A Novel Method in Conventional Dynamic Kidney Scintigraphy: Dynamic 99mTc-MAG3 SPECT/CT

To introduce a novel technique, dynamic ^99 mTc-MAG3 SPECT/CT (DyMAG3 SPECT/CT, SPECT; Single-photon emission computed tomography), which provides detailed anatomical structure, drainage patterns, presence of scarring, and split renal function in a single imaging session. This method seeks to improve the quality of conventional planar scintigraphy and offer comprehensive diagnostic convenience.

DyMAG3 SPECT/CT was applied to nine index cases diagnosed with conditions such as ureteropelvic junction obstruction, ureterovesical junction obstruction, or hydronephrosis resembling ureteropelvic junction obstruction, with or without renal parenchymal thinning. Imaging was conducted just before planned pyeloplasty or ureteroneocystostomy. After a 0.1 mCi/kg ^99 mTc-MAG3 bolus injection, planar perfusion imaging was performed at 2 seconds per frame for 1 minute. Subsequently, 2-minute-per-cycle SPECT acquisitions were undertaken over 20 minutes, followed by a CT acquisition. Time-activity curves (TACs) were generated from the isolated kidney volumes of interest. Split renal functions were calculated by integrating each kidney's time-activity curve between 2 and 4 minutes, emulating conventional ^99 mTc-DMSA scintigraphy.

Preliminary findings from the first nine cases revealed that DyMAG3 SPECT/CT could provide both anatomical and functional data obtained equivalent to conventional techniques in a single imaging session. Moreover, DyMAG3 SPECT/CT improved the diagnostic abilities of ^99 mTc-MAG3 scintigraphy by clearly distinguishing renal parenchyma from the collecting system. This allowed for voxel-based calculation of split renal function as an alternative to ^99 mTc-DMSA scintigraphy.

This preliminary study suggests that DyMAG3 SPECT/CT could emerge as a state-of-the-art tool for the preoperative evaluation of obstructive uropathies.