish malignant from benign pulmonary nodules, differentiate different types of neoplasms, and compare MRI-derived measurements with values from commonly used noninvasive imaging modalities.

STUDY TYPE

Prospective.

SUBJECTS

Sixty-eight adults with pulmonary nodules undergoing resection.

SEQUENCES

Respiratory triggered diffusion-weighted imaging (DWI), periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) fat saturated T₂ -weighted imaging, T₁ -weighted 3D volumetric interpolated breath-hold examination (VIBE) using CAIPIRINHA (controlled aliasing in parallel imaging results in a higher acceleration).

ASSESSMENT/STATISTICS

Apparent diffusion coefficient (ADC), T₁ , T₂ , T₁ and T₂ normalized to muscle (T₁ /M and T₂ /M), and dynamic contrast enhancement (DCE) values were compared with histology to determine whether they could distinguish malignant from benign nodules and discern primary from secondary malignancies using logistic regression. Predictability of primary neoplasm types was assessed using two-sample t-tests. MRI values were compared with positron emission tomography / computed tomography (PET/CT) to examine if they correlated with standardized uptake value (SUV) or CT Hounsfield unit (HU). Intra- and interreader agreements were assessed using intraclass correlations.

RESULTS

Forty-nine of 74 nodules were malignant. There was a significant association between ADC and malignancy (odds ratio 4.47, P < 0.05). ADC ≥1.3 μm² /ms predicted malignancy. ADC, T₁ , and T₂ together predicted malignancy (P = 0.003). No MRI parameter distinguished primary from metastatic neoplasms. T₂ predicted PET positivity (P = 0.016). T₂ and T₁ /M correlated with SUV (P < 0.05). Of 18 PET-negative malignant nodules, 12 (67%) had an ADC ≥1.3 μm² /ms. With the exception of T₂ , all noncontrast MRI parameters distinguished adenocarcinomas from carcinoid tumors (P < 0.05). T₁ , T₂ , T₁ /M, and T₂ /M correlated with HU and therefore can predict nodule density. Combined with ADC, washout enhancement, arrival time (AT), peak enhancement intensity (PEI), K^trans , K_ep , V_e collectively were predictive of malignancy (P = 0.012). Combined washin, washout, time to peak (TTP), AT, and PEI values predicted malignancy (P = 0.043). There was good observer agreement for most noncontrast MRI biomarkers.

DATA CONCLUSION

MRI can contribute to pulmonary nodule analysis. Multiparametric MRI might be better than individual MRI biomarkers in pulmonary nodule risk stratification.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

Genomic alterations of ground-glass nodular lung adenocarcinoma

In-depth molecular pathogenesis of ground-glass nodular lung adenocarcinoma has not been well understood. The objectives of this study were to identify genomic alterations in ground-glass nodular lung adenocarcinomas and to investigate whether viral transcripts were detected in these tumors. Nine patients with pure (n = 4) and part-solid (n = 5) ground-glass nodular adenocarcinomas were included. Six were females with a median age of 58 years. We performed targeted exon sequencing and RNA sequencing. EGFR (n = 10), IDH2 (n = 2), TP53 (n = 1), PTEN (n = 1), EPHB4 (n = 1), and BRAF (n = 1) were identified as driver mutations by targeted exon sequencing. Vasculogenesis-associated genes including NOTCH4 and TGFBR3 expression were significantly downregulated in adenocarcinoma tissue versus normal tissue (adjusted P values < 0.001 for both NOTCH4 and TGFBR3). In addition, five novel fusion gene loci were identified in four lung adenocarcinomas. However, no significant virus-associated transcripts were detected in tumors. In conclusions, EGFR, IDH2, TP53, PTEN, EPHB4, and BRAF were identified as putative driver mutations of ground-glass nodular adenocarcinomas. Five novel fusion genes were also identified in four tumors. Viruses do not appear to be involved in the tumorigenesis of ground-glass nodular lung adenocarcinoma.

