46 year old man presents with new-onset seizure.
Peripherally hypermetabolic and centrally hypometabolic lesion in the left temporal lobe.
The differential of a peripherally hypermetabolic lesion on PET is similar to that of a ring enhancing lesion, which can be remembered by the pneumonic MAGIC DR L:
M = metastasis *
A = abscess
G = glioblastoma
I = infarct (subacute)
C = contusion
D = demyelinating lesion
R = radiation necrosis, resolving hematoma
L = lymphoma *
* metastasis and lymphoma become extremely unlikely if peripheral FDG uptake is no greater than normal white matter
Brant WE, Helms CA. Fundamentals of diagnostic radiology. Philadelphia: Lippincott Williams & Wilkins, 2012.
Basu S. Nucl Med Commun 2013;34:1237-9.
Intracranial abscess
While a previous MRI had shown a left temporal lesion with thick peripheral enhancement, the repeat study shown above demonstrated a ring enhancing lesion with restricted diffusion (low ADC value) in the center.