Sonographic pancreas echogenicity in cystic fibrosis compared to exocrine pancreatic function and pancreas fat content at Dixon-MRI.

OBJECTIVE: Fatty infiltration of the pancreas is a dominating feature in cystic fibrosis (CF). We evaluate the association between pancreatic fat content assessed by Dixon magnetic resonance imaging (MRI), pancreatic echogenicity at ultrasonography (US) and exocrine function in CF patients and healthy controls (HC). MATERIAL AND METHODS: Transabdominal US, pancreatic Dixon-MRI and diffusion-weighted imaging (DWI) were performed in 21 CF patients and 15 HCs. Exocrine function was assessed by endoscopic secretin test and fecal elastase. RESULTS: CF patients were grouped according to exocrine pancreatic function as subjects with normal (CFS: n = 11) or reduced (CFI: n = 10) function. Among CFI 90% (9/10) had visual hyperechogenicity. CFI also had increased echo-level values (p<0.05 vs others). All CFI (10/10) had markedly increased pancreatic fat content estimated by MRI compared to sufficient groups, p<0.001). Among CFS patients and HC, 27% (3/11) and 33% (5/15), respectively, had hyperechoic pancreas. However, all these had low pancreatic fat-content at MRI compared to CFI. In CFI, pancreatic fat content was correlated to ADC (r = -0.93, p<0.001). CONCLUSION: Pancreas insufficient CF patients exhibit severe pancreatic fatty-infiltration at MRI and hyperechoic pancreas at US. Pancreas hyperechogenicity in pancreatic sufficient subjects does not co-exist with fatty infiltration at MRI. MRI evaluates pancreatic fatty infiltration more accurately than US and fat infiltration estimated by MRI outperforms sonographic hyper-echogenicity as a marker for exocrine pancreatic failure in CF.

Contrast-enhanced ultrasonography of the pancreas shows impaired perfusion in pancreas insufficient cystic fibrosis patients.

BACKGROUND: Perfusion assessment of the pancreas is challenging and poorly evaluated. Pancreatic affection is a prevalent feature of cystic fibrosis (CF). Little is known about pancreatic perfusion in CF. We aimed to assess pancreatic perfusion by contrast-enhanced ultrasound (CEUS) analysed in the bolus-and-burst model and software. METHODS: We performed contrast enhanced ultrasound of the pancreas in 25 CF patients and 20 healthy controls. Perfusion data was analysed using a dedicated perfusion model providing the mean capillary transit-time (MTT), blood flow (BF) and blood-volume (BV). CF patients were divided according to exocrine function. RESULTS: The pancreas insufficient CF patients had longer MTT (p ≤ 0.002), lower BF (p < 0.001) and lower BV (p < 0.05) compared to the healthy controls and sufficient CF patients. Interrater analysis showed substantial agreement for the analysis of mean transit time. CONCLUSION: The bolus-and-burst method used on pancreatic CEUS-examinations demonstrates reduced perfusion in CF patients with pancreas affection. The perfusion model and software requires further optimization and standardization to be clinical applicable for the assessment of pancreatic perfusion.

Secretin-stimulated MRI assessment of exocrine pancreatic function in patients with cystic fibrosis and healthy controls.

PURPOSE: Secretin-stimulated magnetic resonance imaging (s-MRI) and pancreatic diffusion weighted imaging (DWI) are novel non-invasive imaging techniques for assessment of exocrine pancreatic insufficiency (EPI). The aim was to validate s-MRI assessed pancreatic secreted volume using novel semi-automatic quantification software, and to assess the ability of s-MRI with DWI to diagnose EPI in patients with cystic fibrosis (CF). METHODS: s-MRI and DWI was performed in 19 patients with CF (median age 21 years; range 16-56; eight men) and in 10 healthy controls (HC) (median age 46 years; range 20-65; four men). Sequential coronal T2-weighted images covering the duodenum and small bowel and axial DWI were acquired before and 1, 5, 9, and 13 min after secretin stimulation. A short endoscopic secretin test was used as reference method for EPI. RESULTS: CF patients with EPI had lower apparent diffusion coefficient before secretin in the pancreatic head (P < 0.001) and lower secreted bowel fluid volumes (P = 0.035) compared to HC and CF patients without EPI. ROC curve analyses identified that secreted fluid volume after 13 min yielded the highest diagnostic accuracy for diagnosing EPI (AUC 0.93; 95% CI [0.80-1.00]). CONCLUSION: Pancreatic s-MRI is useful for the assessment of exocrine pancreatic function with high diagnostic accuracy for the diagnosis of EPI in CF.

Diagnostic Accuracy of a Short Endoscopic Secretin Test in Patients With Cystic Fibrosis.

OBJECTIVE: Short endoscopic secretin tests for exocrine pancreatic function are not properly evaluated in cystic fibrosis (CF). METHODS: Patients with CF and healthy controls (HCs) underwent endoscopic collection of duodenal juice between 30 and 45 minutes after secretin stimulation. Duodenal juice was analyzed for HCO3 concentration and pancreatic enzyme activities. Stool was analyzed for fecal elastase. RESULTS: Thirty-one patients with CF and 25 HCs were tested. Patients were classified as exocrine pancreatic sufficient (n = 13) or insufficient (n = 18). Both bicarbonate concentrations and enzyme activities in duodenal juice differentiated patients with CFI from patients with CFS and HC (P < 0.001). The population displays strong correlation between severe CF genotype in both alleles and pancreatic insufficient phenotype (P < 0.001). CONCLUSIONS: Pancreatic exocrine insufficient CF patients could be differentiated from exocrine sufficient patients and HCs using short endoscopic secretin test.