Advanced MRI techniques focusing on the function and fine structure of the brain offer insights that typical structural MRI studies cannot.
Despite decades of development of advanced MRI techniques in universities worldwide, surprisingly few patients currently benefit from advanced MRI techniques to diagnose and guide therapies. This suite of imaging technologies offer information about the brain and its function that compliments the physician’s evaluation and standard diagnostic tests.
Functional MRI (fMRI) is a technique to measure activity throughout the brain. In a healthy individual, brain regions involved with language, memory, movement, and other cognitive function can be accurately identified. In a patient with abnormal brain function, such as tumor, concussion, memory loss, psychiatric disease, or encephalopathy, abnormalities in these activation patterns can be detected. Of particular interest, these activation patterns along with blood flow pattern changes can provide the neurosurgeon with important information in regards to the precise location of a tumor and its potential spread.
Arterial spin labeling MRI (ASL) provides information about blood perfusion throughout the brain without the ionizing radiation associated with PET or SPECT scans and with superior spatial resolution. Abnormal patterns of perfusion have been know to occur in psychiatric disorders such as anxiety, depression and obsessive-compulsive disorder, and ASL perfusion can be used to guide the treatment and diagnosis of patients with these conditions. Moreover, ASL is used to diagnose and guide treatment of concussion and brain injury, infectious encephalopathy such as Lyme-related encephalopathy, and as an aid for neurosurgical planning.
Resting state MRI (rsMRI) identifies brain networks that make up the backbone of normal brain function. Often abnormalities in these networks are the earliest objective findings in patients with memory loss conditions. Whereas in the healthy brain these networks show balanced activity, abnormal network size and activity can be seen in patients with chronic pain conditions, memory loss, and psychiatric disease.
Other advanced MRI techniques in clinical use at the Pacific Neuroscience Institute include diffusion tensor imaging (DTI) MRI, quantitative structural MRI, and MRI spectroscopy. DTI MRI, or tractography, allows for the identification and measurement of microscopic-level brain connectivity, and these measurements can be key in selecting surgical plan for tumor resection, diagnosis of normal pressure hydrocephalus, and in the diagnosis of traumatic brain injury. Quantitative structural MRI uses computer algorithms to measure the size and volume of brain regions, and memory loss diagnoses can be clarified by comparing these measurements to a large database of control subjects. MRI spectroscopy allows for the measurement of microscopic levels of metabolites and neurotransmitters, and this data can be indispensable for characterizing types of brain tumors and aiding the diagnosis of memory loss conditions, brain injury and encephalopathy.