Evaluation of the mediastinum by gallium-67 scintigraphy in lung cancer

Radiometals in Imaging and Therapy: Highlighting Two Decades of Research

The present article highlights the important progress made in the last two decades in the fields of molecular imaging and radionuclide therapy. Advancements in radiometal-based positron emission tomography, single photon emission computerized tomography, and radionuclide therapy are illustrated in terms of their production routes and ease of radiolabeling. Applications in clinical diagnostic and radionuclide therapy are considered, including human studies under clinical trials; their current stages of clinical translations and findings are summarized. Because the metalloid astatine is used for imaging and radionuclide therapy, it is included in this review. In regard to radionuclide therapy, both beta-minus (β-) and alpha (α)-emitting radionuclides are discussed by highlighting their production routes, targeted radiopharmaceuticals, and current clinical translation stage.

Yield of Total Body GA-67 Scintigraphy in the Staging of Non-Small Cell Lung Cancer

One hundred and one patients with histologically proved non-small cell lung cancer underwent whole body gallium-67 (TB Ga-67) scintigraphy as a part of their routine pretreatment evaluation. Twenty-eight of these patients were subsequently operated and pathologically staged for hilar and mediastinal disease. Two other patients underwent mediastinoscopy, but were judged unresectable at that time. All had computed tomography (CT) of the thorax, as well as radionuclide or CT scans of suspicious metastatic areas, and were carefully followed-up. When possible, a biopsy was performed of each suspected metastasis. Primary lung tumors concentrated Ga-67 in 94 patients. Sensitivity, specificity, and accuracy for hilar and mediastinal node metastases were 58%, 89%, and 77%, respectively. There were no false-negative gallium scans as regards secondary involvement of both liver and bone, whereas only 1 of the 4 brain metastases was detected by the technique. Sensitivity, specificity, and accuracy for all metastatic sites were 82%, 38%, and 56%, respectively. Fifty-five patients were classified as having a more advanced stage of disease by TB Ga-67 scintigraphy than at the initial clinical evaluation. However, 42 gallium-staged patients were ultimately re-classified differently according to all available clinical data. Using TB Ga-67 scintigraphy, 21 patients were found to have occult metastases which would not otherwise have been recognized; for the above reason, an unnecessary intervention was avoided in 6 of them.

Efficacy of computed tomography of the thorax and upper abdomen and whole-body gallium scintigraphy for staging of lung cancer

To assess the efficacy of performing both computed tomography (CT) of the thorax and upper abdomen and whole-body gallium scintigraphy for staging lung cancer, the results of each test were compared with those obtained by chest radiography and clinical examination in 100 patients. Clinical efficacy was defined in terms of accuracy in staging the tumor based either on surgery, biopsy, or clinical and radiologic follow-up. The CT provided significantly superior accuracy in 27 patients and minor additional staging information in 17 patients compared with the gallium scan. Whole-body gallium scintigraphy provided important additional information in nine patients and minor additional information in a further eight. The diagnostic yield of CT and gallium scanning was considered equivalent in 39 cases. Of the nine cases in which gallium was significantly superior to CT, clinical findings which suggested the presence of metastases had been noted before the scan in four cases. The authors' results confirm the utility of CT for staging lung cancer and indicate that the additional yield from gallium scintigraphy is relatively low provided a thorough history and physical examination have been performed.

The prognostic significance of preoperative assessment of mediastinal lymph nodes in patients with lung cancer

In order to evaluate the prognostic significance of the preoperative assessment of mediastinal lymph nodes, 100 patients with potentially operable lung cancer underwent two-plane tomography, computed tomography (CT), transbronchial needle aspiration (TBNA; 47 patients), and cervical mediastinoscopy. Mediastinoscopy proved to be the most accurate staging procedure. Tomography was less specific, detecting only advanced mediastinal node involvement, and CT was as sensitive as mediastinoscopy but sensibly less specific. TBNA gave no false positive results but a false negative rate of 25.5 percent. Accurate preoperative staging of mediastinal nodes is mandatory to optimize the resectability rate of lung cancer. Where metastatic involvement of mediastinal nodes was preoperatively documented at more than one level, tumors were invariably unresectable. Mediastinoscopic demonstration of intracapsular metastases at only one level did not preclude complete resection. Before thoracotomy, confirmation of neoplastic spread to mediastinal nodes suggests very low survival rates, especially in patients with incomplete removal of tumors.

