For the first minute following tracer injection, rapid dynamic imaging evaluates perfusion. The nephrons extract the tracer from the blood and excrete it by glomerular filtration and/or tubular secretion in the second phase. In the third phase, the tracer drainage allows assessment of urinary flow [67]. Although the use of radionuclide renal imaging during the early post-transplantation period has decreased, there are still centers that routinely perform them prior to patient discharge from the hospital to serve as a baseline study for future comparison. An advantage of renography is that it provides functional information, whereas blood creatinine levels lag behind function and radiographic studies are primarily anatomic. Because of this, it can be helpful in evaluating the return of function after ATN or rejection. Yazici et al [68] found scintigraphy performed within 2 days of transplantation was superior to RI in predicting long-term graft function. Heaf et al [69] found that a renogram performed 1 to 2 days after transplantation could predict primary graft nonfunction, prolonged time to graft function, low hospital discharge chromium EDTA clearance, and low 1- and 5-year graft survival, whereas a renogram performed at discharge could predict late (>6 months) graft loss. Although sensitive in the detection of graft dysfunction, scintigraphic parameters do not yield sufficient diagnostic power for a specific diagnosis. Like RI, renogram changes do not contribute to the differential diagnosis between acute rejection, ATN, and cyclosporine toxicity [69,70]. RAS appears similar to the scintigraphic findings seen with rejection. Angiotensin-converting enzyme inhibitor renography can aid in the diagnosis if baseline studies are available for comparison. In obstruction, scintigraphy can be used in conjunction with furosemide, as it is in native kidneys. Urinary leaks can be identified by the presence of radioactivity in an abnormal location.
Renal Transplant Dysfunction. For the first minute following tracer injection, rapid dynamic imaging evaluates perfusion. The nephrons extract the tracer from the blood and excrete it by glomerular filtration and/or tubular secretion in the second phase. In the third phase, the tracer drainage allows assessment of urinary flow [67]. Although the use of radionuclide renal imaging during the early post-transplantation period has decreased, there are still centers that routinely perform them prior to patient discharge from the hospital to serve as a baseline study for future comparison. An advantage of renography is that it provides functional information, whereas blood creatinine levels lag behind function and radiographic studies are primarily anatomic. Because of this, it can be helpful in evaluating the return of function after ATN or rejection. Yazici et al [68] found scintigraphy performed within 2 days of transplantation was superior to RI in predicting long-term graft function. Heaf et al [69] found that a renogram performed 1 to 2 days after transplantation could predict primary graft nonfunction, prolonged time to graft function, low hospital discharge chromium EDTA clearance, and low 1- and 5-year graft survival, whereas a renogram performed at discharge could predict late (>6 months) graft loss. Although sensitive in the detection of graft dysfunction, scintigraphic parameters do not yield sufficient diagnostic power for a specific diagnosis. Like RI, renogram changes do not contribute to the differential diagnosis between acute rejection, ATN, and cyclosporine toxicity [69,70]. RAS appears similar to the scintigraphic findings seen with rejection. Angiotensin-converting enzyme inhibitor renography can aid in the diagnosis if baseline studies are available for comparison. In obstruction, scintigraphy can be used in conjunction with furosemide, as it is in native kidneys. Urinary leaks can be identified by the presence of radioactivity in an abnormal location.