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

Volumetric measurement of pulmonary nodules at low-dose chest CT: effect of reconstruction setting on measurement variability

OBJECTIVE

To assess volumetric measurement variability in pulmonary nodules detected at low-dose chest CT with three reconstruction settings.

METHODS

The volume of 200 solid pulmonary nodules was measured three times using commercially available semi-automated software of low-dose chest CT data-sets reconstructed with 1 mm section thickness and a soft kernel (A), 2 mm and a soft kernel (B), and 2 mm and a sharp kernel (C), respectively. Repeatability coefficients of the three measurements within each setting were calculated by the Bland and Altman method. A three-level model was applied to test the impact of reconstruction setting on the measured volume.

RESULTS

The repeatability coefficients were 8.9, 22.5 and 37.5% for settings A, B and C. Three-level analysis showed that settings A and C yielded a 1.29 times higher estimate of nodule volume compared with setting B (P = 0.03). The significant interaction among setting, nodule location and morphology demonstrated that the effect of the reconstruction setting was different for different types of nodules. Low-dose CT reconstructed with 1 mm section thickness and a soft kernel provided the most repeatable volume measurement.

CONCLUSION

A wide, nodule-type-dependent range of agreement between volume measurements with different reconstruction settings suggests strict consistency is required for serial CT studies.

Stochastic population dynamic effects for lung cancer progression

The multistage paradigm is widely used in quantitative analyses of radiation-influenced carcinogenesis. Steps such as initiation, promotion and transformation have been investigated in detail. However, progression, a later step during which malignant cells produced in the earlier steps can develop into clinical cancer, has received less attention in computational radiobiology; it has often been approximated deterministically as a fixed, comparatively short, lag time. This approach overlooks important mechanisms in progression, including stochastic extinction, possible radiation effects on tumor growth, immune suppression and angiogenic bottlenecks. Here we analyze tumor progression in background and in radiation-induced lung cancers, emphasizing tumor latent times and the stochastic extinction of malignant lesions. A Monte Carlo cell population dynamics formalism is developed by supplementing the standard two-stage clonal expansion (TSCE) model with a stochastic birth-death model for proliferation of malignant cells. Simulation results for small cell lung cancers and lung adenocarcinomas show that the effects of stochastic malignant cell extinction broaden progression time distributions drastically. We suggest that fully stochastic cancer progression models incorporating malignant cell kinetics, dormancy (a phase in which tumors remain asymptomatic), escape from dormancy, and invasiveness, with radiation able to act directly on each phase, need to be considered for a better assessment of radiation-induced lung cancer risks.

Limited resection for noninvasive bronchioloalveolar carcinoma diagnosed by intraoperative pathologic examination

BACKGROUND

The establishment of limited resection procedures for non-small cell lung cancer is expected. Many groups have suggested noninvasive bronchioloalveolar carcinoma (BAC) to be a potential indication for limited resection.

METHODS

We designed a prospective phase II study evaluating limited resection for noninvasive BAC diagnosed by intraoperative pathologic examination. From 1999 to 2007, limited resection was the procedure in 46 patients (16 men and 30 women; median age, 69 years; range, 49 to 83) who were diagnosed intraoperatively as having noninvasive BAC. The first end point was the predictive value of the intraoperative pathologic examination for noninvasive BAC diagnosis. The second end point was overall survival, disease-free survival, and cancer-specific survival, calculated using the Kaplan-Meier method.

RESULTS

We performed wedge resections for 44 patients and segmentectomy for 2 patients. Permanent pathologic examination revealed 3 patients had primary lung adenocarcinomas other than noninvasive BAC. The predictive value of intraoperative pathologic examination for noninvasive BAC diagnosis was 94%. During a median 51-month follow-up, there were only 2 cancer unrelated deaths. The 5-year overall survival rate and the disease-free survival rate were 93%, and the 5-year cancer-specific survival rate was 100%.

CONCLUSIONS

The results of our prospective phase II study indicate that limited resection, mainly by wedge resection, is a potentially curative surgical procedure and may be an acceptable alternative to lobectomy for patients with noninvasive BAC. Furthermore, an intraoperative pathologic diagnosis of noninvasive BAC is strongly predictive and allows for an intraoperative decision to perform a limited resection in these patients.

Comparison of STIR turbo SE imaging and diffusion-weighted imaging of the lung: capability for detection and subtype classification of pulmonary adenocarcinomas

OBJECTIVE

The aim of the study was to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) for detection and subtype classification in pulmonary adenocarcinomas through comparison with short TI inversion recovery turbo spin-echo imaging sequence (STIR).

METHODS

Thirty-two patients (mean age, 65.2 years) with 33 adenocarcinomas (mean diameter, 27.6 mm) were enrolled in this study. The detection rates of both sequences were compared. The ADC values on DWI and the contrast ratio (CR) between cancer and muscle on STIR were measured and those were compared across subtype classifications. Finally, ROC-based positive tests were performed to differentiate subtype classifications, and differentiation capabilities were compared.

RESULTS

The DWI detection rate [85% (28/33)] was significantly lower than that of STIR [100% (33/33), P < 0.05]. The ADC values showed no significant difference regarding subtype classification; however, the CRs of bronchio-alveolar carcinomas (BACs) were significantly lower than those of other types (P < 0.05). When threshold values for differentiating BACs from others were adapted, the sensitivity and accuracy of DWI were significantly lower than those of STIR (P < 0.05). For differentiating adenocarcinomas with mixed subtypes from those with no BA component, there were no significant differences between the two sequences.

CONCLUSION

STIR is more sensitive for detection and subtype classification than DWI.

