飯島 尋子¹, 森安 史典²

Hiroko IIJIMA¹, Fuminori MORIYASU²

¹兵庫医科大学超音波センター内科 肝胆膵科, ²東京医科大学消化器内科

¹Department of Internal Medicine, Hyogo College of Medicine, ²Department of Gastroenterology and Hepatology, Tokyo Medical University

キーワード : ultrasound, contrast-enhanced ultrasound, pancreatic tumor, Sonazoid, microbubble

膵腫瘤性病変では通常のBモード法に加え，造影超音波法を行うことで病変部の微細な血流動態のより正確且つ詳細な診断が期待出来る．造影超音波とは，マイクロバブルであるLevovist^®やSonazoid^®の造影剤を経静脈性に投与し膵臓では主に血流診断を行う．通常型の膵癌では，後述の3種類の染影パターンに分類される．その中でも最も多いパターンはhypovascularである．膵癌との鑑別が問題となる腫瘤形成性膵炎であるが，特にperfusion imageにおける染影態度が重要である．びまん均一なisoperfusionを呈することが多い．また典型的な膵内分泌腫瘍では,辺縁明瞭でhypervascular / hyperperfusionのhypervascularityな染影パターンを示す．

Contrast-enhanced ultrasound is performed with injections of microbubble contrast agents such as Levovist^® and Sonazoied^®. Contrast-enhanced diagnostic imaging rapidly developed in the 1980s by the introduction of intra-arterial CO₂ injection¹⁾. In September 1999, Levovist^®, a microbubble contrast agent, became available commercially in Japan. Contrast-enhanced imaging using Levovist^® is based on the fact that microbubbles are readily disrupted by exposure to ultrasound. This causes the microbubbles to produce a nonlinear ultrasound signal as they disappear. Specialized imaging modalities such as harmonic imaging are used to visualize nonlinear signal properties of microbubbles effectively. Contrast-enhanced diagnostic imaging techniques have become highly influential in the diagnosis and treatment of liver, pancreas and gallbladder tumors. This report outlines the usefulness of Levovist^® imaging and its effectiveness in the diagnostic differentiation of tumors in the liver, pancreas and gallbladder. A next-generation contrast agent, Sonazoid^®, also became available in January 2007 with insurance reimbursement. Currently, insurance reimbursement applies only when Sonazoid^® is used for diagnosis of tumorous diseases of the liver. Imaging data using Sonazoid^® obtained from pancreatic tumor cases are also described in this report.