Diffusion-weighted imaging improves the diagnostic accuracy of conventional 3.0-T breast MR imaging

Abstract

Purpose: To evaluate the incremental value of diffusion-weighted (DW) imaging and apparent diffusion coefficient (ADC) mapping in relation to conventional breast magnetic resonance (MR) imaging in the characterization of benign versus malignant breast lesions at 3.0 T.

Materials and methods: This retrospective HIPAA-compliant study was approved by the institutional review board, with the requirement for informed patient consent waived. Of 550 consecutive patients who underwent bilateral breast MR imaging over a 10-month period, 93 women with 101 lesions met the following study inclusion criteria: They had undergone three-dimensional (3D) high-spatial-resolution T1-weighted contrast material-enhanced MR imaging, dynamic contrast-enhanced MR imaging, and DW imaging examinations at 3.0 T and either had received a pathologic analysis-proven diagnosis (96 lesions) or had lesion stability confirmed at more than 2 years of follow-up (five lesions). DW images were acquired with b values of 0 and 600 sec/mm(2). Regions of interest were drawn on ADC maps of breast lesions and normal glandular tissue. Morphologic features (margin, enhancement pattern), dynamic contrast-enhanced MR results (semiquantitative kinetic curve data), absolute ADCs, and glandular tissue-normalized ADCs were included in multivariate models to predict a diagnosis of benign versus malignant lesion.

Results: Forty-one (44%) of the 93 patients were premenopausal, and 52 (56%) were postmenopausal. Thirty-three (32.7%) of the 101 lesions were benign, and 68 (67.3%) were malignant. Normalized ADCs were significantly different between the benign (mean ADC, 1.1 x 10(-3) mm(2)/sec +/- 0.4 [standard deviation]) and malignant (mean ADC, 0.55 x 10(-3) mm(2)/sec +/- 0.16) lesions (P < .001). Adding normalized ADCs to the 3D T1-weighted and dynamic contrast-enhanced MR data improved the diagnostic performance of MR imaging: The area under the receiver operating characteristic curve improved from 0.89 to 0.98, and the false-positive rate decreased from 36% (nine of 25 lesions) to 24% (six of 25 lesions).

Conclusion: DW imaging with glandular tissue-normalized ADC assessment improves the characterization of breast lesions beyond the characterization achieved with conventional 3D T1-weighted and dynamic contrast-enhanced MR imaging at 3.0 T.

Figure 1:

Graph shows comparison of ROC curves for absolute versus normalized ADC. AUC for normalized ADC was significantly higher than that for absolute ADC (P < .01), indicating significant improvement in diagnostic performance after normalization to glandular tissue.

Figure 2:

Scatterplots of absolute and normalized ADCs of benign and malignant lesions in pre- and postmenopausal women. There was no significant difference in ADCs of benign and malignant lesions between pre- and postmenopausal women. There was wide overlap in absolute ADCs between benign and malignant lesions: Overlapping region included 71% (60 of 85) of lesions. Normalizing ADC to glandular tissue reduced overlap between benign and malignant lesions: Overlapping region included 16% (14 of 85) of lesions. Overlapping area (normalized ADCs, >0.7 and <1.0 × 10⁻³ mm²/sec) indicated indeterminate diagnosis: Values lower than 0.7 × 10⁻³ mm²/sec indicated probably malignant diagnosis, and values greater than 1.0 × 10⁻³ mm²/sec indicated probably benign diagnosis.

Figure 3:

Graph shows comparison between ROC curves for conventional MR imaging protocol (morphology plus dynamic contrast-enhanced [DCE] imaging data) and those for conventional MR imaging protocol with quantitative DW imaging (DWI) analysis added (with normalized ADCs). Adding DW imaging to conventional MR imaging protocol resulted in significantly higher AUC, indicating significantly improved diagnostic performance (P < .01).

