Computed tomography for evaluation of mediastinal lymph nodes in lung cancer: correlation with surgical staging

Pulmonologist's Road Map to Mediastinal Lymph Node Imaging

Mediastinal lymph node station maps are intended to facilitate nodal staging in patients with non-small cell lung cancer. These maps have been revised over time and the International Association for Study of Lung Cancer (IASLC) map is the latest rendition. This article illustrates the imaging appearance of each of the IASLC map mediastinal lymph node stations, overviews some of the mediastinal lymph node sampling techniques, and discusses common pitfalls of the IASLC map. It also reviews mediastinal anatomic variants and pathologic features that may simulate lymphadenopathy.

Computed tomography and cross-sectional anatomy of the thorax in clinically normal dogs

OBJECTIVE

To provide a detailed anatomic description of the thorax in clinically normal dogs by means of computed tomography.

ANIMALS

4 clinically normal adult German Shepherd Dogs weighing 28 to 37 kg.

PROCEDURE

Dogs were anesthetized and positioned in ventral recumbency for computed tomographic (CT) examination of the thorax. A CT image from the thoracic inlet to the diaphragm was made by use of a third-generation scanner with a slice thickness of 5 mm. Individual images were reviewed by use of soft tissue (window width, 250 Hounsfield units; window level, 35 Hounsfield units) and lung (window width, 1,000 Hounsfield units; window level, -690 Hounsfield units) settings. One dog, weighing 28 kg, was euthanatized, bound on a wooden frame in the same position as used for CT examination, and frozen at -14 degrees C until solid. By use of an electric band saw, the frozen thorax was sectioned at 10-mm-thick intervals. Slab sections were immediately cleaned, photographed, and compared with corresponding CT images.

RESULTS

Anatomic sections were studied, and identified anatomic structures were matched with structures on corresponding CT images. Except for some blood vessels and details of the heart, most of the bony and soft tissue structures of the thorax discerned on anatomic slices could be found on matched CT images.

CONCLUSIONS AND CLINICAL RELEVANCE

Because CT images provide detailed information on most structures of the canine thorax, results of our study could be used as a guide for evaluation of CT images of the thorax of dogs with thoracic diseases.

Combined procedures for mediastinal staging in non-small cell lung cancer

We investigated whether the combined use of computed tomography, thallium-201 single photon emission computed tomography and serum carcinoembryonic antigen level improves preoperative non-invasive mediastinal. 128 consecutive non-small cell lung cancer patients (85 adenocarcinomas, 31 squamous cell carcinomas and 12 others) who underwent a surgical resection were enrolled in this study. The results of the combined procedures were compared with the pathologic findings. Our results showed that the combined evaluation of mediastinal nodal involvement with the three procedures might increase underestimation, but decrease overestimation as compared to computed tomography alone. Thallium-201 single photon emission computed tomography for patients with enlarged nodes at computed tomography showed 81.3% and 100% of positive predictive value in overall and squamous cell carcinoma patients, respectively. The negative predictive value of thallium-201 single photon emission computed tomography for patients without enlarged nodes at computed tomography was highly accurate in adenocarcinoma (93.9%) as well as squamous cell carcinoma (94.4%). Combining computed tomography findings and serum carcinoembryonic antigen level had a poor predictive value. However, in patients with adenocarcinoma, a negative examination was highly accurate (95.2%). In conclusion, our results show a trend that combined use of the three procedures might improve non-invasive mediastinal staging in non-small cell lung cancer.

Prognostic impact of VEGF, CD31, CD34, and CD105 expression and tumour vessel invasion after radical surgery for IB-IIA non-small cell lung cancer

AIMS

To evaluate the prognostic impact of tumour angiogenesis assessed by vascular endothelial growth factor (VEGF), microvessel density (MVD), and tumour vessel invasion in patients who had undergone radical resection for stage IB-IIA non-small cell lung cancer (NSCLC).

METHODS

Fifty one patients (42 men, nine women; mean age, 62.3 years; SD, 6.9) undergoing complete surgical resection (35 lobectomy, 16 pneumonectomy) of pathological stage IB (n = 43) and IIA (n = 8) NSCLC were evaluated retrospectively. No patient underwent postoperative chemotherapy or neoadjuvant treatment. Tumour specimens were stained for VEGF and specific MVD markers: CD31, CD34, and CD105.

RESULTS

VEGF expression significantly correlated with high CD105 expression (p < 0.0001) and tumour vessel invasion (p = 0.04). Univariate analysis showed that those patients with VEGF overexpression (p = 0.0029), high MVD by CD34 (p = 0.0081), high MVD by CD105 (p = 0.0261), and tumour vessel invasion (p = 0.0245) have a shorter overall survival. Furthermore, multivariate Cox regression analysis showed that MVD by CD34 (p = 0.007), tumour vessel invasion (p = 0.024), and VEGF expression (p = 0.042) were significant predictive factors for overall survival. Finally, the presence of both risk factors, tumour vessel invasion and MVD by CD34, was highly predictive of poor outcome (odds ratio, 3.4; 95% confidence interval, 1.7 to 6.5; p = 0.0002).

