Fluorodeoxyglucose uptake by lymph nodes of HIV patients is inversely related to CD4 cell count

EANM consensus document on the use of [18F]FDG PET/CT in fever and inflammation of unknown origin

PURPOSE

Patients with fever and inflammation of unknown origin (FUO/IUO) are clinically challenging due to variable clinical presentations with nonspecific symptoms and many differential diagnoses. Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is increasingly used in FUO and IUO, but the optimal diagnostic strategy remains controversial. This consensus document aims to assist clinicians and nuclear medicine specialists in the appropriate use of [18F]FDG-PET/CT in FUO and IUO based on current evidence.

METHODS

A working group created by the EANM infection and inflammation committee performed a systematic literature search based on PICOs with "patients with FUO/IUO" as population, "[18F]FDG-PET/CT" as intervention, and several outcomes including pre-scan characteristics, scan protocol, diagnostic yield, impact on management, prognosis, and cost-effectiveness.

RESULTS

We included 68 articles published from 2001 to 2023: 9 systematic reviews, 49 original papers on general adult populations, and 10 original papers on specific populations. All papers were analysed and included in the evidence-based recommendations.

CONCLUSION

FUO and IUO remains a clinical challenge and [18F]FDG PET/CT has a definite role in the diagnostic pathway with an overall diagnostic yield or helpfulness in 50-60% of patients. A positive scan is often contributory by directly guiding treatment or subsequent diagnostic procedure. However, a negative scan may be equally important by excluding focal disease and predicting a favorable prognosis. Similar results are obtained in specific populations such as ICU-patients, children and HIV-patients.

Clinical features and 18F-FDG PET/CT for distinguishing of malignant lymphoma from inflammatory lymphadenopathy in HIV-infected patients

Background

It is vital to distinguish between inflammatory and malignant lymphadenopathy in human immunodeficiency virus (HIV) infected individuals. The purpose of our study was to differentiate the variations in the clinical characteristics of HIV patients, and apply ¹⁸F-FDG PET/CT parameters for distinguishing of malignant lymphoma and inflammatory lymphadenopathy in such patients.

Methods

This retrospective cross-sectional study included 59 consecutive HIV-infected patients who underwent whole-body ¹⁸F-FDG PET/CT. Of these patients, 37 had biopsy-proven HIV-associated lymphoma, and 22 with HIV-associated inflammatory lymphadenopathy were used as controls. The determined parameters were the maximum of standard uptake value (SUV_max), SUV_max of only lymph nodes (SUV_LN), the most FDG-avid lesion-to-liver SUV_max ratio (SUR_max), laboratory examinations and demographics. The optimal cut-off of ¹⁸F-FDG PET/CT value was analyzed by receiver operating characteristic curve (ROC).

Results

Considering the clinical records, the Karnofsky Performance Status (KPS) scores in patients with inflammatory lymphadenopathy were obviously higher than those in patients with malignant lymphoma (P = 0.015), whereas lymphocyte counts and lactate dehydrogenase (LDH) were obviously lower (P = 0.014 and 0.010, respectively). For the ¹⁸F-FDG PET/CT imaging, extra-lymphatic lesions, especially digestive tract and Waldeyer’s ring, occurred more frequently in malignant lymphoma than inflammatory lymphadenopathy. Furthermore, the SUR_max and SUV_LN in malignant lymphoma were markedly higher than those in inflammatory lymphadenopathy (P = 0.000 and 0.000, respectively). The cut-off point of 3.1 for SUR_max had higher specificity (91.9%) and relatively reasonable sensitivity (68.2%) and the cut-off point of 8.0 for the SUV_LN had high specificity (89.2%) and relatively reasonable sensitivity (63.6%).

Conclusion

Our study identified the distinctive characteristics of the clinical manifestations, the SUR_max, SUV_LN and detectability of extra-lymphatic lesions on ¹⁸F-FDG PET, and thus provides a new basis for distinguishing of malignant lymphoma from inflammatory lymphadenopathy in HIV-infected patients.

18F-FDG-PET/CT imaging of uterine cervical cancer recurrence in women with and without HIV infection

BACKGROUND

To compare the rate, time and, pattern of recurrence of cervical cancer between patients with and without HIV infection and to determine factors predicting cervical cancer recurrence in patients evaluated by ¹⁸F-FDG-PET/CT.

