Monitoring Response to Therapy

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-18-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. (C) 2017 Elsevier Inc. All rights reserved

Impact of optimized PET imaging conditions on F-18-FDG uptake quantification in patients with apparently normal aortas

Background The cardiovascular committee of the European Association of Nuclear Medicine (EANM) recently published recommendations on imaging conditions to be observed during F-18-FDG PET imaging of vascular inflammation. This study aimed to evaluate the impact of applying these optimized imaging conditions on PET quantification of arterial F-18-FDG uptake. Methods and Results Fifty-seven patients were prospectively recruited to undergo an early F-18-FDG PET/CT imaging at 60 minutes and repeat delayed imaging at >= 120 minutes post tracer injection. Routine oncologic F-18-FDG PET protocol was observed for early imaging, while delayed imaging parameters were optimized for vascular inflammation imaging as recommended by the EANM. Aortic SUVmax of the ascending aorta and SUVmean from the lumen of the superior vena cava (SVC SUVmean) were obtained on early and delayed imaging. Target-to-background ratio (TBR) was obtained for the early and delayed imaging. Aortic SUVmax increased by a mean of 70%, while SVC SUVmean decreased by a mean of 52% between early and delayed imaging (P 180 minutes. Aortic SUVmax significantly increased at imaging time-points between 120 and 180 minutes. No significant improvement in aortic SUVmax was seen at imaging time-points beyond 180 minutes. Conclusions F-18-FDG PET imaging conditions optimized for vascular inflammation imaging lead to an improved quantification through an increase in the quantified vascular tracer uptake and decrease in blood-pool background activity

Underutilisation of nuclear medicine scans at a regional hospital in Nigeria : need for implementation research

BACKGROUND: Nuclear medicine needs better integration into the Nigerian health system. To understand the relevant public health initiatives that will be required, this study assessed the pattern of nuclear medicine imaging services at the first nuclear medicine centre in Nigeria from January 2010 to December 2018. METHODS: The data of consecutive nuclear medicine (NM) scans performed between 1st January 2010 and 31st December 2018 at the NM department in a tertiary hospital in Nigeria were extracted from patient records and analysed using SAS version 9.4 (SAS Institute, Cary, NC). The National Cancer Institute’s Joinpoint software and QCIS (QGIS project) were used to estimate imaging trends and geographical spread of patients. RESULTS: An average of 486 scans per year was performed during the study period. Patients travelled from 32 of Nigeria’s 36 states, and the majority (65%) travelled more than 100 km to obtain NM scans. Bone scans accounted for 88.1% of the studies. The remainder were renal scintigraphy (7.3%), thyroid scans (2.5%), whole-body iodine scans (1.7%) and others (0.4%). CONCLUSIONS: NM in Nigeria appears underutilised. Furthermore, the studies to characterise the access gaps and implementation needs will contribute to the design of practical strategies to strengthen NM services in Nigeria.https://ecancer.org/en/journalpm2020Nuclear Medicin

Radionuclide Imaging of Invasive Fungal Disease in Immunocompromised Hosts

Invasive fungal disease (IFD) leads to increased mortality, morbidity, and costs of treatment in patients with immunosuppressive conditions. The definitive diagnosis of IFD relies on the isolation of the causative fungal agents through microscopy, culture, or nucleic acid testing in tissue samples obtained from the sites of the disease. Biopsy is not always feasible or safe to be undertaken in immunocompromised hosts at risk of IFD. Noninvasive diagnostic techniques are, therefore, needed for the diagnosis and treatment response assessment of IFD. The available techniques that identify fungal-specific antigens in biological samples for diagnosing IFD have variable sensitivity and specificity. They also have limited utility in response assessment. Imaging has, therefore, been applied for the noninvasive detection of IFD. Morphologic imaging with computed tomography (CT) and magnetic resonance imaging (MRI) is the most applied technique. These techniques are neither sufficiently sensitive nor specific for the early diagnosis of IFD. Morphologic changes evaluated by CT and MRI occur later in the disease course and during recovery after successful treatment. These modalities may, therefore, not be ideal for early diagnosis and early response to therapy determination. Radionuclide imaging allows for targeting the host response to pathogenic fungi or specific structures of the pathogen itself. This makes radionuclide imaging techniques suitable for the early diagnosis and treatment response assessment of IFD. In this review, we aimed to discuss the interplay of host immunity, immunosuppression, and the occurrence of IFD. We also discuss the currently available radionuclide probes that have been evaluated in preclinical and clinical studies for their ability to detect IFD.</p

