In recent years, many cutting-edge radiology facilities that perform breast imaging have begun offering a new imaging technology called digital breast tomosynthesis (DBT) in addition to or in place of standard mammography exams.
A standard mammogram consists of typically two images per breast — a craniocaudal (CC) and a mediolateral-oblique (MLO). The problem with this approach is that x-rays provide a 2-D representations of a 3-D structure and leave large gaps where no medical imaging data is captured.
Traditional mammography exams also have several downsides, including the potential for false positives, which could result in an unpleasant and invasive biopsy.
Studies suggest that digital breast tomosynthesis not only improves cancer detection rates, it also decreases recall rates, especially in women with dense breast tissue.
Digital breast tomosynthesis takes multiple x-ray pictures from various angles, which are then converted into a 3-D image of the breast. During the scan, an x-ray tube moves in an arc of 15 to 50 degrees, typically acquiring 11 to 49 images per breast. These cross-sectional slices are then reconstructed to form a more complete representation of the breast, giving doctors better visibility of potential regions of interest.
However, tomosynthesis is not without its own drawbacks.
For one, tomosynthesis results in a massive increase in the size of medical imaging studies and leads to subsequent problems associated with image management. By going from four images — two per breast in a standard mammogram — to 100 or more, tomosynthesis studies can be as large as 4 gigabytes. That's up to 40 times larger than a typical breast imaging study.
With this massive space requirement, what is the best way to manage tomosynthesis images? Is storage and access in a cloud-based picture archiving and communications system (PACS) possible?
Tomosynthesis Requirements for Cloud PACS
Tomosynthesis presents significant challenges to a radiology practice that wants to utilize a cloud-based PACS, but these challenges are by no means insurmountable. By planning ahead and finding a vendor knowledgeable about these particular issues, your practice should be able to utilize a cloud-based PACS for your tomosynthesis images.
Planning for storing tomosynthesis imaging in the cloud is similar to the planning involved in using the cloud for storage of standard mammograms. For one, a strong, effective compression algorithm is an absolute must. Most knowledgeable professionals recommend lossless compression to ensure the integrity of the data is maintained.
In addition, the bandwidth speed of the practice's internet becomes much more important when considering uploading and downloading these massive images. The more important of the two — especially for enormous images like those taken in tomosynthesis studies — is really the download speed, not the upload speed. While uploads can occur at a much more leisurely pace, since these images can be made available right off of the modalities, it is the download speed that governs how quickly the physician can fetch prior images of the patient.
In order to have these prior images already in hand during an appointment, it may be necessary to plan ahead and download the relevant images for the day's patients in advance.
To get the most leverage from your internet bandwidth, an automated buffer system can be inserted to upload studies to the cloud whenever there's sufficient bandwidth, in whatever time period it takes. This makes the send process much easier to manage especially during the "off hours," when the facility is not using its bandwidth for other purposes.
Careful and considered planning enables practices to use the cloud for storage of tomosynthesis images. In fact, cloud-based PACS have an advantage when working with tomosynthesis images because storage is such a crucial consideration. Cloud vendors can provide customers with a dynamic amount of storage, so even though the images are very large, the storage will never be filled to capacity.
A final point to consider is to ensure that the viewer associated with the cloud PACS is approved for diagnostic use for mammography/tomosynthesis reading. Not all cloud PACS have an integrated medical image viewer that is approved by the FDA for diagnostic use with mammograms/tomosynthesis.
Mammography/tomosynthesis reading requires an additional certification beyond the standard FDA approval, so it is important to ask your vendor if the medical image viewer associated with their cloud PACS has the appropriate approvals required in your geography. It is also critical to understand the equipment calibration requirements for your monitor and workstations, as Mammography Quality and Safety Act (MQSA) standards may apply when viewing these images.
What You Need to Keep in Mind
Although tomosynthesis imaging is an exciting new development for radiology practices, it's important to be prepared in advance for its aggressive demands. Ensuring that your bandwidth is sufficient, that you take full advantage of compression algorithms and that you are using an approved medical image viewer can make the cloud a viable option for all of your breast imaging needs.