Biology subjects

Karjalainen, V.-P.

Publications and source records attributed to Karjalainen, V.-P..

2 recordsLinked to original sources

bioRxiv2025

Characterizing meniscal calcifications with photon counting-based dual-energy computed tomography

Meniscal calcifications are associated with meniscal degeneration and osteoarthritis (OA). However, differentiating between calcification types, such as basic calcium phosphate (BCP) and calcium pyrophosphate (CPP), remains challenging in vivo. Therefore, assessing new imaging possibilities is crucial in understanding the calcification pathologies and their relationship with OA. This study investigated dual-energy computed tomography combined with a photon counting detector (PCD-DECT) to identify calcifications in human meniscal samples ex vivo, using Raman spectroscopy as reference. 82 meniscus samples from 41 donors were imaged using PCD-DECT at 120kVp. Data were collected in two energy bins (20-50keV and 50-120keV) with an isotropic resolution of 37{micro}m. Raman spectroscopy was used to classify the calcifications as BCP or CPP. Among 82 samples, Raman spectroscopy identified 36 samples with only either BCP or CPP calcifications, that were included in the subsequent analysis. Regression models were used to compare the dual-energy index (DEI) and to assess the low energy values for corresponding high energy values between calcification types. The highest difference observed between BCP and CPP in comparison of low energy values for corresponding high energy values was 166HU (95%CI: 73, 259) at high energy value of 500HU and the difference between DEI values was 0.035 (95%CI: 0.011, 0.059), suggesting a potential difference in the measured parameters of calcification types. To conclude, PCD-DECT allowed the measurement of BCP and CPP calcifications ex vivo, offering new potential in vivo applications in the future, which could help understand calcification processes and evaluate the efficacy of disease-modifying drugs targeting calcification inhibition.

bioengineering↗

bioRxiv2023

Age and anatomical region related differences in vascularization of the porcine meniscus using micro-computed tomography imaging

Meniscal lesions in vascularized regions are known to regenerate while lack of vascular supply leads to poor healing. Here we developed and validated novel methodology for three-dimensional structural analysis of meniscal vascular structures with high-resolution micro-computed tomography ({micro}CT). We collected porcine medial menisci from 10 neonatal (not-developed meniscus, n-) and 10 adults (fully developed meniscus, a-). The menisci were cut into anatomical regions (anterior horn (n-AH & a-AH), central body (n-CB & a-CB), and posterior horn (n-PH & a-PH). Specimens were cut in half, fixed, and one specimen underwent critical point drying and {micro}CT imaging, while other specimen underwent immunohistochemistry and vascularity biomarker CD31 staining for validation of {micro}CT. Parameters describing vascular structures were calculated from {micro}CT. The vascular network in neonatal spread throughout meniscus, while in adult was limited to a few vessels in outer region, mostly on femoral side. a-AH, a-CB, and a-PH had three, five, and seven times greater vascular volume than neonate, respectively. Moreover, thickness of blood vessels, in three regions, was six times higher in adult than in newborn. Finally, a-PH appeared to have thicker blood vessels than both a-AH and a-CB. For the first time, critical point drying-based {micro}CT imaging allowed detailed three-dimensional visualization and quantitative analysis of vascularized meniscal structures. We showed more vascularity in neonatal menisci, while adult menisci had fewer and thicker vascularity especially limited to the femoral surface which is involved in load transmission response, thus suggesting how nutritional support in this area of the outer zone is more necessary.

biophysics↗