Differential Diagnosis Of Pancreatic Tumors Using Real-time Gray Scale Contrast-enhanced Transabdominal Ultrasonography

The incident rate of pancreatic cancer had taken on a trend of increase at home and abroad. And it had become one of familiar malignant digestive tumor; it played a vital role to detect it and to identify it from malignant and benign pathological changes in the early stages.Pancreatic ultrasonography was the first choice in the pancreatic image detection and there were great clinic values to the early stage discovering of local pathological changes. But it was the simple diagnosis through conventional two-dimentional sonogram that cannot get the information of the vas of tumour and the blood supply. Therefore, it might be one of screening tools for local pathological changes because of its limitation in diagnosis.The application of color doppler ultrasonography on the diagnosis of pancreatic lesion provided valuable information for the identification and the diagnosis of pancreatic tumor at the point of blood supply and blood dynamics. But conventional color doppler ultrasound is insensitive for the slow blood flow, incapable of showing the tiny vas and subject to many factors like the angles of detection and the location of tumor etc. The use of microbubble agents can improve the detection and characterization of tumor vascularity in pancreatic tumors on color doppler ultrasonography. However, there are several limitions in Doppler studies with microbubble agents, such as blooming artifacts and insensitive to slow flow signal.As the rapid development of the modern contrast agent and the technology of contrast-enhanced ultrasonography, this revolutionary development and the historical revolution for ultrasonography makes the converting from laboratory research of ultrasonic contrast technology to clinic application quickly. If the first generation of contrast agents, such as Levovist, are used, intermittent imaging is the optimal mode. Because the contrast agent microbubbles are often destroyed under ultrasound power used for medical imaging. As the representative of the third generation modern ultrasonic contrast agent, SonoVue, under the approach of low mechanism-index, it should produce microbubble syntony without cracking; taking advantages of the nonlinearity effect produced by it and the select inception and acquiring the distribution of the bubble in the micro-circulation on the real-time, as well as showing the blood perfusion in the pancreatic tumor on the real-time distinctly, it should improve the qualitative diagnose of tumor through the characteristic of blood supply of different tumor by the showing of more blood flow and tiny vas in tumor. In addition, it may be helpful for the detecting of lesion, improving the sensitiviry of ultrasonography by the enhancing of image contrast between the pancreatic tumor and the natural pancreatic parenchyma through the using of ultrasonic contrast agent.Until now, Contrast-enhanced ultrasonography is a young field and the research of ultrasonic contrast is developing and in the stage of exploring in the clinic application. In this study, we examined patients with CPS and SonoVue to assess the usefulness of contrast-enhanced real-time harmonic gray-scale imaging in diagnosing pancreatic tumors. MATERIALS AND METHODS1. PatientsFrom March 2006 to February 2008, thirty-one patients with pancreatic masses by sonography in our department (mean age, 53.5 years, age range,23-82 years; female 18, male 13). The biggest diameter of these lesions was 6.8cm, the smallest was 0.9cm. 3 lcases were authenticated by operations or pathology puncture.2. Contrast agentThe US contrast agent SonoVue was used in all studies. A total of 2.4ml of SonoVue was injected quickly in bolus. As long as the process of contrast-enhanced US.3. InstrumentsContrast-enhanced US was performed by using Acuson Sequoia 512 (Siemens,USA) ,which was matched with Contrast Pulse Sequencing(CPS) imaging technique.4. Methods4.1 Conventional ultrasonic examinationFor all the patients, the first step is to detect the pancreas by the using of conventional two-dimensional ultrasonography, recording the location, diameter, echo phenomenon of local lesion etc; then the blood flow signals in the lesions or at the fringe of it were observed by switching on the color Doppler, and were measured by pulse Dopplerl; then the primary diagnoses were obtained before the contrast-enhanced ultrasonography.4.2 Methods of contrast ultrasonographyWhen contast enhancing, 2.4ml of SonoVue contrast agent was injected quickly through superficial vein of the elbow in 3-5 s, and then rinsed by 5ml of physiological saline solution. While beginning the real-time ultrasound contrast tuned image, the output of power was adjusted to low mechanical index status (0.05-0.20). When the rapid of injecting of contrast agent, the real-time contrast-enhanced ultrasonography state was launched simultaneously after the choice of optimal section for observation;then the dynamic injection transformation of lesion was observed continually on the real time that would be lasted for 60 second, at the end of the whole liver was detected rapidly in order to find the new lesion of metastasis.5.Statistic AnalysisAll statistics were carried out in computer with SPSS11.5 software. A probability value <0.05 was considered as statistically significant.RESULTS 1,The beginning time of enhancement:The mean beginning time of enhancement inmalignant pancreatic diseases was 14.6±2.4s;and which in benign pancreatic disesae was11.9±2.0s; the beginning time of enhancement in malignant pancreatic disease issignificantly slower than benign pancreatic disease.2,The beginning time of wash-out: The mean beginning time of wash-out in malignantpancreatic diseases was 37.2±9.6s;and which in benign pancreatic disesae was 61.9±25.7s;the beginning time of wash-out in malignant pancreatic disease is significantly faster thanbenign pancreatic disease.3,The transit time: The mean transit time of malignant pancreatic diseases was22.5±11.6s ;and which in benign pancreatic disesae was 50.0±32.4s; the transit time ofmalignant pancreatic disease is significantly shorter than benign pancreatic disease. 4,The morphology of the beginning enhancement: linear shape enhancement was dominantin the malignant pancreatic disease, branch shape enhancement was dominant in thebenign pancreatic disease.5,Enhancement form:hypo-enhancement was dominant in the malignant pancreatic disease.6,The morphology of the peak enhancement: The extent of the enhancement was differentwhen reaching peak. There were no significant difference in the morphology of the peakenhancement between the malignant and benign pancreatic tumors.CONCLUSIONThe real-time contrast-enhanced harmonic gray-scale ultrasonotraphy depicted tumor vascularity in pancreatic tumors sensitively and accurately. It depicted tumor vascularity and tumor perfusion flow in a real-time fashion on continuous imaging. It should improve the qualitative diagnosis for the local pancreatic lesion, and should be helpful for the identification of the malignant tumor and benign tumor; So it is very importand in clinical application.