Understanding Your Radiology Report: What Every Term Means

What Is a Radiology Report?

A radiology report is the official written interpretation of a medical imaging study — whether a CT scan, MRI, X-ray, ultrasound, PET scan, or nuclear medicine exam. It is authored by a board-certified radiologist who reviews the images and documents their findings in structured, standardized language.

Every radiology report follows the same four-part architecture: clinical indication, technique, findings, and impression. Understanding this structure turns a confusing document into a readable, actionable clinical communication. The report is both a clinical record and a legal document — radiologists choose every word carefully.

Key insight: The Impression section is the radiologist's bottom line. If you only have 30 seconds, read the Impression. The Findings section contains the supporting evidence; the Impression contains the conclusion.

Anatomy of a Report: Section by Section

Clinical Indication

This section states why the imaging was ordered — the clinical question the radiologist is answering. For example: "Chest pain, rule out pulmonary embolism" or "Follow-up of known thyroid nodule." The indication frames the entire interpretation. A radiologist reading a chest CT for PE will focus on the pulmonary vasculature differently than one reading for lung cancer screening.

Technique

The technique section describes how the study was performed: modality (CT vs. MRI vs. ultrasound), body region imaged, whether intravenous or oral contrast was administered, and any special protocols used. For CT studies, the technique section may also note the radiation parameters. If you want to understand the dose your patient received, the CT Radiation Dose Calculator converts CTDIvol and DLP values — found in the technique section — to effective dose in millisieverts.

Findings

The findings section is the radiologist's organ-by-organ (or region-by-region) description of what they observed. It is deliberately exhaustive — every structure within the field of view is commented upon, even if normal. You will see entries like "Heart: normal in size and configuration" or "Liver: homogeneous, no focal lesion." Measurements are recorded here: nodule dimensions, organ sizes, fluid collections.

This thoroughness is intentional. If a finding isn't mentioned in the Findings, it was either not seen or considered normal. Incidental findings — things noted outside the primary indication — also appear here.

Impression

The Impression is the radiologist's interpretive conclusion: a prioritized summary of the most clinically important findings, with recommendations for next steps when appropriate. Impressions use numbered lists, with the most significant finding listed first. A phrase like "1. No acute cardiopulmonary process" is unambiguously reassuring. "1. 8mm right upper lobe pulmonary nodule — recommend follow-up per Fleischner guidelines" tells the ordering clinician exactly what action to take.

Common Radiology Terms Decoded

Radiology has its own vocabulary. Here are the terms patients and non-radiologist clinicians encounter most often:

• No acute findings — No urgent or new abnormality was identified for the clinical question asked. Chronic findings (old fractures, degenerative changes) may still be present and described in Findings.
• Incidental finding — Something noted that wasn't the reason for the scan. Most incidental findings are benign. Common examples: small kidney cysts, liver hemangiomas, lung nodules, adrenal adenomas.
• Lesion — A nonspecific term for any abnormality; it carries no implication about malignancy.
• Nodule — A small, round, well-defined density. In the lung, a nodule is typically <3 cm. In the thyroid, management follows TI-RADS guidelines. In the breast, workup follows BI-RADS. In the prostate, MRI assessment uses PI-RADS.
• Mass — A larger abnormality, typically ≥3 cm in the lung. Size alone does not confirm malignancy, but larger masses warrant more urgent workup.
• Enhancement — An area that increases in density or signal after contrast administration. Enhancement implies vascularity and can indicate inflammation, infection, or neoplasm.
• Lucency — An area that appears darker (less dense) on imaging. On X-ray, a lucency in bone suggests bone destruction or air.
• Opacity — An area that appears brighter (more dense) than expected. Ground-glass opacity in the lung indicates partial filling of air spaces and can represent infection, edema, or early malignancy.
• Artifact — An imaging abnormality caused by the equipment or patient motion, not a real anatomical finding. Streak artifacts on CT from metal implants are a common example.

For pulmonary nodules specifically, Fleischner Society Guidelines determine whether follow-up CT is needed and at what interval, based on nodule size, morphology, and patient risk factors.

Structured Reporting Systems (RADS)

The American College of Radiology (ACR) has developed standardized lexicons — called RADS systems — that assign numerical categories to imaging findings in specific organ systems. These systems eliminate ambiguity by giving every finding a category with a defined clinical action.

You may see RADS categories referenced directly in a radiology report's Impression. Here are the four systems available on Radcalcs:

• TI-RADS — Thyroid Imaging Reporting and Data System. Categories 1–5 guide fine-needle aspiration (FNA) biopsy decisions for thyroid nodules based on ultrasound features.
• PI-RADS — Prostate Imaging Reporting and Data System v2.1. Categories 1–5 guide biopsy decisions for prostate MRI findings.
• BI-RADS — Breast Imaging Reporting and Data System, 5th Edition. Categories 0–6 guide biopsy, follow-up, and treatment decisions for breast imaging findings on mammography, ultrasound, and MRI.
• Fleischner Criteria — Fleischner Society Guidelines for incidental pulmonary nodules on CT. Determines follow-up interval based on nodule size, morphology (solid vs. subsolid), and patient risk factors.

When a radiologist writes "TI-RADS 4 nodule — FNA recommended for nodules ≥15mm," they are applying the ACR TI-RADS algorithm. The number is not arbitrary — it maps to a specific probability of malignancy and a guideline-directed management pathway.

When a Report Recommends Follow-Up

Follow-up recommendations in radiology reports fall into three broad categories, each with a different urgency:

Short-interval follow-up

Phrases like "3-month follow-up CT recommended" or "repeat ultrasound in 6 months" indicate findings that are most likely benign but need monitoring to confirm stability. A nodule that stays the same size over 2 years is almost certainly not cancer. Short-interval follow-up is the radiologist's way of saying: "I'm not worried enough to recommend biopsy now, but let's confirm this doesn't change."

Correlation with prior imaging

"Comparison with prior imaging is recommended" means the radiologist needs to know whether this finding is new or old. A lung nodule that's been stable for 5 years is reassuring; the same nodule appearing for the first time is more concerning. If prior imaging exists, make sure the radiology group has access to it before the read — it changes the Impression significantly.

Clinical correlation recommended

"Clinical correlation is recommended" is radiology's way of saying: "This finding's significance depends on the patient's symptoms and physical exam, which I don't have access to." It is an invitation for the ordering provider to synthesize the imaging with the rest of the clinical picture — not a red flag on its own.

If a report recommends a repeat CT, patients often wonder about cumulative radiation exposure. The CT Radiation Dose Calculator can help quantify dose in mSv and compare it to ACR benchmark values, which is useful context for shared decision-making conversations.

Frequently Asked Questions