Figure 4a:

Findings in right breast of 43-year-old woman with recent diagnosis of left-sided breast cancer. (a) Axial contrast-enhanced 3D T1-weighted high-spatial-resolution subtraction MR image (7.08/3.56, 10° flip angle) of right breast shows large (11 × 5 × 5-cm) spiculated enhancing mass lesion (arrow). (b) Kinetic curve for same lesion was categorized as type III (washout). (c) Axial ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) shows same lesion (arrow) with restricted diffusion. Absolute ADC of lesion was 1.3 × 10⁻³ mm²/sec, and glandular tissue–normalized ADC was 0.45 × 10⁻³ mm²/sec. Final histopathologic diagnosis was infiltrating ductal carcinoma with areas of ductal carcinoma in situ.

Figure 4b:

Findings in right breast of 43-year-old woman with recent diagnosis of left-sided breast cancer. (a) Axial contrast-enhanced 3D T1-weighted high-spatial-resolution subtraction MR image (7.08/3.56, 10° flip angle) of right breast shows large (11 × 5 × 5-cm) spiculated enhancing mass lesion (arrow). (b) Kinetic curve for same lesion was categorized as type III (washout). (c) Axial ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) shows same lesion (arrow) with restricted diffusion. Absolute ADC of lesion was 1.3 × 10⁻³ mm²/sec, and glandular tissue–normalized ADC was 0.45 × 10⁻³ mm²/sec. Final histopathologic diagnosis was infiltrating ductal carcinoma with areas of ductal carcinoma in situ.

Figure 4c:

Findings in right breast of 43-year-old woman with recent diagnosis of left-sided breast cancer. (a) Axial contrast-enhanced 3D T1-weighted high-spatial-resolution subtraction MR image (7.08/3.56, 10° flip angle) of right breast shows large (11 × 5 × 5-cm) spiculated enhancing mass lesion (arrow). (b) Kinetic curve for same lesion was categorized as type III (washout). (c) Axial ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) shows same lesion (arrow) with restricted diffusion. Absolute ADC of lesion was 1.3 × 10⁻³ mm²/sec, and glandular tissue–normalized ADC was 0.45 × 10⁻³ mm²/sec. Final histopathologic diagnosis was infiltrating ductal carcinoma with areas of ductal carcinoma in situ.

Figure 5a:

Findings in 49-year-old woman with family history–based high risk of breast cancer. (a) Axial contrast-enhanced 3D T1-weighted high-spatial-resolution subtraction MR image (7.08/3.56, 10° flip angle) of right breast shows lobulated intensely enhancing lesion (circled) 1 cm in diameter at 9 o’clock position. (b) Kinetic curve for same lesion was categorized as type III (washout), which suggests malignancy. (c) Axial ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) shows same lesion (circled) with nonrestricted diffusion. Absolute ADC of lesion was 3 × 10⁻³ mm²/sec, which was considered to indicate benign lesion with 1.3 or 1.6 × 10⁻³ mm²/sec ADC cutoff. Glandular tissue–normalized ADC was 1.5 × 10⁻³ mm²/sec, which was considered to indicate benign lesion with ADC cutoff values determined in current study. Final histopathologic diagnosis of lesion was fibrocystic changes.

Figure 5b:

Findings in 49-year-old woman with family history–based high risk of breast cancer. (a) Axial contrast-enhanced 3D T1-weighted high-spatial-resolution subtraction MR image (7.08/3.56, 10° flip angle) of right breast shows lobulated intensely enhancing lesion (circled) 1 cm in diameter at 9 o’clock position. (b) Kinetic curve for same lesion was categorized as type III (washout), which suggests malignancy. (c) Axial ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) shows same lesion (circled) with nonrestricted diffusion. Absolute ADC of lesion was 3 × 10⁻³ mm²/sec, which was considered to indicate benign lesion with 1.3 or 1.6 × 10⁻³ mm²/sec ADC cutoff. Glandular tissue–normalized ADC was 1.5 × 10⁻³ mm²/sec, which was considered to indicate benign lesion with ADC cutoff values determined in current study. Final histopathologic diagnosis of lesion was fibrocystic changes.