Commercially available computer-aided detection system for pulmonary nodules on thin-section images using 64 detectors-row CT: preliminary study of 48 cases

RATIONALE AND OBJECTIVES

Most studies of computer-aided detection (CAD) for pulmonary nodules have focused on solid nodule detection. The aim of this study was to evaluate the performance of a commercially available CAD system in the detection of pulmonary nodules with or without ground-glass opacity (GGO) using 64-detector-row computed tomography compared to visual interpretation.

MATERIALS AND METHODS

Computed tomographic examinations were performed on 48 patients with existing or suspicious pulmonary nodules on chest radiography. Three radiologists independently reported the location and pattern (GGO, solid, or part solid) of each nodule candidate on computed tomographic scans, assigned each a confidence score, and then analyzed all scans using the CAD system. A reference standard was established by a consensus panel of different radiologists, who found 229 noncalcified nodules with diameters > or = 4 mm. True-positive and false-positive results and confidence levels were used to generate jackknife alternative free-response receiver-operating characteristic plots.

RESULTS

The sensitivity of GGO for 3 radiologists (60%-80%) was significantly higher than that for the CAD system (21%) (McNemar's test, P < .0001). For overall and solid nodules, the figure-of-merit values without and with the CAD system were significantly different (P = .005-.04) on jackknife alternative free-response receiver-operating characteristic analysis. For GGO and part-solid nodules, the figure-of-merit values with the CAD system were greater than those without the CAD system, indicating no significant differences.

CONCLUSION

Radiologists are significantly superior to this CAD system in the detection of GGO, but the CAD system can still play a complementary role in detecting nodules with or without GGO.

Initial findings and progression of lung adenocarcinoma on serial computed tomography scans

OBJECTIVE

To study the initial findings of lung adenocarcinoma revealed by computed tomography (CT) scanning and observe tumor progression and elucidate appropriate follow-up schedule of tumor diagnosis via CT findings of suspected lung adenocarcinoma.

METHOD

We studied 59 patients who had undergone CT scanning twice or more at intervals of 3 months or longer before surgery. We evaluated the initial CT findings as well as all subsequent changes. The rate of tumor growth was estimated by tumor volume doubling time, using the original method of Schwartz. The histological classifications were evaluated according to the criteria of Noguchi et al (Cancer 1995;75:2844-2852).

RESULT

The initial appearances of lung adenocarcinoma were divided into 4 types: (1) ground-glass opacity-like lesions, (2) bubble-like appearance, (3) small nodules, and (4) scar-like lesions. Ground-glass opacity-like lesions tended to increase in size over the years, with solid parts appearing in some lesions during follow-up examinations. Bubble-like appearance displayed characteristic CT findings and tended to increase over the years from the time of initial diagnosis, and we therefore tended to consider them as old inflammatory lesions. Small nodules tended to increase in size over the months more rapidly than in other types. Scar-like lesions tended to exist mainly in the lungs already damaged by lung fibrosis and/or emphysema and therefore were difficult to detect on initial CT scans.

CONCLUSION

We categorized 4 types of initial findings of lung adenocarcinomas detected by CT. We determined that each type of lesion had its own unique characteristic growth patterns and required varying follow-up periods.

Doubling time of lung cancer determined using three-dimensional volumetric software: comparison of squamous cell carcinoma and adenocarcinoma

The aim of the present study was to investigate the difference in doubling time between squamous cell carcinoma (SCC) and adenocarcinoma of solid pulmonary cancer using three-dimensional volumetric software. We included 40 patients with adenocarcinoma and 11 patients with SCC, who underwent CT examinations more than once before surgical treatment. Tumor volumes and doubling times were obtained using three-dimensional volumetric computer software. Statistical analysis was performed using Mann-Whitney's U-test except for negative doubling times (doubling times less than 0 day). Negative doubling time was found in 5 of the 40 adenocarcinomas (13%), but not in any of the patients with SCC. Doubling time was beyond 400 days in 11 of the 40 adenocarcinomas (28%), but was always less than 400 days in SCC. The mean doubling time of SCC was 126+/-58 days (range, 39-221 days; median, 131 days), while that of adenocarcinomas, except for the negative doubling times, was 976+/-3134 days (range, 69-18,678 days; median, 258 days). Doubling time differed significantly between adenocarcinomas and SCC (p<0.01). In conclusion, the median doubling time of SCC lung cancers is less than that of adenocarcinomas, as measured with automated volumetric measurement software.

Pulmonary ground-glass opacity (GGO) lesions-large size and a history of lung cancer are risk factors for growth

OBJECTIVE

Ground-glass opacity (GGO) of the lung is being frequently detected by thin section computed tomography scan. However, the long term management of detected GGO is still unclear. To establish follow-up plans, we performed the clinical and radiological review to identify the factors that are closely associated with GGO growth.

METHODS

We retrospectively analyzed computed tomography images of 125 GGOs that were stable for 3 months between 1999 and 2006 at the Cancer Institute Hospital, Tokyo. To identify factors that affect the roentgenological growth, the time to GGO growth curve by Kaplan-Meyer method was evaluated in terms of gender, age, smoking, initial size, existence of a solid part, GGO density, location, multiplicity, and lung cancer history by univariate and multivariate analyses.

RESULTS

The median observation period was 1048 days (177-3269) and 26 of 125 GGOs (21%) grew. The estimated growth population for 5 years was 30%. The growth was more frequently seen in the elderly (p = 0.017), in part-solid GGO (p < 0.01) and in GGO of larger than 10 mm (p < 0.01, logrank test). By multivariate analysis, initial size (p < 0.01, Cox's model) and history of lung cancer (p = 0.017, logistic model) were independent factors that were significantly associated with GGO growth. Fifty GGOs that were 10 mm or smaller and without a lung cancer history did not grow within 3.5 years.

