Qualitative and quantitative contrast-enhanced ultrasonographic assessment of cerulein-induced acute pancreatitis in dogs

Candidate circulating microRNA biomarkers in dogs with chronic pancreatitis

BACKGROUND

Pancreatitis is an important cause of disease and death in dogs. Available circulating biomarkers are not sufficiently sensitive and specific for a definitive diagnosis.

HYPOTHESIS

Circulating microRNAs would be differentially expressed in dogs with chronic pancreatitis and could have potential as diagnostic biomarkers.

ANIMALS

Healthy controls (n = 19) and dogs with naturally occurring pancreatitis (n = 17).

METHODS

A retrospective case-control study. Dogs with pancreatitis were included if they satisfied diagnostic criteria for pancreatitis as adjudicated by 3 experts. MicroRNA was extracted from stored serum samples and sequenced. Reads were mapped to mature microRNA sequences in the canine, mouse, and human genomes. Differentially expressed microRNAs were identified and the potential mechanistic relevance explored using Qiagen Ingenuity Pathway Analysis (IPA).

RESULTS

Reads mapping to 196 mature microRNA sequences were detected. Eight circulating microRNAs were significantly differentially expressed in dogs with pancreatitis (≥2-fold change and false discovery rate <0.05). Four of these mapped to the canine genome (cfa-miR-221, cfa-miR-222, cfa-miR-23a, and cfa-miR-205). Three mapped to the murine genome (mmu-miR-484, mmu-miR-6240, mmu-miR-101a-3p) and 1 to the human genome (hsa-miR-1290). Expression in dogs with pancreatitis was higher for 7 microRNAs and lower for mmu-miR-101a-3p. Qiagen IPA demonstrated a number of the differently expressed microRNAs are involved in a common pancreatic inflammatory pathway.

CONCLUSIONS

The significantly differentially expressed microRNAs represent promising candidates for further validation as diagnostic biomarkers for canine pancreatitis.

Contrast-enhanced ultrasonography of the thyroid gland in healthy dogs, hypothyroid dogs and dogs with non-thyroidal illness

Diagnosis of canine hypothyroidism remains challenging, as non-thyroidal illness (NTI)-syndrome and medical treatment can influence thyroid hormone concentrations. Conventional ultrasound may give additional hints, however high interobserver variability has been described. Contrast-enhanced ultrasound (CEUS) allows detection of changes in tissue perfusion. The purpose of the present study was to assess the possible diagnostic value of CEUS regarding diagnosis of hypothyroidism. CEUS of the thyroid gland was performed in 52 healthy dogs, 16 hypothyroid dogs, and 20 NTI patients. The following perfusion parameters were calculated: Thyroid/carotid artery (TG/CA) ratios for peak enhancement (PE) and area under the curve (AUC), time to peak (TTP) and wash-in and wash-out rates (WiR, WoR) of the thyroid gland. Impact of sedation on perfusion parameters was investigated in 8 calm healthy dogs which were examined before and after sedation using midazolam and butorphanol. Significantly higher median TG/CA ratios for PE were detected for the left and right thyroid lobe in dogs with hypothyroidism (0.97/0.96) compared to healthy dogs (0.85/0.85) and dogs with NTI (0.84/0.84). AUCs were also significantly increased in hypothyroid dogs when compared to other groups. Dogs with NTI showed significantly lower WiR and WoR compared to other groups. Values for TTP were not significantly different between groups. Sedation had only impact on results of TTP which was significantly prolonged in sedated dogs. In conclusion, CEUS of the thyroid gland can provide an additional tool for diagnosis of hypothyroidism in dogs and support its differentiation from NTI. Sedation has limited impact on CEUS results.

Novel contrast agent Visphere™ is feasible for contrast-enhanced ultrasonography in dogs

Contrast-enhanced ultrasonography provides a more functional diagnostic image than conventional ultrasonography. This prospective exploratory study compared the novel contrast agent, Visphere^™ , with commercial contrast agents in five healthy Beagle dogs. Visphere^™ has the smallest diameter and highest concentration compared with Sonazoid^® and SonoVue^® . Each dog received an intravenous injection of Visphere^™ , Sonazoid^® , or SonoVue^® . Images were recorded for 300, 600, and 60 s in the heart, liver, and left kidney, respectively. The mean pixel values of the regions of interest for each organ were expressed as time intensity curves (TIC). The agents all improved the visualization of left ventricular endocardial border delineation in the heart, and had similar TICs and clinical useful durations. In contrast, Visphere^™ expressed the highest mean pixel value in the liver parenchyma at an early observation time and maintained the intensity until 600 s, like Sonazoid^® . The renal evaluation results indicated there were no statistically significant differences in time-to-peak for the renal cortex or medulla among the agents. Compared with the other two agents, SonoVue^® had the lowest peak enhancement for the renal cortex and medulla. No dogs had any adverse reactions during or after the study. All three agents provided adequate results for left ventricular endocardial border delineation, and Visphere^™ may have the same potential as Sonazoid^® to detect and characterize hepatic lesions. Visphere^™ and Sonazoid^® may offer better visualization quality to evaluate renal function. In conclusion, the novel contrast agent, Visphere^™ , is comparable with commercial agents and could be applied in different major organs in dogs.

