SPIRAL VERSUS CONVENTIONAL CT IN SOFT-TISSUE DIAGNOSIS

Spiral volumetric computed tomography (SVCT) has been predicted to improve vascular and organ enhancement with little effect on image quality. To see if this was the case, we studied 100 patients referred for computed tomography where we would normally have performed dynamic incremental computed tomography (DICT). Patients were randomly allocated to undergo either standard DICT or SVCT. The resulting images were analysed for overall quality, the degree of contrast medium enhancement and the extent of artefacts associated with the technique. No statistically significant difference in overall image quality between SVCT and DICT was found, apart from images of the hepatic parenchyma where the quality was significantly worse on SVCT (P<0.05) due to the low mA permissible. Contrast enhancement was better with SVCT, although only for the thorax (P<0.01) and the group taken as a whole (P<0.01) did this improvement reach statistical significance. There was no statistically significant difference between the extent of artefacts observed in the two techniques. As expected, all acquisition times were shorter using SVCT. The benefits of SVCT have been well described and include the absolute contiguity of the reconstructed images and the ability to obtain many images at peak contrast enhancement. We have confirmed the latter effect. We are now also satisfied that there is no appreciable loss of overall image quality except where large volumes of solid tissue are being examined (e.g. liver).