CONCLUSIONS

After initial management and 3 month follow-up, larger size (more than 10 mm) and a history of lung cancer are risk factors for GGO growth, and therefore should be considered when making a follow-up plan.

A new method of measuring the amount of soft tissue in pulmonary ground-glass opacity nodules: a phantom study

Objective

To devise a new method to measure the amount of soft tissue in pulmonary ground-glass opacity nodules, and to compare the use of this method with a previous volumetric measurement method by use of a phantom study.

Materials and Methods

Phantom nodules were prepared with material from fixed normal swine lung. Forty nodules, each with a diameter of 10 mm, were made with a variable mean attenuation. The reference-standard amount of soft tissue in the nodules was obtained by dividing the weight by the specific gravity. The imaging data on the phantom nodules were acquired with the use of a 16-channel multidetector CT scanner. The CT-measured amount of soft tissue of the nodules was calculated as follows: soft tissue amount = volume × (1 + mean attenuation value / 1,000). The relative percentage error (RPE) between the CT-measured amount of the soft tissue and the reference-standard amount of the soft tissue was also measured. The RPEs determined with use of the new method were compared with the RPEs determined with the current volumetric measurement method by the use of the paired t test.

Results

The CT-measured amount of soft tissue showed a strong correlation with the reference-standard amount of soft tissue (R² = 0.996, p < 0.01). The mean RPE of the CT-measured amount of soft tissue in the nodules was -7.79 ± 1.88%. The mean RPE of the CT-measured volume was 114.78 ± 51.02%,which was significantly greater than the RPE of the CT-measured amount of soft tissue (p < 0.01).

Conclusion

The amount of soft tissue measured by the use of CT reflects the reference-standard amount of soft tissue in the ground-glass opacity nodules much more accurately than does the use of the CT-measured volume.

Solitary and multiple resected adenocarcinomas after CT screening for lung cancer: histopathologic features and their prognostic implications

PURPOSE

To study the histopathologic features of CT screen-detected Stage IA adenocarcinomas to determine whether survival differed by the proportion of bronchioloalveolar component (BAC) or by the presence of multiple lesions in node-negative patients.

METHODS

Five pathologists with expertise in pulmonary pathology examined 279 resected cases of adenocarcinomas, 30 mm or less in length diagnosed by CT screening for lung cancer. The panel determined the consensus diagnosis for each case, identified additional cancers, and classified each case as solitary or non-solitary. The presence and proportion of BAC was also documented.

RESULTS

Of the cases of adenocarcinoma, 20 (7%) were BAC subtype, 246 (88%) mixed subtype and 13 (5%) adenocarcinoma-OTHER. BAC cases manifested as non-solid and part solid nodules, mixed as solid and part-solid, and other as solid only. Kaplan-Meier 10-year survival rates were 100% for BAC and adeno-MIXED with 90-99% BAC cases, 95% for mixed with 1-90% BAC, 90% for those without a BAC component, and 75% for other cases. Fifty (18%) cases were non-solitary carcinomas and 44 of these were node negative; the non-solitary node-negative cases had the same excellent prognosis as solitary node-negative cases.

CONCLUSIONS

The proportion of BAC component was a positive prognostic factor and correlated with CT consistency. Contrary to staging predictions, cases of non-solitary node-negative adenocarcinoma had the same excellent prognosis as solitary node-negative cases, suggesting that most of the small, node-negative multiple carcinomas probably represent multiple primaries rather than intrapulmonary metastasis.

Computer-aided diagnosis in lung nodule assessment

Computed tomography (CT) imaging is playing an increasingly important role in cancer detection, diagnosis, and lesion characterization, and it is the most sensitive test for lung nodule detection. Interpretation of lung nodules involves characterization and integration of clinical and other imaging information. Advances in lung nodule management using CT require optimization of CT data acquisition, postprocessing tools, and computer-aided diagnosis (CAD). The goal of CAD systems being developed is to both assist radiologists in the more sensitive detection of nodules and noninvasively differentiate benign from malignant lesions; the latter is important given that malignant lesions account for between 1% and 11% of pulmonary nodules. The aim of this review is to summarize the current state of the art regarding CAD techniques for the detection and characterization of solitary pulmonary nodules and their potential applications in the clinical workup of these lesions.

Growth rates of metastatic brain tumors in nonsmall cell lung cancer

BACKGROUND

The purpose of the study was to evaluate the growth kinetics of metastatic brain tumors during chemotherapy and to analyze growth rates and volumetric doubling time of metastatic brain tumors in patients with nonsmall cell lung cancer (NSCLC) with tumor regrowth.

METHODS

NSCLC patients with minimally symptomatic brain metastases who were not treated previously were enrolled. Serial magnetic resonance images (MRI) of 30 metastatic brain tumors in 19 patients were reviewed. Tumor growth rates and volumetric tumor doubling time of tumor regrowth were estimated. All patients were treated with front-line chemotherapy until disease progression.

RESULTS

The median tumor growth rate was 12.10 mm(3)/day (interquartile range [IQR], 3.09-36.75). The volume percentage increase/day was 1.67 (IQR, 0.69-4.59). The median volumetric tumor doubling time was 58.48 days (IQR, 32.33-98.48).

CONCLUSIONS

These findings may help optimize patient management during follow-up. Study results indicated that brain MRI should be obtained at a minimum of 2-month intervals to screen for metastatic brain tumors.

Epidermal growth factor receptor mutations in multicentric lung adenocarcinomas and atypical adenomatous hyperplasias

BACKGROUND

The mechanisms of generation and progression of multicentric lung adenocarcinoma (AD), bronchioloalveolar carcinoma (BAC), and atypical adenomatous hyperplasia (AAH) in the peripheral lung is not well known. In this study, we analyzed epidermal growth factor receptor (EGFR) mutations in the cases of multicentric AD, BAC, and AAH to reveal the role of EGFR mutation in their generations and progressions.

