Correlation of Patient Weight and Cross-Sectional Dimensions with Subjective Image Quality at Standard Dose Abdominal CT Mannudeep K. Kalra, MD, DNB Michael M. Maher, MD, FRCR, FFR (RCSI) Srinivasa R. Prasad, MD M. Sikandar Hayat, MD Michael A. Blake, MRCPI, FFR (RCSI), FRCR Jose Varghese, MD Elkan F. Halpern, PhD. Sanjay Saini, MD Index terms : Computed tomography (CT) Korean J Radiol 2003;4:234-238 Received May 20, 2003; accepted after revision July 11, 2003. All authors: Department of Radiology, Massachusetts General Hospital and Harvard Medical School, U.S.A. Address reprint requests to: Sanjay Saini, MD, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55, Fruit Street, Boston, MA 02114, U.S.A. Telephone: (617) 726-3937 Fax: (617) 726-4891 e-mail: ssaini@partners.org 234 Objective: We evaluated the association between patients’ weight and abdom- inal cross-sectional dimensions and CT image quality. Materials and Methods: We prospectively evaluated 39 cancer patients aged more than 65 years with multislice CT scan of abdomen. All patients underwent equilibrium phase contrast-enhanced abdominal CT with 4 slices (from top of the right kidney) obtained at standard tube current (240 280 mA). All other scanning parameters were held constant. Patients’ weight was measured just prior to the study. Cross-sectional abdominal dimensions such as circumference, area, aver- age anterior abdominal wall fat thickness and, anteroposterior and transverse diameters were measured in all patients. Two subspecialty radiologists reviewed randomized images for overall image quality of abdominal structures using 5- point scale. Non-parametric correlation analysis was performed to determine the association of image quality with patients’ weight and cross-sectional abdominal dimensions. Results: A statistically significant negative linear correlation of 0.46, 0.47, 0.47, 0.58, 0.56, 0.54, and 0.56 between patient weight, anterior abdominal fat thick- ness, anteroposterior and transverse diameter, circumference, cross-sectional area and image quality at standard scanning parameters was found (p < 0.01). Conclusion: There is a significant association between image quality, patients’ weight and cross-sectional abdominal dimensions. Maximum transverse diame- ter of the abdomen has the strongest association with subjective image quality. C sures to patients from medical diagnostic techniques most notably from oncerns have been raised in recent publications about the radiation expo- CT scans (1 4). Studies emphasizing modulation of tube current accord- ing to patients’ weight have been performed in the past (5, 6). However, a systematic analysis of relationship between patients’ thickness parameters and weight and image quality at same tube currents has not been sufficiently investigated. To investigate the significance of these parameters for development of optimum scanning protocols, we evaluated the association of patient’s morphological characteristics including weight and cross-sectional dimensions with subjective image quality with standard CT proto- col (kVp and mAs). MATERIALS AND METHODS We evaluated consecutive 39 subjects aged more than 65 years, with history of can- cer who were referred for abdominal CT study, in an Institutional Review Board (IRB) approved project. The study population consisted of 24 women and 15 men with an Korean J Radiol 4(4), December 2003