What are the indications for a cranial Magnetic Resonance Imaging (MRI)?

From the Guidelines

Cranial MRI is indicated for diagnosing and evaluating various neurological conditions affecting the brain and surrounding structures, particularly in cases of unexplained neurological symptoms, suspected stroke, brain tumors, multiple sclerosis, infections, congenital abnormalities, traumatic brain injury, and neurodegenerative disorders.

Indications for Cranial MRI

The following are specific indications for cranial MRI:

• Suspected stroke, where MRI with diffusion-weighted imaging can detect ischemic changes within minutes of onset 1
• Brain tumors, where contrast-enhanced MRI helps identify tumors by highlighting areas with blood-brain barrier disruption 1
• Multiple sclerosis, where MRI can detect demyelinating lesions in the central nervous system
• Infections like encephalitis or meningitis, where MRI can detect inflammation or infection by highlighting areas with blood-brain barrier disruption
• Congenital abnormalities, such as Chiari I deformity, where MRI can detect herniation of the cerebellar tonsils through the foramen magnum
• Traumatic brain injury, where MRI can detect subtle findings adjacent to the calvarium or skull base, such as small cortical contusions and subdural hematomas 1
• Neurodegenerative disorders, such as Alzheimer's disease, where MRI can monitor disease progression and treatment response

Advantages of Cranial MRI

Cranial MRI is preferred over CT scans for brain imaging due to its:

• Superior soft tissue contrast, which allows for better visualization of brain structures
• Ability to visualize structures in multiple planes, which provides a more comprehensive understanding of brain anatomy
• Lack of radiation exposure, which reduces the risk of radiation-induced side effects

Contraindications for Cranial MRI

Cranial MRI is contraindicated in patients with:

• Certain metallic implants, such as pacemakers or aneurysm clips
• Severe claustrophobia, which can make it difficult for the patient to remain still during the examination
• Inability to remain still during the examination, which can result in poor image quality In such cases, alternative imaging modalities, such as CT scans, may be used instead. However, cranial MRI remains the gold standard for diagnosing and evaluating neurological conditions, and its use should be prioritized whenever possible.

From the Research

Indications for Cranial MRI

The following are indications for a cranial Magnetic Resonance Imaging (MRI):

• Exclusion of early disease in the brain due to its greater sensitivity 2
• Evaluation of multiple sclerosis (MS) and other diseases in the periventricular region, such as deep white matter infarcts and interstitial edema caused by hydrocephalus 2
• Detection of small extraaxial fluid collections, particularly in the middle and posterior cranial fossae and at the vertex 2
• Evaluation of the craniovertebral junction, enhanced by the ability to image directly in the sagittal plane 2
• Diagnosis and treatment planning of brain tumors, including differentiation from possible mimics such as metastatic disease, lymphoma, demyelination, and infection 3
• Thrombolytic therapy in patients with acute ischemic stroke, particularly those with minor deficits and low NIH Stroke Scale scores 4, 5
• Assessment of traumatic brain injury, including documentation of intracranial abnormalities for medicolegal reasons and presurgical planning for post-traumatic epilepsy 6
• Early prognostic decision making and prognostic assessment for rehabilitative planning in traumatic brain injury 6

Specific Clinical Settings

In certain clinical settings, MRI is preferred over CT:

• Evaluation of the posterior and middle fossae, where CT is limited by beam-hardening artifact from bone 2
• Detection of hemorrhagic transformation in patients with acute ischemic stroke 4, 5
• Assessment of brain tumors, including initial diagnosis and follow-up after resection and chemoradiation 3

Comparison with CT

While CT is still the examination of choice in several clinical settings, such as:

• Patients on respirators and those with cardiac pacemakers or intracranial aneurysm clips 2
• Trauma victims with fractures and patients with suspected osseous abnormalities of the temporal bones 2
• Acute trauma patients who cannot be sedated and may not be able to lie motionless for the required scan time 2 MRI has several advantages, including greater sensitivity and the ability to image directly in the sagittal plane 2, 5