SLOW BOLUS INJECTION OF RIBOSE IN THE IDENTIFICATION OF TL-201 REDISTRIBUTION FOLLOWING COMBINED ADENOSINE DYNAMIC EXERCISE STRESS/

Aim A simple stress/redistribution thallium-201 myocardial perfusion i maging protocol may underestimate the degree of thallium redistributio n in a defect identified on the stress images, We sought to investigat e whether a slow-bolus injection of D-ribose improves the identificati on of thallium redistribution following combined adenosine/dynamic exe rcise stress. Materials and methods Fifteen patients (10 males, five f emale, median age 63 years, range 50-75) were enrolled in the study. A ll underwent two successive adenosine plus exercise myocardial perfusi on scintigraphy protocols 7-14 days apart. Adenosine was infused al 14 0 mu g.kg(-1).min(-1) coupled with 25 W ergometer pedalling for 6 min with 74 Mbq of thallium-201 being injected at 4 min. Immediately follo wing the stress image acquisition. patients received the one of either 60 mg.kg(-1) of D-ribose or normal saline, injected over 5 min. Redis tribution images were acquired after 4 h, The identical stress procedu re was conducted in the crossover arm of the study, and patients recei ved the alternative test article. SPECT images were visually analysed and scored in a nine segment model by two blinded observers. In additi on, circumferential profile analysis was conducted. Results By visual interpretation 25 segments displayed redistribution of the ribose, but not in the saline study, 14 reversible segments were seen on the sali ne study alone, and IS were seen on both studies (P=ns). In six patien ts ribose identified a greater number of redistributing segments, and in a further six patients saline identified more reversible segments. Comparison of mean values of defect extent severity and percentage rev ersibility scores generated from the circumferential profile analysis showed no significant difference between the two arms of the study. Co nclusion A 5 min bolus injection of D-ribose following combined adenos ine/dynamic exercise stress confers little benefit oil the identificat ion of redistribution of thallium-201. These results differ from those of previous studies which showed that a 30 min infusion of D-ribose f ollowing treadmill exercise significantly enhanced thallium redistribu tion. The duration of the ribose infusion is likely to be an important factor influencing the effect brought to bear on the redistribution o f the tracer, and should be run over 30 min, or longer.