Background:T2-hyperintense foci are one of the most frequent findings in cerebral magnetic resonance imaging (MRI). They can pose serious diagnostic problems which is reflected by their English name and abbreviation – UBOs (Unidentified Bright Objects).Material/Methods: Cerebral MRI results of 246 patients (134 females, 112 males), aged 2 –79 years, were analyzed. The examinations were done with the 0.5 and 1.5 T MRI scanners. T1-, PD or FLAIR and T2-weighted images were obtained. Diffusion-weighted imaging (DWI) was also performed in a high field system.Results: The following diagnoses were established: widened perivascular spaces in 11 cases, foci most probably associated with brain aging –21, with migraine –15, ischaemic changes –52, vasculitis –12, hypoxic-ischaemic changes –8, haemorrhagic foci –11, inflammatory changes –20, multiple sclerosis –50, central pontine and extrapontine myelinolysis –7, metastases –7, changes caused by radio-and chemotherapy – 8, lesions associated with neurometabolic diseases – 10, CNS degenerative diseases – 13, eclampsia – 1.Conclusions: MRI is a sensitive method of CNS focal lesions detection but is less specific as far as their differentiation is concerned. Particular features of the focal lesions on MR images (number, size, location, presence or lack of edema, reaction to contrast medium, evolution in time), as well as accompanying features (atrophy of particular brain structures, postcontrast enhancement of leptomeninges, coexistence of diffuse lesions, coexistence of spinal lesions) are the significant differentiating elements. However, they can not be considered in isolation from clinical data and other diagnostic tests results.

Keywords: T2--hyperintensities, MRI