CONCLUSIONS

High MVD by CD34 and tumour vessel invasion are more closely related to poor survival than the other neoangiogenetic factors in stage IB-IIA NSCLC. This may be because these factors are more closely related to the metastatic process.

Cost-effectiveness associated with the diagnosis and staging of non-small-cell lung cancer

OBJECTIVE

We evaluated how much time and money could be saved without compromising overall results in treating lung cancer.

SUBJECTS AND METHODS

We retrospectively evaluated 318 patients for T- and M-factors and 335 for N-factor. If bronchoscopy failed to diagnose a mass lesion believed to be malignant in x-ray computed tomography (CT), we proceeded to direct thoracotomy without needle or video-assisted biopsy. When mediastinal nodes were negative in CT, we proceeded to direct thoracotomy without mediastinoscopy. We searched routinely for distant metastasis with brain and abdominal CTs and bone scans.

RESULTS

Lesions suspected of malignancy in CT were pathologically malignant in 93%. A total of 82.8% of patients with CT-negative mediastinum were without metastasis. The remainder, with metastasis, had a postoperative 5-year survival of 23.5%. Brain CT scans were positive in only 2.2%, abdominal CT scans in 2.4%, and bone scans in 5.0%, for patients with a cT1/T2 non-cN2 lesion.

CONCLUSION

Brain and abdominal CT scans and bone scans may be omitted for cT1/T2 and non-cN2 lesions in CT. CT-negative mediastinum then leads to direct thoracotomy. The vast majority of patients may thus undergo surgery earlier with less physical and financial burden. The cost saving was calculated to be 59.4% per cT1/T2 non-cN2 patient, or US$666,815, for population evaluated based on cost-effectiveness.

The role of computed tomographic scanning in diagnosing mediastinal node involvement in non-small cell lung cancer

OBJECTIVES

The reliability of computed tomographic scanning in evaluating mediastinal node involvement is controversial because of the high false result rate. We attempted to identify significant factors responsible for false-positive and false-negative scans.

METHODS

From August 1992 through April 1997, 401 patients with lung cancer who underwent major lung resection and systematic lymph node dissection were enrolled in this study. We retrospectively examined mediastinal node size, tumor location, maximum tumor dimension, the presence or absence of obstructive pneumonia, atelectasis, pulmonary fibrosis, and lymph node calcification on contrast-enhanced computed tomographic scans. We identified clinical and radiologic factors responsible for the false results by using univariate and multivariable analysis.

RESULTS

Central tumor location proved to be a significant factor of false-positive scans. Elevated carcinoembryonic antigen level and larger tumor dimension were significant factors of false-negative scans. In patients with a peripheral tumor smaller than 40 mm and normal levels of serum carcinoembryonic antigen, sensitivity, specificity, positive predictive value, and negative predictive value were 6%, 93%, 8%, and 90%, respectively. The reliability of computed tomographic scanning in this low-risk subgroup was high in detecting N0-1 disease but low in diagnosing N2 disease.

CONCLUSION

It is not possible to accurately diagnose N2 disease by using lymph node size on computed tomographic scanning alone, especially in patients with a central tumor, an elevated serum carcinoembryonic antigen level, or a tumor of 40 mm or larger. A preoperative invasive staging procedure is indicated in these populations and may not be indicated in the population with normal computed tomographic scan results without any of these risk factors.

Clinical predictors of N2 disease in non-small cell lung cancer

OBJECTIVES

To identify clinical or radiologic predictors of mediastinal lymph node involvement in patients with non-small cell lung cancer, and to define the indications of preoperative mediastinoscopy.

METHODS

From August 1992 through April 1997, 387 patients with lung cancer (290 adenocarcinoma and 97 squamous cell carcinoma) underwent surgical resection. We retrospectively measured all mediastinal lymph node sizes both in the shortest and longest axes on contrast-enhanced CT scan to determine the optimal size criteria. Using multivariate logistic regression analysis, we identified clinical or radiologic predictors of N2 disease.

RESULTS

We could not identify reliable size criteria for nodal involvement. We found two significant predictive factors of N2 disease on the basis of multivariable analysis: maximum tumor dimension and serum carcinoembryonic antigen (CEA) concentrations. The lymph node size did not prove to be a significant factor. Among 50 patients with serum CEA concentrations < 5.0 ng/mL and maximum tumor dimension < 20 mm, pathologic N2 disease was proven only in three patients (6%), regardless of the lymph node size on CT scan. Among 140 patients with serum CEA concentrations > or = 5.0 ng/mL and maximum tumor dimension > or = 20 mm, approximately one third (n = 46) showed N2 disease.

