Lateral Posterior Method for Depth Correction while Using the Gates Protocol for GFR Estimation: Is it Comparable to...

Area of Science:

• Nephrology
• Nuclear Medicine
• Radiology

Background:

• Glomerular filtration rate (GFR) estimation using the Gates protocol with gamma camera diethylenetriaminepentaacetic acid (DTPA) dynamic renography often shows discrepancies with the gold standard plasma sampling method.
• This inaccuracy is attributed to the general lack of consideration for kidney depth in the standard Gates protocol.
• Investigating manual depth correction methods aims to improve the accuracy of GFR estimation in renography.

Purpose of the Study:

• To evaluate if manual depth correction, specifically using skin-to-kidney distance in lateral view and the posterior aspect-lateral posterior (PALP) method, reduces bias in Gates GFR measurements compared to plasma sampling.
• To compare the effectiveness of two depth correction techniques: direct gamma camera measurement and the PALP method.

Main Methods:

• A retrospective analysis of 27 adult prospective renal donors was conducted.
• Participants underwent both plasma sampling for gold standard GFR and DTPA dynamic renography between January 2022 and April 2023.
• Statistical analysis was performed using SPSS version 21.0.

Main Results:

• No significant agreement was found between plasma sampling GFR and GFR estimated by the gamma camera method with or without lateral posterior depth correction.
• The gamma camera method with depth correction showed a lower systemic bias compared to the lateral posterior method when contrasted with plasma sampling GFR.
• Neither depth correction method adequately reconciled the discrepancies between renographic and plasma-based GFR measurements.

Conclusions:

• The lateral posterior method for depth correction in gamma camera-based Gates protocol GFR estimation is unreliable for adult populations in Western India with preserved renal function.
• Further research is needed to refine GFR estimation techniques in dynamic renography to achieve better correlation with plasma-based gold standards.