This document discusses the use of PET/CT imaging in chest imaging. It begins by explaining the Warburg effect, where cancer cells rely more on glycolysis than oxidative phosphorylation. PET/CT imaging takes advantage of this effect by using 18F-FDG, which is taken up by glycolytic cancer cells and detected by PET. The document then presents three case studies where PET/CT altered patient management by detecting unknown cancers or metastatic disease not seen on other imaging. It concludes that multiple studies have shown PET/CT can identify unexpected metastases in 10-20% of NSCLC patients and is more accurate than CT for staging lung cancer.

1. PET.CT in Chest Imaging
Thomas F. Heston, MD, FACNM, FASNC, FAAFP

2. Why PET/CT Works:
The Warburg Effect
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Normal Cells
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Low rate of glycolysis
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Aerobic metabolism
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Most Cancer Cells
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High rate of glycolysis
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Anaerobic metabolism

3. Imaging Glycolysis: 18-F FDG

4. Imaging the glycolisis: Positron Emission Tomography
511 γ
e+
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511 γ

5. Imaging the Warburg Effect: Why it Works

6. The Warburg Effect: Cancer Types
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Nearly all solid tissue tumors
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Lung
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Colon
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Breast
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Notable Exceptions
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Slow growth: prostate cancer (use 18F-fluoride)
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Mucinous: BAC
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Early Disease: tumors < 0.5 cm

8. 18-F FDG PET/CT Works Because:
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Tumor cells have increased glycolysis
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O-18 enriched water bombarded by protons
---> F-18 ---> 18F-FDG
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FDG hits a metabolic dead end
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PET images 18F positron emissions
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CT allows anatomic localization

9. Imaging the Warburg Effect: Normal vs Abnormal

10. Case Studies

11. Case #1: SCLC
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71 yr F with SCLC.
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Conventional staging
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Lung tumor
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Suggestive left lung nodes
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Suggestive liver metastases

12. Used with permission: Mike Medeiros, Chief Technologist, Western Washington Oncology, Lacey, WA

13. Used with Permission: Mike Medeiros, Chief Technologist, Western Washington Oncology, Lacey, WA

14. Case #1: How PET Helped
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PET/CT Findings
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Identified unknown contralateral disease
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Identified unknown skeletal metastases
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Conclusively identified “suggestive” findings
on CT as metastatic disease
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Conclusion: FDG PET/CT important in
staging SCLC

15. Case #2: Lung Mass
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77 yo F with remote hx of TB
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Conventional imaging (CT) noted the
lung mass and indeterminate liver
lesions
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An FDG PET scan was then performed

16. Case #2: CT Scan
Used with permission: Dr. Gabriel Soudry, petcases.com

17. Case #2: PET Scan
Normal FDG
uptake with no
evidence of
malignancy
Used with permission: Dr. Gabriel Soudry, petcases.com

18. Case #2: How PET Helped
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On the basis of the PET scan and
clinical circumstances, no further
testing was performed and invasive
procedures avoided.

19. Case #2: Evidence Base
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Meta-analysis of 1474 pulmonary
lesions
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FDG PET sensitivity 96.8%
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High negative predictive value
Reference: JAMA 2001;285:914-924

20. Case #3: Lung Nodule
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77 yo F being followed with serial CT
for a lung nodule
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CT Findings
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Initial: 6mm nodule
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6 mo follow-up: 6mm nodule
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No other abnormalities identified
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PET Scan then performed

21. Case #3: CT Findings
Baseline
6-mo f/u
Used with permission: Dr. Gabriel Soudry, petcases.com

22. PET Scan:
a) FDG avid nodule
b) Large hilar FDG
avid mass which
was only seen
retrospectively on
CT
Used with permission: Dr. Gabriel Soudry, petcases.com

23. Case #3: How PET Helped
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PET outperformed wait & watch
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No FNA of nodule necessary
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FNA: low yield for a 6 mm nodule
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FNA: high false negative rate
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FNA: added morbidity

24. Case #3: Evidence Base
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PET Sens 97% and Spec 78% (1)
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PET often alters management
compared to CT (2)
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41% upstaged
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20% downstaged
References: (1) JAMA 2001;285:914-924, (2) N Engl J Med
2000;343:254-61

25. PET/CT Bone Scans

26. F-18 NaF vs Tc-99m MDP
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PET/CT more accurate
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Sensitivity: 90% vs 80%
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Specificity: 95%+ vs 90%
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PET/CT more comfortable
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Shorter uptake time
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Shorter scan time

27. PET/CT vs SPECT
http://www.cms.gov/mcd/publiccomment_popup.asp?comment_id=19917

28. Dual Tracer Acquisition

29. Research Studies

30. Staging NSCLC by PET
Ann Thorac Surg 1995;60:1573
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99 patients: 67 for staging NSCLC and 32 with a
nodule subsequently determined to be NSCLC
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Unexpected distant metastatic disease in 11
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CT false-positive for metastatic disease in 18
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Conclusion: FDG PET plays an important role in
staging NSCLC

