Breast cancer with low FDG uptake: characterization by means of dual-time point FDG-PET/CT.

BACKGROUND: Malignant breast lesions usually are differentiated by FDG-PET with a semiquantitative FDG standardized uptake value (SUV) of 2.5. However, the frequency of breast cancer with an SUV of less than or equal to 2.5 is noteworthy, and often present diagnostic challenges. This study was undertaken to evaluate the accuracy of dual-time point FDG-PET/CT with FDG standardized uptake value (SUV) calculation in the characterization of such breast tumors. METHODS: Forty-nine female patients with newly diagnosed breast cancer were found to have primary breast cancer with minimally increased FDG uptake and met the criteria for inclusion in this study by having borderline levels of increased FDG uptake (SUV max less than or equal to 2.5) in the initial FDG-PET/CT images. Consequently, they underwent further delayed phase FDG-PET/CT scan for better evaluation of the disease. RESULTS: Of the 49 cancer lesions; the majority were found to have rising or unvarying dual-time changes in SUV max (75.5%). The median value of SUV max increases by 25% between the early and delayed scan. The means+/-S.D. of the SUV max1, the SUV max2, and the Delta SUV max% were 1.2+/-0.6%, 1.3+/-0.9%, and 5.1+/-22.4%, respectively. The receiver-operating-characteristic (ROC) analysis proved that the highest accuracy for characterization of malignant breast lesions was obtained when a Delta SUV max% cut-off value 0.0% was used as criteria for malignant FDG uptake-change over time with sensitivity 75.5%, and false-positive rate 20.4%. CONCLUSION: These results suggested that dual-time FDG-PET/CT imaging with standardized uptake value (SUV) estimation can improve the accuracy of the test in the evaluation of breast cancer with low FDG uptake.

Positron emission tomography and breast lesions: low FDG activity in early phase imaging is not essentially benign.

The frequency of malignancy with low FDG uptake is significant and often presents diagnostic challenges. The usefulness of dual-time point FDG-PET/CT imaging (including early "after 45 minutes" and delayed "after 100 minutes," phases after radionuclide administration) for detection of such tumors has been documented. The authors present 2 cases of pathologically proven breast cancer with minimally increased FDG uptake on the initial scan (maximum standardized uptake value; SUVmax <2.5). Detection was improved by performing a dynamic PET study with early and delayed scans. Patients with a poorly visualized breast lesion due to minimal FDG uptake on the initial FDG-PET images should not be considered as benign and deserves further delayed phase imaging.

Recurrence-free survival after radiofrequency ablation of hepatocellular carcinoma. A registry report of the impact of risk factors on outcome.

BACKGROUND: Despite the high complete necrosis rate of radiofrequency ablation (RFA), tumor recurrence, either local tumor recurrence or new tumor formation, remains a significant problem. Purpose of this study is to evaluate the pattern and risk factors for intrahepatic recurrence after percutaneous RFA for hepatocellular carcinoma (HCC). METHODS: We studied 40 patients with 48 HCCs (< or = 3.5 cm) who were treated with percutaneous RFA. The mean follow-up period was 24.1 +/- 15.7 months. We evaluated the cumulative disease-free survival of overall intrahepatic recurrence, local tumor progression (LTP) and intrahepatic distant recurrence (IDR). Thirty host, tumoral and therapeutic risk factors were reviewed for significant tie-in correlation with recurrence: age; gender; whether RFA was the initial treatment for HCC or not; severity of liver disease; cause of liver cirrhosis; contact of tumor to major hepatic vessels and liver capsule; degree of approximation of tumor to the liver hilum; ablation time; degree of benign pre-ablational enhancement; sufficient safety margin; tumor multinodularity; tumor histological differentiation; tumor segmental location; maximum tumor diameter; degree of tumor pre-ablational enhancement at arterial phase CT, MRI or CT-angiography; and laboratory markers pre- and post-ablation (AFP, PIVKA II, TP, AST, ALT, ALP and TB). RESULTS: The incidence of overall recurrence, LTP and IDR was 65, 23 and 52.5%, respectively. The cumulative disease-free survival rates were 54.6, 74.8 and 78.3% at 1 year, 27.3, 71.9 and 46.3% at 2 years and 20, 71.9 and 29.4 at 3 years, respectively. Univariate and multivariate analysis showed that the significant risk factors for LTP were: tumor size > or = 2.3 cm, insufficient safety margin, multinodular tumor, tumors located at segments 8 and 5, and patient's age > 65 years (P < 0.05). No significant risk factor relationship for IDR could be detected. CONCLUSION: Our results would have clinical implications for advance warning and appropriate management of patients scheduled for RFA. Patients at risk of LTP should be closely monitored in the first year. Furthermore, regular long-term surveillance is essential for early detection and eradication of IDR.