Novel Quantification Protocol for Cardiovascular Calcification Progression Using Longitudinal MicroPET/MicroCT Images

Summary

This novel protocol entails the quantification of cardiovascular calcification progression from serial micro positron emission tomography (PET)/micro computed tomography (CT) images in small research animals.

Abstract

Micro positron emission tomography (PET) and micro computed tomography (CT) imaging are powerful, ideal research tools for following the progression of cardiovascular calcification. Due to their non-invasive nature, small research animals can be imaged at multiple time points. The challenge lies in the accurate quantification of cardiovascular calcification. Here, we provide a protocol, using images from the later disease stages as a template, to accurately quantify the progression of cardiovascular calcification in longitudinal studies. The protocol involves 1) the alignment of the chest area in multiple images from the same animal during a longitudinal study as the first step, 2) the definition of a region of interest (ROI) situated within the heart and the aorta at the site of larger calcium deposits that become apparent in later images, and 3) simultaneous segmentation and quantification of calcium deposits across all images acquired during the longitudinal study. This streamlined method enhances the accuracy of image analysis in following the progression of cardiovascular calcification by improving the precision of ROI definition and reducing the variability associated with earlier techniques that analyze individual scans independently.

Introduction

Cardiovascular disease is a leading global cause of morbidity and mortality, demanding rigorous exploration to uncover its mechanisms and to devise effective preventive and therapeutic strategies. Coronary artery calcification (CAC) is widely acknowledged by the experts in the field as a predictive factor for cardiovascular disease, significantly elevating the risk of cardiovascular mortality^1,2,3,4,5. Microscopic calcifications are considered the earliest stages of calcific atherosclerosis, and the term &#....

Protocol

The representative images present a female apolipoprotein-E-deficient (Apoe^-/-) mouse. Experimental protocols were reviewed and approved by the Institutional Animal Care and Use Committee of the University of California, Los Angeles.

1. Animal scanning

1. Between the two image acquisitions, feed the mouse with a standard diet without any intervention. However, prior to the first image at 15 months of age, switch to a Western diet (21% fat, 0.2% cho.......

Discussion

This novel protocol is an improved approach to the quantification of cardiovascular calcification. Due to the non-invasive nature of imaging, longitudinal microCT images may be acquired to follow the progression of cardiovascular calcification in small animals. Although microCT images alone can show the progression of calcium content, microPET images, when available, can provide additional levels of information, especially its enhanced detection of small calcium deposits due to tracer binding to surface area. For further.......

Materials

Name	Company	Catalog Number	Comments
0.5 cc Sterile Insulin Syringes	Exel International	#26028	Used for IV injection of 18F-NaF PET Tracer
18F-NaF PET Tracer	CNSI Cyclotron
Biorender	Biorender		Used for figure 1
Female Apoe-/- mouse	Jackson Laboratories	#002052	B6.129P2-Apoetm1Unc/J
GNEXT PET/CT	Sofie Biosciences, Dulles, Virginia
Isoflurane	Piramal Critical Care		Used as anesthesia for mouse imaging
ORS Dragonfly	Comet Technologies Canada Inc.
SPSS Statistics	IBM
Western diet for mice	Envigo	#TD88139	21% fat, 0.2% cholesterol