Usefulness of FDG PET/CT in the management of tuberculosis

Distributable, metabolic PET reporting of tuberculosis

Tuberculosis remains a large global disease burden for which treatment regimens are protracted and monitoring of disease activity difficult. Existing detection methods rely almost exclusively on bacterial culture from sputum which limits sampling to organisms on the pulmonary surface. Advances in monitoring tuberculous lesions have utilized the common glucoside [18F]FDG, yet lack specificity to the causative pathogen Mycobacterium tuberculosis (Mtb) and so do not directly correlate with pathogen viability. Here we show that a close mimic that is also positron-emitting of the non-mammalian Mtb disaccharide trehalose - 2-[18F]fluoro-2-deoxytrehalose ([18F]FDT) - is a mechanism-based reporter of Mycobacteria-selective enzyme activity in vivo. Use of [18F]FDT in the imaging of Mtb in diverse models of disease, including non-human primates, successfully co-opts Mtb-mediated processing of trehalose to allow the specific imaging of TB-associated lesions and to monitor the effects of treatment. A pyrogen-free, direct enzyme-catalyzed process for its radiochemical synthesis allows the ready production of [18F]FDT from the most globally-abundant organic 18F-containing molecule, [18F]FDG. The full, pre-clinical validation of both production method and [18F]FDT now creates a new, bacterium-selective candidate for clinical evaluation. We anticipate that this distributable technology to generate clinical-grade [18F]FDT directly from the widely-available clinical reagent [18F]FDG, without need for either custom-made radioisotope generation or specialist chemical methods and/or facilities, could now usher in global, democratized access to a TB-specific PET tracer.

Dual-energy computed tomography for evaluating nodal staging in lung adenocarcinoma: correlation with surgical pathology

PURPOSE

To ascertain the performance of dual-energy CT (DECT) with iodine quantification in differentiating malignant mediastinal and hilar lymph nodes (LNs) from benign ones, focusing on patients with lung adenocarcinoma.

MATERIALS AND METHODS

In this study, patients with suspected lung cancer received a preoperative contrast-enhanced DECT scan from Jun 2018 to Dec 2020. Quantitative DECT parameters and the size were compared between metastatic and benign LNs. Their diagnostic performances were analyzed by the ROC curves and compared by using the two-sample t test.

RESULTS

72 patients (23 men, 49 women; mean age 62.5 ± 10.1 years) fulfilled the inclusion criteria. A total of 98 LNs (67 benign, 31 metastatic) were analyzed. The iodine concentration normalized by muscle (NICmuscle) was significantly higher (P < 0.001) in metastatic LNs (4.79 ± 1.70) than in benign ones (3.00 ± 1.45). The optimal threshold of NICmuscle was 3.44, which yielded AUC: 0.798, sensitivity: 83.9%, specificity: 73.1%, accuracy: 76.5%, respectively. Applying the established size parameters with 10 mm as the threshold yielded AUC: 0.600, sensitivity: 29.0%, specificity: 91.0%, accuracy: 71.4%, respectively. The diagnostic performance of NICmuscle was significantly better (P = 0.007) than the performance obtained using the established size parameters.

CONCLUSIONS

For lung adenocarcinoma, the quantitative measurement of NICmuscle derived from DECT is useful for differentiating benign and metastatic mediastinal and hilar LNs before surgical intervention.

Tuberculous peritonitis diagnosed following laparoscopic examination for suspected advanced ovarian cancer

Laparoscopy for intra-abdominal exploration and tissue sampling is useful in advanced ovarian cancers, in which it is presumed to be difficult to achieve complete tumour reduction in the initial surgery. This is a report of a case of suspected advanced ovarian cancer in a patient, who underwent laparoscopic screening and was later pathologically diagnosed with tuberculous peritonitis. A woman in her 50s visited her local doctor with constipation. Since imaging showed massive ascites she was referred for further evaluation. We initially suspected advanced ovarian cancer due to the presence of massive ascites and multiple peritoneal nodules. However, histopathological examination indicated that the nodules were tubercles, and the patient was subsequently diagnosed with tuberculous peritonitis. It is important to be aware that tuberculosis peritonitis can be misdiagnosed or mistaken for advanced ovarian cancer. Preoperative diagnosis of tuberculous peritonitis is often difficult. Tuberculous peritonitis should be considered if intraoperative findings show diffuse nodular disseminated lesions.

