[Spiral volumetric scanning and its applications in thoracic pathology]

Spiral scanning (BSV) is a newly acquired scanning technique for all or part of the thoracic volume in a single breath-hold. It offers many advantages when compared to conventional CT scanning. The study of the lungs with a single breath-hold avoids the inconvenience of an anatomical discontinuity while acquiring the information. In a population of patients presenting with multiple, or solitary pulmonary nodules, or the absence of nodule, BSV shows 30 to 40% of supplementary nodules when compared to conventional scanning techniques. BSV enables the optimal use of contrast products in which the iodine is poorly concentrated to study the pulmonary vessels. Certainly this technique will not replace pulmonary angiography for the diagnosis of pulmonary emboli. However, it may be used first in certain situations, dispensing with invasive angiography in patients with an increased risk, or in the initial assessment of patients with pulmonary arterial hypertension of unknown aetiology, or to follow a previously documented pulmonary emboli. The correlation between spiral scanning and conventional angiography for the diagnosis of pulmonary emboli is excellent, to the level of segmental arteries. Finally the continuity, both anatomically and for the lesions obtained by BSV is such that it is now possible to apply to thoracic pathology techniques of multiplanar and three dimensional reconstruction. If all the information is contained in conventional transversal imaging slice by slice, not everything is perceived by the observer because the information is inconveniently presented because the anatomical and lesional picture is deconstructed. The reconstruction of the volume inspected in coronal, sagittal, oblique or three-dimensional viewing, furnishes supplementary information and announces the arrival of trachea-bronchography, and non-invasive angiography three-dimensionally. In parallel to the expected progress in IRM angiography, three-dimensional angio-CT of the thoracic vessels after appropriate evaluation is going to be substituted for more invasive techniques which are currently used.