**3. Results**

A group of 15 patients (9 females and 6 males) were eligible for the study. The median age was 70 years (range: 32–88 years). All patients underwent anatomical neuroimaging of the brain—in 5 cases, head CT and in the remaining cases, MRI. A total of 14 patients also underwent lumbar puncture; in one patient, due to lack of consent, only blood tests were performed. The whole group was evaluated for the presence of onconeuronal antibodies [Table 5]. Positive results of [18F]FDG PET/CT were found in 8 out 15 cases, which were associated with 4 types of neurological PNS.

The following percentages of positive results were found: in patients with myelitis 100% (1 case), cerebral degeneration 75% (3 of 4 cases) and among patients with polyneuropathies 50% (2 of 4 cases).

Among patients with myasthenia gravis, primary angiitis of the central nervous system and motor neuron disease there were no positive results of PET/CT (total number of observations: 4). The increased FDG uptake was found in 4 cases in lungs, in 1 case in colon, in 2 cases in lymph nodes of neck and chest and in 1 case in stomach (Figure 1).

**Figure 1.** MRI and PET/CT results of a patient with cerebellar degeneration. (**A**,**B**) nonspecific vascular demyelination detected on MRI. (**C**,**D**) metabolically active area in the pylorus and in the locoregional lymph nodes detected on [18F]FDG PET/CT.


#### **Table 5.** Clinical. biochemical. and imaging data of patients included in the study.

The mean value of SUV max in pathological findings were 6.59 (range 2.2–10.5).

The [18F]FDG PET/CT findings along with patients' demographic information, clinical presentation, results of brain/spinal cord imaging, presence and type of onconeural antibodies, and CSF analysis results are summarized in Table 5.
