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Renogram Clinical Applications99mTc-DTPA RENOVASCULAR HYPERTENSION
Female, 34 year old, with severe hypertension, high renin level, underwent captopril renography in posterior view. Twenty min images, at left (1) baseline study shows left kidney with smaller size, diminished uptake and lower and flatter renogram. Relative function is = 41%. At right and 1 h after 50 mg of oral captopril, left kidney presents parenchymal retention (greater than at right side compared to basal image) and the curve is going upward until the end of acquisition. Relative function drops to = 34%. Renal graft revascularization (saphenous) was effective and hypertension could be controlled more easily. R= right, L= left and B=bladder. Right kidney is normal at perfusion, uptake and during excretion and similar in both baseline and after captopril. The renogram is completely normal in the right kidney and does not change from baseline to captopril.
Angiography revealed bilateral fibromuscular dysplasia with severe stenosis at left and right hilar aneurysm.
Hackländer et al, assessed 60 patients finding between fMRI and scintigraphy an accuracy, a sensitivity, and a specificity of 69%, 5%, and 92%, respectively, and correlations between MRA and DSA of 95%, 92%, and 96%. The noninvasive MRA can replace DSA in the diagnosis of renal artery stenosis. However, fMRI can not replace renal scintigraphy (1).
Acosta et al., using 99mTc-DMSA, considered positive for renovascular hypertension studies with decrease of more than five percentual points in unilateral renal function or a new defect absent in baseline study. Renal scintigraphy with captopril demonstrated sensitivity of 60%, specificity of 91%, positive predictive value of 60% and negative predictive value of 91%. We identified 3 patients with segmental defects of uptake consistent with chronic pyelonephritis scarring (2).
Reference:
1 Hackländer T, Mertens H, Stattaus J, Lürken M, Lerch H, Altenburg A, Rautenbach J, Cramer BM. Evaluation of renovascular hypertension: comparison of functional MRI and contrast-enhanced MRA with a routinely performed renal scintigraphy and DSA. J Comput Assist Tomogr. 2004 Nov-Dec;28(6):823-31.
2 Acosta Gómez MJ, Llamas Elvira JM, Rodríguez Fernández A, Gómez Río M, López Ruiz JM, Muros De Fuentes MA, Moral Ruiz A, Ramírez Navarro A. Diagnosis of renovascular hypertension by pre- and post-captopril renal scintigraphy with 99mTc-DMSA. Rev Esp Med Nucl. 2001 Dec;20(7):537-43.