Nuclear Medicine · MU Sofia

13. Application of FDG PET-CT in the diagnosis of tumors, staging, monitoring the effect of treatment and prognosis.

Covers the use of 18F-FDG PET/CT in tumour diagnosis, starting with the Warburg effect and its limits, then staging with TNM and lymph-node and distant metastasis detection, restaging and recurrence, and monitoring treatment response. It explains metabolic response categories, the Deauville five-point scale for lymphoma, RECIST versus PERCIST, SUV measures and factors affecting them, metabolic tumour volume, and prognosis. A comparison table and false-positive and false-negative causes are included.

Inside: 19 sections · 2 tables · 16 flashcards · 14 min

Topic 13 of 50 in the MU Sofia syllabus for Nuclear Medicine (Medicine, Year 4). The free AceMed note covers it in 19 sections, about 1,861 words (14 min of reading), with 16 flashcards.

In this note

  1. Topic 13: Application of FDG PET/CT in Tumor Diagnosis, Staging, Monitoring Treatment Effect and Prognosis
  2. PART I — APPLICATION IN TUMOR DIAGNOSIS
  3. Differentiation of Benign and Malignant Lesions
  4. Detection of an Unknown Primary Tumor
  5. Biopsy Guidance
  6. PART II — APPLICATION IN TUMOR STAGING
  7. Lymph Node Staging
  8. Detection of Distant Metastases
  9. Detection of Bone and Bone-Marrow Disease
  10. PART III — RESTAGING AND RECURRENCE DETECTION
  11. PART IV — MONITORING THE EFFECT OF TREATMENT
  12. TYPES OF METABOLIC RESPONSE
  13. RESPONSE ASSESSMENT IN LYMPHOMA
  14. METABOLIC RESPONSE VERSUS ANATOMICAL RESPONSE
  15. RECIST AND PET RESPONSE CRITERIA
  16. STANDARDIZED UPTAKE VALUE
  17. METABOLIC TUMOR VOLUME
  18. TREATMENT-SPECIFIC RESPONSE PATTERNS
  19. PART V — APPLICATION IN PROGNOSIS

Topic 13: Application of FDG PET/CT in Tumor Diagnosis, Staging, Monitoring Treatment Effect and Prognosis

18F-FDG PET/CT is a hybrid imaging technique combining:

  • PET — demonstrates tissue glucose metabolism.
  • CT — demonstrates anatomy and structural abnormalities.

The radiopharmaceutical used is: 18F-fluorodeoxyglucose. Explain mechanism

WARBURG EFFECT

The Warburg effect is the tendency of many malignant cells to use high levels of glycolysis even when sufficient oxygen is available.

This leads to:

  • Increased glucose consumption.
  • Increased FDG uptake.
  • Visualization of many tumors as “hot” lesions on PET.

However, FDG uptake is not exclusive to malignant cells.

PART I — APPLICATION IN TUMOR DIAGNOSIS

1. Detection of a Primary Tumor

FDG PET/CT can identify a metabolically active primary tumor.

A malignant lesion commonly appears as:

  • Focal increased FDG uptake.
  • Uptake greater than the surrounding background.
  • Corresponding abnormality on CT.

However, the intensity of uptake varies considerably among tumors.

2. Characterization of a Suspicious Lesion

PET/CT may help determine whether a lesion found on:

  • CT.
  • MRI.
  • Ultrasound.
  • Chest X-ray.

is metabolically active.

For example:

A pulmonary nodule is identified on CT.

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FDG PET/CT is performed.

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Marked focal FDG uptake increases suspicion of malignancy.

However, tissue diagnosis may still be required because infection and inflammation can also be FDG-avid.

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