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Congress: ECR25
Poster Number: C-14461
Type: Poster: EPOS Radiologist (educational)
Authorblock: M. Hovsepian, J. San Roman, C. Collaud, G. B. Amorin, N. Pabstleben; Buenos Aires/AR
Disclosures:
Magali Hovsepian: Nothing to disclose
Jose San Roman: Nothing to disclose
Carlos Collaud: Nothing to disclose
Gabriela Beatriz Amorin: Nothing to disclose
Nadia Pabstleben: Nothing to disclose
Keywords: Hybrid Imaging, Molecular imaging, Neuroradiology brain, PET-CT, Molecular imaging, Dementia, Motility
Findings and procedure details
  • Brain 18F-DOPA PET scan shows in vivo the nigrostriatal dopaminergic system.
  • The physiological biodistribution pattern of 18F-DOPA in the body includes high uptake in basal ganglia, pancreas, adrenal glands, and excretion in urinary and biliary tracts.
    Fig 6: 18F-DOPA physiologic uptake and normal biodistribution. A) Whole body PET scan showing the normal biodistribution of 18F-DOPA in the body. Normal radiotracer uptake is seen in basal ganglia, liver, spleen and pancreas. Tracer excretion is seen in the urinary and biliary tracts. B) Focusing on the normal biodistribution of 18F-DOPA in the brain, the basal ganglia are normally visualized, mainly striatum (including caudate and putamen nuclei) while amygdala and thalamus show a minimal or negligible uptake of the tracer.
  • Normal striatum uptake has a typical “comma” shape and is symmetrical.
  • In PD patients, 18F-DOPA PET shows a characteristic pattern of striatal decrease uptake from the back to the front, first losing the “tail” of the “comma”. This pattern is not present in other PS and is used to differentiate both conditions. [1, 4, 5]
    Fig 7: Male patient of 46 y/o, with involuntary tremors and muscular stiffness in right upper and lower limb. Refers loss of sense of smell (anosmia) which started more than 10 years ago. Normal electromyography. Mild cognitive impairment. Brain 18F-DOPA PET scan shows decreased tracer uptake in left putamen (red arrows) and to a lesser extent in the left caudate nucleus (yellow arrow), reflecting dopamine pathway deficiency, compatible with early onset Parkinson's disease. Right striatum with normal typical “comma shape” uptake. A) PET images. B) CT images. C) Fused PET-CT images.
  • The decreased uptake may be symmetrical or asymmetrical.
    Fig 8: Male patient (41 y/o). Stiffness and slowness in movements with the upper and lower limbs on the left side, associated with tremors in the left arm. Clinical suspicion of Parkinson's disease. Asymmetric decrease in 18F-DOPA uptake in both striatal nuclei (red arrows), particularly affecting the putamen with right predominance, representing involvement of the nigrostriatal pathway.
    The abnormal striatal uptake is contralateral to motor symptoms. [1, 4, 5]
    Fig 9: Female patient (50 y/o), with stiffness and resting tremor in the right arm of 2 years' duration associated with bradykinesia. Diagnostic suspicion of Parkinson's disease. Brain 18F-DOPA PET scan shows decreased tracer uptake in the left putamen (red arrow), expressing presynaptic dopaminergic deficit of the nigrostriatal pathway, characteristic of PD.
    Fig 10: Male patient (35 y/o), with tremor in the index finger of the left hand for 6 months and slow reaction of the left upper limb. Previous MRI without significant findings. 18F-DOPA PET images show asymmetry of radiotracer uptake in the striatum, due to a marked decrease in fixation at the right putamen (red arrow), compatible with presynaptic dopaminergic deficit of the nigrostriatal pathway on the right side, consistent with PD.
  • 18F-DOPA PET images can be fused with CT or MRI images (PET/MRI), adding anatomical detail to the evaluation.
    Fig 11: Fig 11A Female patient (75 y/o), with anosmia, bradykinesia, mild resting tremor in the right arm and cognitive impairment. Currently on levodopa treatment, with improvement of motor symptoms. Brain 18F-DOPA PET scan shows decreased radiotracer uptake in both striatum nuclei (arrows), with a more evident reduction at the putaminal level with left predominance (red arrows), suggestive of a presynaptic dopaminergic deficit in the nigrostriatal pathway.
    Fig 112: Fig 11B Female patient (75 y/o), with anosmia, bradykinesia, mild resting tremor in the right arm and cognitive impairment. Currently on levodopa treatment, with improvement of motor symptoms. Brain 18F-FDG PET scan shows decreased metabolism in the temporal and parietal lobes (red arrows), with left predominance. To a lesser extent, a slight decrease in cortical metabolism is observed in the frontal regions. MRI shows mesial temporal lobe atrophy with slight decrease in bilateral hippocampal volume (MTA 2) (yellow circle), with reduced metabolism evident in PET images. PET/MRI reflects cortical involvement with AD-type neurodegenerative pattern.

  • Diagnostic procedure

    • Patient preparation includes solid food fasting for six hours before examination. Adequate hydration is recommended. [2]
    • 24 hours before PET scan, patient treatment with L-DOPA or other anti-parkinsonian drugs should be suspended.
    • Pretreatment with 200 mg of carbidopa orally (peripheral dopa decarboxylase inhibitor) 60 minutes before radiotracer injection is routinely indicated. It is a common practice that increases the availability of DOPA to the brain and reduces the absorbed dose to the bladder and kidneys.
    • IV injection of 5 mCi of 18F-DOPA is the usual dose in adult patients.
    • PET image acquisition should start between 70-90 minutes post radiotracer IV injection. [2]
    • Patients should be in supine position, head first in a dedicated holder and arms along the body. Movements during the examination should be avoided. PET scans must include the whole head.
GALLERY