In vivo characterization of pancreatic and lymph node tissue by using EUS spectrum analysis: a validation study
Received 25 May 2009; accepted 23 August 2009. published online 18 November 2009.
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.
Current affiliations: Division of Gastroenterology (M.J.P., A.L.F., K.O., V.K.C., R.C.K.W., G.A.I., M.V.S., A.C.), University Hospitals Case Medical Center and Case Western Reserve University, Cleveland, Ohio, Division of Gastroenterology and Hepatology (F.T.F.), University of Tennessee Health Science Center, Memphis, Tennessee, Department of Biomedical Engineering (R.E.K., Y.Z., C.X.D.), The University of Michigan, Ann Arbor, Michigan, USA
Reprint requests: Ronald E. Kumon, Department of Biomedical Engineering, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, MI 48109-2099.
DISCLOSURE: All authors disclosed no financial relationships relevant to this publication.
If you would like to chat with an author of this article, you may contact Dr. Kumon at rkumon@umich.edu.
ABSTRACT