1. Radiotherapy treatment planning and long-term follow-up with [11C]methionine PET in patients with low-grade astrocytoma 
Joanne Nuutinen, M.D., Pirkko Sonninen, M.D., Pertti Lehikoinen, Ph.D., Eija Sutinen, M.D., Ritva Valavaara, M.D., Esa Eronen, Stefan Norrgård, Jarmo Kulmala, Ph.D., Mika Teräs, Heikki Minn, M.D. 
International Journal of Radiation Oncology • Biology • Physics 
Volume 48, Issue 1, Pages (August 2000)
DOI: /S (00)

2. Fig. 1
Positron emission tomography (PET) and T2-weighted MRI images of patient with right temporal low-grade astrocytoma before (A and D) and after (B–C and E–F) radiotherapy (RT). Before RT, the patient underwent an operation thought to be a total resection of all tumor. In the postoperative [11C]-methionine (MET) PET, residual tumor activity can be detected in the frontal part of the right temporal lobe (A, red arrow). Corresponding T2-weighted MRI image (D) shows increased signal intensity throughout the original tumor area (D, red arrow). Likewise, T1-weighted image with gadolinium did not show the residual tumor because of enhancing postoperative scar tissue (image not shown). The MET uptake normalized subsequently in the follow-up PET studies 3 and 6 months after RT, respectively (B–C). The unspecific T2 MRI signal remains high at 3 months (E) and gradually starts to decrease 6 months after RT (F). Note the normal accumulation of MET in lacrimal glands above the tumor area.
International Journal of Radiation Oncology • Biology • Physics  , 43-52DOI: ( /S (00) )

3. Fig. 2
Radiation treatment planning in a patient (Patient 2) with right temporal low-grade glioma. Panels show T2-weighted MRI, [11C]-methionine positron emission tomography (MET PET), and two dose-planning CTs depicting planning target volumes (PTV, upper arrow) delineated without (left) and with (right) PET-aided gross tumor volume (GTV, lower arrow) definition. Increased T2-signal intensity extends close to the cerebral peduncle in MRI, whereas MET PET demarcates more clearly tumor activity around the postsurgical cavity. In this case, PTV defined with PET and MRI was only 60% of that defined using MRI only.
International Journal of Radiation Oncology • Biology • Physics  , 43-52DOI: ( /S (00) )

4. Fig. 3
[11C]-Methionine uptake in glioma before radiotherapy expressed as standardized uptake value (SUV). Pretreatment SUV in tumor is significantly lower in patients who have remained clinically stable in comparison to those who have subsequently died during a median follow-up time of 33 months.
International Journal of Radiation Oncology • Biology • Physics  , 43-52DOI: ( /S (00) )

5. Fig. 4
[11C]Methionine uptake ratio expressed as SUV in tumor versus SUV in seemingly normal contralateral brain tissue. All patients underwent radiotherapy between the first two time points (0 and 3 months). Patients showing no evidence of disease progression (NED) have significantly lower mean uptake ratios than patients having a relapse (AWD, alive with disease) and patients who have died of progressive disease (DOD). Error bars have been omitted to clarify the difference.
International Journal of Radiation Oncology • Biology • Physics  , 43-52DOI: ( /S (00) )