In computer-aided diagnosis (CAD) systems for prostate cancer, dynamic contrast enhanced (DCE) magnetic resonance imaging is useful for distinguishing cancerous and benign tissue. The Tofts physiological model is a commonly used representation of the DCE image data, but the parameters require extensive computation. Hence, we developed an alternative representation based on the Hilbert transform of the DCE images. The time maximum of the Hilbert transform, a binary metric of early enhancement, and a pre-DCE value was assigned to each voxel and appended to a standard feature set derived from T2-weighted images and apparent diffusion coefficient maps. A cohort of 40 patients was used for training the classifier, and 20 patients were used for testing. The AUC was calculated by pooling the voxel-wise prediction values and comparing with the ground truth. The resulting AUC of 0.92 (95% CI [0.87 0.97]) is not significantly different from an AUC calculated using Tofts physiological models of 0.92 (95% CI [0.87 0.97]), as validated by a Wilcoxon signed rank test on each patient’s AUC (p = 0.19). The time required for calculation and feature extraction is 11.39 seconds (95% CI [10.95 11.82]) per patient using the Hilbert-based feature set, two orders of magnitude faster than the 1319 seconds (95% CI [1233 1404]) required for the Tofts parameter-based feature set (p<0.001). Hence, the features proposed herein appear useful for CAD systems integrated into clinical workflows where efficiency is important.
Proc. SPIE. 9418, Medical Imaging 2015: PACS and Imaging Informatics: Next Generation and Innovations
KEYWORDS: Medicine, Scanners, Digital imaging, Computed tomography, Optical character recognition, Radiology, Data communications, Digital Light Processing, Imaging informatics, Picture Archiving and Communication System
Our goal was to investigate the feasibility of an open-source, PACS-integrated, DICOM header-based tool that automatically provides granular data for monitoring of CT radiation exposure. To do so, we constructed a radiation exposure extraction engine (RE3) that is seamlessly connected to the PACS using the digital imaging and communications in medicine (DICOM) toolkit (DCMTK) and runs on the fly within the workflow. We evaluated RE3’s ability to determine the number of acquisitions and calculate the exposure metric dose length product (DLP) by comparing its output to the vendor dose pages. RE3 output closely correlated to the dose pages for both contiguously acquired exams (R2 =0.9987) and non-contiguously acquired exams (R2 =0.9994). RE3 is an open-source, automated radiation monitoring program to provide study-, series-, and slice-level radiation data.