METHOD

Ninety-seven AAH, BAC, or AD lesions less than 3 cm in size in 26 patients were surgically resected. Of these, EGFR mutations of the nodules with the highest and the second highest grade of histologic malignancy were examined in each patient by using the peptide nucleic acid-locked nucleic acid polymerase chain reaction (PNA-LNA PCR) clamp method.

RESULTS

EGFR mutations could be examined in 48 nodules in the 26 patients. The EGFR mutations were found more frequently in lesions with higher histologic malignancy, ie, 9 of 10 ADs (90%), 16 of 28 BACs (57%), and one of 10 AAHs (10%). In 22 patients who could be examined of EGFR mutations for the two lesions in each patient, only two patients (9%) had the same mutation patterns between the two lesions, whereas 15 patients (68%) had the different statuses and the remaining five (23%) had no mutations.

CONCLUSION

Our data demonstrated that EGFR mutations seem to contribute to the acquisition of malignant potential in the AAH-AD sequence and occur independently in each lesion and in the cases of multicentric AD, BAC, and AAH.

Indolent lung cancers--time for a paradigm shift: a review

The present paradigm is that slow-growing and clinically unimportant lung cancers are very rare. Over the years, convincing evidence for their existence in significant numbers has been dismissed, but with computerized tomography scanning being increasingly common, their reality can no longer be denied. The time is now ripe for a paradigm shift--with consequences for screening as well as clinical practice in the future. The doubling time of the tumor is probably the most important factor for survival of the patient, and research on how to measure this figure is urgent. Age, smoking habits, and comorbidities of the patient are now the main factors when discussing treatment with the patient; once we can predict the behavior of the cancer, i.e., whether it is indolent or actually threatens the patient's life, we will be able to give better advice.

Lung cancer screening--comparison of computed tomography and X-ray

Recent studies on lung cancer screening with CT disclosed a discrepancy between its efficiency in detecting early lung cancer and a lack of proof for decreasing mortality from lung cancer. The present study, in a city in Japan where an X-ray screening program is provided, bi-annual CT screening was performed for X-ray screening negative subjects for 4 years. Ten patients with lung cancer were detected among 22,720 person-year subjects (0.044%) through the X-ray screening. Among the X-ray screening-negative subjects, 3305 subjects participated in a CT screening program resulting in the detection of 15 patients with lung cancer (0.454%). All 15 cases detected by CT screening and 5 of the 10 cases detected by X-ray screening were at stage IA. In respect of gender, histological type and CT findings, patients detected by CT screening had a better prognostic profile than those detected by X-ray screening. Survival was significantly better in the former than the latter, both in its entirety comparison and in a comparison limited to patients who underwent surgery. In conclusion, CT screening might have the potential to detect lung cancer with good prognostic factors not limited to early detection. Sufficiently long follow-up time, therefore, would be required to evaluate the efficacy for decreasing lung cancer mortality with CT screening.

Diagnostic accuracy of CT-guided core biopsy of ground-glass opacity pulmonary lesions

OBJECTIVE

The purpose of our study was to evaluate the accuracy of CT-guided percutaneous core biopsy of ground-glass opacity (GGO) pulmonary lesions.

MATERIALS AND METHODS

The study included 50 patients (24 men, 26 women; age range, 43-78 years) who had a GGO pulmonary lesion and underwent CT-guided core biopsy. Diagnostic accuracy was compared between two groups according to lesion size (< 2 cm vs > or = 2 cm) and GGO component (> 90% vs 50-90%). Each case was reviewed for complications, including pneumothorax, thoracostomy tube insertion, and hemoptysis.

RESULTS

Malignancy was finally diagnosed in 33 patients, including three who underwent repeated biopsies, with 33 true-positive and three false-negative findings for an overall sensitivity of 92% (33/36). A benign lesion was finally diagnosed in 10 patients with one false-positive result, for a specificity of 90%. Two benign lesions without confirmative diagnosis because of loss of follow-up and five nondiagnostic samples were excluded from the calculations of sensitivity, specificity, and diagnostic accuracy. The overall diagnostic accuracy was 91%, with a positive predictive value of 97% and a negative predictive value of 75%. Sensitivity and accuracy were not significantly different between the two groups of lesion size and GGO components (p = 0.0491). Ten (18%) patients had pneumothorax, with one (2%) requiring placement of a thoracostomy tube. Mild hemoptysis occurred in seven (13%) patients.

CONCLUSION

CT-guided core biopsy of GGO lesions can yield high diagnostic accuracy and acceptable complication rates approaching those of solid lesions.

Pulmonary adenocarcinomas with ground-glass attenuation on thin-section CT: Quantification by three-dimensional image analyzing method

PURPOSE

The purpose of this study was to evaluate software designed to calculate whole tumor volumes and the ratio of the solid component to whole volume (%solid) in pulmonary nodules with ground-glass opacity in three dimensions.

METHODS

The study included 49 patients with histologically diagnosed adenocarcinomas smaller than 2 cm in diameter. The %solid was calculated both automatically using new software, and by manual measurement of the following four parameters by two observers: the ratio of the largest diameter (a) and the area (b) at the mediastinal window to those at the lung window, and the ratio of the largest diameter (c) and the area (d) of the solid component to those of the ground-glass component at the lung window. Agreement of intra- and inter-observer data by both Spearman's rank correlation test and Bland-Altman's method, and a comparison by Spearman's rank correlation test of the %solid in both Noguchi sub-classifications and vessel invasion in histologic specimens, between the software and manual methods, were assessed.

