PET/CT: Dementia and Infection/Inflammation (2025)-T1-CNMMI09-2025

Video Transcription

Video Summary

The transcript summarizes two RSNA PET/CT talks: one on dementia—focused on Alzheimer’s disease (AD)—and one on infection/inflammation imaging with FDG.<br /><br />Cristina, a nuclear medicine physician, explains why cerebral blood flow and glucose metabolism reflect brain function and stresses controlling patient stimulation during FDG uptake to ensure “resting-state” brain metabolism. She distinguishes normal aging (mild frontal hypometabolism and cortical atrophy) from dementia. AD is defined pathologically by amyloid plaques and tau neurofibrillary tangles; PET tracers exist for both (three FDA-approved amyloid tracers; tau PET available but still improving for intermediate/early tau). She reviews evolving diagnostic frameworks (2011 guidelines and the 2016 ATN system: Amyloid/Tau/Neurodegeneration), updated appropriate-use criteria (2024/2025) including plasma biomarkers and emphasis on symptomatic patients. She notes open questions about choosing PET versus CSF/blood biomarkers, combining amyloid and tau PET, and the need for quantification—illustrated by reduced amyloid burden after lecanemab.<br /><br />The second speaker reviews FDG fundamentals and preparation, emphasizing that uptake is not cancer-specific and that insulin, activity, and diet can alter biodistribution; special prep can suppress myocardial uptake for cardiac infection/inflammation. Case-based examples show common mimics (epiploic appendagitis, talc pleurodesis, radiation pneumonitis, myositis ossificans, elastofibroma dorsi), and highlight FDG PET’s value in fever of unknown origin (infected cysts, endocarditis with splenic abscess, disseminated fungal infection identified via biopsy guidance). Immune-therapy toxicities (autoimmune pancreatitis, hypophysitis) are also demonstrated.

Keywords

Alzheimer’s disease PET imaging

FDG brain PET resting-state protocol

Amyloid PET tracers FDA-approved

Tau PET and ATN framework

Lecanemab amyloid burden quantification

FDG PET/CT infection and inflammation

Fever of unknown origin FDG PET

FDG PET mimics and immune-therapy toxicities