A persistent or flat TIC pattern on dynamic contrast-enhanced MR images indicates benign disease, but there is added value from including the ADC value in the evaluation of tumors that show a plateau or washout TIC pattern.

Purpose:To evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted MR imaging (DWI) in characterization of enhanced mass on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy. Materials and Methods:We analyzed consecutive breast MR images in 270 patients; however, 13 lesions in 93 patients were excluded based on our criteria. We analyzed tumor size, shape, margin, internal mass enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators of malignancy and calculate a predictive probability for malignancy. We added the corresponding categories to these prediction probabilities for malignancy and calculated diagnostic accuracy when we consider category 4b, 4c, and 5 lesions as malignant and category 4a, 3, and 2 lesions as benign. In a validation study, 75 enhancing lesions in 71 patients were examined consecutively.Results: Irregular margin, heterogeneous internal enhancement, rim enhancement, plateau time-intensity curve (TIC) pattern, and washout TIC pattern were the strongest indicators of malignancy as well as past studies, and ADC values less than 1.1 ϫ 10 Ϫ3 mm 2 /s were also the strongest indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 92% (56/61), 86% (12/14), 97% (56/58), 71% (12/17), and 91% (68/75), respectively. Conclusion:The combination of DWI and DCE-MRI could produce high diagnostic accuracy in the characterization of enhanced mass on breast MR imaging.

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Several MR findings can be used to help determine the histologic grade of phyllodes breast tumors.

Purpose: To determine whether passive muscle extension and contraction affect the proton diffusivity of the muscle. Materials and Methods:Five male subjects were examined. The fractional anisotropy (FA), and primary ( 1 ), secondary ( 2 ), and tertiary eigenvalues ( 3 ) of the right tibialis anterior and medial gastrocnemius muscles were compared between conditions of passive plantar flexion and passive dorsiflexion of the ankle joint. Results:In the tibialis anterior, FA, and 1 at dorsiflexion decreased significantly (P Ͻ 0.01 and P Ͻ 0.01, respectively) compared to those at plantar flexion, but 3 at dorsiflexion increased significantly (P ϭ 0.02). In the gastrocnemius, FA and 1 at dorsiflexion increased significantly (P Ͻ 0.01 and P Ͻ 0.01, respectively) compared to those at plantar flexion, but 3 at dorsiflexion decreased significantly (P Ͻ 0.01). The 2 value showed no significant change in either the tibialis anterior or medial gastrocnemius. Conclusion:The results indicate that passive muscle extension and contraction associated with passive joint movement would affect the proton diffusivity of the muscle. This alteration of proton diffusivity is probably associated with microscopic structural changes of the muscle. NUMEROUS STUDIES HAVE investigated muscle physiology using relaxation times and MRI (1-6). Recently, muscle studies using diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) have also been reported. Self-diffusion of cell water is affected by temperature and viscosity as well as barrier structures (i.e., cell membrane) (7-9). DWI thus provides microstructural information about the tissue. Galban et al (10) have demonstrated that diffusive parameters are sensitive to architectural and structural differences between functionally different muscles, and that there is a strong correlation between the 3 and the physiological cross-sectional area of the muscle, as well as a gender difference in water diffusivity within the muscle (11). Zaraiskaya et al (12) have observed significant differences in fractional anisotropy (FA) and in the apparent diffusion coefficient (ADC) of muscles between healthy volunteers and patients with muscle injury. Sinha et al (13) have shown the in vivo fiber tracking of muscle fibers using a 3T-MR system.There are some reports investigating the relation between muscle contraction (exercise) and diffusion parameters (14,15). But exercise changes temperature, blood flow and perfusion, and the changes of those factors affect proton diffusion; consequently, the implications of the results are complex and it is difficult to assess the relation between muscle microstructural change associated with contraction and proton diffusion.We hypothesized that the muscle microstructural change associated with contraction and extension; i.e., contraction, causes a decrease in sarcomere length and an increase in fiber and myofibril diameter affects proton diffusion and that these changes of proton diffusion can be detected with a clinical MR imager. The present study was perfo...