PET Scan Radiology: Understanding the Report

The radiology report from a PET-CT can feel intimidating to read. Phrases like "no abnormal FDG uptake" or "indeterminate finding" mean specific things to a radiologist, but their meaning is not always obvious to a patient. This light guide walks through how a PET-CT report is written, what to look for, and how to discuss findings with your physician.

How a PET-CT Report Is Structured

A standard report has six sections:

1. Patient and study identifiers
2. Indication (the clinical question being addressed)
3. Technique (tracer used, dose, scan parameters)
4. Comparison (prior studies referenced)
5. Findings (the radiologist's observations, region by region)
6. Impression (synthesis and recommendation)

The most important section is the impression. It states the radiologist's clinical conclusion in plain medical language and often suggests next steps.

Key Terms in a PET Radiology Report

A short glossary:

• SUVmax: the highest single-pixel uptake in a lesion; the most cited measurement
• SUVmean: averaged SUV across a region of interest
• Physiologic uptake: normal background uptake (heart, brain, kidneys, bladder)
• Pathologic uptake: focal uptake suspicious for disease
• FDG-avid: a lesion that takes up FDG strongly
• No abnormal FDG uptake: reassuring — no concerning hot spots
• Indeterminate: doesn't fit cleanly into benign or malignant pattern
• Suspicious for malignancy / concerning for: explicit cancer concern

The report's specific wording carries weight. "Suspicious for" is stronger than "consistent with" which is stronger than "indeterminate."

Reference Tissues for SUV Comparison

Radiologists compare lesion uptake to reference tissues, particularly the liver:

• Lesion SUV ≤ mediastinal blood pool: likely benign
• Lesion SUV > mediastinum, ≤ liver: probably not active disease
• Lesion SUV > liver: suspicious — warrants attention

This comparison is the basis of the Deauville 5-point score used in lymphoma. For other cancers, the threshold is more clinical judgment based on lesion type and context.

What the Comparison Section Tells You

When prior PET studies exist, the radiologist compares directly:

• "Stable compared to prior" — no change
• "Decreased compared to prior" — treatment response (good)
• "Increased compared to prior" — disease progression or new inflammation
• "New uptake at [site]" — new lesion requiring workup
• "Resolution of prior uptake" — improvement

The trajectory matters more than absolute SUV. A 30% drop in SUVmax across measurable lesions is the PERCIST criterion for partial response.

For interpreting a complex PET report, our team can help.

When to Request a Second Opinion

A second radiology read on the same PET-CT can clarify ambiguous findings. Reasons to request:

• Indeterminate findings without clear next steps
• Disagreement between prior reports
• Major treatment decisions hinging on the finding
• Concern about reading quality

International second-opinion teleradiology costs ¥1,000-2,500 in China with 24-72 hour turnaround. Send DICOM files (not just JPEG) for a definitive re-read.

Asking Your Doctor the Right Questions

Useful questions for your physician:

• "What is the SUVmax of the highest-uptake lesion compared to the liver?"
• "Is this physiologic uptake or pathologic?"
• "Has it changed from my previous scan?"
• "What are the alternatives if it isn't cancer?"
• "What is the next step?"

A 15-minute conversation typically converts an alarming-sounding report into a manageable plan.

Frequently Asked Questions

My report says "indeterminate." What does that mean?
The finding doesn't fit cleanly into benign or malignant patterns. Standard resolution is a follow-up scan in 3 months — if it shrinks or disappears, it was likely inflammation; if it grows, further workup.

Why is my SUV different from a previous scan when I haven't been treated?
Day-to-day SUV variation of 15-25% is normal — depends on blood glucose, body weight, scan timing, and scanner calibration. Differences under 30% are usually noise.

Can the impression say "cancer" outright?
Rarely. Radiology reports use careful language because biopsy provides definitive diagnosis. The impression typically describes patterns and recommends biopsy when malignancy is suspected.

Should I request the original DICOM images?
Yes, especially if you may need a second opinion or future comparison. Most imaging centers can provide DICOM on a USB drive or via secure online transfer.

Need Help Booking?

SinoCareLink can pre-book PET-CT or arrange teleradiology second-opinion reads at a top Chinese hospital, translate reports into English, and arrange airport pickup. Contact us for a free consultation.