Aerogenous metastases: a potential game changer in the diagnosis and management of primary lung adenocarcinoma

OBJECTIVE

The purposes of this article are to summarize the relevant literature on aerogenous metastasis, explain the putative pathogenetic mechanism of aerogenous spread, present the characteristic imaging and pathologic features, and review the importance of aerogenous spread to staging and clinical management.

CONCLUSION

Cumulative evidence suggests that aerogenous spread may exist and is underrecognized. Imaging features are helpful in differentiating possible aerogenous spread of tumor from hematogenous and lymphatic metastases and from synchronous primary tumors. The putative occurrence of intrapulmonary aerogenous metastasis of lung cancer has staging, management, and prognostic implications.

Adenocarcinoma of the lung: current concepts in radiologic diagnosis and management

PURPOSE OF REVIEW

Since the introduction especially of multidetector computed tomography scanners, detection of peripheral pulmonary nodules as small as 2-3 mm is now a frequent event even in individuals without a significant smoking history. This preponderance of small indeterminate nodules has necessitated reconsideration of the natural history of malignant lung tumors, in particular peripheral adenocarcinomas, as well as current clinical and radiologic guidelines to aid in the management of these lesions.

RECENT FINDINGS

New information within the radiologic, pathologic and surgical literature is currently redefining nodule characterization. Most important has been the growing awareness of the prevalence of 'so-called' sub-solid pulmonary nodules, with important implications for revising our understanding of the natural history of these lesions as it impacts guidelines for nodule management.

SUMMARY

Reassessment of our approach to small pulmonary nodules, while controversial, is now requisite as newer insights into the computed tomography appearance and natural history of small adenocarcinomas of the lung become apparent. Recognition of suspicious morphology and accurate measurements of volume doubling time, in particular, should aid in the management of these lesions.

Focal area of ground-glass opacity and ground-glass opacity predominance on thin-section CT: Discrimination between neoplastic and non-neoplastic lesions

AIM

To reveal differences in thin-section computed tomography (CT) findings between lung neoplastic lesions and non-neoplastic lesions, which showed a focal area of ground-glass opacity or ground-glass opacity predominance.

MATERIALS AND METHODS

A total of 82 focal areas of ground-glass opacity and ground-glass opacity predominance, consisting of 38 neoplastic and 44 non-neoplastic lesions, were assessed retrospectively regarding their thin-section CT findings.

RESULTS

The frequency of wholly well-defined margin (p=0.001), spiculation (p=0.019), pleural indentation (p=0.016), air bronchograms (p=0.027), air-containing space (p=0.004) was significantly higher in neoplastic lesions than in non-neoplastic lesions. Thirty-four of 38 (89%) neoplastic lesions were well-defined in more than 50% of the circumference, of which nine had an air-containing space other than air bronchogram, whereas only one non-neoplastic lesion had these features.

CONCLUSION

A focal area of ground-glass opacity or ground-glass opacity predominance with a well-defined margin and air-containing space is more likely to be a neoplasm.

"Crazy-paving" pattern at thin-section CT of the lungs: radiologic-pathologic overview

The "crazy-paving" pattern is a common finding at thin-section computed tomography (CT) of the lungs. It consists of scattered or diffuse ground-glass attenuation with superimposed interlobular septal thickening and intralobular lines. This finding has a variety of causes, including infectious, neoplastic, idiopathic, inhalational, and sanguineous disorders. Specific disorders that can cause the crazy-paving pattern include Pneumocystis carinii pneumonia, mucinous bronchioloalveolar carcinoma, pulmonary alveolar proteinosis, sarcoidosis, nonspecific interstitial pneumonia, organizing pneumonia, exogenous lipoid pneumonia, adult respiratory distress syndrome, and pulmonary hemorrhage syndromes. Knowledge of the many causes of this pattern can be useful in preventing diagnostic errors. In addition, although the causes of this pattern are frequently indistinguishable at radiologic evaluation, differences in the location of the characteristic attenuation in the lungs, as well as the presence of additional radiologic findings, the patient's history, and the clinical presentation, can often be useful in suggesting the appropriate diagnosis.