FDG PET/CT for evaluating systemic arterial inflammation induced by anthracycline-based chemotherapy of Hodgkin lymphoma : a retrospective cohort study

To evaluate arterial fluorodeoxyglucose (FDG) uptake as a marker of arterial inflammation in multiple vascular beds in patients treated with anthracycline-based chemotherapy for Hodgkin lymphoma (HL). We used maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR) to quantify arterial FDG uptake in the carotid artery, ascending aorta, abdominal aorta, and femoral artery obtained on positron emission tomography/computed tomography (PET/CT) imaging performed at baseline before chemotherapy and after completion of chemotherapy in patients with HL treated with an anthracycline-containing regimen. We compared the SUVmax and TBR obtained at baseline with that obtained postchemotherapy for each arterial bed to evaluate the effect of anthracycline-based chemotherapy. We evaluated the effect of cardiovascular risk factors such as human immunodeficiency virus (HIV) infection, smoking, hypertension, and diabetes on the changes in SUVmax and TBR seen in the different arterial beds after anthracycline-based chemotherapy. Fifty-two patients were included with a mean age of 34.56±10.19 years. There were 33 males, and 18 patients were HIV-infected. The mean interval between completion of chemotherapy and follow-up flourine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan was 65 weeks. We found no significant difference in arterial FDG uptake measured by SUVmax and TBR in all arterial beds between the pre- and post-chemotherapy FDG PET/CT. There was no significant impact of HIV infection, smoking, and hypertension on the changes in arterial FDG uptake following treatment with anthracyclinebased chemotherapy. In patients with HL who were treated with anthracycline-based chemotherapy, we found no significant increase in arterial inflammation measured by FDG PET/CT after an average follow-up period of about 65 weeks since completion of chemotherapy.https://journals.lww.com/md-journal/pages/default.aspxam2021Nuclear Medicin

[68Ga]Ga-NODAGAZOL uptake in atherosclerotic plaques correlates with the cardiovascular risk profile of patients

Please read abstract in the article.http://link.springer.com/journal/12149hj2023CardiologyNuclear Medicin

Correlation between CT features of active tuberculosis and residual metabolic activity on end-of-treatment FDG PET/CT in patients treated for pulmonary tuberculosis

Patients who complete a standard course of anti-tuberculous treatment (ATT) for pulmonary tuberculosis and are declared cured according to the current standard of care commonly have residual metabolic activity (RMA) in their lungs on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PER/CT) imaging. RMA seen in this setting has been shown to be associated with relapse of tuberculosis. The routine clinical use of FDG PET/CT imaging for treatment response assessment in tuberculosis is hindered by cost and availability. CT is a more readily available imaging modality. We sought to determine the association between CT features suggestive of active tuberculosis and RMA on FDG PET/CT obtained in patients who completed a standard course of ATT for pulmonary tuberculosis. We prospectively recruited patients who completed a standard course of ATT and declared cured based on negative sputum culture. All patients had FDG PET/CT within 2 weeks of completing ATT. We determined the presence of RMA on FDG PET images. Among the various lung changes seen on CT, we considered the presence of lung nodule, consolidation, micronodules in tree-in-bud pattern, FDG-avid chest nodes, and pleural effusion as suggestive of active tuberculosis. We determine the association between the presence of RMA on FDG PET and the CT features of active tuberculosis. We include 75 patients with a mean age of 36.09 ± 10.49 years. Forty-one patients (54.67%) had RMA on their FDG PET/CT while 34 patients (45.33%) achieved complete metabolic response to ATT. There was a significant association between four of the five CT features of active disease, p < 0.05 in all cases. Pleural effusion (seen in two patients) was the only CT feature of active disease without a significant association with the presence of RMA. This suggests that CT may be used in lieu of FDG PET/CT for treatment response assessment of pulmonary tuberculosis.CRDF Global for the project titled: The Clinical Research Unit (CRU) for the Advancement of Tuberculosis (TB) Biomarker-Targeted Interventions.http://frontiersin.org/Medicinedm2022Medical MicrobiologyNuclear Medicin

