Role of 18F-FDG PET/CT for providing a targeted approach for etiology of PUO.

AIM: This study aimed to evaluate the potential role of 18F-fluorodeoxyglucose PET/computed tomography (18F-FDG PET/CT) in providing a targeted approach for diagnosing the etiology of Pyrexia of Unknown Origin (PUO). METHODS: A total of 573 PUO patients were included in this ambispective study, with a mean age of 39.40 ±â€…4.6 years. Patients underwent FDG PET/CT scans using dedicated hybrid scanners. PET/CT data were interpreted by experienced nuclear medicine physicians. The study analyzed the guidance provided by FDG PET/CT for appropriate biopsy sites and assessed concordance between PET/CT findings and histopathological examination. RESULTS: Out of the 573 patients, a final diagnosis was reached for 219 patients, including malignancy, infectious causes, noninfectious inflammatory causes (NIID), and precancerous conditions. FDG PET/CT played a crucial role in guiding clinicians to appropriate biopsy sites, contributing to a higher diagnostic yield. Concordance between PET/CT findings and histopathological examination emphasized the noninvasive diagnostic potential of PET/CT in identifying underlying causes of PUO. Overall, FDG PET/CT contributed to guiding the appropriate site of biopsy or concordance of the first differential diagnosis with the final diagnosis in 50.05% of cases. CONCLUSION: This study highlights the valuable role of FDG PET/CT in providing a targeted approach for diagnosing PUO, showcasing its potential in guiding clinicians towards appropriate biopsy sites and improving the diagnostic yield. The findings underscore the importance of integrating FDG PET/CT into the diagnostic pathway for PUO, ultimately enhancing patient management and outcomes. Further prospective studies are necessary to validate these results and refine the integration of FDG PET/CT in the diagnosis of PUO.

Discordant Molecular Imaging Findings with 2-[18F]FDG and [68Ga]Ga-PSMA PET/CT in a Patient with Both Bladder and Prostate Cancer.

The prevalence of double primary prostate and bladder cancer is not uncommon. Though both share a common pathway of malignant transformation, they bear to differ in the case of 2-[18F]FDG PET/CT and [68Ga]Ga-PSMA uptake. We present a case of double primary cancer involving the bladder and prostate, where the prostatic primary showed intense [68Ga]Ga-PSMA uptake with non-avid skeletal and pulmonary metastases, which showed intense 2-[18F]FDG uptake, thus showing discordance due to different clonal origins.

Unusual Male Breast Involvement in Burkitt Lymphoma Detected on Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Burkitt lymphoma (BL) is a poorly differentiated, aggressive form of B-cell non-Hodgkin's lymphoma. The clinical presentation of this disease is varied and may be nodal, extranodal, or both. BL of the breast, either primary or secondary, with bilateral breast involvement, is extremely rare. Herein, we present a case of BL in a 27-year-old male with unusual bilateral breast involvement.

Diagnostic accuracy of RBC scintigraphy and CTA for detection of patients with suspected lower gastrointestinal bleeding: a systematic review and meta-analysis.

OBJECTIVE: Detection of lower gastrointestinal bleeding (LGIB) through noninvasive modalities is very important in the successful management of LGIB. RBC scintigraphy and CT have a role in the detection of LGIB and guiding the management of patient by localization of the bleeding site. However, only a small number of studies have evaluated the role of RBC scintigraphy and CT in the diagnosis of LGIB. This systematic review was conducted to evaluate the diagnostic performance of RBC scintigraphy and CT in the detection of LGIB in patients with clinical or biochemical findings suspicious of LGIB. METHODS: This systematic review followed PRISMA guidelines. Searches in PubMed, Scopus, and Embase were conducted using relevant keywords, and articles published through 30 April 2022, were included. Using endoscopy or surgical outcomes as the reference standard, the numbers of true and false positives and true and false negatives were extracted. Pooled estimates of diagnostic test accuracy - including sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and summary ROC (SROC) curve - were generated using bivariate random-effects meta-analysis. RESULTS: Three studies comprising 171 patients were included in the systematic review and meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the detection of LGIB using RBC scintigraphy were 0.787 (95% CI, 0.643-0.893), 0.289 (95% CI, 0.164-0.443), 1.214 (95% CI, 0.923-1.597) and 0.576 (95% CI, 0.296-1.121) respectively. The area under the SROC curve was 0.73. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the detection of LGIB using CT were 0.931 (95% CI, 0.772-0.992), 0.870 (95% CI, 0.737-0.951), 6.085 (95% CI, 0.840-44.097), 0.126 (95% CI, 0.006-2.509) respectively. The area under the SROC curve was 0.095. CONCLUSION: RBC scintigraphy has overall good sensitivity and CTA has excellent sensitivity specificity, positive and negative likelihood ratio in the detection of LGIB in patients with clinical or biochemical findings suspicious for LGIB.CTA along with RBC scintigraphy can be used algorithmically to rule out patients who do not have a localization for the site of LGIB thereby helping these patients to avoid invasive procedures like endoscopy or surgical explorations.

