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TORONTO HEPATOCELLULAR CARCINOMA SCREENING PROTOCOL (THSP): ANALYSIS OF 3 MODALITY APPROACH TO WORKUP OF SMALL OR INDETERMINATE LESIONS DETECTED AT SCREENING FOR HCC
K Khalili*1, T-K Kim1, H-J Jang1, M Haider1, M Sherman2
1Medical Imaging, University Health Network, Toronto; 2Gastroenterology
BACKGROUND: The Toronto Hepatocellular carcinoma Screening Protocol (THSP) is a systematized clinical workup protocol of patients at risk for hepatocellular carcinoma based on modified AASLD guidelines.
OBJECTIVES: The aim is to assess contribution of 3 modality (CT, Contrast enhanced ultrasound (CEUS), and MRI) approach in lesion assessment.
METHODS: A clinical protocol for workup of liver lesions found at screening for HCC was developed. Imaging criteria for benign, malignant and indeterminate lesions were developed with each modality limited to 4 possible results: Benign, Indeterminate, Malignant, Not seen. Lesions <1cm were followed; lesions >2cm were worked up with 4 phase CT; Lesions 1-1.9cm were worked up with 3 contrast enhanced scans: CEUS/CT/MR. Standard imaging protocols were used. All imaging were reviewed prospectively in consensus meeting with 4 outcomes: Treat, Biopsy, Follow, Benign. Lesions fulfilling criteria for malignancy on 2/3 modality for <2cm lesions and on single modality for >2cm lesions were referred for treatment
RESULTS: 82 Lesions(median size, 1.4cm) in 55 patients underwent at least 2 imaging studies. There was agreement in 45 (63%) of 71 Lesions that had CT & CEUS. Similarly, there was agreement in 46 (66%) of 70 lesions with CEUS & MR; and 48 (68%) of 71 lesions with CT & MR. There was no statistically significant difference in rates of agreement between modality pairings. 65 lesions underwent all three modalities; there was unanimous conclusion for 32 (49%) of these lesions. In the remaining 33/65 (51%) lesions, CEUS disagreed with CT&MR results in 12 (18%), CT disagreed with CEUS&MR results in 10 (15%), and MR disagreed with CEUS/CT in 6 (9%). There was disagreement between all modalities in 5 (8%) lesions. 21/65 (32%) of lesions were deemed malignant and sent for treatment. Malignancy was deemed based on unanimous CT, CEUS and MR in 8/21 (38%) CT & CEUS only in 1 (5%), on CT&MR in 3 (14%), CEUS &MR in 7 (33%) and MR only in 2 (10%).
CONCLUSION: For small lesions found at HCC screening, unanimous consensus between 3 enhanced modalities was found in 49%. A three modality workup improved rates of diagnosis of malignant lesions.