The impression is the radiologist’s bottom-line summary of what your imaging study shows. It appears at the end of the report and distills everything the radiologist observed into the most important takeaways: what they think is going on, what they’re less sure about, and what they recommend doing next. If you only read one section of your radiology report, this is the one your doctor focuses on too.
How a Radiology Report Is Organized
A radiology report typically has several sections, and understanding the layout helps you make sense of the impression. At the top, you’ll see basic details: the type of exam (CT, MRI, X-ray, ultrasound), the body part scanned, and the clinical reason your doctor ordered it. Below that comes the “Findings” section, which is the longest and most technical part. This is where the radiologist describes everything they see, organ by organ or structure by structure, in detailed medical language.
The impression sits at the bottom and serves a completely different purpose. While the findings are comprehensive and descriptive, the impression is interpretive. It’s where the radiologist steps back from the details and tells your doctor: here’s what matters. Think of findings as the raw observations and the impression as the expert opinion about what those observations mean.
What the Impression Typically Contains
The American College of Radiology requires that every radiology report include an impression or conclusion unless the report is already very brief. According to ACR guidelines, the impression should provide a specific diagnosis when possible. When the radiologist can’t pin down a single diagnosis, they’ll list a differential diagnosis, which is a short list of the most likely explanations ranked by probability. The impression may also recommend follow-up imaging or additional tests to clarify something uncertain, and it must note any significant adverse event that occurred during the study.
In practice, an impression might be as simple as one line (“No acute abnormality”) or several numbered items covering different findings. For example, a CT scan of your abdomen might have an impression that reads: “1. No evidence of appendicitis. 2. Small kidney stone in the left kidney, 3 mm. 3. Incidental liver cyst, benign appearing.” Each item is a separate conclusion drawn from the detailed findings above.
The Impression Is Not a Final Diagnosis
One important distinction: the radiologist’s impression is an expert interpretation of images, not a final clinical diagnosis. Your ordering doctor combines the impression with your symptoms, lab results, physical exam, and medical history to reach a diagnosis. A radiologist reading a brain MRI, for instance, can describe what a lesion looks like and suggest what it might be, but your neurologist is the one who puts all the pieces together.
This is also why you’ll sometimes see the phrase “clinical correlation recommended” in an impression. That phrase means the radiologist found something that could be significant but needs your doctor to connect it with your clinical picture. It may also signal that the radiologist wasn’t given enough background information to fully interpret a finding.
Common Terms You’ll See
Radiology impressions use specific language that can feel confusing when you’re reading your own report. Here are some of the most common terms:
- Unremarkable or within normal limits: Nothing abnormal was seen. This is good news.
- No acute abnormality: Nothing that looks new, sudden, or dangerous right now. There may be chronic (long-standing) changes noted separately.
- Acute: Something new or recent, like a fresh fracture or new fluid collection.
- Chronic: Something that has been present for a while, like old scarring or degenerative changes in a joint.
- Nonspecific: The finding doesn’t clearly point to one diagnosis. It could have several explanations.
- Incidental: Something found by chance that wasn’t related to the reason for your scan. Most incidental findings are harmless.
- Stable: Compared to a prior study, the finding hasn’t changed. Usually reassuring.
- Cannot exclude: The radiologist can’t rule something out based on the images alone and typically recommends further evaluation.
Scoring Systems in the Impression
For certain types of imaging, the impression includes a standardized score that communicates the level of concern using a numerical scale. The most widely used systems focus on cancer screening. BI-RADS appears on mammograms and breast MRIs, PI-RADS on prostate MRIs, TI-RADS on thyroid ultrasounds, and LI-RADS on liver imaging. There are also scoring systems for lung cancer screening (Lung-RADS) and coronary artery disease (CAD-RADS).
Nearly all of these systems use a stepwise numerical scale where higher numbers correspond to greater suspicion of disease. On a mammogram, for example, a BI-RADS 1 means the study is negative, while a BI-RADS 5 means there’s a highly suspicious finding. If you see one of these scores in your impression, it gives both you and your doctor a clear, standardized measure of what the next step should be, whether that’s routine follow-up or a biopsy.
Why the Impression Can Be Hard to Understand
If you’ve read your impression through a patient portal and felt lost, you’re not alone. Research on patient comprehension found that roughly half of women with abnormal mammograms didn’t understand their results were abnormal, even though federal law requires that mammography results be sent to patients in plain language. In studies comparing standard radiology reports to patient-friendly versions, comprehension scores nearly doubled when reports were rewritten in accessible terms.
The core problem is that radiology reports are written for doctors, not patients. The impression uses compressed medical shorthand that physicians parse quickly but that can leave patients confused or unnecessarily alarmed. A phrase like “nonspecific periportal edema” might sound frightening but could be a minor, clinically insignificant finding. Conversely, hedged language like “cannot exclude malignancy” might not register as urgent to someone unfamiliar with the phrasing.
How Urgent Findings Are Handled
When a radiologist spots something potentially life-threatening, the impression alone isn’t enough. Critical findings trigger a direct communication process. Many hospitals use tiered alert systems with escalating urgency levels. Immediately life-threatening findings, like a large blood vessel tear or tension pneumothorax, require the radiologist to contact your doctor within 60 minutes. Less urgent but still significant results may be communicated by page or email. The radiologist often notes in the report itself that critical results were communicated directly to the ordering physician, so there’s a documented record that the message got through.
If your impression contains language suggesting something urgent, your doctor has likely already been contacted before you even see the report in your portal. The system is designed so that time-sensitive findings don’t wait for someone to read the written report.
What to Do After Reading Your Impression
Start with the impression and read it for the overall message: is the study normal, are there findings that need follow-up, or is something clearly abnormal? If the impression recommends additional imaging or clinical correlation, that means your doctor needs to take the next step. You don’t need to schedule anything on your own based on the impression alone.
If you don’t understand a term, look at whether the impression ends with a recommendation. Phrases like “recommend follow-up ultrasound in 6 months” or “suggest correlation with clinical findings” tell you whether action is needed, even if the medical terminology is opaque. Your doctor will review the full report and explain what it means for your specific situation, including whether the findings change your treatment plan or require further workup.