Indeterminate mediastinal invasion in bronchogenic carcinoma: CT evaluation

The computed tomographic (CT) scans of 80 patients with bronchogenic carcinoma classified as indeterminate for direct mediastinal invasion were retrospectively reviewed after the patients had undergone thoracotomy. Forty-eight (60%) of the masses were resectable, without invasion of the mediastinum, 18 (22%) focally invaded the mediastinum but were technically resectable, and 14 (18%) invaded the mediastinum and were not technically resectable. Although in most circumstances in this relatively small subset of patients CT was not helpful in differentiating masses with and without mediastinal invasion, CT was able to separate a large group of masses that were likely to be technically resectable. Thirty-six (97%) of 37 masses with one or more of these CT findings were considered technically resectable: contact of 3 cm or less with mediastinum, less than 90 degrees of contact with aorta, and mediastinal fat between mass and mediastinal structures. Of these 36 masses, 28 were resectable without mediastinal invasion, and eight were resectable with focal limited mediastinal invasion.     

Small-cell lung carcinoma: CT imaging features

Small cell lung carcinoma (SCLC) typically is central in location. It is a very aggressive tumor characterized by its propensity for invasion of mediastinal structures, frequently, the ipsilateral pulmonary artery, multifocal nodal metastases and high frequency of distant metastases at initial presentation. CT is very sensitive and effective for local and regional staging. Combined with other diagnostic modalities, especially PET imaging, it allows whole body imaging for accurate staging, which is mandatory for therapeutic management. The different CT imaging features of SCLC and its more specific imaging characteristics will be reviewed in this article.     

Pleural and chest wall invasion in bronchogenic carcinoma: CT evaluation

CT scans of 47 patients who had peripheral bronchogenic carcinoma contiguous to the pleural surface and who had undergone thoracotomy were retrospectively reviewed. The CT features of the primary neoplasm that were analyzed included the angle and amount of contact with the adjacent pleural surface, associated pleural thickening, fat plane between the tumor and chest wall, rib destruction, and chest wall mass. CT was of limited predictive value in separating those patients who had parietal pleural/chest wall involvement from those who did not. The combination of two or three CT findings (obtuse angle, greater than 3 cm contact with pleural surface, associated pleural thickening) resulted in a sensitivity of 87% and a specificity of 59%. The clinical symptom of focal chest pain, while not as sensitive (67%) as CT, was much more specific (94%) for parietal pleura/chest wall invasion.     

Mediastinal nodes in bronchogenic carcinoma: comparison between CT and mediastinoscopy

Computed tomography (CT) and mediastinoscopy were compared in 151 patients with bronchogenic carcinoma. In all patients in whom findings at mediastinoscopy were negative, all accessible nodes were either removed or sampled at thoracotomy. Several size criteria for identifying nodes as enlarged on CT scans were compared. The long axis greater than or equal to 15 mm and short axis greater than 10 mm had very low sensitivity (61%), and the long axis greater than 5 mm had a low specificity (23%). CT (long axis greater than 10 mm) allowed sensitivity equal to that of mediastinoscopy (79%) in the detection of mediastinal metastases, but the specificity with CT was lower (65% vs. 100%). In seven of 44 patients with nodes greater than 10 mm on CT scans and with positive findings at mediastinoscopy, tumor was present not in the enlarged nodes but rather in normal-sized nodes in a different nodal station. The sensitivity of CT for actual nodal stations involved with tumor was only 66%. Eighty-three percent of patients with false-negative findings at mediastinoscopy but only 33% of patients with false-negative findings at CT had surgically resectable stage IIIa disease.     

T1N0M0 bronchogenic carcinoma: assessment by CT

We reviewed medical records and conventional chest radiographs that showed a solitary T1N0M0 nodule in 23 patients who had non-oat-cell bronchogenic carcinoma. No patient had evidence of metastases, either on the chest radiograph or clinically. All patients underwent computed tomography (CT) examination of the thorax, including the adrenal glands. Only one patient (4%) had mediastinal lymph nodes greater than 1 cm in diameter accessible to mediastinotomy; anterior mediastinotomy confirmed metastatic spread in this patient, which precluded curative resection. Three patients each had a mildly enlarged (2 cm or less) adrenal gland; however, follow-up study suggested that metastasis was not the cause of adrenal enlargement in these patients. This study reinforces concern over whether CT is warranted in the preoperative assessment of T1N0M0 bronchogenic carcinoma.     