Comparison of pancreatic and renal blood flow in a canine tachycardia-induced cardiomyopathy model

The pancreas is believed to be vulnerable to hypoperfusion. In dogs with acute pancreatitis, pancreatic ischemia due to heart failure can worsen the condition. However, changes in pancreatic blood flow associated with decreased cardiac function have not been previously studied in dogs. Therefore, we aimed to identify and compare changes in pancreatic versus renal blood flow as a result of cardiac dysfunction. Seven dogs were subjected to rapid ventricular pacing to create heart failure models. Noninvasive blood pressure measurement, ultrasonic cardiography, contrast-enhanced ultrasonography for pancreatic blood flow measurement, and para-aminohippuric acid clearance for renal blood flow measurement were performed before starting and at 2 and 4 weeks after starting the pacing. Left ventricular cardiac output and mean blood pressure decreased at 2 and 4 weeks after starting the pacing, and pancreatic blood flow decreased at 2 and 4 weeks after starting the pacing. However, renal blood flow did not change at 2 weeks but decreased 4 weeks after starting the pacing. Overall, this study demonstrated that reduced pancreatic blood flow due to cardiac dysfunction occurs, similar to renal blood flow. This suggests that decreased pancreatic blood flow is not unusual and may frequently occur in dogs with heart failure. The results of this study support the speculation that heart failure can exacerbate acute pancreatitis. Additionally, this study provides useful basic information for designing further studies to study this association.

Animal Models: Challenges and Opportunities to Determine Optimal Experimental Models of Pancreatitis and Pancreatic Cancer

At the 2018 PancreasFest meeting, experts participating in basic research met to discuss the plethora of available animal models for studying exocrine pancreatic disease. In particular, the discussion focused on the challenges currently facing the field and potential solutions. That meeting culminated in this review, which describes the advantages and limitations of both common and infrequently used models of exocrine pancreatic disease, namely, pancreatitis and exocrine pancreatic cancer. The objective is to provide a comprehensive description of the available models but also to provide investigators with guidance in the application of these models to investigate both environmental and genetic contributions to exocrine pancreatic disease. The content covers both nongenic and genetically engineered models across multiple species (large and small). Recommendations for choosing the appropriate model as well as how to conduct and present results are provided.

Evaluation of Circulating MicroRNA Biomarkers in the Acute Pancreatic Injury Dog Model

This study aimed to evaluate the usefulness of four microRNAs (miRNAs) in an acute pancreatic injury dog model. Acute pancreatitis was induced by infusion of cerulein for 2 h (7.5 μg/kg/h). The levels of well-known miRNAs, microRNA-216a (miR-216a) and microRNA-375 (miR-375), and new candidates microRNA-551b (miR-551b), and microRNA-7 (miR-7), were measured at 0, 0.5, 1, 2, 6, 12, and 24 h with serum amylase and lipase, and histopathological examination was performed. Among the four miRNAs, miR-216a and miR-375, and serum enzymes were significantly increased by cerulein treatment. The expression levels of miRNAs and serum enzymes peaked at 2–6 h with a similar pattern; however, the overall increases in miR-216a and miR-375 levels were much higher than those of the serum enzyme biomarkers. Increased levels of miR-216a and miR-375 were most highly correlated to the degree of individual histopathological injuries of the pancreas, and showed much greater dynamic response than serum enzyme biomarkers. Twenty-four-hour time-course analysis in this study revealed time-dependent changes of miRNA expression levels, from initial increase to decrease by predose level in acute pancreatitis. Our findings demonstrate that, in dogs, miR-216a and miR-375 have the potential to sensitively detect pancreatitis and reflect well the degree of pancreatic injury, whereas miR-551b and miR-7 do not.

