Discrete signal processing of dynamic contrast‐enhanced MR imaging: Statistical validation and preliminary clinical application

Abstract

A high-resolution image-based method was developed to analyze dynamic contrast agent-enhanced magnetic resonance images quantitatively. This method determines the initial rate of contrast agent accumulation, the delayed rate of accumulation, and the maximum enhancement in each pixel. These three parameters allow characterization of the dynamic signal features. Simulated noisy test sets of dynamic enhancement curves have shown this method to yield a fast and accurate characterization of the dynamic signal. Clinical examples of both qualitative image parameter maps and quantitative statistical analysis of the parameter distributions demonstrated the quality and potential of the technique. The technique is designed to yield imaging and quantitative information on contrast agent accumulation that can be useful in detecting residual tumor and evaluating response to therapy, while requiring less than 7 minutes of imaging time and 5 minutes of processing time per study.

Dynamic MR imaging (DEMRI) of microcirculation in bone sarcoma

“…This map can be used for qualitative inspection to identify small foci of viable tumor. In addition, it is easy to display a parameter/volume histogram for the entire tumor and to provide a statistically valid summary measure of this distribution that is correlated to the percentage of necrosis (29,30).…”

“…Building on evidence that the early initial slope of the DEMRI signals provided some surrogate assessment of response in bone sarcoma, Reddick et al developed a method of more completely characterizing the DEMRI curves (30) and applied this method to a study of 19 patients with osteosarcoma (49). Three base variables were identified by this technique: an initial contrast accumulation rate (ICAR), a delayed contrast accumulation rate (DCAR), and a maximum enhancement (ME).…”

“…Several of these variables have also been noted as important sources of variance in empirical DEMRI studies. The more accurate empirical studies used standard injection sites (central lines with saline flush to ensure good mixing) or attempted to control bolus arrival time or compute it for each patient examination either by using a reference curve in some vascular compartment, such as femoral artery for pelvic or lower extremity lesions, or by computing it from the experimental S(t) curves for each pixel (30). In addition, the shape variables of the input function also can be shown to affect output measures (4,43).…”

Dynamic magnetic resonance imaging of regional contrast access as an additional prognostic factor in pediatric osteosarcoma

“…After selection of the longitudinal (usually coronal) section best exhibiting the tumor, 30 sequential fast low angle shot (FLASH) images (TR/TE ϭ 23/10 milliseconds, 40°flip angle, 256 phase encodes, 10-mm slice thickness, 40 -50-cm field of view, 2 acquisitions) were acquired over a 7-minute period before, during, and after a bolus injection of 0.1 mmol/kg gadopentetate dimeglumine, as described previously. 16,26 Dynamic MRI studies were performed concurrently with routine clinical MRI (longitudinal T1-weighted and short time inversion recovery images; transverse T2-weighted and contrast-enhanced T1-weighted images).…”

Non-Invasive Detection of Axillary Nodes by Contrast Enhanced Magnetic Resonance Imaging

“…For each ROI, the maximum slope and baseline intensity were determined. To search for the maximum slope, a five-point, 64-s, sliding window was applied to the first 3 min of the time-intensity curve (21). The window search method compensated for regional heterogeneity in the time point of initial uptake.…”