Dynamic Contrast-Enhanced MRI of the Breast: Quantitative Method for Kinetic Curve Type Assessment

Abstract

OBJECTIVE-The type of contrast enhancement kinetic curve (i.e., persistently enhancing, plateau, or washout) seen on dynamic contrast-enhanced MRI (DCE-MRI) of the breast is predictive of malignancy. Qualitative estimates of the type of curve are most commonly used for interpretation of DCE-MRI. The purpose of this study was to compare qualitative and quantitative methods for determining the type of contrast enhancement kinetic curve on DCE-MRI.MATERIALS AND METHODS-Ninety-six patients underwent breast DCE-MRI. The type of DCE-MRI kinetic curve was assessed qualitatively by three radiologists on two occasions. For quantitative assessment, the slope of the washout curve was calculated. Kappa statistics were used to determine inter-and intraobserver agreement for the qualitative method. Matched sample tables, the McNemar test, and receiver operating characteristic (ROC) curve statistics were used to compare quantitative versus qualitative methods for establishing or excluding malignancy.RESULTS-Seventy-eight lesions (77.2%) were malignant and 23 (22.8%) were benign. For the qualitative assessment, the intra-and interobserver agreement was good (κ = 0.76-0.88), with an area under the ROC curve (AUC) of 0.73-0.77. For the quantitative method, the highest AUC was 0.87, reflecting significantly higher diagnostic accuracies compared with qualitative assessment (p < 0.01 for the difference between the two methods).CONCLUSION-Quantitative assessment of the type of contrast enhancement kinetic curve on breast DCE-MRI resulted in significantly higher diagnostic performance for establishing or excluding malignancy compared with assessment based on the standard qualitative method. Keywords breast cancer; breast imaging; contrast-enhanced MRI; dynamic MRI; kinetic curve; washout Contrast-enhanced MRI carries very high sensitivity but moderate specificity for the diagnosis of breast cancer [1,2]. Dynamic contrast-enhanced MRI (DCE-MRI) has been widely used to improve the specificity of MRI in characterizing breast lesions [3][4][5][6][7]. The NIH Public Access Materials and Methods Clinical SubjectsMRI scans of 300 consecutive patients who presented to our facility for bilateral breast MRI from January 2007 to February 2008 were retrospectively reviewed. Patients were included in the study if they had a breast lesion or lesions at least 1 cm in diameter that had a pathologically proven diagnosis or 2 years of imaging follow-up accepted as a proof of benignity. This study was approved by our institutional review board and was compliant with HIPAA.Ninety-one patients met the inclusion criteria of the study. Patients were scanned on either a 1.5-T (48 patients) or a 3-T (48 patients) clinical MRI system (1.5-T Intera and 3-T Achieva, Philips Healthcare) using a bilateral dedicated phased-array breast coil (4-channel breast array coil, Invivo). The MRI protocol included 2 minutes of high-temporal-resolution imaging (15 seconds per acquisition) to capture the wash-in phase of contrast enhancement, high-spatial-resolution ...

Can semi-quantitative evaluation of uncertain (type II) time-intensity curves improve diagnosis in breast DCE-MRI?

“…The semi-quantitative assessment was inspired by the work of El Khouli et al [19]. Each TIC was classified on the basis of the difference between the percentage-enhancement at the last time point and the peak percentageenhancement: if the difference was in the range −5% to 5% the TIC was classified again as type II; for a difference greater than +5% the TIC was classified as type I; for a difference less than −5% the TIC was classified as type III.…”

“…The vascularisation of the malignant lesions resulting from neo-vessels, that are the basis of exponential tumour growth, is one of the major reasons that dynamic features of MRI have played a crucial role in breast cancer for a decade [7][8][9][10][11][12][13][14][15][16][17][18][19].…”

“…Breast lesion enhancement can be characterized by assessing the enhancement kinetic curves obtained by plotting the signal intensity values over time after contrast material injection with time-intensity curves (TICs) [4,19]. The classification of the TICs is operator dependent and some overlaps are evident between benign and malignant lesions [7].…”

“…Kinetic curve analysis can be performed qualitatively (visual inspection of the curve shape), semi-quantitatively (by means of empirical parameters of signal intensity changes as gradient of the upslope of enhancement curves, maximum signal intensity and wash-out gradient) or quantitatively through pharmacokinetic modelling techniques [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

“…The late patterns are defined as persistent, plateau and wash-out [4][5][6] and have been described by Kuhl [4]: type I (Ia-Ib) curve is a slow steady enhancement curve and is a strong indicator of benignancy (sensitivity and specificity of 52% and 71%); type III curve is associated with wash-out of signal intensity and is a strong predictor of malignancy (sensitivity and specificity of 20.5% and 90.4%); type II demonstrates plateau signal intensity and represents an intermediate probability of malignancy (sensitivity and specificity of 42.6% and 75%) [4][5]19].…”