Figure 5c:

Findings in 49-year-old woman with family history–based high risk of breast cancer. (a) Axial contrast-enhanced 3D T1-weighted high-spatial-resolution subtraction MR image (7.08/3.56, 10° flip angle) of right breast shows lobulated intensely enhancing lesion (circled) 1 cm in diameter at 9 o’clock position. (b) Kinetic curve for same lesion was categorized as type III (washout), which suggests malignancy. (c) Axial ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) shows same lesion (circled) with nonrestricted diffusion. Absolute ADC of lesion was 3 × 10⁻³ mm²/sec, which was considered to indicate benign lesion with 1.3 or 1.6 × 10⁻³ mm²/sec ADC cutoff. Glandular tissue–normalized ADC was 1.5 × 10⁻³ mm²/sec, which was considered to indicate benign lesion with ADC cutoff values determined in current study. Final histopathologic diagnosis of lesion was fibrocystic changes.

Figure 6a:

Findings in 42-year-old woman with BRCA1 gene mutation—and thus high risk for breast cancer—and history of ovarian cancer. (a) Sagittal contrast-enhanced 3D T1-weighted high-spatial-resolution MR image (7.08/3.56,10° flip angle) shows spiculated enhancing lesion (arrow, circled region in c) suspicious for malignancy in lower central region of left breast. (b) Kinetic curve for same lesion was categorized as type Ia (persistent enhancement), which suggests benign status. (c) On sagittal color map generated from normalized ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) projected on contrast-enhanced 3D T1-weighted high-spatial-resolution MR image, blue color suggests low suspicion of malignancy; red, high suspicion of malignancy; and green, intermediate probability of malignancy, based on ADC cutoff values of 0.7 and 1.0 × 10⁻³ mm²/sec. Final histopathologic diagnosis of lesion was fibrocystic changes with sclerosing adenosis.

Figure 6b:

Findings in 42-year-old woman with BRCA1 gene mutation—and thus high risk for breast cancer—and history of ovarian cancer. (a) Sagittal contrast-enhanced 3D T1-weighted high-spatial-resolution MR image (7.08/3.56,10° flip angle) shows spiculated enhancing lesion (arrow, circled region in c) suspicious for malignancy in lower central region of left breast. (b) Kinetic curve for same lesion was categorized as type Ia (persistent enhancement), which suggests benign status. (c) On sagittal color map generated from normalized ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) projected on contrast-enhanced 3D T1-weighted high-spatial-resolution MR image, blue color suggests low suspicion of malignancy; red, high suspicion of malignancy; and green, intermediate probability of malignancy, based on ADC cutoff values of 0.7 and 1.0 × 10⁻³ mm²/sec. Final histopathologic diagnosis of lesion was fibrocystic changes with sclerosing adenosis.

Figure 6c:

Findings in 42-year-old woman with BRCA1 gene mutation—and thus high risk for breast cancer—and history of ovarian cancer. (a) Sagittal contrast-enhanced 3D T1-weighted high-spatial-resolution MR image (7.08/3.56,10° flip angle) shows spiculated enhancing lesion (arrow, circled region in c) suspicious for malignancy in lower central region of left breast. (b) Kinetic curve for same lesion was categorized as type Ia (persistent enhancement), which suggests benign status. (c) On sagittal color map generated from normalized ADC map (b values, 0 and 600 sec/mm²; 9548/64; 90° flip angle) projected on contrast-enhanced 3D T1-weighted high-spatial-resolution MR image, blue color suggests low suspicion of malignancy; red, high suspicion of malignancy; and green, intermediate probability of malignancy, based on ADC cutoff values of 0.7 and 1.0 × 10⁻³ mm²/sec. Final histopathologic diagnosis of lesion was fibrocystic changes with sclerosing adenosis.