RESULTS

Of the 49 nodules, 48 were successfully measured and assessed. The agreement of the observers with the software was better (Bland-Altman's method; mean difference, -0.3%; 95% limits of agreement, -3.1 to 2.5%) than with the manual measurements (a: 5.3%, -17.6 to 28.3%; b: 8.3%, -10.6 to 26.9%; c: 10.7%, -17.6 to 39%; d: 6.4%, -22 to 34.8%). The correlation between %solid and the histological group was worse with the software (Spearman's rank correlation test; r=0.487, p<0.001) than with the manual method (a, r=0.534; b, r=0.557; c, r=0.552; d, r=0.545).

CONCLUSION

Although the software requires improvement in the calculation of %solid with volumetric analysis, this is a reproducible and promising quantitative method for determining the grades of malignancy of small lung cancers.

Stepwise progression from ground-glass opacity towards invasive adenocarcinoma: long-term follow-up of radiological findings

The natural history of lung adenocarcinoma with ground-glass opacity (GGO) remains undetermined. We describe a lung adenocarcinoma in which GGO transformed through a scar-like lesion over the long term into a solid nodule of poorly differentiated adenocarcinoma. Whether poorly differentiated lung adenocarcinoma can evolve from GGO-type adenocarcinoma is an important issue that requires clarification.

Lung lesion doubling times: values and variability based on method of volume determination

PURPOSE

To determine doubling times (DTs) of lung lesions based on volumetric measurements from thin-section CT imaging.

METHODS

Previously untreated patients with > or = two thin-section CT scans showing a focal lung lesion were identified. Lesion volumes were derived using direct volume measurements and volume calculations based on lesion area and diameter. Growth rates (GRs) were compared by tissue diagnosis and measurement technique.

RESULTS

54 lesions were evaluated including 8 benign lesions, 10 metastases, 3 lymphomas, 15 adenocarcinomas, 11 squamous carcinomas, and 7 miscellaneous lung cancers. Using direct volume measurements, median DTs were 453, 111, 15, 181, 139 and 137 days, respectively. Lung cancer DTs ranged from 23-2239 days. There were no significant differences in GRs among the different lesion types. There was considerable variability among GRs using different volume determination methods.

CONCLUSIONS

Lung cancer doubling times showed a substantial range, and different volume determination methods gave considerably different DTs.

Evidence for the Treatment of Patients With Pulmonary Nodules: When Is It Lung Cancer?

BACKGROUND

The solitary pulmonary nodule (SPN) is a frequent incidental finding that may represent primary lung cancer or other malignant or benign lesions. The optimal management of the SPN remains unclear.

METHODS

We conducted a systematic literature review to address the following questions: (1) the prevalence of SPN; (2) the prevalence of malignancy in nodules with varying characteristics (size, morphology, and type of opacity); (3) the relationships between growth rates, histology, and other nodule characteristics; and (4) the performance characteristics and complication rates of tests for SPN diagnosis. We searched MEDLINE and other databases and used previous systematic reviews and recent primary studies.

RESULTS

Eight large trials of lung cancer screening showed that both the prevalence of at least one nodule (8 to 51%) and the prevalence of malignancy in patients with nodules (1.1 to 12%) varied considerably across studies. The prevalence of malignancy varied by size (0 to 1% for nodules < 5 mm, 6 to 28% for nodules 5 to 10 mm, and 64 to 82% for nodules > 20 mm). Data from six studies of patients with incidental or screening-detected nodules showed that the risk for malignancy was approximately 20 to 30% in nodules with smooth edges; in nodules with irregular, lobulated, or spiculated borders, the rate of malignancy was higher but varied across studies from 33 to 100%. Nodules that were pure ground-glass opacities were more likely to be malignant (59 to 73%) than solid nodules (7 to 9%). The sensitivity of positron emission tomography imaging for identifying a malignant SPN was consistently high (80 to 100%), whereas specificity was lower and more variable across studies (40 to 100%). Dynamic CT with nodule enhancement yielded the most promising sensitivity (sensitivity, 98 to 100%; specificity, 54 to 93%) among imaging tests. In studies of CT-guided needle biopsy, nondiagnostic results were seen approximately 20% of the time, but sensitivity and specificity were excellent when biopsy yielded a specific benign or malignant result.

CONCLUSIONS

The prevalence of an SPN and the prevalence of malignancy in patients with an SPN vary widely across studies. The interpretation of these variable prevalence rates should take into consideration not only the nodule characteristics but also the population at risk. Modern imaging tests and CT-guided needle biopsy are highly sensitive for identifying a malignant SPN, but the specificity of imaging tests is variable and often poor.

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.

Differential diagnosis of ground-glass opacity nodules: CT number analysis by three-dimensional computerized quantification

OBJECTIVES

To differentiate among atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and adenocarcinoma showing ground-glass opacity (GGO) on CT scans, we conducted a study to determine the optimal parameter on CT number analysis using three-dimensional (3D) computerized quantification.

METHODS

From the CT numbers of GGO lesions obtained by 3D computerized quantification, CT number histogram pattern, peak CT number on the histogram, mean CT number, and the 5th to 95th percentile CT numbers were analyzed to determine the optimal parameter for differentiation among AAH (n = 10), BAC (n = 21), and adenocarcinoma (n = 12).

RESULTS

While the CT number histogram showed one peak in all 10 of the AAH lesions (100%), it showed two peaks in 8 of 21 BAC lesions (38%), and in 5 of 12 adenocarcinoma lesions (42%). For differentiation between AAH and BAC, the 75th percentile CT number with a cutoff value of -584 Hounsfield units (HU) was optimal, with a sensitivity of 0.90 and a specificity of 0.81. For differentiation between BAC and adenocarcinoma, a mean CT number with a cutoff value of -472 HU was optimal, with a sensitivity of 0.75 and a specificity of 0.81.

