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• How does SPECT CT work?
• What diseases can SPECT CT diagnose?
• SPECT CT procedure
• What are the benefits of SPECT CT?
• SPECT CT at MedPark Hospital

SPECT CT

SPECT CT is a dual-modality imaging that combines SPECT (single photon emission computed tomography) and CT (computed tomography) with the use of radioactive tracers to delineate organ function and physical abnormalities at the molecular level, e.g., checking blood flow to the heart, whether brain function is active or least active, or if cancer has spread to the bones. The SPECT CT gantry can rotate 360 degrees, providing spatial data for generating sharp, detailed 3D images, allowing for easy visualization of abnormalities, assisting in accurate result interpretation, and taking only 30 minutes to complete the examination. SPECT CT can effectively diagnose early-stage cancer, quickly analyze cancer stages, accurately detect cancer spread while using less radiation, and is a highly safe procedure.

How does SPECT CT work?

SPECT CT enables highly detailed images that combine functional information (from SPECT) with anatomical information (from CT) by fusing the images from both modalities as the details as follows:

SPECT

SPECT is a nuclear medicine scan involving using gamma camera detectors to capture the photon energy emitted by radioactive tracers from within the body. The SPECT gantry can rotate 360 degrees to gather spatial data for 3D image reconstruction of specific regions or the entire body in width, length, and oblique views, displaying the site where the radioactive tracer concentrates are gathered, assisting in the detection of lesions, cancers, tumors, or abnormalities in organ function. The bright areas on the images allow nuclear radiologists to see abnormalities in the body clearly, making it easier to interpret results, helping to separate overlapping lesions, and effectively increasing the specificity of the diagnosis.

CT

CT is a computerized tomography that provides detailed anatomical images of structures within the body in both specific regions and the entire body to collect data using x-rays. The computerized tomography system processes the digital data to create cross-sectional images from different angles in width, length, and oblique views, enabling accurate localization of internal organ structure and abnormalities, such as lesions, cancers, or tumors, which greatly aid in determining the location, size, stage, and extent of cancer spread.

Radioactive tracers

Radioactive tracers are chemicals labeled with radioactive nuclei with structures and properties that allow them to enter the body safely and harmlessly. Before the SPECT CT procedure, the nuclear radiologist will administer each person a different type and dose of radioactive tracers by injecting, swallowing, or inhaling, depending on the type of examination. When the radioactive tracers enter the body, they gather at the targeted organ or tissue of interest to be examined and gradually emit gamma photons from the area of increased uptake within the body, which can be captured in diagnostic images, allowing the SPECT CT machine to easily detect diseases or abnormalities in the body with high sensitivity and specifically.

NEUROENDOCRINE TUMOR METASTASES
(Image credit: www.siemens-healthineers.com)

What diseases can SPECT CT diagnose?

Nuclear radiologists use SPECT CT to diagnose internal organ function and detect abnormalities. The three common organs that radiologists use SPECT CT for clinical diagnosis are as follows:

BRAIN

SPECT CT assesses blood flow to the brain, checks for decreased brain function or injuries that prevent blood flow to the brain, and checks for other neurological and brain diseases, such as:

• Seizure
• Epilepsy
• Parkinson’s disease
• Stroke
• Alzheimer’s disease
• Dementia
• Traumatic brain injury (TBI)
• Moyamoya disease

HEART

SPECT CT assesses blood flow to the heart, checks for stenosis or blockage of the coronary arteries and area of myocardial ischemia, checks for myocardial fibrosis from a heart attack, assesses the efficiency of pumping blood to the heart, determines the need for coronary artery bypass grafting, and checks for cardiovascular diseases, such as

• Coronary artery disease
• Atherosclerosis
• Myocardial ischemia
• Hemodynamic disorders

BONE

SPECT CT scans for bone abnormalities generate "light up" images, allowing radiologists to detect abnormalities quickly and easily. Bone diseases and abnormalities include:

• Bone fractures
• Stress fractures
• Bone cancer
• Cancer that spreads to the bone (bone metastasis)
• Bone infections
• Jaw abnormalities

OSTEITIS PUBIS AND DEGENERATIVE LOWER LUMBAR SPINE
(Image credit: www.siemens-healthineers.com)

Preparation for SPECT CT

•    Eating and drinking are permitted prior to the examination.
•    Remove all jewelry before the examination.
•    Those who have a history of allergies to iodine or radiopharmaceuticals should inform the doctor in advance.
•    Those who take personalized medications or supplements should inform the doctor in advance.
•    Those who have a history of accidents, broken bones, fractures, or wear prosthetic organs should inform the doctor in advance.

