SPECT-CT: Definition, Uses, and Clinical Overview

Posted on February 28, 2026 | by drhip

SPECT-CT Introduction (What it is)

SPECT-CT is a medical imaging test that combines two scan types in one session.
It shows both bone or tissue activity (function) and detailed anatomy (structure).
It is commonly used in orthopedics to evaluate hard-to-explain joint pain, including hip pain.
It is a diagnostic tool, not a treatment.

Why SPECT-CT used (Purpose / benefits)

Orthopedic symptoms often come from a mix of problems: bone stress, inflammation, healing, implant-related changes, or subtle fractures. Standard imaging sometimes shows anatomy clearly but cannot confirm whether a finding is active (currently irritated, healing, or overloaded) or incidental (present but not responsible for symptoms).

SPECT-CT is used to help solve that gap by combining:

SPECT (Single Photon Emission Computed Tomography): a nuclear medicine scan that highlights areas with increased or decreased radiotracer uptake, which can correlate with processes like bone remodeling, blood flow changes, or inflammation (depending on the tracer and protocol).
CT (Computed Tomography): an x-ray–based scan that shows bone detail and alignment with high spatial resolution.

Together, SPECT-CT can help clinicians:

Localize the pain generator when symptoms and exam findings are unclear or when multiple abnormalities are present.
Increase confidence in whether a CT-visible finding is likely to be clinically meaningful.
Evaluate post-surgical joints, where MRI can be limited by metal artifact and where x-rays may not explain persistent symptoms.
Assess complex anatomy (pelvis, hip, spine junctions) where pain can be referred and overlapping conditions are common.

The overall “problem it solves” is diagnostic uncertainty—helping the care team match symptoms with the most relevant structural and biologic findings.

Indications (When orthopedic clinicians use it)

Orthopedic and sports medicine clinicians may use SPECT-CT in scenarios such as:

Persistent hip, groin, buttock, or pelvic pain with inconclusive x-ray, CT, or MRI
Suspected stress reaction or stress fracture, especially when early changes are subtle
Evaluation of pain after hip replacement (arthroplasty), including questions about loosening or abnormal load patterns (varies by clinician and case)
Differentiating potential sources of pain around the hip region, such as:
Hip joint vs sacroiliac (SI) joint vs lumbar spine–related pain patterns
Suspected occult fracture (a fracture not clearly seen on initial imaging)
Suspected bone lesion where metabolic activity may help characterization alongside anatomy (interpretation depends on clinical context)
Suspected heterotopic ossification activity (bone formation in soft tissues) in selected cases
Evaluation of focal bone pain where CT shows changes but clinical significance is unclear

Exact indications vary by clinician, facility, and local imaging pathways.

Contraindications / when it’s NOT ideal

SPECT-CT is not suitable for every patient or question. Situations where it may be avoided or where another approach may be preferred include:

Pregnancy or situations where radiation exposure should be minimized (decision-making is case-dependent)
Inability to lie still or tolerate the scanner position due to pain, severe anxiety, or certain medical conditions
When a different imaging test is more direct for the suspected diagnosis, for example:
MRI for many soft-tissue problems (labrum, cartilage, tendons) when metal artifact is not a major limitation
Ultrasound for dynamic tendon or bursal assessment in appropriate settings
When the clinical question does not require “activity” information (CT alone or x-ray may be sufficient)
Severe kidney disease or iodinated contrast allergy if a diagnostic CT with contrast is planned (many SPECT-CT protocols use low-dose CT without contrast; this varies by protocol)
Body size or equipment constraints (scanner table limits vary by manufacturer and site)
Limited availability or when the result is unlikely to change next steps (varies by clinician and case)

How it works (Mechanism / physiology)

SPECT-CT works by pairing physiologic signal with anatomic detail.

The physiologic principle (SPECT)

In many orthopedic applications, the “SPECT” part uses a small amount of a radiotracer injected into a vein. A commonly used class of tracers in bone imaging (protocol-dependent) is technetium-99m–labeled compounds that localize in areas of bone turnover and blood flow. Areas with increased uptake can reflect:

Bone remodeling from stress or overload
Healing after injury or surgery
Inflammatory or reactive changes near joints
Changes around implants that may or may not be clinically significant (interpretation requires context)

Importantly, SPECT uptake is not diagnosis-specific on its own. Increased activity can occur for multiple reasons, which is why clinical history, exam findings, and the CT component matter.

