Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 31  |  Issue : 2  |  Page : 502--507

Role of magnetic resonance imaging in differentiation of benign and malignant breast lesions


Adel M Elwakeel1, Suzan F Omar1, Aml R.A. Bayoumy2,  
1 Department of Diagnostic Radiology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Diagnostic Radiology, El-Reyad Hospital, Kafr El-Sheikh, Egypt

Correspondence Address:
Aml R.A. Bayoumy
Department of Diagnostic Radiology, El-Reyad Hospital, Kafr El-Sheikh
Egypt

Abstract

Objective This study was conducted to determine the role of MRI in differentiation of benign and malignant breast lesions. Background Breast MRI is an information-rich imaging modality that produces clear anatomic representation of soft tissue and also reflects underlying tissue dynamics. Patient and methods The current study included 30 female patients with clinically suspicious breast lesions. Their age ranged from 30 to 65 years. The study was conducted in Menoufia University Hospital. Cases were referred from General Surgery Department in Menoufia University Hospital. All cases were subjected to the following protocols: full history taking with special emphasis on age, parity, medications taken, previous allergic reactions, and family history of breast cancer, as well as clinical examination of both breasts to palpate any masses. An informed consent was obtained from patients included in the study. Sonomammography and dynamic contrast-enhanced (DCE) MRI were performed for all patients on high-field Toshiba Vantage1.5 T machine, respectively, in Menoufia University Hospital, Radiology Department. Results In this study the 27/30 enhanced breast lesions, their time–signal intensity curve were assessed, regarding their initial rise (slow, medium, or rapid) and their delayed phase (persistent, plateau, or washout). DCE-MRI revealed 16 (53.3%) lesions with progressive rising time/signal intensity curve (type I curve). Six (20%) lesions showed slow wash-in and slow washout with plateau curve (type II curve). Eight (26.7%) lesions showed rapid slope-up and rapid washout (type III curve). Three (10%) lesions were not enhanced. Conclusion The use of DCE-MRI decreases the number of breast biopsies taken, and it is very impressive in postsurgical follow-up (lumpectomy or mastectomy), as it can detect small lesions that can be missed by sonomammography.



How to cite this article:
Elwakeel AM, Omar SF, Bayoumy AR. Role of magnetic resonance imaging in differentiation of benign and malignant breast lesions.Menoufia Med J 2018;31:502-507


How to cite this URL:
Elwakeel AM, Omar SF, Bayoumy AR. Role of magnetic resonance imaging in differentiation of benign and malignant breast lesions. Menoufia Med J [serial online] 2018 [cited 2024 Mar 29 ];31:502-507
Available from: http://www.mmj.eg.net/text.asp?2018/31/2/502/239754


Full Text



 Introduction



The majority of the lesions that occur in the breast are benign. It is important to recognize benign lesions and distinguish them from breast cancer [1].

Breast cancer is now a significant cause of worldwide morbidity and mortality. Further, the increasing rate of breast cancer continues to be a major area of concern for both clinicians and researchers. Increased awareness in the affected population leads to more frequent physical examinations and diagnostic imaging procedures, which results in earlier diagnosis and hence improved prognosis [2].

Mammography has been proven to detect breast cancer at an early stage; other screening technologies also may contribute to the earlier detection of breast cancer, particularly in women under the age of 40 years for whom mammography is less sensitive, such as breast ultrasound (US) or MRI [3].

Breast US examination has been used for years as an adjunct to mammography for evaluating palpable or mammographically detected breast masses to determine whether a lesion represents a cyst or a solid mass [4].

Breast MRI has become an important tool for breast cancer detection and characterization. Dynamic contrast-enhanced (DCE)-MRI is highly sensitive for breast cancer, allowing the detection of malignancy that is occult on physical examination, mammography, and sonography [5].

Typical breast MRI exams involve a contrast-enhanced scan to highlight tissue with increased vascularity; it is a sensitive method for detecting malignancies, but it also produces many false positives [6].

 Patients and Methods



The patients gave an informed consent and the study was approved by the ethical committee of the hospital faculty of medicine menoufia university. All patients gave written informed consent before inclusion into the study. Patients with breast mass will undergo MRI breast with contrast to differentiate benign from malignant lesions.

