The Role of Nuclear Medicine in the Staging and Management of Human Immune Deficiency Virus Infection and Associated Diseases

Abstract

Human immune deficiency virus (HIV) is a leading cause of death. It attacks the immune system, thereby rendering the infected host susceptible to many HIV-associated infections, malignancies and neurocognitive disorders. The altered immune system affects the way the human host responds to disease, resulting in atypical presentation of these disorders. This presents a diagnostic challenge and the clinician must use all diagnostic avenues available to diagnose and manage these conditions. The advent of highly active antiretroviral therapy (HAART) has markedly reduced the mortality associated with HIV infection but has also brought in its wake problems associated with adverse effects or drug interaction and may even modulate some of the HIV-associated disorders to the detriment of the infected human host. Nuclear medicine techniques allow non-invasive visualisation of tissues in the body. By using this principle, pathophysiology in the body can be targeted and the treatment of diseases can be monitored. Being a functional imaging modality, it is able to detect diseases at the molecular level, and thus it has increased our understanding of the immunological changes in the infected host at different stages of the HIV infection. It also detects pathological changes much earlier than conventional imaging based on anatomical changes. This is important in the immunocompromised host as in some of the associated disorders a delay in diagnosis may have dire consequences. Nuclear medicine has played a huge role in the management of many HIV-associated disorders in the past and continues to help in the diagnosis, prognosis, staging, monitoring and assessing the response to treatment of many HIV-associated disorders. As our understanding of the molecular basis of disease increases nuclear medicine is poised to play an even greater role. In this review we highlight the functional basis of the clinicopathological correlation of HIV from a metabolic view and discuss how the use of nuclear medicine techniques, with particular emphasis of F-18 fluorodeoxyglucose, may have impact in the setting of HIV. We also provide an overview of the role of nuclear medicine techniques in the management of HIV-associated disorders.

Monitoring Response to Therapy

“…2,[71][72][73] Other reviews emphasize the response assessment as being the most important role of 18 F-FDG-PET/CT in TB image with the ability to assess disease activity over time with semiquantitative measures. 14,[74][75][76][77][78][79]…”

“…On 18 F-FDG-PET/CT, HIV-related lymphadenopathy may show metabolic uptake that may be difficult to distinguish from TB lymphadenitis. 78 These nodes very often may not be apparent on the baseline study but usually present on followup scans (Fig. 7).…”

Updates on 18F-FDG-PET/CT as a clinical tool for tuberculosis evaluation and therapeutic monitoring

“…Active TB lesions contain activated macrophages and lymphocytes, which have high levels of glucose utilization. 18 F-fluorodeoxyglucose ( 18 F-FDG) uptake reflects cell glycolysis and is found in activated macrophages and lymphocytes, both of which are prominent in TB and other granulomatous inflammatory processes, as well as in neoplastic cells. The rate of uptake is reported as a standardized uptake value (SUV), the regional radioactivity concentration divided by the total injected radiotracer dose and adjusted to the patient weight.…”

Neurocognitive dysfunction and brain FDG-PET/CT findings in HIV-infected hemophilia patients and HIV-infected non-hemophilia patients

“…temporal lobe metabolism and the severity of AIDS dementia [33], the decreasing pattern of FDG uptake in patients with HAND was considered nonspecific [4]. Of 56 hemophilia patients, 14 (25%) patients had history of cerebrovascular disorder.…”

“…According to reviews on neuroimaging studies of HAND, the prevalence of symptomatic HAND is associated with gray matter atrophy in brain magnetic resonance imaging (MRI) [3]. Although a 18-fluorine-fluorodeoxyglucose positron-emission-tomography/computed tomography ( 18 F-FDG-PET/CT) scan is not typically recommended for HAND diagnosis [4], FDG-PET has been widely used to investigate cognitive functions and patterns of cognitive alterations [5].…”