CONCLUSIONS

From the analysis of CT numbers of GGO lesions obtained by 3D computerized quantification, we conclude the following: (1) two peaks on the CT number histogram can rule out AAH; (2) the 75th percentile is the optimal CT number for differentiating between AAH and BAC; and (3) the mean CT number is the optimal CT number for differentiating between BAC and adenocarcinoma.

Nodular ground-glass opacities on thin-section CT: size change during follow-up and pathological results

OBJECTIVE

To evaluate the inter-group differences in growth and the pathological results of nodular ground-glass opacities (GGOs) according to their size and focal solid portions.

MATERIALS AND METHODS

Ninety-six nodular GGOs in 55 individuals followed by CT for at least one month from an initial chest CT were included. Forty nodular GGOs in 30 individuals were pathologically confirmed to be: adenocarcinoma (n = 15), bronchioloalveolar carcinoma (BAC) (n = 11), atypical adenomatous hyperplasia (AAH) (n = 8), focal interstitial fibrosis (n = 5) and aspergillosis (n = 1). Lesions were categorized based on high-resolution CT findings: pure nodular GGO (PNGGO) < or = 10 mm, PNGGO > 10 mm, mixed nodular GGO (MNGGO) < or = 10 mm, and MNGGO > 10 mm. In each group, the change in size during the follow-up period, the pathological results and the rate of malignancy were evaluated.

RESULTS

Three MNGGO lesions, and none of the PNGGO, grew during the follow-up period. Resected PNGGOs < or = 10 mm were AAH (n = 6), BAC (n = 5), and focal interstitial fibrosis (n = 1). Resected PNGGOs > 10 mm were focal interstitial fibrosis (n = 4), AAH (n = 2), BAC (n = 2), and adenocarcinoma (n = 2). Resected MNGGOs < or = 10 mm were adenocarcinoma (n = 2), and BAC (n = 1). Resected MNGGOs > 10 mm were adenocarcinoma (n = 11), BAC (n = 3), and aspergillosis (n = 1).

CONCLUSION

Mixed nodular GGOs (MNGGOs) had the potential for growth; most were pathologically adenocarcinoma or BAC. By contrast, PNGGOs were stable for several months to years; most were AAH, BAC, or focal interstitial fibrosis.

Impalpable pulmonary nodules with ground-glass opacity: Success for making pathologic sections with preoperative marking by lipiodol

BACKGROUND

The developments in high-resolution CT scanning have increased the chance of detecting small bronchioloalveolar carcinoma (BAC) or atypical adenomatous hyperplasia (AAH) that appears as a ground-glass opacity (GGO). However, these lesions are not only difficult to localize during surgery, but they are also hard to make pathologic sections of because they are usually impalpable. Here, we report a method of making pathologic sections for impalpable GGO lesions.

METHODS

Twenty-nine impalpable GGO lesions < 1 cm in size were marked by 0.4 to 0.5 mL of lipiodol under CT scan before surgery. The lesions were resected under C-arm fluoroscopy. The radiopaque areas marked by lipiodol within the formalin-fixed specimens were cut serially under conventional fluoroscopy for pathologic examinations.

RESULTS

The mean (+/- SD) size of the lesions was 0.5 +/- 0.2 cm (range, 0.2 to 1 cm), and the mean depth from the pleural surface was 1.6 +/- 1.4 cm (range, 0.2 to 6 cm). The mean number of sections submitted for pathologic examinations was 2.3 +/- 1.7 per lesion (range, 1 to 7 per lesion). While 11 of the 29 lesions (38%) were invisible even on the cut surface of the specimens, all were demonstrated in hematoxylin-eosin sections. The pathologic diagnosis was BAC in 17 lesions, AAH in 10 lesions, and organized pneumonia in 2 lesions. The use of lipiodol did not affect the pathologic findings.

CONCLUSIONS

The use of fluoroscopy to cut sections from resected specimens after preoperative marking with lipiodol was useful for making pathologic sections of impalpable GGOs < 1 cm in size.

Nodular Ground-Glass Opacity at Thin-Section CT: Histologic Correlation and Evaluation of Change at Follow-up

The popularization of computed tomography (CT) in clinical practice and the introduction of mass screening for early lung cancer with the use of CT have increased the frequency of findings of subtle nodules or nodular ground-glass opacity. Nodular ground-glass opacity may be observed in malignancies such as bronchioloalveolar carcinoma and adenocarcinoma, as well as in their putative precursors, such as atypical adenomatous hyperplasia. Nodular ground-glass opacity also may be seen in the presence of benign conditions, including focal interstitial fibrosis, inflammation, and hemorrhage. The persistence of nodular ground-glass opacity over time may be strongly suggestive of an early-stage malignancy, especially if the lesion increases in size or includes a solid component that increases in its extent. Persistent nodular ground-glass opacity also may remain stable in size but show increased attenuation. The more extensive the solid portions of the lesion, the higher the probability of malignancy and the poorer the prognosis. An awareness of the clinical setting, in addition to familiarity with the thin-section CT features of nodular ground-glass opacity at initial and follow-up imaging over several months, can help identify malignancy and achieve an accurate diagnosis. A meticulous evaluation of those CT features, and their correlation with specific histopathologic characteristics, also may enable a more accurate prognosis in cases of neoplastic disease.