Imaging of infra-thoracic tuberculosis

Tuberculosis (TB) is a potentially curable disease that is a leading cause of death globally. While it typically affects the lungs, this disease may involve many extra-pulmonary sites, particularly in patients with risk factors. Extra-pulmonary TB often mimics a variety of different diseases, posing a diagnostic dilemma. Imaging aids in early diagnosis of TB, especially in patients with non-specific or atypical symptoms found at extra-pulmonary infra-thoracic locations. Imaging also helps guide appropriate laboratory investigation, monitor disease progress, and response to treatment. This review aims to highlight the imaging spectrum of TB affecting the infra-thoracic region, that is, gastrointestinal tract, abdominal lymph nodes, peritoneal cavity, intra-abdominal solid organs, and urogenital system.

Distributable, Metabolic PET Reporting of Tuberculosis

Tuberculosis remains a large global disease burden for which treatment regimens are protracted and monitoring of disease activity difficult. Existing detection methods rely almost exclusively on bacterial culture from sputum which limits sampling to organisms on the pulmonary surface. Advances in monitoring tuberculous lesions have utilized the common glucoside [18F]FDG, yet lack specificity to the causative pathogen Mycobacterium tuberculosis (Mtb) and so do not directly correlate with pathogen viability. Here we show that a close mimic that is also positron-emitting of the non-mammalian Mtb disaccharide trehalose - 2-[18F]fluoro-2-deoxytrehalose ([18F]FDT) - can act as a mechanism-based enzyme reporter in vivo. Use of [18F]FDT in the imaging of Mtb in diverse models of disease, including non-human primates, successfully co-opts Mtb-specific processing of trehalose to allow the specific imaging of TB-associated lesions and to monitor the effects of treatment. A pyrogen-free, direct enzyme-catalyzed process for its radiochemical synthesis allows the ready production of [18F]FDT from the most globally-abundant organic 18F-containing molecule, [18F]FDG. The full, pre-clinical validation of both production method and [18F]FDT now creates a new, bacterium-specific, clinical diagnostic candidate. We anticipate that this distributable technology to generate clinical-grade [18F]FDT directly from the widely-available clinical reagent [18F]FDG, without need for either bespoke radioisotope generation or specialist chemical methods and/or facilities, could now usher in global, democratized access to a TB-specific PET tracer.

Nonmalignant Thoracic Disorders: An Appraisal of Fluorodeoxyglucose and Non-fluorodeoxyglucose PET/Computed Tomography Applications

PET/computed tomography (CT) with fluorodeoxyglucose and nonfluorodeoxyglucose PET tracers has established itself in the management of malignant disorders. Its role in the assessment of nonmalignant conditions, such as infectious and noninfectious inflammatory diseases and other benign conditions, has emerged independently and alongside its role being evaluated in malignancy and continues to evolve. It is evident that PET/CT has the potential to play a significant role in various nonmalignant disorders of the thorax. This review highlights current developments and areas where PET/CT has a potential to impact the clinical management of nonmalignant thoracic conditions with special focus on nonfluorodeoxyglucose tracers.