31. Detection of Unexpected Extrathoracic
Metastases in NSCLC With PET
Langenbecks Arch Chir Suppl Kongressbd. 1998;115:1264-7
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100 patients with stage IIIa or less NSC lung
cancer by conventional imaging
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Unexpected distant metastatic disease in 13
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Conclusion: FDG PET plays an important role in
staging NSCLC

32. FDG PET in Staging Lung Cancer
Ann Thorac Surg 1999;67:790-797
• 97 NSCLC patients under consideration for surgery
• PET found that 16/97 patients had unexpected
distant metastatic disease
• PET results altered management in 35/97
• CONCLUSION: FDG PET plays an important role in
appropriately staging NSCLC patients

33. Preoperative Staging of NSCLC With PET
NEJM Volume 343:254-261 July 27, 2000
• 102 patients with suspected resectable NSCLC
• unexpected distant metastatic disease was found in
11/102
• PET altered cancer stage in 62/102
• CONCLUSION: FDG PET plays an important role in
appropriately staging NSCLC patients

34. Clinical Impact of FDG PET in NSCLC
J Clin Oncol. 2001 Jan 1;19(1):111-8
• prospective trial of 105 NSCLC patients
• 12 patients considered inoperable were downstaged
• 27 patients were upstaged to palliative treatment
• PET changed therapy in 67% of patients
• CONCLUSION: FDG PET plays an important role in
appropriately staging NSCLC patients

35. Detecting Unsuspected Distant Metastases
by PET in Apparent Stage III NSCLC
Int J Radiat Oncol Biol Phys. 2001 Jun 1;50(2):287-93
• 137 NSCLC patients
• Unexpected distant metastatic disease found in
32/137
• CONCLUSION: FDG PET plays an important role in
appropriately staging NSCLC patients

36. CONCLUSION
• FDG PET improves surgical outcomes by
decreasing the futile thoracotomy rate
– FDG PET identifies unexpected metastatic
disease in 10% to 20% of NSCLC patients
– FDG PET is the most sensitive, specific, and
accurate imaging modality to stage the
mediastinum
• FDG PET is both downstages and upstages NSCLC

37. QUESTIONS
• When should a less sensitive, less specific,
less accurate test be preferable to a
more sensitive, more specific, more
accurate test? (CT versus PET)
• Don’t all patients with NSCLC deserve the
most accurate staging possible?

38. CONCLUSIONS
• For the SPN
– FDG PET allows a faster decision on
whether to follow by serial CT scans
or to proceed to invasive diagnosis
– FDG PET is the most sensitive,
specific, and accurate imaging test
available

39. CONCLUSIONS
• For confirmed or suspected NSCLC
– FDG PET has been shown in multiple
studies to identify unsuspected
distant metastatic disease in 10% to
20%
– FDG PET is more sensitive, specific,
and accurate in staging the
mediastinum compared to CT

40. FDG PET/CT vs MDP Bone Scan - 1
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70 pts with a variety of cancers with bone mets
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Per Patient Basis: PET/CT 97% vs BS 86% sensitivity
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Per Lesion Basis: PET/CT 92% vs BS 70% sensitivity
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Incidental Findings: in 24 patients, organ metastases
were found and in 7/7 pts with unknown primary, the
primary was found
Ozülker T, Küçüköz Uzun A, Ozülker F, Ozpaçac T. Comparison of (18)F-FDG-PET/CT with (99m)Tc-MDP
bone scintigraphy for the detection of bone metastases in cancer patients. Nucl Med Commun. 2010
Jun;31(6):597-603.

41. FDG PET/CT vs MDP Bone Scan - 2
MDP - Equivocal PET/CT - Definite
Ozülker T, Küçüköz Uzun A, Ozülker F, Ozpaçac T. Comparison of (18)F-FDG-PET/CT with (99m)Tc-MDP
bone scintigraphy for the detection of bone metastases in cancer patients. Nucl Med Commun. 2010
Jun;31(6):597-603.

42. Clinical Guidelines

43. 2007: American College Chest
Surgeons
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SPN: yes
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NSCLC: yes for patients being treated
with curative intent

44. 2008: JNM Consensus Panel
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Diagnosis of SPN: yes
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Staging NSCLC: yes
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Staging SCLC: uncertain
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Restaging: no opinion

45. 2009: Irish Thoracic Society
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Any time resection is being
considered
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Characterization of pulmonary
nodules (selected cases)

46. 2010: NCCN
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SPN: yes
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NSCLC Staging: yes
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Radiation Therapy Planning: yes

47. Questions?
Tawam Molecular Imaging Centre

48. Thank You!