SPECT CT procedure

• The nuclear radiologist administers the radioactive tracer through a vein via the wrist or arm. The patient will have to wait 2-3 hours for the radioactive tracer to absorb in the organ with abnormal function (depending on the type of tracer).
• While waiting, the patient drinks 1-2 liters of water to flush out any excess radioactive tracer from the body via urine, allowing the nuclear radiologist to see the abnormality.
• The nuclear radiologist will have the patient lie supine and static on the examination bed for 20-30 minutes. The SPECT CT gantry will slowly rotate 360 degrees to detect gamma photons emitted from within the body. The SPECT CT will gradually capture images around the patient and collect data on how the various organs are functioning.
• Images from SPECT and CT are combined to form a new 3D image known as a fused image, which shows the location of abnormal accumulation as a bright area of radioactive tracers (CT typically shows black and white spots), allowing the nuclear radiologist to identify small lesions, cancers, tumors, or abnormal organ function.
• Typically, a SPECT CT procedure takes approximately 30 minutes. However, the nuclear radiologist may take additional images of specific regions to capture more detail.

Post SPECT CT instructions

•    Drink 1-1.5 liters of water 2-3 days after the examination to flush out radioactive tracer from the body.
•    Wash your hands thoroughly after using the toilet.
•    Avoid close contact with young children and pregnant women for 24 hours.
•    Normal activities can resume as usual.

SCAPHOID AT THE CARPAL BONES FRACTURE
(Image credit: www.siemens-healthineers.com)

Who should not undergo SPECT CT?

•    Pregnant women
•    Breastfeeding women
•    Thyroid hyperplasia associated with thyroid cancer

What are the side effects of SPECT CT?

Common side effects of SPECT CT include bleeding, bruising, swelling, and redness at the needle puncture site, or an allergic reaction to the radioactive tracer, which is very rare. SPECT CT is typically considered a safe diagnostic test with no significant side effects, lingering residuals, or long-term complications.

What are the benefits of SPECT CT?

• Accurate interpretation: SPECT CT can detect abnormalities in organs and body systems that other diagnostic imaging tests, such as CT, cannot. This enables nuclear radiologists to correctly interpret and diagnose diseases, resulting in an accurate, personalized treatment plan. This enables radiologists to correctly interpret and diagnose diseases, resulting in an accurate, personalized treatment plan.
• Minimally invasive: SPECT CT is a minimally invasive procedure involving the injection of a radioactive tracer into the body prior to the examination. There is no large surgical incision, and neither local anesthesia nor sedation are used. The examination is less painful, safe, and free of serious complications or side effects.
• Personalized treatment plan: SPECT CT provides clear and specific diagnostic results, allowing doctors to plan a personalized treatment plan, leading to effective and timely treatment.
• No overnight hospitalization: SPECT CT is an outpatient procedure; there is no need for an overnight hospital stay. The entire examination process takes half a day. The examinee can return home and resume normal daily activities as usual.
• Low-dose radiation: Unlike other diagnostic imaging exams, SPECT CT uses a lower radioactive tracer dose, typically the same amount of X-ray radiation used in general physical examinations, such as chest X-rays, making it a safe diagnostic imaging exam without causing any harm to the examinees.

How long does it take to get SPECT CT results?

Typically, after a SPECT CT procedure, the radiologist will take 2-3 days to a week to interpret the results before informing the examinee. The physician will use the results to plan a personalized treatment plan suitable for each patient.

SPECT CT at MedPark Hospital

Diagnostic Radiology Center at MedPark Hospital, Bangkok, Thailand, is supervised by seasoned teaching faculty radiologists, including radiation oncologists, intervention radiologists, and nucleologists (nuclear medicine physicians) with extensive experience both nationally and internationally, ready to provide seamless diagnostics for common conditions and high acuity conditions using state-of-the-art digital medical instruments, including Digital X-ray, PET CT, or SPECT CT, and other leading-edge medical equipment to ensure accurate diagnosis, fast results, and precise interpretation, leading to effective and systematic treatment, integrated with the close collaborative work of a multidisciplinary team of specialists to provide holistic intervention, enabling fast, safe, and consistent treatments, allowing patients to recover quickly, have healthy physical health, and live lives at their best.

FAQ

• What is the difference between SPECT and CT?
  SPECT is a nuclear medicine imaging modality involving radioactive tracers emitting gamma-ray energy photons given by injection, swallowing, or inhalation before capturing images to assess the function of the body's organs, tissues, and blood circulation, as well as to detect cancer or tumors. SPECT will display the abnormal results as bright areas on the mages.

CT, or computed tomography, is detailed imaging of the anatomical bodily structure with X-rays. CT scans reveal the size and location of organs, bones, and tissues while also screening for cancer or tumors. CT will display abnormal results in black and white spots.

Nuclear radiologists combine SPECT and CT images to generate detailed, clear, and accurate diagnostic images of the bodily anatomic structures.

• Other body organs can be examined by SPECT C
  • LUNG
    • Pulmonary embolism
    • Chronic obstructive pulmonary disease (COPD)
  • KIDNEY
    • Kidney function
    • Ureteral obstruction
    • Renal parenchyma
    • Kidney function test after kidney transplant (both children and adults)
  • THYROID and PARATHYROID GLANDS
    
    • Thyroid cancer
    • Hyperparathyroidism
  • GALLBLADDER AND LIVER 
    
    • Gallbladder and liver functions
    • Bile duct obstruction
    • Bile duct leaks
    • Bile formation and secretion
    • Gallbladder emptying its bile into the intestines