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 nuclear medicine in pulmonary neoplastic processes

It has been demonstrated that the single most important factor in determining survival in patients with bronchogenic carcinoma is the extent of spread of metastasis from the primary lesion. This explains the extensive efforts in developing accurate staging tests for pulmonary tumors, both primary and metastatic, with special emphasis on the determination of pulmonary hilar and mediastinal spread of disease. Continued improvements in nuclear medicine instrumentation along with the development of tumor specific radiopharmaceuticals, as well as agents that have the capability of tracking tumor viability, have changed the orientation of scintigraphic techniques in the evaluation of pulmonary neoplastic processes. Gallium scintigraphy is no longer considered as a primary imaging modality in the staging of pulmonary tumors, and in most institutions has been replaced by computed tomography (CT) for this purpose. It has been demonstrated that gallium, relative to other imaging modalities, is a sensitive indicator of hilar spread of tumor. However, because of the normally high background activity within the sternum and spine, mediastinal abnormalities are poorly detected. Since most pulmonary tumors metastasize via regional nodes to the pulmonary hilum and then to the mediastinum, the high sensitivity for the detection of pulmonary hilar abnormalities and the high specificity for mediastinal lesion detection suggest that gallium scintigraphy is a valuable adjunctive test when used appropriately. Thallium 201 as a tumor agent is being studied by several institutions. Preliminary results indicate a high degree of sensitivity for the detection of pulmonary hilar and mediastinal lesions and there are early indications that thallium is a promising agent to evaluate tumor viability. With the development of new generation monoclonal antibodies, the prospects for highly sensitive and specific agents for detecting hilar and mediastinal spread of tumor is extremely encouraging. CT and NMR have made major contributions to the noninvasive workup of patients with bronchogenic carcinoma. Neither modality has been demonstrated to be accurate enough to adequately evaluate this patient population. Thus, there is a critical need for new noninvasive tests that will accurately assess the status of the patient so that appropriate therapy can be instituted.

Gallium scanning and tomography in the preoperative evaluation of lung cancer

Discrepant reports on the utility of gallium scanning in the preoperative evaluation of patients with lung cancer prompted a prospective study of the test. The authors studied 47 patients with lung cancer who underwent preoperative gallium scanning and frontal tomography of the mediastinum. Both tests were found to be most accurate in predicting the presence of mediastinal metastases among patients with squamous cell carcinoma. Both test may help direct surgical planning in patients with known squamous cell carcinoma of the lung.

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.

Radiologic evaluation of the mediastinum

New imaging techniques have had a major impact on radiologic evaluation of the mediastinum. Computed tomography has led the way in defining internal anatomy noninvasively. Ultrasound plays a small but well-defined role in the evaluation of certain mediastinal masses. Digital vascular imaging has, in certain instances, replaced conventional angiography, though it seems unlikely to render conventional angiography obsolete. Other modalities such as magnetic resonance imaging are being applied and promise to become even more important in the near future. Finally, mediastinal sampling by needle biopsy under radiologic guidance has been shown to be a reliable technique when appropriately utilized.

The value of computed tomography in staging bronchogenic carcinoma: a changing role for mediastinoscopy

Forty-one patients underwent operative staging for bronchogenic carcinoma following computed tomography of the mediastinum between August, 1982, and March, 1984. Twenty-seven patients were classified as Stage I preoperatively; in 2 of them, positive mediastinal nodes were found at thoracotomy. For the 14 patients in whom positive nodes had been identified by computed tomographic (CT) scanning, staging was unchanged as a result of the findings at mediastinoscopy or thoracotomy or both. In this series, computed tomography had a sensitivity of 89%, a specificity of 100%, and an overall accuracy rate of 95%. We conclude that mediastinoscopy is not needed in patients without evidence of mediastinal nodal enlargement by CT scan; when performed, it should be guided toward those nodes identified as positive.

Critical evaluation of the gallium-67 scan for surgical patients with lung cancer

Seventy-five patients with lung cancer underwent a gallium scan and thoracotomy with total mediastinal nodal dissection. Evaluation of mediastinal lymph nodes by means of the gallium scan showed a sensitivity of 23 percent (3/13), a specificity of 82 percent (31/38), an accuracy of 67 percent (34/51), a positive predictive valve of 30 percent (3/10), and a negative predictive value of 76 percent (31/41) in those patients whose primary tumors demonstrated uptake of radioactive gallium. The low sensitivity was due to an inability to detect microscopic disease in mediastinal lymph nodes. The specificity was decreased by gallium-67 uptake in enlarged inflamed nodes that contained no metastases. These results do not support the use of the gallium scan in the selection of patients with lung cancer for thoracotomy.

