Many patients accidentally make small mistakes before a PET-CT scan, such as drinking tea or coffee, eating a light snack, exercising, or forgetting to mention that they have diabetes. While these may seem harmless, they can affect how the tracer works inside your body, reducing image quality and sometimes even requiring the scan to be rescheduled.

The good news is that preparing for a PET-CT scan is simple. You mainly need to fast for a few hours, stay hydrated with plain water, avoid strenuous physical activity, wear comfortable clothing, and follow any specific instructions given by your doctor, especially if you have diabetes or take regular medications. This guide explains exactly what you should do before, during, and after your PET-CT scan to help ensure accurate results and a smooth experience.

Before your PET-CT scan, remember these essential instructions:

• Fast for 4–6 hours before your scan.
• Drink plain water to stay hydrated.
• Avoid tea, coffee, juice, milk, sugar, sweets, and chewing gum.
• Skip gym, running, and heavy exercise for 24 hours.
• Wear loose, comfortable clothing and avoid metal accessories.
• Tell us if you’re diabetic, pregnant, breastfeeding, or taking regular medicines.
• Rest quietly after the tracer injection.
• Drink plenty of water after the scan.

Following these instructions helps produce clearer images and reduces the chances of repeat imaging.

Preparing correctly helps your PET-CT scan produce clear and accurate images. Even small mistakes, such as eating before the scan or exercising, can affect how the tracer is absorbed and may lead to unclear results or, in some cases, a repeat scan.

Following the preparation instructions helps:

• Improve scan accuracy
• Reduce the chances of repeat imaging
• Help detect abnormalities more clearly
• Support faster and more reliable reporting
• Assist your doctor in making the right treatment decisions

At Orbit Imaging, we provide every patient with clear preparation instructions before the appointment, helping ensure a smooth experience and the most accurate diagnostic results.

Preparing for a PET-CT scan isn’t difficult, but following each instruction carefully can make a significant difference. Here’s everything you should do before your appointment.

1. Fast Before Your PET-CT Scan

Fasting is one of the most important preparation steps. In most cases, you should not eat anything for 4–6 hours before your scan. You may drink plain water unless your doctor advises otherwise.

Avoid:

• Tea and coffee
• Milk and fruit juice
• Soft or energy drinks
• Sugar and sweets
• Chewing gum and mouth fresheners

Why is fasting important?

The PET scan uses a glucose-based tracer. Eating before the scan, especially sugary or carbohydrate-rich foods, can affect how the tracer is absorbed and reduce scan accuracy.

Accidentally ate something?

Don’t worry, but don’t ignore it either. Call us before your appointment so we can advise whether your scan can proceed or needs to be rescheduled.

2. Stay Well Hydrated

Although you need to fast, you should continue drinking plain water before your appointment.

Staying hydrated:

• Helps the tracer circulate properly
• Makes IV insertion easier
• Supports flushing the tracer after the scan

Drink water regularly instead of all at once just before your appointment.

3. Avoid Exercise Before the Scan

Avoid strenuous exercise for at least 24 hours before your PET-CT scan.

This includes:

• Running
• Gym workouts
• Cycling
• Weight training
• Heavy lifting

Why?

Exercise increases glucose uptake in your muscles, which can affect the PET scan images. Light daily activities, such as walking, are usually fine unless your doctor advises otherwise.

4. Wear Comfortable Clothing

Wear loose, comfortable clothing on the day of your scan.

We recommend:

• Comfortable cotton clothes
• Loose-fitting trousers or track pants
• Clothing with minimal metal

You may also be asked to remove jewellery, watches, belts, or other metal items before the scan.

5. Tell Us About Your Medical History

Before your appointment, let us know if you:

• Have diabetes
• Are you pregnant or breastfeeding
• Have had recent surgery
• Have an infection or fever
• Take regular medicines
• Have kidney problems
• Feel anxious or claustrophobic

Sharing your medical history helps us prepare you properly and ensures accurate, safe imaging.

6. PET Scan Preparation for Diabetic Patients

If you have diabetes, your preparation may be slightly different because blood sugar levels can affect PET-CT results.

To prepare:

• Follow the fasting instructions carefully.
• Don’t change your insulin or diabetes medicines without your doctor’s advice.
• Check your blood sugar if instructed.
• Inform us if your sugar levels are unusually high or low.

Our team will guide you on the best appointment timing based on your medication and blood sugar levels.

7. Can You Take Medicines Before a PET-CT Scan?

Most regular medicines can be taken with plain water, but some diabetes medicines or insulin may require special timing.