METHODS

We reviewed the ¹⁸F-FDG-PET/CT images of patients with histologically proven cervical carcinoma who were presenting with suspected recurrence. We extracted epidemiologic data, previous treatment, histologic subtype, HIV status, viral load and CD4 counts from the electronic laboratory database and the referral form for the ¹⁸F-FDG-PET/CT study.

RESULTS

We studied 303 women including 112 HIV-infected patients. FIGO stage III disease was present in 131 patients. Of 198 patients with recurrence, 74 were HIV-infected while 124 were not (P=0.849). HIV infected patients were younger (41.99±9.30 years) compared to HIV-uninfected (50.19±11.09), P<0.001. Local recurrence was present in 125 patients while 100 patients had a distant recurrence. Recurrence occurred at a single site in 88 patients and two or more sites in 110 patients. No significant difference in the recurrent patterns between HIV-infected and uninfected patients. Median time to recurrence was 10.50 months (range: 6.00-156.00) among HIV-infected versus 12.00 months (IQR:7.00-312.00) among the uninfected, P=0.065. FIGO stage III (P=0.042) and the presence of histological sub-types other than SCC (P=0.005) were significant predictors of recurrence. HIV infection by itself was not significant in predicting recurrence (P=0.843).

CONCLUSIONS

HIV infection has no significant impact on the rate, time or pattern of recurrence in women with suspected cervical carcinoma recurrence. Advanced disease and histological variant other than SCC are predictive of recurrence.

Visualization of HIV-1 reservoir: an imaging perspective

PURPOSE OF REVIEW

The persistence of HIV-1-infected cells, despite the introduction of the combinatorial antiretroviral therapy, is a major obstacle to HIV-1 eradication. Understanding the nature of HIV reservoir will lead to novel therapeutic approaches for the functional cure or eradication of the virus. In this review, we will update the recent development in imaging applications toward HIV-1/simian immunodeficiency virus (SIV) viral reservoirs research and highlight some of their limitations.

RECENT FINDINGS

CD4 T cells are the primary target of HIV-1/SIV and the predominant site for productive and latent reservoirs. This viral reservoir preferentially resides in lymphoid compartments that are difficult to access, which renders sampling and measurements problematical and a hurdle for understanding HIV-1 pathogenicity. Novel noninvasive technologies are needed to circumvent this and urgently help to find a cure for HIV-1. Recent technological advancements have had a significant impact on the development of imaging methodologies allowing the visualization of relevant biomarkers with high resolution and analytical capacity. Such methodologies have provided insights into our understanding of cellular and molecular interactions in health and disease.

SUMMARY

Imaging of the HIV-1 reservoir can provide significant insights for the nature (cell types), spatial distribution, and the role of the tissue microenvironment for its in vivo dynamics and potentially lead to novel targets for the virus elimination.

18F-FDG PET/CT imaging of vulva cancer recurrence: A comparison of PET-derived metabolic parameters between women with and without HIV infection

Objective To assess the patterns of recurrence of vulva cancer on 18F-FDG PET/CT and to compare the 18F-FDG PET metabolic metrics in patients with and without Human Immunodeficiency Virus (HIV).

Methods Maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumour volume (MTV and total lesion glycolysis (TLG) were obtained on Flourine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F-FDG PET/CT) images of women referred with suspected or confirmed vulva cancer recurrence. We compared HIV-infected and HIV-uninfected patients regarding pattern disease recurrence, age at diagnosis, and the PET-derived metabolic indices.

Results We analyzed 33 patients with a mean age 50.76 ± 15.78 including 21 HIV-infected women. The majority of patients (94 %) had squamous cell carcinoma and 84.85 % were Blacks. Of the HIV-infected individuals, the median CD4 count was 526.0 cells/mm3 (IQR: 379.0–729.0). HIV infected patients were younger than the HIV uninfected at the time of diagnosis: 40.50 ± 8.87 vs 66.54 ± 9.71 respectively, p < 0.001. We found a local (vulvar) recurrence rate of 75.8 %. Nodal pelvic recurrences were higher in the HIV-infected patients than in the HIV uninfected patients (70 % vs 30 %, p = 0.027). Three patients had distant metastasis and all three were HIV-infected. There was a higher whole-body MTV and TLG among HIV-infected women compared with HIV-uninfected women, 103.39 vs 17.58 and 852.64 vs 101.79, respectively (p < 0.05 for both).

Conclusion HIV-infected women are diagnosed with vulva cancer at a younger age. HIV-infected patients had a higher rate of pelvic lymph node recurrence. There is a higher tumor burden at vulva cancer recurrence among women with HIV infection.

