Evaluation of Cortical Bone by Peripheral Quantitative Computed Tomography in Renal Transplant Recipients

Negri, Armando; Lombas, Carola; Cuevas, Carlos; Schiavelli, Rubén; Bogado, César E.; Zanchetta, José R.

doi:10.1016/j.transproceed.2004.12.056

Cited by 19 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Spine QCT data in CKD confirmed biopsy histomorphometric data: trabecular vBMD was increased in highturnover disease (+1.6 SD) and decreased in low-turnover disease (−1.2 SD) relative to age-matched controls [55]. A recent pQCT study in 12 adult transplant recipients demonstrated a significantly greater endosteal circumference and lower cortical thickness compared with controls [56]. Total time on dialysis prior to renal transplantation correlated negatively with cortical thickness (r=0.62; p<0.01).…”

Section: Posterior-anterior Lateralmentioning

confidence: 56%

A structural approach to the assessment of fracture risk in children and adolescents with chronic kidney disease

Leonard

2007

Pediatr Nephrol

View full text Add to dashboard Cite

Children with chronic kidney disease (CKD) have multiple risk factors for impaired accretion of trabecular and cortical bone. CKD during childhood poses an immediate fracture risk and compromises adult bone mass, resulting in significantly greater skeletal fragility throughout life. Highturnover disease initially results in thickened trabeculae, with greater bone volume. As disease progresses, resorption cavities dissect trabeculae, connectivity degrades, and bone volume decreases. Increased bone turnover also results in increased cortical porosity and decreased cortical thickness. Dual-energy X-ray absorptiometry (DXA)-based measures of bone mineral density (BMD) are derived from the total bone mass within the projected bone area (g/cm 2 ), concealing distinct disease effects in trabecular and cortical bone. In contrast, peripheral quantitative computed tomography (pQCT) estimates volumetric BMD (vBMD, g/cm 3 ), distinguishes between cortical and trabecular bone, and provides accurate estimates of cortical dimensions. Recent data have confirmed that pQCT measures of cortical vBMD and thickness provide substantially greater fracture discrimination in adult dialysis patients compared with hip or spine DXA. The following review considers the structural effects of renal osteodystrophy as it relates to fracture risk and the potential advantages and disadvantages of DXA and alternative measures of bone density, geometry, and microarchitecture, such as pQCT, micro-CT (μCT), and micro magnetic resonance imaging (μMRI) for fracture risk assessment.

show abstract

Section: Posterior-anterior Lateralmentioning

confidence: 56%

A structural approach to the assessment of fracture risk in children and adolescents with chronic kidney disease

Leonard

2007

Pediatr Nephrol

View full text Add to dashboard Cite

show abstract

“…The majority of studies relied on DXA (8,9,23,26,(41)(42)(43)(44)(45)(46); work based on advanced imaging techniques is limited to cross-sectional studies conducted at highly variable time points after transplantation (13,18). For example, there is a disconnect between fracture susceptibility and BMD, which has been ascribed to adverse effects of the disease on bone quality (3,8,9) and differences in the 3D microarchitecture of the bone between allograft recipients relative to their otherwise healthy peers with similar BMD (47).…”

Section: Discussionmentioning

confidence: 99%

“…This prospective study consisted of 24 female (10 postmenopausal; mean age, after transplantation; it demonstrated significant cortical thinning (13).…”

Section: Study Subjectsmentioning

confidence: 99%

Micro–MR Imaging–based Computational Biomechanics Demonstrates Reduction in Cortical and Trabecular Bone Strength after Renal Transplantation

