Case Author(s): Stephen Schmitter, M.D. and Tom R. Miller, M.D., Ph.D. , 5/27/01 . Rating: #D2, #Q4

Diagnosis: Pericarditis

Brief history:

84 year-old woman with progressive shortness of breath and lower extremity edema

Images:

Anterior FDG-PET Projection Image

View main image(pt) in a separate image viewer

View second image(pt). Coronal and Axial FDG-PET Images

View third image(ct). Axial Computed Tomography Images Obtained Six Days Prior to FDG-PET Exam

View fourth image(ct). Axial Computed Tomography Images

Full history/Diagnosis is available below

Diagnosis: Pericarditis

Full history:

84 year-old woman with a history of congestive heart failure who presents with worsening dyspnea on exertion and lower extremity edema. Initial work-up revealed bilateral pleural effusions and a hemorrhagic pericardial effusion. PET is requested to evaluate for possible underlying malignancy.

Radiopharmaceutical:

14.9 mCi F-18 Fluorodeoxyglucose intravenously

Findings:

Projection (main image), coronal and axial (second image) FDG-PET images demonstrate marked hypermetabolism surrounding the heart in the region of the pericardium. A nodular area of increased uptake is also seen in the expected position of the lower pole of the right lobe of the thyroid gland.

Axial computed tomographic images (third image) reveal a large pericardial effusion with some thickening and mild enhancement of the pericardium inferiorly.

Axial computed tomographic images (fourth image) through the upper chest demonstrate enlargement and heterogeneous enhancement of the lower pole of the right lobe of the thyroid, corresponding to the FDG-PET abnormality.

Discussion:

FDG-PET has been shown to be useful in the evaluation of a number of malignancies. One of the well-recognized pitfalls in this application is uptake in inflammatory processes. Recently, there has been increased interest in taking advantage of this uptake by using FDG-PET to image sites of suspected inflammation. There are a number of reasons for increased FDG uptake at sites of inflammation, including: significantly increased glucose utilization by activated neutrophils and macrophages, overexpression of a high affinity glucose transporter, greater reliance on glycolysis (more glucose used per ATP molecule produced), uptake by dividing fibroblasts and activated endothelial cells, and probably uptake within microorganisms.

One study looking at the use of FDG-PET in suspected soft tissue or osseous infection yielded a sensitivity of 98% and specificity of 75%. Advantages of FDG-PET over other scintigraphic modalities include: rapid diagnosis (2 hours vs. 24-72 hours with Ga-67 or labeled leukocytes), better spatial resolution, the fact that cell-labelling is not required, the ability to evaluate structures that have increased uptake normally on other modalities (eg. liver and spleen), the fact that uptake is less influenced by altered marrow distribution, and the ability to use semiquantitative evaluation. In this case, the inflammatory uptake was noted incidentally.

Incidental thyroid uptake is not infrequently seen on FDG-PET imaging. Often the uptake is diffuse. This can be seen normally or with more significant uptake, in chronic thyroiditis. Occasionally, this can be seen in malignancy, such as lymphoma, so clinical correlation is important. With focal uptake, possibilities include thyroid carcinoma or adenoma. Because experience with focal thyroid uptake is limited, our practice is to recommend thyroid sonography and possible biopsy for further evaluation.

References: Stumpe K et al., Eur J Nucl Med 2000;27:822-832.

Yasuda S et al., Radiology 1998;207:775-778.

Followup:

Work-up for malignancy was negative. No malignant cells or microorganisms were noted in pericardial or pleural fluid. Only inflammatory cells were identified. A more invasive evaluation was not performed secondary to the patient's very poor functional status and her pericardial abnormality was presumed to be inflammatory.

The patient underwent ultrasound-guided needle biopsy of the lesion in the right lobe of the thyroid. This demonstrated only hyperplasia.

ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Heart and Great Vessels, Category:Inflammation,Infection)

Search for similar cases.

Edit this case

Add comments about this case

Read comments about this case

Return to the Teaching File home page.

Case number: pt061

Copyright by Wash U MO