MRI: MRA – MRI DTI w/ Tractography

Because detailed images can be acquired from any angle, MRI is excellent in detecting most malignancies and neurological diseases of the brain, spine and pelvis

mri-mra-mri-dti-w-tractography

Magnetic Resonance Imaging (MRI) utilizes a powerful magnetic field to align the magnetization of atoms within the body to produce detailed internal structures. Radio frequency fields are used to systematically alter the alignment of the magnetization. MRI does not emit any ionizing radiation. Procedures involving intravenous contrast use a gadolinium based solution that is very safe to the patient.

Because detailed images can be acquired from any angle, MRI is excellent in detecting most malignancies and neurological diseases of the brain, spine and pelvis. It’s also widely used with sports-related injuries, especially those affecting the knee, shoulder, hip, elbow and wrist. MRI is also resourceful in acute findings such as, Cord Compression, Brain Mass, Brain Fluid Collection, and Fractures.

Magnetic Resonance angiography (MRA) is a special application of Magnetic Resonance technology. It utilizes the same principals as MRI, but instead of focusing on soft tissue and muscles, it focuses on blood vessels. It is often used to evaluate arteries of the neck, brain, aorta, renal arteries, and the legs also known as a “run-off” study.

MRAs can be done with contrast or without contrast just like standard MRIs. With intravenous contrast, images are acquired as the contrast first passes the agent through the arteries. With correct timing, you get high quality images displaying just the arteries themselves allowing for accurate diagnosis for arterial pathologies.

A technique known as time of flight imaging or inflow angiography is possible with MRA. The parameters set on the machine allows the technologist to produce images showing flowing blood to be much brighter than the surrounding stationary tissue What this provides radiologists and referring physicians are high resolution images with focus just on the blood vessels of interest. This technique is most commonly used in head and neck MRAs.

After the scan is complete, the technologist is able to perform post processing techniques to allow radiologists to visualize just the arties without distraction from surrounding tissues. The method is known as maximum intensity projection or MIP where the computer selects the highest signal seen on the scan for display on the screen. The resulting image resembles an image you would see in conventional catheter angiography, procedures commonly done in the hospital.

MR Diffusion Tensor Imaging (DTI) is an application of MRI brain scanning that is becoming widely popular in evaluating the connective fibers and nerves of the brain. In order to perform DTI imaging, the protocol and post processing modules must be purchased from the manufacturing company of respective MRI equipment. Our Siemens’ Magenetom Espree 1.5T is capable of such application.

According to Science Daily, DTI allows radiologists to see areas of the brain rarely ever seen using other imaging modalities. Researchers have reported that diffusion tensor imaging can identify structural change in the white matter of the brain that correlates to cognitive deficits even in patients with mild traumatic brain injury.

What occurs during a DTI protocol is that images are acquired based on the strength (b-value) and direction of a magnetic diffusion gradient, and the local microstructure around the area in which water molecules in the body diffuse. The more attenuated the image is in a particular area, the greater diffusion there is in the direction of the diffusion gradient.

Clinical Indications

  • M.T.B.I – Mild Traumatic Brain Injury
  • T.B.I Traumatic Brain Injury
  • M.S. Multiple Sclerosis
  • C.V.A. Cerebrovascular Accident (Stroke)
  • Septo-Optic Dysplasia
  • Cerebral Ischemia
  • Epileptic Disorder
  • Schizencephaly
  • Agenosis or Corpuscallsum
  • Metabalic Disorders
  • Demyelination R.P.L.S. Reversible
  • Posterior Leukoencepalopathy syndrome
  • Adult and Pediatric Pmyelination
  • Periventricular leukomalacia
  • Brain necrosis
  • General Tumor – Cyst
  • GBM Glioblastoma multiforme
  • Spinal Cord Lesions – demyelinating disease, infraction
  • Vertebral lesion characterization