Defining Characteristics of Nodal Disease on PET/CT Scans in Patients With HIV-Positive and -Negative Locally Advanced Cervical Cancer in South Africa

Literature reports increased FDG nodal uptake in HIV-positive patients. Our aim is to identify differences in presentation and characteristics of FDG-avid lymph nodes between HIV-positive and HIV-negative locally advanced cervical cancer (LACC) patients in our clinical setting. We evaluated 250 pre-treatment ¹⁸F-FDG PET/CT imaging studies from women screened for a phase III randomised controlled trial investigating modulated electro-hyperthermia as a radiosensitiser (Ethics approval: M120477). The number of nodes; size; maximum standardised uptake value (SUVmax); symmetry; and relationship between nodal size and SUVmax uptake, were assessed by region and by HIV status. In total, 1314 nodes with a SUVmax ≥ 2.5 were visualised. Of 128(51%) HIV-positive participants, 82% were on antiretroviral therapy (ART) and 10 had a CD4 count <200 cells/µL. Overall pattern of presentation and nodal characteristics were similar between HIV-positive and -negative groups and the uniformity in presentation of the nodes draining the cervix strongly suggests these nodes may be attributed to malignancy rather than HIV infection. Novel findings: HIV infection is associated with: >four nodes visualised in the neck, symmetrical inguinal lymph nodes, increased rates of supraclavicular node visualisation; FDG-avid axillary nodes were more common, but not exclusive, in HIV-positive participants. ¹⁸F-FDG PET/CT is a reliable staging method for LACC in HIV-positive patients who are not in acute stages of HIV infection, have a CD4 count >200 cells/µL, and/or are on ART and there is a potential risk of underestimating metastatic spread by attributing increased nodal metabolic activity to HIV infection in these patients.

Potentiation of the Abscopal Effect by Modulated Electro-Hyperthermia in Locally Advanced Cervical Cancer Patients

Background: A Phase III randomized controlled trial investigating the addition of modulated electro-hyperthermia (mEHT) to chemoradiotherapy for locally advanced cervical cancer patients is being conducted in South Africa (Human Research Ethics Committee approval: M1704133; ClincialTrials.gov ID: NCT03332069). Two hundred and ten participants were randomized and 202 participants were eligible for six month local disease control evaluation. Screening ¹⁸F-FDG PET/CT scans were conducted and repeated at six months post-treatment. Significant improvement in local control was reported in the mEHT group and complete metabolic resolution (CMR) of extra-pelvic disease was noted in some participants. We report on an analysis of the participants with CMR of disease inside and outside the radiation field.

Method: Participants were included in this analysis if nodes outside the treatment field (FDG-uptake SUV>2.5) were visualized on pre-treatment scans and if participants were evaluated by ¹⁸F-FDG PET/CT scans at six months post-treatment.

Results: One hundred and eight participants (mEHT: HIV-positive n = 25, HIV-negative n = 29; Control Group: HIV-positive n = 26, HIV-negative n = 28) were eligible for analysis. There was a higher CMR of all disease inside and outside the radiation field in the mEHT Group: n = 13 [24.1%] than the control group: n = 3 [5.6%] (Chi squared, Fisher's exact: p = 0.013) with no significant difference in the extra-pelvic response to treatment between the HIV-positive and -negative participants of each group.

Conclusion: The CMR of disease outside the radiation field at six months post-treatment provides evidence of an abscopal effect which was significantly associated with the addition of mEHT to treatment protocols. This finding is important as the combined synergistic use of radiotherapy with mEHT could broaden the scope of radiotherapy to include systemic disease.

Metabolic plasticity of HIV-specific CD8+ T cells is associated with enhanced antiviral potential and natural control of HIV-1 infection

Spontaneous control of human immunodeficiency virus (HIV) is generally associated with an enhanced capacity of CD8⁺ T cells to eliminate infected CD4⁺ T cells, but the molecular characteristics of these highly functional CD8⁺ T cells are largely unknown. In the present study, using single-cell analysis, it was shown that HIV-specific, central memory CD8⁺ T cells from spontaneous HIV controllers (HICs) and antiretrovirally treated non-controllers have opposing transcriptomic profiles. Genes linked to effector functions and survival are upregulated in cells from HICs. In contrast, genes associated with activation, exhaustion and glycolysis are upregulated in cells from non-controllers. It was shown that HIV-specific CD8⁺ T cells from non-controllers are largely glucose dependent, whereas those from HICs have more diverse metabolic resources that enhance both their survival potential and their capacity to develop anti-HIV effector functions. The functional efficiency of the HIV-specific CD8⁺ T cell response in HICs is thus engraved in their memory population and related to their metabolic programme. Metabolic reprogramming in vitro through interleukin-15 treatment abrogated the glucose dependency and enhanced the antiviral potency of HIV-specific CD8⁺ T cells from non-controllers.

