The role of 18F-FDG PET or PET/CT in the detection of fever of unknown origin. Eur J Radiol. 2012;81:3524-3529. [PMID: 22766321 DOI: 10.1016/j.ejrad.2012.05.025]

Role of 18 F-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 ± 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.

The Utility of 18FDG-PET/CT in Diagnosing Fever of Unknown Origin: The Experience of a Large Tertiary Medical Center

Fever of unknown origin (FUO) poses a diagnostic challenge, and 18-fluorodexoyglucose positron emission tomography with computed tomography (18FDG-PET/CT) may identify the source. We aimed to evaluate the diagnostic yield of 18FDG-PET/CT in the work-up of FUO. The records of patients admitted to Sheba Medical Center between January 2013 and January 2018 who underwent 18FDG-PET/CT for the evaluation of FUO were reviewed. Following examination of available medical test results, 18FDG-PET/CT findings were assessed to determine whether lesions identified proved diagnostic. Of 225 patients who underwent 18FDG-PET/CT for FUO work-up, 128 (57%) met inclusion criteria. Eighty (62.5%) were males; mean age was 59 ± 20.3 (range: 18-93). A final diagnosis was made in 95 (74%) patients. Of the 128 18FDG-PET/CT tests conducted for the workup of FUO, 61 (48%) were true positive, 26 (20%) false positive, 26 (20%) true negative, and 15 (12%) false negative. In a multivariate analysis, weight loss and anemia were independently associated with having a contributary results of 18FDG-PET/CT. The test yielded a sensitivity of 70%, specificity of 37%, positive predictive value of 70%, and negative predictive value of 37%. 18FDG-PET/CT is a valuable tool in the diagnostic workup of FUO. It proved effective in diagnosing almost half the patients, especially in those with anemia and weight loss.

Intravascular large B-cell lymphoma presenting with altered mental status: A case report

BACKGROUND

Intravascular large B-cell lymphoma (IVLBCL) is a rare and aggressive subtype of non-Hodgkin lymphoma with a varied presentation and no pathognomonic findings. Early diagnosis is critical to altering the disease course as early treatment with chemoimmunotherapy is required to prevent a rapidly fatal outcome. Strategies including improved awareness of this clinical entity through publication of cases with unique presentations are essential to prompt consideration of IVLBCL early in the disease workup. Here, we present a case of IVLBCL presenting with altered mental status and systemic organ dysfunction.

CASE SUMMARY

A 61-year-old male patient presented with flu-like symptoms and a high fever. He experienced rapid clinical deterioration with liver, kidney failure, and shock despite rapid antibiotic administration and supportive care. A broad infectious workup was negative. Intracranial imaging revealed nonspecific changes to the corpus callosum suspicious for vasculitis. Renal biopsy was non-diagnostic. After further progression of his symptoms, the family elected to withdraw care and the patient died shortly thereafter. Post-mortem analysis revealed clear multi-organ involvement by IVLBCL, prompting re-examination of the ante-mortem renal biopsy that also identified IVLBCL involvement.

CONCLUSION

IVLBCL is a rare disease. Communication with specialties and early biopsy is critical to establishing the diagnosis and initiating therapy.

Biodistribution and Radiation Dosimetry of the Enterobacteriaceae-Specific Imaging Probe [(18)F]Fluorodeoxysorbitol Determined by PET/CT in Healthy Human Volunteers

PURPOSE

[(18)F]fluorodeoxysorbitol ([(18)F]FDS) is the first radiopharmaceutical specific for a category of bacteria and has the potential to specifically detect Enterobacteriaceae infections. The purpose of this study was to testify the safety and investigate the biodistribution and radiation dosimetry of [(18)F]FDS in healthy human bodies.

PROCEDURES

Six healthy subjects were intravenously injected with 320-520 MBq [(18)F]FDS. On each subject, 21 whole-body emission scans and a brain scan were conducted at settled time points within the next 4 h. Residence time for each source organ was determined by multi-exponential regression. Absorbed doses for target organs and effective dose were calculated via OLINDA/EXM.

RESULTS

No adverse events due to [(18)F]FDS injection were observed in the study. The tracer was cleared rapidly from the blood pool through the urinary system. A small portion was cleared into the gut through the hepatobiliary system. The effective dose (ED) was estimated to be 0.021 ± 0.001 mSv/MBq. The organ receiving the highest absorbed dose was the urinary bladder wall (0.25 ± 0.03 mSv/MBq).

CONCLUSIONS

[(18)F]FDS is safe and well tolerated. The effective dose was comparable to that of other F-18 labeled radiotracers. [(18)F]FDS is suitable for human use from a radiation dosimetry perspective.

The efficacy of 18F-FDG PET/CT and 67Ga SPECT/CT in diagnosing fever of unknown origin

OBJECTIVE

Fever of unknown origin (FUO) is a diagnostic challenge. This study aimed to assess the efficacy of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and gallium-67 single-photon emission computed tomography/computed tomography (⁶⁷Ga SPECT/CT) in diagnosing FUO.

