Brain Tumor Imaging with Iopamidol CEST MRI: In Vivo Detection and Validation

TL;DR

This study shows that Iopamidol, a CT contrast agent, can detect brain tumors in mice using CEST MRI with performance similar to traditional gadolinium-based agents.

Contribution

The study provides the first in vivo validation of Iopamidol as a CEST MRI contrast agent for brain tumor detection in a murine model.

Findings

Iopamidol provided comparable tumor detection to Gadoteridol in glioblastoma murine models.

Iopamidol showed 2.7-fold higher lesion-to-brain ratio than Gadoteridol.

Diagnostic accuracy metrics indicated strong similarity between Iopamidol and Gadoteridol in tumor delineation.

Abstract

Several diamagnetic CEST (chemical exchange saturation
transfer)
molecules have been proposed as a potential alternative to gadolinium-based
contrast agents (CAs), with promising contrast efficiency properties.
However, a direct comparison of CEST contrast agents in brain tumors,
where gadolinium CAs are considered the gold standard for detecting
primary masses, is still lacking. The aim of this study is to investigate
the capability of Iopamidol, a CT contrast medium, to detect and delineate
brain tumors in mice using the MRI-CEST technique compared with a
conventional gadolinium-based contrast agent. Iopamidol provided enough
contrast enhancement to detect and delineate brain tumors in both
postinjection and contrast-enhanced images, comparable to Gadoteridol,
in a glioblastoma murine model obtained upon stereotaxic injection
of GL261 cells into C57BL/6 mice. Quantitative comparison between
tumor and healthy tissue was assessed with contrast-to-noise ratio
(CNR) and lesion-to-brain ratio (LBR) metrics. LBR values were 2.7-fold
larger for Iopamidol than for Gadoteridol, although the CNR values
were lower. The diagnostic accuracy of segmented tumor regions on
both Iopamidol- and Gadoteridol-derived contrast images was calculated
by the Tanimoto, DICE similarity, and volume similarity coefficients
that indicated strong similarities between the contoured regions from
Iopamidol and Gadoteridol contrast images. Moreover, moderate to excellent
agreements were observed for intra- and interobserver variability.
Overall, Iopamidol showed a capability similar to that of Gadoteridol
to detect and contour the tumor area, with good diagnostic performance
in terms of tumor border delineation in brain tumors.

Figures