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Background: Spectral analysis of the radiofrequency (RF) signals that underlie grayscale EUS images has been used to provide quantitative, objective information about tissue histology., Objective: Our purpose was to validate RF spectral analysis as a method to distinguish between chronic pancreatitis (CP) and pancreatic cancer (PC)., Design and Setting: A prospective study of eligible patients was conducted to analyze the RF data obtained by using electronic array echoendoscopes., Patients: Pancreatic images were obtained by using electronic array echoendoscopes from 41 patients in a prospective study, including 15 patients with PC, 15 with CP, and 11 with a normal pancreas., Main Outcome Measurements: Midband fit, slope, intercept, correlation coefficient, and root mean square deviation from a linear regression of the calibrated power spectra were determined and compared among the groups., Results: Statistical analysis showed that significant differences were observable between groups for mean midband fit, intercept, and root mean square deviation (t test, P < .05). Discriminant analysis of these parameters was then performed to classify the data. For CP (n = 15) versus PC (n = 15), the same parameters provided 83% accuracy and an area under the curve of 0.83., Limitations: Moderate sample size and spatial averaging inherent in the technique., Conclusions: This study shows that mean spectral parameters of the backscattered signals obtained by using electronic array echoendoscopes can provide a noninvasive method to quantitatively discriminate between CP and PC., (Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.)

Background: Primary upper endoscopy (EGD) and transabdominal US (TUS) are often performed in patients with upper abdominal pain., Objective: Primary: Determine whether the combination of EGD and EUS was equivalent to EGD plus TUS in the diagnostic evaluation of upper abdominal pain. Secondary: Compare EUS versus TUS in detecting abdominal lesions, and compare EGD by using an oblique-viewing echoendoscope versus the standard, forward-viewing endoscope in detecting mucosal lesions., Design: Prospective, paired design., Setting: Six academic endoscopy centers., Patients: This study involved patients with upper abdominal pain referred for endoscopy., Intervention: All patients had EGD, EUS, and TUS. The EGD was done using both an oblique-viewing echoendoscope and the standard, forward-viewing endoscope (randomized order) by two separate endoscopists in a blinded fashion, followed by EUS. TUS was performed within 4 weeks of EGD/EUS, also in a blinded fashion., Follow-Up: telephone interviews and chart reviews., Main Outcome Measurements: Diagnose possible etiology of upper abdominal pain and detect clinically significant lesions., Results: A diagnosis of the etiology of upper abdominal pain was made in 66 of 172 patients (38%). The diagnostic rate was 42 of 66 patients (64%) for EGD plus EUS versus 41 of 66 patients (62%) for EGD plus TUS, which was statistically equivalent (McNemar test; P = .27). One hundred ninety-eight lesions were diagnosed with either EUS or TUS. EUS was superior to TUS for visualizing the pancreas (P < .0001) and for diagnosing chronic pancreatitis (P = .03). Two biliary stones were detected only by EUS. Two hundred fifty-one mucosal lesions were similarly diagnosed with EGD with either the standard, forward-viewing endoscope or the oblique-viewing echoendoscope (kappa = 0.48 [95% CI, .43-.54]). EGD with the standard, forward-viewing endoscope was preferred for biopsies., Limitations: No cost analysis., Conclusion: The combination of EGD with EUS is equivalent to EGD plus TUS for diagnosing a potential etiology of upper abdominal pain. EUS is superior to TUS for detecting chronic pancreatitis. EGD combined with EUS should be considered in the first-line diagnostic evaluation of patients with upper abdominal pain., (Copyright © 2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.)

