Relationship Between the Elevated Muscle FDG Uptake in the Distal Upper Extremities on PET/CT Scan and Prescan Utilization of Mobile Devices in Young Patients

Muscle Involvement Caused by Chronic Active Epstein-Barr Virus Infection on 18F-FDG PET/CT in a Pediatric Patient

ABSTRACT

A 7-year-old girl with chronic active EBV (CAEBV) infection-associated hemophagocytic lymphohistiocytosis presented with fever. 18F-FDG PET/CT revealed heterogeneous FDG uptake in multiple muscle groups without significant abnormal activity elsewhere. On repeat FDG PET/CT scan 1 year later after therapy, the abnormal activity in muscles disappeared. Skeletal muscle involvement by CAEBV infection should be included as differential diagnosis for increased muscle activity on FDG PET/CT study.

Increased Genioglossus Muscle FDG Activity Due to Using Pacifier

ABSTRACT

An 18-month-old girl with history of liver transplant underwent FDG PET/CT to evaluate posttransplant lymphoproliferative disorder. In addition to multistation hypermetabolic lymphadenopathy and abnormal activity in the liver, stomach, and small bowel, in keeping with known posttransplant lymphoproliferative disorder, the images also showed focal activity in the submental region. This submental activity persisted on 2 separate follow-up FDG PET/CT studies, even though other foci of abnormal activity resolved after chemotherapy. Records revealed that the patient was sucking on a pacifier prior to all 3 FDG PET/CT studies, and the submental uptake corresponded with genioglossus muscle activity.

Physiological 2-deoxy-2-[fluorine-18] fluoro-D-glucose accumulation in the thenar eminence in adults: a single-center retrospective study

OBJECTIVE

This study evaluated the frequency, and effect of physiological 2-deoxy-2-[fluorine-18] fluoro-D-glucose (FDG) tracer injection and its association with the penetration rates of mobile devices.

METHODS

This retrospective analysis included 213 patients (mean age ± standard deviation, 66.2 ± 14.1 years; range 23-93 years; 125 men) who underwent FDG-positron emission tomography examination. Elevated FDG activity in the thenar eminence with maximum standardized uptake value (SUVmax) ≥ 2.5 was considered positive. Differences according to age, sex, laterality, and tracer injection side were evaluated using Fisher's exact test. Associations were assessed using Pearson's correlation coefficient.

RESULTS

Twenty-three percent (49/213) of the patients had elevated FDG activity in the thenar eminence (mean SUVmax, 3.50 ± 1.04; range 2.5-6.3), including 18 with bilateral findings. No significant difference existed according to age (< 50 years vs. 50-69 years vs. ≥ 70 years), sex, laterality, or tracer injection side. No significant correlation existed between penetration rates of mobile devices and the findings (p = 0.08).

CONCLUSION

Elevated FDG activity in the thenar eminence occurs in adults, regardless of age, sex, laterality, or tracer injection side. This should be considered a common physiological change that does not warrant any further investigation.

Increased FDG Uptake of the Pectoral Girdle and Serratus Anterior Due to Wallpaper Stripping on PET/CT-Exquisite Demonstration of the Biomechanics

ABSTRACT

According to published guidelines and routine procedures, patients are instructed to avoid strenuous exercise for 6 to 24 hours before FDG imaging, avoiding unfavorable muscular uptake. A 40-year-old man with esophageal carcinoma underwent FDG PET/CT for response assessment. Intense uptake was noted in the muscles of the right upper limb and chest. The patient stated he had avoided exercise before scanning. On further questioning, he was found to be a professional painter and decorator and had been working stripping wallpaper. Marked skeletal FDG uptake occurs in subjects who have strenuously exerted themselves before or after the injection of FDG.

PET/Computed Tomography in the Evaluation of Fever of Unknown Origin and Infectious/Inflammatory Disease in Pediatric Patients

Fever in children is common. If it persists and its cause cannot be identified in a reasonable time, along with laboratory and conventional imaging investigations, it is defined as fever of unknown origin (FUO). 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) is well established in the evaluation of malignancy, which is a possible cause of FUO. FDG often locates inflammatory and infectious lesions considered nonspecific or false-positive for oncology; however, these findings are beneficial in FUO evaluation because infectious and inflammatory diseases are important FUO causes. FDG-PET/CT is being increasingly used for investigation of FUO as well as infectious/inflammatory disease.

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.

Intense Increased 18F-FDG Uptake of Masticator Muscles After Cocaine Use

F-FDG is the most widely used PET tracer worldwide. Before the examination, recommendations are given to patients to avoid muscular activities, with the goal to limit F-FDG uptake in muscles. Here, we report the case of a 36-year-old man with Hodgkin disease referred to our department to perform an F-FDG PET/CT for immunotherapy assessment. The PET images showed a homogeneous, symmetric, and very intense uptake of the masticatory muscles. The medical examination exhibited a trismus, and the patient revealed to have been using cocaine 15 minutes before injection of F-FDG.

Preparation and Logistic Considerations in Performing PET and PET/Computed Tomography in Pediatric Patients

It is good for the nuclear medicine technologist to be aware of the normal variants and the appearance of a good-quality scan. The primary responsibility as a nuclear medicine technologist is to provide an optimal quality scan that maximizes the reading physician's ability to correctly interpret while using current radiation safety practices as the best possible experience is created for patients and families. Combining the radiation safety aspects (nuclear) with how care is provided (medicine) and the use of the most recent equipment (technology) is what defines a nuclear medicine technologist.

Adenocarcinoma of the Stomach Leading to Recurrent Regurgitation and Muscular Hypermetabolism on 18F-FDG PET/CT

Skeletal muscle uptake of F-FDG can result from a variety of physiologic and pathologic conditions. It is important for the physician to interpret these uptake patterns in the correct context to avoid a misdiagnosis. We present a case of a 36-year-old man with progressive, repeated episodes of regurgitation who was diagnosed with adenocarcinoma of the stomach. F-FDG PET/CT showed increased tracer uptake in the primary tumor and in the intercostal and sternocleidomastoid muscles. The pattern of tracer uptake along with the clinical history and examination of the patient helped differentiate a physiologic variant from a pathologic cause.

Intense FDG Uptake in the Muscles Due to Severe Vomiting

A 22-year-old woman with acute lymphoblastic leukemia underwent FDG PET/CT to evaluate possible extramedullary disease. The patient experienced severe nausea and vomiting due to ongoing chemotherapy. The image demonstrated increased FDG uptake in multiple muscle groups, including intercostal, bilateral external oblique, internal oblique, transverse abdominal muscles, and psoas major. One week after the patient stopped vomiting, a repeated PET/CT showed much less muscle uptake.