Focal Inflammatory Myositis on 18F-FDG PET/CT

Elevated 68 Ga-FAPI Activity in Pulmonary Inflammatory Pseudotumor

ABSTRACT

We present a case of pulmonary inflammatory pseudotumor with elevated 68 Ga-FAPI activity. Our case suggested that pulmonary inflammatory pseudotumor should be considered in the differential diagnosis of cancer-like solitary pulmonary nodules with increased 68 Ga-FAPI uptake.

Acute Findings on FDG PET/CT: Key Imaging Features and How to Differentiate Them from Malignancy

PURPOSE OF REVIEW

To review acute findings commonly encountered during routine clinical FDG PET/CT studies and present key imaging features to differentiate them from malignant counterparts.

RECENT FINDINGS

FDG PET/CT is extensively used in routine clinical practice for oncology patients. Incidental acute findings in patients undergoing FDG PET/CT are increasingly common, and awareness of these findings and their mimics are important in delivering a clinically relevant and accurate radiological report for directing further management.

SUMMARY

This article will review examples of common acute findings encountered during routine FDG PET/CT scans, compare them against examples of FDG-avid malignancy that can mimic these findings and emphasize key imaging findings to differentiate acute findings from their malignant mimics.

PET Scan: Nuclear Medicine Imaging in Myositis

PURPOSE OF REVIEW

Positron emission tomography (PET) combined with computed tomography (CT) has proven useful as a cancer screening technique in patients with inflammatory myopathy, mainly dermatomyositis. In this review, we focus on advances in this direction and other potential applications of PET/CT in patients with inflammatory myopathy.

RECENT FINDINGS

Cancer screening by PET/CT seems suitable and cost-effective in patients with myositis. It has also shown value as a hybrid technique for diagnosing myositis versus controls and could be of interest for differentiating between polymyositis and sporadic inclusion body myositis. Quantification of muscle activity by PET/CT seems reliable. Preliminary data suggest that it could also be used to diagnose and measure the activity of the disease in the lung. PET/CT should be in the toolbox of physicians managing patients with myositis. The multiple applications of PET/CT include its value for cancer screening, measuring the activity of the disease in muscle, and helping to differentiate between myositis phenotypes. The possibility to diagnose and monitor inflammatory lung activity remains to be demonstrated in well-designed studies.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.

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

It is common to notice increased FDG activity in the muscles of the forearms or hands on PET/CT images. The purpose of this study was to determine relationship between the prevalence of increased FDG activity in the forearms or hands and using mobile devices prior to the FDG PET/CT study.

METHODS

A total of 443 young patients with ages between 5 and 19 years who underwent FDG PET/CT scan were included in this retrospective analysis. All patients had FDG PET/CT with their arms within the field of views. The images were reviewed for elevated activity in the muscles of the distal upper extremities (DUEs), which include forearms and hands. The preimaging questionnaire/interview records regarding using mobile devices prior to FDG PET/CT were also reviewed and compared with the imaging findings.

RESULTS

Most patients (72.0% [319/443]) used mobile devices more than 60 minutes in the period of 24 hours prior to the FDG PET/CT study. Elevated uptake in the muscles in the DUEs was observed in 38.6% (123/319) of these patients. In contrast, among 124 patients who did not use the mobile devices or used the mobile device minimally prior to the study, only 6.5% (8/124) of them had elevated FDG activity in the DUEs. The difference persisted following stratification analysis for sex, age, and serum glucose level in our patient population.

CONCLUSIONS

Increased FDG uptake in the muscles of the DUEs in young patients is commonly seen in those who used mobile devices prior to PET/CT study. Recommendation should be considered to reduce using mobile devices prior to FDG PET/CT study in young patient population.

Myositis in the head and neck: challenges in diagnosis and management

Myositis in the head and neck may present with non-specific symptoms, and radiographically may mimic malignancy. Multidisciplinary management is often essential, and we describe the challenges in an effort to raise awareness of the condition.