Intrathoracic lymph node evaluation by CT and MRI with histopathologic correlation in non-small cell bronchogenic carcinoma

Twenty patients with non-small cell bronchogenic carcinoma were prospectively studied for intrathoracic lymphadenopathy using computed tomography (CT) and magnetic resonance imaging (MRI). The CT and MRI results were correlated with the surgical histopathology results of 103 harvested lymph nodes. Based on node dimension (utilizing a 1-cm cutoff value), neither imaging modality was accurate in predicting the histopathology of the nodes. CT had a sensitivity of 21%, specificity of 95%, and an overall accuracy of 85%; MRI had a sensitivity of 14%, specificity of 97%, and an overall accuracy of 85%. Moreover, CT and MRI detected preoperatively only 17% and 14%, respectively, of the harvested nodes. In summary, lymph node sizes measured by CT and MRI are inaccurate in predicting the benignity or malignancy of lymph nodes. Lymphadenopathy can be present even with a "negative" CT or MRI scan of the thorax.     

Mediastinal lymph node metastases from nonsmall cell bronchogenic carcinoma: reevaluation with CT

We evaluated the sensitivity of CT for detecting mediastinal lymph node metastases in patients with nonsmall cell bronchogenic carcinoma. Computed tomography of 208 cases of surgically proven bronchogenic carcinoma from three institutes was evaluated retrospectively using specific diagnostic criteria. These consisted of two size thresholds for specific mediastinal node regions: 13 mm short transverse diameter for nodes in the subcarinal, precarinal, and tracheobronchial regions and 10 mm for other regions. Based on these criteria, the overall sensitivity of CT was 69%, specificity 94%, and accuracy 86% for detection of metastasis. In cases of adenocarcinoma, sensitivity was 61%, specificity 93%, and accuracy 81%, and in those of squamous cell carcinoma the respective values were 86, 94, and 92%. Comparison between the results using the present criteria with the former criterion of 10 mm short transverse diameter for all mediastinal nodes revealed that the number of false-positive cases decreased markedly. We conclude that more accurate CT evaluation of mediastinal lymph node metastasis in nonsmall cell bronchogenic carcinoma can be achieved with specific size criteria for specific mediastinal regions.     

Mediastinal lymph node metastases from bronchogenic carcinoma: detection with MR imaging and CT

Magnetic resonance (MR) imaging and computed tomography (CT) were compared in a prospective study of 48 patients for the detection of metastatic mediastinal lymphadenopathy from bronchogenic carcinoma. The images were interpreted by three experienced radiologists using a five-point rating scale, enabling receiver operating characteristic (ROC) analysis. Imaging results were evaluated against "truth" data based on analysis of surgical specimens from mediastinoscopy and thoracotomy. All MR images were cardiac gated to reduce cardiac motion artifacts in the mediastinum. MR and CT both performed well, as indicated by similar areas under the ROC curves of 0.779 +/- 0.039 for MR imaging and 0.781 +/- 0.038 for CT scanning. No strong correlation between nodal size and metastatic involvement could be found for either MR or CT results. As long as nodal size remains the sole criterion in the detection of metastatic mediastinal lymphadenopathy, MR imaging is unlikely to enable better interpretations than CT scanning.     

Biliary carcinoma: CT evaluation of extrahepatic spread

The authors studied the computed tomographic (CT) images obtained in 56 patients with pathologically proved biliary cancer and 75 patients with no evidence of biliary disease, attempting to define the normal anatomy of the lymphatic system draining the bile ducts and the prevalence of extrahepatic spread of primary biliary cancer into these retroperitoneal planes. Of 20 patients with gallbladder cancer, 14 (70%) had proved adenopathy and nine (45%) had peritoneal spread at presentation, and another three later developed carcinomatosis. Of 22 patients with proximal cholangiocarcinoma, 16 (73%) had nodal involvement at presentation, four later developed adenopathy, and five had peritoneal dissemination. Distal or diffuse cholangiocarcinomas were less associated with metastatic nodes or peritoneal spread. For all biliary cancers, the nodes most commonly involved were the node of the foramen of Winslow, the superior pancreatoduodenal node, and the posterior pancreatoduodenal chain. Extrahepatic tumor spread produced proximal intestinal obstruction in 13 patients (23%). CT reliably demonstrates lymphatic or other extrahepatic spread of biliary cancers, which may have an important bearing on management decisions.     

Computed tomographic evaluation of adrenal glands in patients with bronchogenic carcinoma

One hundred thirty-four patients with histo-pathologically proven bronchogenic carcinoma underwent computed tomography (CT) of the thorax and adrenal glands. Prospectively, 23 of the 134 patients had adrenal metastasis, based on CT criteria for enlargement of the gland. Retrospectively, however, some proved to be false positives. In addition, the diagnosis of adrenal metastasis frequently altered the initial staging and the treatment modality. We suggest that valid diagnoses of adrenal metastases on CT scan be made on the basis of altered shape as well as on altered size of the gland.