JHSGR16th April 2011
Dr Lee Man Kit Derek
The value of PET in staging adenocarcinoma (e.g. colorectal cancer) is well established
Tomoharu T. et al. The American J of Surg. 2002; 184: 433-436
Not as straight forward as other tumors in knowing where PET-CT fits into management
HCC accumulate FDG to varying degrees
Conventional F-FDG PET has a high average false-negative rate of 40-50% in the detection of HCC
Delbeke et al. Arch Surg. 1998;133:510-515Khan et al. J Hepatol. 2000;32:792-797
Okazumi et al. J Nucl Med. 1992;33:333-339
Questions to be answered:1. Ability to differentiate benign and
malignant liver lesions2. Detection of intra-hepatic tumors +/-
metastasis3. Detection of extra-hepatic metastasis
• Recent studies suggested the use of another tracer, C-acetate, in conjunction with F-FDG to increase the detection rate of HCC
• The degree of HCC differentiation determines its relative avidity for one of the two probe molecules
Ho et al.
F-FDG C-acetate
Well differentiated HCC - +
Poorly differentiated HCC
+ -
C-acetate is able to detect the entire proportion of HCC lesions that are negative on F-FDG imaging
Tumors that are both positive on C-acetate and F-FDG are taken up by different parts of tumors
Well differentiated HCC
Poorly differentiated HCC
Moderately differentiated HCC
Dual-tracers PET are complementary to each other in the detection of HCC
The addition of C-acetate to F-FDG PET-CT increases the overall sensitivity for the detection of primary HCC
Park et al.
F-FDG C-acetate Dual tracer
Sensitivity (%) 60.9 75.4 82.7
Dual-tracers PET can be quite specific for HCC (Ho et al.) Useful in the preliminary evaluation of unknown liver
massesC-acetate
F-FDG
+ + HCC is likely
- + Non HCC malignancy or poorly differentiated HCC
- - Benign pathology is more likely
Although dual-tracers PET has a high sensitivity in detecting HCC
Limitation in diagnosing small tumor (<2cm HCC)
Park et al.
Dual tracer PET-CT appear not to be useful for the detection of small lesions (<2cm) in the liver
Particularly useful when patients come in for post-op follow up Imaging of liver : no recurrence of tumor Alpha fetoprotein : ↑ trend
Extra-hepatic metastasis Lung Bone Adrenal gland Abdominal peritoneum Brain
F-FDG PET has only a fair sensitivity in diagnosis of primary HCC
Studies have reported that F-FDG PET may have its role in detection of HCC secondary tumors
Bohm et al. J Cancer Res Clin Oncol. 2004;130:266-272Sugiyama et al. J Gastroenterol. 2004;39:961-968
Dual-tracers PET can detect extra-hepatic metastatic tumor diameter >1cm For tumor 1-2cm, FDG is more sensitive than C-acetate,
although the difference is not statistically significant
For metastatic HCC, dual tracer PET-CT was not superior to FDG alone
I : Primary HCC FDG avidII : Primary HCC C-acetate avidIII : Primary HCC both tracers avidIV : no baseline PET for primary tumor characterisation
6 lesions both tracers avid
12 lesions both tracer avid
44 lesions both tracer avid
23% of metastatic lesions were detected by C-acetate only
NPV of single-tracer PET <50% Negative single-tracer cannot reliably exclude
metastatic HCC Dual-tracers PET had an incremental value when
compare with single-tracer PET in the evaluation of HCC metastasis
Questions to be answered: Ability to differentiate benign and
malignant liver lesions• Dual-tracers PET has high specificity for
detection of liver masses (benign vs malignant)
• F-FDG PET alone has poor sensitivity in detecting primary HCCThe addition of C-acetate to F-FDG PET
increases overall sensitivity
Questions to be answered: Detection of intra-hepatic tumors +/-
metastasis• Dual-tracer PET has the limitation in detecting
intra-hepatic HCC <2cm
• Other imaging modality i.e. Primovist ®-enhanced MRI can be used Able to detect small liver metastases (<1cm)
Kim et al. AJR Am J Roentgenol. 2009 Jun;192(6):1675-81
Questions to be answered: Detection of extra-hepatic metastasis
• F-FDG PET has a relatively high sensitivity for detection of extra-hepatic metastasis HCC
• Dual-tracer PET demonstrate complementary role in the detection of extra-hepatic metastasis HCC
PET-CT has to be seen as part of the work up and not a complete replacement of other imaging modalities for detecting HCC USG Triple phase multi-detector CT Primovist ®-enhanced MRI
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