Never stop taking your prescribed medicines unless your doctor tells you to. If you’re unsure, contact us before your appointment, and we’ll guide you based on your medical condition.

Many patients worry because they don’t know what to expect. Fortunately, the procedure is straightforward, painless, and performed by trained professionals who guide you throughout the process.

Here’s how your appointment usually progresses:

Registration and Verification

When you arrive, we’ll verify your details, review your doctor’s prescription, and confirm that you’ve followed the preparation instructions. Depending on your medical history, we may also check your blood sugar level before proceeding.

Tracer Injection

A small intravenous injection containing the PET imaging tracer is administered into a vein in your arm. Most patients describe this as similar to a routine blood test.

Resting Period (45–60 Minutes)

After the injection, you’ll rest quietly in a comfortable room while the tracer circulates throughout your body.

This waiting period is extremely important. During this time, you should:

• Relax quietly.
• Avoid unnecessary talking.
• Avoid walking around unless required.
• Stay warm and comfortable.
• Avoid reading, exercising your muscles, or using electronic devices excessively if instructed.

Remaining relaxed helps ensure the tracer distributes naturally and produces high-quality images.

The PET-CT Scan

Once the waiting period is complete, you’ll lie comfortably on the scanning table while it moves slowly through the scanner.

The scan itself usually takes about 20–30 minutes. During this time, you’ll simply need to remain still while images are acquired.

The procedure is painless, and our technologists monitor you throughout the examination.

Recovery after a PET-CT scan is usually simple, and most people return to their normal routine the same day.

After your scan, you should:

• Drink plenty of water throughout the day.
• Resume eating unless your doctor has advised otherwise.
• Continue taking your prescribed medications.
• Follow any additional instructions provided by your healthcare team.

Some patients may be advised to minimise prolonged close contact with pregnant women or very young children for several hours after the scan. This is a routine precaution because a small amount of radioactive tracer remains in your body for a short period before being naturally eliminated.

Even well-informed patients sometimes make simple mistakes that can interfere with scan quality.

Some of the most common include:

• Eating breakfast because they “felt hungry.”
• Drinking tea or coffee without thinking about it would matter.
• Chewing gum during the fasting period.
• Exercising at the gym the previous evening.
• Smoking shortly before the appointment.
• Arriving without previous medical reports.
• Not informing us about diabetes or recent surgery.
• Becoming dehydrated by avoiding water altogether.

At Orbit Imaging, we spend time reviewing preparation instructions before every appointment because preventing these mistakes is far easier than repeating a scan.

Can I drink water before a PET scan?

Yes. Plain water is encouraged unless your doctor has advised otherwise. Staying hydrated improves comfort and supports accurate imaging.

Can I take my blood pressure medicine?

In many cases, yes. However, always follow your doctor’s advice and inform our team about every medication you take.

Can diabetic patients undergo a PET-CT scan?

Absolutely. Diabetic patients can safely undergo PET-CT imaging with appropriate preparation and blood sugar management.

Can I brush my teeth before the scan?

Yes. You may brush your teeth, but avoid swallowing toothpaste and avoid sweetened mouthwash.

Can I smoke before a PET scan?

Smoking should be avoided before your appointment. Nicotine may influence your body’s metabolism and can interfere with optimal preparation.

Can I chew gum?

No. Even sugar-free gum can stimulate metabolic activity and should be avoided during the fasting period.

Is the PET-CT scan painful?

The scan itself is painless. Apart from the small IV injection used to administer the tracer, most patients experience little to no discomfort.

Can I drive home afterwards?

In most cases, yes. Unless your doctor has given special instructions or you’ve received medication affecting alertness, you can usually drive yourself home.

Even if you prepare perfectly, your PET-CT scan is only as reliable as the technology, protocols, and expertise behind it. Choosing an experienced diagnostic centre helps ensure accurate imaging, timely reporting, and greater confidence in your diagnosis.

At Orbit Imaging, we make the entire process seamless—from clear pre-scan guidance and advanced PET-CT technology to expert reporting by experienced radiologists. With 21+ years of diagnostic excellence, NABL & NABH-accredited centres, affordable pricing, and multiple locations across Delhi NCR, we’re trusted by over 1 crore patients.

Don’t compromise on a scan that plays a crucial role in your treatment decisions. Book your PET-CT scan at Orbit Imaging today and let our experts guide you every step of the way with accurate diagnostics and compassionate care.