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IMAGE INTERPRETATION · RENAL AND GENITOURINARY

Bilateral Impaired Drainage on MAG3 Renogram

Tc-99m MAG3 renogram curves — both kidneys show a continuously rising pattern throughout the 45-minute study; Left T½ = 80.65 min, Right T½ = 51.73 min
Tc-99m MAG3 renogram curves — both kidneys show a continuously rising pattern throughout the 45-minute study; Left T½ = 80.65 min, Right T½ = 51.73 min

Provided clinical image

Question

On the renogram shown, both kidney curves rise continuously throughout the study and neither kidney reaches a clear peak followed by decline. Left T½ = 80.65 min, Right T½ = 51.73 min. What does this pattern most likely indicate?

  1. ANormal bilateral renal function — the rising curves reflect ongoing tubular secretion of MAG3 and indicate both kidneys are actively processing tracer
  2. BThe patient voided early in the scan, causing a drop in bladder activity that shifted the kidney curves upward artificially
  3. CBoth kidneys have severely impaired drainage — T½ values of 80 and 51 minutes far exceed the normal upper limit of 10 minutes
  4. DThe imaging time was too short — extending the study to 60 minutes would show both curves reaching a peak and beginning to clear normally
Show the answer and explanation

C. Both kidneys have severely impaired drainage — T½ values of 80 and 51 minutes far exceed the normal upper limit of 10 minutes

A normal renogram curve rises to a peak at 2–5 minutes and then declines as tracer drains from the kidney. When both curves continue to rise without ever declining, it means tracer is accumulating in the collecting systems faster than it is draining — indicating bilateral obstruction or severely impaired drainage. A T½ above 10 minutes is abnormal; values of 80.65 and 51.73 minutes are markedly prolonged. A diuretic challenge (furosemide) would typically be administered to confirm true obstruction.

More renal and genitourinary images

Tc-99m MAG3 renal scan acquired with motion correction (MoCo) applied — noted in the window title 'Cine FLOW FUNCTION MoCo MoCo'Motion Correction in MAG3 Renal Scans Tc-99m MAG3 diuretic renogram with Lasix at 21 min — right kidney shows prolonged T½ (85.53 min) with persistent tracer retention and rising renogram curve post-furosemide, indicating UPJ obstructionUPJ Obstruction on MAG3 Diuretic Renogram Tc-99m DMSA renal cortical scan at 30 min and 3 hours (POST, RAO, LAO views) showing focal cortical defect — renal scarring post-pyelonephritisRenal Cortical Scar on DMSA Scan Tc-99m MAG3 qualitative renal scan (0–30 min sequential images) with renogram curves and quantitative parameters for both kidneysNormal Renal Drainage Half-Time on MAG3 Tc-99m MAG3 qualitative renal scan — renogram function curves: left kidney (red dashed), right kidney (green), bladder (purple dotted)Why MAG3 for Renal Imaging: Tubular Secretion Tc-99m MAG3 qualitative renal scan with quantitative parameters: Right T½ = 22.2 min, residual 30 min = 49.4%; Left T½ = 8.1 min, residual 30 min = 15.9%; equal bilateral differential function (51%/49%)Furosemide Dose for Diuretic Renography
← Differential Renal Function on MAG3Motion Correction in MAG3 Renal Scans →

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