Role of 18 F-FDG PET/CT in the diagnosis of benign vs. malignant tumor thrombus.

PURPOSE: Hypercoagulable state is a complication of various infections, and inflammatory processes and is a common scenario in cancer patients also. Timely diagnosis and treatment are essential to reduce further complications in such patients. The present study aimed to assess the role of FDG PET/CT in the diagnosis of benign vs. malignant tumor thrombus and to determine cut-off SUVmax to differentiate them. PATIENTS AND METHODS: We retrospectively reviewed all FDG PET/CT scans of patients done in our department from January 2017 to March 2022. All scans were reviewed by two experienced nuclear medicine physicians. A total of 135 patients who had venous or arterial thrombus in FDG PET/CT scans were included. All the FDG PET/CT scans of 135 patients were analyzed for primary tumor site and/or site of thrombus. Additional clinical data were collected for patients with benign conditions in the form of ESR and CRP if available and doubtful cases were followed up by HPE reports and/or CEMRI. The SUV max of the primary tumor(in cancer patients), thrombus, and background (aorta) were calculated. RESULTS: A total of 135 patients (108 cancer patients and 27 with benign thrombus) were included with an age range of 3 to 86 years (median 50 years). There were 91 males and 44 females. Of 108 cancer patients, the most common cancers were hepatocellular cancer - 38 (35.18%), renal cell cancer - 28(25.92%), and carcinoma of the thyroid - 6 (5.55%). Of 108 cancer patients, 36 (33.33%) had tumor thrombosis in inferior vena cava, 31 (28.70%) in the portal vein, and 41 (37.96%) in other vessels (renal vein, jugular vein, etc.). Of 27 patients with benign conditions,13 had venous thrombi, 11 had arterial thrombus and three had atrial thrombus and the most common thrombus sites were thoraco-abdominal aorta in seven (25.92%) and right atrium in three (11.11%) patients. In the subgroup of 108 oncological patients, the mean SUV max of the primary tumors was 17.67 (range 2.1-91.0; median 10.82), thrombi were 17.61 (range 2.14-90.11; median 14.56) and background was 5.29 (range 0.29-25.00; median 3.12). Of 27 patients with benign conditions, the mean SUV max of the thrombi was 11.09 (range 1.98-31; median 8.10) and the background was 9.80 (range 1.46-24.50; median 10.20) The ESR was raised in 13 of 26 patients (mean 35.84, range 10.98-62.00, median 35.00) and CRP was raised 22 of 26 patients (mean11.46, range 3.45-24.50, median 20.40). Upon plotting the receiver operating curve, a cutoff SUV max of 12.7 with a sensitivity of 62.96% and specificity of 77.77% was produced to demarcate tumor thrombus from benign thrombus. CONCLUSION: FDG PET/CT plays a significant role in the detection of thrombo-embolic disease and can differentiate benign thrombus from tumor thrombus.

Tc-99 m Ubiquicidin Imaging in Orbital Aspergilloma: an Illustration.

Aspergillus infection is relatively rare disease, and we present a case of orbital aspergillus infection who presented with right orbital pain and swelling. Right orbital lesion was identified on CT, MRI, and PET-CT imaging followed by confirmation of aspergillus on histopathological examination. We demonstrate that Tc-99 m ubiquicidin scan can yield positive results in aspergillosis too, enabling its differentiation from non-infective pathologies.

