Figure 1.
Positron emission tomography measurement of 11C-PBR28 binding.
In the first six scans including scan 1 of patient 1 shown in Figure 1, 11C-PBR28 binding was measured as total distribution volume, VT, using Logan plot [12] based on radioactivity measured by the PET scanner (A, closed circles: perilesional edema in left basal ganglia, open circles: contralateral side with normal MRI) and 11C-PBR28 concentration in arterial plasma measured with radio-high performance liquid chromatography (B). Brain activity decreased to half of the peak in about 60 min indicating that none of the participants including this patient was a low affinity binder [14] to 11C-PBR28. Both the analyses using only area under the curve of brain radioactivity (A) and that using both brain (A) and arterial blood data (B) gave the same increase of 14% in 11C-PBR28 binding indicating that arterial blood sampling was unnecessary.
Figure 2.
MR and PET images of patient 1 following a single perilesional edema episode.
Fluid-attenuated inversion recovery (FLAIR) and gadolinium (Gd)-enhanced T1-weighted MR images at three time points and 11C-PBR28 PET images obtained at two time points. Two lesions are seen, the straight arrow points out a calcification with edema in the left basal ganglion and the curved arrow the edema and calcification in the right centrum semiovale. Although perilesional edema resolved by 01/14/2008, 11C-PBR28 PET uptake was still present. PET images show 11C-PBR28 binding in total distribution volume, VT. The images are reoriented to show the two lesions on the same coronal slice. Images outside of brain parenchyma are masked.
Figure 3.
MR and PET images of patient 2 who showed a degenerating cyst (arrow).
The patient presented with a seizure 85 days (01/06/2008) before the PET scan on 03/25/2008. On 02/15/2008 when the patient was asymptomatic, MRI scan showed a Gd-enhanced degenerating cyst in right temporal cortex (arrow). On the day of the PET scan (03/25/2008), the Gd-enhanced lesion slightly shrunk, and the PET scan showed increased 11C-PBR28 binding based on Logan plot (21%) and area under the curve (AUC, 17%). The color bar applies to only the PET image on the left side.