Expert opinions in nuclear medicine: Finding the “holy grail” in infection imaging

Abstract

Nuclear medicine imaging techniques are now widely accepted and increasingly used for diagnosing and treatment monitoring of infectious and inflammatory diseases. The latter has been exemplified by numerous recent clinical guidelines in which PET imaging is now part of the diagnostic flowcharts. In this perspective paper we discuss the current available guidelines, the current limitations, and we provide the future aims of research to achieve the holy grail in nuclear medicine: the differentiation between infection, inflammation and malignancy.

Insights into Peptidoglycan-Targeting Radiotracers for Imaging Bacterial Infections: Updates, Challenges, and Future Perspectives

“…10−12 The most recently added imaging modality is the advanced ultrafast large axial field of view (LAFOV)PET/CT, guaranteed to provide high sensitivity at low radiation doses. 13 These nuclear medicine imaging techniques rely on diagnostic radiotracers, with the most commonly used infection imaging agents being radiolabeled white blood cells, [ 67/68 Ga]citrate, [ 111 In]oxine/[ 99m Tc]hexamethylpropyleneamine oxime (HMPAO), and 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG). However, despite their wide application in infection imaging, these radiotracers have limitations in differentiating infection from inflammation, which can lead to ambiguity in diagnosis.…”

“…However, these imaging techniques primarily detect anatomical abnormalities and may not always reveal the presence of an infection. , Moreover, when it comes to early detection of infection, morphologic imaging using ultrasound (US), CT, and MRI are not well-suited, as these modalities primarily identify tissue architectural distortion that often occurs at an advanced stage of infection . To address the limitations mentioned above, nuclear medicine imaging scans such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have been considered promising alternatives, because they can assess early infection-related physiological abnormalities. , In hybrid imaging of infection, SPECT and PET are combined with the morphological information afforded by the anatomic imaging with CT or MRI for improved specificity. − The most recently added imaging modality is the advanced ultrafast large axial field of view (LAFOV)­PET/CT, guaranteed to provide high sensitivity at low radiation doses …”

“… 10 − 12 The most recently added imaging modality is the advanced ultrafast large axial field of view (LAFOV)PET/CT, guaranteed to provide high sensitivity at low radiation doses. 13 …”

Recently developed radiopharmaceuticals for bacterial infection imaging

“…The prediction is that the major cause of death, globally by 2050, will be drug-resistant infections (Akter et al 2023 ; Mota et al 2020a ; Kleynhans et al 2023 ; Signore et al 2023 ; Jain 2022 ; Fang et al 2020 ). With the major threat posed by antimicrobial resistance to the healthcare system and the effective treatment of infections, fast and accurate diagnosis of infections, and the reliable identification of intractable and resistant infection, are becoming more crucial for the application of antibiotic stewardship and to avoid overuse of broad-spectrum antibiotics (Akter et al 2023 ; Mota et al 2020a ; Fang et al 2020 ; Glaudemans and Gheysens 2023 ; Gouws et al 2022 ; Pijl et al 2021 ; Welling et al 2019 ).…”

“…Anatomical radiographic imaging lacks initial sensitivity to detect infection and has no specificity to differentiate between various infectious diseases, as morphologic changes often occur in the later stages of infection (Akter et al 2023 ; Jasińska et al 2022 ; Giraudo et al 2020 ; Mota et al 2020a ; Palestro 2019 ; Signore et al 2023 ; Pijl et al 2021 ; Seltzer et al 2019 ). However, molecular imaging with the use of nuclear medicine reflects pathophysiological processes and changes, allowing early detection and localisation of infection and inflammatory processes, as well as accurate monitoring of treatment response (Holcman et al 2023 ; Jasińska et al 2022 ; Albano et al 2020 ; Giraudo et al 2020 ; Palestro 2019 , 2020 ; Meyer et al 2019 ; Kleynhans et al 2023 ; Signore et al 2023 ; Glaudemans and Gheysens 2023 ; Pijl et al 2021 ; Seltzer et al 2019 ). Since the discovery of gallium-67 for medical use in the 1940s (Dittrich and Jesus 2022 ) and, later on, autologous leukocytes radiolabelled with indium-111, reported for the first time in 1976 (Segal et al 1976 ), and technetium-99m, a few years later, for infection imaging, there has been a continuous search for more bacteria-specific radiopharmaceuticals to be utilised for infection imaging (Akter et al 2023 ; Palestro 2019 ; Glaudemans and Gheysens 2023 ; Gouws et al 2022 ; Pijl et al 2021 ; Dadachova and Rangel 2022 ; Signore et al 2022 ; Koźmiński et al 2021 ).…”