Inclusion criteria

Any suspicious lesion diagnosed by sonomammography as breast imaging reporting and data system (BI-RADS) 3 and 4 was selected for MRI examination.

Exclusion criteria

Patients were excluded from the study in case of contraindications to perform MRI (patients with metallic foreign body or cardiac pacemakers, claustrophobic and uncooperative patients, patients who could not lie prone, patients with disturbed renal functions, and patients who refused the examination).

Methods

All patients were subjected to full history taking, clinical examination, and radiological imaging, including US examination, mammography, and MRI with contrast.

MRI and DCE-MRI were performed for the 30 patients included in the study with high-field Toshiba Vantage1.5 T machine in Menoufia University Hospital (Toshiba America Information Systems, Inc. Digital Products Division 9740 Irvine Boulevard Irvine, CA 92618). An informed consent was obtained from patients included in the study.

Patient preparation

Metallic objects related to the patient body including zippers and clasps were removed. Intravenous line was established for further gadolinium injection.

Patient positioning

The patient lay prone with breasts positioned onto the breast coil and checked to be as deep and as centered in the coil as possible, with the nipple facing straight down. The patient comfortability was checked and patients were instructed not to move during the period of examination.

Coronal T1-weighted spin echo sequence was carried out for localization purpose, followed by plain sequences using T1-weighted fast-spin echo sequence (TR = 501 ms, TE = 10 ms, FOV = 24 × 24 cm), in addition to T2-weighted fast-spin echo sequence (TR = 4131 ms, TE = 120 ms, FOV = 36 × 28 cm) and STIR-weighted fast-spin echo sequence (TR = 3660 ms, TE = 103 ms, FOV = 36 × 23.4 cm) in axial orientation and/or sagittal orientation.

A bolus of gadolinium (Gd-DTPA) was injected manually intravenously at a dose of 0.1 mmol/kg, followed by saline flush to ensure that contrast-enhanced images could be obtained immediately after contrast agent injection.

Image analysis

The MRIs were evaluated as follows: T1-weighted images, T2-weighted images, and STIR-weighted images were first examined to detect the presence of any abnormality and determination of MR appearance of the lesion (cystic, solid, or mixed); lesion interpretation took place as follows: its shape (regular or irregular), its border (well defined, ill defined, speculated), location of the lesion, signal intensity of the lesion, and the presence of lymph nodes.

DCE images were examined to detect the presence Dynamic behavior of the mass with evaluation of the percentage of enhancement, as well as the shape of time/signal intensity curve (type I, type II, or type III), was studied.

Time–intensity curve (kinetic curve)

Three types of time–intensity curves have been described: type I (steady enhancement), where a persistent increase in signal intensity is present beyond 2 min after contrast agent injection; type II (plateau), where the maximum signal intensity is achieved in the first 2 min and then remains fairly constant; and type III (washout), where the maximum signal intensity is achieved in the first 2 min and then decreases over time. It has been reported that benign lesions tend to exhibit a type I curve, and malignant lesions tend to exhibit a type III curve [Figure 1] and [Figure 2] [7].{Figure 1}{Figure 2}

 Results



The present study included 30 female patients, whose age ranged between 30 and 65 years; the mean age of those with benign lesions was 40.2 years and the mean age of those with malignant lesions was 48.4 years.

Malignant lesions were more common in patients whose age ranged from 40 to 50, as we found eight (57.1%) malignant lesions in this age range; no malignant lesions were detected in those under 30 years in our study.

The patients included in this study were selected according to their clinical presentation, the patient's past history, and the appearance of lesion in the US or mammography (suspicious lesions were selected).

From the 30 female patients included in this study, 19 (63.3%) patients came with mass sensation, 10 (30%) patients came with mass sensation and also past history of lumpectomy/mastectomy, and only one (6.7%) patient came with tender breast with past history of lumpectomy.

