High-resolution magnetic resonance imaging to assess bone microarchitecture in patients with chronic kidney disease.

Aim: To validate high-resolution magnetic resonance imaging (HR-MRI) assessment of bone microstructure compared to histomorphometry and micro-CT of bone biopsies from renal transplant recipients. Background(s): Renal osteodystrophy (ROD) affects bone quantity and quality and is associated with increased fractures in chronic kidney disease. Screening for ROD is hindered by complex pathophysiology and inadequacy of current diagnostic methods. Bone biopsy is invasive and infrequently performed in routine practice. HR-MRI is a new imaging technique to assess trabecular and cortical microarchitecture. Method(s): Distal tibia HR-MRI scans (Siemens Trio, 3 T) and iliac crest bone biopsies were performed in 10 transplant recipients at transplantation. Structural parameters of biopsies were analysed by histomorphometry and 3D micro-CT. Structural measures included trabecular bone volume (TV/ BV), thickness (TbTh), number (TbN), separation (TbS), mean cortical thickness (CtTh) and porosity (Po.%). Bone mineral density (BMD) was measured by peripheral quantitative computed tomography (pQCT, radius) and dual energy x-ray absorptiometry (DXA, hip). Associations were determined by analysis with Spearman's rank correlation coefficients. Result(s): HR-MRI (tibia) and micro-CT (iliac crest) indices correlated positively for TbN and TbS (r = 0.52, p = 0.12 and 0.56, p = 0.09 respectively) and TV/BV, with no significant correlation for CtTh at these differing sites. HR-MRI (tibia) CtTh correlated to CtTh and BMD measured by pQCT (radius) (r = 0.65, p = 0.06 and 0.78, p = 0.008 respectively). Micro-CT (iliac) CtTh correlated to BMD by DXA (hip), and cortical porosity by micro-CT correlated negatively to BMD by DXA (r = -0.65, p = 0.04). Conclusion(s): Micro-CT histomorphometry correlates to tibial HR-MRI for important trabecular indices and to hip DXA for cortical indices. Non-invasive HR-MRI and DXA combined with biochemical turnover markers may provide rapid, accessible information t