Issues surrounding the detection of DCIS using MRI, and typical contrast enhancement patterns
The use of MRI in breast cancer screening is still somewhat controversial. MRI often reveals abnormalities with greater sensitivity than mammography, but the lack of specificity of the results more often than not leads to a biopsy anyways.
The main goal of breast cancer screening is to catch the cancer early, before it has a chance to spread. If breast cancer can be contained and treated as DCIS, the prognosis is almost always highly favorable.
There is a risk, however, that an overly aggressive and exhaustive approach to breast cancer screening, including the use of MRI, will lead to unnecessary tests and overtreatment. According to recent polls of radiologists working in the breast cancer area, there is generally no particular advantage or compelling need expressed regarding the use of MRI in breast cancer screening.
To clarify, even though statistics may show higher ‘discovery rates‘ for DCIS through the use of MRI, in terms of overall management, treatment, and cure rates, those who work in the field tend not to express any particular advantage to using MRI nor suggest its widespread, universal application.
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MRI is certainly beneficial in screening for breast cancer/DCIS in some situations
MRI has proven to be beneficial in the screening and detection of DCIS in high risk groups. Up to one half of screened breast cancers detected by MRI are not seen on mammography or discovered at clinical exams. Evidence also shows that women who carry the BRCA1 and BRCA2 mutations yield even a higher rate of DCIS detection using MRI.
Where DCIS is discovered following a biopsy, there is certainly good use for MRI when planning treatments or breast-conservation surgeries. Quite a few cases of DCIS are shown to be multifocal on MRI, even when mammography suggested otherwise. MRI is thought to be more reliable in the detection of DCIS in women with dense breast tissue, and may be a useful complementary modality in the evaluation of DCIS lesions that appear to have the strong potential to become infiltrative or invasive.
DCIS shows a number of typical patterns on contrast enhanced MRI
The enhancement pattern for DCIS is usually detected quite readily, although there is a fair bit of variability in presentation. DCIS quite often presents itself as a linear enhancement on MRI, and sometimes with a branching enhancement pattern.
DCIS linear contrast enhancement pattern
The image below shows a typical breast DCIS linear, contrast enhancement pattern, which would be found in about 18% of cases.
DCIS also presents in an ‘asymmetric’ contrast enhancement pattern and a linear-segmental contrast enhancement pattern
The asymmetric contrast enhancement pattern in the breast MRI below reveals DCIS in the retroareolar region.
The image below shows a linear and segmental contrast enhancement pattern, which is highly suggestive of DCIS.
The diffuse-stippled-segmental pattern of DCIS is the most common
The most frequent presentation of contrast enhanced DCIS is as a diffuse stippled segmental presentation. This pattern appears in 43% to 60% of all cases.
DCIS is more easily detected using bilateral contrast enhanced MRI
DCIS is much easier to detect on contrast enhanced breast MRI if both breast are scanned. The asymmetrical pattern of stippled, segmental, and diffuse contrast enhancement would be highly suggestive of DCIS.
Over 95% of DCIS lesion exhibit contrast enhancement, but specific types of enhancements cannot be consistently predicted or interpreted
In recent studies, over 95% of detected DCIS lesions show contrast enhancement with MRI. However, only about half of these meet the criteria for a ‘typical‘ cancer enhancement pattern, which is a strong, early, focal, ill-circumscribed, or ductal pattern.
Higher grade DCIS tends to have a more ill-defined enhancement pattern, while comedo DCIS tends to have a faster and more ductal pattern. However, there does not appear to be any significant and consistent different between high grade and low grade DCIS MRI contrast enhancement patterns, or between pure and microinvasive DCIS.
There in some support for the observation that malignant DCIS may tend to follow a duct, though there is certainly not enough evidence to make any generalizations at the present time.
A negative MRI cannot completely exclude the possibility of breast cancer
It should be noted that a negative MRI on a breast cancer screening does still not completely exclude the possibility of breast carcinoma at some level. Even though contrast enhanced MRI is an extremely sensitive tool for detecting breast cancer, there still remains the possibility, for a variety of reasons, the breast cancer can go undetected.
