Ans. is 'b' i.e., Tc99m - DTPA Renal Scintigraphy1) Static renal scintigraphyo For static renal scintigraphy Tc - 99m - DMSA(Dimercaptosuccinic acid) is used. DMSA is cleared by renal tubules. When DMSA is labeled with Tc - 99 and injected intravenously, it can be used to create an image of the renal cortex which reflects vascular flow and tubular function. It is called static scintigraphy because radiopharmaceutical is tubularly fixed in the renal cortex.o Beside Tc - 99m - DMSA, other radiopharmaceuticals used for static scintigraphy are Tc - 99m - glucoheptone, (Tc-GH)o Indications for static renal scintigraphy (Tc - 99m - DMSA)i) Assessment of individual functionii) Investigation of UTI (particularly in children)iii) Assessment of reflux nephropathy (scars)iv) Space occupying lesions (cortical mass)v) Investigation of horse shoe, solitary or ectopic kidney2) Dynamic renal scintigraphy (functional imaging)o For dynamic renal scintigraphy Tc - 99m - DTPA (Diethylene triamine pentaacetic acid) and Tc - 99m - MAG 3 (mercaptoacetyltriglycine) and I - 123 - OIH (O - iodohippurate) are used.o Tc - 99m - DTPA is filtered completely by the glomerulus but are not reabsorbed, metabolized or secreted by renal tubules. Therefore this agent can be used to measure GFR.o Tc - 99m - MAG3 and I - 123 - OIH are secreted by renal tubules. These are used to determine effective renal plasma flow.o Tc - 99m - MAG3 is the best (amongst three) for dynamic renal scintigraphy, but is costly.o This is called dynamic scintigraphy because tracers are readily transported either by glomerulus or renal tubules (in contrast to static scintigraphy, where tracer is tubularly fixed in the renal cortex).o Indications of dynamic renal scintigraphy :-i) Diagnosis of obstructed vs non - obstructed dilatationii) Diagnosis of renal artery stenosisiii) Assessment of perfusion in ARFiv) Demonstration of vesico-urethral refluxv) Assessment of renal transplantationvi) Renal trauma