Comparison of pathologic findings of baseline and annual repeat cancers diagnosed on CT screening

Screening for lung cancer produces two groups of lung cancers. Baseline cases include all prevalent cases with the expectation that slower-growing cancers and those that have achieved higher stage will be found in greater frequency. Repeat examination is expected to detect those cancers which have crossed the threshold for detection during the screening interval - 1 year in this study - and these are typically more rapidly growing cancers. The two groups encompass the full spectrum of lung cancers. Comparison of the baseline and annual repeat cases revealed differences in types of lung cancer. There were 202 baseline-detected cancers spanning the spectrum of pulmonary neoplasms with some slowly growing, some rapidly progressive and some at high stage; the 48 annual repeat cancers also included a spectrum of lung cancers but with more of the rapidly growing types, and more closely approximated the clinical spectrum of lung cancers. The NE carcinomas showed this trend best; small-cell carcinomas were under-represented and typical carcinoids were only found in the baseline group. Repeat cancers were found to grow rapidly, were typically smaller, less often multiple and the adenocarcinomas were less often pure BAC and less frequently contained a BAC component when invasive. The baseline adenocarcinomas included most of the BAC's, which is a diagnosis that requires special attention to its WHO definition. AAH was found to be frequently associated with adenocarcinoma, particularly BAC. Both baseline and annual repeat cases had a high percentage of invasive carcinomas with comparably high rates of resectability, high rates of node negativity and consequently a high proportion of cases in low stage.

Prognostic significance of a histologic subtype in small adenocarcinoma of the lung: the impact of nonbronchioloalveolar carcinoma components

BACKGROUND

We tried to clarify whether the histologic subtypes and the size of the solid component of an adenocarcinoma are more important predictive factors for invasiveness or prognosis than is total tumor size, even in lung adenocarcinomas that were 2 cm or smaller.

METHODS

Between 1996 and December 2005, after standard surgical treatment, 82 patients were diagnosed as having adenocarcinoma with a maximum diameter of 2 cm or less. The group comprised 37 females and 45 males, with ages ranging from 41 to 80 years (median, 64). The clinicopathologic records of the patients were examined with regard to age, sex, nodal status, tumor size (largest diameter of the total tumor as well as the largest diameter without the bronchioloalveolar carcinoma [BAC] component [solid component]), serum carcinoembryonic antigen level, and histologic type. These variables were analyzed as risk factors for vascular or lymphatic invasion, lymph node metastasis, and prognosis. Histologic subtype was classified into two groups: mixed BAC (mixed adenocarcinoma with BAC) and minimal or non-BAC (tumors with little or no BAC component).

RESULTS

Histologic subtype was a significant predictive factor both for invasiveness (vascular or lymph vessels) and lymph node metastasis, in both univariate and multivariate analysis. Tumor diameter was not a significant factor in either univariate or multivariate analysis (p = 0.28, 0.15, respectively). However, diameter excluding the BAC component was a significant factor for invasiveness in mixed BAC type (p = 0.035), whereas total diameter was not significant (p = 0.28). Finally, histologic subtype and lymph node metastasis were significant prognostic factors for survival in both univariate (p = 0.03, 0.05, respectively) and multivariate (p = 0.04, 0.05, respectively) analyses. The 5-year survival rate was 94.4% (94.1% for pN0) for the mixed BAC type and 71.4% (78.7% for pN0) for the minimal or non-BAC type (p = 0.009; p = 0.04 for pN0 nodes).

CONCLUSIONS

Small adenocarcinomas can be classified into two categories. The first category is a minimal or non-BAC adenocarcinoma that shows aggressive biological behavior. The second category is a mixed BAC, which demonstrates less invasive or aggressive biological behavior than the minimal or non-BAC type, with the degree of invasiveness being associated with the size of the non-BAC component.

Solitary Pulmonary Nodules: Detection, Characterization, and Guidance for Further Diagnostic Workup and Treatment

OBJECTIVE

The purpose of our study is to improve radiologists' understanding of the clinical issues involved in making a diagnosis and to guide further diagnostic workup and treatment of solitary pulmonary nodules (SPNs).

CONCLUSION

Information on the morphologic and hemodynamic characteristics of SPNs provided by dynamic helical CT, with high specificity and reasonably high accuracy, can be used for initial assessment. PET/CT is more sensitive at detecting malignancy than dynamic helical CT, and all malignant nodules may be potentially diagnosed as malignant by both techniques. Therefore, PET/CT may be selectively performed to characterize SPNs that show indeterminate results at dynamic helical CT.

Management of an incidentally discovered pulmonary nodule

The incidental finding of a pulmonary nodule on computed tomography (CT) is becoming an increasingly frequent event. The discovery of such a nodule should evoke the possibility of a small bronchogenic carcinoma, for which excision is indicated without delay. However, invasive diagnostic procedures should be avoided in the case of a benign lesion. The objectives of this review article are: (1) to analyze the CT criteria defining benign nodules, nodules of high suspicion of malignancy and indeterminate nodules, (2) to analyze the diagnostic performances and limitations of complementary investigations requested to characterize indeterminate lung nodules, (3) to review the criteria permitting to assess the probability of malignancy of indeterminate nodules and (4) to report on the new guidelines provided by the Fleischner Society for the management of small indeterminate pulmonary nodules, according to their prior probability of malignancy.

Distribution of stage I lung cancer growth rates determined with serial volumetric CT measurements

PURPOSE

To retrospectively determine the distribution of stage I lung cancer growth rates with serial volumetric computed tomographic (CT) measurements.

MATERIALS AND METHODS

This study was institutional review board approved and HIPAA compliant. The informed consent requirement was waived. Patients (n = 149) with stage I lung cancer who underwent two pretreatment CT examinations 25 or more days apart were identified. At the first and last examinations, tumor perimeters were manually inscribed by using software tools and the cross-sectional area was calculated. To calculate tumor volume, the summed areas were multiplied by the section increment and a formula was applied to reduce partial volume effects. Doubling time (DT) was calculated by using the volume and interscanning interval. The percentages of tumors that would surpass volume increase thresholds of 5%-25% for detectable growth at different time intervals were calculated. Age at diagnosis was compared with the reciprocal of DT, time interval between CT examinations, and initial tumor volume by using Pearson correlation. P < .05 denoted statistical significance.

