FET PET reliably distinguishes between post-therapeutic benign lesions and tumour recurrence after initial treatment of low- and high-grade gliomas.

For patients with gliomas undergoing multimodal treatment or various forms of irradiation, conventional follow-up with MRI is insufficient to distinguish between benign side effects of therapy and tumor recurrence. FET-PET is a powerful tool to improve the differential diagnosis in these patients.

Meningiomas are known to express somatostatin receptor 2 (SSTR2). PET using the SSTR2 analog 68 Ga-DOTATATE has recently been introduced for imaging of meningiomas. However, a systematic correlation between 68 Ga-DOTATATE uptake, SSTR2 expression, and histology (including tumor-free scar tissue) is still lacking. For elucidation, we conducted this prospective study. Methods: Twenty-one adult patients with primary (n 5 12) or recurrent (n 5 9) meningiomas were prospectively enrolled. Preoperative MR imaging and 68 Ga-DOTATATE PET scans were fused and used for a spatially precise neuronavigated tissue-sampling procedure during tumor resection. Histopathologic diagnosis included immunohistochemical determination of SSTR2 expression. At each individual sampling site, the maximum standardized uptake value (SUV max ) of 68 Ga-DOTATATE was correlated with MR imaging findings, histology, and semiquantitative SSTR2 expression. Results: One hundred fifteen samples (81 tumor, 34 tumor-free) were obtained. There was a significant positive correlation between SUV max and SSTR2 expression. Receiver-operating characteristic analysis revealed a threshold of 2.3 for SUV max to discriminate between tumor and nontumoral tissue. Regarding the detection of tumor tissue, PET imaging showed a higher sensitivity (90% vs. 79%; P 5 0.049), with specificity and positive predictive values similar to MR imaging, for both de novo and recurrent tumors. Conclusion: 68 Ga-DOTATATE uptake correlates with SSTR2 expression and offers high diagnostic accuracy to delineate meningioma from tumor-free tissue even in recurrent tumors after previous therapy. Our findings substantiate an important role for 68 Ga-DOTATATE PET in meningioma management.

Objective: The aim of the current prospective study was to analyse the validity of MRI based diagnosis of brainstem gliomas which was verified by stereotactic biopsy and follow-up evaluation as well as to assess prognostic factors and risk profile. Methods: Between 1998 and 2007, all consecutive adult patients with radiologically suspected brainstem glioma were included. The MRI based diagnosis of the lesions was made independently by an experienced neuroradiologist. Histopathological evaluation was performed in all patients from paraffin embedded specimens obtained by multimodal image guided stereotactic serial biopsy technique. Histopathological results were compared with prior radiological assessment. Length of survival was estimated with the Kaplan-Meier method and prognostic factors were calculated using the Cox model.

Objective: Transsphenoidal surgery (TSS) presents the treatment of choice for Cushing's disease (CD). Remission and recurrence rates vary dependent on tumor size, extension, adenoma visibility on magnetic resonance imaging, and neurosurgical expertise. Other than published from single-surgeon neurosurgical series so far, we have aimed to describe long-term remission and recurrence rates of CD in a series incorporating different neurosurgeons, trying to reflect care reality in the Munich Metropolitan Region, which is accommodated by three tertiary university and multiple, smaller neurosurgical centers. Design: We conducted a retrospective analysis of 120 patients who underwent first and 36 patients who underwent second TSS as treatment for CD between 1990 and 2012. Methods: Patients were divided into three groups according to remission status. Potential risk factors for recurrence, pituitary function, and strategy in persistent disease were assessed. Results: Three outcome groups were identified according to remission status after first TSS (mean follow-up 79 months): remission, 71% (85/120), disease persistence, 29% (35/120), and disease recurrence, 34% (29/85) (mean time to recurrence 54 months). After second TSS (nZ36, mean follow-up 62 months), we documented remission in 42% (15/36), disease persistence in 58% (21/36), and disease recurrence in 40% (6/15) (mean time to recurrence 42 months). Postoperative hypocortisolism after first, though not after second, TSS was associated with a lower risk of suffering disease recurrence (riskZ0.72; 95% CI 0.60-0.88; exact significance (two-sided) PZ0.035). Conclusions: Our study shows higher recurrence rates of CD after first TSS than previously reported. Second TSS leads an additional 8% of the patients to long-term CD remission.

Recurrence appears to be more frequent and earlier after TSS in patients with USP8 mutant corticotroph tumours.

Abstract. Purpose: Intracavitary radioimmunotherapy (RIT) offers an effective adjuvant therapeutic approach in patients with malignant gliomas. Since differentiation between recurrence and reactive changes following RIT has a critical impact on patient management, the aim of this study was to analyse the value of serial O-(2-[ 188 Relabelled (n=5) anti-tenascin antibodies. Patients were monitored with serial FET PET scans (2-12 scans). For semiquantitative evaluation, maximal tumoural uptake (TU max ) was evaluated and the ratio to background (BG) was calculated. Results of PET were correlated with histopathological findings (n=9) and long-term clinical follow-up for up to 87 months. Results: In seven tumour-free patients, PET revealed slightly increasing but homogeneous FET uptake surrounding the resection cavity with a peak up to 18 months following RIT (TU max /BG 2.07±0.25) but stable or decreasing values during further follow-up (last followup: TU max /BG 1.63±0.22). Seventeen patients developed regrowth of residual tumour/tumour recurrence showing additional nodular FET uptake (TU max /BG 2.79±0.53). A threshold value of 2.4 (TU max /BG) allowed best differentiation between recurrence and reactive changes (sensitivity 82%, specificity 100%). Conclusion: FET PET is a sensitive tool for monitoring the effects of locoregional RIT. Homogeneous, slightly increasing FET uptake around the tumour cavity with a peak up to 18 months after RIT, followed by stable or decreasing uptake, points to benign, therapy-related changes. In contrast, nodular uptake is a reliable indicator of recurrence.

Various approaches to the anterior cranial fossa exist, each with corresponding advantages and disadvantages. Recently, endoscopic approaches have increasingly been used. In this review, the different approaches to meningiomas of the anterior cranial fossa in respect of anatomical issues, indications, and associated risks are discussed.