Patterns of enhancement on breast MR images: interpretation and imaging pitfalls

Abstract

The role of dynamic contrast material-enhanced magnetic resonance (MR) imaging of the breast as an adjunct to the conventional techniques of mammography and ultrasonography has been established in numerous research studies. MR imaging improves the detection and characterization of primary and recurrent breast cancers and allows evaluation of the response to therapy. The breast imaging lexicon published by the American College of Radiology allows a standardized and consistent description of the morphologic and kinetic characteristics of breast lesions; however, there are many challenges in the interpretation of breast enhancement patterns and kinetics, and many imaging and interpretation pitfalls must be considered. New breast MR imaging techniques that are based on the use of molecular markers of malignancy may help improve lesion characterization. The margin characteristics of a lesion and the intensity of its enhancement at MR imaging 2 minutes or less after contrast material injection are currently considered the most important features for breast lesion diagnosis.

Figure 1

Benign features. (a, b) Contrast-enhanced T1-weighted fat-saturated gradient-echo (GRE) (repetition time msec/echo time msec, 20/4.5; flip angle, 30°) images from a 51-year-old woman show regional micronodular (<5 mm stippled or punctate) enhancement in fibrocystic breast tissue (a) and rimlike enhancement around a cyst (arrow in b) within a region of fibrocystic breast tissue. (c) T2-weighted (4000/90) fat-saturated image (same patient as in a and b) shows the cyst (arrow). Comparison of the contrast-enhanced images with the T2-weighted image is important to recognize the benign nature of these findings. (d) Contrast-enhanced T1-weighted GRE (20/4.5; flip angle, 30°) subtraction image from a 44-year-old woman shows an oval mass with smooth and lobular margins and enhancement with dark internal septa, typical of a fibroadenoma (arrow). (e) T2-weighted (4000/90) fat-saturated image (same patient as in d) shows increased signal intensity in the lesion (arrow) in comparison with that seen in d. Increased T2-weighted signal intensity is typical of a myxoid fibroadenoma in a woman of this age. In women older than 50 years, age-related sclerotic changes in fibroadenomas result in a greater prevalence of lesions with fibrotic low signal intensity, which reduces the diagnostic usefulness of the T2-weighted imaging characteristic.

Figure 2

Malignant features. (a) Contrast-enhanced T1-weighted fat-saturated GRE (20/4.5; flip angle, 30°) image shows two masses in the left breast of a 44-year-old woman, one with thin rimlike enhancement at the 4-o’clock position (arrowhead) and the other with heterogeneous enhancement and enhanced internal septa at the 2-o’clock position (arrow). (b) T2-weighted (4000/90) fat-saturated image (same patient as in a) shows low signal intensity in the portions of the masses that appeared enhanced in a. A central region of necrosis in the mass at the 4-o’clock position shows increased internal T2-weighted signal intensity. The masses proved to be poorly differentiated ductal carcinoma with necrosis and signet ring cell features. (c) Contrast-enhanced T1-weighted GRE (20/4.5; flip angle, 30°) subtraction image from a 42-year-old woman shows a spiculated margin in an infiltrating carcinoma with ductal and lobular features. (d) Contrast-enhanced T1-weighted fat-saturated GRE (20/4.5; flip angle, 30°) image from a 52-year-old woman shows a retroareolar mass (arrow) with an irregular margin and heterogeneous enhancement. The results of histologic analysis indicated infiltrating ductal carcinoma. (e) T2-weighted (4000/90) fat-saturated image (same patient as in d) shows the mass (arrow) with low signal intensity. Note the focal skin thickening and nipple retraction.

Figure 3

Type I enhancement curve in a lesion stable over 2 years. The patient, a 28-year-old woman, had contralateral breast cancer (Fig 6). (a) Contrast-enhanced T1-weighted GRE (20/4.5; flip angle, 30°) subtraction image shows an 8-mm-diameter mass (arrow) with minimal lobulation and enhancement. (b) T2-weighted (4000/90) fatsaturated image shows an area of high signal intensity (arrow) within the lesion. (c) Curve indicates progressive enhancement in the lesion. The vertical axis indicates the percentage of enhancement, and the horizontal axis indicates the time in seconds.

