Evolution of peripheral lung adenocarcinomas: CT findings correlated with histology and tumor doubling time

Advances in oncologic imaging: update on 5 common cancers

Imaging has become a pivotal component throughout a patient's encounter with cancer, from initial disease detection and characterization through treatment response assessment and posttreatment follow-up. Recent progress in imaging technology has presented new opportunities for improving clinical care. This article provides updates on the latest approaches to imaging of 5 common cancers: breast, lung, prostate, and colorectal cancers, and lymphoma.

Screening for lung cancer

The National Lung Screening Study has demonstrated that screening with low-dose spiral computed tomography results in fewer deaths from lung cancer compared with screening with chest radiography (CXR). Previous trials of screening with CXR and sputum cytology failed to exhibit fewer deaths compared with no screening intervention. Early computed tomography (CT) studies showed promise for CT to be a more sensitive test, yet were unable to demonstrate sufficient evidence of efficacy. This review examines the problem of early lung cancer detection, the issues presented by screening, and results of past and recent studies of lung cancer screening.

One-dimensional mean computed tomography value evaluation of ground-glass opacity on high-resolution images

Objective

Differentiation of atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and invasive carcinoma on computed tomography (CT) is useful for determining “follow-up or resection” strategies for lesions displaying ground-glass opacity (GGO). The purpose of this study is to evaluate one-dimensional quantitative CT values of GGO on high-resolution CT (HRCT) images using computer-aided diagnosis.

Methods

Between April 2001 and March 2010, a total of 44 nodules in 42 patients with pure or mixed GGOs ≤2 cm were retrospectively evaluated. Maximum diameter and one-dimensional mean CT (m-CT) value of the diameter were measured using a computer graphics support system (HOPE/DrABLE-EX, Fujitsu, Tokyo, Japan) that displays a CT density profile across the tumor.

Results

m-CT values were −682 ± 64 HU (range) for AAH lesions, −544 ± 179 (range) for Type A lesions, −496 ± 147 (range) for Type B lesions, and −371 ± 142 (range) for invasive lesions. AAH lesions had a significantly lower m-CT value than Type B lesions. AAH, Type A, and Type B lesions had significantly lower m-CT values than invasive lesions (p < 0.05). All seven GGO lesions with a maximum diameter ≤1 cm and m-CT value ≤−600 HU were pre-invasive lesions, while 16 of 22 (73 %) cases with maximum diameter >1 cm and m-CT value >−600 HU were invasive lesions.

Conclusion

Observation may be indicated for GGO lesions with a maximum diameter ≤1 cm and m-CT value ≤−600 HU.

Serial 3-dimensional volumetric computed tomography evaluation of lung cancer growth rate in patients with chronic obstructive pulmonary disease findings

PURPOSE

The objectives of this study were to compare volume doubling time (VDT) of lung cancer with chronic obstructive pulmonary disease (COPD) findings with that without COPD findings using serial 3-dimensional (3D) volumetric computed tomography (CT) and to investigate the association between VDT and COPD findings.

METHODS

This study included 45 patients with surgically diagnosed non-small cell lung cancer with serial preoperative follow-up CT. Volume doubling time of the nodule was calculated by using 3D volumetric computer software.

RESULTS

Volume doubling time of lung cancer with COPD findings (n = 26) tended to be shorter than that without COPD findings (n = 19) (998 ± 2178 vs 2226 ± 6748 days; P = 0.066). Among COPD findings, severity and pattern of emphysema were significantly correlated with VDT (P < 0.001).

CONCLUSIONS

Volume doubling time of lung cancer with COPD findings on 3D volumetric CT tended to be shorter than that of lung cancer without COPD findings. Severe or paraseptal emphysema may be associated with short VDT of lung cancer with COPD findings.

Quantitative classification based on CT histogram analysis of non-small cell lung cancer: correlation with histopathological characteristics and recurrence-free survival

PURPOSE

Quantification of the CT appearance of non-small cell lung cancer (NSCLC) is of interest in a number of clinical and investigational applications. The purpose of this work is to present a quantitative five-category (α, β, γ, δ, and ɛ) classification method based on CT histogram analysis of NSCLC and to determine the prognostic value of this quantitative classification.

METHODS

Institutional review board approval and informed consent were obtained at the National Cancer Center Hospital. A total of 454 patients with NSCLC (maximum lesion size of 3 cm) were enrolled. Each lesion was measured using multidetector CT at the same tube voltage, reconstruction interval, beam collimation, and reconstructed slice thickness. Two observers segmented NSCLC nodules from the CT images by using a semi-automated three-dimensional technique. The two observers classified NSCLCs into one of five categories from the visual assessment of CT histograms obtained from each nodule segmentation result. Interobserver variability in the classification was computed with Cohen's κ statistic. Any disagreements were resolved by consensus between the two observers to define the gold standard of the classification. Using a classification and regression tree (CART), the authors obtained a decision tree for a quantitative five-category classification. To assess the impact of the nodule segmentation on the classification, the variability in classifications obtained by two decision trees for the nodule segmentation results was also calculated with the Cohen's κ statistic. The authors calculated the association of recurrence with prognostic factors including classification, sex, age, tumor diameter, smoking status, disease stage, histological type, lymphatic permeation, and vascular invasion using both univariate and multivariate Cox regression analyses.

