|Year : 2019 | Volume
| Issue : 1 | Page : 21-26
Role of magnetic resonance spectroscopy in evaluation of breast masses
Aya E Elkafas1, Rania E Ali2, Salah El-Dein A El-Gohary3, Usama E Ghieda2
1 Radiodiagnosis and Medical Imaging Department, Tanta Cancer Center, Faculty of Medicine, Tanta University, Tanta, Egypt
2 Department of Radiodiagnosis and Medical Imaging, Faculty of Medicine, Tanta University, Tanta, Egypt
3 Department of Oncology Surgery, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||06-May-2018|
|Date of Acceptance||13-Jan-2019|
|Date of Web Publication||17-Sep-2019|
Aya E Elkafas
Department of Radiodiagnosis and Medical Imaging, Tanta Cancer Center, Tanta, 31511 Gharbiya
Background Early detection followed by appropriate treatment is currently the most effective strategy to reduce breast cancer mortality. New techniques must provide more precise evaluation of the indeterminate lesions. Magnetic resonance spectroscopy (MRS) is one of the available new techniques on MRI. It represents a noninvasive and nonionizing method of characterizing a user-selected volume of tissue based on the metabolic (chemical) content.
Aim The aim was to assess the role of in-vivo proton MRS in diagnosis, characterization, and differentiation between benign and malignant breast masses.
Patients and methods In this study, 40 female patients were examined by MRI using the multiphase dynamic sequence and proton MRS using magnets of intensity field 1.5 Tesla systems. Single-voxel technique after adequate shimming was used.
Results Thirty (62.5%) cases were malignant (based on the presence of high choline peak in the spectrum) and 18 (37.5%) cases were benign (no choline peak). MRS has increased the specificity of dynamic MRI for diagnosis of probable lesion from 76.5 to 94.1%. False-positive results were found in one case, and false-negative results were found in two cases.
Conclusion In-vivo proton MRS is a powerful method for characterizing indeterminate breast lesions based on the presence of a high choline peak in the spectrum.
Keywords: breast mass, choline, magnetic resonance spectroscopy
|How to cite this article:|
Elkafas AE, Ali RE, El-Gohary SDA, Ghieda UE. Role of magnetic resonance spectroscopy in evaluation of breast masses. Tanta Med J 2019;47:21-6
|How to cite this URL:|
Elkafas AE, Ali RE, El-Gohary SDA, Ghieda UE. Role of magnetic resonance spectroscopy in evaluation of breast masses. Tanta Med J [serial online] 2019 [cited 2019 Nov 15];47:21-6. Available from: http://www.tdj.eg.net/text.asp?2019/47/1/21/267017
| Introduction|| |
Breast cancer remains a significant cause of morbidity and the second leading cause of cancer death in women. Early detection followed by appropriate treatment is currently the most effective strategy to reduce breast cancer mortality. MRI is increasingly being used in managing breast cancer, with more sensitivity at detecting recurrences than mammography ,.
In-vivo proton magnetic resonance spectroscopy (1H-MRS) represents a noninvasive and nonionizing method of characterizing a user-selected volume of tissue on the basis of the metabolic (chemical) content. It appears that 1H-MRS may have a clinical role as a complementary measurement to augment a breast MRI examination, demonstrated to be successful in the differentiation between benign and malignant breast lesions. The malignant breast tissues show elevated water-to-fat ratio and choline-containing compounds (total choline, tCho), and any effect of therapy on tissue viability or metabolism will be manifested as changes in these levels .
| Aim|| |
The purpose of this study was to assess the role of in-vivo proton MRS in diagnosis, characterization, and differentiation between benign and malignant breast masses.
| Patients and methods|| |
This prospective study was conducted in accordance with recommendations of local ethics committee of Tanta University, which approved it. Between December 2016 and December 2017, breast MRI with spectroscopy was performed for 40 patients with breast disease. All cases were females, and their age ranged between 28 and 66 years. All cases were histopathologically proven after biopsy.
MRI was performed using a 1.5 T system using the multiphase dynamic sequence and proton MRS. A double breast coil was used for MRI.
Before the administration of contrast material, bilateral sagittal fat-suppressed T2-weighted images (TR/TE, 5,600/59; matrix, 320×314; slice thickness, 4 mm) and coronal T1-weighted images were obtained.
Dynamic MRI was performed every minute for the following 7 min after injection of a bolus of Gd-DTPA (Magnevist) (0.1 mmol/kg). Both breasts were examined in the axial plane at 30 s, 1 min, 2 min, 3 min, 4 min, 5 min, and 6 min after contrast injection, correspondingly.
The parameters for dynamic MRI were as follows: 4.3/1.3; flip angle, 80°; field of view, 34 cm; matrix, 448×322; and slice thickness, 1 mm. The right and left breasts were examined in the sagittal plane.
