How to Prepare for Medical Imaging: A Guide by Scan Type

Proper preparation for medical imaging ensures the best possible image quality, which leads to more accurate diagnosis. If you arrive unprepared - for example, you haven't fasted when required or you're wearing metal clothing - your scan may need to be rescheduled, or the image quality may be compromised.

Different scan types require different preparation. Some (like X-rays) need almost nothing. Others (like abdominal ultrasounds or PET scans) have specific requirements that directly affect image quality.

This guide gives you preparation instructions for every major scan type in Australia. Your imaging clinic will also give you specific instructions when you book - always follow their advice as it may be tailored to your particular scan protocol.

X-rays are the simplest imaging test to prepare for:

• No fasting required • Wear comfortable clothes without metal in the area being scanned • Remove jewellery, watches, belts, and piercings from the scan area • Tell the radiographer if you are or might be pregnant • Bring your referral and Medicare card

That's it. Most X-rays take less than 10 minutes and you can eat, drink, and take medications normally beforehand.

Special cases: • Abdominal X-ray - You may be asked to remove clothing below the waist and wear a gown • Barium swallow/enema - This is a special X-ray procedure that requires fasting and bowel preparation. The clinic will provide detailed instructions. • Dental X-ray (OPG) - Remove earrings, necklaces, glasses, and any facial piercings

Ultrasound preparation depends on which body part is being scanned:

Abdominal ultrasound (liver, gallbladder, kidneys, pancreas, spleen): • Fast for 6-8 hours before the scan (no food or milk) • Water is usually OK - and staying hydrated is encouraged • Take regular medications with water unless told otherwise • The fasting reduces gas in the bowel which can obscure images

Pelvic ultrasound (bladder, uterus, ovaries, prostate): • Drink 1 litre of water, finished 1 hour before your appointment • Do NOT empty your bladder - a full bladder acts as an acoustic window for pelvic imaging • If also having an abdominal ultrasound at the same time, follow fasting AND full bladder instructions

Pregnancy ultrasound: • Early pregnancy (before 12 weeks) - full bladder usually required • Later pregnancy (after 12 weeks) - no special preparation, though the clinic may request a partially full bladder

Musculoskeletal ultrasound (shoulder, knee, ankle, etc.): • No special preparation needed • Wear clothing that allows easy access to the area being scanned

Thyroid / breast / testicular ultrasound: • No special preparation needed

CT scan preparation depends on whether contrast dye is being used:

CT without contrast: • Usually no fasting required • Wear comfortable clothes without metal • Take regular medications as normal

CT with contrast (most common): • Fast for 4-6 hours before the scan (no food; water is OK and encouraged) • You may need a blood test beforehand to check kidney function (eGFR/creatinine) - especially if you're over 60, have kidney disease, or take metformin • Tell the clinic about any allergies, especially to iodine or contrast dye • If you take metformin (for diabetes), you may need to stop it for 48 hours after the scan - your doctor and clinic will advise • Continue other medications unless specifically told otherwise • Drink plenty of water before and after (helps your kidneys process the contrast)

CT colonography (virtual colonoscopy): • Requires full bowel preparation (similar to a colonoscopy) • Low-fibre diet for 2-3 days before • Bowel cleansing solution the day before • The clinic will provide a detailed preparation kit

MRI scans have the most important preparation requirements due to the powerful magnets:

Metal safety (critical): • Remove ALL metal from your body - jewellery, watches, hair clips, piercings, glasses, hearing aids, dentures with metal • Disclose ALL implants to the clinic when booking - pacemakers, cochlear implants, joint replacements, aneurysm clips, metal plates/screws, IUD, spinal stimulators • Disclose any history of metal fragments in your body (e.g., from grinding, welding, or shrapnel) • Some implants are MRI-safe but the clinic MUST verify this before the scan

General preparation: • Wear comfortable metal-free clothing (the clinic will usually provide a gown) • No fasting required for most MRI scans (exception: some abdominal MRI or MRCP may require fasting) • If contrast (gadolinium) is being used, a blood test for kidney function may be needed • If you have claustrophobia, tell the clinic when booking - they may offer mild sedation, music, or an open MRI scanner

On the day: • Allow 30-90 minutes for the full appointment (the scan itself is 20-60 minutes) • You'll need to stay very still - even small movements blur the images • The scanner is loud (knocking/banging sounds) - you'll be given earplugs or headphones • Arrange a driver only if sedation is being used

For children needing MRI, see our guide on preparing your child for imaging.

PET scans have the most detailed preparation requirements:

• Fast for 4-6 hours before the scan (no food, chewing gum, or lollies - water only) • No strenuous exercise for 24-48 hours before - active muscles absorb the tracer and can affect results • Wear warm, comfortable clothing - being cold activates brown fat which absorbs the tracer • If you have diabetes, tell the clinic when booking - blood sugar levels need to be carefully managed. You may receive specific instructions about insulin and medication timing. • Avoid caffeine for 24 hours if having a cardiac PET scan • Tell the clinic about all medications you're taking

On the day: • You'll receive an injection of radioactive tracer into your arm • You'll then rest quietly for 60-90 minutes while the tracer distributes - no talking, no phone use, minimal movement • The scan itself takes 20-40 minutes • Total appointment time: 2-3 hours

After the scan: • Drink extra water to flush the tracer • Avoid close contact with pregnant women and young children for a few hours • Resume normal activities immediately

DEXA scans (bone density) require minimal preparation:

• No fasting required • Wear comfortable clothes without metal zips or buttons • Do NOT take calcium supplements for 24 hours before the scan • Tell the clinic if you've had a barium study or contrast CT in the past 7 days (residual contrast affects results) • Tell the clinic if you might be pregnant • Bring previous DEXA results if you have them (for comparison)

The scan itself takes only 10-20 minutes. You lie on your back on an open table - there's no tunnel or enclosed space.

Regardless of your scan type, these tips will make your appointment smoother:

• Confirm preparation instructions when booking - don't rely on memory or general guides alone. Your clinic may have specific requirements. • Set a reminder - if you need to fast, set an alarm for when to stop eating • Arrive 10-15 minutes early - for paperwork and screening questions • Bring your referral and documents - don't assume the clinic has everything • Tell the clinic about pregnancy - real or possible. This affects X-ray, CT, and some MRI scans. • Tell the clinic about allergies - especially to contrast dye, iodine, or latex • Ask questions - if you're unsure about any instruction, call the clinic. They'd rather answer a question than reschedule because of incorrect preparation.

Ready to book? Search for imaging clinics near you on Radly and find the best appointment for your scan.