RESULTS

The κ values for interobserver agreement of the classification using two nodule segmentation results were 0.921 (P < 0.001) and 0.903 (P < 0.001), respectively. The κ values for the variability in the classification task using two decision trees were 0.981 (P < 0.001) and 0.981 (P < 0.001), respectively. All the NSCLCs were classified into one of five categories (type α, n = 8; type β, n = 38; type γ, n = 103; type δ, n = 112; type ɛ, n = 193) by using a decision tree. Using a multivariate Cox regression analysis, the classification (hazard ratio 5.64; P = 0.008) and disease stage (hazard ratio 8.33; P < 0.001) were identified as being associated with an increased recurrence risk.

CONCLUSIONS

The quantitative five-category classifier presented here has the potential to provide an objective classification of NSCLC nodules that is strongly correlated with prognostic factors.

Evaluation of solitary pulmonary nodule detected during computed tomography examination

The solitary pulmonary nodule (SPN) has always been a diagnostic challenge for the radiologists. Currently, with increased utilization of computed tomography (CT) greater number of nodules is being discovered, with numerous indeterminate lesions, which frequently cannot be immediately classified into benign or malignant category.In this article we review the imaging features of benign and malignant round opacities; we demonstrate currently used standards and also more advanced techniques that are helpful in evaluating SPNs such as contrast-enhanced CT, PET/CT imaging and also pathologic sampling with biopsy or surgical resection.We also summarize the methods of evaluating and managing SPNs based on the latest guidelines from the Fleischner Society and American College of Chest Physicians.

Doubling times and CT screen–detected lung cancers in the Pittsburgh Lung Screening Study

RATIONALE

As computed tomography (CT) screening for lung cancer becomes more widespread, volumetric analyses, including doubling times, of CT-screen detected lung nodules and lung cancers may provide useful information in the follow-up and management of CT-detected lung nodules and cancers.

OBJECTIVES

To analyze doubling times in CT screen detected lung cancers and compare prevalent and nonprevalent cancers and different cell types on non small cell lung cancer.

METHODS

We performed volumetric and doubling time analysis on 63 non–small cell lung cancers detected as part of the Pittsburgh Lung Screening Study using a commercially available VITREA 2 workstation and VITREA VITAL nodule segmentation software.

MEASUREMENTS AND MAIN RESULTS

Doubling times (DT) were divided into three groups: rapid (DT<183 d), typical (DT 183–365 d), and slow (DT>365 d). Adenocarcinoma/bronchioloalveolar carcinoma comprised 86.7% of the slow DT group compared with 20% of the rapid DT group. Conversely, squamous cell cancer comprised 60% of the rapid DT group compared with 3.3% of the slow DT group. Twenty-eight of 42 (67%) prevalent and 2 of 21 (10%) nonprevalent cancers were in the slow DT group (P<0.0001; Fisher's exact test). Twenty-four of 32 (75%) prevalent and 1 of 11 (9%) nonprevalent adenocarcinomas were in the slow DT group (P<0.0002; Fisher's exact test).

CONCLUSIONS

Volumetric analysis of CT-detected lung cancers is particularly useful in AC/BAC. Prevalent cancers have a significantly slower DT than nonprevalent cancers and a higher percentage of adenocarcinoma/bronchioloalveolar carcinoma. These results should affect the management of indeterminant lung nodules detected on screening CT scans.

Accuracy and predictive features of FDG-PET/CT and CT for diagnosis of lymph node metastasis of T1 non-small-cell lung cancer manifesting as a subsolid nodule

OBJECTIVES

To retrospectively evaluate the diagnostic accuracy and predictive features of F-18 fluorodeoxyglucose positron emission tomography/ computed tomography (FDG-PET/CT) and CT in lymph node (LN) staging of T1 non-small-cell lung cancers (NSCLCs) manifesting as subsolid nodules.

METHODS

From January 2005 to May 2011, 160 patients with pathologically proven T1 subsolid NSCLCs with LN staging were included in this study. Diagnostic accuracies of FDG-PET/CT and CT for LN staging were evaluated. Maximum standardised uptake value (SUVmax) and CT features of primary tumours were evaluated to investigate predictive factors for LN metastasis.

RESULTS

LN metastases were found in nine of the 160 patients (5.6%). No LN metastasis was present in patients with a solid proportion ≤50%. Sensitivity, specificity and accuracy of FDG-PET/CT for LN staging on a per-patient basis were 11.1%, 86.1% and 81.9%; those of CT were 11.1%, 96.7% and 91.9%. Among patients with a solid proportion >50%, there were significant differences in SUVmax, solid portion size, solid proportion and lesion location between patients with and without LN metastasis. Multivariate analysis revealed that higher SUVmax, a larger solid proportion and central location were independent predictors of LN metastasis.

