Positron Emission Tomography / CT
Combines metabolic imaging with CT anatomy for cancer staging and therapy response.
What is PET-CT?
PET-CT injects a radiotracer (commonly FDG) to map metabolic activity, fused with CT for localization.
How it works: The tracer accumulates in metabolically active tissue; PET detects gamma photons and CT provides attenuation correction and anatomy.
Common Uses of PET-CT
Oncology staging/restaging
Detect nodal and distant metastases with whole-body survey capability.
Therapy response
Measure metabolic response to chemo/immunotherapy within weeks.
Occult infection/inflammation
Identify fever of unknown origin or vasculitis.
Advantages
- ✓Whole-body survey of disease activity
- ✓Quantitative SUV metrics
- ✓Anatomical localization via CT
- ✓Early detection of treatment response
- ✓Single-session comprehensive assessment
Limitations
- ⚠Higher cost and radiation dose
- ⚠False positives in inflammation
- ⚠Requires fasting and glucose control
- ⚠Limited in brain evaluation
- ⚠Artifacts from metallic implants
Preparation Checklist
0 of 3 completed
⚖️PET-CT vs CT
Related Imaging Modalities
MRI provides superior soft tissue detail without radiation; PET-MRI reduces radiation dose; CT alone offers faster, lower-cost anatomical imaging; US provides real-time guidance without contrast.
CT
CT scans use X-rays to create detailed cross-sectional images of the body. They are particularly useful for detecting bone fractures, tumors, and internal bleeding.
MRI
MRI uses powerful magnets and radio waves to produce detailed images of organs and soft tissues. Excellent for brain, spine, and joint imaging.
Ultrasound
Ultrasound uses sound waves to create real-time images. Commonly used for pregnancy monitoring and examining organs like the heart, liver, and kidneys.
Frequently Asked Questions
Find answers to common questions about this imaging modality.
Browse PET-CT Terms
Explore common terms in PET-CT reports, each with detailed explanations, clinical significance, and related lab tests to help you understand your imaging results. lab tests.
Colorectal Cancer PET-CT: What It Shows, Cost & Preparation
FDG-avid primary tumor (SUVmax typically 5-15), metastatic lesions in liver/lungs/lymph nodes. Normal colon shows mild physiologic uptake, but focal intense uptake suggests malignancy.
Lung Cancer Staging on PET-CT: What It Shows, Cost & Prepara
FDG-avid (hypermetabolic) lesions correlated with anatomic CT findings. Primary lung mass, lymph node involvement, distant metastases to liver, bone, adrenal glands, or brain.
Lymphoma PET-CT: What It Shows, Cost & Preparation
FDG-avid lymphadenopathy with SUVmax typically 5-20 for Hodgkin lymphoma, 3-15 for NHL. Diffuse splenic uptake in splenic involvement. Bone marrow infiltration shows diffusely increased marrow activity.
Melanoma PET-CT: What It Shows, Cost & Preparation
FDG-avid lesions with variable SUVmax (typically 2-10 for primary lesions, higher for metastases). Pattern includes primary skin lesion, in-transit metastases, lymph node involvement, and distant visceral metastases.
Lung Cancer Staging PET-CT: What It Shows, Cost & Preparatio
Focal increased FDG uptake in primary tumor, potential metastatic lymph nodes, and distant metastases
Solitary Pulmonary Nodule PET-CT: What It Shows, Cost & Prep
Variable FDG uptake depending on nodule etiology; malignant nodules typically show intense uptake
Treatment Response PET-CT (PERCIST): What It Shows, Cost & P
Changes in FDG uptake (SUV) compared to baseline; complete/partial metabolic response, stable disease, or progressive metabolic disease
Head and Neck Cancer PET-CT: What It Shows, Cost & Preparati
FDG-avid primary tumor with potential regional nodal and distant metastases; post-treatment assessment for residual/recurrent disease
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