INTERESTING IMAGE

Unilateral Diffusely Increased Muscle Uptake of F-18 FDG in a
Patient With Hemiparesis Due to Stroke
Pushpender Gupta, MD,* Gopi Kota, MD,* Abass Alavi, MD,† and Akiva Mintz, MD, PhD*‡

Abstract: Although normal muscles accumulate less F-18 fluorodeoxyglucose (FDG) under normoglycemic conditions, FDG muscle uptake is frequently encountered on PET scans. However, diffusely elevated unilateral
muscle uptake is not frequently seen. In this report, we demonstrate a case of
unilateral muscle uptake in a patient with a remote history of stroke, possibly
explained by increased spasticity, a shift toward fast twitch (type II) muscle
fibers, and inflammatory changes that are all seen post– upper motor neuron
injury. Thus, FDG PET may serve as a functional biomarker of the extent of
upper motor neuron injury after stroke.
Key Words: PET/CT, hemiparesis, upper motor neuron injury, F-18 FDG
uptake
(Clin Nucl Med 2011;36: 1140 –1141)
Received for publication March 13, 2011; revision accepted June 27, 2011.
From the *Department of Radiology, Wake Forest University Baptist Medical
Center, Winston-Salem, NC; †Division of Nuclear Medicine, Department of
Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA; and
‡Department of Neurosurgery, Wake Forest University Baptist Medical Center, Winston-Salem, NC.
Conflicts of interest and sources of funding: none declared.
Reprints: Akiva Mintz, MD, PhD, Departments of Radiology and Neurosurgery,
Wake Forest University Health Sciences, Medical Center Blvd., WinstonSalem, NC 27157. E-mail: amintz@wfubmc.edu.
Copyright © 2011 by Lippincott Williams & Wilkins
ISSN: 0363-9762/11/3612-1140

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Clinical Nuclear Medicine • Volume 36, Number 12, December 2011

Clinical Nuclear Medicine • Volume 36, Number 12, December 2011

Increased Muscle Uptake of F-18 FDG in Hemiparesis

FIGURE 1. A 63-year-old man was referred to our department of nuclear medicine for staging evaluation of recurrent squamous
cell carcinoma. The patient additionally had a remote history significant for stroke (20 years ago) that resulted in right-sided
hemiparesis. Neurologic examination revealed motor strength of 1/5 in the right upper and lower extremities and 5/5 in the left
upper and lower extremities with intact sensations throughout. In addition to the known malignancy in the base of the tongue
region (A, arrowhead), the PET/CT scan revealed diffusely increased tracer uptake in muscles of the right chest wall, right shoulder,
right upper extremity, and right lower extremity (A–C, arrows). The PET/CT images of the brain revealed a photopenic area
involving the left lentiform nucleus along with decreased tracer uptake in left thalamus (D–E, arrows). Physiologic muscle uptake
can be attributed to a number of factors that may occur around the time of injection, including increased insulin, surgical
interventions, voluntary activities (talking, chewing, exercising), and involuntary muscle activity (labored breathing, coughing,
stress-induced muscle spasm). Although normal muscle uptake is typically symmetric or limited to single muscle or functional
group, our case illustrates the interesting findings on an FDG PET scan of relatively preserved muscle mass but diffusely increased
unilateral muscle glucose metabolism in a patient with upper motor neuron injury nearly 20 years after a stroke. These findings of
increased FDG muscle uptake in a hemiparetic patient indicate a potential role of using FDG PET for in vivo noninvasive assessment
of muscle changes after a stroke and potential changes in uptake pattern in response to physical rehabilitation. Stroke is the leading
cause of disability in the United States. Hafer-Macko et al have proposed that in addition to the primary brain injury, the disability in
stroke patients may also be because of secondary biologic abnormalities of muscle atrophy, altered contractile protein expression
with a shift toward fast twitch fibers, and skeletal muscle inflammation. Thus, FDG PET may serve as a functional biomarker of the
quantity and extent of muscle changes after stroke and possibly to monitor effects of intervention.1– 8

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