The purpose of the present study is to compare the characteristics, i.e. efficacy, duration, safety and hospital stay, of a frameless fiducial-less brain biopsy method with those of the standard frame-based stereotactic technique, in order to apply a technique friendlier to the patient, more comfortable for the surgeon and more flexible concerning the overall hospital's function.~Inclusion criteria: adult patients with cerebral lesions: 1) for whom no conclusive diagnosis could be settled in a noninvasive manner; and 2a) who also had surgically inaccessible lesions (or involving eloquent areas), or multifocal lesions, or lesions for which the probable diagnosis is a contraindication for craniotomy, or 2b) were too ill or too old for open craniotomy.~Type of Intervention: standard frame-based stereotactic brain biopsy technique or frameless fiducial-less method using an optical based navigation system and a mini frame apparatus - trajectory guide.~The following parameters will be assessed: diagnostic yield, histological - cytological evaluation of the biopsy specimens, cerebral lesions' location, lesions' maximum diameter, duration of: the overall procedure, the preparatory steps overall, the preparation inside the OR, operation (skin-to-skin), the time spent inside the OR overall, neurologic morbidity, new abnormal findings in the postoperative head CT scan, length of hospitalization.
The purpose of the present study is to compare the characteristics, i.e. efficacy, duration, safety and hospital stay, of a frameless fiducial-less brain biopsy method with those of the standard frame-based stereotactic technique.~Inclusion criteria: adult patients with cerebral lesions: 1) for whom no conclusive diagnosis could be settled in a noninvasive manner; and 2a) who also had surgically inaccessible lesions (or involving eloquent areas), or multifocal lesions, or lesions for which the probable diagnosis is a contraindication for craniotomy, or 2b) were too ill or too old for open craniotomy.~Type of Intervention: standard frame-based stereotactic brain biopsy technique or frameless fiducial-less method using an optical based navigation system and a mini frame apparatus - trajectory guide.