CONCLUSIONS

FDG-PET/CT adds little value to CT in the lymph node staging of T1 subsolid NSCLCs.

KEY POINTS

Lymph node (LN) metastases are important in non-small-cell lung cancer (NSCLC). • Positron emission tomography (PET) helps to stage solid NSCLCs. • FDG-PET/CT adds little to the LN staging of T1 subsolid NSCLCs. • No LN metastasis in patients with a solid proportion ≤50%. • LN metastasis is more common in solid and/or centrally sited tumours.

Small peripheral lung adenocarcinoma: CT and histopathologic characteristics and prognostic implications

Since the introduction of computed tomography (CT), detection of small lung cancer, especially small peripheral adenocarcinoma, is common. Recently, the morphological characteristics, including thin-section CT and pathologic findings, and prognosis of small peripheral lung adenocarcinomas have been studied extensively. The radiologic and microscopic findings correlate well with each other and are closely associated with tumour prognosis. Most importantly, some subtypes of small lung adenocarcinomas with specific CT or pathologic features are curable. Therefore, all defining characteristics (CT, pathologic and prognostic) of this kind of tumour should be integrated to improve our understanding, provide guidelines for management and accurately assess its prognosis.

Long term follow-up for small pure ground-glass nodules: implications of determining an optimum follow-up period and high-resolution CT findings to predict the growth of nodules

PURPOSE

To identify the optimum follow-up period for pure ground-glass nodules (GGN) measuring less than 15 mm in diameter, and to evaluate whether the initial HRCT findings can be used as predictors for the progression of pure GGN.

MATERIALS AND METHODS

A total of 150 pure GGNs present in 111 patients were evaluated. The series of HRCT images for each GGN at the time of the initial detection, 2 years after detection, and at the final follow-up were evaluated. The HRCT findings of GGN were compared between the "increasing nodule" and "non-increasing nodule" groups.

RESULTS

Most (87.3%) pure GGN did not increase whereas some nodules (12.7%) eventually increased after long-term follow-up (mean 66.0 ± 25.0 months). Six (31.6%) out of the 19 increasing nodules were regarded as stable at the 2 year follow-up examination. Some morphological findings on initial HRCT, including a size greater than 10 mm (p = 0.001), lobulated margins (p = 0.015), and a bubble-like appearance (p = 0.002), were significantly associated with the growth of pure GGNs.

CONCLUSION

More than 2 years of follow-up are necessary to detect the growth of pure GGNs. Some characteristic findings indicated a high likelihood of future growth of the GGN.

Multidetector CT features of pulmonary focal ground-glass opacity: differences between benign and malignant

OBJECTIVE

To evaluate different features between benign and malignant pulmonary focal ground-glass opacity (fGGO) on multidetector CT (MDCT).

METHODS

82 pathologically or clinically confirmed fGGOs were retrospectively analysed with regard to demographic data, lesion size and location, attenuation value and MDCT features including shape, margin, interface, internal characteristics and adjacent structure. Differences between benign and malignant fGGOs were analysed using a χ(2) test, Fisher's exact test or Mann-Whitney U-test. Morphological characteristics were analysed by binary logistic regression analysis to estimate the likelihood of malignancy.

RESULTS

There were 21 benign and 61 malignant lesions. No statistical differences were found between benign and malignant fGGOs in terms of demographic data, size, location and attenuation value. The frequency of lobulation (p=0.000), spiculation (p=0.008), spine-like process (p=0.004), well-defined but coarse interface (p=0.000), bronchus cut-off (p=0.003), other air-containing space (p=0.000), pleural indentation (p=0.000) and vascular convergence (p=0.006) was significantly higher in malignant fGGOs than that in benign fGGOs. Binary logistic regression analysis showed that lobulation, interface and pleural indentation were important indicators for malignant diagnosis of fGGO, with the corresponding odds ratios of 8.122, 3.139 and 9.076, respectively. In addition, a well-defined but coarse interface was the most important indicator of malignancy among all interface types. With all three important indicators considered, the diagnostic sensitivity, specificity and accuracy were 93.4%, 66.7% and 86.6%, respectively.

CONCLUSION

An fGGO with lobulation, a well-defined but coarse interface and pleural indentation gives a greater than average likelihood of being malignant.

