FIGURE 6.  ¹⁸F-DOPA coronal view after carbidopa pretreatment in patient with metastasized carcinoid, showing heterogeneity of receptor expression and metabolic activity. (A) ¹⁸F-DOPA PET showing high uptake in entire process. (B) Considerably heterogeneous ¹¹¹In-octreotide uptake. Apparently, medial part of this tumor (arrows) had lost most of its somatostatin receptor expression while retaining metabolic activity and ¹⁸F-DOPA uptake.