The anatomic principle (CT)

The “CT” part provides detailed images of:

Cortical bone (outer shell)
Trabecular bone (inner spongy bone pattern)
Joint alignment and certain structural abnormalities
Implant position and surrounding bone (with limitations depending on metal artifact and CT technique)

Relevant hip and pelvic structures

For hip-related symptoms, clinicians commonly consider:

The femoral head and neck and the acetabulum (the socket)
The hip joint space, where cartilage and the labrum contribute to motion and stability (cartilage and labrum are better assessed with MRI, but CT helps define bony shape and alignment)
The pubic symphysis, sacroiliac joints, and nearby pelvic bones, which can refer pain to the groin, buttock, or lateral hip
Post-operative structures such as hip arthroplasty components and the surrounding bone-implant interface

Onset, duration, and reversibility

SPECT-CT does not “work” like a medication and does not have a therapeutic effect. It produces a snapshot of physiologic activity and anatomy at the time of the scan. How long the results remain clinically relevant depends on whether the underlying condition is stable, healing, or changing (varies by clinician and case).

SPECT-CT Procedure overview (How it’s applied)

SPECT-CT is an imaging study performed in a radiology or nuclear medicine department. Exact workflows vary by site, but a typical high-level sequence is:

Evaluation/exam – A clinician reviews symptoms, physical exam findings, and prior imaging (x-rays, MRI, CT). – The clinical question is defined (for example, “localize active bone stress” or “evaluate painful arthroplasty”).
Preparation – The facility screens for relevant factors such as pregnancy status, ability to lie still, prior reactions, and recent imaging. – Patients may be asked about recent surgeries, injections, or implants because these can influence interpretation.
Intervention/testing – A radiotracer is administered through an IV. – After an uptake period (timing varies by tracer and protocol), imaging is performed:
- SPECT images measure the distribution of the tracer.
- CT images map anatomy and allow fusion (overlay) with SPECT findings.
Immediate checks – Technologists confirm image quality and coverage of the target region. – Some protocols include additional views if needed (varies by site).
Follow-up – A radiologist (often with nuclear medicine training) interprets the fused images. – Results are reported back to the referring clinician, who integrates them with exam findings and other tests.

SPECT-CT is generally considered a diagnostic test, and next steps depend on the broader clinical picture rather than the scan alone.

Types / variations

“SPECT-CT” describes a hybrid platform, and what it shows depends on the protocol and tracer. Common variations include:

Bone SPECT-CT
Often used for orthopedic questions involving bone remodeling, stress changes, or post-surgical assessment.
Typically uses a bone-seeking tracer (protocol-dependent).
Infection/inflammation-focused SPECT-CT
In selected scenarios, different tracers may be used to evaluate suspected infection or inflammatory activity.
Exact tracer choice and accuracy vary by clinician, case, and facility.
Low-dose CT vs diagnostic CT
Many SPECT-CT studies use low-dose CT primarily for localization and attenuation correction.
Some protocols include a higher-resolution diagnostic CT, sometimes with contrast when appropriate (contrast use varies by protocol and patient factors).
Targeted region vs broader survey
Some studies focus tightly on one area (for example, the hip and pelvis).
Others may include additional planar nuclear medicine images with targeted SPECT-CT added to the area of concern (workflow varies).
Metal artifact reduction techniques
For patients with joint replacements or hardware, CT settings and reconstruction methods may be adjusted to reduce artifact (availability varies by manufacturer and site).

Pros and cons

Pros:

Can show where bone or tissue activity is increased and match it to precise anatomy
Helpful when pain location is unclear or when multiple abnormalities are present
Often useful in post-operative or hardware-related situations where other modalities can be limited
May improve diagnostic confidence compared with SPECT-only or CT-only in selected cases
Provides 3D localization, which can support discussion among clinicians (radiology, orthopedics, sports medicine)
Can help differentiate active vs inactive findings in certain contexts (interpretation varies by case)

Cons:

Involves ionizing radiation from both the nuclear medicine component and CT
Increased uptake is not specific and can reflect several different processes
Scan time and scheduling can be more involved than standard x-rays (workflow varies)
Image quality can be affected by motion or difficulty maintaining position
CT near metal implants can still have artifact, even with optimization
Availability and insurance coverage vary by region and facility
Some patients dislike injections or have concerns about radiotracers (education and consent processes vary)

Aftercare & longevity

Because SPECT-CT is diagnostic, “aftercare” is mainly about returning to normal routines and understanding how results fit into the bigger clinical picture.

