Purpose <p>To evaluate whether a body surface area (BSA)–based adjusted body weight (AdBW) protocol stabilizes vascular and hepatic parenchymal enhancement during preoperative CT colonography–angiography (CTC-A).</p> Methods <p>This retrospective single-center study included 221 consecutive patients with colorectal cancer who underwent preoperative CTC-A between January 2024 and March 2025. Examinations used either a total body weight (TBW)–based iodine protocol (600 mg I/kg; n = 113) or a BSA-based AdBW protocol (21.74 g I/m²; n = 108), both with a fixed 30-s injection duration. Contrast enhancement and contrast-to-noise ratio (CNR) were measured in the abdominal aorta (AA), superior mesenteric artery (SMA), inferior mesenteric artery (IMA), and hepatic parenchyma. Hepatic enhancement was defined as the attenuation difference between unenhanced and portal venous–phase images. Body weight–dependent variability was assessed using linear regression slopes and body weight–stratified analyses. Qualitative vascular visualization and liver metastasis conspicuity were assessed using a five-point scale by an abdominal radiologist and a colorectal surgeon.</p> Results <p>Regression slopes for the TBW and AdBW protocols were 2.96 versus 0.13 HU/kg for the AA, 3.98 versus −0.39 HU/kg for the SMA, 4.53 versus 0.22 HU/kg for the IMA, and 0.42 versus −0.06 HU/kg for hepatic parenchyma, respectively. The AdBW protocol reduced body weight dependency for all enhancement parameters. In stratified analyses, vascular attenuation remained stable across all body weight groups with AdBW dosing (all p &gt; 0.05). Hepatic enhancement was also more consistent, with median values maintained at approximately 57.5–61.1 HU. Qualitative assessment showed that vascular visualization and liver metastasis conspicuity remained clinically acceptable with the AdBW protocol.</p> Conclusion <p>BSA-based AdBW dosing reduced body habitus–dependent variability in vascular and hepatic enhancement during preoperative CTC-A.</p>