Decision making in patients with pulmonary nodules

Integrating current evidence with fundamental concepts from decision analysis suggests that management of patients with pulmonary nodules should begin with estimating the pretest probability of cancer from the patient's clinical risk factors and computed tomography characteristics. Then, the consequences of treatment should be considered, by comparing the benefits of surgery if the patient has lung cancer with the potential harm if the patient does not have cancer. This analysis determines the "treatment threshold," which is the point around which the decision centers. This varies widely among patients depending on their cardiopulmonary reserve, comorbidities, and individual preferences. For patients with a very low probability of cancer, careful observation with serial computed tomography is warranted. For those with a high probability of cancer, surgical diagnosis is warranted. For patients in the intermediate range of probabilities, either computed tomography-guided fine-needle aspiration biopsy or positron emission tomography, possibly followed by computed tomography-guided fine-needle aspiration biopsy, is best. Patient preferences should be considered because the absolute difference in outcome between strategies may be small. The optimal approach to the management of patients with pulmonary nodules is evolving as technologies develop. Areas of uncertainty include quantifying the hazard of delayed diagnosis; determining the optimal duration of follow-up for ground-glass and semisolid opacities; establishing the roles of volumetric imaging, advanced bronchoscopic technologies, and limited surgical resections; and calculating the cost-effectiveness of different strategies.

Screen-detected lung cancer: a retrospective analysis of CT appearance

RATIONALE AND OBJECTIVES

The aim of this study was to retrospectively evaluate characteristics of lung cancers diagnosed in a low-dose computed tomographic lung cancer screening study.

MATERIALS AND METHODS

As part of the International Early Lung Cancer Action Program, a cohort of 4782 at-risk participants were screened. A total of 86 cancers in 84 individuals were detected and evaluated for location, morphology (density, border), size, histology, stage at diagnosis, treatment, and survival. Follow-up imaging for computation of growth rates was available in 41 cases.

RESULTS

Eighty-six cancers were detected in 84 individuals (60 women, 24 men). Of these, seven (8%) were incidence cancers. Most cancers were radiologically described as solid (n = 52 [61%]). The median tumor size was 18 × 13 mm (range, 6-56 mm). Histopathologic diagnoses revealed 10 (11.6%) bronchoalveolar carcinomas, 55 (64%) adenocarcinomas, 11 (12.8%) squamous-cell carcinomas, two (2.3%) large-cell carcinomas, three (3.5%) carcinoids, and five (5.8%) small-cell lung cancers. Of the 41 cases with follow-up computed tomographic scans, 36 nodules had increased in size. The mean doubling time for all cancers was 259 days (median, 154 days). In women (n = 25), the mean doubling time was 313 days (median, 156 days), while in men (n = 11), the mean doubling time was 137 days (median, 92 days). Overall, 55 lung cancers (68%) were stage I. Most cancers (n = 62 [73%]) were surgically resected.

CONCLUSIONS

In this cohort, screening detected lung cancer in early treatable stages, and women had more slow-growing adenocarcinomas than men. Most screen-detected lung cancers were surgically resectable.

Ground-glass opacity lesions on computed tomography during postoperative surveillance for primary non-small cell lung cancer

Improvement in chest high-resolution computed tomography (CT) has increased the detection of ground-glass opacity (GGO) lesions. However, there is no clear therapeutic consensus about concurrent GGO lesions detected during postoperative follow-up chest CT after treatment for primary lung cancer. This study retrospectively and prospectively investigated 21 patients in whom 53 GGO lesions were detected during postoperative follow-up CT of non-small cell lung cancer at Kyushu University Hospital from April 2009 to February 2010. We investigated clinicopathological factors, such as age, gender, lesion number, size, laterality, time of identification, and enlargement or emergence of the inner solid component. The malignancy rate of the concurrent GGO lesions was assessed by log-rank test in the Kaplan-Meier curves. Twenty percent of the 53 GGO lesions had malignant radiological findings during the 5-year follow-up after they were first identified by CT. The newly emerging GGO lesions at postoperative CT had significantly more malignant radiological findings (39.5%) than other GGO lesions (9.5%). Three potentially malignant GGO lesions were treated by surgical resection and three were treated by stereotactic radiotherapy. These six treated GGO lesions showed a good clinical course without recurrence after treatment. Special attention should be paid to newly emerging GGO lesions after resection of primary non-small cell lung cancer. It is necessary to select an appropriate treatment, taking account of various factors such as the laterality and number of GGO lesions or the pathological stage of the postoperative lung cancer.

Small peripheral lung carcinomas with five-year post-surgical follow-up: assessment by semi-automated volumetric measurement of tumour size, CT value and growth rate on TSCT

OBJECTIVES

To retrospectively assess the utility of semi-automated measurements by stratification of CT values of tumour size, CT value and doubling time (DT) using thin-section computed tomography (CT) images. The post-surgical outcomes of favourable and problematic tumours (more advanced p stage than IA, post-surgical recurrence or mortality from lung cancer) were compared using the measured values. The computed DTs were compared with manually measured values.

METHODS

The study subjects comprised 85 patients (aged 33-80 years, 48 women, 37 men), followed-up for more than 5 years postoperatively, with 89 lung lesions, including 17 atypical adenomatous hyperplasias and 72 lung cancers. DTs were determined in 45 lesions.

RESULTS

For problematic lesions, whole tumour diameter and density were >18 mm and >-400 HU, respectively. The respective values for the tumour core (with CT values of -350 to 150 HU) were >15 mm and >-70 HU. Analysis of tumour core DTs showed interval tumour progression even if little progress was seen by standard tumour volume DT (TVDT).

