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IMAGE INTERPRETATION · RENAL AND GENITOURINARY

Motion Correction in MAG3 Renal Scans

Tc-99m MAG3 renal scan acquired with motion correction (MoCo) applied — noted in the window title 'Cine FLOW FUNCTION MoCo MoCo'
Tc-99m MAG3 renal scan acquired with motion correction (MoCo) applied — noted in the window title 'Cine FLOW FUNCTION MoCo MoCo'

Provided clinical image

Question

This MAG3 scan was acquired with motion correction (MoCo) applied, as noted in the window header. Why is motion correction important during a renal scintigraphy study?

  1. AMotion correction recalculates the T½ values automatically to account for breathing artifacts that occur during the flow phase of the scan
  2. BMotion correction removes bladder activity from the field of view, which would otherwise lower kidney counts during the drainage phase
  3. CMotion correction adjusts the injected dose calculation if the patient shifts position away from the detector during tracer administration
  4. DPatient movement during the scan can shift the kidney outside its region of interest (ROI), causing inaccurate renogram curves and unreliable quantitative results
Show the answer and explanation

D. Patient movement during the scan can shift the kidney outside its region of interest (ROI), causing inaccurate renogram curves and unreliable quantitative results

During a renal scan, the technologist draws regions of interest (ROIs) around each kidney on early frames to generate the time-activity curves (renogram). If the patient moves during the 30–45 minute study, the kidney can shift out of the fixed ROI, causing falsely low counts that create artificially abnormal-looking curves and incorrect quantitative parameters (T½, split function, residual activity). Motion correction software realigns the image frames so that the ROIs remain accurately placed on the kidneys throughout the study, producing more reliable results.

More renal and genitourinary images

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 Direct radionuclide cystogram — sequential bladder filling frames, post-flow total, post-voiding views, and anterior/posterior bladder prevoid imagesDirect Radionuclide Cystogram Technique
← Bilateral Impaired Drainage on MAG3 RenogramUPJ Obstruction on MAG3 Diuretic Renogram →

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