Quality assurance of imaging techniques used in the clinical management of osteoporosis

Abstract

Recent advances in the densitometric and imaging techniques involved in the management of osteoporosis are associated with increasing accuracy and precision as well as with higher exposure to ionising radiation. Therefore, special attention to quality assurance (QA) procedures is needed in this field. The development of effective and efficient QA programmes is mandatory to guarantee optimal image quality while reducing radiation exposure levels to the ALARA principle (as low as reasonably achievable). In this review article, the basic QA procedures are discussed for the techniques applied to everyday clinical practice.

Quantitative imaging techniques for the assessment of osteoporosis and sarcopenia

“…DXA, QCT, pQCT, HR-pQCT, MRI and QUS to ensure that accuracy and precision of the devices are consistent with manufacture guidelines (174,175). Accuracy is by definition the ability of a measurement to match the actual value of the quantity being measured and it is expressed in terms of accuracy error; precision, expressed in terms of PE, refers to the degree of reproducibility of repeated measurements under unchanged conditions (176).…”

“…To determine the accuracy of a DXA densitometer, a scan of a phantom of known density (density range and size of normal human spine) should be performed as often as possible (optimally three times a week, in any case, no less than once a week) to assess system calibration; phantom scanning and calibration should be repeated after any service is performed on the densitometer (65,173,174). PE of a DXA examination derives from the summation of inherent machine fluctuations and inaccuracies of the technologists performing the examination; the least significant change (LSC) enables the identification of statistically significant changes in BMD over time and is essential to make sure that any change observed in BMD measurement is real and not due to machine or to operator variability (176); the LSC can be calculated from PE using the ISCD precision calculating tool.…”

“…QA of QCT systems represents as a main topic of investigation and recommendations for equipment specifications, equipment QC tests and radiation safety have been developed (174,180). PE depends on many factors including scanner model, scanning method, operator's skill, patient's positioning, ROI's positioning and collaboration of the patient during the examination; for these reasons, each QCT-center should perform a precision test to determine its PE and calculate LSC (174).…”

“…PE depends on many factors including scanner model, scanning method, operator's skill, patient's positioning, ROI's positioning and collaboration of the patient during the examination; for these reasons, each QCT-center should perform a precision test to determine its PE and calculate LSC (174). In particular, the main source of error in determination of both Ct.BMD and Tb.BMD is represented by the partial volume effect.…”

“…In ultrasound examinations, PE results from different factors, including incorrect positioning of the patient, coupling between the transducer and the skin and the effect of soft tissue properties (174). A constant check of the correct functioning of the probes and calibration of ultrasound signal emitted are mandatory to ensure the reliability of the technique (157,185).…”