CONCLUSION

Software-based volumetric measurements by stratification of CT values provide valuable information on tumour core and help estimate tumour aggressiveness and interval tumour progression better than standard manually measured 2D-VDTs.

Inappropriate application of nodule management guidelines in radiologist reports before and after revision of exclusion criteria

OBJECTIVE

The purpose of this study was to retrospectively evaluate appropriate and inappropriate application of nodule management guidelines in radiology reports of pulmonary nodules seen at CT.

MATERIALS AND METHODS

The CT reports of 181 patients examined in July and August 2007 (94 males, 87 females; age range, 2-88 years; mean, 60.3 ± 13.0 years) and 177 patients examined in March 2009 (106 men, 71 women; age range, 24-91 years; mean, 60.7 ± 14.0 years) were retrospectively reviewed to assess whether nodule management guidelines were inappropriately applied. The exclusion criteria for the 2007 cases included multiple nodules, stable nodules, potential metastatic disease, probable infectious or inflammatory cause, and age younger than 35 years. The exclusion criteria for the 2009 cases were all of the 2007 criteria except multiple nodules.

RESULTS

Guidelines were inappropriately applied 105 times in 2007 and 25 times in 2009. Reasons for inappropriate use in 2007 were multiple nodules in 70 of the 105 cases (67%), potential metastatic disease in 25 cases (24%), age younger than 35 years in four cases (4%), stable nodules in two cases (2%), probable infectious or inflammatory cause in two cases (2%), and protocol not included despite absence of exclusion criteria in two cases (2%). The reasons in 2009 were potential metastatic disease in 15 of the 25 cases (60%), age younger than 35 years in four cases (16%), stable nodules in three cases (12%), probable infectious or inflammatory cause in one case (4%), and protocol not included despite absence of exclusion criteria in two cases (8%). The percentage of cases with at least one error was 48.1% in 2007, significantly higher than the 13.6% in 2009 (p < 0.001).

CONCLUSION

Inappropriate application of guidelines for management of pulmonary nodules seen at CT was significantly reduced by removing multiple nodules from the exclusion criteria. Otherwise, causes for inappropriate application remained stable.

Volume-doubling time of pulmonary nodules with ground glass opacity at multidetector CT: Assessment with computer-aided three-dimensional volumetry

RATIONALE AND OBJECTIVES

To investigate the volume-doubling time (VDT) of histologically proved pulmonary nodules showing ground glass opacity (GGO) at multidetector CT (MDCT) using computer-aided three-dimensional volumetry.

MATERIALS AND METHODS

We retrospectively evaluated 47 GGO nodules (mixed n = 28, pure n = 19) that had been examined by thin-section helical CT more than once. They were histologically confirmed as atypical adenomatous hyperplasia (AAH, n = 13), bronchioloalveolar carcinoma (BAC, n = 22), and adenocarcinoma (AC, n = 12). Using computer-aided three-dimensional volumetry software, two radiologists independently performed volumetry of GGO nodules and calculated the VDT using data acquired from the initial and final CT study. We compared VDT among the three pathologies and also compared the VDT of mixed and pure GGO nodules.

RESULTS

The mean VDT of all GGO nodules was 486.4 ± 368.6 days (range 89.0-1583.0 days). The mean VDT for AAH, BAC, and AC was 859.2 ± 428.9, 421.2 ± 228.4, and 202.1 ± 84.3 days, respectively; there were statistically significant differences for all comparative combinations of AAH, BAC, and AC (Steel-Dwass test, P < .01). The mean VDT for pure and mixed GGO nodules was 628.5 ± 404.2 and 276.9 ± 155.9 days, respectively; it was significantly shorter for mixed than pure GGO nodules (Mann-Whitney U-test, P < .01).

CONCLUSION

The evaluation of VDT using computer-aided volumetry may be helpful in assessing the histological entities of GGO nodules.

CT fluoroscopy-guided cutting needle biopsy of focal pure ground-glass opacity lung lesions: diagnostic yield in 83 lesions

OBJECTIVE

The objective of our study was to retrospectively determine the diagnostic yield of CT fluoroscopy-guided cutting needle biopsy of focal pure ground-glass opacity lung lesions.

MATERIALS AND METHODS

Biopsies were performed using 20-G coaxial cutting needles for 83 focal pure ground-glass opacity lung lesions (mean lesion size, 12.1mm). After excluding the lesions for which biopsy specimens were unobtainable and final diagnoses were undetermined, the diagnostic yield, including sensitivity and specificity for a diagnosis of malignancy and accuracy, was calculated. The lesions were then divided into 2 groups: the diagnostic failure group, comprising lesions with false-negative results and for which a biopsy specimen was unobtainable; and the diagnostic success group, comprising lesions with true-negative results and true-positive results. Various variables were compared between the 2 groups by univariate analysis.

