Adding Liver Window Setting to the Standard Abdominal CT Scan Protocol: Is It Useful? 65

Background/ Hepatic lesions may be missed in the routine abdominal computed tomography (CT) scan protocol using soft tissue window setting. The ability to find these lesions is very important in the assessment of metastasis and follow-up of patients.Patients and In this study, 411 patients who underwent abdominal CT for various causes were evaluated separately by two radiologists blindly. All liver images were viewed in two different window settings, soft tissue window setting: window width (WW) of 350-400 Hounsfield unit (HU), window level (WL) of 35-50 HU, and liver window setting: WW of 150 HU, WL of 50-100 HU, at the workstation. Out of 411 patients, 181 (44%) were referred for cancer follow-up and 230 (56%) for evaluation of abdominal discomfort. Soft tissue window setting revealed no lesion in 334 (81.26%) patients, single lesion in 30 (7.31%), and multiple lesions in 47 (11.43%) patients. Liver window setting revealed no lesion in 313 (76.2%) patients, single lesion in 35 (8.5%), and multiple liver lesions in 63 (15.3%) patients. Compared to liver window, soft tissue window setting revealed 77.77% of all detectable liver lesions. Liver window showed new lesions in 22 (6.6%) of patients in whom no lesion had been found in soft tissue window setting. Therefore, liver window setting brought 5.3% increase in the diagnostic yield of CT in our series, and changed the decision for treatment in 2.4% of patients studied. Liver window setting added to the standard soft tissue setting protocol of abdominal CT at the workstation can improve the diagnosis and follow-up of patients, especially for those who have known cancer. Image review with this new setting takes a few minutes and the cost is also low; there is no added radiation exposure to patients.