This chapter explores recent advances in neuroimaging techniques for detecting and monitoring Long COVID fatigue, highlighting the emergence of novel biomarkers across multiple imaging modalities. The text examines significant findings from magnetic resonance imaging studies showing white matter microstructural changes in COVID-19 patients, even in cases of mild infection, and discusses the promising development of multimodal integration biomarkers. Through detailed analysis of both MRI and PET imaging findings, the chapter demonstrates how these complementary approaches reveal critical insights into metabolic and inflammatory changes associated with Long COVID. Special attention is given to the role of artificial intelligence and dimension reduction techniques in multimodal neuroimaging analysis, with recent research showing dramatic improvements in detection sensitivity when combining PET and MRI data. The chapter concludes with a comparative analysis of different neuroimaging modalities, discussing their relative strengths and practical implementation considerations. Throughout, the text emphasizes both the potential and limitations of these advanced imaging techniques, highlighting the need for standardized protocols and validation studies while acknowledging the challenges of implementing these methods in clinical settings. This comprehensive review provides crucial insights into how neuroimaging advances are enhancing our understanding of Long COVID fatigue’s underlying mechanisms and potential therapeutic approaches.