General considerations include:

Immediate recovery
Most people can resume typical activities shortly after the scan, depending on how they feel and on facility instructions.
Mild discomfort can occur at the IV site, as with other blood draws or injections.
Hydration and tracer clearance
Facilities often provide basic instructions to support normal tracer elimination; specifics vary by protocol and patient factors.
Result longevity
The imaging reflects activity at a specific point in time.
How long it remains relevant depends on whether the underlying condition is stable (for example, a chronic structural issue) or changing (for example, healing bone stress). This varies by clinician and case.
What affects how “useful” the result is
Clarity of the clinical question (a focused question generally yields a more actionable interpretation)
Time since injury or surgery (recent changes can alter uptake patterns)
Coexisting issues such as arthritis, prior fractures, or spinal/SI joint conditions
Hardware type and position, and CT artifact (varies by material and manufacturer)
Quality of prior imaging for comparison

Alternatives / comparisons

SPECT-CT is one option among several imaging and diagnostic approaches. The best match depends on the suspected cause of symptoms, the body part, and prior test results.

X-ray
Often the first step for hip pain to assess arthritis, fractures, alignment, and obvious structural changes.
Limited for early stress injuries and most soft-tissue problems.
CT (alone)
Excellent for detailed bone anatomy, fractures, and some surgical planning.
Does not directly show biologic activity; may identify findings that are present but not necessarily symptomatic.
MRI
Commonly used to evaluate soft tissues (labrum, tendons, cartilage) and bone marrow changes.
Can be limited by metal artifact in patients with certain implants, and not all patients can have MRI (for example, due to specific devices or severe claustrophobia).
Ultrasound
Useful for selected tendon, bursa, and fluid evaluations and for guiding some injections.
Limited for deep joint structures and for comprehensive assessment of bone.
Planar bone scan (without SPECT-CT)
Provides a broader survey of tracer uptake but with less precise localization than SPECT-CT.
PET/CT
Another functional-anatomic hybrid modality using different tracers and physics.
Used for specific indications; whether it is appropriate depends on the diagnostic question and local practice.
Diagnostic injections (context-dependent)
In some care pathways, image-guided anesthetic injections are used to help determine whether a joint or structure is the pain source.
These are not imaging alternatives in the strict sense, but they are sometimes compared as tools for localization. Use varies by clinician and case.

In practice, SPECT-CT is often considered when prior imaging is discordant with symptoms, when multiple potential pain sources exist, or when “activity mapping” could clarify next steps.

SPECT-CT Common questions (FAQ)

Q: Is SPECT-CT the same as a regular CT scan?
No. CT shows anatomy (structure), while SPECT-CT combines CT with SPECT, which shows physiologic activity from a radiotracer. The combined study is designed to localize activity to a precise anatomic location.

Q: Why would someone with hip pain be sent for SPECT-CT?
Hip and pelvic pain can come from the hip joint, nearby pelvic joints, stress-related bone changes, or post-surgical issues. SPECT-CT may help when other imaging does not clearly identify the active pain source or when multiple abnormalities exist.

Q: Does SPECT-CT hurt?
The scan itself is usually not painful. Some people feel brief discomfort from the IV placement and may feel uncomfortable lying still, especially if hip pain is position-sensitive.

Q: How long does a SPECT-CT appointment take?
It varies by protocol, tracer, and facility workflow. Many studies include an injection, a waiting period for tracer uptake, and then the scanning portion, so the full visit can be longer than a standard x-ray or CT.

Q: How safe is SPECT-CT?
SPECT-CT uses ionizing radiation from both the tracer and the CT component. Clinicians and imaging teams weigh expected diagnostic value against radiation exposure, and protocols are often adjusted to the clinical question (varies by site).

Q: Will SPECT-CT show labral tears or cartilage damage in the hip?
SPECT-CT is primarily used to assess activity patterns and bony anatomy. Labrum and cartilage are generally better evaluated with MRI or MR arthrography, though CT can help assess bony morphology that contributes to impingement patterns.

Q: When will I get results?
Timing depends on facility workflow and how results are communicated to the referring clinician. Images typically require interpretation by a radiologist, and the final report is then reviewed alongside your history and exam.

Q: How much does SPECT-CT cost?
Costs vary widely by region, facility type, insurance coverage, and whether the CT portion is low-dose or diagnostic. For a meaningful estimate, facilities usually provide a pre-authorization or pricing process tailored to the specific protocol.

Q: Can I drive or go back to work after SPECT-CT?
Many people can return to normal activities afterward, but individual instructions vary by facility and by how you feel after the appointment. If you received medications for anxiety or pain as part of the visit (not always done), activity restrictions may differ.

Q: How long do SPECT-CT findings “last”?
The scan reflects what was active at the time it was performed. Some findings may remain relevant for a long time (for example, stable structural issues), while others can change as injuries heal or loading patterns change—this varies by clinician and case.