CT Texture Analysis of Cervical Lymph Nodes on Contrast-Enhanced [18F] FDG-PET/CT Images to Differentiate Nodal Metastases from Reactive Lymphadenopathy in HIV-Positive Patients with Head and Neck Squamous Cell Carcinoma

BACKGROUND AND PURPOSE

Differentiating nodal metastases from reactive adenopathy in HIV-infected patients with [¹⁸F] FDG-PET/CT can be challenging because lymph nodes in HIV-positive patients often show increased [¹⁸F] FDG uptake. The purpose of this study was to assess CT textural analysis characteristics of HIV-positive and HIV-negative lymph nodes on [¹⁸F] FDG-PET/CT to differentiate nodal metastases from disease-specific nodal reactivity.

MATERIALS AND METHODS

Nine HIV-positive patients with head and neck squamous cell carcinoma (7 men, 2 women; 29-62 years of age; median age, 48 years) with 22 lymph nodes (≥1 cm) who underwent contrast-enhanced CT with [¹⁸F] FDG-PET followed by pathologic evaluation of cervical lymph nodes were retrospectively reviewed. Twenty-six HIV-negative patients with head and neck squamous cell carcinoma with 61 lymph nodes were evaluated as a control group. Each lymph node was manually segmented, and an in-house-developed Matlab-based texture analysis program extracted 41 texture features from each segmented volume. A mixed linear regression model was used to compare the pathologically proved malignant lymph nodes with benign nodes in the 2 enrolled groups.

RESULTS

Thirteen (59%) lymph nodes in the HIV-positive group and 22 (36%) lymph nodes in the HIV-negative control group were confirmed as positive for metastases. There were 7 histogram features (P = .017-0.032), 3 gray-level co-occurrence features (P = .009-.025), and 9 gray-level run-length features (P < .001-.033) that demonstrated a significant difference in HIV-positive patients with either benign or malignant lymph nodes.

CONCLUSIONS

CT texture analysis may be useful as a noninvasive method of obtaining additional quantitative information to differentiate nodal metastases from disease-specific nodal reactivity in HIV-positive patients with head and neck squamous cell carcinoma.

Brain 18F-FDG PET of SIV-infected macaques after treatment interruption or initiation

BACKGROUND

Although rates of severe HIV-associated neurocognitive disorders have declined in the post-antiretroviral treatment (ART) era, subtle deficits persist, possibly exacerbated by treatment non-adherence. The actual effects of ART interruption/initiation on brain glucose metabolism as a reflection of viral replication and neuroinflammation remain unclear. Our study investigates how treatment initiation and interruption alter brain glucose metabolism in SIV-infected macaques, using 18F-FDG PET in correlation with plasma and CSF viral loads (VL) and cytokine levels.

METHODS

SIV-infected macaques (n = 7) underwent ART initiation only, ART interruption only, or both. Five uninfected animals served as controls. 18F-FDG PET imaging was performed at baseline and 1, 3, and 6 months after treatment modification. Mean and maximum standardized uptake values (SUV) for the whole-brain and subregions were calculated. Plasma and CSF VL and cytokine levels were measured. Paired t tests evaluated acute changes in whole-brain SUV from baseline to 1 month, while mixed-effect linear regression models evaluated changes over multiple timepoints and correlated SUV values with disease markers.

RESULTS

ART interruption was associated with increased SUVmean and SUVmax acutely, after 1 month (SUVmean 95% CI [0.044-0.786 g/ml], p = 0.037; SUVmax 95% CI [0.122-3.167 g/ml], p = 0.041). The correlation between SUV and time, however, was not significant when evaluated across all timepoints. Increased SUVmean and SUVmax correlated with decreased CD4+ and CD8+ T-cell counts and increased plasma VL. SUVmax was positively associated with increases in CSF VL, and there were borderline positive associations between SUVmax and IL-2, and between SUVmean and IL-15. The treatment initiation group showed no associations between imaging and disease biomarkers despite viral suppression, reduced cytokine levels, and increased CD4+ and CD8+ T-cell counts.

