Counting glomeruli in human kidney specimens using ex vivo MRI without contrast agents

Area of Science:

• Nephrology
• Medical Imaging
• Biophysics

Background:

• Glomeruli number is key for kidney function assessment.
• Imaging glomeruli with MRI is challenging without contrast agents.
• Previous methods used cationic ferritin, limiting applications.

Purpose of the Study:

• To develop a novel MR microimaging technique for visualizing and quantifying human glomeruli.
• To achieve this without the need for contrast agents.
• To assess the technique's accuracy against established methods.

Main Methods:

• Utilized ultrahigh field (16.4 T) MR microimaging with 3D T1/T2*-weighted gradient-echo sequences.
• Employed a segmentation pipeline for glomeruli identification and counting on MR images.
• Validated counts using unbiased stereology and confocal microscopy.

Main Results:

• Successfully identified glomeruli as hypointense spheres in MR images.
• Demonstrated high spatial concordance between MRI, histology, and confocal microscopy.
• Achieved highly similar glomerular counts between MRI and stereology (r=0.98).

Conclusions:

• High-resolution MR microimaging at 16.4 T enables contrast-agent-free visualization and quantitation of human glomeruli.
• Automated segmentation combined with ultrahigh-field MRI provides accurate glomerular counts.
• This technique offers a promising alternative to traditional methods for ex vivo kidney sample analysis.