Segmentation of gliomas in 18F-fluorocholine PET/CT. A multiapproach study. / Segmentación de gliomas con PET/TC con 18F-fluorocolina. Estudio multiaproximación.

AIM: Our aim was two-fold, to study the interobserver agreement in tumour segmentation and to search for a reliable methodology to segment gliomas using 18F-fluorocholine PET/CT. METHODS: 25 patients with glioma, from a prospective and non-randomized study (Functional and Metabolic Glioma Analysis), were included.Interobserver variability in tumour segmentation was assessed using fixed thresholds. Different strategies were used to segment the tumours. First, a semi-automatic tumour segmentation was performed, selecting the best SUVmax-% threshold for each lesion. Next we determined a variable SUVmax-% depending on the SUVmax. Finally a segmentation using a fixed SUVmax threshold was performed. To do so, a sampling of 10 regions of interest (ROI of 2.8cm2) located in the normal brain was performed. The upper value of the sample mean SUVmax±3 SD was used as cut-off. All procedures were tested and classified as effective or not for tumour segmentation by two observer's consensus. RESULTS: In the pilot segmentation, the mean±SD of SUVmax, SUVmean and optimal SUVmax-% threshold were: 3.64±1.77, 1.32±0.57 and 21.32±8.39, respectively. Optimal SUVmax-% threshold showed a significant association with the SUVmax (Pearson=-0.653, p=.002). However, the linear regression model for the total sample was not good, that supported the division in two homogeneous groups, defining two formulas for predicting the optimal SUVmax-% threshold. As to the third procedure, the obtained value for the mean SUVmax background+3 SD was 0.33. This value allowed segmenting correctly a significant fraction of tumours, although not all. CONCLUSION: A great interobserver variability in the tumour segmentation was found. None of the methods was able to segment correctly all the gliomas, probably explained by the wide tumour heterogeneity on 18F-fluorocholine PET/CT.

Cerebral solitary Langerhans cell histiocytosis: report of two cases and review of the literature.

Cerebral solitary Langerhans cell histiocytosis (LCH) is a very uncommon condition. We describe two new cases: a 30-year-old man with seizures and a tumour in the left frontal lobe, which was composed of a polymorphic infiltrate with a predominance of histiocytes and eosinophils; and a 65-year-old man with headaches and dysarthria, with a left parietal tumour, which showed a diffuse proliferation of histiocytic cells and areas of necrosis. In both cases, the histiocytes were strongly positive for S-100 and CD1a, and Birbeck's granules were demonstrated by electron microscopy in the first case. Both patients underwent a complete excision of their lesions. The second patient received additional postoperative radiotherapy. They were asymptomatic after 26 and 27 months, respectively. It seems that cerebral solitary LCH is a clinicopathological entity with a good outcome. Only 15 cases of this rare process have been previously reported in the English literature.

[Neurosurgical treatment of acoustic neuromas without indication for radiosurgery]. / Tratamiento neuroquirùrgico de los neurinomas del acùstico sin indicación de tratamiento con radiocirugía

The aim of this paper is to review the specific problems of the microsurgical management of the acoustic neuromas not suitable for radiosurgical treatment , that is measuring more than 8 cc in volume or 2.5 cm in maximum diameter in the cerebelopontine angle. A total of 18 lesions have been included with a mean volume of 27.4 cc, representing a lesion measuring 3.8 cm in its three main diameters. The mean follow-up has been 48.7 months. There has been no mortality. All lesions were completely excised without recurrences. The anatomic conservation of the facial nerve was achieved in the 66.7% of the cases but the functional recovery (House-Brackmann grades I-II) was reached only in the 27.8%, without any grade I case. As permanent deficit all patients had postoperative cophosis, two had trigeminal hyposthesia with corneal anesthesia and one had a cerebellar deficit. The main conclussion is that the microsurgical radical resection of large acoustic neuromas not suitable for radiosurgical treatment is followed by a high postoperative morbidity mainly related with the facial nerve lesion. Therefore, it seems rationale to design specific strategies directed to reduce and alleviate these permanent deficits.

Tratamiento neuroquirúrgico de los neurinomas del acústico sin indicación de tratamiento con radiocirugía / Neurosurgical treatmentof acoustic neuromas without indication for radiosurgery

El propósito de este trabajo es revisar la problemática de los neurinomas del acústico mayores de 8cc de volumen o 2,5cm de diámetro máximo en el ángulo pontocerebeloso, que no son susceptibles de tratamiento con radiocirugía. Se han incluido un total de 18 lesiones, con un volumen medio de 27.4cc, lo que equivale a una lesión de unos 3,8cm en sus tres diámetros. El seguimiento medio es de 48.7 meses. No hubo mortalidad. En todos los casos se consiguió la exéresis completa de la lesión sin recidivas, con conservación anatómica del nervio facial en el 66.7 por ciento de los casos y recuperación funcional (grados I-II de House-Brackmann) en el 27.8 por ciento, ninguno con grado I. Como secuelas definitivas, en todos los pacientes hubo cofosis, en dos casos hipostesia trigeminal con anestesia corneal y en un caso afectación cerebelosa. Se concluye señalando que la morbilidad de la exéresis de los neurinomas del acústico de gran tamaño es muy alta, es especial la afectación del nervio facial, por lo que es necesario diseñar estrategias especialmente dirigidas a minimizarlas (AU)