FET PET for the evaluation of untreated gliomas: correlation of FET uptake and uptake kinetics with tumour grading.

PURPOSE: Treatment and prognosis of gliomas depend on their histological tumour grade. The aim of the study was to evaluate the potential of [(18)F]fluoroethyltyrosine (FET) PET for non-invasive tumour grading in untreated patients. METHODS: Dynamic FET PET studies were performed in 54 patients who, based on MRI, were estimated to have low grade (LG; n = 20), intermediate (WHO II-III; n = 4) or high grade (HG; n = 30) tumours. For standard evaluation, tumour SUV(max) and the ratio to background (SUV(max)/BG) were calculated (sum image: 20-40 min). For dynamic evaluation, mean SUV values within a 90% isocontour ROI (SUV90) and the SUV90/BG ratios were determined for each time frame to evaluate the course of FET uptake. Results were correlated with histopathological findings from PET-guided stereotactic biopsies. RESULTS: Histology revealed gliomas in all patients. Using the standard method a statistically significant difference (p = 0.001) was found between LG (n = 20; SUV(max)/BG: 2.16 +/- 0.98) and HG (n = 34; SUV(max)/BG: 3.29 +/- 1.06) gliomas (opt. threshold 2.58: SN71%/SP85%/area under ROC curve [AUC]:0.798), however, with a marked overlap between WHO II to IV tumours. Time activity curves showed slight increase in LG, whereas HG tumours presented with an early peak (10-20 min) followed by a decrease. Dynamic evaluation successfully separated LG from HG gliomas with higher diagnostic accuracy (SN94%/SP100%/AUC:0.967). CONCLUSIONS: Based on the ratio-based method, a statistically significant difference was found between LG and HG gliomas. Due to the interindividual variability, however, no reliable individual grading was possible. In contrast, dynamic evaluation allowed LG and HG gliomas to be differentiated with high diagnostic power and, thus, should supplement the conventional method.

Chronic high-frequency globus pallidus internus stimulation in different types of dystonia: a clinical, video, and MRI report of six patients presenting with segmental, cervical, and generalized dystonia.

The results of deep brain stimulation (DBS) of the globus pallidus internus (Gpi) in six patients with generalized, focal, and segmental dystonia are presented. Pre- and postoperative assessments are given for one patient with generalized inherited dystonia and for five patients with idiopathic segmental or cervical dystonia. Clinical symptoms were evaluated before and 3-12 months after surgery using the Burke-Fahn-Marsden (BFM) dystonia rating scale for primary torsion dystonia and the Tsui scale for cervical dystonia. The Short-Form Health Survey (SF-36) was completed by each patient to document preoperative and postoperative health status. Also, neurological status was documented by video before and during chronic stimulation. Magnetic resonance imaging studies were performed to show the anatomical localization of the electrode leads. Five patients showed a progressive improvement within 7 days. One patient with cervical dystonia and Meige's syndrome showed no improvement for 3 months, but beneficial effects were observed after 12 months. On average, the BFM movement scale scores decreased by 72.5% and Tsui scale scores by 63%. SF-36 showed an improvement in health status by an average of 36% according to eight different health categories. We conclude that chronic high-frequency Gpi stimulation in different types of dystonia is a very effective and safe treatment.