Qualitative and Quantitative Contrast-enhanced Endoscopic Ultrasound Improves Evaluation of Focal Pancreatic Lesions

Abstract

Endoscopic ultrasound (EUS) is a sensitive method to evaluate the pancreas but its diagnostic capability for several diseases is limited. We compared the diagnostic yield of unenhanced EUS with that of contrast-enhanced EUS for focal pancreas lesions and identified and tested quantitative parameters of contrast enhancement. We performed a prospective tandem-controlled trial in which 101 patients with focal pancreas lesions (48 with masses, 28 with cysts, and 25 with pancreatitis) underwent conventional EUS followed by contrast EUS using intravenous perflutren microspheres. The diagnosis at each stage was scored and compared with a standard (findings from surgical pathology analysis, cytologic, and/or 6-month clinical follow-up evaluations). Quantitative parameters were generated by time-intensity curve analysis. Solid lesions were divided into derivation and testing cohorts for a crossover validation analysis of the quantitative parameters. The primary outcome was diagnostic yield of unenhanced vs contrast EUS in analysis of focal pancreas lesions. Contrast increased the diagnostic yield of EUS from 64% (65/101 lesions accurately assessed) to 91% (92/101 lesions accurately assessed); the odds ratio [OR] was 7.8 (95% CI, 2.7-30.2) for accurate analysis of lesions by contrast-enhanced EUS relative to unenhanced EUS. The contrast increased accuracy of analysis of pancreas masses (OR, 6.0; 95% CI, 1.8-31.8), improving assessment of neuroendocrine and other (non-carcinoma) tumors. Contrast increased the diagnostic yield for pancreas cysts to 96% (27/28) compared with 71.4% (20/28) for unenhanced EUS (P = .02), due to improved differentiation of mural nodules vs debris. Time-intensity curve analysis revealed distinct patterns of relative peak enhancement (rPE) and in-slope (rIS) for different lesions following contrast injection: for adenocarcinomas, values were low rPE and low rIS; for neuroendocrine masses, values were high rPE and normal IS; and for chronic pancreatitis foci, values were normal rPE and low rIS. In the validation cohort, these parameters correctly characterized 91% of lesions and improved yield relative to unenhanced EUS (OR, 10; 95% CI, 1.4-34.0). Contrast-enhanced EUS improves the accuracy of analysis of focal pancreas lesions, compared with unenhanced EUS. Integration of practical quantitative parameters, specifically relative peak enhancement and in-slope, might increase the diagnostic accuracy of contrast EUS. ClinicalTrials.gov no:02863770.