Experience with Tomosynthesis (3-D) Mammography in a Mobile Setting and Current Controversies

Transcription

1 Experience with Tomosynthesis (3-D) Mammography in a Mobile Setting and Current Controversies Jennifer Lance, MHSA, MS Jerry McLarty, PhD LSU Feist-Weiller Cancer Center Shreveport LA Sept 15, 2008

2 A brief History of Mammography 1910 First crude x-ray pictures of breasts 1960 Vast improvement of film resolution 1970 First machines made exclusively for x-ray of the breast 2000 FDA Approval of Digital Mammography (DM), a spin-off of NASA Technology, the Hubble Telescope FDA Approved Tomosynthesis Mammography (TM) screening.

3 How Does Tomosynthesis work? X-ray Tube rotates- Multiple small dose images taken

4 Comparison of images, same breast A. 2-D (DM) B. 3-D (TM) 1mm slice

5 Why get TM? It is believed that TM provides: Clearer images of abnormalities within dense breast tissue Greater accuracy in pinpointing the size shape and location of breast abnormalities Fewer call-backs for diagnostic work-up or additional views Detects more cancers with fewer false positives Earlier detection of small breast cancers that may be hidden on a conventional digital mammogram (DM)

6 Tomosynthesis Mammography (TM) on a MOBILE UNIT has special needs compared to Digital Mammography (DM): Extra space for the mammogram suite A bigger weight-bearing vehicle More electrical power and cleaner power, an environmental control unit Special Training for mammography techs and radiologists A special 3-D reading station

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8 Dual axles to carry the weight

9 Mobile TM Needs: more communications bandwidth Tomosynthesis images can be huge ( 1 GB) We have a cellular router with 4 bonded channels (combined bandwidth of all 4 units) Typically, it takes minutes to transmit a set of images for a patient to the PACS system at the Health Sciences Center. Newer units can have up to 12 cellular channels, more than adequate bandwidth for sending TM.

10 Our Experience: Partners in Wellness Program In 1999 Our free Cancer Screening Program started in a Hospital Clinic In 2009 We added Mobile: We bought a used film mammography mobile unit and converted it to a Digital (2-D) machine In 2011 We ordered our 3-D unit, the first in the state. It was to be placed on a new mobile unit. In 2012 the FDA approved the use of the 3-D unit for mammography screening.

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13 Our TM Experience Nearly 3,000 patients a year are receiving screening mammography that detects cancers up to fifteen months earlier than 2-D mammography would reveal. American Medical School Association. ~ Fewer Call-back ~ ~ Decrease in False Positives ~ ~ Rural Area Call-Backs ~

14 Fewer Call backs 2 D D Van 18% 15% 12% Clinic 11% 10% 8% Van 6% 5% 4% Clinic 4% 2% 2% 16% 14% 12% 10% 15% 2D/3D Comparison Average over 3 years 8% 6% 4% 2% 0% 2D 10% 5% 3D 3% Van Clinic

15 False Positives 2D 3D Van / Clinic 32%* 10%* *follow-ups were unnecessary

16 True Call Backs ~ Un-needed Worry ~ ~ Resources ~ ~ Barriers ~ ~ Radiation ~

17 Call Backs Longer Travel Time = Lower Compliance Poor access to health care Longer waiting Financial pressures facing many facilities

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19 Controversies about TM The major studies demonstrating the benefits of mammography screening were performed before the advent of modern technology, DM and TM There have been no large randomized comparison of TM vs DM Most studies that have been done have been performed with only one manufacturer s products (Hologic). Only recently have GE and Siemens produced TM units. As with many screening technologies, the possibility of over-diagnosis* and over-treatment must be considered. No large, long-term, randomized clinical trials have be done of breast cancer screening with TM vs DM. * Discovery of small, slow growing tumors that may have never been otherwise detected in a patient s lifetime. But if found early by TM could lead to needless anxiety, further testing, even biopsy and surgery.

20 Tomosynthesis Mammographic Imaging Screening Trial (TMIST) 160,000 Women age year mammography screening, followed for 4.5 to 8 years depending upon time since enrollment Scheduled for annual or biennial screening, depending upon age, menopausal status, breast density, high-risk factors Randomized to either TM or DM > 100 screening sites in US and Canada

21 Enrollment success varies between sites Women who have experienced TM don t want to change Especially for sites that have been using TM for several years (this is our experience) Many women don t want to make such a long term commitment Health literacy is an issue, the study is complicated and the informed consent process can be daunting to some. There is no financial or other direct incentive to participate Some patients insurance does not pay for the additional cost for TM

22 The Bottom Line: Tomosynthesis is a powerful new development in mammography In our experience: Fewer call-backs Fewer false positives Helps detect breast cancer at an earlier stage Works well in a mobile setting Is over-diagnosis a problem? To be determined!