Background: Real-time visualization of submucosal arterial flow at the base of an ulcer might improve endoscopic hemostasis by permitting more accurate assessment of the artery, precise targeting of therapy, and confirmation of vessel ablation., Objective: To evaluate the utility of a novel, forward-viewing echoendoscope in identifying bleeding submucosal arteries, guiding hemostatic therapy, and confirming cessation of flow through treated vessels., Design: In 7 pigs, a previously described porcine model for peptic ulcer hemorrhage was created by isolating the gastroepiploic and/or short gastric artery and tunneling it into the subserosal space at laparotomy., Setting: Animal research facility., Intervention: The prototype endoscope was used to image submucosal arterial flow. EUS guidance was then used to deliver endoscopic hemostatic therapy and assess treatment adequacy., Main Outcome Measurements: Identification of the target submucosal artery and successful delivery of EUS-guided endoscopic therapy, evidenced by cessation of Doppler flow through the target vessel., Results: Tunneled arteries were visualized endosonographically in all 7 cases. EUS-guided submucosal injection of epinephrine was successful in 2 of 2 cases. EUS-guided delivery of thermal hemostatic therapy was successful in 2 of 4 cases. Absence of flow through treated vessels was confirmed in cases in which EUS-guided therapy was successfully delivered., Limitations: Acute animal model., Conclusion: Proof of principle experiments in a porcine peptic ulcer hemorrhage model suggest that real-time sonographic imaging of submucosal arteries is feasible with a forward-viewing echoendoscope, and guided hemostatic therapy can be delivered., (Copyright 2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.)

Background: Quantitative spectral analysis of the radiofrequency (RF) signals that underlie grayscale EUS images can be used to provide additional, objective information about tissue state., Objective: Our purpose was to validate RF spectral analysis as a method to distinguish between (1) benign and malignant lymph nodes and (2) normal pancreas, chronic pancreatitis, and pancreatic cancer., Design and Setting: A prospective validation study of eligible patients was conducted to compare with pilot study RF data., Patients: Forty-three patients underwent EUS of the esophagus, stomach, pancreas, and surrounding intra-abdominal and mediastinal lymph nodes (19 from a previous pilot study and 24 additional patients)., Main Outcome Measurements: Midband fit, slope, intercept, and correlation coefficient from a linear regression of the calibrated RF power spectra were determined., Results: Discriminant analysis of mean pilot-study parameters was then performed to classify validation-study parameters. For benign versus malignant lymph nodes, midband fit and intercept (both with t test P < .058) provided classification with 67% accuracy and area under the receiver operating curve (AUC) of 0.86. For diseased versus normal pancreas, midband fit and correlation coefficient (both with analysis of variance P < .001) provided 93% accuracy and an AUC of 0.98. For pancreatic cancer versus chronic pancreatitis, the same parameters provided 77% accuracy and an AUC of 0.89. Results improved further when classification was performed with all data., Limitations: Moderate sample size and spatial averaging inherent to the technique., Conclusions: This study confirms that mean spectral parameters provide a noninvasive method to quantitatively discriminate benign and malignant lymph nodes as well as normal and diseased pancreas., (2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.)

This study assessed the ability of spectral analysis of endoscopic ultrasound (EUS) RF signals acquired in humans in vivo to distinguish between (1) benign and malignant intraabdominal and mediastinal lymph nodes and (2) pancreatic cancer, chronic pancreatitis, and normal pancreas. Mean midband fit, slope, intercept, and correlation coefficient from a linear regression of the calibrated RF power spectra were computed over regions of interest defined by the endoscopist. Linear discriminant analysis was then performed to develop a classification of the resulting spectral parameters. For lymph nodes, classification based on the midband fit and intercept provided 67% sensitivity, 82% specificity, and 73% accuracy for malignant vs. benign nodes. For pancreas, classification based on midband fit and correlation coefficient provided 95% sensitivity, 93% specificity, and 93% accuracy for diseased vs. normal pancreas and 85% sensitivity, 71% specificity, and 85% accuracy for pancreatic cancer vs. chronic pancreatitis. These promising results suggest that mean spectral parameters can provide a non-invasive method to quantitatively characterize pancreatic cancer and lymph malignancy in vivo.

