Contrast-enhanced MRI of the breast is probably the most sensitive method to detect breast pathology. It is best used to improve the sensitivity of mammography and sonography in selected patient groups with high breast cancer prevalence, where conventional methods are known to be less sensitive. Despite the high sensitivity of MRI, 5-12 % of invasive carcinomas are not recognized during MRI, because of lack of the typical criteria of carcinoma. MRI is probably inferior to mammography in detecting ductal in-situ carcinoma or very small carcinomas (< 3 mm), because the neo-angiogenesis induced by these small carcinomas is too faint to be detected by contrast-enhanced MRI. These tumours cannot be excluded by a normal MRI examination. MRI is non-specific as the distinction of benign and malignant breast lesions is unreliable. Only in selected cases (fat- or blood-containing lesions) may it improve the specificity of mammography and sonography. Mostly image-guided core biopsy is by far the most specific and least expensive method to establish a definitive diagnosis. For lesions exclusively detected by contrast-enhanced MRI, simple and reliable localisation devices are urgently needed. Presently accepted indications for MRI of the breast are: patients with silicone implants after mastectomy or augmentation mammoplasty (detection of recurrence/prosthesis rupture/silicon leakage); patients whose breasts are difficult to evaluate by combined mammography and sonography, who have had breast conservation therapy (local recurrence), or who have proven carcinoma in one breast (multifocality/-centricity or contralateral breast carcinoma) or proven axillary lymph node metastases from an unknown primary tumor, especially when these are hormone receptor positive; patients with extensive postoperative scarring. In the future, genetically defined high breast cancer risk may become an indication.

MRI of the breast: state of the art.

The aim of this study is to assess the usefulness of three-dimensional contrastenhanced magnetic resonance (MR) imaging, compared with galactography and ultrasonography (US). Fifty-five patients with bloody nipple discharge were investigated retrospectively. All patients were examined by galactography, ultrasonography and MR imaging. These three sets of findings were compared with the histopathological results from 16 intraductal biopsies, 3 excisional biopsies, 24 microdochectomies and 12 mastectomies. Contrast enhanced MR imaging demonstrated all malignant lesions including ductal carcinomain situ (DCIS). Four cases of DCIS were not visualized by ultrasonography and three malignant lesions were missed by galactography. In the MR study, segmental clumped enhancement (positive predictive value = 100%), and focal mass with smooth border (negative predictive value = 87.5%) were the statistically significant predictive factors. Among the three modalities, contrast-enhanced three-dimensional MR imaging demonstrated the location and distribution of the lesions most clearly, especially in cases of ductal carcinomain situ. It has the potential to be a useful diagnostic tool for patients with nipple discharge.

A comparison of mr imaging, galactography and ultrasonography in patients with nipple discharge

The evident advantage of high-field MR (magnetic resonance) scanners is their higher signal-to-noise ratio, which results in improved imaging. While no reliable efficacy studies exist that compare the diagnostic capabilities of low- versus high-field scanners, the adoption and acceptance of low-field MRI (magnetic resonance imaging) is subject to biases. On the other hand, the cost savings associated with low-field MRI hardware are obvious. The running costs of a non-superconductive low-field scanner show even greater differences in favor of low-field scanners. Patient anxiety and safety issues also reflect the advantages of low-field scanners. Recent technological developments in the realm of low-field MR scanners will lead to higher image quality, shorter scan times, and refined imaging protocols. Interventional and intraoperative use also supports the installation of low-field MR scanners. Utilization of low-field systems has the potential to enhance overall cost reductions with little or no loss of diagnostic performance.

https://www.jstage.jst.go.jp/article/mrms/3/1/3_1_27/_pdf

Utilization of low-field MR scanners

Breast MR imaging.

