OBJECTIVE. The purposes of this study were to compare the apparent
diffusion coefficient (ADC) of mucinous carcinoma of the breast with that of
other breast tumors and to analyze correlations between signal intensity on
diffusion-weighted images and the histologic features of mucinous
carcinoma.
SUBJECTS AND METHODS. Two hundred seventy-six patients with 277
lesions, including 15 mucinous carcinomas (13 pure type, two mixed type), 204
other malignant tumors, and 58 benign lesions, were examined with 1.5-T MRI at
b values of 0 and 1,500 s/mm2. The correlations between cellularity
and ADC, homogeneity of signal intensity on diffusion-weighted images, and
histopathologic findings were analyzed. The difference was statistically
significant (p < 0.05).
RESULTS. The mean ADC of mucinous carcinoma (1.8 ± 0.4
x 10-3 mm2/s) was statistically higher than that
of benign lesions (1.3± 0.3 x 10-3 mm2/s)
and other malignant tumors (0.9 ± 0.2 x 10-3
mm2/s) (p < 0.001). The ADC of pure type mucinous
carcinoma (1.8 ± 0.3 x 10-3 mm2/s) was
higher than that of mixed type mucinous carcinoma (1.2 ± 0.2 x
10-3 mm2/s) (p < 0.001) and other histologic
types (p > 0.05). The correlation between mean cellularity and the
ADC of mucinous carcinoma was significant (s = -0.754;
p = 0.001). The homogeneity of signal intensity on diffusion-weighted
images correlated with the homogeneity of histologic structures of mucinous
carcinoma (p < 0.001; = 0.826).
CONCLUSION. Mucinous carcinoma can be clearly differentiated from
other breast tumors on the basis of ADC. The low signal intensity of mucinous
carcinoma on diffusion-weighted images appears to reflect the presence of
mucin and low cellularity. High signal intensity on diffusion-weighted images
may reflect the presence of fibrovascular bundles, increased cell density, or
a combination of these features. |