Brain perfusion scintigraphy with [99mTc]Tc-HMPAO in patients with autoimmune diseases

Diagnosing central nervous system (CNS) involvement in patients with autoimmune diseases remains a significant clinical challenge. Magnetic resonance imaging (MRI) often fails to reveal abnormalities in patients presenting with CNS-related symptoms. Despite the increasing interest in brain perfusion imaging in autoimmune diseases, studies assessing the utility of scintigraphy in this context remain limited. A review of the existing literature indicates a lack of comparative studies evaluating scintigraphy, MRI, and clinical symptoms in the early diagnosis and monitoring of CNS involvement in rheumatic diseases. This study aimed to assess the utility of brain single photon emission computed tomography (SPECT) scintigraphy with hexamethylpropyleneamine oxime labeled with technetium-99m ([99mTc]Tc-HMPAO) and MRI in visualizing cerebral perfusion disturbances in patients with rheumatic diseases presenting CNS-related symptoms.

A total of 204 brain perfusion SPECT scintigraphies using [99mTc]Tc-HMPAO from 71 patients (10 men and 61 women, aged 20-69 years) were retrospectively analyzed. The study included patients presenting with clinical symptoms such as severe headaches, memory impairment, and cognitive dysfunction who were diagnosed with systemic lupus erythematosus (n = 52), antiphospholipid syndrome (n = 9), Sjögren's syndrome (n = 5), and undifferentiated connective tissue disease (n = 5). Analysis was done in patients who underwent a minimum of two brain scintigraphies at intervals of at least six months (mean interval: 1 year ± 2 months). Due to the absence of a universally accepted diagnostic gold standard, initial SPECT scans were compared with follow-up images and current clinical symptoms by two independent physicians. Image analysis was conducted using dedicated software for the processing and interpretation of brain SPECT perfusion studies. In 65 patients, a brain MRI scan had been performed and compared to the brain scintigraphy results.

In 24 patients, regression of the disease in the brain perfusion scintigraphy was observed, while 31 patients showed progression of scintigraphic changes. In 16 patients, no differences were detected compared to the initial imaging. In 24/65 patients, brain MRI did not reveal any abnormalities, while in the scintigraphy, perfusion defects were visible. In 6 patients, no changes were seen in either brain MRI or scintigraphy. The analysis of results using Cohen's Kappa demonstrated a good correlation: 0.78 between cerebral perfusion scintigraphic changes observed in [99mTc]Tc-HMPAO SPECT and the clinical symptoms of patients.

Brain perfusion scintigraphy using [99mTc]Tc-HMPAO shows better correlation than brain MRI with the CNS clinical symptoms of patients with rheumatic diseases. This method appears to be a useful diagnostic tool for evaluating CNS involvement in patients presenting with neurological symptoms and normal findings on MRI.