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.

Positron Emission Tomography/Computed Tomography in Thyroid Cancer.

Fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) plays an important role in the management of thyroid malignancies. Incidentally found FDG avid nodule needs further workup to rule out its malignant potential. 18F-FDG PET/CT has a proven role in detecting recurrent disease or the metastatic workup of the thyroglobulin elevated negative radioiodine scan (TENIS) scenario. In managing histologically aggressive carcinoma of the thyroid, 18F-FDG PET/CT has a proven role. The theranostic potential has been explored with PET/CT using 68Ga-SSA, 68Ga-PSMA,68Ga-FAPI, and 68Ga-DOTA-RGD. The 124I PET/CT role is just being investigated for better spatial resolution and helps in dosimetry.

Omicron Variant of COVID-19: Imaging Pattern on F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

We report a case of omicron infection in a biopsy-proven case of carcinoma breast sent for staging F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) during the omicron COVID wave. FDG PET/computed tomography (CT) revealed increased FDG uptake in nasopharyngeal, oropharynx, and tonsillar regions and bilateral cervical lymph nodes along with uptake in primary carcinoma and locoregional lymph nodes. Based on the clinical history and specific pattern of FDG PET/CT findings (as suggested by SNMMI Taskforce), COVID history and reverse transcription polymerase chain reaction positivity was elicited.

A Curious Case of Suspicious Lymphadenopathy in a Hereditary Spherocytosis Patient Reported as Extramedullary Hematopoiesis.

We present a case of a 23-year-old male patient with complaints of fever, cough, and persistent anemia for the past 6 months and with a known history of hereditary spherocytosis. Computed tomography (CT) thorax demonstrated multiple paravertebral lesions in the bilateral thoracic cavities, suggestive of lymphadenopathy; subsequently, 18Flurodeoxyglucose PET/CT was done with suspicion of lymphoma, which showed no significant metabolic activity in those lesions. Thus, in view of clinical and metabolic status, lesions were considered extramedullary hematopoiesis (EMH). This case highlights the importance of considering EMH, while interpreting suspicious lymphadenopathy in cases of chronic anemia and also possible scan findings in the same.

F-18 ML-104 tau PET imaging in mild cognitive impairment.

OBJECTIVE: This study was undertaken to evaluate the tau distribution patterns in patients with amnestic mild cognitive impairment (aMCI) using PET radiotracer F-18 ML-104. MATERIALS AND METHODS: Thirty patients, clinically diagnosed as aMCI [mini mental state evaluation ≥24] in the neurology or geriatric memory clinics, were included in the study. Each aMCI patient underwent F-18 fluorodeoxyglucose and F-18 ML-104 tau PET. Standardized uptake value ratios for cortical gray matter regions were evaluated for F-18 ML-104 tau PET and compared with normal controls and with early Alzheimer's disease (AD) patients (used from a previous study). RESULTS: aMCI revealed significantly higher standardized uptake value ratios in both medial temporal cortices, precuneus and posterior cingulate cortices in comparison to normal controls and a significantly lesser binding in bilateral medial and lateral temporal, precuneus and posterior cingulate cortices in comparison to early AD. A negative correlation was noted between F-18 fluorodeoxyglucose uptake and F-18 ML-104 retention in the precuneus and posterior cingulate cortices in aMCI, while F-18 ML-104 retention and mini mental state evaluation scores revealed a moderate negative correlation in the posterior cingulate cortices. CONCLUSION: We could demonstrate a significant increase in cortical tau deposition in aMCI patients in comparison to normal controls, thus providing in vivo evidence of the underlying pathological process in this subgroup of patients with high probability of conversion to AD.

An Unusual Case of Simultaneous Cricoid and Thyroid Cartilage Metastases from Prostatic Adenocarcinoma on 68Ga-PSMA PET/CT.

Although prostate cancer can metastasize to any part of the body, laryngeal cartilage metastasis is extremely rare and few cases have been published so far. Here we present the case of a 65-year-old male patient, recently diagnosed with prostate adenocarcinoma, referred for staging with 68Ga-PSMA PET/CT. He was found to have extensive skeletal metastasis along with cartilage metastasis involving both thyroid and cricoid cartilages.