Fluorodeoxyglucose Positron Emission Tomography integrated with computed tomography in carcinoma of the cervix: Its impact on accurate staging and the predictive role of its metabolic parameters

The role of 18F-FDG PET/CT metabolic parameters in the differential diagnosis of post-transplant lymphoproliferative disorder after pediatric liver transplantation

Background

Post-transplant lymphoproliferative disorder (PTLD) is a significant complication after liver transplantation. Research on the diagnostic value of the Fluorine-18 fluorodeoxyglucose positron emission tomography/computerized tomography (18F-FDG PET/CT) metabolic parameters of PTLD in pediatric liver transplantation (pLT) recipients is limited. This study sought to evaluate the diagnostic efficacy of 18F-FDG PET/CT in differentiating between PTLD and non-PTLD lymphadenopathy in pLT recipients.

Methods

This retrospective study collected the 18F-FDG PET/CT scans with clinical and pathological information of all consecutive children who were clinically suspected of PTLD from November 2016 to September 2022 at the Beijing Friendship Hospital. The 18F-FDG PET/CT metabolic parameters of the two groups were analyzed. We then established a diagnostic model composed of the clinical characteristics and metabolic parameters.

Results

In total, 57 eligible patients were enrolled in this study, of whom 40 had PTLD and 17 had non-PTLD lymphadenopathy. Of the metabolic parameters examined in this study, total lesion glycolysis (TLG) had the highest area under the curve (AUC) value [0.757, 95% confidence interval (CI): 0.632-0.883, P=0.002]. The AUCs of the other metabolic parameters were all less than the AUC of TLG, including the maximum standardized uptake value (SUVmax) (AUC: 0.725, 95% CI: 0.597-0.853, P=0.008), mean standardized uptake value (SUVmean) (AUC: 0.701, 95% CI: 0.568-0.834, P=0.017), metabolic tumor volume total (MTVtotal) (AUC: 0.688, 95% CI: 0.549-0.827, P=0.040), TLG total (AUC: 0.674, 95% CI: 0.536-0.812, P=0.026). The diagnostic model, which was composed of clinical characteristics (digestive symptoms), the SUVmax, TLG, and the MTVtotal, showed excellent performance in the differential diagnosis (sensitivity: 0.675, 95% CI: 0.508-0.809; specificity: 0.941, 95% CI: 0.692-0.997; positive predictive value: 0.964, 95% CI: 0.798-0.998; and negative predictive value: 0.552, 95% CI: 0.360-0.730).

Conclusions

The 18F-FDG PET/CT metabolic parameters can be used to distinguishing between PTLD and non-PTLD lymphadenopathy in pLT recipients.

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.

Differences between [18F]FLT and [18F]FDG Uptake in PET/CT Imaging in CC Depend on Vaginal Bacteriology

This study aims to investigate if vaginal bacteriology obtained prior to treatment influences the 3′-deoxy-3 18F-fluorothymidine (FLT) [¹⁸F]FLT and 2-deoxy-2-[¹⁸F]fluoro-d-glucose (2-[¹⁸F]FDG) [¹⁸F]FDG parameters in positron emission tomography (PET/CT) in cervical cancer (CC) patients. Methods: Retrospective analysis was performed on 39 women with locally advanced histologically confirmed cervical cancer who underwent dual tracer PET/CT examinations. The [¹⁸F]FLT and [¹⁸F]FDG PET parameters in the primary tumor, including SUVmax, SUVmean, MTV, heterogeneity, before radiotherapy (RT) were analyzed, depending on the bacteriology. The p-values < 0.05 were considered statistically significant. Results: In the vaginal and/or cervical smears, there were 27 (79.4%) positive results. In seven (20.6%) cases, no opportunistic pathogen growth was observed (No Bacteria Group). In positive bacteriology, eleven (32%) Gram-negative bacilli (Bacteria group 2) and fifteen (44%) Gram-positive bacteria (Bacteria group 1) were detected. Five patients with unknown results were excluded from the analysis. Data analysis shows a statistically significant difference between the SUV_max, and SUV_min values for three independent groups for the [¹⁸F]FLT. Conclusions: The lowest values of SUV_max and SUV_min for [¹⁸F]FLT are registered in Gram-negative bacteria, higher are in Gram-positive, and the absence of bacteria causes the highest [¹⁸F]FLT values.

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.

HIV status does not have an impact on positron emission tomography-computed tomography (PET-CT) findings or radiotherapy treatment recommendations in patients with locally advanced cervical cancer

INTRODUCTION

Positron emission tomography-computed tomography (PET-CT) imaging is commonly used to identify nodal involvement in locally advanced cervical carcinoma, but its appropriateness for that purpose among HIV-positive patients has rarely been studied. We analyzed PET-CT findings and subsequent treatment prescribed in patients with locally advanced cervical carcinoma in Cape Town, South Africa.

METHODS

We identified a cohort of consecutive cervical carcinoma patients International Federation of Gynecology and Obstetrics (FIGO) stage IIB to IIIB at our cancer center who underwent a planning 18-fluorodeoxyglucose (¹⁸FDG) PET-CT scan from January 2015 through December 2018. Demographics, PET-CT findings, and subsequent treatment prescribed were recorded. Patients were selected for PET-CT only if they had no signs of distant disease on staging chest X-ray or abdominal ultrasound; were deemed suitable for radical chemoradiation by the multi-disciplinary team; and had normal renal function. HIV-positive patients ideally had to have been established on continuous antiviral therapy for more than 3 months and to have a CD4 cell count above 150 cells/μL. Small cell and neuroendocrine carcinoma cases were excluded from the study. Differences in demographic and clinical measures between HIV-positive and HIV-negative patients were evaluated by means of t-tests for continuous variables and χ² tests for categorical variables.

RESULTS

Over a 4 year period, 278 patients-192 HIV-negative (69.1%) and 86 HIV-positive (30.9%)-met the inclusion criteria. HIV-positive patients had a median CD4 count of 475 cells/µL (IQR 307-612 cells/µL). More than 80% of patients had pelvic nodal involvement, and more than 40% had uptake in common iliac and/or para-aortic nodes. Nodal involvement was not associated with HIV status. Fifty-four patients (19.4%) had at least one site of distant metastatic disease. Overall, 235 patients (84.5%) were upstaged following PET-CT staging scan. Upstaging was not associated with HIV status (HIV-negative 83.9% vs HIV-positive 87.2%; p=0.47). Ten patients who did not return for radiotherapy were excluded from the analysis. Following their PET-CT scan, treatment intent changed for 124 patients (46.3%): 53.6% of HIV-positive patients and 42.9% of HIV-negative patients (p=0.11).

CONCLUSION

We found no differences between HIV-positive or HIV-negative patients in nodal involvement or occult metastases, and PET-CT imaging did not lead to, or justify, treatment differences between the two groups. Future studies will evaluate survival and correlation of upstaging with outcome.