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George Segall, M.D. Stanford University Problems and Pitfalls in the Interpretation of PET/CT.

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Presentation on theme: "George Segall, M.D. Stanford University Problems and Pitfalls in the Interpretation of PET/CT."— Presentation transcript:

1 George Segall, M.D. Stanford University Problems and Pitfalls in the Interpretation of PET/CT

2 False Negative FDG PET Histology Size Post prandial scans Hyperglycemia Low-grade glioma Low-grade lymphoma Bronchoalveolar lung cancer Hepatoma Renal cell carcinoma Prostate cancer < 10 mm > 150 mg/dL

3 57 year old man with stage IV left tonsillar scca treated with chemoradiation 21 months ago. Patient was lost to follow-up until he was referred for PET/CT. Coronal images show low FDG uptake in the brain, and high uptake in the heart and skeletal muscles. Post Prandial Scan

4 Fasting: Euglycemia 6 hours Diabetes 12 hours fed 04/25 fasting 05/08 Post Prandial Scan

5 51 year old man with colon polyps and a stricture referred for PET/CT to evaluate for possible malignancy. Fasting blood glucose level = 289 mg/dL. Coronal images show a good quality scan with normal FDG biodistribution. Fasting Scan in a Diabetic

6 69 year old man with 2.3 cm RUL NSC lung cancer. FBS = 309 mg/dL. No insulin was given. Coronal images show a good quality scan with high FDG tumor uptake (max SUV 5.4) Hyperglycemia

7 63 year old man with 5 cm RUL adenocarcinoma. FBS = 299 mg/dL; 90 minutes after 15u of reg insulin IV FBS = 179 mg/dL at which time FDG was injected. Coronal images show a “muscle scan” with faint tumor uptake (max SUV = 2.0) Insulin Effect on FDG uptake

8 False Positive FDG PET Physiologic Benign Neoplasm Inflammatory Miscellaneous Adenoma Granuloma, sarcoid, rheumatoid Prosthesis, grafts Fractures

9 Physiologic Uptake FDG subcutaneous infiltration

10 Physiologic Uptake Tonsillar Hyperplasia

11 Talking Nakamoto. Radiology 2005;234; Physiologic Uptake

12 Physiologic Uptake: Brown Fat

13 Brown Fat What is brown fat? Methods to reduce FDG uptake Heat Reassurance Sedatives Beta blockers

14 74 yr old man with seizures and recent cognitive disorder Adenoma

15 70 yr old man 2 months post chemoXRT for R piriform sinus cancer stage 3, T3N2M0. Adenoma

16 63 y/o man 4 months post chemoXRT for R tonsil cancer T2N1M0 Adenoma

17 51 yr old man with colon cancer treated with rectosigmoid colectomy and adjuvant chemotherapy. SUV adrenal 4.0 SUV liver2.2 Adenoma Adrenal adenoma

18 Adenoma 82 year old man with wt loss and liver mass

19 Question 1 Which of the following neoplasms have been associated with focal FDG uptake in the colon? a.Hyperplastic polyp b. Adenomatous polyp c. Adenocarcinoma d. All of the above

20 Question 1 Gollub et al. Combined CT Colonography and 18F-FDG PET of Colon Polyps: Potential Technique for Selective Detection of Cancer and Precancerous Lesions. AJR Am J Roentgenol Jan;188(1):130-8.AJR Am J Roentgenol. d. All of the above The correct answer is Friedland et al. 18-Fluorodeoxyglucose positron emission tomography has limited sensitivity for colonic adenoma and early stage colon cancer. Gastrointest Endosc Mar;61(3):

21 Nodular Hyperplasia 74 y/o man with metastatic disease to neck from unknown primary, now NED after chemoXRT

22 Infection 68 year old man with solitary lung nodule. Biopsy: aspergillosis

23 Granulomatous Disease 62 year old man with hilar and mediastinal adenopathy. Biopsy: sarcoidosis

24 Miscellaneous Causes Thyroiditis

25 Miscellaneous Causes Rib Fracture

26 Problems with CT Attenuation and scatter Beam hardening Volume averaging

27 Beam Hardening Gollub et al. J Nucl Med 2007;48:

28 Beam Hardening

29 Volume Averaging Gollub et al. J Nucl Med 2007;48:

30 Problems with PET/CT Patient movement Respiratory misregistration Attenuation correction

31 Head movement Secure head, or use head holder Patient Movement

32 Respiratory variation from Ben Yeh MD, UCSF Partial expiration best: “Breathe in, exhale, don’t breathe” Respiratory Misregistration

33 Sureshbabu and Mawlawi. J Nucl Med Technol 2005;33:

34 Question 2 Respiratory misregistration in PET/CT is minimized when a.CT is performed in end inspiration b. CT is performed in mid expiration c. CT is performed in end expiration d. CT is performed during quiet breathing

35 Question 2 The correct answer is b. CT is performed in mid expiration Sureshbabu W, Mawlawi O. PET/CT Imaging Artifacts. J Nucl Med Technol 2005;33:

36 Attenuation Correction Sureshbabu and Mawlawi. J Nucl Med Technol 2005;33:

37 Attenuation Correction Sureshbabu and Mawlawi. J Nucl Med Technol 2005;33:

38 Summary False negative FDG PET can be reduced by careful patient selection for appropriateness and proper preparation False positive FDG PET can be reduced by correlation with CT and knowledge of potential pitfalls

39 Summary CT artifacts can be avoided by optimizing technique PET/CT artifacts can be reduced by proper patient preparation and instructions

40


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