Interpreting a DTPA Renogram

Core Interpretation Parameters

The American College of Cardiology recommends assessing relative uptake between kidneys at early time points to evaluate differential function 1, 2
The American College of Cardiology suggests evaluating kidney size, shape, and position on sequential images to detect anatomical abnormalities or parenchymal disease 1, 2
The American College of Cardiology advises identifying transit abnormalities from renal cortex to renal pelvis and bladder to detect parenchymal disease and delays in transport from the renal pelvis 1, 2
Time-activity curves should be generated over each kidney to demonstrate relative uptake and excretion in a semi-quantitative manner, according to the American College of Cardiology 1, 2

The American College of Radiology states that T1/2 drainage time >20 minutes after furosemide administration indicates obstruction 3, 4
Persistent nephrogram without excretion characterizes an obstructive pattern, as noted by the American College of Radiology 4
A normal post-captopril renogram makes hemodynamically significant renal artery stenosis unlikely, according to the American College of Cardiology 1, 2

DTPA is excreted by glomerular filtration, making it useful for estimating single-kidney GFR, as stated by the American College of Radiology 5, 6
The American College of Radiology notes that DTPA has limitations in patients with reduced renal function, where it may produce equivocal or false-positive results compared to MAG3 5, 4
MAG3 is preferred over DTPA for obstruction evaluation due to more efficient tubular extraction and easier washout assessment, according to the American College of Radiology 5, 4

Dehydration can mimic obstruction by causing delayed excretion without true mechanical blockage, as noted by the American College of Radiology 6
Poor renal function (GFR <15-20 mL/min) limits interpretation due to inadequate tracer uptake and prolonged background activity, according to the American College of Radiology 5, 6
Results must be interpreted with clinical findings and other imaging studies, as renograms are sensitive but often lack specificity for exact diagnoses, as stated by the American College of Radiology 6