Lecture Notes on Diagnostic Imaging Tests

Introduction

• Discussion on various diagnostic imaging tests used in medical practice.
• Focus on CAT scans, CT angiography, MRI, PET scans, lumbar punctures, EMG, angiograms, EEG, and carotid Doppler studies.

CAT Scan (Computerized Axial Tomography)

• Uses a narrow x-ray beam for cross-sectional images.
• Helps evaluate, differentiate, and follow up on cranial abnormalities.
• Differentiates well for vascular and small lesions.
• Types: Unenhanced (without contrast) and Enhanced (with contrast).
• Nursing Considerations:
  • Client must lie still.
  • Assess iodine or contrast allergies.
  • Written consent required for enhanced scans.
• Examples:
  • Image of an epidural hematoma.
  • Image of a brain tumor.

CT Angiography (CTA)

• Combines high-tech rotating machine and contrast dye.
• Evaluates blood vessels of the brain, heart, lungs, and kidneys.
• Detects aneurysms and narrowed vessels.
• Nursing Considerations:
  • Screen kidney function (BUN and creatinine).
  • Check for allergies to contrast material.

MRI (Magnetic Resonance Imaging)

• Uses magnetic fields and radio frequency signals.
• Provides clear images of soft tissues early on.
• Nursing Considerations:
  • Client must lie still and wear earplugs due to noise.
  • Screen for ferromagnetic substances (implanted devices, pacemakers).
  • Assess for the need for sedation.
• Can be done with or without contrast dye.

PET Scan (Positron Emission Tomography)

• Shows metabolic function through radioactive substances.
• Combines with MRI for 3D images of brain activity.
• Identifies areas of increased activity in the brain.

Lumbar Puncture (LP)

• Measures cerebrospinal fluid (CSF) pressure and samples.
• Diagnoses disorders like meningitis and subarachnoid hemorrhage.
• Nursing Considerations:
  • Client should lie flat post-procedure to prevent CSF leakage and headache.
  • Monitor vital signs and neurological function.
  • Encourage fluid intake.
  • Look out for complications like infection.

Electromyography (EMG)

• Measures electrical activity in muscles.
• Diagnoses neuromuscular diseases.
• Uses electrodes inserted into muscles.

Angiogram

• Similar to coronary angiogram, focusing on cranial vessels.
• Uses catheter and contrast dye.
• Nursing Considerations:
  • Obtain informed consent.
  • Assess for iodine or contrast allergies.
  • Check renal function (BUN and creatinine).
  • Monitor neurological status post-procedure.

EEG (Electroencephalography)

• Measures electrical impulses in the brain.
• Diagnoses seizures, brain tumors, sleep disorders.
• Non-invasive with sticky electrodes on the scalp.

Carotid Doppler Studies

• Ultrasound of carotid arteries for blood flow.
• Identifies stenosis and occlusions.
• Non-invasive and painless.