The results of this study suggest that the second derivative spectroscopy offers a practical and more specific method than routinely used absorption spectrum analysis methods to obtain compositional information on AC with FT-IR spectroscopic imaging.

In highly organized tissues, such as cartilage, tendons and white matter, several quantitative MRI parameters exhibit dependence on the orientation of the tissue constituents with respect to the main imaging magnetic field (B0). In this study, we investigated the dependence of multiple relaxation parameters on the orientation of articular cartilage specimens in the B0. Bovine patellar cartilage-bone samples (n = 4) were investigated ex vivo at 9.4 Tesla at seven different orientations, and the MRI results were compared with polarized light microscopy findings on specimen structure. Dependences of T2 and continuous wave (CW)-T1ρ relaxation times on cartilage orientation were confirmed. T2 (and T2*) had the highest sensitivity to orientation, followed by TRAFF2 and adiabatic T2ρ. The highest dependence was seen in the highly organized deep cartilage and the smallest in the least organized transitional layer. Increasing spin-lock amplitude decreased the orientation dependence of CW-T1ρ. T1 was found practically orientation-independent and was closely followed by adiabatic T1ρ. The results suggest that T1 and adiabatic T1ρ should be preferred for orientation-independent quantitative assessment of organized tissues such as articular cartilage. On the other hand, based on the literature, parameters with higher orientation anisotropy appear to be more sensitive to degenerative changes in cartilage.

Renal osteodystrophy alters metabolic activity and remodeling rate of bone and also may lead to different bone composition. The objective of this study was to characterize the composition of bone in high-turnover renal osteodystrophy patients by means of Fourier transform infrared spectroscopic imaging (FTIRI). Iliac crest biopsies from healthy bone (n ¼ 11) and patients with renal osteodystrophy (ROD, n ¼ 11) were used in this study. The ROD samples were from patients with hyperparathyroid disease. By using FTIRI, phosphate-toamide I ratio (mineral-to-matrix ratio), carbonate-to-phosphate ratio, and carbonate-to-amide I ratio (turnover rate/remodeling activity), as well as the collagen cross-link ratio (collagen maturity), were quantified. Histomorphometric analyses were conducted for comparison. The ROD samples showed significantly lower carbonate-to-phosphate ( p < .01) and carbonate-to-amide I ( p < .001) ratios. The spatial variation across the trabeculae highlighted a significantly lower degree of mineralization ( p < .05) at the edges of the trabeculae in the ROD samples than in normal bone. Statistically significant linear correlations were found between histomorphometric parameters related to bone-remodeling activity and number of bone cells and FTIRI-calculated parameters based on carbonate-to-phosphate and carbonate-to-amide I ratios. Hence the results suggested that FTIRI parameters related to carbonate may be indicative of turnover and remodeling rate of bone. ß 2010 American Society for Bone and Mineral Research.KEY WORDS: BONE COMPOSITION; HISTOMORPHOMETRY; FOURIER TRANSFORM; INFRARED; RENAL OSTEODYSTROPHY; CARBONATE B one is a composite material consisting of a mineral phase (hydroxyapatite), an organic phase (collagen), noncollagenous proteins, lipids, and water. (1,2) Metabolic bone disease is a common term referring to a number of abnormalities caused by a broad spectrum of disorders. Most disorders lead to weakening of the bone or impaired bone function and are followed most often by altered bone mechanical properties. Renal osteodystrophy (ROD) is a chronic kidney disease that can be accompanied by different types of bone pathologies. ROD can lead to defective mineralization, altered bone morphology, and/or bone turnover. (3,4) Commonly, it is accompanied by hyperparathyroid disease, which is characterized by increased bone turnover. Patients with renal osteodystrophy may exhibit bone and joint pain, bone deformation, and spontaneous bone fractures. Bone biopsies followed by quantitative histomorphometry prevail as the ''gold standard'' for the diagnosis of renal osteodystrophy. (5)(6)(7) Histomorphometric analysis emphasizes increased amounts of osteoid and erosion surface and a larger amount of bone cells than what is present in normal bone. (8) However, the invasive nature of obtaining the biopsies, the required experience of the pathologists to identify the abnormalities, as well as the lack of standardized normal limits remain problematic.ROD also commonly results in lower bone ...

Articular cartilage is a connective tissue that is located at the ends of long bones. Type II collagen, proteoglycans, water, and chondrocytes are the main constituents of articular cartilage. Osteoarthritis, the most common joint disease in the world, causes degenerative changes in articular cartilage tissue. Fourier transform infrared, Raman, and near infrared spectroscopic techniques offer versatile tools to assess biochemical composition and quality of articular cartilage. These vibrational spectroscopic techniques can be used to broaden our understanding about the compositional changes during osteoarthritis, and they also hold promise in disease diagnostics. In this article, the current literature of articular cartilage spectroscopic studies is reviewed.