Imaging Guidelines for Evaluating Brain Injuries and Connections

Recommended Imaging Modalities

The American College of Radiology recommends MRI brain without and with IV contrast for evaluating connections in the brain, as it provides superior anatomical detail and soft tissue contrast necessary for visualizing neural pathways and connections, with a rating of 9/9 according to ACR guidelines 1, 2
MRI brain without and with IV contrast allows visualization of neural pathways and connections, provides superior soft tissue contrast and anatomical detail, and contrast enhancement helps identify vascular structures and abnormalities 1, 2
For acute head trauma, CT without contrast is the first-line imaging modality due to its speed, accessibility, and ability to detect acute hemorrhage, as recommended by the American College of Radiology 3

High-field strength magnets (3T preferred over 1.5T) provide better resolution for small structures like the ventral tegmental area, and thin-slice acquisition (≤1mm) is recommended for detailed visualization 4
Isotropic 3D T1-weighted sequences allow for multiplanar reconstruction and volumetric analysis, and a minimum delay time of 5 minutes is recommended between gadolinium injection and T1-weighted sequence acquisition 4
Single dose contrast (0.1 mmol/kg body weight) is typically sufficient, and inadequate spatial resolution may miss small neural connections 4

If MRI is contraindicated or unavailable, CT head without IV contrast (rating 8/9) may be used, which is less sensitive for neural pathway visualization but better for detecting calcifications and bony abnormalities 1, 5
CTA head with IV contrast (rating 8/9) may be used for vascular assessment, but is less effective for neural pathway evaluation 1
MR angiography (MRA) head without and with contrast (rating 8/9) may be combined with MRI brain without and with contrast for comprehensive evaluation of both brain parenchyma and vascular structures 1

Follow-up imaging intervals should be determined based on the clinical context and initial findings, and for stable conditions, follow-up imaging every 12-24 months may be appropriate 1, 6
Proper patient preparation is essential to minimize motion artifacts, and suboptimal repositioning during follow-up imaging can produce artifacts that mimic changes in neural structures 4
For subacute head trauma (>72 hours), MRI is more sensitive for detecting small cortical contusions, subdural hematomas, diffuse axonal injury, and non-hemorrhagic axonal injury 3, 6

The American College of Radiology recommends the following MRI sequences for evaluation of subacute or chronic head trauma:

Sequence	Description
T1-weighted imaging	Detects anatomy and structural abnormalities
T2-weighted imaging	Detects edema and inflammation
T2*-weighted/gradient echo sequences	Detects hemorrhage and calcifications
Diffusion-weighted imaging	Detects acute ischemia and infarction
FLAIR sequences	Detects subacute and chronic ischemia, and inflammation [3]

For new-onset seizures without trauma, MRI is preferred due to its higher sensitivity for small lesions 5
For refractory seizures, MRI with specific epilepsy protocols is recommended 5
For new-onset focal neurological deficits, such as left-sided weakness, MRI is strongly recommended over CT for detecting subacute brain injuries, according to the American College of Radiology 3, 6
For worsening symptoms without focal deficits, consider MRI if symptoms are progressive or persistent, according to the American College of Radiology Appropriateness Criteria 6
For stable symptoms without new deficits, clinical follow-up may be sufficient without additional imaging, as stated by the American College of Radiology Appropriateness Criteria 6