Background: EUS is limited by variability in the examiner's subjective interpretation of B-scan images to differentiate among normal, inflammatory, and malignant tissue. By using information otherwise discarded by conventional EUS systems, quantitative spectral analysis of the raw radiofrequency (RF) signals underlying EUS images enables tissue to be characterized more objectively., Objective: Our purpose was to determine the feasibility of using spectral analysis of EUS data for characterization of pancreatic tissue and lymph nodes., Design and Setting: A pilot study of eligible patients was conducted to analyze the RF data obtained during EUS by using spectral parameters., Patients: Twenty-one subjects who underwent EUS of the esophagus, stomach, pancreas, and surrounding intra-abdominal and mediastinal lymph nodes., Main Outcome Measurements: Linear regression parameters of calibrated power spectra of the RF signals were tested to differentiate normal pancreas from chronic pancreatitis and from pancreatic cancer as well as benign from malignant-appearing lymph nodes., Results: The mean intercept, slope, and midband fit of the spectra differed significantly among normal pancreas, adenocarcinoma, and chronic pancreatitis when all were compared with each other (P < .01). On direct comparison, mean midband fit for adenocarcinoma differed significantly from that for chronic pancreatitis (P < .05). For lymph nodes, mean midband fit and intercept differed significantly between benign- and malignant-appearing lymph nodes (P < .01 and P < .05, respectively)., Limitations: Small sample population and spatial averaging inherent to this technique., Conclusions: Mean spectral parameters in EUS imaging can provide a noninvasive method to discriminate normal from diseased pancreas and lymph nodes.

Background: EUS often is performed because of a clinical suspicion of pancreatic cancer when the results of other noninvasive diagnostic tests are indeterminate. The aim of this study was to determine the true negative predictive value of a normal EUS in a cohort of patients with an indeterminate suspicion of pancreatic cancer by obtaining long-term follow-up information., Methods: Patients referred for EUS of the pancreas for the following indications were identified: elevated carbohydrate-associated antigen (CA 19-9) without other definitive evidence of pancreatic cancer, subtle abnormalities on CT of the pancreas, and unexplained abdominal pain and/or weight loss. Endoscopy procedure reports, as well as inpatient and outpatient records were obtained. In addition, referring physicians, as well as patients, were contacted to acquire adequate follow-up information., Results: A total of 80 patients were included in the study. Follow-up of at least 6 months was obtained for 76 (95%) patients (mean follow-up 23.9 months). No patient with a normal EUS of the pancreas developed pancreatic cancer or required pancreatic surgery during the follow-up period. One patient in whom a diagnosis of chronic pancreatitis was made by EUS subsequently was found to have pancreatic cancer at surgery., Conclusions: A normal EUS of the pancreas in the setting of subtle radiologic findings, serologic abnormalities, and/or nonspecific symptoms definitively rules out the presence of pancreatic cancer.

Background: Intraductal US can improve the diagnostic accuracy of cholangiography performed under C-arm fluoroscopy in patients with suspected choledocholithiasis. This study aimed to determine the clinical utility of intraductal US for patient management., Methods: Patients with suspected choledocholithiasis undergoing ERCP with a C-arm fluoroscope at two tertiary academic medical centers were enrolled. After initial cholangiography, findings and decisions concerning the need for further interventions were recorded. Intraductal US (20 MHz) was then selectively performed in patients with equivocal cholangiography or those without cholangiographic evidence of bile duct stones. Intraductal US was also performed after endoscopic sphincterotomy and stone extraction to confirm bile duct clearance., Results: Fifty-two patients (28 men, 24 women) were enrolled and intraductal US was selectively performed in 35 (64%). Of the 21 patients with normal cholangiography, 8 (38%) had stones or sludge by intraductal US. Endoscopic sphincterotomy was performed as a direct result of intraductal US in these 8 and the findings were confirmed in 7. In the 14 patients in whom cholangiography demonstrated small (<5 mm) or round filling defects, intraductal US concurred in 9 and found air bubble/no stone in 5. Sphincterotomy was avoided in these 5 patients. Overall, intraductal US led to a change in clinical management in 13 of 35 patients (37%) in whom it was performed., Conclusions: Selective use of intraductal US affects the clinical management of a large proportion of patients who undergo C-arm fluoroscopy-guided ERCP for suspected bile duct stones.