Changes in Metabolism as a Diagnostic Tool for Lung Cancer: Systematic Review

Lung cancer is the leading cause of cancer-related mortality worldwide, with five-year survival rates varying from 3–62%. Screening aims at early detection, but half of the patients are diagnosed in advanced stages, limiting therapeutic possibilities. Positron emission tomography-computed tomography (PET-CT) is an essential technique in lung cancer detection and staging, with a sensitivity reaching 96%. However, since elevated 18F-fluorodeoxyglucose (¹⁸F-FDG) uptake is not cancer-specific, PET-CT often fails to discriminate between malignant and non-malignant PET-positive hypermetabolic lesions, with a specificity of only 23%. Furthermore, discrimination between lung cancer types is still impossible without invasive procedures. High mortality and morbidity, low survival rates, and difficulties in early detection, staging, and typing of lung cancer motivate the search for biomarkers to improve the diagnostic process and life expectancy. Metabolomics has emerged as a valuable technique for these pitfalls. Over 150 metabolites have been associated with lung cancer, and several are consistent in their findings of alterations in specific metabolite concentrations. However, there is still more variability than consistency due to the lack of standardized patient cohorts and measurement protocols. This review summarizes the identified metabolic biomarkers for early diagnosis, staging, and typing and reinforces the need for biomarkers to predict disease progression and survival and to support treatment follow-up.

Analysis of misdiagnosis and 18F-FDG PET/CT findings of lymph node tuberculosis

OBJECTIVE

To investigate 18F-FDG PET/CT findings of tuberculous lymphadenitis and analyze the causes of misdiagnosis.

METHOD

Between 2013 and 2021, a retrospective review was conducted on 22 patients at Jiangxi Provincial People's Hospital Affiliated with Nanchang University who had lymph node tuberculosis confirmed by histology or clinical investigation. Subjective judgment and quantitative analysis were adopted.

RESULTS

Out of 22 patients, 14 are male and 8 are female. The average age was 55.5 years (55.5±12.4). The most common site of lymph node tuberculosis (LNTB) is the mediastinum (41.5%), followed by the neck (24.4%) and the abdominal cavity (21.9%). Half of the patients have more than one site affected. More than half of LNTB patients (54.5%) are concurrent with other types of TB, especially PTB. Among the 41 biggest affected lymph nodes, the average maximum diameter, minimum diameter, SUVmax and the lesion SUVmax/SUVmean liver ratio are 22.04±8.39, 16.93±6.75, 9.72±5.04 and 6.72±3.60, respectively. There is a poor correlation coefficient of 0.236 between the FDG uptake and the size of the biggest affected lymph node. Patients who are concurrent with no other TB have the significantly higher FDG uptake than patients who are concurrent with other TB (12.42 vs 8.02) (p = 0.005). Among these cases, 6 cases (27.3%) are accurately diagnosed with LNTB, all of which have pulmonary tuberculosis as a complication. However, 16 cases (72.7%) are misdiagnosed as lymphoma (50%), sarcoidosis (13.6%), and lymph node metastasis (9%).

CONCLUSIONS

This study demonstrates that 18F-FDG PET/CT is very useful in detecting LNTB because tuberculous granulomas show significant levels of glucose uptake. It proves to be an effective method for revealing lesion extent and discovering additional lesions that morphological imaging is missed. However, 18F-FDG PET/CT is not able to reliably distinguish LNTB from lymphoma, sarcoidosis, and metastatic lymph nodes. Nonetheless, 18F-FDG PET/CT allows for the selection of the most optimal biopsy location, and thus has potential to detect early treatment response and distinguish between active and inactive lesions.

Impact of PET/CT among patients with suspected mycotic aortic aneurysms

Purpose

To determine the impact of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) on clinical management in patients with suspected mycotic aortic aneurysms (MAA).

Materials and methods

For this observational cohort study 101 PET/CT were acquired in 50 patients, thereof 50 for the initial diagnosis/baseline scan, 51 for follow-up. Impact on patient management was defined in three categories: PET/CT results were “confirmed” (by clinical follow-up), “suspected” (conclusive, not confirmed), or “misleading” (proven wrong by follow-up). For clinical follow-up patient data were recorded at the time of imaging, and at the latest recorded clinical visit. It included patient demographics, clinical information, laboratory data, results of microbiology and other diagnostic procedures, information about treatment, and patient’s general health condition.

Results

In four patients (8%) no clinical follow-up was feasible, the other 46 patients were clinically followed for a median of 898 days (IQR 320–4105). The combined evaluation of all 101 PET/CT demonstrated an impact on patient management in 78,5% of cases (48,5% confirmed, 30% suspected). Results of 21,5% of the PET/CT examinations were misleading. Respective values at baseline and at follow-up were: impact on patient management in 82% and 74,5% (70% and 27.5% confirmed, and 12% and 47% suspected), misleading cases in 18% and 25.5%.