Invasive carcinomas smaller than 3-5 mm are sometimes missed. Lobular breast carcinoma, tubular breast carcinoma, and mucinous breast carcinoma and DCIS/LCIS may all still be present even if the MRI seems is interpreted as negative. However, since MRI is almost always used in conjunction with conventional mammography and ultrasound, the chances of missing a breast cancer diagnosis using all three imaging modalities is almost nil.
The image below shows a faintly enhancing tubular carcinoma in the delayed portion of the scan. The tubular breast cancer seen here might not be seen on an initial conventional breast MRI.
Statistics do show advantages to using MRI for DCIS detection
According to some recent studies, mammography detects DCIS (where present) in about 56% of cases, while the detection rate for MRI is around 92%.
Furthermore, MRI is able to detect almost 50% more high-grade DCIS presentations than conventional mammography. This would tend to suggest that MRI is the better modality for the detection of higher grade DCIS. However, these kinds of statistics tend to arise in specialized cancer centers, with the best modern equipment, and highly trained, experienced staff. In terms of mass-use with the general population, it is unlikely that the statistical advantage to MRI in detecting DCIS would be so high.
Microcalcifications are better detected and interpreted via conventional mammography
Mammography largely detects DCIS through the presence of microcalcifications on the X-ray image. MRI is actually not very effective at identifying microcalcifications.
On an MR image, calcium deposits can occasionally be seen as tiny signal voids, but they are not as reliably detected as with mammography. There is no proven advantage in the predictive value of contrast enhanced dynamic MRI over mammography when it comes to finding and interpreting microcalcifications.
Computer assisted DCIS detection is not as reliable as expert opinion
Other recent studies have explored the addition of computer-aided detection of DCIS. At the present time, computer-aided detection processes are less accurate in detecting DCIS than the opinion of an experienced breast cancer radiologist. This is largely due to the poorer sensitivity of DCIS lesions in general.
The overall sensitivity and specificty of MRI detected DCIS is really not that high
The overall sensitivity of MRI for the detection of DCIS is just under 80%, while the overall sensitivity of MRI in the detection of masses is over 92%. Where there are calcifications associated with a DCIS mass, the detection rate is only slightly higher (about 94%). The positive predictive value of MRI in the detection of DCIS can be estimated at around 84%, with a negative predictive value of only 71%.
It is also worth noting that the specificity of MRI in the detection of benign lesions is really lower than one would expect, at around 68%. The specificity of MRI screening in the detection of benign masses that show calcifications is actually very low, at around 33% only.
MRI detected DCIS may assist treatment, or may lead to unneccesary treatment
At the same time, even when MRI does detect DCIS during breast cancer screening, it often remains unclear how aggressively the cancer should be treated. Detection quite often leads to surgery of some kind, and quite frequently these surgeries prove to be unneccesary.
However, it is true that MRI can depict the extent and distribution of DCIS somewhat more effectively than conventional mammography or ultrasound, and this may offer certain advantages regarding treatment decisions.
Below are a couple common Q&A on MRI and DCIS:
- What does DCIS stand for, and what does it mean? DCIS stands for Ductal Carcinoma In Situ and it is the presence of abnormal cells inside a milk duct in the breast. DCIS is considered the earliest form of breast cancer. It is noninvasive, meaning it hasn’t spread out of the milk duct to invade other parts of the breast.
- When is DCIS usually found? DCIS is usually found during a mammogram done as part of breast cancer screening or when there is another concern with a woman’s breast.
- Is DCIS life threatening? No. Although it does require treatment to prevent the condition from becoming invasive.
- How is DCIS treated? Most women with DCIS are effectively treated with breast-conserving surgery and radiation.
- What are the symptoms? A breast lump and blood nipple discharge are the symptoms that may be caused. However, DCIS doesn’t normally cause any signs or symptoms in most cases.
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