PET-CT Examination: Patient Walkthrough
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A first PET-CT examination is unfamiliar to most patients. The combination of IV injection, one-hour waiting period, and unusual scanner can feel intimidating without a clear preview. This light guide walks through the typical exam from arrival to results.
Day Before: Fasting and Diet Rules
For a standard FDG PET-CT:
- 6-12 hours fast before the scan (water only)
- No sugary drinks, juice, or carbohydrates the day of
- No strenuous exercise 24 hours before
- Take regular medications with sips of water
- Diabetics: special blood sugar management with your physician
For specialized scans (cardiac sarcoid, brain dementia, etc.), the prep is more elaborate. Your imaging center will provide specific instructions.
Arrival and Check-In
You arrive 30-60 minutes before the scheduled scan:
- Registration and consent
- Vitals (weight, height, blood pressure)
- Blood glucose check (must be <200 mg/dL or <11 mmol/L typical)
- Recent surgery, infection, or chemotherapy disclosure
- Pregnancy test if applicable
Wear loose comfortable clothing without metal. Some centers provide a gown.
Tracer Injection
A small IV catheter is placed in the arm. The radioactive tracer (FDG, typically 8-15 mCi for an adult) is injected over 10-30 seconds, followed by saline flush. The injection itself is painless — only the IV stick.
No warm flush, no taste, no nausea. The tracer cannot be felt.
The Uptake Phase
After injection, you rest quietly in a designated room for approximately 60 minutes while the tracer circulates and accumulates in active tissue.
Rules during uptake:
- Stay still and relaxed
- No talking, chewing, or vocal activity
- No reading aloud, no phone calls
- Warm environment to prevent brown fat activation
- Water sips only
You can listen to quiet music, scroll your phone silently, or rest with eyes closed. Sleep is fine.
On the Scanner
When uptake is complete:
- Bathroom break (empty bladder; FDG is excreted in urine)
- Position on scanner table lying flat
- Imaging starts; table moves slowly through the PET ring
- Scan duration: 20-30 minutes for whole-body
- Stay still and breathe normally; brief breath-holds at start/end
The PET ring is short (~70 cm) — much less claustrophobic than MRI. The scanner is silent compared to MRI.
For specific information about your scan type before booking, our team can help.
After the Scan
- IV catheter removed
- Drink 1-2 liters of water in next 4-6 hours
- Avoid close contact with pregnant women and small children for 6 hours
- Normal activity resumes immediately
- Driving is fine
The F-18 tracer has a 110-minute half-life. By the next morning, essentially all radioactivity has decayed.
Results Timeline
Standard timelines:
- US hospital: 24-72 hours
- UK NHS: 1-2 weeks
- UK private: 2-5 business days
- Mainland China (top tier): 24-48 hours
Report and image disc (DICOM) available for the patient on request. For international patients, top Chinese centers can email both directly.
Frequently Asked Questions
Can I take my medications before the scan?
Yes, with sips of water, unless instructed otherwise. Diabetes medications need specific timing.
What if I'm claustrophobic?
PET scanners are much shorter than MRI machines. Most claustrophobic patients tolerate them well. Mild sedation is possible if needed.
How long do I stay radioactive?
F-18 half-life is 110 minutes. By 18 hours after the scan, residual activity is negligible.
Will I feel different during the scan?
No. The tracer is biologically silent. The scanner is quiet. The experience is largely peaceful — most patients describe the most uncomfortable part as the 60-minute wait, not the actual scan.
Need Help Booking?
SinoCareLink can pre-book PET-CT at a top Chinese hospital, send detailed prep instructions in English, translate reports, and arrange airport pickup. Contact us for a free consultation.