70551

Magnetic resonance (eg, proton) imaging, brain (including brainstem); without contrast material

CPT code 70551 refers to a diagnostic Magnetic Resonance Imaging (MRI) of the brain and brainstem performed without the administration of intravenous contrast material. MRI is a sophisticated, non-invasive imaging modality that utilizes a powerful static magnetic field and radiofrequency pulses to generate high-resolution, multi-planar images of the central nervous system. Unlike computed tomography (CT), MRI does not utilize ionizing radiation; instead, it relies on the magnetic properties of hydrogen protons within the body's water and fat molecules. When placed in the scanner, these protons align with the magnetic field. Radiofrequency pulses are applied to tip these protons out of alignment, and as they return to their baseline state (relaxation), they emit energy captured by receiver coils. This energy is processed by a computer using complex mathematical algorithms, such as the Fourier transform, to create detailed anatomical images. The 'without contrast' designation means that no gadolinium-based contrast agent is injected during the session. This specific protocol is essential for evaluating the structural integrity of the cerebrum, cerebellum, and brainstem. It is particularly effective for identifying acute ischemic strokes via diffusion-weighted imaging (DWI), detecting structural malformations, assessing for hydrocephalus, and monitoring neurodegenerative conditions like Alzheimer's disease or multiple sclerosis. In many clinical scenarios, 70551 serves as the baseline study for neurological complaints, providing superior soft-tissue contrast that allows for clear differentiation between gray matter, white matter, and cerebrospinal fluid without the risks associated with contrast media in patients with renal impairment.

Clinical Indications

  • Evaluation of acute or chronic headaches with red-flag symptoms
  • Assessment of suspected ischemic or hemorrhagic stroke
  • Investigation of seizure disorders or new-onset epilepsy
  • Evaluation of cognitive decline, dementia, or memory loss
  • Screening for structural abnormalities or congenital brain malformations
  • Monitoring of known intracranial lesions or tumors
  • Assessment of traumatic brain injury (TBI) and post-concussive syndrome
  • Evaluation of central nervous system infections (e.g., meningitis, encephalitis)
  • Investigation of cranial nerve abnormalities or palsies
  • Workup for unexplained vertigo, ataxia, or gait disturbances
  • Evaluation of pituitary gland disorders
  • Assessment of multiple sclerosis or other demyelinating diseases

Procedure Steps

  1. Verify patient identity and perform rigorous MRI safety screening for metallic implants, pacemakers, or foreign bodies.
  2. The patient is instructed to change into MRI-safe attire and remove all jewelry or external metallic objects.
  3. The patient is positioned supine on the MRI gantry table with the head secured in a dedicated multi-channel head coil.
  4. Hearing protection is provided to the patient to mitigate noise from the gradient coils.
  5. The patient is moved into the center of the magnetic bore.
  6. Localizer or 'scout' sequences are obtained in three planes to define the anatomical boundaries of the scan.
  7. Standard pulse sequences are acquired, including T1-weighted, T2-weighted, and Fluid-Attenuated Inversion Recovery (FLAIR) sequences.
  8. Diffusion-weighted imaging (DWI) and Apparent Diffusion Coefficient (ADC) maps are acquired to assess for acute cellular edema/ischemia.
  9. Susceptibility-weighted imaging (SWI) or Gradient Echo (GRE) sequences may be included to detect hemorrhage or mineralization.
  10. The technologist monitors the images for motion artifacts and repeats sequences if necessary for diagnostic quality.
  11. Upon completion, images are transferred to the Picture Archiving and Communication System (PACS) for radiologist interpretation.

Coding Guidelines

  • Do not report 70551 in conjunction with 70552 (with contrast) or 70553 (without followed by with contrast) for the same anatomical site during the same session.
  • If the MRI brain is performed with an MRI of the orbits, face, or neck, ensure that separate medical necessity exists for each distinct area to support multiple coding.
  • Append modifier 26 (Professional Component) if only the physician interpretation and report are being billed.
  • Append modifier TC (Technical Component) if only the use of the equipment, supplies, and technical staff is being billed.
  • For facilities or practices billing globally (both technical and professional), no modifier is required.
  • CPT 70551 includes the brainstem; do not code separately for posterior fossa or brainstem imaging.
  • If a procedure begins as 'without contrast' but the radiologist determines contrast is needed, code only 70553 (without followed by with contrast).

Associated ICD-10 Codes