All the 30 patients included in the study, whose US and/or mammography were suspicious besides their suspicious past history, were referred for MRI examination. Description of MRI findings using BI-RADS included the lesion type: whether they were mass or nonmass lesions. Regarding the mass lesions, the description included basic morphological criteria of solid mass lesions including shape, margin, mass enhancement, and the kinetic curve assessment [Figure 3]. The number of mass lesions in our study was 27 lesions.{Figure 3}

The malignant lesions were more commonly seen in the upper outer quadrant and in the retroareolar region of the breast – eight (57.1%) lesions and four (28.6%) lesions, respectively – followed by two (14.3%) lesions in the lower inner quadrant. As regards benign lesions, six (37.5%) lesions were detected in the retroareolar region, six (37.5%) lesions are seen in the upper outer quadrant and three (18.75%) lesions in the lower inner quadrant, and one (6.25%) lesion in the lower outer quadrant.

There are three (10%) nonmass lesions in the study. The BI-RADS description applied for the nonmass lesions included distribution modifiers and the internal enhancement characteristics [Figure 4].{Figure 4}

The number of lesions that were categorized by US and/or mammography as BI-RADS category 3 were 22 (73.3%) lesions, 16 (53.3%) lesions proved to be benign, and six (2%) lesions proved to be malignant. The number of lesions that were categorized by sonomammography as BI-RADS category 4 were eight (26.7%) lesions, all of which were malignant.

DCE-MRI showed 30 mass and nonmass breast lesions; 13 (81.25%) lesions showed homogenous enhancement, all of which were benign; eight (57.2%) showed heterogeneous enhancement, all of which were malignant; three (21.4%) lesions showed rim enhancement, all of which were malignant; three (21.4%) lesions were not enhanced, all of which were benign.

In this study the 27 enhanced breast lesions, their time–signal intensity curve were assessed, also initial rise (slow, medium, or rapid) and their delayed phase (persistent, plateau, or washout) were also assessed. DCE-MRI revealed 16 (53.3%) lesions with progressive rising time/signal intensity curve (type I curve). Six (20%) lesions showed slow wash-in and slow washout with plateau curve (type II curve). Eight (26.7%) lesions showed rapid slope-up and rapid washout (type III curve). Three (10%) lesions were not enhanced.

 Discussion



DCE-MRI of the breast has been reported to improve detectability of cancer in many studies [8].

DCE-MRI of the breast has a high ability for breast lesion detection. DCE-MRI is also more accurate than mammography or US for the delineation of the extent of disease in patients with a recent diagnosis of cancer but limited ability for discrimination between benign and malignant lesions [9].

Moreover, DCE-MRI is much more expensive than other techniques, and it cannot be used for patients with contraindication for contrast media (e.g. patients with renal dysfunction or previous reactions to contrast agents) [10].

The assessment of breast lesions on MRI is based on the morphological criteria, enhancement kinetic pattern, and the T2 characteristic of breast lesions. Characterization of the detected lesions can be difficult, as imaging features have been shown to demonstrate considerable overlap between benign and malignant lesions. Hence, in equivocal circumstances, an additional feature to characterize suspicious lesions could be helpful to decrease the number of invasive breast procedures [11].

We conducted a study of 30 patients with 30 breast lesions to evaluate the role of DCE-MRI in the probably benign and suspicious breast lesions after mammographic and/or ultrasonographic examinations.

The patients included in this study were selected according to their clinical presentation, the patient's past history, and the appearance of lesion in the US or mammography (suspicious lesions were selected).

The age of our patients ranged between 30 and 65 years. The age of patients is younger in cases with benign lesions ranged between 30 and 55 years with a mean age of 40.2 years. The age of patients is older in cases with malignant lesions, ranging between 35 and 62 years with a mean age of 48.4 years.

From the 30 female patients included in the study, 19 patients came with mass sensation, 10 patients came with mass sensation and also past history of lumpectomy/mastectomy, and only one patient came with tender breast and past history of lumpectomy/mastectomy.

In the study conducted by Lee [12], it was found that the breast cancer is more frequent in the upper outer quadrant of the breast, which may be because more breast tissues are present in this quadrant or because of the overuse of underarm cosmetics; in the present study, it was also found that the malignant lesions were more in the upper outer quadrant and also in the retroareolar lesions.

Mammographic and US evaluation of the lesions were based on BI-RADS with classification of these lesions into BI-RADS 3 and BI-RADS 4, which were our main concern in this study and were encountered in 22 and eight lesions, respectively.

