Pethidine-augmented white cell scintigraphy in inflammatory bowel disease

Technetium-99m hexamethylpropylene amine oxime (Tc-99m-HMPAO) white cell sc intigraphy is invaluable for assessing the presence and extent of disease a ctivity in patients with inflammatory bowel disease. Interpretation of imag es can be compromised by physiological excretion of tracer into the bowel v ia the biliary tree. This study assesses the effect of intravenous pethidin e administered with the labelled white cells in an attempt to reduce the en terohepatic circulation of the tracer. Ninety-one subjects with proven or s uspected inflammatory bowel disease were included in this study, all of who m underwent Tc-99m-HMPAO white cell scintigraphy. The control group of 50 s ubjects underwent the standard protocol for this study performed in our dep artment. The other 41 subjects received an intravenous injection of 0.3 mg/ kg of pethidine at the same time as re-injection of the labelled white cell s. Images were graded using a five-point scale at both 1 and 2.5 h and cate gorised as positive, negative or non-diagnostic. Each scan was also assesse d for the presence of a visible gall-bladder. The pethidine group had signi ficantly fewer non-diagnostic scans than the control group (P=0.003), and s ignificantly (P=0.001) more studies in which the gall-bladder was visualise d, II is concluded that the use of pethidine appears to reduce biliary excr etion of tracer during Tc-99m-HMPAO white cell scintigraphy. This may allow the delayed images, and early images with low-grade tracer uptake in the b owel, to be interpreted with greater confidence and thereby reduce the numb er of scans classified as non-diagnostic.