Tc-99m PMT hepatobiliary scintigraphy in the differential diagnosis of extrahepatic metastases and hepatocellular carcinoma

¹⁸F-FDG PET/CT in hepatocellular carcinoma: detection of bone metastasis and prediction of prognosis

OBJECTIVE

The purpose of this study was to assess the diagnostic accuracy and prognostic value of 18F-fluorodeoxyglucose PET/computed tomography (CT) in bone metastases from hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Of 3912 consecutive HCC patients, 67 patients who had undergone both PET/CT and bone scintigraphy (BS) within a 3-month interval were evaluated.

RESULTS

Bone metastases were most frequently found in the pelvis (20%), followed by the lumbar spine (14%) and long bones (13%). PET/CT was significantly more sensitive than BS in region-based analyses, with 273 confirmed bone metastases (96.7 vs. 52.7%, respectively; P<0.001), and in patient-based analyses (99 vs. 85%; P=0.042). The median survival period was 5 (range, 0.4-18) months. On univariate analysis, poor prognostic factors included age (<60 years), multiple bone metastases, lymph node metastasis, high serum α-fetoprotein (≥400 IU/ml), Child-Pugh class B, and high maximum standardized uptake value (SUVmax) of bone metastasis (>5.0). Large metabolic volume (≥200 cm3) of bone metastasis was another poor prognostic factor. On Cox regression analysis, high α-fetoprotein was the only poor prognostic factor with statistical significance.

CONCLUSION

PET/CT was more sensitive than BS in bone metastasis from HCC by both patient-based and region-based analyses, and offered additional information on survival. PET/CT can be helpful in early diagnosis and opportune treatment of bone metastasis from HCC.

99mTc-DISIDA uptake in liver lesion and pulmonary metastases shown on SPECT/CT in a patient with hepatocellular carcinoma

A 43-year-old man, previously submitted to right hepatectomy, right hepatic artery chemoembolization, and surgical resection of liver lesions, with well-differentiated and moderately differentiated hepatocellular carcinoma (HCC) confirmed by histopathology, underwent cholescintigraphy with Tc diisopropyliminodiacetic acid (Tc-DISIDA) due to recurrent cholangitis. The scintigraphic images and the coregistered CT images showed radiotracer uptake in an area of biliary ectasia near the hepatic surface (which may be associated with recurrent cholangitis), in a hepatic nodule, and in multiple pulmonary metastases.

Molecular imaging of hepatocellular carcinoma

Molecular imaging may be defined as spatially localized and/or temporally resolved sensing of molecular and cellular processes in vivo. An imageable molecular event may be the result of the overexpression of a gene that produces a specific messenger RNA. The overexpressed protein could be an enzyme or could be incorporated into cell-surface transporters or receptors. Any step of this process is a potential target for molecular imaging. Current molecular imaging modalities include magnetic resonance imaging, nuclear imaging, ultrasound, and optical imaging. Nuclear medicine has been at the forefront of molecular imaging because of the relatively high sensitivity to detect nanomolar or picomolar quantities of the radiolabeled imaging probe. Imaging has had a central role in the diagnosis of hepatocellular carcinoma (HCC), which is considered the fifth most frequent malignancy worldwide. Nuclear imaging was one of the earlier modalities used for liver imaging. Traditional tracers included technetium 99m ( 99m Tc) sulfur colloid, gallium 67, and 99m Tc iminodiacetate acid analogues. Other less traditional probes include 99m Tc diethylenetriamine pentaacetic acid-galactosyl-human serum albumin for evaluation of functional liver volume and 99m Tc-labeled tetrofosmin and methoxisobutylisonitrile for detecting drug resistance. Fluorodeoxyglucose is the most widely used probe for positron emission tomography (PET) tumor imaging; however, carbon 11-labeled acetate appears to show improved sensitivity and specificity for HCC. Oxygen 15 PET imaging allows for the measurement of hepatic and tumor blood flow. Difficulties developing specific imaging methods for HCC are caused by the lack of obvious specific molecular targets, problems with drug delivery, and poor contrast-to-noise. No magic molecular imaging method exists today to accurately detect, characterize, and monitor HCC in vivo.

Recent advances in imaging hepatocellular carcinoma: diagnosis, staging and response assessment: functional imaging

Historically, nuclear medicine has had an important role in the differential diagnosis of liver tumors but has been largely superseded by other forms of conventional imaging, in particular computed tomographic portography. It remains helpful in difficult cases because it has characteristic features in both hepatocellular carcinoma (HCC) and benign conditions. 131I is an important therapeutic tool. FDG-PET is useful in certain cases, especially for finding metastases and monitoring response to therapy.