Figure 4

Type II curve in a multifocal and bilateral invasive lobular carcinoma in a 39-year-old woman. (a) Contrast-enhanced T1-weighted fat-saturated GRE (20/4.5; flip angle, 30°) image shows regional nonmass enhancement. (b) Color-coded map shows foci with the maximum slope of enhancement increase (red) after contrast material injection. Two foci were selected as regions of interest (ROIs). (c) Curves indicate plateau enhancement. The vertical axis indicates the percentage of enhancement, and the horizontal axis indicates the time in minutes.

Figure 5

Type III curve from multifocal infiltrating lobular carcinoma in a 40-year-old woman. (a) Contrast-enhanced T1-weighted fat-saturated GRE (20/4.5; flip angle, 30°) image shows regions of clumped nonmasslike enhancement in all four quadrants. (b) Colorcoded map of the maximum slope of enhancement shows three ROIs selected in areas of rapid peak enhancement (red). (c) Enhancement curves indicate early washout. The vertical axis indicates the percentage of enhancement, and the horizontal axis indicates the time in minutes.

Figure 6

Moderately to poorly differentiated palpable mass (infiltrating ductal carcinoma) in a 28-year-old woman, 3 months postpartum. (a) Contrast-enhanced T1-weighted fat-saturated GRE (20/4.5; flip angle, 30°) image shows an irregular mass with an irregular and spiculated margin, features typical of invasive carcinoma. (b) T2-weighted (4000/90) fat-saturated image shows a region of low signal intensity (arrows) in the portion of the mass that appears enhanced in a. (c) The enhancement curve is type III, with an early peak and delayed phase washout. The vertical axis indicates the percentage of enhancement, and the horizontal axis indicates the time in seconds.

Figure 7

Enhancement patterns in DCIS in four patients. DCIS may be manifested as stippled and clumped regional or segmental enhancement; linear and branching ductal enhancement; focal mass enhancement with spiculated, irregular, lobulated, or smooth margins; focal enhancement with a diameter of less than 5 mm; or no enhancement. (a) Segmental linear and reticular enhancement. (b) Linear enhancement. (c) Spiculated 1.5-cm mass within extensive sclerosing adenosis. (d) Small oval mass with smooth margins.

Figure 8

Enhancement patterns in invasive ductal carcinoma in four patients. (a) Lobular mass with smooth margins. (b) Mass with spiculated margins. (c) Lobular mass with irregular margins. (d) Irregular mass associated with clumped segmental enhancement.

Figure 9

Enhancement patterns in invasive lobular carcinoma in four patients. (a) Mass with spiculated margins. (b) Mass with rimlike enhancement and associated segmental clumped enhancement. (c) Irregular mass. (d) Nonmasslike regional moderate enhancement.

Figure 10

Infiltrating ductal carcinoma with micropapillary features in a 52-year-old woman. (a) Axial contrast-enhanced T1-weighted fat-saturated GRE (20/4.5; flip angle, 30°) image shows an intensely enhanced 10-mm mass. The dotted vertical line indicates the sagittal plane in b. The use of multiplanar coordinates allows precise localization of masses and correlation between contrast-enhanced images and T2-weighted images. (b) Sagittal T2-weighted (4000/90) fat-saturated image shows an area of low signal intensity characteristic of a malignancy (arrow). Note that the dotted line is the same as the vertical coordinate in a. (c) Color-coded map of the maximum slope of enhancement shows that peak enhancement was off center and not covered by the ROI that was selected in the center of the mass. (d) Enhancement curve for the ROI in c shows a type II pattern. The vertical axis indicates the percentage of enhancement, and the horizontal axis indicates the time in seconds. (e) Color-coded map of the maximum slope of enhancement shows the ROI repositioned in the area of peak enhancement. (f) Enhancement curve for the ROI in e shows a type III washout pattern. The vertical axis indicates the percentage of enhancement, and the horizontal axis indicates the time in seconds. For the assessment of enhancement kinetics, it is important to select an ROI in the portion of the tumor with maximum peak enhancement. When an ROI is randomly placed in a mass, the enhancement curve may be variable and yield lower specificity.

Figure 11

Invasive lobular carcinoma in a 43-year-old woman. Multiparametric ISODATA cluster analysis map shows overlap of sodium and proton MR spectroscopic data corresponding to the enhanced mass. In A., the contrast-enhanced image shows a heterogeneously enhanced mass with irregular margins. B., Metabolite maps of water, choline, and lipids. C., Sodium MR image and corresponding ISODATA feature map. Spectra show a choline concentration of 3.2 ppm with a signal-to-noise ratio of 10.6 and an approximately 50% increase in the tissue sodium concentration in the region of pathologically proved cancer.