Clinical characteristics of pneumonic-type adenocarcinoma of the lung

PURPOSE

To analyze diagnostic approaches, survival predictors, and treatment efficacy in pneumonic-type adenocarcinoma (P-ADC).

PATIENTS AND METHODS

Fifty-two patients with P-ADC diagnosed between January 1986 and December 2000 were studied. P-ADC was defined as histologically or cytologically proven pulmonary adenocarcinoma with a pneumonia-like consolidation, in a patient with no prior diagnosis of thoracic or extrathoracic adenocarcinoma.

RESULTS

Sixty percent of the patients were men (n = 31), and 65% (n = 34) were current or former smokers. Mean (+/- SD) age at diagnosis was 66 +/- 1.4 years. P-ADC was diagnosed by routine chest radiography in 17% of cases (n = 9). Bronchorrhea was present in 31% of cases (n = 16), and crepitant rales in 58% (n = 30). The primary tumor appeared as consolidations, which could not be assessed and were thus classified Tx, in 83% of the patients (n = 43). Ten percent of the patients (n = 5) had a satellite tumor within the lobe containing the primary tumor (T4), and 63% (n = 33) had a satellite tumor in another lobe (M1). Extrathoracic metastases were present in 5% of cases (n = 3). Bronchial biopsy, transbronchial biopsy, bronchial aspiration, and BAL were positive in 21%, 80%, 44%, and 66% of cases, respectively. The median survival time after diagnosis was 10.5 months (range, 1 to 150 months). The outcome of patients treated by lobectomy or bilobectomy was significantly better than that of patients treated with pneumonectomy, chemotherapy, or best supportive care (p < 0.01). Bronchorrhea and crepitant rales were independent predictors of shorter survival when the treatment modality (surgery vs no surgery) was not entered as a risk factor.

CONCLUSIONS

P-ADC is characterized by aerogenous propagation, as emphasized by the results of multivariate analysis showing that bronchorrhea and crepitant rales were the only two independent factors of shorter survival. Surgery remains the most effective treatment in P-ADC, especially when lobectomy is feasible. As CT is not sensitive enough to detect multifocal lesions, new tools are required to evaluate pulmonary involvement and thereby to refine the surgical strategy.

Lung nodule detection and characterization with multislice CT

The ability to identify and characterize pulmonary nodules has been dramatically increased by the introduction of multislice CT (MSCT) technology. Using high-resolution sections, MSCT allows considerable improvement in assessing nodule morphology, enhancement patterns, and growth. MSCT also has facilitated the development and potential of clinical application of computer-assisted diagnosis.

Localized pure ground-glass opacity on high-resolution CT: histologic characteristics

PURPOSE

The aim of this study is to assess the histologic characteristics in cases of localized pure ground-glass opacity (LPGGO) that do not exhibit consolidation on high-resolution CT (HRCT) images.

METHOD

Twenty surgically resected lesions from 20 consecutive cases were retrospectively investigated. Each of the 20 lesions had exhibited LPGGO on HRCT images. The HRCT images and histopathologic findings were examined for correlations.

RESULTS

The areas of LPGGO had a maximum diameter of 2.0-24 mm on the HRCT images. Histopathology of the LPGGO lesions resulted in diagnosis of fibrosis (n = 3; 15%), atypical adenomatous hyperplasia (n = 5; 25%), bronchioloalveolar carcinoma (n = 10; 50%), and adenocarcinoma with stromal invasion (n = 2; 10%). Nonaerogenous components corresponding to solid components without normal alveolar septal destruction were pathologically observed in 15 of the 20 lesions. The diameter of the nonaerogenous components varied between 0.2 and 2.0 mm.

CONCLUSION

Because 10% of LPGGO lesions include invasive disease, patients with LPGGO should undergo pathologic examination for confirmation.

Bronchioloalveolar carcinoma and adenocarcinoma with bronchioloalveolar features presenting as ground-glass opacities on CT

OBJECTIVE

As bronchioloalveolar carcinoma (BAC) is noninvasive but, in its later stages, has a worse prognosis than adenocarcinoma with bronchioloalveolar features (ACB), early identification and differentiation is important for therapeutic and prognostic purposes. We wanted to identify features of BAC, which differentiated it from ACB when both presented as ground-glass opacities (GGOs) on CT.