Conclusion

In MAA, PET/CT has a high impact on patient management, which is more pronounced with baseline than with follow-up examinations. However, PET/CT results may be misleading in a smaller proportion of cases.

Evolutionary Views of Tuberculosis: Indoleamine 2,3-Dioxygenase Catalyzed Nicotinamide Synthesis Reflects Shifts in Macrophage Metabolism: Indoleamine 2,3-Dioxygenase Reflects Altered Macrophage Metabolism During Tuberculosis Pathogenesis

Indoleamine 2,3-dioxygenase (IDO) is the rate-limiting enzyme in conversion of tryptophan to kynurenines, feeding de novo nicotinamide synthesis. IDO orchestrates materno-foetal tolerance, increasing human reproductive fitness. IDO mediates immune suppression through depletion of tryptophan required by T lymphocytes and other mechanisms. IDO is expressed by alternatively activated macrophages, suspected to play a key role in tuberculosis (TB) pathogenesis. Unlike its human host, Mycobacterium tuberculosis can synthesize tryptophan, suggesting possible benefit to the host from infection with the microbe. Intriguingly, nicotinamide analogues are used to treat TB. In reviewing this field, it is postulated that flux through the nicotinamide synthesis pathway reflects switching between aerobic glycolysis and oxidative phosphorylation in M. tuberculosis-infected macrophages. The evolutionary cause of such shifts may be ancient mitochondrial behavior related to reproductive fitness. Evolutionary perspectives on the IDO pathway may elucidate why, after centuries of co-existence with the Tubercle bacillus, humans still remain susceptible to TB disease.

Retention of 64Cu-FLFLF, a Formyl Peptide Receptor 1-Specific PET Probe, Correlates with Macrophage and Neutrophil Abundance in Lung Granulomas from Cynomolgus Macaques

Neutrophilic inflammation correlates with severe tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (Mtb). Granulomas are lesions that form in TB, and a PET probe for following neutrophil recruitment to granulomas could predict disease progression. We tested the formyl peptide receptor 1 (FPR1)-targeting peptide FLFLF in Mtb-infected macaques. Preliminary studies in mice demonstrated specificity for neutrophils. In macaques, 64Cu-FLFLF was retained in lung granulomas and analysis of lung granulomas identified positive correlations between 64Cu-FLFLF and neutrophil and macrophage numbers (R2 = 0.8681 and 0.7643, respectively), and weaker correlations for T cells and B cells (R2 = 0.5744 and 0.5908, respectively), suggesting that multiple cell types drive 64Cu-FLFLF avidity. By PET/CT imaging, we found that granulomas retained 64Cu-FLFLF but with less avidity than the glucose analog 18F-FDG. These studies suggest that neutrophil-specific probes have potential PET/CT applications in TB, but important issues need to be addressed before they can be used in nonhuman primates and humans.

Pre treatment and post treatment positron emission tomography-computed tomography (PET-CT) to evaluate treatment response in tuberculous Tubo-Ovarian masses

PURPOSE

Female genital Tuberculosis (FGTB) causes infertility and formation of Tubo-ovarian (TO) masses. The study showed treatment response of PET-CT in evaluation of anti-tubercular treatment response in patients of infertility with tuberculous TO masses.

METHOD

It's a Prospective study on 47 confirmed cases of FGTB with infertility having TO masses. All patients were subjected to 18F-FDGPET/CT to see the glucose uptake by the TO mass and extent of the disease. Category I treatment under DOTS was given for 6 months. All underwent follow-up of PET/CT to see the response to ATT. Results of pre ATT PET/CT were compared with post ATT PET/CT.

