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Ninety-two patients with histologically confirmed bronchogenic carcinoma treated by surgical resection of the tumour were subsequently given immunotherapy with BCG (Glaxo). The patients were randomly allocated into three groups. Twenty-nine patients received multipuncture BCG (50 to

ABSTRACr Gallium 67 citrate was evaluated with conventional scanning and emission computed tomography (CT) scanning as a method of pretreatment staging of the intrathoracic, especially mediastinal, spread of lung cancer. Of 31 patients with tumours of various histological types, the isotope was concentrated in the primary lesion in all but one. In 10 out of 12 patients who underwent surgical exploration conventional gallium scanning correctly indicated the mediastinum to be clear and identified two other patients with a tumour of the mediastinum not recognised by chest radiography or emission CT gallium scanning. Neither conventional nor emission CT gallium scanning produced false positive images. Conventional gallium scanning can give information about the mediastinum not available from chest radiographs or bronchoscopy.Since the introduction of gallium 67 citrate into clinical medicine by Edwards and Hays in 1969' there have been several studies of its use in lung cancer. These have shown a sensitivity for detecting the primary lesion of 50-100%, as well as variation in its accuracy in assessing the mediastinum.2-6 Most of the studies were performed with a rectilinear scanner. Since the introduction of improved imaging equipment, including the gamma camera, and facilities for performing emission computed tomography (CT) there have been only a few studies examining the effect of these advances on the accuracy of gallium imaging in lung cancer.7Our aim was to see whether the improvements could increase the sensitivity of gallium 67 imaging for the primary lesion, and also increase its sensitivity and specificity in the detection of mediastinal node tumours. MethodsThirty one consecutive patients were assessed in a coded prospective study. After bronchoscopy each patient was given 160 MBq of gallium 67 citrate and had conventional (Ga-C) and emission CT images recorded of the thorax 72 hours after injection. Imaging was performed with a large field of view gamma camera (IGE 400T) that had a medium energy collimator and a triple peak energy window. For the emission CT sequence a series of 64 views was obtained at equiangular intervals with an acquisition time of 20 seconds per view. Transverse sections through the thorax were reconstructed from this series of projection images.The conventional gallium images, emission CT data, and chest radiographs were assessed separately by a clinician (RCFL) and a physicist (CJG). For the interpretation of the emission CT data two techniques were used. The original series of 64 views was displayed as a rapid movie, giving the appearance of the patient rotating in front of the camera, with good depth perception from the motion parallax effect.8The reconstructed transverse sections were also viewed in the conventional manner. Representative views from an emission CT sequence are shown in figure 1. The reconstructed transverse views were also viewed in the conventional manner. Figure 2 96 on 7 May 2018 by guest. Protected by copyright.