Accuracy of chest computerized tomography in detecting malignant hilar and mediastinal involvement by squamous cell carcinoma of the lung

The accuracy of chest computerized tomography (CT) in detecting malignant hilar and mediastinal involvement by squamous cell carcinoma of the lung is examined. The preoperative chest CT scans of 74 patients with pathologically proven squamous cell lung carcinoma were prospectively and retrospectively reviewed. Criteria for the diagnosis of malignant hilar involvement were nonvascular mass enlarging the hilum; local alteration of hilar contour; adenopathy greater than 1 cm; thickened posterior wall of the bronchus intermedius and distal upper lobe bronchi; and bronchial displacement, compression, and obstruction. Criteria for the diagnosis of malignant mediastinal involvement were confluence of tumor with the mediastinum, altered contour of the azygoesophageal recess, thickened posterior wall of the proximal main stem bronchi, and mediastinal adenopathy greater than 1 cm. Calcified hilar and mediastinal nodes were considered benign. Our results, corrected for reader error, were 92% sensitive, 92% specific, and 96% accurate in the hilum and 95% sensitive, 77% specific, and 82% accurate in the mediastinum. These data support a significant role for chest CT in the preoperative staging of non small cell lung carcinoma.

Sensitivity of chest radiography, computed tomography, and gallium scanning to metastasis of lung carcinoma

To determine the efficacy of radiologic techniques in preoperative staging of the mediastinum for lung carcinoma, the authors studied 45 patients with chest films supplemented with oblique views, esophagrams, gallium scans, and computed tomograms (CT). They interpreted the studies and correlated surgical findings using a modified classification of lymph node regions. The mediastinum was positive on chest films in 14 of the 21 cases with pathologically proved mediastinal metastases (33% false-negative). Gallium scans in cases with a positive primary were positive in 12 of 15 cases with mediastinal or hilar metastases (20% false-negative). Computed tomography showed nodes over 1 or 1.5 cm in size in or adjacent to the biopsy-positive node region in 18 of 19 patients (5% false-negative), extranodal mediastinal involvement, and 9 of 10 proven hilar metastases. Computed tomography is a sensitive screening technique in patients who would otherwise require an invasive staging procedure, but is not highly specific (false-positive rate 38%).

The role of gallium-67 in the clinical evaluation of cancer

This review is based primarily on historic data, and it examines the indications for and limitations of gallium-67 scanning in the evaluation of patients with neoplasms. The use of gallium-67 scans is discussed according to tumor type, and data from the most representative and comprehensive studies are included. The results described, some of which were obtained primarily with older imaging techniques, should be regarded as representing the minimum that can be expected from application of this imaging procedure.

Evaluation of tomography and mediastinoscopy for the detection of mediastinal lymph node metastases

In a prospective study of 88 patients seen consecutively with proven or suspected bronchial carcinoma, the validity of x-ray tomography and routine mediastinoscopy was tested for the detection and evaluation of mediastinal lymph node metastases. Positive mediastinum was defined as malignant tissue found in the mediastinum and negative mediastinum as mediastinoscopy with negative results plus a negative intraoperative mediastinal lymph node dissection. Thirty-four patients were eliminated from the analysis because carcinoma was not found or because mediastinal evaluation was incomplete by these criteria. Twenty-eight of the remaining 54 patients had mediastinal metastases. Sensitivity was 67% for tomography and 79% for mediastinoscopy. Specificity was 92% for tomography and 100% for mediastinoscopy. The differences were not significant. Sixty-six of 85 mediastinoscopies were unnecessary or unhelpful in the decision to exclude a patient from surgical intervention. Among 19 patients with lesions presumed to be inoperable based on results of mediastinoscopy (i.e., perinodal metastatic growth suspected by palpation or histologically proven), 14 patients had positive tomographic scans and 1 could not be evaluated radiographically because of right upper lobe atelectasis. We conclude that tomography of the upper mediastinum should be used to select patients for mediastinoscopy.

