A plain-language guide to understanding common lesion-related terms often seen in radiology reports.
This page explains general imaging terminology only and does not interpret or diagnose any specific findings.
What This Page Covers
This page explains commonly used radiology terms such as:• Lesion
• Nodule
• Focus / foci
• Hypodense / hyperdense (CT)
• Hypointense / hyperintense (MRI)
• Non-specific lesion
• “Area of altered signal”
• “Region of abnormality”
• Enhancement patterns (appearance-based only)If you are also reviewing terminology from MRI or CT scans, you may find additional context in MRI Terms Explained and
CT Terms Explained.
What Does the Word “Lesion” Mean?
In radiology, lesion is a neutral, general term meaning:An area that looks different from the surrounding tissue on imaging.It does not describe:
• what the area represents medically
• how it behaves clinically
• whether it is significant or insignificant
• whether it requires treatmentIt simply means the radiologist sees something that appears different from nearby structures.
Lesion vs. Nodule vs. Focus?
Radiologists use different words depending only on appearance, not on meaning:LesionA broad, general word for any area that looks different from surrounding tissue.NoduleA small, rounded area with clear borders.
Used in lungs, thyroid, soft tissues, and other organs.Focus / fociA small point-like or spot-like area that differs from surrounding tissue.These terms categorize shape and size, not medical significance.For general radiology wording, you can also visit Radiology Questions Explained
Density Terms on CT (Hypodense / Hyperdense)
HypodenseAn area appears darker than surrounding tissue on CT.
This describes visual density differences only.HyperdenseAn area appears brighter on CT.
Used to categorize appearance — not to interpret cause.These density descriptions often appear alongside other CT terminology, which you can explore at CT Terms Explained.
Non-Specific Lesion
A non-specific lesion is an area that looks different but does not have visual features that allow a precise category based on imaging alone.This wording is common and purely descriptive.
“Area of Altered Signal” or “Area of Abnormality”
These phrases simply indicate that something appears different from expected tissue appearance.They do not describe:
• what the area means medically
• whether it is important or not
• whether it relates to symptomsThey are used when radiologists describe changes without making clinical assumptions.
Why Radiology Reports Use Neutral, Descriptive Wording
Radiologists describe what they see on the images using standardized, neutral terminology. This approach ensures that the visual findings are documented clearly, consistently, and without assumptions.Descriptive wording allows radiologists to:
• Record appearance as precisely as possible
• Communicate findings in a reproducible, objective way
• Separate image appearance from clinical interpretationThe treating clinician then combines the radiology findings with symptoms, examination, and medical history to determine their clinical relevance
FAQ — Common Questions About Lesion Terminology
Does the word “lesion” indicate a specific condition?No.
In radiology, “lesion” is a general descriptive term for an area that looks different on the images.
Clinical relevance depends on the treating clinician’s evaluation.⸻Why do reports use terms like hypodense or hyperintense?These words describe how an area looks on CT or MRI.
They categorize visual appearance, not diagnosis.⸻Why is an area called “non-specific”?Some imaging findings do not have distinct visual features.
“Non-specific” means the appearance cannot be placed into a precise imaging category.⸻What does “enhancement” mean?Enhancement refers to an area that changes in brightness after contrast is used.
It is a descriptive observation about imaging appearance.⸻Why do radiologists describe shape and borders?Shape and border characteristics help categorize appearance, allowing accurate communication with the clinical team.
They do not indicate what a finding represents medically on their own.⸻Where can I learn about other terms that appear with lesion descriptions?You can explore:
• MRI Terms Explained
• CT Terms Explained
• Ultrasound Terms Explained
• Contrast Agents Explained
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