RESULTS

TO masses was in 42 (89.36%); bilateral in 18 (38.29%) FDG uptake in 14 (29.78%) and without FDG uptake in 4 (8.51%) cases. Right sided mass in 13 (27.65%) FDG uptake in 9 (19.14%) and without FDG uptake in 4 (8.51%) cases. Left sided mass in 11 (23.40%) FDG uptake in 7 (14.89%) and without FDG uptake in 4 (8.51%) cases. Post ATT, there was significant decrease in most parameters. Repeat PET-CT done in 44 cases showed TO mass in 9 (20.45%); bilateral in 4 (9.09%) (FDG uptake in 2.27%) (p < 0.001), right sided in 3 (6.85%) (FDG uptake in 2.27%) (p < 0.002) and left side in 2 (2.27%) FDG uptake in 1 case (p < 0.004). Pelvic and mesenteric lymphadenopathy without FDG uptake was in 1 case (p value = 0.03) while omental and peritoneal deposits without FDG uptake in 1 and 2 cases, respectively.

CONCLUSION

PET-CT is useful in treatment response evaluation of tubercular TO masses.

The Role of 18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) in Management of Nocardiosis: A Retrospective Study and Review of the Literature

Introduction

18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is a well-established tool for managing metastatic infections. Nocardiosis, a primarily pulmonary infection, disseminates at high rates. Routine imaging includes chest CT and brain imaging. We examined the use of FDG-PET/CT in nocardiosis and assessed its contribution to diagnosis and management.

Methods

A retrospective study in two tertiary medical centers during 2011–2020. Individuals with nocardiosis for whom FDG-PET/CT was implemented for any reason were included and their medical records were reviewed. A board-certified nuclear medicine physician independently reviewed all scans. Additionally, a systematic review was conducted according to the PRISMA guidelines, to extract data from publications reporting FDG-PET/CT use for the management of nocardiosis.

Results

FDG-PET/CT contributed to the management of all seven patients who met inclusion criteria. It assisted in ruling out an underlying malignancy (29%, 2/7); establishing a wide infection extent (57%, 4/7); and affecting decisions regarding treatment (57%, 4/7), including drug regimen, oral step-down, and duration of therapy. We identified 20 published case reports on this topic. In 80% (16/20), FDG-PET/CT contributed to the management of nocardiosis similar to our study. In addition, in most of the literature cases, FDG-PET/CT guided the diagnostic biopsy.

Conclusion

FDG-PET/CT is valuable in the diagnosis and management of individuals with nocardiosis. The contribution of incorporating FDG-PET/CT to the management of individuals with nocardiosis and its role in monitoring treatment response and shortening treatment duration should be evaluated in prospective studies.

How Long Do We Need to Treat an Invasive Mold Disease in Hematology Patients? Factors Influencing Duration of Therapy and Future Questions

Treatment duration for invasive mold disease (IMD) in patients with hematological malignancy is not standardized and is a challenging subject in antifungal stewardship. Concerns for IMD relapse during subsequent reinduction or consolidation chemotherapy or graft versus host disease treatment in hematopoietic stem cell transplant recipients often results in prolonged or indefinite antifungal treatment. There are no validated criteria that predict when it is safe to stop antifungals. Decisions are individualized and depend on the offending fungus, site and extent of IMD, comorbidities, hematologic disease prognosis, and future plans for chemotherapy or transplantation. Recent studies suggest that FDG-PET/CT could help discriminate between active and residual fungal lesions to support decisions for safely stopping antifungals. Validation of noninvasive biomarkers for monitoring treatment response, tests for quantifying the "net state of immunosuppression," and genetic polymorphisms associated with poor fungal immunity could lead to a personalized assessment for the continued need for antifungal therapy.

Characterization of 18F-fluorodeoxyglucose metabolic spatial distribution improves the differential diagnosis of indeterminate pulmonary nodules and masses with high fluorodeoxyglucose uptake

Background

The aim of this study was to investigate the value of visual assessment of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) metabolic spatial distribution (V-FMSD) in the diagnosis of indeterminate pulmonary nodules and masses with high ¹⁸F-FDG uptake.

