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Hypoperfusion of the infrapatellar fat pad and its relationship to MRI T2* relaxation time changes in a 5/6
Guo-Shu Huang1,2, Yi-Jen Peng3, Yu-Juei Hsu4
1Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Abstract:
The purpose of present study was to longitudinally investigate the alterations in infrapatellar fat pad (IPFP) vascularity in 5/6 nephrectomized rats by using dynamic contrast enhanced (DCE) MRI and IPFP degeneration by using MRI T2* relaxation time. Twelve male Sprague-Dawley rats were assigned to a control group and a 5/6 nephrectomy CKD group. The right knees of all rats were longitudinally scanned by 4.7 T MRI, and serial changes in the IPFP were assessed at 0, 8, 16, 30, and 44 weeks by DCE-MRI (parameters A, kel and kep) and MRI T2* mapping. After MRI measurements, knee specimens were obtained and evaluated histologically. The CKD group had IPFPs with lower blood volume A and lower permeability kep values from 16 weeks (p < 0.05), lower venous washout kel value from 30 weeks (p < 0.001), and significantly higher T2* values reflecting adipocyte degeneration beginning at 16 weeks (p < 0.05). The histopathological results confirmed the MRI findings. Hypoperfusion and adipocytes degeneration related to CKD were demonstrated in a rodent 5/6 nephrectomy model. DCE parameters and MRI T2* can serve as imaging biomarkers of fat pad degeneration during CKD progression.
Insights
Chronic kidney disease (CKD) in rats leads to reduced infrapatellar fat pad (IPFP) vascularity and degeneration. Dynamic contrast-enhanced MRI and T2* mapping show potential as biomarkers for fat pad changes in CKD.
Area of Science:
- Biomedical Imaging
- Nephrology
- Orthopedics
Background:
- Chronic kidney disease (CKD) is associated with systemic complications.
- Alterations in connective tissues, including the infrapatellar fat pad (IPFP), may occur in CKD.
- Non-invasive imaging methods are needed to assess these changes.
Purpose of the Study:
- To longitudinally evaluate changes in IPFP vascularity and degeneration in a rat model of CKD.
- To investigate the utility of dynamic contrast-enhanced MRI (DCE-MRI) and MRI T2* relaxation time as imaging biomarkers.
Main Methods:
- A 5/6 nephrectomy model was used in Sprague-Dawley rats (n=12), divided into control and CKD groups.
- Longitudinal MRI scans (4.7T) were performed at multiple time points (0-44 weeks).
- DCE-MRI parameters (A, k_el, k_ep) and T2* mapping assessed IPFP vascularity and degeneration, correlated with histology.
Main Results:
- CKD rats exhibited decreased IPFP blood volume (A) and permeability (k_ep) from 16 weeks.
- Reduced venous washout (k_el) was observed from 30 weeks in CKD rats.
- Significantly increased T2* values, indicating adipocyte degeneration, began at 16 weeks in CKD rats, confirmed by histology.
Conclusions:
- CKD induces hypoperfusion and adipocyte degeneration in the IPFP, as demonstrated in the 5/6 nephrectomy rat model.
- DCE-MRI parameters and T2* mapping are potential imaging biomarkers for detecting fat pad degeneration during CKD progression.