MATERIALS AND METHODS

We reviewed all pathologic specimens of patients who were diagnosed with BAC and ACB in the lung from 1991 to 1999 in our institution and whose malignancy presented as a GGO on CT. This yielded 29 patients, 15 with BAC and 14 with ACB with GGOs on CT. Both univariate frequency table and multivariate logistic regression approaches were used to analyze the CT characteristics of these GGOs (location, GGO pattern, size, shape, margin, presence and type of air bronchogram and pseudocavitation).

RESULTS

BAC most frequently had a "GGO halo" around a solid opacity, often was a GGO "mixed with consolidation" with the smallest BACs being "pure GGO." Air bronchograms were frequently present in the largest GGOs. Pseudocavitations were rare. ACB, on the other hand, most frequently presented as a GGO "mixed with consolidation," less frequently with a "GGO halo" and rarely with "superimposed lymphangitis." The air bronchograms, frequently present, were usually tortuous and ectatic. Pseudocavitation was present in about one-third of the cases. The most useful CT features of GGO in separating those due to BAC from those due to ACB were pure (uniform) ground-glass attenuation and absence of lymphangitis.

CONCLUSION

The CT features of BAC and ACB presenting as GGO reflect the histologic descriptions of these carcinomas.

MR white lung sign: incidence and significance in pulmonary consolidations

PURPOSE

The presence of a pulmonary consolidation with a signal intensity comparable with that of the static fluid on heavily T2-weighted MR images has been named the "MR white lung sign." This sign has been described in mucinous bronchioloalveolar carcinoma (BAC). Our purpose was to establish the frequency and significance of this sign in pulmonary consolidations of varied causes.

METHOD

In this prospective study, 83 patients with pulmonary consolidation underwent MR examination between January and December 1999. Segmental or lobar consolidations were due to pneumonia without central obstruction (n = 22), pneumonitis with central obstruction (n = 21), cicatricial atelectasis (n = 8), passive atelectasis (n = 10), radiation pneumonitis (n = 8), mucinous BAC (n = 5), infarction (n = 3), bronchiolitis obliterans organizing pneumonia (n = 3), nonmucinous BAC (n = 2), and lymphoma (n = 1). The MR white lung sign was considered present when the signal intensity of a pulmonary consolidation was comparable with that of the static fluid on heavily T2-weighted images obtained with MR hydrography sequences. Interobserver agreement, sensitivity, and specificity of the white lung sign in diagnosing mucinous BAC were calculated.

RESULTS

The MR white lung sign was present in 7 (8%) of 83 consolidations, including 5 (100%) of 5 cases of mucinous BAC and 2 (10%) of 21 cases of obstructive pneumonitis. The frequency of the white lung sign was 100% in mucinous BAC and 2.6% in consolidations due to other causes. The difference was statistically significant (p < 0.05).

CONCLUSION

The white lung sign is an uncommon finding in pulmonary consolidations evaluated with heavily T2-weighted sequences. However, the sign is characteristic of mucinous BAC and adds specificity to the radiologic diagnosis.

High-resolution CT analysis of small peripheral lung adenocarcinomas revealed on screening helical CT

OBJECTIVE

The purpose of this study was to determine the correlation between high-resolution CT morphologic features of small peripheral lung adenocarcinomas and tumor growth patterns.

MATERIALS AND METHODS

We examined high-resolution CT morphologic features of 59 small, surgically resected peripheral lung adenocarcinomas (diameter, 6-20 mm) that were detected on screening for lung cancer using low-dose helical CT. Among these adenocarcinomas, 14 (24%) were visible and 45 (76%) were invisible on conventional chest radiography. The correlation between high-resolution CT morphologic features and tumor growth patterns was analyzed.

