Figure 1c. Patient 3. Transverse CT images obtained with the (a) standard mediastinal (window width, 400 HU; window center, 30 HU), (b) modified (window width, 416 HU; window center, 208 HU), and (c) double-half (window width, 748 HU; window center, 187 HU) window settings. (d) Transverse CT image obtained with the mean value of the personal window setting for all observers (window width, 628 HU; window center, 175 HU). A subtle nonocclusive PE (arrow) in the right upper lobe PA is obscured by apparent intensely enhanced blood, and it becomes invisible at the standard mediastinal window setting. PE is apparent at other window settings.