METHODS

A total of 68 patients with FUO underwent ¹⁸F-FDG PET/CT and ⁶⁷Ga SPECT/CT from January 2013 through May 2016. Images were read independently. The imaging results were compared with the final diagnosis and categorized as helpful for diagnosis or non-contributory to diagnosis in the clinical setting. Associations between categorical variables were evaluated with the chi-square test or Fisher's exact test.

RESULTS

Ten of the 68 patients were excluded. An infectious underlying disease was found in 23 patients. A malignant disorder was the cause of FUO in 10 patients. Non-infectious inflammatory disease was found in 11 patients. Adrenal insufficiency was the cause of FUO in two patients. The cause of FUO was not found for 12 patients. A high false-positive rate of 44% (7/16) was observed for ¹⁸F-FDG PET/CT, while a high false-negative rate of 55% (23/42) was observed for ⁶⁷Ga SPECT/CT. ¹⁸F-FDG PET/CT studies depicted all ⁶⁷Ga-avid lesions. The sensitivity (79% vs. 45%) and clinical contribution (72% vs. 55%) of ¹⁸F-FDG PET/CT in diagnosing FUO were significantly higher than those of ⁶⁷Ga SPECT/CT (p<0.05).

CONCLUSIONS

On the basis of this study, the diagnostic performance of ¹⁸F-FDG PET/CT is superior to ⁶⁷Ga SPECT/CT in the work-up of patients with FUO. With its rapid results and superior sensitivity, ¹⁸F-FDG PET/CT may replace ⁶⁷Ga SPECT/CT where this technique is available.

The Value of 18F-FDG PET/CT in Diagnostic Procedure of Intravascular Large B-Cell Lymphoma Presenting Fever of Unknown Origin and Pulmonary Hypertension as an Initial Manifestation

A 57-year-old man presented with fever of unknown origin and pulmonary hypertension. An F-FDG PET/CT scan was performed to evaluate the source of fever, which showed diffuse, homogeneously increased FDG uptake in both lungs, which prompted the transbronchial lung biopsy. The pathological examination from biopsy specimen demonstrated intravascular large B-cell lymphoma.

Fever of unknown origin revealed to be primary splenic lymphoma: A rare case report with review of the literature

Fever is a common clinical presentation of a number of diseases. A sustained unexplained fever >38.3°C lasting for >3 weeks without an established diagnosis despite intensive diagnostic evaluation is referred to as fever of unknown origin (FUO). FUO remains a clinical challenge for physicians, as it may be attributed to a wide range of disorders, mainly infections, malignancies, non-infectious inflammatory diseases and miscellaneous diseases. We herein report the case of a 59-year-old male patient who presented with prolonged unexplained fever and was found to have a diffusely enlarged hypermetabolic spleen, as shown on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography examination. Following splenectomy, histopathological examination revealed primary splenic lymphoma (PSL) of B-cell origin. The patient received 6 courses of systemic chemotherapy with rituximab, etoposide, cyclophosphamide, doxorubicin, vincristine and prednisone (R-ECHOP regimen) and responded well to treatment. Thus, in patients with FUO and splenomegaly, the possibility of PSL should be taken into consideration.

The role of ¹⁸F-FDG PET or ¹⁸F-FDG-PET/CT in the evaluation of solitary pulmonary nodules

Even with the recent advance in diagnostic tools and techniques, solitary pulmonary nodules (SPNs) remains a major clinical challenge for all doctors involved in their study. There are a wide range of diagnoses of benign and malignant lesions that can manifest as SPNs. Positron emission tomography (PET) or positron emission tomography/computed tomography (PET/CT) makes a great contribution to the diagnosis and differential diagnosis of SPNs due to the high sensitivity of pathological accumulation of (18)F-FDG. Owing to integrates the anatomical morphological and metabolic aspects in a single examination, high sensitivity and the ability to perform whole-body scans, combined PET/CT improving overall diagnosis accuracy.

Prolonged and recurrent fevers in children

Some children referred for prolonged fever are actually not having elevated temperatures; the approach here requires dissection of the history and correction of health misperceptions. Others have well-documented fevers associated with clinical, laboratory, or epidemiologic findings that should point to a specific diagnosis. "Fever-of-Unknown-Origin" (FUO) is the clinical scenario of daily fever for ≥ 14 days that defies explanation after a careful history, physical examination, and basic laboratory tests. The diagnostic approach requires a meticulous fever diary, serial clinical and laboratory evaluations, vigilance for the appearance of new signs and symptoms, and targeted investigations; the pace of the work-up is determined by the severity of the illness. Approximately half of children with FUO will have a self-limited illness and will never have a specific diagnosis made; the other half will ultimately be found to have, in order, infectious, inflammatory, or neoplastic conditions. Irregular, intermittent, recurrent fevers in the well-appearing child are likely to be sequential viral illnesses. Monogenic autoinflammatory diseases should be considered in those who do not fit the picture of recurrent infections and who do not have hallmarks of immune deficiency. Stereotypical febrile illnesses that recur with clockwork periodicity should raise the possibilities of cyclic neutropenia, if the cycle is approximately 21 days, or periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome, the most common periodic fever in childhood.