الفهرس 
Anatomy of the BreastOnly 14 pages are availabe for public view
 |  | from | 286 |  |  |
| | | from | 286 | | |
Abstract
Breast cancer is the most common malignancy that affects women worldwide and is a significant health care problem. Methods such as X-ray mammography, ultrasound and physical examination are often limited in sensitivity and specificity, especially in young women. MRI is increasingly being used for preoperative local staging, localization of multiple lesions and screening of high-risk patients, and it is an area of intense research.
When added to the standard evaluation in patients thought to have breast cancer, contrast-enhanced MRI using both a kinetic and morphologic analysis will often result in changes in recommended patient management, better treatment planning and detect many occult cancers.
Breast MRI has a very high sensitivity of greater than or equal to 90% for breast cancer and near 100% sensitivity for invasive breast carcinoma. Recent studies of the use of breast MRI in high risk groups, have reported a specificity of 93 to 99%.
Breast MR imaging has been successfully used to help detect mammographically and sonographically occult breast cancer in women with increased risk for breast cancer. MRI has been shown to be the most sensitive method of detecting cancer in women at familial risk of breast cancer.
Objective: The objective of our study was to evaluate the diagnostic validity of breast MRI in discriminating benign from malignant lesions in women with occult breast lesions who are at a high risk of developing breast cancer, with histopathologic findings and/or follow up used as the reference standard.
Methods: Contrast-enhanced bilateral breast MRI was performed on 100 women at high risk of developing breast cancer with indeterminate imaging findings by mammography and/or ultrasonography. Lesions detected by MRI that could represent potential malignancies in both breasts were evaluated. Morphologic assessment and kinetic analysis (contrast enhancement) were performed on each lesion using dedicated postprocessing and display software. Functional MR tools were used in about 60% of cases to help in the differential diagnosis between malignant and benign of suspicious lesions detected at conventional MRI.
All patients underwent clinical and radiological evaluation followed by Contrast-enhanced bilateral breast MRI using 1.5 tesla superconductive Philips scanner. The diagnostic images were evaluated as regard lesion morphology (size, shape, margin type, enhancement pattern), signal intensity parameters (time to peak enhancement, maximum slope of enhancement curve, washout), and the BIRADS categories.
Results of the contrast enhanced bilateral breast MRI of the 100 patients were all reported and compared with the histopathalogical results of surgery or biopsy and with the results of follow up of lesions that were not surgically removed or biopsied.
Results: A total of 100 patients presented with occult breast lesions were included in the study with age ranging from 22 to 67 years old. 12% of the patients were finally diagnosed as free of any current pathology, 56% of the studied population had benign findings, while 31% of the patients were diagnosed as malignant. (24 patients IDC, 4 patients Invasive Lobular Carcinoma, 1 patient Medullary carcinoma, 1 patient Mucinous carcinoma and 1patient DCIS.)
In our study population the sensitivity, specificity, positive and negative predictive values of mammography were found to be 51.6%, 88.4%, 66.7%, and 80.3% respectively. Overall accuracy of mammography was 77%.
Among the 24 cases diagnosed by Mammography as malignant or with irregular densities, 8 turned out to be benign by histopathological evaluation (false +ve), while among the 76 cases diagnosed by Mammography to be benign lesions or non-conclusive studies (dense), 15 were proved to be malignant by histopathological evaluation (false –ve). Among the 38 cases that had dense breasts, 12 cases turned out to have underlying malignant masses, 9 cases had underlying benign pathologies and the rest (17 cases) were free. All these lesions were readily identified in MRI.
The sensitivity, specificity, positive and negative predictive values of CE-MRI for occult breast lesions in high risk patients included in the study, were found to be 100%, 93%, 86%, and 100% respectively. Overall accuracy of MRI breast was 95%.
Among the 36 cases diagnosed by MRI as malignant, 5 turned out to be benign by histopathological evaluation (false +ve), while among the 64 cases diagnosed by MRI to be benign lesions, none were proved to be malignant by histopathological evaluation (no false –ve)
Therefore breast MRI had higher sensitivity than specificity but general speaking it is considered highly valid with high specificity also. We found that combining qualitative assessment of morphological appearance of lesion on post contrast study and time signal intensity curves with functional MR tools, which were utilized in about 60% of the study population, was useful for achieving high validity for breast MRI.
Our results agreed well with most of the previous studies mainly as regard the high sensitivity of MRI, however our results shows 100% sensitivity and higher specificity which is also more than specificity of mammography. This could be attributed to using functional MRI tools, mainly diffusion weighted images which was done in about 60% of the cases and helped to a great extent in highlighting the pathology among the normal enhancing glandular tissues.
Conclusions: from our study, we conclude that MR imaging of breast is a rapidly evolving modality of excellent sensitivity in detection of breast cancer. The basic drawback of this modality was low specificity for breast malignancy. However, multiple studies including this study have shown that with the improvement in equipment and technique there is gradual increase in specificity.
Generally speaking breast MRI is highly effective in detection and characterization of occult breast lesions in high risk population, with excellent sensitivity and high specificity. This is attributed to the advance in equipment, technique, development and implementation of interpretation guidelines and development of functional MRI tools which contributed to the improving validity of this modality. Also the superiority of MRI compared to mammography, which is more evident in high risk population, supports the use of MRI as an important tool in screening of asymptomatic high risk women.