After all the MRI sequences had been performed, single-voxel in-vivo proton MRS was performed using a point-resolved spectroscopy sequence. For voxel placement, coronal and sagittal contrast-enhanced T1-weighted MR images were used as scout images, and a voxel of interest was placed to include the lesion. Shimming was performed automatically first, followed by manual shimming on the water resonance for optimization of the homogeneity in each volume of interest. After the shimming procedure, spectra were acquired with water suppression by applying three chemical shift-selective excitation pulses, and by spectral suppression using dual band-selective inversion with gradient dephasing .
| Results|| |
In this prospective study, we had examined 40 patients with 48 masses. The mean age of our study’s patients was 43.24 years.
[Table 1] illustrates the histopathological diagnosis of the studied lesions (n=48). A total of 21 (43.8%) lesions were invasive ductal carcinoma, 13 lesions (27.1%) were fibroadenoma, approximately five lesions (10.4%) were invasive adenocarcinoma, and three lesions (6.3%) were invasive lobular carcinoma.
[Table 2] shows the dynamic postcontrast MR evaluation. A total of 40 patients were examined by multiparametric MRI of the breast. Overall, 48 lesions were detected, where 31.3% of the cases had benign lesions, whereas 64.6% of the cases had malignant ones. The indeterminate lesions represented 4.2% and were considered suspicious malignant lesions.
[Table 3] shows MRS of the studied lesions (n=48). Ten (20.8%) lesions had no peak on MRS study, and they were proven to be benign by histopathological examination. Eight (16.7%) lesions had a broad peak, and after histopathological examination, six (12.5%) were benign, whereas two (4.2%) lesions were malignant. However, 30 (62.5%) lesions yielded a tall peak, following histopathological examination, in which 29 (60.4%) lesions were malignant and one (2.1%) lesion was benign. Only the tall peak was considered a marker of malignancy. Absent and broad peaks were considered benign for MRS examination.
[Table 4] illustrates the false and true results of the MRI and MRS. MRI revealed 33 malignant lesions and 15 benign lesions. Four of the malignant lesions were later confirmed to be false positive, whereas two lesions were proved to be false negative after histopathological results. According to MRS imaging, 30 (62.5%) lesions were malignant whereas benign lesions were 18 (37.5%) lesions, as shown in [Table 3]. One lesion of the malignant lesions was proved to be a false positive, whereas two lesions were false negative after histopathological examination.
|Table 4 The false and true results of the MRI and magnetic resonance spectroscopy|
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[Table 5] illustrates the different statistical values of both MRI and MRS. The diagnostic sensitivity and specificity of 1H MRS for the 48 lesions were 93.5 and 94.1%, respectively. For the dynamic MRI without spectroscopy, the sensitivity and specificity were 93.5 and 76.5%, respectively ([Figure 1],[Figure 2],[Figure 3]).
|Table 5 The different statistical values of both magnetic resonance imaging and magnetic resonance spectroscopy|
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|Figure 1 (a) A 36-year-old woman presented with a right breast lump, and after conventional and DCE-MRI revealed a well-circumscribed oval-shaped mass lesion at the lower outer quadrant of the right breast, being homogenous after contrast enhancement. (b) Kinetic curve showed type I curve pattern. (c) MRS was negative for choline peak. It was a true-negative case for MRS, and the case was histopathologically proven as fibroadenoma. DCE-MRI, dynamic contrast-enhanced MRI; MRS, magnetic resonance spectroscopy.|
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|Figure 2 (a) A 41-year-old woman presented with a right breast lump, and after conventional and DCE-MRI revealed an ill-defined irregular shaped mass lesion involving the outer lower quadrant of the right breast, eliciting heterogeneous enhancement. (b) Kinetic curve showed type III curve pattern. (c) MRS was positive for choline peak. It was a true positive case for MRS, and the case was histopathologically proven as invasive ductal carcinoma grade II. DCE-MRI, dynamic contrast-enhanced MRI; MRS, magnetic resonance spectroscopy.|
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|Figure 3 (a) A 52-year-old woman with a history of right MRM for breast cancer presented with a left breast lump and after conventional and DCE-MRI revealed well-defined rounded lesion at the lower inner quadrant of the left breast, eliciting homogenous postcontrast enhancement. (b) Kinetic curve showed type II curve pattern. (c) MRS was positive for choline peak. It was a false negative for MRI and a true positive for MRS, and the case was histopathologically proven as invasive lobular carcinoma. DCE-MRI, dynamic contrast-enhanced MRI; MRS, magnetic resonance spectroscopy.|
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| Discussion|| |
The use of dynamic contrast-enhanced (DCE)-MRI in the assessment of breast cancer has become popular over the years. It has been used for local staging and screening high-risk patients. It is also a useful surveillance modality in breast cancer survivors and claimed to be more sensitive in detecting recurrences than mammography.
