JHSGR 16 th 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:

 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: Khan et al. J Hepatol. 2000;32: Okazumi et al. J Nucl Med. 1992;33:

Questions to be answered: 1. Ability to differentiate benign and malignant liver lesions 2. Detection of intra-hepatic tumors +/-metastasis 3. 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-FDGC-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-FDGC-acetateDual tracer Sensitivity (%)

 Dual-tracers PET can be quite specific for HCC (Ho et al.)  Useful in the preliminary evaluation of unknown liver masses C-acetateF-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: Sugiyama et al. J Gastroenterol. 2004;39:

 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 avid II: Primary HCC C-acetate avid III: Primary HCC both tracers avid IV: 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 HCC The 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 Jun;192(6):

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