Wenli Cai PhD, Presenter: Nothing to Disclose

Malek Tabbara MD, Abstract Co-Author: Nothing to Disclose

Gordon J. Harris PhD, Abstract Co-Author: Medical Advisory Board, Fovia, Inc

Marc de Moya MD, Abstract Co-Author: Nothing to Disclose

Volumetric measurement is the essential step for quantifying pneumothorax in CT images and thus guides the emergency treatment of trauma patients. The purpose of this study was to develop and evaluate an automated computer-aided volumetry (CAV) scheme for pneumothorax using the dynamic-thresholding level-set method.

Two pigs and sixteen trauma patient cases were selected for the assessment of the accuracy of the automated CAV scheme for pneumothorax. The volume of the bilateral pneumothoraces in pigs was dictated by 25cc increments of air manually injected up to 600cc. A scan was performed after each incremental injection. Our CAV of pneumothorax consists of three automated steps: (1) The left and right lungs were segmented using region-growing and morphological operators; (2) The pneumothoraces were detected based on CT values and minimum volume size; (3) Finally, the dynamic-thresholding level set was initialized to the above seed regions, and they were evolved to delineate the boundary of the individual pneumothorax. The resulting boundaries were used for calculation of the volume of the pneumothoraces. The volume of pneumothorax calculated by our automated CAV scheme was subjected to animal and patient validation study. The reference standards were the injected air volume for the animal study and a clinical score of pneumothorax for the patient study, respectively.

Our automated CAV scheme yielded a mean difference of 0.73±2.23cc compared to the 25cc air volume manually injected in each scan. Two groups of volumetric measurement in the animal study were strongly correlated (correlation coefficient = 0.999). In the patient study the correlation coefficient between clinical score and volumetric measurement was 0.897.

Our automated CAV scheme for pneumothorax can provide an accurate and efficient volumetric measurement. The correlation coefficient in patient validation study demonstrated that the results were highly correlated to the clinical scoring system.

Our automated volumetry can provide accurate volumes of pneumothorax that is essential information for managing emergency trauma patients and assisting the surgeon’s decision-making.

Cai, W, Tabbara, M, Harris, G, de Moya, M, Automated Volumetric Measurement of Pneumothorax in CT Images for Trauma Patients.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009323.html