Pre-operative mediastinal evaluation in primary bronchial carcinoma--a review of staging investigations

A review of staging investigations in the preoperative evaluation of mediastinal involvement in primary bronchial carcinoma is presented. The following conclusions are offered as guidelines for the use of mediastinal staging procedures in clinical practice: Surgical staging methods have the over-riding advantage of superior specificity over indirect imaging techniques. Where 67Ga-imaging or CT scanning are not available, routine pre-operative mediastinoscopy or, when appropriate, mediastinotomy will identify most patients with non-resectable disease but this approach entails a high proportion of true negative examinations. Radioisotope ventilation and perfusion lung imaging has no place in the pre-operative staging of lung cancer. Where the techniques are available, 67Ga-imaging and CT scanning have a use in selecting patients for mediastinal exploration. A negative mediastinal 67Ga scan or a negative CT examination suggest that mediastinal exploration will be unrewarding in the vast majority of cases and may be omitted prior to thoracotomy. A positive mediastinal 67Ga scan or the demonstration of abnormal mediastinal nodes by CT is an indication for mediastinal exploration which, if negative should be followed by thoracotomy.

Thoracic neoplasms: imaging requirements for diagnosis and staging

This article reviews the pathophysiology of thoracic neoplasms and discusses current imaging recommendations for diagnosis and staging of these tumors. Particular emphasis is given to primary lung cancers, which comprise a variety of tumors of differing histologic type and behavior. The development of cost-effective diagnostic/staging sequences with continually changing imaging technology continues to be a challenging goal. Our recommendations are based on the TNM system and data from the current literature employing the experience from our institution.

Computed tomography in lung cancer

Computed-assisted tomography produces a cross-sectional image of the body using x-ray absorption measurements. Density differences are much more apparent than on conventional radiographs, although spatial resolution is not so fine. Lung cancer, can be evaluated accurately with regard to size, location, and whether regional or mediastinal lymph nodes are enlarged. Although enlarged granulomatous nodes generally tend to be dense, histologic specificity is not available. Computed tomography is recommended as a screening technique in lung cancer staging for patients whose routine radiographs are normal but whose primary lesions fulfill criteria for mediastinoscopy. If findings on computed tomography are normal, thoracotomy should then be performed; if enlarged nodes are detected, then a biopsy is needed to exclude operability. This strategy presumes that computed tomography has high sensitivity, although it remains to be proven by further experience whether the false-negative rate of computed tomography is an acceptable 10 to 15 percent. Computed tomography has been shown to be of considerable value in optimizing radiation therapy of lung cancer, and in diagnosing pleural complications of the cancer or its treatment.

Role of gallium 67 thoracic scintigraphy in the diagnosis and staging of patients suspected of bronchial carcinoma

Gallium 67 (67Ga) lung scanning was performed in 100 consecutive cases in which because of the history, clinical data, or abnormal radiological findings, a bronchial carcinoma was suspected. This study allows the conclusion that a negative as well as a positive scan is an important element in the diagnosis of some cases of bronchial carcinoma. The method is most helpful in the preoperative diagnosis of circumscribed peripheral shadows and in the assessment of suspected hilar enlargement; it may even visualise hidden malignant tumours. Gallium 67 scanning is also valuable in the assessment of hilar and mediastinal involvement in the presence of a proven primary lung tumour. This study supports the view that in the presence of a negative mediastinal scan the patient may be spared mediastinoscopy and be referred directly for operation.

Sequential scintigraphic staging of small cell carcinoma

Thirty patients with small cell carcinoma (SCC) of the lung were sequentially staged following a history and physical exam with liver, bran, bone, and gallium-67 citrate scans. Scintigraphic evaluation disclosed 7 of 30 patients (23%) with advanced disease, stage IIIM1. When Gallium-67 scans were used as the sole criteria for staging, they proved to be accurate and identified six of the seven patients with occult metastatic disease. Gallium-67 scans proved to be accurate in detecting thoracic and extrathoracic metastases in the 30 patients with SCC, especially within the liver and lymph node-bearing area. The diagnostic accuracy of gallium-67 fell in regions such as bone or brain. Despite the limitations of gallium-67 scanning, the authors conclude that these scans are useful in staging patients with SCC and should be the initial scans used in staging such patients.