CONCLUSIONS

ART interruption is associated with increased brain glucose metabolism within 1 month of treatment cessation, which, in concert with increased levels of pro-inflammatory cytokines in the CSF, may reflect neuroinflammation in the setting of viral rebound. Although we cannot assert neurologic damage in association with cerebral hypermetabolism, it is a concerning outcome of ART non-adherence. Treatment initiation, meanwhile, did not result in significant changes in brain metabolism. HIV-induced neuroinflammation may require a longer period to abate than our follow-up period allowed.

Mycobacterium avium Complex Infection-Related Immune Reconstitution Inflammatory Syndrome Mimicking Lymphoma in an Human Immunodeficiency Virus-Infected Patient

In acquired immunodeficiency syndrome (AIDS) patients, immune reconstitution inflammatory syndrome (IRIS) due to Mycobacterium avium complex (MAC) infection is one of the most difficult IRIS types to manage. We report an unusual case of MAC-associated IRIS. At first the patient was diagnosed human immunodeficiency virus (HIV) infection after he was admitted with pneumocystis pneumonia. After starting antiretroviral therapy he presented unmasked IRIS with MAC infection. Next, he was hospitalized with continuous loose stools and new-onset fever. Investigation included computed tomography (CT), which showed homogeneous enhancement and enlargement of the lymph nodes (LN), elevation of ferritin (>1,650 ng/mL) and lactate dehydrogenase (306 IU/L) levels, and F- fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan, which showed increased FDG uptake. These findings were highly indicative of lymphoma. We performed laparoscopic biopsy of the mesenteric LN, and the biopsy culture grew MAC. So we made a diagnosis of MAC-associated. Therefore, IRIS must be considered as a possible diagnosis when AIDS patients develop new symptoms or exhibit exacerbations of existing symptoms. Furthermore the biopsies should be conducted.

PET/CT in nononcological lung diseases: current applications and future perspectives

Positron emission tomography (PET) combined with computed tomography (CT) is an established diagnostic modality that has become an essential imaging tool in oncological practice. However, thanks to its noninvasive nature and its capability to provide physiological information, the main applications of this technique have significantly expanded.(18)F-labelled fluorodeoxyglucose (FDG) is the most commonly used radiopharmaceutical for PET scanning and demonstrates metabolic activity in various tissues. Since activated inflammatory cells, like malignant cells, predominantly metabolise glucose as a source of energy and increase expression of glucose transporters when activated, FDG-PET/CT can be successfully used to detect and monitor a variety of lung diseases, such as infections and several inflammatory conditions.The added value of FDG-PET/CT as a molecular imaging technique relies on its capability to identify disease in very early stages, long before the appearance of structural changes detectable by conventional imaging. Furthermore, by detecting the active phase of infectious or inflammatory processes, disease progression and treatment efficacy can be monitored.This review will focus on the clinical use of FDG-PET/CT in nonmalignant pulmonary diseases.

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

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.

FDG PET/CT in infection and inflammation--current and emerging clinical applications

Integrated positron emission tomography/computed tomography (PET/CT) with the glucose analogue, 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG), is an evolving hybrid imaging technique in the evaluation of an important and diverse group of pathological conditions, which are characterised by infection and aseptic inflammation. With a rapidly expanding body of evidence, it is being increasingly recognised that, in addition to its established role in oncological imaging, FDG PET/CT also has clinical utility in suspected infection and inflammation. The technique can identify the source of infection or inflammation in a timely fashion ahead of morphological changes on conventional anatomical imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), map the extent and severity of disease, identify sites for tissue sampling, and assess therapy response. FDG PET/CT exhibits distinct advantages over traditional radionuclide imaging techniques in terms of shorter duration of examination, higher spatial resolution, non-invasive nature of acquisition, ability to perform quantitative analyses, and the provision of a synergistic combination of functional and anatomical imaging. With the use of illustrative clinico-radiological cases, this article discusses the current and emerging evidence for the use of FDG PET/CT in a broad spectrum of disorders, such as fever of unknown origin, sarcoidosis, large vessel vasculitis, musculoskeletal infections, joint prosthesis or implant-related complications, human immunodeficiency virus (HIV)-related infections, and miscellaneous indications, such as IgG4-related systemic disease. It will also briefly summarise the role of more novel tracers such as FDG-labelled leukocytes and gallium-68 PET tracers in this arena.