RESULTS

Biopsy specimens were obtained from 82 lesions, while specimens could not be obtained from 1 lesion. Final diagnosis was undetermined in 16 lesions. The sensitivity and specificity for a diagnosis of malignancy were 95% (58/61) and 100% (5/5), respectively. Diagnostic accuracy was 95% (63/66). The 4 lesions in diagnostic failure group were smaller, deeper, and more likely to be located in the lower lobe and further, for those lesions, number of specimens obtained was smaller, compared with 63 lesions in diagnostic success group. However, none of the differences were statistically significant.

CONCLUSION

CT fluoroscopy-guided cutting needle biopsy provided high diagnostic yield for focal pure ground-glass opacity lung lesions.

Progression of non-small-cell lung cancer during the interval before stereotactic body radiotherapy

PURPOSE

To investigate the relationship between waiting time (WT) and disease progression in patients undergoing stereotactic body radiotherapy (SBRT) for lung adenocarcinoma (AD) or squamous cell carcinoma (SQ).

METHODS AND MATERIALS

201 patients with Stage I AD or SQ undergoing SBRT between January 2004 and June 2010 were analyzed. The WT was defined as the interval between diagnostic computed tomography before referral and computed tomography for treatment planning or positioning before SBRT. Tumor size was measured on the slice of the longest tumor diameter, and tumor volume was calculated from the longest diameter and the diameter perpendicular to it. Changes in tumor volume and TNM stage progression were evaluated, and volume doubling time (VDT) was estimated.

RESULTS

The median WT was 42 days (range, 5-323 days). There was a correlation between WT and rate of increase in volume in both AD and SQ. The median VDTs of AD and SQ were 170 and 93 days, respectively. Thirty-six tumors (23%) did not show volume increase during WTs >25 days. In 41 patients waiting for ≤4 weeks, no patient showed T stage progression, whereas in 25 of 120 (21%) patients waiting for >4 weeks, T stage progressed from T1 to T2 (p = 0.001). In 10 of 110 (9.1%) T1 ADs and 15 of 51 (29%) T1 SQs, T stage progressed (p = 0.002). N stage and M stage progressions were not observed.

CONCLUSION

Generally, a WT of ≤4 weeks seems to be acceptable. The WT seems to be more important in SQ than in AD.

[Study on solitary pulmonary nodules: correlation between diameter and clinical manifestation and pathological features]

背景与目的

孤立性肺结节（solitary pulmonary nodules, SPN）是临床诊治的难题之一，不同直径大小SPN的临床及病例特点可能各不相同。本研究旨在探讨SPN直径大小与临床及病理之间的关系。

方法

收集2000年1月-2009年7月在北京大学人民医院胸外科经手术切除明确病理诊断的SPN患者共390例。其中男性212例，女性178例。平均年龄57.1岁；结节最大径平均2.02 cm。按SPN最大径进行分组，其中最大径≤0.5 cm 16例（A组），0.5 cm-1 cm 58例（B组），1 cm-2 cm 163例（C组），2 cm-3 cm 153例（D组），比较各组的临床表现及病理特点。

结果

肿瘤剜除术20例，楔形切除153例，肺叶切除217例。术后病理：良性病变130例（33.3%），恶性病变260例（66.7%）。58.5%的SPN不伴有临床症状，随着结节直径增大，出现临床症状的比率有逐渐增高趋势。A、B、C、D四组的恶性比率分别为43.7%、50.0%、63.2%、79.1%，随着结节直径增大，恶性肿瘤机率显著增加，差异有统计学意义（χ²=22.535, P < 0.001）。单因素及多因素Logistic回归分析结果显示，SPN直径大小是良恶性判断的独立危险因素（OR=1.922, P < 0.001）。本组14例患者术前观察时间达到或超过2年，其中10例术后为恶性，观察期间无增大者7例，3例证实为恶性（42.9%）。

结论

SPN直径大小与患者是否伴有临床症状相关，是病理性质判断的重要危险因素。临床发现的SPN应早期诊断，及时治疗。

A clinicopathological study of resected non-small cell lung cancers 2 cm or less in diameter: a prognostic assessment

