Acoustic radiation force impulse elastography for noninvasive assessment of chronic pancreatitis.

BACKGROUND: Endoscopic ultrasonography or real-time elastography has been applied for the diagnosis of chronic pancreatitis. Acoustic radiation force impulse (ARFI) imaging is another tissue strain imaging technology, and recent technological advances have enabled quantification of the stiffness of some tissues by measuring the shear wave velocity (SWV) during routine B-mode ultrasonography. METHODS: ARFI elastography was performed in 52 healthy volunteers and 46 patients with chronic pancreatitis. SWV was measured in the head, body, and tail of the pancreas. The diagnostic performance was assessed using receiver-operating characteristic (ROC) curves. RESULTS: SWV in patients with chronic pancreatitis was significantly higher than that in healthy volunteers in each part of the pancreas, although the measurement was difficult in the tail of the pancreas. The area under the ROC curve was 0.78 in the body of the pancreas, with an optimal cut-off value of 1.40 m/s, and the sensitivity, specificity, positive predictive value, and negative predictive value were 75, 72, 69, and 78%, respectively. In the patients with chronic pancreatitis, alcoholic etiology and decreased body mass index (BMI) were associated with high SWV. CONCLUSIONS: ARFI elastography of the pancreas showed high elasticity in chronic pancreatitis compared to findings in the normal pancreas. This modality is feasible to use for the diagnosis of chronic pancreatitis.

Intraductal US in the assessment of tumor involvement to the orifice of the cystic duct by malignant biliary obstruction.

BACKGROUND: Tumor involvement to the orifice of the cystic duct (OCD) is a risk factor for cholecystitis after metallic stent (MS) placement. OBJECTIVE: ERCP and intraductal US (IDUS) were used to assess tumor involvement to the OCD. DESIGN: A prospective consecutive study. SETTING: The University of Tokyo Hospital, Japan. PATIENTS AND INTERVENTIONS: Between January 2003 and May 2007, 34 patients with resectable malignant biliary obstruction underwent an ERCP and an IDUS before preoperative biliary drainage. MAIN OUTCOME MEASUREMENTS: ERCP and IDUS findings were confirmed via a histopathologic analysis of surgical specimens. RESULTS: An ERCP showed that the cystic duct was opacified in 22 of 34 patients (64.7%). Eight patients were diagnosed with OCD tumor involvement. In the remaining 12 patients, tumor involvement was impossible to evaluate via an ERCP. An IDUS identified tumor involvement to the OCD in all 34 patients. Tumor involvement to the OCD was diagnosed in 12 patients, including 4 patients with previously negative results during an ERCP. Tumor involvement was confirmed by histopathology of surgical specimens. The sensitivity and specificity of detection were 66.7% (8/12) and 63.6% (14/22), respectively, via ERCP, and 100% (12/12) and 100% (22/22), respectively, via IDUS. LIMITATION: The small sample size. CONCLUSIONS: IDUS, in addition to ERCP, provides an accurate evaluation of tumor involvement to the OCD in patients with malignant biliary obstruction.