Magnetic Resonance Imaging (MRI) is a powerful diagnostic tool that uses a strong magnetic field and radio waves to create detailed, cross-sectional images of your internal organs and tissues. These scans provide physicians with a comprehensive view of anatomy, which is often necessary to diagnose injuries, disease, or other abnormalities. While the resulting images and the accompanying radiology report contain a wealth of information, the specialized language can feel impenetrable to the average person. This guide aims to help you navigate the complex terminology and standardized structure of your MRI report.
MRI Technology and Image Types
The images produced by an MRI machine are the result of manipulating the hydrogen atoms within the body’s water and fat molecules. The scanner temporarily aligns these atoms using a powerful magnet and then uses radiofrequency pulses to knock them out of alignment. As the atoms return to their original state, they emit signals that the scanner detects and converts into images.
The contrast and appearance of tissues depend on the specific timing parameters used, leading to different image sequences. The two most common are T1-weighted and T2-weighted images, designed to highlight different tissue characteristics. T1-weighted images depict anatomical structures well; fat appears bright (high signal intensity) and fluid appears dark. Conversely, T2-weighted images are sensitive to pathology, as tissues with high water content, such as fluid, edema, or inflammation, appear bright.
A specialized T2 sequence, Fluid Attenuated Inversion Recovery (FLAIR), is frequently used in brain imaging. FLAIR intentionally suppresses the bright signal from cerebrospinal fluid (CSF), making it appear dark. This allows lesions or areas of inflammation near the CSF-filled ventricles to be seen more clearly. By comparing tissues across these various sequences, radiologists determine the composition of an abnormality, such as whether it is a fluid-filled cyst or a solid mass.
Structure of the Official MRI Report
The official document is a standardized communication from the radiologist to the requesting physician. The report typically begins with the Clinical History or Indication, outlining the patient’s symptoms or the specific question the referring physician wants the MRI to answer. This section provides context for the radiologist’s interpretation.
Following this is the Technique section, which describes the equipment and methods used, such as whether the scan was performed with or without intravenous contrast dye. The core of the document is the Findings section, where the radiologist provides a detailed, objective description of every structure examined. This may include specific measurements, comparisons to previous scans, and descriptions of both normal and abnormal observations.
The final section is the Impression or Conclusion. This is the radiologist’s summary, which distills the technical findings into a concise interpretation of the most significant observations. The impression directly addresses the clinical question posed in the history and often suggests a potential diagnosis or further steps, guiding the referring physician’s next actions.
Translating Common Medical Terminology
The language of the Findings section relies heavily on terms related to signal intensity, which describes how bright or dark a tissue appears on the image. Hyperintense means the tissue appears brighter than the surrounding structures, which usually indicates a high water content, often seen in inflammation or edema on T2-weighted images. Conversely, a Hypointense area is darker, which can represent dense tissue like bone, air, or a decrease in normal fatty tissue on T1-weighted images. Isointense means the tissue has a signal intensity similar to the adjacent structures.
Pathological descriptions are also common in the report, starting with the general term Lesion, which simply refers to any area of abnormal tissue. A Mass or Tumor indicates an unexpected growth or volume of tissue, which can be benign or malignant. Edema specifically describes an abnormal accumulation of fluid, which typically appears hyperintense on T2 images due to the increased water content.
In spinal imaging, specific mechanical terms frequently appear. Herniation describes the displacement of disc material, such as the jelly-like center pushing through the outer ring of an intervertebral disc. Stenosis refers to the narrowing of a passage, such as the spinal canal or the neural foramen, which can compress nerve roots. The report may also mention Degenerative changes, which refer to expected wear-and-tear findings like disc desiccation or bone spurs (osteophytes) common with age.
Visualizing Anatomy on the Scan
Beyond the written report, understanding how the images are oriented can help you visualize the findings described. MRI scans are typically presented in three standard viewing planes, each providing a distinct cross-sectional perspective of the body.
The Axial plane, also known as the transverse plane, creates slices horizontally, dividing the body into upper and lower sections, similar to looking down at a slice of bread. This view is particularly useful for assessing structures like intervertebral discs and the spinal cord in cross-section.
The Sagittal plane divides the body vertically into left and right halves, offering a profile or side view of the structures. This perspective is effective for viewing the alignment of the spine or the full extent of a tumor. The Coronal plane is the third orientation, creating slices that divide the body into front (anterior) and back (posterior) sections.
Normal tissues present with predictable signal intensities across these planes. For instance, the hard outer shell of bone typically appears dark on both T1 and T2 sequences because it contains few mobile hydrogen atoms. Conversely, bone marrow, which is rich in fat, appears bright on T1-weighted images. Recognizing the normal appearance of fat, fluid, and muscle makes it easier to spot an abnormality, which stands out as an unexpected deviation in signal intensity or structure.
Integrating Results and Next Steps
Once the MRI scan is complete, the images are sent to a radiologist for interpretation, which typically takes 24 hours to a few days for a full report. A Preliminary report may be issued quickly if an urgent finding is suspected. The Final report is the official, signed document, reviewed and approved by an attending radiologist. While discrepancies are generally minimal, the final version is the definitive interpretation used for diagnosis.
The radiologist writes the report for the referring physician, who is responsible for integrating the imaging findings with your clinical history, physical examination, and symptoms. The final diagnosis and treatment plan are formulated only after this comprehensive review. Before your follow-up appointment, it is helpful to review the Impression section and prepare specific questions about how the findings correlate with your symptoms and what the recommended next steps entail.