ABSTRACT
Gd-containing contrast agents and then early qualitative and semi-quantitative techniques of analysis (enhancement patterns and Area Under the Curve) are described. Tracer kinetic modelling is analysed systematically. The principle models estimate the transfer constant Ktrans, blood–brain permeability PS, blood flow F and extravascular extracellular space (EES). The Tofts model provides Ktrans and EES, but neglects blood volume; in the case of high PS, Ktrans=F; if PS is low, then Ktrans=PS. The extended Tofts model attempts to take account of and estimate blood volume. The Patlak model allows a simpler analysis in the case of a small leak analysed early after injection of the contrast agent Data a. The two-compartment exchange model (2CXM) provides a more general approach, and in the right, circumstances can estimate PS and F independently. Acquisition requirements are discussed; these include spatial and temporal resolution, T1 determination and determination of the arterial input function. Sources of error can include signal nonlinearity, water exchange, AIF measurement and haematocrit value. Clinical applications in multiple sclerosis, stroke and tumours are summarised. There are nearly 100 references in this chapter.
