Neuro-oncological diagnosis in patients without histological confirmation.

The impossibility to conduct a histological diagnosis could be due to different reasons: (1) patient's refusal to undergo surgery/biopsy. (2) Technical difficulties: despite the advance in surgical procedures, the removal of lesions that are located either in critical or in deep areas represents a considerable risk for patients. (3) Quality/quantity of the sample. In rare cases even when the surgical sample is achieved it could be impossible to reach a histological confirmation, for example due to the small amount of tissue obtained. The lack of histology leads to suboptimal therapy, incorrect prognosis, and misinterpretation of clinical trials and furthermore undermines the possibility to perform most radiation and chemotherapy protocols. In this setting the morphological data obtained with conventional MR imaging may be integrated with the metabolic, structural and perfusional information provided by new MR and metabolic techniques (spectroscopy, SPECT, PET in particular).