Bone scan

What is a Bone Scan?

A bone scan is a specialized imaging test that evaluates the entire skeleton for abnormal bone metabolism and cell activity. This test is particularly effective at detecting bone abnormalities in their earliest stages, often before they might be visible on standard X-rays or other imaging tests.

The scan uses a small amount of radioactive material (radiotracer, in this case Tc-99m MDP) that is attracted to areas of bone that are actively remodeling or healing. This allows doctors to identify areas of abnormal bone activity throughout your entire skeleton in a single examination.

Why Might I Need a Bone Scan?

Your doctor may recommend a bone scan to:

• Diagnose bone infections (osteomyelitis)
• Evaluate unexplained bone pain
• Detect bone cancer or cancer that has spread (metastasized) to bones from other parts of the body
• Diagnose fractures that are difficult to see on X-rays (such as stress fractures or small fractures)
• Evaluate bone injuries or damage
• Monitor bone diseases such as Paget’s disease
• Assess joint abnormalities and arthritis
• Evaluate prosthetic joint complications
• Monitor response to treatment for bone conditions

What is SPECT-CT and Why Might It Be Added to My Bone Scan?

SPECT-CT combines two imaging technologies in one examination:

• SPECT (Single Photon Emission Computed Tomography): Creates detailed 3D images of the bone scan findings, showing exactly where the tracer has accumulated
• CT (Computed Tomography): Provides detailed anatomical images of your bone structure

When combined, SPECT-CT offers several advantages:

• More precise localization of abnormalities
• Better distinction between bone abnormalities and normal variants
• Improved ability to determine the exact nature of bone lesions
• Enhanced diagnostic confidence for your doctors

SPECT-CT may be added to your bone scan if:

• The regular bone scan shows an abnormality that needs further evaluation
• Your doctor specifically requests this additional imaging
• The area of concern needs more detailed imaging for diagnosis or treatment planning

How Does a Bone Scan Work?

The bone scan works because:

1. A radioactive tracer (typically a bisphosphonate compound) is injected into your bloodstream
2. This tracer travels through your bloodstream and is taken up by cells that are actively building bone (osteoblasts)
3. Areas with increased bone activity (such as fractures, infections, or tumors) will attract more tracer
4. A special camera (gamma camera) detects the radiation emitted by the tracer
5. This creates images showing where the tracer has accumulated in your skeleton
6. Areas with increased tracer uptake appear as “hot spots” on the scan

Preparing for Your Bone Scan

• No special dietary restrictions are typically required
• Continue taking your regular medications unless instructed otherwise
• Wear comfortable clothing without metal objects
• Remove jewelry and other metal objects before the scan
• Inform your healthcare team if you:
  • Are pregnant or breastfeeding
  • Have had recent imaging studies with contrast material
  • Have any allergies
  • Have difficulty lying still for extended periods

What to Expect During the Procedure

Tracer Injection

1. A small IV line will be placed in a vein in your arm
2. The radioactive tracer will be injected through this IV
3. This feels similar to having blood drawn
4. The tracer will not make you feel different or cause side effects

After Injection

1. You’ll be asked to drink plenty of water (4-6 glasses) over the next few hours
   • This helps flush excess tracer from your body
   • It also ensures good quality images
2. You’ll be asked to empty your bladder frequently, especially before imaging
   • This is important for clear visualization of your pelvic bones
3. You may be able to leave the department during the waiting period and return later

Imaging Process

Depending on your specific condition, imaging may be performed in multiple phases:

Early Phase Imaging (if needed):

• Performed immediately after injection
• Shows blood flow to the area of concern
• Particularly useful for detecting infection or inflammation
• Takes approximately 5-10 minutes

Blood Pool Phase (if needed):

• Performed 5-10 minutes after injection
• Shows tracer distribution in soft tissues
• Takes approximately 5-10 minutes

Delayed Phase (standard for all bone scans):

• Performed 2-3 hours after injection
• Allows time for the tracer to bind to bone
• Usually includes:
  1. Whole-body images (10-15 minutes)
  2. Additional targeted images as needed
  3. SPECT-CT imaging if required (adds 15-30 minutes)

SPECT-CT Procedure (if needed)

If SPECT-CT is added to your examination:

1. You’ll lie on the same examination table
2. The camera will rotate slowly around the area of interest
3. The CT portion will involve a quick scan through the same region
4. The computer will combine these images to create detailed 3D views
5. This additional imaging takes approximately 15-30 minutes
6. The CT used in SPECT-CT is typically low-dose and does not require contrast material

After Your Scan

• You can resume all normal activities immediately
• Drink plenty of fluids for the rest of the day to help flush the tracer from your body
• The small amount of radiation used will naturally leave your body within 2-3 days
• A nuclear medicine specialist will analyze your images and send a report to your doctor
• Your doctor will discuss the results with you at your follow-up appointment

What Do the Results Mean?

• Normal scan: Even distribution of tracer throughout the skeleton, with some normal variations in joints and growth areas
• Abnormal scan: Areas of increased tracer uptake (“hot spots”) that may indicate:
  • Fractures or bone injuries
  • Infection or inflammation
  • Arthritis or joint disease
  • Bone tumors (primary or metastatic)
  • Other bone diseases

SPECT-CT adds anatomical detail that helps determine the exact nature and location of abnormalities, often allowing for a more specific diagnosis.

Are There Any Risks?

The bone scan uses a very small amount of radiation. The benefits of identifying bone abnormalities far outweigh any potential risks from this minimal radiation exposure. The SPECT-CT portion adds a small additional amount of radiation, similar to a low-dose CT scan.

There are no known side effects from the tracer used in bone scans, and allergic reactions are extremely rare.

How Long Will the Entire Procedure Take?

The entire procedure typically takes 3-4 hours:

• Initial injection: 15 minutes
• Waiting period: 2-3 hours
• Standard imaging: 30-45 minutes
• Additional SPECT-CT (if needed): 15-30 minutes

If you have any questions or concerns about your bone scan, please discuss them with your healthcare provider.