Renal dynamic scintigraphy using 3D-ring CZT cameras: comparison with NaI(Tl)

Isotopic renography is pivotal for assessing upper urinary tract obstruction and provides renal functional parameters. New 3D-CZT cameras offer enhanced sensitivity and innovative full SPECT protocols that need to be validated on phantoms. Current renal phantoms are often complex and suitable for 2D imaging. Using a new printed 3D renal phantom, we compared planar and full SPECT dynamic imaging.

A 3D-printed renal phantom mimicking pediatric/adult kidneys was designed. Each kidney subunit, connected to a bladder-bag, was programmably infused with 7.5 MBq of [^99mTc]-Pertechnetate to simulate normal nephrograms. An asymmetry of renal activity was simulated using different activity ratios. Each acquisition was conducted on both conventional NaI(Tl) and 3D-CZT cameras.

The 3D printed phantom enabled the acquisition of consistent and reproducible nephrograms. T_max, T_1/2, and A_{20 - min/max} ratios showed no statistically significant differences between planar and SPECT. Simulated asymmetric renal function demonstrated a strong linear correlation between activity and AUC with r = 0.9455 and 0.9471 (p < 0.0001), respectively for conventional and 3D cameras.

This innovative 3D phantom allowed the acquisition of reproducible nephrograms with parameters comparable to those of clinical examinations. At low activity, 3D-CZT camera acquisitions provided equivalent values to conventional cameras, supporting their use for qualitative imaging and follow-up.