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Problems and Pitfalls

发布时间:2013-12-04 13:02:24  

Problems and Pitfalls in the

Interpretation of PET/CT

George Segall, M.D.

Stanford University

False Negative FDG PETHistology


Low-grade gliomaLow-grade lymphomaBronchoalveolar lung cancerHepatomaRenal cell carcinomaProstate cancer< 10 mmPost prandial scansHyperglycemia

> 150 mg/dL

Post Prandial Scan

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 ScanFasting: Euglycemia 6 hours Diabetes12 hours

04/2505/08? fed fasting

Fasting Scan in a Diabetic

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.


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)

Insulin Effect on FDG uptake

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)

False Positive FDG PETPhysiologic

Benign Neoplasm



Granuloma, sarcoid, rheumatoid


Prosthesis, grafts


Physiologic Uptake

FDG subcutaneous infiltration

Physiologic Uptake

Tonsillar Hyperplasia

Physiologic Uptake

Nakamoto. Radiology 2005;234;879-885

Physiologic Uptake: Brown Fat

Brown Fat

What is brown fat?

Methods to reduce FDG uptake




?Beta blockers??


74 yr old man with seizures and recent cognitive disorder


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


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

AdenomaAdrenal adenoma

SUV adrenal 4.0

SUV liver2.2

51 yr old man with colon cancer treated with rectosigmoid colectomy and adjuvant chemotherapy.


82 year old man with wt loss and liver mass

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

Question 1

The correct answer is

Gollub et al. Combined CT Colonography and 18F-FDG PET of Colon Polyps: Potential Technique for Selective Detection of Cancer and Precancerous Lesions. 2007 Jan;188(1):130-8.Friedland et al. 18-Fluorodeoxyglucose positron emission tomography has limited sensitivity for colonic adenoma and early stage colon cancer. Gastrointest Endosc. 2005 Mar;61(3):395-400.

d. All of the above

Nodular Hyperplasia

74 y/o man with metastatic disease to neck from

unknown primary, now NED after chemoXRT


68 year old man with solitary lung nodule.

Biopsy: aspergillosis

Granulomatous Disease

62 year old man with hilar and mediastinal

adenopathy. Biopsy: sarcoidosis

Miscellaneous Causes


Miscellaneous CausesRib Fracture

Problems with CTAttenuation and scatterBeam hardeningVolume averaging

Beam Hardening

Gollub et al. J Nucl Med 2007;48:1583-1591

Beam Hardening

Volume Averaging

Gollub et al. J Nucl Med 2007;48:1583-1591

Problems with PET/CTPatient movement

Respiratory misregistrationAttenuation correction

Patient MovementHead movementSecure head, or use head holder?

Respiratory Misregistration?Respiratory variation

Partial expiration best:

“Breathe in, exhale, don’t


from Ben Yeh MD, UCSF

Respiratory Misregistration

Sureshbabu and Mawlawi. J Nucl Med Technol 2005;33:156-161

Question 2

Respiratory misregistration in PET/CT is minimized when

a.CT is performed in end inspirationb. CT is performed in mid expirationc. CT is performed in end expiration

d. CT is performed during quiet breathing

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;33:156-161

Attenuation Correction

Sureshbabu and Mawlawi. J Nucl Med Technol 2005;33:156-161

Attenuation Correction

Sureshbabu and Mawlawi. J Nucl Med Technol 2005;33:156-161


?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


?CT artifacts can be avoided by optimizing technique

?PET/CT artifacts can be reduced by proper patient preparation and instructions

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