Chapter 1: The science and the scan

"Boring, But Necessary"

1. What is a PET/CT Scan?

Hybrid Imaging System
Anatomic & Functional Exam
The Machine
“Whole Body” vs. “Skull Base to Mid-Thigh”
Three Sets of Images
Produced

2. Basic Science 18F-FDG

Glucose Analog
Malignancy & Glucose Metabolism
Mechanisms for Increased Intracellular Glucose
Why 18F-FDG Works

3. Power of PET/CT

Whole Body Assessment
The “You’re Kidding Me!” Effect
Post-Therapeutic Scar vs. Active Malignancy

4. Indications for PET/CT

Detecting Malignancy
Staging Malignancy
Assess Response to Therapy
Detecting Recurrence

5. The Limitations of PET/CT

Not All Cancer is FDG-Avid
Normal FDG-Uptake vs. Pathologic Uptake
Technical Limitations
- Poor Patient Preparation
- Misregistration
- Brown Fat Activation
- SUV Problems
- Fields of View Discrepancy
- PET/CT Artifacts
- Timing of Exam After Therapy

6. Images Generated

CT Images
Non-Attenuation Corrected Images
Attenuation Corrected Images
Maximum Intensity Projection (MIP)
Fusion of Images
All Images Viewed in 3 Planes

7. Contrast Media: Oral & I.V.

Who Gets Oral Contrast?
Who Gets IV Contrast?
Oral Contrast “Cocktail” Recipe

8. What the Patient Should Expect

Documenting Height & Weight
Private Resting Room
Drinking PO Contrast
FDG Injection
Delay Between Injection & Scan

9. Safety Concerns with PET/CT Imaging

Radiation Exposure to Patient
Radiation Exposure to Patient’s Contacts
Patient Contact with Pregnant Women
Breastfeeding

Chapter 2: PET/CT Problems Which Limit Interpretation

"Something just doesn't seem right here"

1. Poor Patient Preparation

Optimizing Glucose & Insulin Levels
- Fasting Prior to Exam
- Diabetic Patients
- Low Carbohydrate Diet
- Hydration
Strenuous Exercise
Voiding Prior to Exam
Patient Instruction Sheet

2. Brown Fat

Definition
Distribution / Appearance
Don’t Miss the Hidden Nod
Reporting Language
Prevention

3. Timing of PET/CT Exam After Therapy

“Rule of 3”
- Chemotherapy: 1 month
- Surgery: 2 months
- Radiation: 3 months

4. Misregistration

Etiology: Hybrid Imaging
Patient Movement
Respiratory Motion
Breathing Techniques
Bowel Peristalsis

5. Extravasation of FDG

False Positives
False Negatives
Reporting Language

6. PET/CT Artifacts

Beam Hardening
Diaphragmatic Mismatch
Linear Hand Motion
Attenuation Correction
Differing Fields of View

7. The “Sponge Effect”

Poor Patient Preparation
FDG Extravasation
Extensive Brown Fat
Metformin-Induced Bowel Uptake
Marked Reactive Marrow Uptake
Extensive Tumor Uptake in

8. SUV Complications

Different Types of SUV Measurements
Factors that Influence SUV Measurements
What SUV Number Indicates Malignancy?
What Percent Change in SUV on a Follow Up Exam is Significant?
How to Compare Exams With Very Different Background Metabolic Activities?

Chapter 3: The Standardized Uptake Value (SUV)

"The good, the bad & the ugly"

1. What is the SUV & Why Used?

Quantitative vs. Qualitative Assessment
Unitless Measurement
Formula
SUV = ?

2. Variables that Affect SUV

Patient Preparation
Time Between FDG Injection & Scan
Partial Volume Effects
Extravasation
Patient Weight
Size & Position of ROI
Attenuation Correction Artifacts

3. Types of SUV Calculations

Consensus?
Body Weight
Lean Body Mass
Ideal Body Weight
Body Surface Area
Maximum vs. Mean
Average SUV’s by Organ

4. Interpreting the SUV: Threshold Values, “Oncologic Plausibility” & Relative Uptake

Precise Threshold Values?
“Oncologic Plausibility”
Relative Uptake
Assessing Nodes in Lymphoma Cases
Assessing Nodes in Non-Lymphoma Cases
Potential Lesions in Solid Organs
Pulmonary Nodules

5. What % Change in SUV on a Follow Up Exam is Clinically Significant?

The Problem
Current Recommendations

6. How to Compare Sequential Exams With Very Different Background Activities?

Differing Background Metabolic Activities
When Qualitative Assessment is Required
Reporting Language

7. Should We Just Abandon the SUV?

Pros & Cons
“Qualitative” Definitions
- Mild
- Moderate
- Intense
Final Recommendations

Chapter 4: Our Systematic Approach to Reading a PET/CT

"Eat your vegetables"

1. Reading Station & Reading Software

Reading Station
Monitor Set-Up
PET/CT Reading Software
Hanging Protocol

2. General Reading Caveats

Reading in Context (“Oncologic Plausibility”)
Measure Size on CT, Not on PET Images
Abnormality Seen Only on First PET Image
Assess the Patient’s Main Pathology Last
Beware the Ureter

3. Excellent Views: The MIP, Coronal & Sagittal Images

3-D Rotating MIP & Coronal “Quick MIP”
Coronal PET
Sagittal PET

4. Written Annotations While Reading

Numbers, Numbers & More Numbers
Size & SUV Annotation System
Sample Annotation Sheet

5. The Language of Reporting

Goals of Reporting
Lawyers, Lawyers & Lawyers
Sample PET/CT Report
- Negative Exam
- Positive Exam
Patient Questionnaire
Technologist’s Data Sheet

6. The Read

Huge Exam: Requires Systematic Approach
Our “12-Step Reading System”
“The Read” in Action: Sample Case (Video)
Annotations for Sample Case
Final Report for Sample Case

Chapter 5: Normal Physiologic Distribution of FDG

"The essentials"

1. Introduction

To Locate Cancer, First Eliminate:
- Normal FDG-Avid “Structures”
- Benign FDG-Avid “Findings”

2. Head & Neck

3. Chest

4. Abdomen

5. Pelvis

6. Miscellaneous

Spinal Cord

The spinal cord typically demonstrates either minimal or no metabolic activity. Mild and even moderate patchy FDG uptake in the cord, however, is still considered to represent normal physiologic uptake (in the absence of an associated CT abnormality).

Any true focus of intense uptake within the spinal cord, however, is highly suspicious for malignancy and requires further assessment — especially as most spinal cord lesions are not visible on the co-registered non-contrast CT images.

In such cases, we report:

“A subcentimeter focus of intense metabolic activity projects within the spinal canal at the T8 level (SUV 3.2). Although an associated lesion is not clearly identified on the co-registered CT images, the appearance is highly suspicious for malignancy. MRI correlation is strongly recommended in this case.”