CONCLUSION

Serum CEA concentrations and maximum tumor dimension were more valuable in predicting N2 disease than the lymph node size on CT scan. Mediastinoscopy is indicated in patients with serum CEA concentrations > or = 5.0 ng/mL and maximum tumor dimension > or = 20 mm, and not indicated in patients with serum CEA concentrations < 5.0 ng/mL and maximum tumor dimension < 20 mm.

PET, CT, and MRI with Combidex for mediastinal staging in non-small cell lung carcinoma

BACKGROUND

To determine the relative utility of positron emission tomography (PET), computed tomography (CT), and magnetic resonance imaging with Combidex (MRI-C) in the non-invasive staging of non-small cell lung cancer (NSCLC) mediastinal lymph nodes (MLN), we compared the three tests' individual performance with surgical mediastinal sampling. In contrast to prior studies, cytology was not used.

METHODS

The MLN were evaluated using PET and CT in 64 NSCLC patients. MRI-C was performed in 9 of these patients. MLN with a PET standard uptake value greater than or equal to 2.5, or greater than 1 cm in the short axis by CT or lack of MRI-C signal change were considered positive for metastatic disease. All MLN were sampled and subjected to standard pathologic analysis. PET, CT, and MRI-C scans were interpreted blinded to the histopathological results. Sensitivity, specificity, and accuracy for each scan type to appropriately stage MLN was determined using pathologic results as the standard.

RESULTS

Thirty patients had stage I disease, 8 stage II, 9 stage IIIA, 7 stage IIIB, and 10 stage IV. Two-hundred-and-thirty MLN were sampled. Sixteen patients had metastatic mediastinal disease. Compared to the pathological results, PET, CT, and MRI-C had a sensitivity, specificity, and accuracy of 70%, 86%, 84%; 65%, 79%, 76%; 86%, 82%, and 83%, respectively. PET and MRI-C were statistically more accurate than CT (p<0.001). In cases where PET and CT did not identify MLN involvement with NSCLC, 8% (2/25) were pathologically positive.

CONCLUSIONS

PET and MRI-C are statistically more accurate than CT. However, the differences are small and may not be clinically relevant. No technique was sensitive or specific enough to change the current recommendation to perform mediastinoscopy for MLN staging in NSCLC.

Mediastinal staging in non-small-cell lung cancer

Decision analysis was used to study the approach to staging mediastinal involvement in patients with non-small-cell lung cancer (NSCLC). Various diagnostic strategies for mediastinal disease staging using computed tomography (CT), mediastinoscopy, and bronchoscopy with transbronchial needle aspiration (TBNA), either individually or in series, were compared and found to result in similar patient life expectancies. Two strategies, one using bronchoscopy and TBNA alone and the other using it in combination with CT, were consistently least expensive across a wide range of prior probabilities, test characteristics, and charges. The authors conclude that strategies for staging mediastinal involvement in NSCLC that rely on bronchoscopy and TBNA are preferable because they are least expensive.

Isolated pulmonary nodules in head and neck cancer patients

Not infrequently, a patient with newly diagnosed head and neck cancer is noted on preoperative chest radiography to have a solitary pulmonary nodule. It is initially unclear whether the pulmonary nodule is a benign lesion or a metastatic or primary lung malignancy. Considerable controversy exists regarding the evaluation of such patients as well as the treatment, assuming that the pulmonary lesion is malignant. We have reviewed the UCLA experience with patients who had head and neck cancers and pulmonary cancers no more than 5 years apart, and reviewed the literature on early stage lung cancer. We present a rational approach to the workup and treatment of patients with head and neck cancer and a pulmonary nodule on chest radiography.

The role of surgery in N2 lung cancer

Whereas most physicians believe that long-term survival is unlikely when mediastinal lymph node metastases are present, a significant number of these patients do have resectable tumors with encouraging long-term survival results. Data are presented to support this view, and steps identified to guide the physicians in selecting the patients who can benefit from this surgical approach.

Thoracic imaging with gallium-67

In the past, gallium-67 imaging has undergone several ups and downs related to its clinical importance. After a period of initial enthusiasm, its role and indications are now established. At present, there are two fields of clinical interest for ⁶⁷Ga-imaging: (1) mediastinal staging in bronchogenic carcinoma and the staging of malignant lymphoma; (2) assessment of activity in interstitial lung diseases, especially sarcoidosis and inflammatory lung disorders. The advantage of ⁶⁷Ga-imaging is that it is highly sensitive for the detection of neoplastic and inflammatory processes, independent of anatomical barriers. Particularly with the challenge of AIDS, ⁶⁷Ga-imaging will gain increasing importance in the future. The low specificity of gallium for detecting underlying disorders precludes its use as a primary diagnostic tool. Therefore, and because of the cost and radiation load, the indications for application will have to be selected very carefully.

