Elsevier

European Journal of Radiology

Volume 82, Issue 12, December 2013, Pages e801-e806
European Journal of Radiology

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

https://doi.org/10.1016/j.ejrad.2013.09.001Get rights and content

Abstract

Purpose

To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast.

Materials and methods

The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm2 for DWI and b 0 and 1000 s/mm2 for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses.

Results

Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10−3 mm2/s (b 0–1000 s/mm2) and ≤1.12 × 10−3 mm2/s (b 0–1500 s/mm2), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10−3 mm2/s (b 1000 s/mm2), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm2 and MD with a b value of 0, 1000 s/mm2 (AUC = 0.82 ± 0.07).

Conclusion

ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision.

Introduction

Mammography and ultrasound are the basic imaging tools for breast radiology. The relatively low sensitivity of these tools resulted in demand for new imaging modalities. Dynamic contrast enhanced MRI with its high contrast resolution provided high sensitivity (90%) in the detection of breast cancer, however due to the low specificity (72%), it is still challenged to discriminate cancer from benign lesions [1].

Utilizing a new contrast mechanism, diffusion weighted imaging (DWI) provides a high sensitivity in the detection of changes in the microscopic cellular environment without the need for contrast injection [2]. DWI also offers a quantitative analysis, with the use of apparent diffusion coefficients (ADC). This quantifies Brownian Motion by reflecting the tissue cellularity and integrity of cell membranes. DWI has been used as a complementary technique to dynamic contrast enhanced MRI, which improved the diagnostic accuracy [2], [3].

Diffusion tensor imaging (DTI) is a new technique that uses additional gradients to detect the degree of diffusion in multiple directions (at least six). It measures the full diffusion tensor describing the degree of anisotropic water diffusion in the tissue, quantified with the parameters mean diffusivity (MD) and fractional anisotropy (FA). Similar to the ADC, MD reflects the average anisotropy, and FA describes the degree of anisotropy [4].

Numerous studies have been performed to assess the diagnostic performance of DWI in differentiating benign and malignant breast lesions. ADC's in malignant tumors were found to be significantly lower than those of benign lesions and adding DWI increased the diagnostic accuracy of conventional MRI [3], [5], [6], [7], [8]. More recently, a few studies with DTI have been performed to assess the efficacy of DTI parameters, MD and FA, in the normal breast tissue and lesions. MD's in malignant tumors were found to be significantly lower than that of benign lesions, whereas FA showed controversial results [9], [10]. Only a few previous DTI studies with 3 Tesla imaging analysing the normal breast [11] and breast lesions [12] were reported. Higher magnetic field imaging has the advantages of higher signal-to-noise ratio (SNR) which allows higher temporal and spatial resolution [2].

The aim of our study was to analyze DWI and DTI parameters in the normal breast tissue and breast lesions with a 3T imager. To our knowledge this is the first study to compare the diagnostic performances of the parameters in DWI and DTI in the differentiation of malignant from benign breast tumors.

Section snippets

Patients

The study was approved by the institutional review board. In addition to a blanket consent-that is routinely obtained from all patients in our institution for the use of their findings for research and education purposes, with the patient privacy secured-, an informed content was obtained for each biopsy procedure.

Eighty-four consecutive women referred to our MR unit for breast MRI from September 2012 to February 2013 were enrolled in this prospective study. Pediatric age group and patients

Diffusion parameters of the normal breast parenchyma

No calculation was done from the parenchyme of 6 patients who had predominantly fatty parenchyma. Mean ADC, MD and FA values of the normal breast parenchyma measured with ROI's placed on the contralateral breast fibroglandular tissue were given in Table 1. Mean ADC and MD were lower in postmenopausal women without statistical significance (p > 0.05).

Diffusion parameters of the lesions

Mean ADC, MD and FA values of the lesions and the normal parenchyma were shown in Table 2. ADC and MD values of the malignant lesions were

Discussion

Numerous studies have been performed with quantitative DWI of the breast for the last decade. In these studies, it was assumed that the water diffusion in the breast tissue was isotropic. However the organization of the ducts toward the nipple, suggested the idea of the presence of anisotropic water diffusion in the normal breast tissue which can be evaluated by DTI [9]. The majority of published DWI breast studies and DTI studies have been conducted with 1.5 T. Three T field strength provides

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