LOW-DOSE SPIRAL COMPUTED-TOMOGRAPHY FOR MEASURING ABDOMINAL FAT VOLUME AND DISTRIBUTION IN A CLINICAL SETTING

Objectives: Computed tomography (CT) has been used to measure body com position, however, a technique with reduced radiation exposure has not yet been introduced. This study tested a low-dose spiral CT technique on a phantom to determine its validity and reproducibility. The metho d was then applied for volume and distribution measurements in patient s. Design: Construction and measurement of a phantom followed by measu rement of patients referred to CT for clinical indications. Setting: R adiology Department, University Hospital. Subjects: Twenty-four post-g astrectomy patients. Intervention: A 22 cm phantom with a known amount of water and fat was scanned using high- and low-dose technique, stan dard and double table speed during a volumetric scan. The low-dose tec hnique was implemented in the patient group. Total volume, total Eat a nd four defined compartmental fat volumes in the truncal area were mea sured. Results: The mean fat volume measured using the low-dose CT tec hnique in the phantom was 0.2% above the actual far content. The coeff icient of variation for this method was 5%. Sy using low-dose, double speed instead of standard-dose technique, radiation exposure to the sk in was decreased by more than 90% (equivalent to 4 mGy) of what is use d in diagnostic imaging. The patient scans showed that no significant differences in BMI and total measured volume existed between female an d male patients, but percent far and percent subcutaneous fat were sig nificantly larger in women (P = 0.006 and 0.002, respectively), as wer e percent intraabdominal and mediastinal Eat in men (P = 0.002 and 0.0 03 respectively). Conclusions: Low-dose spiral CT accurately measures fat volume in vitro, and can be used in vivo for compartmental fat mea surements.