[68ga]ga-pentixafor for pet imaging of vascular expression of cxcr-4 as a marker of arterial inflammation in hiv-infected patients : a comparison with18f[fdg] pet imaging

People living with human immunodeficiency virus (PLHIV) have excess risk of atherosclerotic cardiovascular disease (ASCVD). Arterial inflammation is the hallmark of atherogenesis and its complications. In this study we aimed to perform a head-to-head comparison of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) and Gallium-68 pentixafor positron emission tomography/computed tomography [68Ga]Ga-pentixafor PET/CT for quantification of arterial inflammation in PLHIV. We prospectively recruited human immunodeficiency virus (HIV)-infected patients to undergo [18F]FDG PET/CT and [68Ga]Ga-pentixafor PET/CT within two weeks of each other. We quantified the levels of arterial tracer uptake on both scans using maximum standardized uptake value (SUVmax) and target–background ratio. We used Bland and Altman plots to measure the level of agreement between tracer quantification parameters obtained on both scans. A total of 12 patients were included with a mean age of 44.67 ± 7.62 years. The mean duration of HIV infection and mean CD+ T-cell count of the study population were 71.08 ± 37 months and 522.17 ± 260.33 cells/µL, respectively. We found a high level of agreement in the quantification variables obtained using [18F]FDG PET and [68Ga]Ga-pentixafor PET. There is a good level of agreement in the arterial tracer quantification variables obtained using [18F]FDG PET/CT and [68Ga]Ga-pentixafor PET/CT in PLHIV. This suggests that [68Ga]Ga-pentixafor may be applied in the place of [18F]FDG PET/CT for the quantification of arterial inflammation.http://www.mdpi.com/journal/biomoleculespm2021Nuclear Medicin

A prospective investigation of tumor hypoxia imaging with 68Ga-nitroimidazole PET/CT in patients with carcinoma of the cervix uteri and comparison with 18F-FDG PET/CT : correlation with immunohistochemistry

Hypoxia in cervical cancer has been associated with a poor prognosis. Over the years 68Ga labelled nitroimidazoles have been studied and have shown improved kinetics. We present our initial experience of hypoxia Positron Emission Tomography (PET) imaging in cervical cancer with 68Ga-Nitroimidazole derivative and the correlation with 18F-FDG PET/CT and immunohistochemistry. Twenty women with cervical cancer underwent both 18F-FDG and 68Ga-Nitroimidazole PET/CT imaging. Dual-point imaging was performed for 68Ga-Nitroimidazole PET. Immunohistochemical analysis was performed with hypoxia inducible factor-1 (HIF-1 ). We documented SUVmax, SUVmean of the primary lesions as well as tumor to muscle ratio (TMR), tumor to blood (TBR), metabolic tumor volume (MTV) and hypoxic tumor volume (HTV). There was no significant difference in the uptake of 68Ga-Nitroimidazole between early and delayed imaging. Twelve patients had uptake on 68Ga-Nitroimidazole PET. Ten patients demonstrated varying intensities of HIF-1 expression and six of these also had uptake on 68Ga-Nitroimidazole PET. We found a strong negative correlation between HTV and immunohistochemical staining (r = 0.660; p = 0.019). There was no correlation between uptake on PET imaging and immunohistochemical analysis with HIF-1 . Two-thirds of the patients demonstrated hypoxia on 68Ga-Nitroimidazole PET imaging.https://www.mdpi.com/journal/jcmam2022Nuclear Medicin