FIGURE 2. Estimation of ß-adrenergic receptor density using graphic method. Experimental protocol includes 2 injections with doses D1* and D2* at times T1 and T2, respectively. Graphic method is based on measurement of 2 plateau levels at end of distribution phase (C1* and C2*). Plateaus are estimated from only portion of PET data (large •), other data (small •) being disregarded by graphic method. Receptor density is obtained from Equation 2. From current data (specific activity = 29,415 MBq/µmol, D1* = 3.09 nmol, D2* = 22.19 nmol) and using vascular fraction of 40%, receptor concentration is estimated at 18.6 pmol/mL.
