title: EUS elastography combined with the strain ratio of tissue elasticity for diagnosis of solid pancreatic masses.
abstract: BACKGROUND
  Recently, the usefulness of endoscopic ultrasound (EUS) elastography has been reported for the diagnosis of pancreatic lesions. In the present study, we retrospectively assessed EUS elastography as a diagnostic tool by evaluating tissue elasticity distribution and elasticity semiquantification, using the strain ratio (SR) of tissue elasticity, in patients with pancreatic masses.
  
  
  METHODS
  One hundred and nine patients who underwent EUS elastography between September 2006 and May 2009 were retrospectively evaluated. The final diagnosis was chronic pancreatitis (CP) in 20 patients [6 with non-mass-forming pancreatitis, 7 with mass-forming pancreatitis (MFP), and 7 with autoimmune pancreatitis (AIP)], pancreatic cancer (PC) in 72, pancreatic neuroendocrine tumor (PNET) in 9, and normal pancreas in 8. The tissue elasticity distribution calculation was performed in real time, and the results were represented in color in fundamental B-mode imaging. In addition, we performed quantification using the SR (non-mass area/mass area).
  
  
  RESULTS
  Elastography for all PC patients showed intense blue coloration, indicating malignant lesions. In contrast, MFP presented with a mixed coloration pattern of green, yellow, and low-intensity blue. Normal controls showed an even distribution of green to red. The mean SR was 23.66 ± 12.65 for MFP and 39.08 ± 20.54 for PC (P < 0.05).
  
  
  CONCLUSIONS
  Endoscopic ultrasound elastography is a promising diagnostic tool for defining the tissue characteristics of pancreatic masses. In addition, semiquantitative analysis of elasticity using the SR may allow the differentiation of MFP from PC.
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
authors.forename: Fumihide
authors.initials: F
authors.lastname: Itokawa
authors.forename: Takao
authors.initials: T
authors.lastname: Itoi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sofuni
authors.forename: Toshio
authors.initials: T
authors.lastname: Kurihara
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ishii
authors.forename: Shujiro
authors.initials: S
authors.lastname: Tsuji
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Ikeuchi
authors.forename: Junko
authors.initials: J
authors.lastname: Umeda
authors.forename: Reina
authors.initials: R
authors.lastname: Tanaka
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Fuminori
authors.initials: F
authors.lastname: Moriyasu
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kasuya
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Nagao
authors.forename: Terumi
authors.initials: T
authors.lastname: Kamisawa
authors.forename: Akihiko
authors.initials: A
authors.lastname: Tsuchida
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004548:Elasticity; D054459:Elasticity Imaging Techniques / Q000379:methods*; D019160:Endosonography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000175:diagnosis* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000473:pathology; D010195:Pancreatitis / Q000175:diagnosis / Q000473:pathology; D012189:Retrospective Studies