Uses and limitations of venal scintigraphy in venal transplantation monitoring

The value of thrice weekly technetium-99m mercaptoacetyltriglycine renograp hy after renal transplantation was investigated in 213 consecutive transpla nts. A grading system was used: 0 = normal renogram; 1 = normal uptake, red uced excretion; 2 = normal uptake, flat excretion curve; 3 = rising curve; 4 = reduced rate of uptake, rising curve and reduced absolute uptake; 5 = m inimal uptake. The initial renogram grade (RG) was primarily a marker of is chaemic damage, being poorer with cadaver donation, long cold ischaemia (>2 4 h), and high donor and recipient age. High primary RG predicted primary g raft non-function, long time to graft function, low discharge Cr EDTA clear ance and low 1- and 5-year graft survival. Discharge RG predicted late (>6 months) graft loss. RG was highly correlated (P<0.001) with creatinine and creatinine clearance, and changes in RG were correlated with changes in ren al function. A change in RG of 0.5 was non-specific, while a change of 1 or more predicted clinical complications in 95% of cases. The negative predic tive value was low (58%). RG change antedated clinical diagnosis in only 38 % of cases, and in only 14% of acute rejections did an RG change of 1 or mo re antedate a rising creatinine. RG did not contribute to the differential diagnosis between acute rejection, acute tubulointerstitial nephropathy and cyclosporine toxicity. In conclusion, an initial renography after transpla ntation is valuable as it measures ischaemic damage and predicts duration o f graft nonfunction and both short and long-term graft survival. A review o f the literature suggests that the indication for serial scintigraphic moni toring for functioning grafts is less certain: the diagnostic specificity i s insufficient for it to be the definitive investigation for common diagnos tic problems and it does not give sufficient advance warning of impending p roblems.