[Evaluation of multi-slice spiral ct scan and image reconstruction technology in estimating costal cartilage volume]

To investigate the accuracy of multi-slice spiral CT (MSCT) scan and image reconstruction technology for measuring morphological parameters of costal cartilages and to evaluate the volume of costal cartilages.

Between March and August 2013, 75 patients with congenital microtia and scheduled for auricle reconstruction were included in the study. Of 75 patients, there were 49 males and 26 females with a mean age of 8 years and 5 months (range, 5 years and 7 months to 32 years and 7 months) and a mean weight of 29.5 kg (range, 21-82 kg). A Philips Brilliance 64 MSCT machine was used to scan 1st-12th costal cartilages with the parameters based on the age and weight of the patients. All the data were transported to the workstation for reconstructing the image of the costal cartilages with the technique of maximum intensity projection (MIP) and volume rendering technique (VRT). Then the morphologies of costal cartilages were observed through the images on VRT; the width of the costal cartilaginous ends close to ribs (W) and the length of thetotal cartilage (L) were measured and compared with their counterparts (W' and L') after the costal cartilages were harvested during the processes of auricle reconstructions to analyze consistency between these two sets of data.

The morphologies of ribs and costal cartilages shown on VRT image got fine sharpness, verisimilitude, and stereoscopic impressions. A total of 192 costal cartilages were examined. The results showed that the widths of the costal cartilaginous ends close to ribs (W) was (9.69 ± 1.67) mm, and W' was (9.73 ± 1.64) mm, showing no significant difference between W and W' (t = -1.800, P = 0.073), and interclass correlation coefficient (ICC) test showed Cronbach's α = 0.993. The length of the total cartilage (L) was (83.03 ± 23.86) mm, and L' was (81.83 ± 16.43) mm, showing no significant difference between L and L' (t = -1.367, P = 0.173), and ICC test showed Cronbach's α = 0.904. Linear-regression analysis showed L = 1.28 x L' - 21.93 (R2 = 0.780, F = 673.427, P = 0.000). The results suggested there was a good consistency between these two sets of data.

Scanning costal cartilages with appropriate parameters and reconstructing the cartilaginous image with MIP is an effective method to measure the width and length of costal cartilage and to estimate costal cartilage volume, which can provide accurate reference for plastic surgery together with reading the morphology from the image on VRT.