Monitoring Response to Therapy

Abstract

Monitoring response to treatment is a key element in the management of infectious diseases, yet controversies still persist on reliable biomarkers for noninvasive response evaluation. Considering the limitations of invasiveness of most diagnostic procedures and the issue of expression heterogeneity of pathology, molecular imaging is better able to assay in vivo biologic processes noninvasively and quantitatively. The usefulness of F-FDG-PET/CT in assessing treatment response in infectious diseases is more promising than for conventional imaging. However, there are currently no clinical criteria or recommended imaging modalities to objectively evaluate the effectiveness of antimicrobial treatment. Therapeutic effectiveness is currently gauged by the patient's subjective clinical response. In this review, we present the current studies for monitoring treatment response, with a focus on Mycobacterium tuberculosis, as it remains a major worldwide cause of morbidity and mortality. The role of molecular imaging in monitoring other infections including spondylodiscitis, infected prosthetic vascular grafts, invasive fungal infections, and a parasitic disease is highlighted. The role of functional imaging in monitoring lipodystrophy associated with highly active antiretroviral therapy for human immunodeficiency virus is considered. We also discuss the key challenges and emerging data in optimizing noninvasive response evaluation.

A semi-automatic technique to quantify complex tuberculous lung lesions on 18F-fluorodeoxyglucose positron emission tomography/computerised tomography images

“…The shortcomings of sputum culture to accurately indicate when TB treatment has achieved sterilising cure [ 24 – 26 ] escalate the cost to develop improved TB treatment options. This has led to a growing interest to use PET-CT imaging to monitor TB treatment response [ 27 – 29 ]. In animal models, FDG PET-CT has been used to accurately describe disease progression and response to treatment in pulmonary tuberculosis (PTB) [ 30 – 35 ].…”

Diagnostic Performance of 18F-FDG PET/CT in Infectious and Inflammatory Diseases according to Published Meta-Analyses

“…The role of 18 F-FDG PET/CT for assessing treatment response in infectious or inflammatory diseases is also promising [78]. However, there are currently no recommended imaging modalities to objectively evaluate the effectiveness of treatment.…”

“…However, there are currently no recommended imaging modalities to objectively evaluate the effectiveness of treatment. Therapeutic effectiveness is currently gauged by the patient's subjective clinical response [78].…”

Labelled Chemical Probes for Demonstrating Direct Target Engagement in Living Systems

“…For example, 18 F-fluorodeoxyglucose ( 18 F-FDG), an 18 F-labelled glucose derivative, has been extensively used as a PET biomarker to assess the function of metabolic pathways and diagnose or study cancer [49] and neurodegenerative diseases [50,51]. These PET biomarker probes aim to study biological processes in abnormal disease states and also potential changes in response to a therapeutic [52][53][54]. Here, we focus on the strategy that…”