What to Communicate with the Radiologist when Imaging the DIEP Flap Reconstructed Breast
A Guest blog from Danielle Carroll, MD
To image or not to image the reconstructed breast- that is the question…Well, actually the first question. I am not going to tackle that topic here, but Dr. Chrysopoulo discusses this in his article “Mammograms and MRI after Reconstruction- Are They Needed?” . However, if you decide to proceed with imaging follow-up, what is important for you to know about imaging the reconstructed breast, and how can you best convey your reconstruction status to the reading radiologist?
The reconstructed breast will undergo many changes over the first several years post reconstruction, some of which will be visible externally, some may only be seen by imaging. The two most important pieces of information to convey to the scheduler and/or technologist are 1. Your history of mastectomy with soft tissue reconstruction and 2. When the reconstruction took place. Additional helpful pieces of information include prior radiation treatment (including when you completed radiation therapy), if a nipple tattoo is present, and if you are experiencing any new or changing breast symptoms including new lumps or skin changes.
Before or during a breast imaging study, either a scheduler or technologist will ask you several questions related to your breast health. All of your answers will be recorded on a worksheet- and will be reviewed by the radiologist interpreting the exam. You should be asked if you have had any prior breast surgeries. You will likely respond that you have had a prior mastectomy with DIEP flap reconstruction. In all likelihood- you will want to elaborate on the intricacies of the DIEP flap procedure, and ensure that the technologist understands that this is different from a TRAM flap reconstruction- or any other soft tissue reconstruction currently or previously available. Although I appreciate that the decision to pursue one type of reconstruction over another was well researched and likely difficult, from a breast imaging perspective, the type of reconstruction is irrelevant. The imaging appearance of the soft tissue reconstructed breast is classic with little to no difference in appearance across the spectrum of soft tissue reconstructions. As the radiologist, I am not evaluating the intricacies of the various surgical techniques. I might note that there is muscle and fat in one type of reconstruction, or just fat in another type of reconstruction, but this will not be confused with recurrent cancer, which is what I am ultimately looking for.
The timing of your surgery is actually the most important detail you can provide. The dates of the original mastectomy and any subsequent surgeries if applicable is tremendously helpful. Many non-cancerous changes occur in the post-operative breast, and the appearance of these findings will evolve over time. Certain imaging findings are considered normal within the first 6-12 months following surgery, but a similar imaging appearance might be considered abnormal 3 years from reconstruction. Let’s discuss a few of these imaging findings:
Fibrosis is the body’s normal reaction to trauma- in this case surgery. Fibrosis can be followed mammographically as long as a baseline study post reconstruction is performed and no new breast symptoms are reported. If new breast changes are noted and a baseline study is not available, fibrosis can look just like a cancer on the mammogram. Ultrasound may be helpful, but is often not definitive in differentiating fibrosis from recurrent cancer. Fibrosis can have a mass-like appearance similar to a cancer on MRI within the first 6-12 months following reconstruction. The MRI features of fibrosis will evolve over time so that after about 12 months- the fibrosis is usually easily differentiated from a recurrent cancer.
Fat necrosis is an inflammatory process where fat cells die, or become necrotic, and the surrounding tissue exhibits fibrosis and inflammation. Fat necrosis occurs in 8-12% of DIEP flap reconstructions as reported by Pinel-Giroux et al. (RadioGraphics 2013 33:2, 435-453). Fat necrosis is not unique to DIEP flap reconstruction, also occuring in the other types of soft tissue reconstruction. Additionally, any blunt trauma or surgery can result in fat necrosis. Fat necrosis is most often diagnostic mammographically, and usually follows expected imaging changes over time on the mammogram. A baseline mammogram is not as important when evaluating fat necrosis as compared to fibrosis. The early mammographic appearance of fat necrosis may not be diagnostic, however fat necrosis seen on a mammogram several years after surgery is almost always diagnostic. If the radiologist is not certain that the imaging findings represent fat necrosis, MRI is the next best examination for clarification. In most cases, MRI will differentiate fat necrosis from a recurrent cancer. The ultrasound appearance of fat necrosis is quite variable, and is generally not used as an imaging tool to evaluate suspected fat necrosis.
For both fibrosis and fat necrosis, the radiologist is confident in the diagnosis in most cases. However, there are times when the imaging appearance is not quite what is expected, and recurrent cancer cannot be excluded. In these cases, a biopsy should be performed in order to establish a pathologic diagnosis.
Radiation therapy has a profound effect on the imaging appearance of the breast. Radiation therapy results in diffuse fibrosis, skin thickening, and breast edema. These changes are most pronounced in the first year following completion of therapy, but can persist for years after treatment. Informing the technologist of previous radiation therapy and the date of completion will help the radiologist to determine if these findings are expected post radiation changes.
Hematomas and seromas are both fluid collections that are commonly seen on imaging of the post reconstructed breast. Fluid collections may be evaluated with either breast ultrasound or MRI. Breast ultrasound is often used to ensure that the fluid collection is decreasing in size over time.
Nipple tattoos are not visible mammographically, however the material used in the tattoo results in an artifact by MRI. MRI technology is very susceptible to metal and any compound that contains a metallic substance. Even if the metal is safe to be imaged by MRI, the metal will result in a black area surrounding the metal- effectively masking the surrounding tissue. This black area is referred to as metal artifact. In the setting of nipple tattoos, the surrounding artifact is small, however it is helpful to know that the tattoo has been placed so that the radiologist can explain why the artifact is present.
Although the decision to image the soft tissue reconstructed breast should be made in conjunction with your surgeon’s recommendations, rest assured that the radiologist is looking for classic imaging features on the mammogram, ultrasound, and MRI examinations to make a diagnosis of expected post-surgical changes versus suspicion for recurrent cancer. The radiologist is not relying on the specific details of reconstruction to make a diagnosis. The imaging appearance of both non-cancerous changes in the breast and recurrent cancer are the same no matter the type of reconstruction. The important details to convey to the radiologist are that mastectomy has been performed, the date of mastectomy and any subsequent reconstruction surgeries, if you have undergone radiation therapy and when, and if a nipple tattoo has been placed. Any specific concerns including new lumps or skin changes should also be discussed with the scheduler and/or technologist. The answers to all of these questions will be noted on a worksheet for the radiologist to reference in order to make the best final diagnosis based on your specific circumstances.
About the author: Dr. Carroll is a board certified fellowship trained radiologist specializing in breast imaging. She practices in Southern Arizona with Arizona State Radiology. Follow Dr. Carroll on twitter @dcarrollmd. If you are interested in more topics related to radiology, breast imaging, and/or breast health, subscribe to Dr. Carroll’s blog, The Mammo Press.