Incorporating Automated Breast Ultrasound Screening into Routine Clinical Practice

This is the second of a two-part series. Last week, Dr. Dean explored the clinical benefits of ABUS.

At RSNA 2011 there were dozens of posters and presentations focused on breast density and the use of breast ultrasound to improve the early detection of cancer. A number of large studies, including ACRIN 6666, continue to bolster the scientific platform validating the use of breast ultrasound to find mammographically occult cancers. So, with published studies from some of the nation’s leading breast imaging experts, why hasn’t breast ultrasound screening been incorporated into routine clinical practice?

In their paper, “The CT Experiment: The Role of Ultrasound Screening in Dense Breasts,” Weigert and Steenberger conducted a retrospective chart review of five Connecticut radiology practices with more than 50,000 mammograms and more than 8,000 screening ultrasounds where approximately half received follow up breast ultrasound exams. While the results clearly demonstrated that breast ultrasound is effective in finding cancers missed by mammography, the researchers raised practical questions about the implementation of breast ultrasound screening, such as scheduling, technology factors, physician supervision, as well as protocols for determining true findings versus false positives. 

In my first article, I detailed the clinical benefits of implementing an automated breast ultrasound screening (ABUS) program, namely the goal of reducing interval cancers being missed by using mammography alone in women with dense breast tissue. Here, I’ll examine real and perceived barriers to screening with ABUS, including clinical and technical workflow, training, and density notification.

Barrier: Breast Ultrasound Takes Too Much Time

Few radiologists argue that breast ultrasound has clinical benefits, particularly when focused on women with dense breasts. Studies presented at RSNA demonstrated that ABUS increased the yield of invasive cancers found, and that the average size of the cancers found was smaller. Despite these results, many radiologists are concerned that breast ultrasound screening will take too much time.  

Chart source: Kelly, KM, Dean, J, Comulada WS, Sung-Jae L: "Breast Cancer Detection Using Automated Whole Breast Ultrasound and Mammography in Radiographically Dense Breasts," Eur Radiol (2010) 20: 734-742

Ultrasound is a proven breast imaging tool that has been used for diagnostic purposes for years. However, handheld ultrasound (HHUS) is operator-dependent, which can result in variable quality and inconsistent exams. Additionally, it is difficult to consider HHUS true screening as I believe the patient influences acquisition and the study quickly shifts from detection-based screening to a diagnostic exam. It is natural to be distracted when the patient is watching with intense interest as you interrogate specific areas. 

From a time perspective, physician-performed HHUS exams averaged 20 minutes in the ACRIN study. In routine practice, it is probably closer to 20 to 30 minutes. Using trained non-physician personnel that understand patient positioning and the anatomy of the breast as seen on ultrasound, ABUS has the potential to dramatically improve technical workflow.

In our practice, acquisition of a normal ABUS exam takes about 15 minutes and we book ABUS exams in 30-minute increments. This gives us ample time to prep the patient, set up the exam room, conduct the ABUS exam, and clean up to prepare the room for the next patient.

Barrier: I Don’t Know How to Interpret ABUS Exams

I have read more than 8,000 automated breast ultrasound exams since 2005 and would consider myself to be an experienced reader. However, when I recently served as a reader in the U-Systems ROC Reader Study, I participated in a training program designed to help accurately read ABUS exams faster.

Users start with a self study component to get oriented to ABUS images and software, which is followed by a 90-minute peer-to-peer web conference where trainees review cases with experienced ABUS experts. Finally, users attend an eight hour peer-to-peer workshop where they read 100 cases and get feedback from an expert. The results of this training program have been that users accurately read ABUS cases faster with repeatability, reproducibility and consistent outcomes.

In addition to improving the accuracy of the interpretations, clinical workflow can show tremendous improvement as a result of a training program. Before the peer-to-peer workshop, the average read time was about 15 minutes per case for radiologists in the U-Systems Reader Study. After the training, average review time decreased to about three minutes for a normal somo•v® ABUS case.

Additional breast ultrasound courses that include Sonocine and U-Systems’ somo•v® are available, and I highly recommend attendance at a formal course before starting an ABUS program.

Barrier: My Practice Can’t Handle ABUS Clinical Workflow

Although three minutes is longer than the average one- to two-minute read of a normal handheld breast ultrasound, with the ABUS exam the radiologist is able to review the entire data set, not just the few images selected for review by the technologist. This provides the ability to interrogate suspicious areas or quickly rule out normal findings, resulting in greater diagnostic confidence. 