CONTRAST-ENHANCED ULTRASONOGRAPHY OF THE PANCREAS IN HEALTHY DOGS AND IN DOGS WITH ACUTE PANCREATITIS

Pancreatitis is the most frequent disease affecting the exocrine pancreas in dogs and reliable diagnostic techniques for predicting fatal complications are lacking. Contrast-enhanced ultrasound (CEUS) improves detection of tissue perfusion as well as organ lesion vascular pattern. Objectives of this prospective case control study were to compare perfusion characteristics and enhancement patterns of the pancreas in healthy dogs and dogs with pancreatitis using CEUS. Ten healthy dogs and eight dogs with pancreatitis were selected based on physical examination, abdominal ultrasound, and blood analysis findings. A CEUS study of the pancreas was performed for each dog and two observers who were aware of clinical status used advanced ultrasound quantification software to analyze time-intensity curves. Perfusion patterns were compared between healthy and affected dogs. In dogs with acute pancreatitis, mean pixel and peak intensity of the pancreatic parenchyma was significantly higher than that of normal dogs (P = 0.05) in between 6 and 60 s (P = <0.0001-0.046). This corresponds to a 311% increase in mean pixel intensity in dogs with acute pancreatitis compared to healthy dogs. Wash-in rates were greater and had a consistently steeper slope to peak in dogs with pancreatitis as opposed to healthy dogs. All dogs with pancreatitis showed a decrease in pixel intensity 10-15 days after the initial examination (P = 0.011) and their times to peak values were prolonged compared to the initial exam. Findings from the current study supported the use of CEUS for diagnosing pancreatitis, pancreatic necrosis, and disease monitoring following therapy in dogs.

Contrast-enhanced ultrasonography of the pancreas in healthy cats

BACKGROUND

This study describes the pattern of ultrasonographic contrast enhancement of the pancreatic body and left lobe using a second-generation commercial contrast medium (Sonovue) in 10 clinically healthy cats.

RESULTS

Following contrast medium administration, microbubbles were observed within the splenic artery. This was followed by an inflow of contrast medium into the pancreatic capillary beds, providing a uniformly contrast-enhanced pancreas at peak intensity (PI). At the time of PI, a replenishment of the splenic and portal veins started and increased progressively during the wash-out phase. During the wash-out phase, the echogenicity of the pancreatic parenchyma decreased progressively. Perfusion parameters included arrival time (4.69 ± 1.26 s), time to peak from injection (7.52 ± 1.88 s), time to peak from initial rise (2.84 ± 0.88 s), peak intensity (6.58 ± 2.66 a.u.), and wash-in rate (2.11 ± 1.79 a.u./s).

CONCLUSIONS

This perfusion pattern of normal pancreatic parenchyma may be useful for characterising cats with exocrine pancreatic disorders.

Quantitative contrast-enhanced ultrasonographic assessment of naturally occurring pancreatitis in dogs

BACKGROUND

Quantitative contrast-enhanced ultrasonography (CEUS) can detect pancreatic perfusion changes in experimentally induced canine pancreatitis. However, its usefulness in detecting perfusion changes in naturally occurring pancreatitis is unclear.

HYPOTHESIS/OBJECTIVES

To determine the feasibility of using CEUS to detect pancreatic and duodenal perfusion changes in naturally occurring canine pancreatitis.

ANIMALS

Twenty-three client-owned dogs with pancreatitis, 12 healthy control dogs.

METHODS

Dogs diagnosed with pancreatitis were prospectively included. CEUS of the pancreas and duodenum were performed. Time-intensity curves were created from regions of interest in the pancreas and duodenum. Five perfusion parameters were obtained for statistical analyses: time to initial up-slope, peak time (Tp), time to wash-out (TTW), peak intensity (PI), and area under the curve (AUC).

RESULTS

For the pancreas, Tp of the pancreatitis group was prolonged when compared to controls (62 ± 11 seconds versus 39 ± 13 seconds; P < .001). TTW also was prolonged but not significantly (268 ± 69 seconds versus 228 ± 47 seconds; P = .47). PI and AUC were increased when compared to controls (95 ± 15 versus 78 ± 13 MPV; P = .009 and 14,900 ± 3,400 versus 11,000 ± 2,800 MPV*s; P = .013, respectively). For the duodenum, PI and AUC were significantly increased in the pancreatitis group when compared to controls.

CONCLUSIONS AND CLINICAL IMPORTANCE

Contrast-enhanced ultrasonography can detect pancreatic perfusion changes in naturally occurring canine pancreatitis characterized by delayed peak with prolonged hyperechoic enhancement of the pancreas on CEUS. Additionally, duodenal perfusion changes secondary to pancreatitis were observed.