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Zorluk: ZorOrdering Imaging Studies

A 54-year-old man presents to the emergency department with a 3-day history of severe, progressive mid-back pain, fevers, and new-onset weakness in his legs. His medical history is significant for poorly controlled type 2 diabetes mellitus, intravenous heroin use, and a non-MRI-conditional permanent pacemaker placed 12 years ago for sick sinus syndrome. His temperature is 38.8°C (101.8°F), blood pressure is 115/75 mmHg, pulse is 88/min, and respiratory rate is 16/min. Physical examination reveals focal tenderness to palpation over the T8 spinous process. Neurologic examination shows 3/5 motor strength in the bilateral lower extremities, decreased sensation to pinprick below the umbilicus, and upgoing plantar reflexes bilaterally. Initial laboratory studies show a leukocyte count of 18,000/mm³ and an erythrocyte sedimentation rate of 92 mm/h. Blood cultures are drawn, and empiric intravenous vancomycin and ceftriaxone are initiated. Which of the following is the most appropriate imaging study to order next?

  1. CT myelography of the spineCevap
  2. B
    MRI of the thoracic spine with and without gadolinium
  3. C
    CT of the thoracic spine with intravenous contrast
  4. D
    Plain radiography of the thoracic spine
  5. E
    Positron emission tomography (PET) scan of the spine

Cevap

CT myelography of the spine is the correct diagnostic step for suspected spinal cord compression when MRI is contraindicated.
The correct answer is CT myelography. This patient presents with signs of an acute spinal epidural abscess (SEA) causing spinal cord compression, indicated by back pain, fever, and neurologic deficits in the setting of IV drug use. The gold standard imaging modality for suspected SEA is an MRI of the spine with and without gadolinium. However, this patient has a non-MRI-conditional permanent pacemaker, which is an absolute contraindication to MRI. When MRI cannot be performed, CT myelography is the diagnostic imaging test of choice because the intrathecal contrast allows for clear visualization of the spinal canal, subarachnoid space, and any extradural compression.

Adım Adım Çözüm

1
Analyze the patient's clinical presentation.
The patient has the classic triad of fever, focal back pain, and neurologic deficits (weakness, sensory level, upper motor neuron signs) highly suggestive of a spinal epidural abscess causing acute spinal cord compression.
Identifying the suspected diagnosis dictates the required diagnostic imaging and timeline (emergent).
2
Determine the gold standard imaging modality for the suspected diagnosis.
MRI of the spine with and without gadolinium contrast is the standard of care for diagnosing a spinal epidural abscess.
MRI provides the best soft-tissue resolution of the spinal canal, epidural space, and spinal cord.
3
Review the patient's medical history for contraindications to the standard imaging.
The patient has a non-MRI-conditional permanent pacemaker placed 12 years ago.
Subjecting this patient to an MRI could result in life-threatening pacemaker malfunction, heating of the leads, or dislodgment.
4
Select the most appropriate alternative imaging study based on evidence-based guidelines.
CT myelography of the spine is selected.
Intrathecal contrast used in myelography combined with CT imaging allows for clear visualization of the spinal canal, subarachnoid space, and any extradural compression by an abscess, making it the best alternative to MRI.

Anahtar Kavram

In patients presenting with suspected acute spinal cord compression (e.g., spinal epidural abscess) who have an absolute contraindication to MRI (such as a non-MRI-conditional pacemaker), CT myelography is the diagnostic imaging study of choice.
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Ordering Imaging Studies

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