All the 30 patients included in the study were referred for MRI examination. Description of MRI findings using BI-RADS included the lesion type: whether they were mass or nonmass lesions. Regarding the mass lesions, the description included basic morphological criteria of solid mass lesions, including shape, margin, mass enhancement, and the kinetic curve assessment, and for nonmass lesions distribution modifiers and the internal enhancement characteristics.

In this study, it was found that the mass lesions with smooth margin (well defined) were 16 lesions and all were benign, whereas the lesions with irregular and speculated margin were all malignant. This is comparable to the study of Macura et al. [13], who reported that the margin description of a focal mass is the most predictive feature of the breast MRI interpretation and speculated margin are more suspicious for carcinoma.

There were 22 breast lesions that were assigned by sonomammography as BI-RADS 3, 16 lesions downgraded by DCE-MRI to BI-RADS 2, and six lesions upgraded to BI-RADS 4b. There were eight breast lesions that were assigned by sonomammography as BI-RADS 4, and they were upgraded to BI-RADS 5.

Some of the most powerful diagnostic criteria for the differentiation of benign and malignant tumors belong to internal enhancement of a focal mass, as described by Rausch DR et al. [10].

Shah SK et al. [14] reported that the most frequent morphological finding among the malignant lesions was heterogeneous internal enhancement.

In this study, DCE-MRI of mass lesions was done, which revealed 27 enhanced lesions and lesions and three nonenhanced lesions; 13 lesions had homogeneous enhancement, all of which were benign; and the other three nonenhanced lesions were benign also. The lesions with heterogeneous enhancement were eight lesions, and all were malignant. In the nonmass lesions in the present study, three lesions were with focal area of enhancement, whereas three lesions were with rim enhancement. In the present study, in case of mass-like enhancement, it was found that the heterogeneous enhancement was indicative of malignant lesions, whereas homogeneous enhancement is likely to occur in benign lesions. However, for nonmass lesions there are no specific criteria for the enhancement pattern, and this confirms the study conducted by Tozaki et al. [14].

Tozaki M et al. [15] reported that using the enhancement pattern in differentiation between benign and malignant lesions is often difficult with non-mass-like enhancement, as there is no standardized method for interpreting them.

In this study, after evaluation of the morphologic characteristics of each lesion, its dynamic behavior with quantitative analysis of signal intensity (measured by means of computer manipulated region of interest), as well as assessment of the shape of the time/signal intensity curve, was done.

In the present study, DCE-MRI time–signal intensity curve revealed that 16 lesions showed progressive raising curve (type I curve), and by follow-up the 16 lesions were benign. Six lesions showed plateau curve (type II curve), and all the six lesions were malignant. Eight lesions showed rapid washout (type III curve), and all were proven by histopathology as malignant; there were three nonenhanced lesions.

This is comparable to many studies that reported the importance of the curve shape in differentiating between malignant and benign lesions. Imamura T et al. [16] reported that the use of time–signal intensity curves resulted in markedly higher discrimination between benign and malignant lesions. Type III curve is more suspicious for malignancy, as reported by Orel SG et al. [17], whereas persistent curves are associated with benign lesions. Plateau curves are indicative of either malignant or benign lesions, as reported by Ikeda DM et al. [18].

When the ability of the MRI to detect the breast lesions is high, its ability for discrimination between benign and malignant lesions is low. The parameters that are capable of increasing its ability for discrimination are the kinetic and morphological values of the lesion and the diffusion-weighted imaging. All three parameters had insufficiencies with respect to the differentiation of the benign and malignant lesions, as described by Schnall MD et al. [19].

In the study, the detected breast lesions were classified according to their criteria on unenhanced MRI into benign and malignant lesions, as described by Kuroki-Suzuki et al. [20].

 Conclusion



MRI is an imaging tool that has been proven to decrease false negative cases diagnosed by sonomammography; MRI also has the ability to detect the lesions not seen on sonomammography, and this will help save life of the patients.

The DCE-MRI has a high ability for breast cancer detection, and the use of MRI (DCE-MRI) decreases the number of breast biopsies taken and it is very impressive in postsurgical follow-up (lumpectomy or mastectomy), as it can detect small lesions that can be missed by sonomammography in the delineation of the extent of disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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