The Application Of Contrast Enhanced Ultrasound In The Diagnosis Of Solid Focal Lesions In Pancreas

Purpose:1. Investigate the value of software-aided quantitative analysis of transabdominalcontrast enhanced ultrasound (CEUS) for differential diagnosis of pancreatic ductaladenocarcinoma (PDAC) and tumor-like chronic pancreatitis (CP).2. To evaluate theclinical practical value of percutaneous CEUS guided biopsy of focal pancreatic lesions(FPLs) that are not confidently localized on B-mode ultrasound (US).Materials and methods:1. Seventy-one patients for whom it was difficult to differentiate between aninflammatory focal lesion of the pancreas and a pancreatic carcinoma underwent CEUS.Two regions of interest (ROI), one within the lesion and another within the pancreaticparenchyma, were selected in each patient to obtain time-intensity curve (TIC).Differences of the lesion and the pancreatic parenchyma between PDAC and CP wereevaluated. Receiver operating characteristic curve (ROC) was used to evaluate thecutoff value and the diagnostic accuracy of parameters with statistical significance.2.Totally54patients with pancreatic masses underwent percurtanneous biopsy guided byCEUS. All of the biopsy targets could not be confidently localized with B-mode US.When the aquaired tissues could give definite diagnosis, the sample was defined assatisifactory. Follow-up lasted at least6months. The results of the pathologicaldiagnosis or the follow-up imaging studies were taken as the final diagnosis.Results:1. Clinical or pathological diagnosis confirmed the presence of PDAC in57patients andtumor-like pancreatitis due to CP in14patients. The average depth from the surface ofROI was (5.28±0.99) cm (1) The sensitivity, specificity, accuracy and positivepredictive value (PPV) of CEUS itself was77.2%,57.1%,73.2%and88.0%,respectively (2) There were significant differences in relative rise time (RT) and relative time to peak (TTP) between PDAC and tumor-like CP (P<0.05).(3)△RT and△TTP ofPDAC were both longer than those of tumor-like CP,(2.8s [95%CI:2.4–4.8] vs1.4s[95%CI:1.0–2.6], P=0.025) and (3.4s [95%CI:3.0–6.2] vs1.6s [95%CI:1.1–3.2],P=0.022).(4) Taking△RT≥1.48s as diagnostic indicator for differentiating PDAC fromtumor-like CP, the accuracy, sensitivity, specificity, PPV and NPV was74.6%,78.9%,57.1%,66.2%and66.3%, respectively. Taking△TTP≥1.65s as diagnostic indicator, theaccuracy, sensitivity, specificity, PPV and NPV was77.5%,80.7%,64.3%,71.5%and71.6%, respectively.(5) Viewing△RT≥1.48s or△TTP≥1.65s as diagnostic indicator,the sensitivity, specificity, accuracy and PPV were improved to82.5%、78.6%、81.7%and94.0%, respectively. The results was higher than CEUS (X2=5.09，P=0.02)；2. Of the53biopsy lesions in51patients,11(11/53,20.75%) were benign and42(42/53,79.25%) were malignant. The satisfactory rate of percutaneous biopsy was96.08%(49/51). The accuracy of biopsy with satisfactory sampling was95.92%(47/49).Thesensitivity and specificity in diagnosing malignancy was95.00%(38/40) and100%respectively. No major complications occurred in our study except one case (1/51,1.96%) of biliary peritonitis. Conclusions:1.(1) In contrast to CEUS itself, quantitative analysis of CEUS supplies a moresubjective visual assessment with objective and effective criteria to facilitate thedifferential diagnosis of PDAC and tumor-like CP.(2) Relative time-dependedparameters like△RT and△TTP has significant differences in differentiating PDACand tumor-like CP. A combination of them will improve the diagnositic value of PDAC.(3) Using late-in perfusion mode as a diagnosis indicator is more meaningful andintuitive.(4) It is easily possible for average sonographer to add strong evidence to thevisual impression of CEUS examination as the software automatically calculates theparameters in ROI.2. For pancreatic space occupying lesions which can’t beconfidently localized on B-mode US, percutaneous biopsy under the control of CEUScan improve the accuracy of puncture and reduce the incidence of complication.