The role of mediastinal and multi-organ CT scans in staging presumable surgical candidates with non-small-cell lung cancer

In order to evaluate the role of CT scan and bone scan in staging patients with non-small-cell lung cancer presumably indicated for surgery, 70 consecutive patients who underwent thoracotomy were reviewed. Most of them received mediastinal and multi-organ (brain, liver and adrenal) CT scans and a bone scan. In the most recent 40 of the 70 patients, CT findings of the mediastinal lymph nodes were compared to the pathology following complete sampling. The overall accuracy of the mediastinal CT was 60.0 per cent (12 true positive and 12 true negative), but the negative predictable value was 12/(12 + 3) or 80.0 per cent, whereas 3 were false negatives though they showed an acceptable postoperative course. Sixteen out of 21 patients with one, or at the most, three enlarged nodes detected on CT also did well postoperatively and retrospectively, were considered not to have required mediastinoscopy. A group of patients showing no, or at the most, three enlarged mediastinal lymph nodes on CT may be considered as candidates for surgery even without mediastinoscopy. Multi-organ survey by means of CT was believed cost-ineffective and omittable. Bone scan however, retrospectively detected three true positives among 20 patients with a positive uptake, so that it cannot be omitted out of hand, though further examination of this point is required.

The contribution of anterior mediastinotomy in the diagnosis and evaluation of diseases of the mediastinum and lung

Our experience with 62 consecutive patients who underwent anterior mediastinotomy is presented. A wide range of histological diagnoses was achieved. The highest yield was achieved for mediastinal masses. The overall diagnostic specificity was 64.5% and the diagnostic sensitivity was 98%. However, patient morbidity and mortality were 16.1% and 1.6%, respectively. Therefore, specific guidelines for the procedure are presented.

Comparative studies of computerized tomography and mediastinoscopy for the staging of bronchogenic carcinoma

The accuracy of mediastinal computerized tomographic scans for the staging of bronchogenic carcinoma varies between institutions. In the present study, the sensitivity rate was 57 percent, the specificity rate 69 percent, and the overall accuracy rate 64 percent, all of which were generally lower than rates reported in the recent literature. Different scanning equipment, diagnostic criteria, and patient populations may all contribute to this variance. The data in this report suggest that tumor histologic type and location also influenced the accuracy of computerized tomography. On the basis of this study and review of the literature, it is recommended that any given institution assess the accuracy of its own computerized tomographic mediastinal scans before substituting scanning for mediastinoscopy in the preoperative staging of bronchogenic carcinoma.

Mediastinal assessment for staging and treatment of carcinoma of the lung

Invasive diagnostic procedures for mediastinal assessment, such as mediastinoscopy, are necessitated by the importance of staging lung cancers, both to plan the treatment and to estimate the prognosis. Other noninvasive techniques may complement or be substituted for mediastinoscopy under certain specific clinical settings. Thus with the introduction of newer diagnostic technologies, such as computed axial tomography, the strategy for mediastinal assessment should be continually reevaluated. In this review, the diagnostic sensitivity, specificity, and overall accuracy of various techniques reported in the literature are examined to elucidate their current roles in assessing the mediastinal involvement in patients with lung cancer.

Role of mediastinoscopy in pretreatment staging of patients with primary lung cancer

Since the introduction of mediastinoscopy, there has been a great deal of discussion regarding indications for this technique and the significance of positive findings. We undertook this study to determine the role of clinical staging and the value of routine mediastinoscopy in the treatment selection of patients with primary lung cancer. From 1975 to 1983, 1,259 consecutive patients with proven and operable lung cancer underwent preresection mediastinoscopy. Nodes were sampled at three levels, and findings were recorded by location, invasiveness, and histology. There were no operative deaths, but 3 patients had a major complication. Mediastinoscopy was positive in 339 (27%) patients and negative in 920 (73%). In the group with positive findings, 303 patients had no operation because a curative resection was not possible (extranodal metastases, 180; location, 76; histology, 47). No patient survived 5 years, and only 4% survived 2 years. Of the 36 patients considered to have operable disease, 28 underwent resection with a projected 5-year survival of 18%. In the group with negative findings, 89% had a curative resection with a hospital mortality of 3.2% and 5-year survival of 53%. When results of mediastinoscopy were correlated with findings at thoracotomy, the sensitivity of the test was 93% on nodes in the superior mediastinum and the specificity, 100%. This study shows that mediastinoscopy is safe and is an accurate indicator of the presence or absence of tumor in superior mediastinal nodes. If positive nodes are found, a curative resection is generally not possible, thoracotomy is avoided, and the overall survival is low.