According to the histopathological results, most of the detected lesions were malignant (31 lesions, 64.6%) and only 17 (31.4%) lesions were benign. The most commonly detected malignancy was the invasive ductal carcinoma (43.8%), whereas the fibroadenoma was the most common detected benign lesions (27.1%). This finding is similar to the finding of Razek et al.  who detected IDC in 24% as the most frequent malignant lesion and fibroadenoma in 33% as the most frequent benign lesion.
It is essential to assess the margin and shape of the mass in the first postcontrast image to avoid the washout and the progressive enhancement of the surrounding breast tissue . According to Macura et al. , the mass margin is the most predictive feature of malignancy in the breast MR image, and when speculated margins are detected, malignancy should be expected.
In the present study, MRI revealed 33 malignant lesions and 15 benign lesions. Following the histopathological assessment, four of the 33 malignant lesions turned out to be a false positive and two turned out to be false negative. Statistical analysis revealed that the sensitivity and specificity of MRI in the present study were 93.5 and 76.5%, respectively. Razek et al.  demonstrated similar results. They found that the sensitivity and specificity of the MRI in their study were 93.6 and 77.9%, respectively. Moreover, Kuhl et al.  reported 92.3% sensitivity and 75% specificity of the MRI in their study.
The sensitivity of DCE-MRI of the breast is high at 91–100%; hence, its popularity is increasing over the time, especially for the high-risk cases . The differential enhancement between normal and malignant tissue on T1-weighted imaging is responsible for the high sensitivity of the DCE-MRI . The current study reported 93.5% sensitivity for the DCE-MRI.
However, the specificity of breast DCE-MRI is highly variable, ranging between 37 and 97% . Several factors might account for that wide range, including differences in the magnetic field strength, imaging parameters, patient selection criteria, and the histological differences of benign and malignant lesions. Including cancer, the contrast enhancement could be also detected in fibroadenomas, fibrocystic changes, mastitis, atypical hyperplasia, and lobular neoplasia . The specificity of the MRI in the present study was 76.5%.
MRS quantifies breast tissue levels of choline (Cho) compounds, which were found to be elevated in malignant lesions. According to MRS reports, the tall peak only is considered a marker for malignancy, whereas broad and absent peaks are considered benign .
The current study reported tall choline peak in MRS of 30 (62.5%) lesions, broad peak in 16.7%, and absent peak in 20.8%. According to the present study, MRS imaging revealed 30 malignant lesions and 18 benign lesions. Following the histopathological assessment, one of the 30 malignant lesions turned out to be a false positive and two turned out to be a false negative. Statistical analysis revealed that the sensitivity and specificity of MRS in the present study were 93.5 and 94.1%, respectively. So, the specificity of MRS was higher than MRI.
Similarly, Cecil et al.  and Yeung et al.  reported that the 1H MRS is highly sensitive (70–96%) in the in-vivo detection of malignant breast lesions. Moreover, Razek et al.  proved the MRS to be 96.5% sensitive and 95.5% specific regarding the detection of the breast cancer.
Moreover, Cecil et al.  and Yeung et al.  demonstrated comparable results, as they reported the MRS to be 100% sensitive and 89–100% specific in detecting breast malignancies.
On the contrary, Katz-Brull and colleagues demonstrated slightly different results. They reported the overall combined sensitivity and specificity of the MRS as 83 and 85%, respectively . Based on the result of this study, 1H MRS was a powerful method for characterizing of indeterminate breast lesions based on the presence of a high choline peak in the spectrum. The combined use of the contrast-enhanced MRI, the kinetic data, and the MRS prompted better characterization of indeterminate breast lesions.According to Haddadin et al.  adopting the detection of tCho as a cancer biomarker assumes a constant sensitivity across all measurements. However, it could be affected by several factors such as variation in pulse sequences, MR systems, breast coils, and voxel sizes. The present study supports the aforementioned information .
This study reports a higher incidence of the false-negative results, detected based on the assessment of tCho, in cases with small lesions than cases with larger lesions. This was explained by the study of Katz-Brull et al.  which proved that the sensitivity of the tCho assessment is directly proportional to the size of the tumor.
Moy et al.  reported, in accordance with the result of the present study, that the tCho was better detected in small lesions when 3 T was used than when 1.5 T was used.
| Conclusion|| |
The 1H-MRS is a powerful method for characterizing indeterminate breast lesions based on the presence of a high choline peak in the spectrum. The combined assessment of morphologic patterns on contrast-enhanced MRI and the kinetic data together with the MRS allows better characterization of indeterminate breast lesions.
In conclusion, although the MRS results were limited in this study because of the small number of cases relative to the other studies, the variation in pulse sequences, MR systems, breast coils, and voxel sizes, this study proved that a concomitant use of MRS and DCE-MRI 1H MRS is superior to either assessment alone. So, it is highly recommended to complement each DCE-MRI breast study with an MRS examination to get the best outcome.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]