Current aspects of nuclear imaging in clinical oncology

This presentation will focus on the recent developments in nuclear medicine that relate to diagnosis and staging in the cancer patient. The commercial availability of new Agar cameras as well as longitudinal tomographic scanning devices has improved gallium imaging significantly. This has enhanced tumor detection and resulted in better use of gallium scanning in the cancer patient. Areas of controversy have also developed. In particular, the question of whether or not the gallium scan can be used to avoid mediastinoscopy in some case of bronchogenic carcinoma will be detailed. Techniques in nuclear medicine must be carefully integrated with other noninvasive investigation such as CT and ultrasound. At Yale, the authors have gathered considerable data indicating the best way to interact nuclear medicine radionuclide scintigraphy of the liver with the ultrasound examination. Our approach to this problem for the detection of focal disease in the liver will be discussed. 99mTc-HIDA has been proven useful in a wide variety of biliary disorders. Use of scintigraphy in the evaluation of cholangio-enteric bypass procedures in the cancer patient will be reviewed.

Noninvasive evaluation of mediastinal metastases in bronchogenic carcinoma: a prospective comparison of chest radiography and gallium-67 scanning

Evaluation of regional node involvement in patients with bronchogenic carcinoma is a crucial step in determining therapy and prognosis. Mediastinoscopy has been recommended for staging all potentially operable cases, but technical limitations and the need for anesthesia make this impractical. Gallium-67 scanning and chest radiography were prospectively compared as noninvasive means of evaluating spread to regional nodes in 75 patients with bronchogenic carcinoma in whom histologic evaluation of hilar and mediastinal nodes was performed. Gallium scanning was more accurate than chest radiography in assessing regional nodes (overall accuracy 85.3% vs. 56%, P less than 0.05). When positive, both procedures correctly indicate malignant involvement of regional nodes (85% vs. 87.3%). A negative gallium scan, however, was significantly more accurate in predicting the absence of such involvement (80% vs. 40%, P less than 0.01). Gallium scanning appears to be a reliable, noninvasive means of assessing mediastinal spread of bronchogenic carcinoma and when used in conjunction with radiographic findings, allows selection of appropriate patients for surgical staging procedures.

Diagnostic work-up of chest disease

The most important aids available to the thoracic surgeon for the evaluation of pulmonary disease are history, physical examination, and chest x-ray. Proper use of these modalities will allow a diagnosis to be made quickly with a minimum of hardship and risk to the patient and hence permit a reasonable and logical approach to therapy to be instituted. In addition, the various ancillary tests that are occasionally indicated in the work-up of patients with pulmonary disease have been reviewed, and the indications for each have been outlined.

Gallium-67 citrate imaging studies of the lung

In spite of localization of gallium in the lungs in a large variety of inflammatory pulmonary diseases, the chest radiograph is and will continue to be the principal diagnostic tool for evaluation of pulmonary inflammatory disease. The 67Ga-citrate scan, however, serves as a study complementary to chest radiography because it indicates the extent, localization, and degree of activity of the inflammatory disease with greater accuracy than do the radiographic studies. It also permits the physician to follow progression of the disease or response to treatment and possible to detect disseminated interstitial disease not visualized on radiographs. Gallium-67 scanning may be used in the evaluation of patients with lymphorecticular neoplasms (Hodgkin's disease and malignant lymphomas) both during initial staging and in evaluation of the response to therapy. The 67Ga-citrate scan is useful in the evaluation of patients with lung cancer provided its limitations are kept in mind. It cannot and should not replace the pathologist's microscope. The scan is useful as a screening test only in patients who have radiographic lesions not consistent with inflammatory disease and in whom invasive diagnostic procedures or exploratory surgery are contraindicated unless the probability of detecting a resectable tumor is high. However, the limited resolution of the scanning system restricts the possibility of detecting lesions before they become radiographically visible. The histologic type of the lesion appears to have no effect on the probability of detection. As a noninvasive procedure, the 67Ga-citrate scan complements mediastinoscopy by indicating which lymph nodes should be biopsied. It is also useful in evaluation of the controlateral hilar node region. The scan frequently detects clinically unsuspected extrathoracic lesions. It may therefore be a useful initial procedure in guiding the work-up of the patient with a known or strongly suspected tumor. The combination of the 67Ga scan with the chest radiograph could provide the information necessary for presurgical clinical staging in patients who have no symptoms that suggest distant metastases. Gallium-67 scans may be useful in indicating the effectiveness of treatment and the sensitivity of a tumor to radiation.