Rajapakse

Leonard²,

Bhagat³

et al. 2012

Radiology

View full text Add to dashboard Cite

Purpose:To examine the ability of three-dimensional micro-magnetic resonance (MR) imaging-based computational biomechanics to detect mechanical alterations in trabecular bone and cortical bone in the distal tibia of incident renal transplant recipients 6 months after renal transplantation and compare them with bone mineral density (BMD) outcomes. Materials and Methods:The study was approved by the institutional review board and complied with HIPAA guidelines. Written informed consent was obtained from all subjects. Micro-MR imaging of distal tibial metaphysis was performed within 2 weeks after renal transplantation (baseline) and 6 months later in 49 participants (24 female; median age, 44 years; range, 19-61 years) with a clinical 1.5-T whole-body imager using a modified three-dimensional fast large-angle spin-echo pulse sequence. Micro-finite-element models for cortical bone, trabecular bone, and whole-bone section were generated from each image by delineating the endosteal and periosteal boundaries. Mechanical parameters (stiffness and failure load) were estimated with simulated uniaxial compression tests on the micro-finite-element models. Structural parameters (trabecular bone volume fraction [BV/TV, bone volume to total volume ratio], trabecular thickness [TbTh], and cortical thickness [CtTh]) were computed from micro-MR images. Total hip and spine areal BMD were determined with dual-energy x-ray absorptiometry (DXA). Parameters obtained at the follow-up were compared with the baseline values by using parametric or nonparametric tests depending on the normality of data. Results:All mechanical parameters were significantly lower at 6 months compared with baseline. Decreases in cortical bone, trabecular bone, and whole-bone stiffness were 3.7% (P = .03), 4.9% (P = .03), and 4.3% (P = .003), respectively. Decreases in cortical bone, trabecular bone, and whole-bone failure strength were 7.6% (P = .0003), 6.0% (P = .004), and 5.6% (P = .0004), respectively. Conventional structural measures, BV/TV, TbTh, and CtTh, did not change significantly. Spine BMD decreased by 2.9% (P , .0001), while hip BMD did not change significantly at DXA. Conclusion:MR imaging-based micro-finite-element analysis suggests that stiffness and failure strength of the distal tibia decrease over a 6-month interval after renal transplantation.q RSNA, 2012

show abstract

“…14 To our knowledge, QCT studies in renal transplant recipients are limited to three studies in children [15][16][17] and one study in adults. 18 These cross-sectional studies were limited by inclusion of transplant recipients at highly variable intervals since transplantation; the largest pediatric study was conducted a mean of 4.9 years after transplantation. 15 Although these studies showed cortical deficits, they could not address progression or recovery given the cross-sectional design.…”

mentioning

confidence: 99%

Bone Density and Cortical Structure after Pediatric Renal Transplantation

Terpstra

Kalkwarf²,

Shults³

et al. 2012

Journal of the American Society of Nephrology

View full text Add to dashboard Cite

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area. At baseline, compared with reference participants, renal transplant recipients had significantly lower mean section modulus and muscle area; trabecular BMD was significantly greater than reference participants only in transplant recipients younger than 13 years. After transplantation, trabecular BMD decreased significantly in association with greater glucocorticoid exposure. Cortical BMD increased significantly in association with greater glucocorticoid exposure and greater decreases in parathyroid hormone levels. Muscle and fat area both increased significantly, but section modulus did not improve. At 12 months, transplantation associated with significantly lower section modulus and greater fat area compared with reference participants. Muscle area and cortical BMD did not differ significantly between transplant recipients and reference participants. Trabecular BMD was no longer significantly elevated in younger recipients and was low in older recipients. Pediatric renal transplant associated with persistent deficits in section modulus, despite recovery of muscle, and low trabecular BMD in older recipients. Future studies should determine the implications of these data on fracture risk and identify strategies to improve bone density and structure. During childhood and adolescence, skeletal development is characterized by increases in trabecular and cortical bone mineral density (BMD) and cortical dimensions. 1 Children with CKD have numerous risk factors for impaired bone acquisition, including growth failure, delayed puberty, malnutrition, acidosis, vitamin D deficiency, muscle deficits, and secondary hyperparathyroidism. Successful renal transplantation corrects many of the underlying abnormalities contributing to bone deficits in childhood CKD. However, immunosuppressive therapies and persistent hyperparathyroidism may impair recovery of bone structure and strength. The risk of fracture among adult renal transplant recipients increases in the months after transplantation and then gradually declines. 2 The

show abstract

Evaluation of Cortical Bone by Peripheral Quantitative Computed Tomography in Renal Transplant Recipients

Cited by 19 publications

References 11 publications

A structural approach to the assessment of fracture risk in children and adolescents with chronic kidney disease

A structural approach to the assessment of fracture risk in children and adolescents with chronic kidney disease

Micro–MR Imaging–based Computational Biomechanics Demonstrates Reduction in Cortical and Trabecular Bone Strength after Renal Transplantation

Bone Density and Cortical Structure after Pediatric Renal Transplantation

Contact Info

Product

Resources

About