TY - JOUR
T1 - Quantitative Ultrasound and the Pancreas
T2 - Demonstration of Early Detection Capability
AU - Miller, Rita J.
AU - Han, Aiguo
AU - Erdman, John W.
AU - Wallig, Matthew A.
AU - O'Brien, William D.
N1 - Funding Information:
Immediately after euthanasia, the pancreas was removed en masse and weighed (Table). The surgery incision was enlarged using iris scissors and forceps. To avoid manipulation and subsequent damage of the pancreatic tissue, it was removed by holding the stomach and duodenum in one hand, stretching out the pancreatic tissue, and cutting the tissue away with the other. In addition, forceps were used to elevate the spleen to remove the attached pancreatic tissue. The entire pancreas was then gently lifted from below to place it on the dissecting table. Care was taken whenever handling the pancreatic tissue to preserve the integrity of the tissue for histologic analysis. A piece of pancreatic tissue no thicker than 2 mm was removed from the splenic region for ex vivo QUS scanning. It was placed in degassed 0.9% NaCl for transport to the scanning station. Sections from the splenic and gastric regions were trimmed and placed in tissue processing cassettes on a foam biopsy pad and fixed in 10% neutral buffered formalin for subsequent histopathologic evaluation (see below). The ex vivo pancreatic tissue was ultrasonically scanned with a single-element 40-MHz focused transducer (25–55 MHz; f-number, 3; National Institutes of Health High-Frequency Transducer Resource Center, University of Southern California, Los Angeles, CA). The transducer was connected to a UTEX UT340 pulser/receiver (UTEX Scientific Instruments Inc, Mississauga, Ontario, CA) and moved via a computer-controlled positioning system (Daedal Parker Hannifin Corp, Irwin, PA). The pancreatic tissue was placed on Plexiglas within a tank filled with room temperature degassed 0.9% NaCl. The ex vivo AC and BSC were obtained by using a through-transmission technique in the pulse-echo mode and a planar reference method, respectively. The comprehensive implementation details are documented in work by Han et al and briefly summarized as follows. The ex vivo AC was computed by comparing the echo signals from the Plexiglas with and without the pancreas tissue placed in the acoustic path.
Publisher Copyright:
© 2018 by the American Institute of Ultrasound in Medicine
PY - 2019/8
Y1 - 2019/8
N2 - Objectives: To show that quantitative ultrasound biomarkers attenuation (AC) and backscatter (BSC) coefficients are effective tools to detect early changes in acute pancreatitis, using a cerulein-induced pancreatitis rat model. Methods: Sprague-Dawley rats (n = 68) were divided into 8 groups: uninjected cage controls, saline-injected controls, and cerulein-injected rats euthanized at 2, 4, 15, 24, 48, and 60 hours after injection. Pancreatic AC and BSC (25–55 MHz) were estimated in vivo (Vevo 2100, VisualSonics, Toronto, CA) and ex vivo (40-MHz transducer). The pancreas of each rat was evaluated histopathologically. Results: Changes in both in vivo and ex vivo AC and BSC relative to controls reflected temporal histomorphologic changes. Overall, there were decreased AC and BSC at early time points and then rebound toward control values over time. Maximal in vivo AC and BSC decreases occurred at 2 hours after cerulein injection. Attenuation coefficient changes corresponded well with early pancreatic edema and acinar cell vacuolation, with rebound as edema decreased, autophagy/cellular death occurred, and histiocytic infiltrates and fibrosis manifested. Backscatter coefficient decreased early but rebounded as autophagy and apoptosis increased, only to fall as acinar atrophy peaked, and fibrosis and histiocytic infiltration increased. Conclusions: Cerulein-induced pancreatitis is an excellent model for studying ultrasonic AC and BSC biomarkers during the early stages of acute pancreatitits, reflecting microscopic structural changes. Edema followed by cell shrinkage and apoptosis, then histiocytic infiltration and fibrosis, has certain similarities with the morphologies of some forms of pancreatic carcinoma. This suggests that quantitative ultrasound may be very useful for early detection of disease onset or response to therapy for not only acute pancreatitis but also pancreatic cancer.
AB - Objectives: To show that quantitative ultrasound biomarkers attenuation (AC) and backscatter (BSC) coefficients are effective tools to detect early changes in acute pancreatitis, using a cerulein-induced pancreatitis rat model. Methods: Sprague-Dawley rats (n = 68) were divided into 8 groups: uninjected cage controls, saline-injected controls, and cerulein-injected rats euthanized at 2, 4, 15, 24, 48, and 60 hours after injection. Pancreatic AC and BSC (25–55 MHz) were estimated in vivo (Vevo 2100, VisualSonics, Toronto, CA) and ex vivo (40-MHz transducer). The pancreas of each rat was evaluated histopathologically. Results: Changes in both in vivo and ex vivo AC and BSC relative to controls reflected temporal histomorphologic changes. Overall, there were decreased AC and BSC at early time points and then rebound toward control values over time. Maximal in vivo AC and BSC decreases occurred at 2 hours after cerulein injection. Attenuation coefficient changes corresponded well with early pancreatic edema and acinar cell vacuolation, with rebound as edema decreased, autophagy/cellular death occurred, and histiocytic infiltrates and fibrosis manifested. Backscatter coefficient decreased early but rebounded as autophagy and apoptosis increased, only to fall as acinar atrophy peaked, and fibrosis and histiocytic infiltration increased. Conclusions: Cerulein-induced pancreatitis is an excellent model for studying ultrasonic AC and BSC biomarkers during the early stages of acute pancreatitits, reflecting microscopic structural changes. Edema followed by cell shrinkage and apoptosis, then histiocytic infiltration and fibrosis, has certain similarities with the morphologies of some forms of pancreatic carcinoma. This suggests that quantitative ultrasound may be very useful for early detection of disease onset or response to therapy for not only acute pancreatitis but also pancreatic cancer.
KW - attenuation coefficient (AC)
KW - backscatter coefficient (BSC)
KW - cerulein
KW - early detection
KW - pancreatitis
KW - quantitative ultrasound
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U2 - 10.1002/jum.14901
DO - 10.1002/jum.14901
M3 - Article
C2 - 30575064
AN - SCOPUS:85070056016
SN - 0278-4297
VL - 38
SP - 2093
EP - 2102
JO - Journal of Ultrasound in Medicine
JF - Journal of Ultrasound in Medicine
IS - 8
ER -