Quantitative Ultrasound and the Pancreas: Demonstration of Early Detection Capability

Abstract

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.

Low fat but not soy protein isolate was an effective intervention to reduce nonalcoholic fatty liver disease progression in C57BL/6J mice: monitored by a novel quantitative ultrasound (QUS) method

“…Other factors, such as inflammation, may also affect QUS parameters of the liver. This has been observed in other tissues [46][47][48]. More data are needed to validate the use of this technique to monitor early stages of NAFLD.…”

Challenges of conducting quantitative ultrasound with a multimodal optical imaging system

“…Open-platform systems like the Verasonic's system give the user more control over the acquisition (Boni et al 2018), enabling better results, but requiring a deeper understanding and exploration of the system setup. For example, high-frequency QUS has been done on the less-flexible VEVO 2100 (Visualsonics, Toronto, Canada) system (Miller et al 2019), which allows users to simply attach high-frequency transducers and download the IQ data with minimal settings adjustments. By comparison, the Verasonics system both allows fine-tuning of parameters to achieve better results and requires custom processing scripts in order to obtain accurate power spectrums at these high-frequencies.…”

Stability of backscattering coefficient evaluation with clinical ultrasound scanner in homogeneous medium when sound field characteristics differ from reference signal

“…[11][12][13][14] There have also been also several reports that the BSC may be used to quantitatively evaluate diseases such as fatty liver, prostate cancer, lymph node metastasis, breast tumors, thyroid tumors, pancreatic fibrosis, and lymphedema dermis. [15][16][17][18][19][20][21] In addition, some studies have developed BSC methods to improve the evaluation accuracy with spatial compounding, plane wave imaging, and multiple transducer types. [22][23][24][25][26] The BSC depends on physical properties such as the scatterer diameter, the concentration, and the acoustic impedance ratio between the scatterer and surrounding media.…”