NM artefacts


Technical issues

  • Injection site will cause high radiotracer activity
  • Extravasation of injection causes uptake in lymph nodes

Equipment malfunction

  • Malfunction of gamma camera system
    • Photomultiplier tube (PMT) failure
    • Cracked or broken scintillation crystal
    • Correction matrix failure
    • Cracked crystal
    • Differences in detector sensitivity

Patient related

  • Attenuation can be caused by:
    • Objects worn by the patient e.g. belt buckles
    • Breast attenuation especially breast prosthesis
    • Diaphragmatic attenuation: especially in patients that are obese, have ascites, on dialysis
  • Patient motion causes misalignment of reconstructed images
  • Urinary contamination

Physiological uptake

  • Head and neck
    • Brain cortex
    • Waldeyer's ring
    • Salivary glands
    • Extra-ocular muslces
    • Larynx in excessive talking
  • Muscles
    • Stress-induced tension - trapezius and paraspinal muscles
    • Hyperventilation - diaphragm
    • Insulin - skeletal muscle
    • Vigorous exercise
  • GIT / GUT
    • Caecum / right colon more glucose avid
    • Renal collecting system, ureters and bladder
    • Uterine uptake in menstruation
  • Miscellaneous
    • Lactating breasts
    • Myocardial uptake post-prandially
    • Brown fat
    • Thymus in children

SPECT and PET/CT specific

  • Centre-of-rotation error
    • In SPECT, if presumed centre-of-rotation doesn't match actual axis of rotation back-projection will be affected
  • Misregistration between radionuclide and CT images
  • All CT related artefacts
  • Truncation
    • SPECT field of view is larger than CT field of view
    • No CT data available for attenuation correction of the SPECT images

 

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