[Spiral computed tomography in the diagnosis and staging of bronchopulmonary carcinoma]

Spiral or helical technology is a new computed tomographic technique based on the continuous acquisition of volumetric CT data during continuous x-ray beam rotation and continuous patient transportation at constant velocity. It has many advantages over conventional CT: the authors briefly review the basic principles of spiral CT and discuss the applications and the possible advantages in the assessment of lung cancer. The most important characteristics of spiral CT are rapid image acquisition, allowing a single-breath-hold scan of the lung, and the ability to obtain axial image reconstructions at arbitrary and overlapping intervals, thus allowing the detection of small lesions that otherwise would be inconspicuous because of respiratory misregistration or partial volume averaging. This leads to better identification of small pulmonary nodules and to high quality multiplanar reconstructions that can be useful in the study of mediastinal lymph nodes and the vascular and tracheobronchial spreading of lung cancer. Many of the spiral CT scanners allow for 40 sec extended spiral acquisition during a single-breath-hold, permitting the evaluation of the thorax and the upper abdomen. This usually includes the adrenals and the whole liver, thus allowing a rapid staging of thoracic neoplasms, with an accuracy higher than that of conventional CT.