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SPECT/CT (Single Photon Emission Computed Tomography/CT)

Hybrid functional and anatomical imaging: principles, applications, and clinical advantages

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Radyoloji department. Book Appointment →

What is SPECT/CT (Single Photon Emission Computed Tomography/CT)?

SPECT/CT integrates a gamma camera (SPECT) with a CT scanner on the same gantry. SPECT detects gamma rays emitted by radiopharmaceuticals (technetium-99m, iodine-123, indium-111, gallium-67) using rotating gamma cameras with parallel-hole or pinhole collimators, producing 3D functional images. The CT component provides high-resolution anatomical reference and attenuation correction.

Common radiopharmaceuticals: 99mTc-MDP/HDP (bone), 99mTc-MIBI/Tetrofosmin (cardiac perfusion, parathyroid), 99mTc-WBC (infection), 99mTc-DMSA (renal cortex), 123I (thyroid), 111In-octreotide (neuroendocrine tumors), 67Ga-citrate (lymphoma, infection), 99mTc-MAA (lung perfusion), 99mTc-HMPAO (brain perfusion).

Clinical applications: bone scan (metastases, occult fractures, infection - SPECT/CT improves specificity from 70% to 95%), parathyroid (preoperative localization), cardiac perfusion (CAD with attenuation correction), sentinel lymph node mapping (breast, melanoma), thyroid (nodule, ectopic), neuroendocrine tumors, infection/inflammation imaging, hepatobiliary studies. Advantages: anatomical localization, attenuation correction (improves quantification), shorter imaging time, single-visit examination.

Symptoms

(SPECT/CT is a diagnostic imaging modality, not a disease)
Performed for suspected disease evaluation:
Bone pain, suspected metastases or fractures
Hyperparathyroidism (preoperative parathyroid localization)
Chest pain (cardiac perfusion imaging)
Breast/melanoma cancer (sentinel node mapping)
Suspected neuroendocrine tumor
Fever of unknown origin (infection imaging)
Renal function/anatomy assessment

Risk Factors

Indications for SPECT/CT include:
Cancer staging or metastasis evaluation
Suspected occult fracture or osteomyelitis
Hyperparathyroidism (sestamibi scan)
CAD evaluation (myocardial perfusion)
Pre-surgical sentinel node mapping
Neuroendocrine tumor surveillance
Pregnancy (relative contraindication, benefit-risk assessment)
Severe renal impairment (specific tracers)
Iodine allergy (123I, 131I imaging)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • When physician orders SPECT/CT for diagnostic workup
  • Suspected metastatic disease (bone scan)
  • Preoperative parathyroid adenoma localization
  • Stress-induced chest pain (cardiac SPECT/CT)
  • Sentinel node mapping before cancer surgery
  • Neuroendocrine tumor follow-up
  • Persistent fever, suspected occult infection
  • Equivocal CT/MRI findings requiring functional imaging

Treatment Methods

01
(SPECT/CT is diagnostic — not therapeutic)
02
Pre-procedure: appropriate radiopharmaceutical injection (timing varies)
03
Bone scan: 99mTc-MDP IV, 2-4 hour delayed imaging
04
Cardiac perfusion: rest/stress MIBI or tetrofosmin
05
Parathyroid: 99mTc-MIBI dual-phase
06
Sentinel node: 99mTc-filtered sulfur colloid 4-24 hours pre-op
07
Patient preparation: hydration, fasting (cardiac), thyroid blockade (some studies)
08
Image acquisition: SPECT (15-30 min) + low-dose CT (~30 sec)
09
Iterative reconstruction with attenuation correction
10
Radiation dose: 5-15 mSv (varies by tracer + CT)
11
Reporting: combined functional and anatomical interpretation
12
Post-procedure: hydration, no isolation needed for diagnostic doses
13
Follow-up imaging or therapy based on findings (e.g., 131I for thyroid, surgery for parathyroid)

Which Department to Visit?

You can visit our Radyoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.