Table 4.

Commonly used imaging technologies for brain cancer management

Imaging Technology	Magnetic Resonance Imaging (MRI)	Computed Tomography (CT)	Positron Emission Tomography (PET)	Ultrasound (US)
Mechanism	Main diagnostic approach for brain cancers. MRI employs a strong magnetic field to force protons of water molecules in the body to align with the field, and the scanner can detect the changes in the direction and rotational axis of protons and the energy released.	CT uses X-ray to generate detailed scans of the areas in the body.	PET uses radiotracer to assess the functions of the tissue or organ, such as blood flow, oxygen or glucose consumption.	Ultrasound utilizes high frequency (> 20 kHz) sound waves to produce biological images and the image is produced based on the reflection of the waves off the body structures.
Strength	Fast, noninvasive, nonradioactive and good spatial resolution.	Fast (minutes ~ half an hour); noninvasive; images can be visualized in 2-D (slice) or 3-D fashion.	Often be used in combination with CT to provide accurate anatomic information.	Non-radioactive and quite versatile; for instance, focused ultrasound (FUS) has been adapted for BBB disruption for drug delivery, treatment of neurodegenerative and cerebrovascular diseases, and neurosurgical small volume tumor ablation [32, 141].
Limitation	Contrast enhancing agent, such as gadolinium has high renal toxicity.	Radiation from X-ray; lack of anatomic information.	Radioactive tracers.	Limited spatial resolution.