Methods

A total of 301 patients with indeterminate pulmonary nodules or masses who underwent ¹⁸F-FDG positron emission tomography/computed tomography (PET/CT) imaging were retrospectively studied. The characteristics of ¹⁸F-FDG metabolic spatial distribution (FMSD) in the proximal and distal regions of the lesions were visually analyzed using a 5-point scoring system. The sensitivity, specificity, accuracy, and area under receiver operating characteristic curve (AUC) were compared between V-FMSD and conventional PET/CT methods for the diagnosis of hypermetabolic indeterminate pulmonary nodules and masses.

Results

The V-FMSD results showed that 180 (92.8%) malignant lesions had a score of ≥3 and 78 (72.9%) benign lesions had a score of ≤2. This indicated that the FMSD in the proximal region of malignant lesions was significantly higher than that of the distal region, and the FMSD in the proximal region of benign lesions was significantly lower than that of the distal region. V-FMSD had a specificity of 72.9%, which was markedly higher than those of the maximum standard uptake value (SUV_max; 0%, P<0.001) and the retention index (RI; 26.2%, P<0.001). The AUC of V-FMSD was 0.886, which was significantly larger than those of the SUV_max (0.626, P<0.001), RI (0.670, P<0.001), and PET/CT (0.788, P<0.05).

Conclusions

Our study found that pulmonary benign and malignant lesions have distinct FMSD characteristics. V-FMSD can therefore be used as a novel auxiliary marker to improve the diagnostic accuracy of hypermetabolic indeterminate pulmonary nodules and masses.

State of the art of 18F-FDG PET/CT application in inflammation and infection: a guide for image acquisition and interpretation

AIM

The diagnosis, severity and extent of a sterile inflammation or a septic infection could be challenging since there is not one single test able to achieve an accurate diagnosis. The clinical use of 18F-fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT) imaging in the assessment of inflammation and infection is increasing worldwide. The purpose of this paper is to achieve an Italian consensus document on [¹⁸F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases, such as osteomyelitis (OM), prosthetic joint infections (PJI), infective endocarditis (IE), prosthetic valve endocarditis (PVE), cardiac implantable electronic device infections (CIEDI), systemic and cardiac sarcoidosis (SS/CS), diabetic foot (DF), fungal infections (FI), tuberculosis (TBC), fever and inflammation of unknown origin (FUO/IUO), pediatric infections (PI), inflammatory bowel diseases (IBD), spine infections (SI), vascular graft infections (VGI), large vessel vasculitis (LVV), retroperitoneal fibrosis (RF) and COVID-19 infections.

METHODS

In September 2020, the inflammatory and infectious diseases focus group (IIFG) of the Italian Association of Nuclear Medicine (AIMN) proposed to realize a procedural paper about the clinical applications of [¹⁸F]FDG PET/CT or PET/MRI in inflammatory and infectious diseases. The project was carried out thanks to the collaboration of 13 Italian nuclear medicine centers, with a consolidate experience in this field. With the endorsement of AIMN, IIFG contacted each center, and the pediatric diseases focus group (PDFC). IIFG provided for each team involved, a draft with essential information regarding the execution of [¹⁸F]FDG PET/CT or PET/MRI scan (i.e., indications, patient preparation, standard or specific acquisition modalities, interpretation criteria, reporting methods, pitfalls and artifacts), by limiting the literature research to the last 20 years. Moreover, some clinical cases were required from each center, to underline the teaching points. Time for the collection of each report was from October to December 2020.

RESULTS

Overall, we summarized 291 scientific papers and guidelines published between 1998 and 2021. Papers were divided in several sub-topics and summarized in the following paragraphs: clinical indications, image interpretation criteria, future perspectivess and new trends (for each single disease), while patient preparation, image acquisition, possible pitfalls and reporting modalities were described afterwards. Moreover, a specific section was dedicated to pediatric and PET/MRI indications. A collection of images was described for each indication.

