New Breast Imaging Techniques Allow Tailoring of Therapy

NEW ORLEANS—The diagnosis of breast cancer is becoming less invasive and far more accurate, said Steve H. Parker, MD, director of the Sally Jobe Breast Centre, Denver. Dr. Parker delivered the plenary lecture at the American Society of Breast Disease annual meeting, cosponsored by the Ochsner Medical Foundation.

Advances in Ultrasound

New ultrasonography technology has had a dramatic impact on breast imaging in the last 5 years. “In fact, you should be wary of any radiologist using equipment that is older than this,” Dr. Parker said, noting that such technology is already largely out of date.

New breast-specific software and very-high-frequency, broad-band-width transducers have allowed for excellent resolution of very small structures within the breast and the detection of subcentimeter cancers. This technology can differentiate between solid lesions that should be biopsied and those that can be followed. “The dictum ‘biopsy all that’s solid’ is an outdated concept,” he said, “but you have to have the best equipment and experienced radiologists.”

Microcalcifications that require biopsy should generally be approached with stereotactic mammographic guidance. Most stereotactic units now have digital imaging that provides superior contrast resolution and near-instantaneous image display, compared with film-screen imaging. “These units are ideal for specimen radiography as well as ductography and the workup of microcalcifications,” he commented.

Several manufacturers now offer full-field digital mammography that promises to provide superior contrast resolution, increased throughput, and reduced radiation exposure, compared with standard film screening mammography. However, these devices are not yet FDA approved and are still quite expensive, Dr. Parker said.

Breast MRI

Breast MRI (dynamic or high-resolution), while also expensive, has been approved by the FDA. “We have found it to be an exceptionally helpful tool in treatment planning,” Dr. Parker said. Both types of breast MRI utilize gadolinium contrast injection. Dynamic breast MRI images the breast in the first 90 seconds after injection, which gives poor spatial resolution and sensitivity but offers improved specificity, compared with high-resolution breast MRI.

High-resolution RODEO (ROtating Delivery of Excitation Off-resonance] MRI offers very high sensitivity with spectacular spatial resolution but poorer specificity. With RODEO, a follow-up ultrasound is recommended to determine the need for biopsy, he noted.

“RODEO MRI is most useful in the preoperative assessment of a patient who has a dense mammogram and a biopsy-proven infiltrating lobular carcinoma in situ (LCIS) (see Figure 1), ductal carcinoma in situ (DCIS), or infiltrating duct carcinoma with DCIS,” he said. “In these instances, the true extent of disease is much better appreciated than with standard mammographic images, and the surgery can be appropriately tailored.”

Dr. Parker stressed that “we are not using breast MRI to determine benign vs malignant disease, but to look at cancer and see how best to treat it. The 3D image shows you the areas of enhancement. We have been inundated by requests for breast MRI from surgeons and oncolgists. In fact, our outpatient scanner is becoming almost totally a breast MR scanner. That’s how many we are doing.”

In concert with the improvements in imaging, there have been marked improvements in tissue acquisition as well. The Mammotome (directional vacuum-assisted biopsy using a thin rotating blade), which was introduced in 1995 and which Dr. Parker helped develop, allows a greater amount of tissue to be harvested in a much shorter time (see Figure 2 ). In addition, the tissue is obtained contiguously, leaving no region of the biopsied area unsampled.

The Mammotome, which is used with ultrasound guidance, has solved the problem of underestimation of disease by standard automated core biopsy, he said. “There is nothing left unsampled,” he noted. “It’s an unequivocal biopsy.”

Dr. Parker uses an 11-gauge Mammotome needle for stereotactic biopsy, primarily for calcifications but also for small breast masses, and a 14-gauge needle for core biopsy of lesions greater than 1.5 cm.

The success of these new instruments in removing entire malignancies has opened the possibility of actually using image-guided diagnostic biopsy in place of standard surgical lumpectomy, he pointed out. However, thus far it has been difficult to predict the margin status with these devices.

Other investigators are pursuing the possibility of in situ ablation with stereotactic or MRI-guided laser therapy and ultrasound-guided cryotherapy. It is likely that some form of percutaneous lesion removal, perhaps combined with sentinel node biopsy or in situ ablation, may be forthcoming, he said.

“I am convinced that there will come a time when the removal of small cancers will require only a small hole over the lesion and one over the axilla. You won’t be able to tell the surgeon has been there,” Dr. Parker predicted.