RESULTS

Sixteen (94%) of 17 type A (Noguchi's classification) adenocarcinomas appeared as nodules of pure ground-glass attenuation (high-resolution CT type I). Ten (71%) of 14 type B tumors appeared as heterogeneous, low-attenuation nodules (type II). Seven (29%) of 24 type C tumors appeared as nodules with ground-glass attenuation in the periphery and a high-density central zone (type III), and 12 (50%) of 24 type C tumors appeared as homogeneous nodules with soft-tissue density (type IV). Among tumors with a replacement growth pattern, the size and CT values of type C tumors were larger than those of type A or type B tumors (p < 0.05), whereas the percentage of ground-glass attenuation and retained air space in type C tumors was smaller than those in type A or type B tumors (p < 0.01). All (100%) four type D tumors appeared to be homogeneous nodules with soft-tissue density (type IV).

CONCLUSION

Small peripheral lung adenocarcinomas shown on CT exhibit four high-resolution CT patterns that corresponded to the histopathologic findings of different tumor growth patterns.

Clinical pathway for impalpable or small lung lesions treated with coil marking and thoracoscopy

OBJECTIVES

Advances in computed tomography are detecting increasingly impalpable or small pulmonary lesions. We propose a clinical pathway for managing such lesions.

METHODS

We conducted a retrospective study in a community teaching hospital to describe the hospital schedules of 18 patients having 19 lesions 10 mm or less and ground glass attenuation. Under computed tomography, a coil (Complex Helical Fibered Platinum Coil-18) was placed at the proximal side of the lesion. Using thoracoscopy and radiographic fluorography, we conducted partial lung resection targeting the coil the next day, adding lobectomy, if required.

RESULTS

Final diagnosis included primary and metastatic lung cancer (n = 14), atypical adenomatous hyperplasia (n = 1), and benignancy (n = 4). Patients were admitted 2* days before surgery (*Numbers are medians). On postoperative day 3, chest tubes were removed. Epidural analgesia was continued for 5 days. On postoperative day 7, patients were discharged. Their admission charge was a total of yen 979,610.

CONCLUSIONS

The hospital course above may be applied to the clinical pathway for managing impalpable or small lung lesions.

Magnetic resonance imaging of bronchioloalveolar carcinoma

The purpose of this study is to describe the magnetic resonance (MR) features of bronchioloalveolar carcinoma. MR examinations of 18 patients with proven bronchioloalveolar carcinoma were reviewed. Detection at computed tomography (CT) and pathologic confirmation were the entry criteria. Nine patients had a solitary nodule, three patients a lobar consolidation, and six patients had diffuse disease. For each patient, both breath-hold T2-weighted fast spin-echo, and breath-hold T1-weighted gradient-echo images, before and after injection of gadolinium, were available. Nine patients with pulmonary consolidation or diffuse disease had also heavily T2-weighted MR imaging (Haste or TSE 240; Siemens, Erlangen, Germany). MR imaging showed pulmonary abnormalities in 17 of 18 patients. Unenhanced T1-weighted and T2-weighted images depicted tumor in 16 of 18 patients. Contrast-enhanced T1-weighted images showed tumor in 17 of 18 patients. In no case did MR imaging depict abnormalities corresponding to the ground-glass opacities seen on CT scans. In three patients with mucinous bronchioloalveolar carcinoma, heavily T2-weighted images showed lesions isointense with respect to static fluid of the human body. In conclusion, the ability of MR imaging in detecting small nodules and ground-glass opacities is limited. However, heavily T2-weighted sequences are able to show the presence of mucin. This is useful information because mucinous bronchioloalveolar carcinoma carries a poor prognosis.

Alternative imaging of the lung

This article illustrates the roles of ultrasonography, scintigraphy, and computed tomography (CT) as alternative techniques for pulmonary imaging in small animals. The advantages and limitations of each modality, normal anatomic features, and technical considerations will be discussed. Selected applications will be examined and include pulmonary consolidation, neoplasia and other masses, atelectasis, pneumothorax, dystrophic mineralization, diffuse infiltrative disease, and pulmonary embolism. The use of ultrasound and CT-guided interventional procedures will also be briefly discussed.