RESULTS

Lung cancer was stage IA in 99 patients and stage IB in 50. Median patient age was 72 years, and median interscanning interval was 130 days. Median tumor volumes were 3000 and 6213 mm3 at the first and last examinations, respectively. Median DT was 207 days; 21 tumors did not increase in volume between examinations. The interscanning interval required for 90% of growing tumors to surpass the growth threshold ranged from 8 weeks (5% threshold) to 37 weeks (25% threshold). Fifty-three percent of growing tumors would surpass the 25% threshold at 8 weeks, and 95% would surpass it at 1 year. Age at diagnosis was negatively correlated with growth rate (P = .047); there was no correlation between growth rate and either age at diagnosis or interscanning interval.

CONCLUSION

At serial volumetric CT measurements, there was wide variability in growth rates. Some biopsy-proved cancers decreased in volume between examinations.

Early detection and chemoprevention of lung cancer

Lung cancer is the most common cause of cancer death worldwide with more than 1.3 million people dying of the disease annually. While antitobacco initiatives in young people are important in preventing lung cancer in the long term, additional measures such as early detection and chemoprevention are needed for individuals already at risk due to past exposure to tobacco smoke. This review highlights the potential use of sputum, exhaled breath and blood biomarkers as well as thoracic CT and autofluorescence bronchoscopy for early detection. The current status of chemoprevention is summarized. The case for using a two-step screening strategy is also discussed.

Estimated impact of LDCT-identified stage IA non-small-cell lung cancer on screening efficacy

About one-third of individuals radiographically diagnosed with surgical-pathological stage IA non-small-cell lung cancer (IA-NSCLC) harbor occult metastases that prove lethal. A comparison of the projected outcome of CT-diagnosed IA-NSCLC with actuarial figures for life expectancy of screenees suggests that about half of the remainder will succumb to alternative causes. CT screening can be efficacious if and only if it leads to an interdiction of potentially lethal cancers in the remaining one-third of sufficient magnitude that it offsets the surgical mortality and abbreviation of life expectancy in the two-thirds who are either understaged or overdiagnosed. Preliminary evidence from CT screening trials fails to support the premise that it diminishes the absolute number of advanced lung cancers.

The solitary pulmonary nodule

The imaging evaluation of a solitary pulmonary nodule is complex. Management decisions are based on clinical history, size and appearance of the nodule, and feasibility of obtaining a tissue diagnosis. The most reliable imaging features are those that are indicative of benignancy, such as a benign pattern of calcification and periodic follow-up with computed tomography for 2 years showing no growth. Fine-needle aspiration biopsy and core biopsy are important procedures that may obviate surgery if there is a specific benign diagnosis from the procedure. In using the various imaging and diagnostic modalities described in this review, one should strive to not only identify small malignant tumors--where resection results in high survival rates--but also spare patients with benign disease from undergoing unnecessary surgery.

CT screening for lung cancer: significance of diagnoses in its baseline cycle

PURPOSE

The aim of this study was to assess the significance of Stage I diagnoses of lung cancer in the baseline cycle of screening for this disease, with special reference to the potential for overdiagnosis.

METHODS

We reviewed all 69 cases of Stage I lung cancer diagnosis resulting from our baseline CT screening. Among these 69 cases of lung cancer, 24 presented as solid, 30 as part-solid, and 15 as nonsolid nodules. The extent to which these represented genuine malignancy was assessed by a panel of experts on lung pathology, and the "aggressiveness" of these cases was addressed by the criterion of the tumor's volume doubling time being less than 400 days.

RESULTS

The expert panel confirmed all 69 cases as representing genuine malignancy. Among the 69 cases without evidence of metastases, the proportion that satisfied the aggressiveness criterion was 60/69=87%. The corresponding proportions by presentation as solid, part-solid, and nonsolid nodule were 23/24 (96%), 27/30 (90%), and 10/15 (67%), respectively.

CONCLUSIONS

In baseline CT screening for lung cancer, overdiagnosis of the disease is uncommon, with cases presenting as a nonsolid nodule a possible exception to this.

Tumor staging using whole-body high-resolution 16-channel PET-CT: does additional low-dose chest CT in inspiration improve the detection of solitary pulmonary nodules?

For optimal image fusion between CT and F-18-FDG-PET, the acquisition of CT images is performed in mild expiratory suspension, which might compromise the detection of lung metastases. This study aimed at evaluating the influence of expiration on the detection of solitary pulmonary nodules (SPN) and at assessing if additional inspiratory low-dose CT (I-LDCT) of the chest can improve the detection of potential lung metastases performing whole-body 16-channel PET-CT. Sixty-six patients with malignant tumors underwent PET-CT: contrast-enhanced CT was acquired during mild expiration and was used for fusion with PET images; additionally, chest I-LDCT was performed at deep inspiration. Two radiologists reported all SPN detected at I-LDCT and the expiratory CT scan independently. Overall, 53% of 128 SPN (mean: 3.8+/-0.2 mm) were detected at both respiratory states: 51 SPN only at I-LDCT, and 9 nodules only at expiratory CT. Of the SPN, 117/128 were classified as certain; 45 of those were additionally detected at I-LDCT, and 6 nodules at expiratory CT. A 100% detection rate was reached in SPN >4 mm at I-LDCT versus >8 mm at expiratory CT (all P<0.001). Additional I-LDCT of the chest significantly improves the detection of SPN at whole-body F-18-FDG-PET-CT and thus is recommended as part of the standard protocol for oncological patients.