# Temporal Assessment of Gadolinium Deposition and T1 Signal Intensity Changes in Rat Kidney with Single and Multiple Doses of Injection: An Experimental Study

## TL;DR

This study examines how gadolinium accumulates in rat kidneys over time after single or multiple doses and finds that T1 signal intensity is not a reliable indicator of deposition.

## Contribution

The study provides new insights into the temporal dynamics of gadolinium deposition in rat kidneys and challenges the reliability of T1 signal intensity as a measurement tool.

## Key findings

- Gadolinium deposition in rat kidneys increases with the number of injections.
- T1 signal intensity measurements showed poor agreement among observers.
- Deposition levels in the late stage were not significantly influenced by dose or injection frequency.

## Abstract

Gadolinium deposition in biological tissues was first reported in patients with renal failure. We aimed to investigate gadolinium deposition in the rat kidney after exposure to single and multiple doses of gadolinium and evaluate deposition for 1- and 3-month periods. We also aimed to determine any correlation between the amount of deposition and T1-weighted image intensity.

Seventy rats (5 animals per group) were included in the sample, and 9 groups received a single dose (0.3, 0.6, and 1.2 mmol/kg) of gadolinium, and 1 group for each dose was sacrificed at the end of the first day, week, and month. Four groups received weekly doses (0.3 and 0.6 mmol/kg) and were sacrificed at the end of 6 and 12 weeks. Measurement of T1 intensities was carried out with postinjection images before sacrifice, and deposition was determined using inductively coupled plasma mass spectrometry.

The number of injections was associated with increased gadolinium deposition (P < .001) in the kidney. After the weekly injections, the deposited gadolinium levels did not significantly differ between the low and medium doses at the end of the sixth week (P = .067). There was no agreement between the observers regarding the measurement of T1 signal intensity in both single-dose and multidose experiments (P = .263 and P = .307, respectively).

Deposition was dose dependent in the postinjection stage in contrast to the late stage in which deposition was not associated with dose or number of injections until the 12th week. T1 signal intensity measurement is unreliable for assessing deposition in the rat kidney.