FDG-PET imaging in HIV infection and tuberculosis

The intersection and syndemic interaction between the human immunodeficiency virus (HIV) and tuberculosis (TB) epidemics have global prevalence with devastating morbidity and massive mortality. Using FDG-PET imaging it was shown that in HIV-infected individuals, involvement of the head and neck precedes that of the chest and of the abdomen. The sequence of lymph node involvement observed suggests the existence of a diffusible activation mediator that may be targeted via therapeutic intervention strategies. Furthermore, the degree of FDG uptake proved directly related to viral load and inversely related to CD4 cell count. Available data in acquired immune deficiency syndrome (AIDS)-defining cancers further suggest that FDG-PET/CT imaging may be useful for prognostication of cervical cancer and for identifying appropriate sites for biopsy, staging, and monitoring lymphoproliferative activity owing to HIV-associated Kaposi sarcoma and multicentric Castleman disease. Inversely, in HIV-associated lymphoma, FDG uptake in HIV-involved lymphoid tissue was shown to reduce the specificity of FDG-PET imaging findings, the effect of which in clinical practice warrants further investigation. In the latter setting, knowledge of viremia appears to be essential for FDG-PET image interpretation. Early HIV-associated neurocognitive disorder, formerly known as AIDS dementia complex, proved to be characterized by striatal hypermetabolism and progressive HIV-associated neurocognitive disorder or AIDS dementia complex by a decrease in subcortical and cortical metabolism. In lipodystrophic HIV-infected individuals, lipodystrophy proved associated with increased glucose uptake by adipose tissue, likely resulting from the metabolic stress of adipose tissue in response to highly active antiretroviral therapy. Furthermore, ongoing chronic low-grade infection in arteries of HIV-infected individuals could be depicted by FDG-PET/CT imaging. And there is promising data that FDG-PET/CT in HIV may serve as a new marker for the evaluation of thymic function in HIV-infected patients. In the setting of TB, FDG-PET has proven unable to differentiate malignancy from TB in patients presenting with solitary pulmonary nodules, including those suffering from HIV, and thus cannot be used as a tool to reduce futile biopsy or thoracotomy in these patients. In patients presenting with extrapulmonary TB, FDG-PET imaging was found to be significantly more efficient when compared with CT for the identification of more sites of involvement. Thus supporting that FDG-PET/CT can demonstrate lesion extent, serve as guide for biopsy with aspiration for culture, assist surgery planning and contribute to follow-up. Limited available data suggest that quantitative FDG-PET findings may allow for prediction or rapid assessment, at 4 months following treatment instigation, of response to antituberculostatics in TB-infected HIV patients. These results and more recent findings suggest a role for FDG-PET/CT imaging in the evaluation of therapeutic response in TB patients.

Concurrent FDG Avid Nasopharyngeal Lesion and Generalized Lymphadenopathy on PET-CT Imaging Is Indicative of Lymphoma in Patients with HIV Infection

Patients with HIV infection often have generalized lymphadenopathy and/or other lymphoid proliferation and are at significantly increased risk for lymphoma. This study retrospectively evaluated the diagnostic value of concurrent nasopharyngeal lesion and lymphadenopathy on positron emission tomography-computed tomography (PET-CT) with fluorine-18 fluorodeoxyglucose (FDG PET-CT) imaging. The eligible cases were from patients with HIV infection and lymphadenopathy and referred for FDG PET-CT to evaluate lymphoma or other malignancies prior to pathological investigation. FDG PET-CT images and interpretation reports were correlated with clinical information and pathological diagnoses. Among 22 eligible patients, FDG avid nasopharyngeal lesions were incidentally noted in 7 on PET-CT imaging, and all had lymphomas diagnosed with subsequent biopsies (6 diffuse large B-cell lymphomas and 1 Hodgkin's lymphoma). In the remaining 15 patients with adenopathy but no visible nasopharyngeal lesion or uptake on PET-CT imaging, 9 had biopsies and lymphomas were diagnosed in 4. The patients with FDG avid retroperitoneal or intra-abdominal lymphadenopathy had a greater possibility of lymphoma, compared to those with adenopathy localized only in the upper torso. Coexistent FDG avid nasopharyngeal lesion and generalized lymphadenoapthy on PET-CT imaging are indicative of a malignant lymphoma rather than benign lymphproliferative disease or nasopharyngeal carcinoma.