CONCLUSIONS

Currently, [¹⁸F]FDG PET/CT in oncology is globally accepted and standardized in main diagnostic algorithms for neoplasms. In recent years, the ever-closer collaboration among different European associations has tried to overcome the absence of a standardization also in the field of inflammation and infections. The collaboration of several nuclear medicine centers with a long experience in this field, as well as among different AIMN focus groups represents a further attempt in this direction. We hope that this document will be the basis for a "common nuclear physicians' language" throughout all the country.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40336-021-00445-w.

18F-FDG PET-CT Diagnosis of Tuberculosis in Celiac Lymph Nodes

The special location of abdominal tuberculosis makes it difficult for biopsy, while its clinical and imaging characteristics make it indistinguishable from tumors. Here, we report a female patient that was initially misdiagnosed with pancreatic cancer, but eventually correctly diagnosed with tuberculosis in the celiac lymph nodes using ¹⁸F-FDG PET–CT. She was 38 years old. Her main complaint was “deep abdominal pain and discomfort for nearly a month”, accompanied by nausea and vomiting. Diagnosis of pancreatic tumors or enlarged lymph nodes was initially made based on CT scan results. Abdominal MRI revealed enlarged lymph nodes. ¹⁸F-FDG PET–CT imaging revealed a soft-tissue mass about 2.8 cm in diameter in the hepatic hilar area with a maximum standardized uptake value (SUV_max) of 9.4, and delayed imaging measured the SUV_max at 12. Enhanced CT showed no vascular envelopment in the mass. Based on these results, the patient was diagnosed with tuberculosis in the celiac lymph nodes. Her tuberculin test was strongly positive. After 5 months of antituberculosis treatment, the mass had reduced to about 1.5 cm in diameter and SUV_max reduced to 8.1, as demonstrated by ¹⁸F-FDG PET–CT imaging. Abdominal lymph-node tuberculosis is easy to misdiagnose, but timely ¹⁸F-FDG PET–CT imaging combined with tuberculin testing may reduce misdiagnosis and mistreatment.

18F-FDG PET/CT contribution to tuberculous vertebral osteomyelitis diagnosis: a case report

Tuberculous vertebral osteomyelitis (TVO) is an extrapulmonary tuberculosis form characterized by difficulty and delay in diagnosis. PET/CT is a valuable, well-established tool in the diagnostic workup of cancer and fever of unknown origin, which is increasingly appreciated in the management of infectious diseases. We report a TVO case where PET/CT had a valuable contribution towards diagnosis and monitoring of treatment response, highlighting its advantages and future perspectives when dealing with infectious diseases.

Radiosynthesis and preclinical evaluation of [18F]FEM as a potential novel PET probe for tumor imaging

In the 21st century, the incidence and mortality of cancer, one of the most challenging diseases in the world, have rapidly increased. The purpose of this study was to develop 2-(2-[¹⁸F]fluoroethoxy)ethyl 4-methylbenzenesulfonate ([¹⁸F]FEM) as a positron emission tomography (PET) agent for tumor imaging. In this study, [¹⁸F]FEM was synthesized with a good radiochemical yield (45.4 ± 5.8%), high specific radioactivity (over 25 GBq/μmol), and commendable radiochemical purity (over 99%). The octanol/water partition coefficient of [¹⁸F]FEM was 1.44 ± 0.04. The probe demonstrated good stability in vitro (phosphate-buffered saline (PBS) and mouse serum (MS)), and binding specificity to five different tumor cell lines (A549, PC-3, HCC827, U87, and MDA-MB-231). PET imaging of tumor-bearing mice showed that [¹⁸F]FEM specifically accumulated at the tumor site of the five different tumor cell lines. The average tumor-to-muscle (T/M) ratio was over 2, and the maximum T/M values reached about 3.5. The biodistribution and dynamic PET imaging showed that most probes were metabolized by the liver, whereas a small part was metabolized by the kidney. Moreover, dynamic brain images and quantitative data showed [¹⁸F]FEM can quickly cross the blood brain barrier (BBB) and quickly fade out, thereby suggesting it may be a promising candidate probe for the imaging of brain tumors. The presented results demonstrated that [¹⁸F]FEM is a promising probe for tumor PET imaging.