Fig. 2.
Case study: Suspected sampling error. A 62-year-old patient with glioblastoma, treated with subtotal tumor resection (STR) and Stupp. Eight months after radiotherapy, MRI showed a mixed response with regression of the contrast-enhancing necrotic tumor process (shown) and increased T2/FLAIR changes (not shown) in the left-sided frontal lobe, overall suggesting tumor progression.18F-FET PET showed marked uptake in the left orbitofrontal region, indicating tumor recurrence with TBRmax of 2.7 and BTV of 29 cm3. Patient underwent an STR a month later with a histopathology revealing predominantly reactive changes and only insignificant amount of glioblastoma tissue. Patient had an unfavorable outcome with clinical progression only 2 months and death 6.5 months after18F-FET PET. (Left) Preoperative MRI, (middle)18F-FET PET, and (right) postoperative MRI. As brain shift was insignificant, postoperative MRI allowed the resected tissue area to be delineated (red border) and projected to preoperative PET (with previous resection delineated with yellow/orange border) to estimate the volume of active tissue resected, which was below 5%, and might not have been in the tissue specimen at histopathological examination.