The detection and diagnosis of small-sized (2 cm or less) non-small cell lung cancer (NSCLC) has increased with the development of computed tomography (CT). Over 80% of 5-year survival rate has been reported in surgically treated peripheral lung cancer. There are systematic mediastinal and hilar lymph node involvement pleural invasion and intrapulmonary metastasis even with tumor diameter less than 2 cm. The appropriate surgical procedure for such kinds of lung cancer is lobectomy with mediastinal lymph node dissection. To evaluate the prognostic factors and establish the optimal surgical strategy, we analyzed the clinicopathologic features and survival benefit in different tumor size of peripheral small-sized NSCLC. Among the resected lung cancer cases between January 1999 and July 2001, 185 patients were retrospectively analyzed in surgical methods, lymph node involvement, CT scan findings and survival rates. Survival was analyzed by Kaplan-Meier method and log-rank test. Lymph node involvement was recognized in 26(14.05%) patients. There was no statistically significant difference in the incidence of lymph node involvement between tumors 1.6-2.0 cm (17.82%) in diameter than in those 1.0-1.5 cm (11.94%). There was no lymph node metastasis in tumors less than 1.0 cm in diameter. The 5-year survival rates with or without lymph node involvement were 89.98 and 46.15%, respectively, showing significant difference (P=0.000). The overall 5-year survival rate was 83.78%. The 5-year survival rate in tumors 1.6-2.0 cm, 1.0-1.5 cm and less than 1.0 cm in diameter was 80.20, 85.07 and 100%, respectively, and showing significant difference (P=0.035). The 5-year survival rate of 19 patients showing ground-glass opacity (GGO) on CT scan was 94.74% without any metastasis and recurrence after operation. There are systematic mediastinal and hilar lymph node involvement even with tumor diameter less than 2 cm. The results of the present study suggested that systematic lymph node dissection is necessary even for cases with tumor diameter less than 2 cm. However, if the tumor is within 1.0 cm in diameter with obvious GGO showing on chest CT scan, these are good candidates for partial resection without mediastinal lymph node dissection.

Growth rate of newly developed metastatic brain tumors after thoracotomy in patients with non-small cell lung cancer

Among 1372 lung cancer patients without brain metastasis that underwent resection of lung cancer at our center from 2001 to 2007, brain metastases developed in 72 patients (5.2%) during their hospital course. We hypothesized that there were micro-metastases in the brain at the time of lung surgery in these patients, even though there were no detectable brain metastases on the MRI. The purpose of this study was to evaluate the growth rates of metastatic brain tumors in this unique subset of patients, and to compare the findings with our previous study that calculated the growth rate of brain metastases during chemotherapy. Among 72 patients, 23 with cystic or hemorrhagic metastases were excluded. Seventy-six metastatic brain tumors in 49 patients were reviewed. Twenty-five patients underwent adjuvant or neoadjuvant chemotherapy; however, for the rest of the patients, chemotherapy was not added after lung cancer surgery. The tumor volume was determined using V-works software (v. 4.0) (Cybermed, Seoul, Korea) and T1 gadolinium enhanced MR images. The overall median tumor growth rate was 11.7 mm³/day (interquartile range, 4.9-26.8). There were no statistically significant differences in the tumor growth among the lung cancer stages and the growth rate was similar regardless of the use of chemotherapy. The growth rate reported in this study shows consistency with that of our previous report (12.1 mm³/day). These findings may help optimize patient management during follow up.

Correlations of thin-section computed tomographic, histopathological, and clinical findings of adenocarcinoma with a bubblelike appearance

OBJECTIVE

We reported that adenocarcinomas with a bubblelike appearance (BLA) appear similar to old inflammation (J Comput Assist Tomogr 2009;33:42-48). The histopathological, clinical, and biological characteristics of adenocarcinomas with BLA need more investigation.

METHODS

We retrospectively reviewed the records of 26 patients who had undergone surgical resection between 1993 and 2008. We analyzed correlations between thin-section computed tomographic (TS-CT), histopathological, and clinical findings. We analyzed epidermal growth factor receptor and K-ras gene mutations.

RESULTS

The TS-CT findings are unique with one pattern that was the same in all the 26 cases: (1) polygonal with straight and concave margins, (2) slight peripheral ground-glass opacity areas, (3) 3 or more dilated air bronchograms, and (4) clear pleural indentations. The histopathological findings were identical with our TS-CT findings. The mean tumor doubling time was 1165 days. Epidermal growth factor receptor mutations were observed in 17 cases. There were no K-ras mutations. After resection, the 5-year survival rate is 100%.

CONCLUSION

The adenocarcinomas with BLA have unique TS-CT, histopathological, and clinical findings.

Stepwise evolution from a focal pure pulmonary ground-glass opacity nodule into an invasive lung adenocarcinoma: an observation for more than 10 years

The natural chronologic evolution of a lung cancer manifesting as a pure ground-glass opacity (GGO) nodule on CT scans still remains to be elucidated. Therefore, it is sometimes difficult to determine proper follow-up examinations, particularly in case of GGO nodule growing slowly on serial CT scans. In the current case, we demonstrate serial morphologic (CT) and metabolic ((18)F-FDG PET) imaging findings in a case of adenocarcinoma, where stepwise progression from a focal pure GGO nodule (presumed atypical adenomatous hyperplasia [AAH] or bronchioloalveolar carcinoma [BAC]) eventually to an invasive adenocarcinoma was clearly depicted for more than 10-year follow-up period. This case seems to be useful for the prediction of tumor growth pattern and aggressiveness of malignant pure GGO nodules. In addition, the evolving process of this case may suggest a guideline for planning an appropriate follow-up examination and management in such cases.

Computer-aided volumetry of pulmonary nodules exhibiting ground-glass opacity at MDCT

OBJECTIVE

The purpose of this study was to investigate the accuracy and reproducibility of results acquired with computer-aided volumetry software during MDCT of pulmonary nodules exhibiting ground-glass opacity.

