1	BMD Testing Methods
2	Intended Use of Bone Density Testing Osteoporosis is primarily diagnosed by assessing bone mineral density (BMD) BMD can be used to monitor bone density change over time (with or without therapy) BMD can be used to predict the probability (risk) of fractures occurring in the future, the main concern in this disease
3	Bone Density Measurements Actual measurements (x-ray modality): BMD at a measurement point is the mass of bone mineral (mainly calcium) in the path of the radiation beam divided by the cross sectional area of the beam, expressed as g/cm²[area density] For volumetric density, BMD is measured within a 3D volume BMC reflects the total mass of bone mineral (in g) in a region.
4	Diagnostic Numerical Value of BMD From actual BMD measurement to diagnostic numerical value: T-score (& Z-score)
5	WHO Definition T-score -1 to –2.5 is osteopenia T-score less than –2.5 is osteoporosis Presence of fragility fracture indicates severe osteoporosis
6	T-scores and Osteoporosis The current definition of osteoporosis is based on WHO t-scores using hip DEXA T-scores use manufacturer databases Ethnic and gender specific Not comparable to other devices (efforts to standardize t-scores) Movement toward report of fracture risk rather than t-scores
7	BMD and Fracture Risk
8	Fracture Risk Scientifically, researchers agree that: The t-score WHO criteria for diagnosing Osteoporosis is rigid and does not account for variabilities related to different devices and different body sites. Fracture Risk assessment is a better and unbiased indicator for diagnostic purposes. Peripheral devices can be used to assess fracture risk, probably better than central devices (NORA* trial and other studies) In the BMD services field: Years ago, most organizations agreed that a Fracture Risk indicator must be adopted instead of the current t-score. Recently, the ISCD initiated a proposal to develop an absolute Fracture Risk assessment criteria. The WHO is investigating a practical implementation of this proposal.
9	Precision & Accuracy of BMD Precision relates to the reproducibility of the technique. It determines how often BMD serial measurements can be performed, e.g., in assessing response to therapy Accuracy reflects the ability to measure BMD compared to a gold standard, such as the bone mineral density measured by in vitro ashing of the sample
10	Body Sites for Measuring BMD Axial: Hip Spine Peripheral: Forearm Fingers Heel Tibia
11	Cortical and Trabecular Bone Cortical bone is the compact layer which forms the outer shell of bones. Trabecular, (also called Cancellous or spongy) bone is a series of thin plates (trabeculae) which form the interior meshwork of bones.
12	Techniques of Measuring BMD Radiographic Absorptiometry (RA) Single & Dual Photon Absorptiometry (SPA & DPA) Single X-ray Absorptiometry (SXA) Dual Energy X-ray Absorptiometry (DXA) Peripheral DXA (pDXA) Quantitative Computed Tomography (QCT) Peripheral QCT (pQCT) Ultrasound Radiogrammetry
13	DXA Strengths Accepted as gold standard; Accurate and precise; and Non-invasive. Weaknesses High cost of equipment ($80-150,000); Need for specially trained technologists; Does not distinguish between trabecular and cortical bone; and Discrepancies of results between hip and spine.
14	QCT Strengths Three dimensional, color analysis; Non-invasive; and Distinguishes between trabecular and cortical bone. Weaknesses High cost of CT scanners; Restricted to measurements at the spine: Considered accurate, but imprecise; High radiation dose; and Need for specially trained technologists.
15	DXA & QCT Two factors play a critical role in obtaining accurate, reproducible DXA and QCT results: The skills and expertise of operators Patient positioning
16	Ultrasound Strengths No radiation; Ease of use- one button operation; Low cost of equipment; Non-invasive; and Portable. Weaknesses Questionable results- low correlation with DXA; Use for screening only; and Need for gel or water application in most devices.
17	Ultrasound 2 The NOF states the following facts about Ultrasound devices: “Inconsistent readings Significant rate of false negatives cannot be used for diagnosis cannot be used to monitor treatment cannot be used to accurately screen women under 65”.
18	RA Strengths Accurate and precise; Good correlation with DXA; Low cost of equipment; Low radiation dose; Ease of use- no special training; Reimbursable procedure; Distinguishes between trabecular and cortical bone; Non-invasive; Works with any standard X-ray; and Adaptable to CR/DR/PACS system. Weaknesses Technology not well known in the clinical market; and Need for X-ray equipment
19	Techniques Comparison
20	BMD device manufacturers 1 Hologic: DXA Fan Beam: Discovery, Delphi & QDR 4500 Series DXA Pencil Beam: QDR 4000 Series US: Sahara (heel) GE-Lunar: DXA Fan Beam: Prodigy Vision, Prodigy Oracle & Prodigy Pro DXA Pencil Beam: DPX Pro US: Achilles InSight, Achilles Express (heel) pDXA: PIXI (heel & forearm) CooperSurgical-Norland: DXA Pencil Beam: Excell & XR-46 US: McCue C.U.B.A. & APOLLO (both heel)
21	BMD device manufacturers 2 Mindways Software, Inc., CIRS, Inc. & Image Analysis, Inc. Developers of QCT software packages Alara, Inc. RA: MetraScan Sunlight Medical, Ltd. US: Omnisense series (forarm, finger & foot) Schick Technologies Inc. pDXA: accuDEXA
22	BMD device manufacturers 3 Sectra-Pronosco: DXR (Digital X-ray Radiogrammetry): X-posure System (hand & forearm) Demetech: DXL (Dual X-ray and Laser): Calscan (heel) Stratec-Medizintechnik: pQCT: XCT 2000 (Forearm & Tibia) Scanco Medical AG pQCT: Densiscan 1000 (Forearm & Tibia)
23	Thank you