THE ROLE OF DIFFUSION WEIGHTED MRI IN THE DIAGNOSIS AND FOLLOW UP OF BREAST CANCER
Yasmin Hassan Moussa;
Abstract
Breast cancer is the most common cancer and the second
leading cause of cancer-related mortality in women. Thus, prevention and screening have become important health issues. Early detection and treatment at proper time lead to good prognosis. A basic understanding of anatomy, histology and the complex underlying microscopic structures in which changes take place is important for understanding the pathologic process that occur. All are helpful for image interpretation.
There are many risk factors that affect breast cancer like gender, age, genetics and family and personal history where it commonly affects the left breast more than right and 4% of cases have bilateral primary tumors.
Breast carcinoma is classified into invasive and non invasive carcinoma where the most common one is IDC (76%) followed by DCIS and invasive lobular carcinoma.
MRI of the breast offers valuable information about many breast conditions that cannot be obtained by other imaging modalities, such as mammography or ultrasound. Its success is dependent on many fac¬tors, including injection of gadolinium contrast material, use of a high-field-strength magnet and appropriate timing of the dynamic se¬quences.
Diffusion weighted imaging (DWI) has been investigated as a means of overcoming the limitations of conventional MR imaging which is reliant on inherent unique tissue contrast mechanism .It is a reasonable choice being safe, quick, cheap and perfomed in the same session of a standard breast MRI examination but it is recommended to be be done before contrast enhancement to avoid inconsistency between studies.
DW imaging makes use of the variability of Brownian motion .In tissues with tightly packed cells, diffusion is restricted, the signal intensity increase and the ADC value becomes lower and vice versa.
Therfore it is reported to be useful for characterizing breast tumors and distinguishing malignant tissues from benign tissues.
The published ADC values of benign and malignant breast lesions vary between studies making it difficult to set an optimal value for differential diagnosis. In a study done by Tsushima et al. in 2009, the mean ADC value for malignant lesions was found to be 1.04 × 10–3 ± 0.29 × 10–3 mm2/s.
By this ADC cut off value DWI is able to achieve a sensitivity of 95% and specificity of 85% in differentiating between benign and malignant lesions.
Limitations of DWI due to low spatial resolution were discussed in this work .Abcess ,mastitis and hemorrhage may show high signal intensity and low ADC value, so could be misdiagnosed as a carcinoma.
Another application for DWI is to predict response to chemotherapy. Induction of successful apoptosis leads to increasing the diffusion between cells and so increase in ADC value more than before the NAC. Also it plays an important role in assessment of axillary lymph nodes where metastatic lymph nodes have a lower ADC value than benign involvement. In evaluation of peritumoral tissue, DWI increases the accuracy of DCE-MRI to reach 77%where the ADC value increases gradually from the innermost to the outermost layers of peritumoral tissue. Also, DWI is promising in differentiation between cancer recurrence and surgical scar where the former show lower ADC values.IN CONCLUSION, DWI as a diagnostic tool can increase the specificity of breast MR imaging and can reduce the number of false-positive results and associated unnecessary biopsies.
leading cause of cancer-related mortality in women. Thus, prevention and screening have become important health issues. Early detection and treatment at proper time lead to good prognosis. A basic understanding of anatomy, histology and the complex underlying microscopic structures in which changes take place is important for understanding the pathologic process that occur. All are helpful for image interpretation.
There are many risk factors that affect breast cancer like gender, age, genetics and family and personal history where it commonly affects the left breast more than right and 4% of cases have bilateral primary tumors.
Breast carcinoma is classified into invasive and non invasive carcinoma where the most common one is IDC (76%) followed by DCIS and invasive lobular carcinoma.
MRI of the breast offers valuable information about many breast conditions that cannot be obtained by other imaging modalities, such as mammography or ultrasound. Its success is dependent on many fac¬tors, including injection of gadolinium contrast material, use of a high-field-strength magnet and appropriate timing of the dynamic se¬quences.
Diffusion weighted imaging (DWI) has been investigated as a means of overcoming the limitations of conventional MR imaging which is reliant on inherent unique tissue contrast mechanism .It is a reasonable choice being safe, quick, cheap and perfomed in the same session of a standard breast MRI examination but it is recommended to be be done before contrast enhancement to avoid inconsistency between studies.
DW imaging makes use of the variability of Brownian motion .In tissues with tightly packed cells, diffusion is restricted, the signal intensity increase and the ADC value becomes lower and vice versa.
Therfore it is reported to be useful for characterizing breast tumors and distinguishing malignant tissues from benign tissues.
The published ADC values of benign and malignant breast lesions vary between studies making it difficult to set an optimal value for differential diagnosis. In a study done by Tsushima et al. in 2009, the mean ADC value for malignant lesions was found to be 1.04 × 10–3 ± 0.29 × 10–3 mm2/s.
By this ADC cut off value DWI is able to achieve a sensitivity of 95% and specificity of 85% in differentiating between benign and malignant lesions.
Limitations of DWI due to low spatial resolution were discussed in this work .Abcess ,mastitis and hemorrhage may show high signal intensity and low ADC value, so could be misdiagnosed as a carcinoma.
Another application for DWI is to predict response to chemotherapy. Induction of successful apoptosis leads to increasing the diffusion between cells and so increase in ADC value more than before the NAC. Also it plays an important role in assessment of axillary lymph nodes where metastatic lymph nodes have a lower ADC value than benign involvement. In evaluation of peritumoral tissue, DWI increases the accuracy of DCE-MRI to reach 77%where the ADC value increases gradually from the innermost to the outermost layers of peritumoral tissue. Also, DWI is promising in differentiation between cancer recurrence and surgical scar where the former show lower ADC values.IN CONCLUSION, DWI as a diagnostic tool can increase the specificity of breast MR imaging and can reduce the number of false-positive results and associated unnecessary biopsies.
Other data
| Title | THE ROLE OF DIFFUSION WEIGHTED MRI IN THE DIAGNOSIS AND FOLLOW UP OF BREAST CANCER | Other Titles | دور الانتشــار الجزيئــي بالرنيــن المغناطيسـي في تشخيص ومتابعة سرطان الثدي | Authors | Yasmin Hassan Moussa | Issue Date | 2014 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.