MATERIALS AND METHODS

To evaluate the accuracy of computer-aided volumetry software, we performed thin-section helical CT of a chest phantom that included simulated 3-, 5-, 8-, 10-, and 12-mm-diameter ground-glass opacity nodules with attenuation of -800, -630, and -450 HU. Three radiologists measured the volume of the nodules and calculated the relative volume measurement error, which was defined as follows: (measured nodule volume minus assumed nodule volume / assumed nodule volume) x 100. Two radiologists performed two independent measurements of 59 nodules in humans. Intraobserver and interobserver agreement was evaluated with Bland-Altman methods.

RESULTS

The relative volume measurement error for simulated ground-glass opacity nodules measuring 3 mm ranged from 51.1% to 85.2% and for nodules measuring 5 mm or more in diameter ranged from -4.1% to 7.1%. In the clinical study, for intraobserver agreement, the 95% limits of agreement were -14.9% and -13.7% and -16.6% to 15.7% for observers A and B. For interobserver agreement, these values were -16.3% to 23.7% for nodules 8 mm in diameter or larger.

CONCLUSION

With computer-aided volumetry of ground-glass opacity nodules, the relative volume measurement error was small for nodules 5 mm in diameter or larger. Intraobserver and interobserver agreement was relatively high for nodules 8 mm in diameter or larger.

High-resolution computed tomography screening for lung cancer: unexpected findings and new controversies regarding adenocarcinogenesis

CONTEXT

Recent advances in human imaging technologies reawakened interest in lung cancer screening. Although historic and current preliminary and noncontrolled studies have not shown a decrease in lung cancer mortality in screened populations, many explanations have been proffered while the lung cancer community awaits the results of several large controlled population studies.

OBJECTIVE

To critically review the current model of adenocarcinoma development against the background of lung cancer screening results combined with observational pathologic and radiographic studies.

DATA SOURCES

Published articles pertaining to lung cancer screening, lung adenocarcinoma pathology, and radiology accessible through PubMed form the basis for this review.

CONCLUSIONS

The current adenocarcinogenesis model is probably valid for many but not all lung adenocarcinomas. Screening data combined with radiographic and pathologic studies suggest that not all lung adenocarcinomas are clinically aggressive, and it is uncertain whether all aggressive adenocarcinomas arise from identified precursors.

[Localized pure or mixed ground-glass lung opacities]

Localized ground-glass opacities (GGOs) have been recently individualized and account for between 2.9% and 19% of all pulmonary nodules detected in high-risk patients included in CT screening series for lung cancer. These opacities, nodular, lobular or flat, correspond to benign lesions (localised infectious and inflammatory diseases, focal interstitial fibrosis, and atypical alveolar hyperplasia) or malignant lesions (bronchioloalveolar carcinoma, early-stage adenocarcinoma and sometimes metastases). Localized GGOs are more likely to be malignant than solid nodules and prognosis is related to the percentage of the ground-glass component. However, doubling time of pure localized malignant GGOs is longer than mixed localized malignant GGOs and even longer than the doubling time of solid malignant nodules. Therefore, localized GGOs warrant a dedicated diagnostic workup.

HRCT features of small peripheral lung carcinomas detected in a low-dose CT screening program

RATIONALE AND OBJECTIVES

To define high-resolution computed tomography (HRCT) features of lung cancers detected by computed tomography (CT) screening according to histopathology and prognosis.

METHODS AND MATERIALS

Tumor size, CT value, morphology, and tumor volume doubling time (TVDT) were determined for 10 atypical adenomatous hyperplasias (AAH) and 50 lung cancers followed between 1996 and 1998 to 2007.

RESULTS

For the 10 AAHs, the density less than -500 HU in all lesions (mean, -654 HU) and the size was up to 14 mm (mean, 9 mm); all patients remain alive. Focal bronchioloalveolar cell carcinomas (BAC) were denser (mean, -537 HU) than AAH and mostly less dense than -350 HU; all patients remain alive. All 22 adenocarcinomas (ADC) were denser than -450 HU (mean, -186 HU); 6 were problematic and measured >-150HU and >10 mm or had >10 mm of central denser zone (CDZ) (partly solid tumors) or tumor size (solid tumor). Two of four squamous cell carcinomas (SCC) measuring 15 and 10 mm, respectively, were problematic. Two patients with small-cell lung carcinomas (SCLC) measuring 15 and 23 mm, respectively, remain alive. AAH, BAC, ADC, and SCC lesions were in general polygonal in shape. SCLC lesions appeared as round nodules with excrescence. The mean TVDT for AAH, BAC, ADC, SCC, and SCLC was 1278, 557, 466, 212, and 103 days, respectively.

CONCLUSION

The CT features reflected tumor aggressiveness. Non-SCLC lesions of >-150HU and >10 mm (or >-100HU and >10 mm for the solid portion of the tumor) are associated with unfavorable prognosis. Timely interventions should be undertaken before problematic increase in number of cases.