Search

Quantitative parametric imaging approaches provide new perspectives for radiological imaging. These include quantitative 2D, 3D, and 4D visualization options along with the parametric depiction of biological tissue properties and tissue function. This allows the interpretation of radiological data from a biochemical, biomechanical, or physiological perspective. Quantification permits the detection of small changes that are not yet visually apparent, thus allowing application in early disease diagnosis and monitoring therapy with enhanced sensitivity. This review outlines the potential of quantitative parametric imaging methods and demonstrates this on the basis of a few exemplary applications. One field of particular interest, the use of these methods for investigational new drug application studies, is presented. Assessment criteria for judging the quality of quantitative imaging approaches are discussed in the context of the potential and the limitations of these methods. While quantitative parametric imaging methods do not replace but rather supplement established visual interpretation methods in radiology, they do open up new perspectives for diagnosis and prognosis and in particular for monitoring disease progression and therapy.

Quantitative ultrasound (QUS) methods are promising tools for the assessment of the bone status in osteoporosis. The techniques are based on changes in speed and amplitude of a broadband ultrasound signal propagating through the bone. However, ultrasound propagation through the anisotropic bone is complex and cannot be described in a simple way. The devices are easy to use, inexpensive, portable, do not use ionizing radiation, and therefore have advantages compared to conventional densitometry. This review discusses the technical basics, current research, clinical applications, points of weakness, and future prospects of QUS. For better understanding ultrasound propagation through bone is visualized with a simulation software.

In recent years Quantitative Ultrasound (QUS) approaches have increasingly been used for the assessment of osteoporosis. Extensive study results exist for the estimation of osteoporotic fracture risk. Also, results exist for the analysis of properties which characterize osteoporosis--low bone mass and deterioration of bone architecture. However, the existence of different methods, devices and parameters has to be taken into account. Moreover, the status of the evaluation is different for each type of device. Measures of quality assurance and in-depth knowledge about limitations of the approach are of substantial importance for clinical use. Because of the lack of ionising radiation and their lower cost, QUS approaches--if used appropriately--can play an important role in the assessment of osteoporotic fracture risk.

The rapid development of Quantitative Ultrasound (QUS) methods in recent years allows to use these devices in a clinical setting. Their primary role is the assessment of fracture risk due to osteoporosis. Further investigations are required for use of QUS for monitoring and diagnostic purposes. Differences between the QUS parameters, Speed of Sound (SOS) and Broadband Ultrasound Attenuation (BUA), between different measurement sites and measurement technology need to be appreciated. Consequently, QUS devices need to be validated individually. In addition, adequate quality assurance measures need to be implemented. QUS and bone densitometry have different complementing features and both should find their place in the clinical arena. These recent developments open up the opportunity to reduce the number of fractures by targeted diagnostic assessments which should lead to medical progress and should also bring along socio-economical advantages.