Objective: This feasibility study was undertaken to compare the sensitivity of Tc-99m dextran with that of Tc-99m human immunoglobulin G to diagnose ulcerative colitis, and to explore its possible role in disease follow-up.

Methods: Twenty-six patients with active disease and six patients in remission underwent serial Tc-99m dextran scanning for as long as 3 hours or more after injection. Eight of the patients with active disease also underwent Tc-99m human immunoglobulin G imaging.

Results: Twenty-four of 26 (92%) patients with active ulcerative colitis had a positive result of the Tc-99m dextran study, mainly within 1 hour. In comparison, Tc-99m human immunoglobulin G accumulated abnormally in four of eight (50%) patients and had a relatively poor target localization with high persisting background even after 6 hours. Four of the six patients in remission still had a positive result of the dextran scan, but the abnormal uptake was less than that in the patients with active disease. The disease has recurred already in one of these patients. A patient with pancolitis who was receiving steroid enema therapy had intense uptake of Tc-99m dextran in the ascending colon, probability because it was outside the range of the enema.

Conclusions: Tc-99m dextran is a sensitive and cost-effective agent to diagnose ulcerative colitis, and it may have a role in disease follow-up.