High-resolution computed tomography imaging ... - Kidney International

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Thomas L. Nickolas1, Shayan Shirazian1 and Elizabeth Shane2. 1Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, ...

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http://www.kidney-international.org & 2010 International Society of Nephrology

Kidney International (2010) 77, 1046; doi:10.1038/ki.2009.558

High-resolution computed tomography imaging: a virtual bone biopsy Thomas L. Nickolas1, Shayan Shirazian1 and Elizabeth Shane2 1

Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, New York, USA and 2Division of Endocrinology, Columbia University College of Physicians and Surgeons, New York, New York, USA Correspondence: Thomas L. Nickolas, Division of Nephrology, Columbia University Medical Center, 622 W 168th Street, New York, New York 10032, USA. E-mail: [email protected]

Figure 1 | HRpQCT image of distal radius and transiliac crest bone biopsy. (a) Ultra high-resolution peripheral quantitative computed tomography (HRpQCT) of the distal radius (left). (b) Transiliac crest bone biopsy (right). The red arrow represents trabecular bone microarchitecture, which was unremarkable. The black arrow represents cortical bone, which is severely deteriorated.

A 63-year-old post-menopausal Caucasian woman presented for kidney-related bone disease evaluation. She had a history of hypertension and remote tobacco use. Intact parathyroid hormone (iPTH) and calcium levels had been normal for 2 years before presentation (range: iPTH 31–64 pg/ml; calcium 2.25–2.52 mmol/l; reference ranges 10–65 pg/ml and 2.15–2.55 mmol/l, respectively). Physical examination was unremarkable. Laboratories showed a serum creatinine level of 97.2 mmol/l, Modification of Diet in Renal Disease estimated glomerular filtration rate of 53 ml/min, iPTH 30.1 pg/ml, 25D 119.8 nmol/l, 1,25D 59.8 pmol/l, and calcium 2.35 mmol/l. Lateral spine films showed fracture of the L5 vertebra. Dual-energy X-ray absorptiometry (DXA) revealed T-scores of 1.5, 1.3, and þ 0.1 at the lumbar spine, total hip, and one-third radius (1/3R), respectively. Ultra high-resolution peripheral quantitative computed tomography (HRpQCT, XtremeCT, Scanco Medical AG) was performed at the distal forearm, which, in comparison with a reference population of premenopausal Caucasian women, showed decreased cortical density

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(781 mgHA/cm3) and thickness (0.66 mm) (reference mean (s.d.): cortical density 940 (62) mgHA/cm3 and thickness 0.90 (0.17) mm) (Figure 1a). Trabecular microarchitecture was unremarkable. Transiliac crest bone biopsy confirmed severe cortical thinning, trabecularization of the endosteal cortex (Figure 1b), and normal trabecular microarchitecture. DXA resolution is too low to discriminate trabecular from cortical bone. DXA measurements of the 1/3R, composed of 95% cortical bone, are considered to reflect the cortex. Similarly, DXA measurements of the lumbar spine, a predominantly trabecular site, are considered to reflect the trabecular bone. HRpQCT is a novel, high-resolution technique (B82 mm) that discriminates cortical from trabecular bone and provides information on trabecular microarchitecture. In this patient, the normal 1/3R T-score suggested that the cortical bone was normal, a fact belied by both the HRpQCT scan and the bone biopsy. This novel imaging technology has the potential to assist in the clinical management of bone disease in patients with chronic kidney disease.

Kidney International (2010) 77, 1046

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