Additionally, since the entire data set is available, ABUS exams can be batch read without the need to hold the patient in case the radiologist needs additional views or images not acquired by the technologist. In HHUS, the technologist essentially performs a diagnostic process while conducting the study and selecting sample images for review. You, as a radiologist must decide if you’re comfortable with this process. If your technologist does not recognize and document the abnormality, you will never know it is there.

Implementing Breast Ultrasound Screening

Now that we’ve established that ABUS improves technical workflow and provides consistent, reliable coverage of breast tissue for improved image quality and diagnostic confidence, how do you implement a breast ultrasound screening program without disrupting your workflow and productivity?

Barrier: Higher Recall Rate

As with any new modality or system, you should expect a learning curve as you start offering automated breast ultrasound exams. Initially, you will question more findings than you would on HHUS and your recall rate will be higher as you learn to rule out incidental findings, such as edge artifacts or nipple shadows. You can accelerate your learning curve by correlating immediately with HHUS for the first few weeks. To facilitate this, review the ABUS exams before patients leave, and allow enough time for HHUS in case you want to verify your findings.    

As I mentioned in the first article, I don’t recommend a biopsy on any screening study without a work up, whether it is a mammogram or ultrasound. If findings from screening studies are carefully worked up the PPV should be the same no matter how you initially identified the lesion. While recall rates for screening ABUS may always be higher than mammography, the increase is proportional to the additional cancers found.

Educating Patients and Referring Physicians

You may experience cost resistance from patients at first as there is no formal reimbursement for ABUS exams. However, as you begin to identify cancers with ABUS that were missed on mammography, word will spread. Since 2005, we have identified more than 30 patients with mammographically occult cancers using ABUS, and we have found that women are willing to pay for care when they understand the value.

Physicians have been very accepting of ABUS studies, as I make a point to personally call referring physicians when mammographically occult cancers are detected in their patients using ultrasound. I also am open about presenting these cases at tumor boards, when appropriate and with the patients’ permission, and I list on pathology referral forms “ultrasound-detected mass” when appropriate, just as I would list “suspicious microcalcifications” when a stereotactic biopsy specimen is submitted.

Barrier: Referring Physicians Will Be Upset if We Talk to Women about Density

With the goal of empowering women with the information they need to better protect their health, we have notified patients about breast density since 2005. In nearly eight years we have not received a single complaint from referring physicians about informing patients about breast density. Despite the widely publicized political opposition to Density Inform legislation in California, we have experienced nothing but strong support from our referring physicians. In fact, we routinely receive referrals for ABUS exams, sometimes for women who have not yet had a mammogram or who do not have dense tissue. In these situations we find ourselves explaining why they don’t need an ABUS study if their mammogram does not show dense breast tissue.

Patient results letters from my office include density information and any woman with a BIRADS density rating of 3 or 4 is informed that new research suggests they might benefit from an ABUS exam and to consult with their doctor. Women with benign findings and high density are flagged in physicians’ reports with the suggestion that an ABUS exam might provide clinical value.

All patient recall information is recorded in the practice database - for both mammography and ABUS. This ensures that the receptionist sees the ABUS component when scheduling the next year’s exam. This results in fewer “lost” exams and reduces the likelihood the women will need to return for a second appointment. 

Barrier: My Staff Does Not Want to Sell ABUS Exams

Technologists are one of the best resources to help patients understand how and why an ABUS exam might be appropriate for them. Some techs are initially resistant to talk to patients as they “don’t want to be sales people.” However, they quickly come around when they realize that what they’re really doing is helping find early cancers with ABUS.

We have all experienced the heartbreak of a regular screening patient returning with a lump that turns out to be an interval cancer. My technologists understand that informing patients about breast density and the option of additional screening with ABUS can help stop that from happening. They are very comfortable showing patients the difference between fatty breasts and dense breasts, and explaining to them what their density is.

Healthcare is moving closer and closer to personalized medicine as opposed to a one-size-fits-all approach. Mammography remains an important breast cancer screening tool, effective for all women in the appropriate age range. However, for at least 40 percent of women who have dense breast tissue, it should be viewed as a gateway or entry point to the screening process. For these women, it is not appropriate to stop at mammography as dense breast tissue may be hiding a cancer that we can find on ABUS.

Judy Dean, MD, is a diagnostic radiologist with more than 20 years of experience in women’s imaging.  She completed an ultrasound and body imaging fellowship at Stanford University, and medical school and residency at Loma Linda University.