The purpose of the study was to compare standard analysis with pharmacokinetic analysis of time-intensity curves in dynamic three-dimensional (3D) MR mammography (MRM) for their capability of differentiating benign from malignant disease. Dynamic MRM of the whole breast was performed at 1.0 T using an axial fast low-angle shot (FLASH) 3D sequence. For the standard evaluation, the enhancement of the first minute (E1) and the slope of enhancement from minute 2 to 10 (SE2–10) were calculated. For pharmacokinetic analysis, the amplitude of enhancement (A), distribution time (t21), and elimination time (tel) were computed. Sixty-two histologically verified lesions were evaluated. The standard evaluation methods yielded a highly significant difference between benign and malignant disease for E1 (P = .0008) and SE2–10 (P = .0001). The pharmacokinetic parameters gained similarly significant P values (A, P = .0014; t21, P = .0024; tel, P = .0001). Both standard and pharmacokinetic analysis concordantly discriminated between benign and malignant lesions in discriminant analysis. Compared with standard analysis, a pharmacokinetic analysis of time-intensity curves is not beneficial for routine clinical diagnosis.

Dynamic 3d-mr mammography: Is there a benefit of sophisticated evaluation of enhancement curves for clinical routine?

PURPOSE To determine whether medium field strength (0.5 T) MR mammography is able to differentiate between benign and malignant lesions in the same way as a 1.5 T standard technique. MATERIAL In 40 consecutive female patients with nodular lesions, examinations were carried out at 1.5 T (2D-FFE, TR/TE/FA 200/3.9/80) and 0.5 T (3D-FFE, 24/3.4/40). RESULTS There was wide spread of the speed of enhancement of malignant tumours for both techniques (44%-145% with signal increase in the first minute of 42%-189%). In 15 out of 17 carcinomas, the rapidity of uptake and final degree of enhancement after contrast was higher during 0.5 T/3D measurements than it was for 1.5 T/2D images. Fibroadenomas and mastopathies showed similar enhancement characteristics for both techniques. Sharply defined "wash-out" was seen only in malignant lesions; it appeared ten times more frequently in the 0.5 T/3D examinations than at 1.5 T/2D. CONCLUSIONS The distinction between benign and malignant lesions can be made with more certainty using medium field strength and 3D-FFE sequence than using the 2D high-field standard technique.

MR-Mammographie bei 0,5 Tesla

PURPOSE To determine whether dynamic MR mammography is possible on midfield systems without loss of diagnostic sensitivity when compared to the standard highfield technique. MATERIALS AND METHODS 42 consecutive patients were examined twice: Once using the standard dynamic 2D gradient echo technique at 1.5 T; a second examination was performed on a 0.5 T system. For the midfield examinations a 3D sequence with optimized T1 contrast was used to compensate for the shorter T1 relaxation times at 0.5 T. Subtraction images were calculated to improve detectability of enhancing lesions. RESULTS Image quality was comparable on both systems. Mean enhancement of lesions was higher at 0.5 T/3D as compared to 1.5 T/2D (161% versus 112%). In malignant lesions, enhancement at 0.5 T/3D surpassed that at 1.5 T/2D in 88% of cases; average maximum signal intensity increase of cancers was significantly higher at 0.5 T/3D as compared to 1.5 T/2D (183% versus 108% relative to baseline). One satellite lesion of a recurrent carcinoma was detected on the 0.5 T/3D images only. CONCLUSION A 3D gradient echo pulse sequence can be used to compensate for the T1 shortening effect of the lower field strength. With a 3D sequence, sensitivity of MRM at 0.5 T is even superior to that of the standard 2D highfield technique.

MR mammography at 0.5 tesla. I. Comparison of image quality and sensitivity of MR mammography at 0.5 and 1.5 T

MR-Mammographie bei 0,5 Tesla. I: Vergleich von Bildqualität und Sensitivität der MR-Mammographie bei 0,5 und 1,5 T

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MR-Mammographie bei 0,5 Tesla

MR mammography at 0.5 tesla. I. Comparison of image quality and sensitivity of MR mammography at 0.5 and 1.5 T

MR-Mammographie bei 0,5 Tesla. I: Vergleich von Bildqualität und Sensitivität der MR-Mammographie bei 0,5 und 1,5 T