MRI can detect breast cancer
with a sensitivity approaching 100 percent, but it is not recommended for routine
screening because it has a specificity of only 37 to 97 percent. A lack of standardization
of imaging protocols may account for this, according to Dr. Paul D. Friedman (now
at Morristown Memorial Hospital in New Jersey) and his former colleagues at St.
Barnabas Medical Center in Livingston, N.J. In a review of breast MRI, the authors
said that bilateral imaging should be the standard technique.
The researchers use the sensitivity-encoding
parallel imaging technique combined with sequences such as turbo-spin echo and turbo-field
echo to produce high-resolution images with short acquisition times. They have achieved speeds of 47 seconds per time point and spatial resolution between 1.2 and 1.4 mm2 in plane and 1.5 mm through plane. They noted that parallel
imaging reduces motion and fold-over artifacts.
They said that bilateral imaging decreases the
risk of misdiagnosis because it provides a more symmetric image, making interpretation
easier. In addition, simultaneously imaging both breasts improves detection in patients
who already have been diagnosed with cancer because lumps may appear larger or smaller
at different times because of hormonal fluctuations. Bilateral imaging also eliminates
interobserver variability because unilateral images may be interpreted by two radiologists.
More accurate diagnoses improve patient
outcomes and reduce doctor liability. Furthermore, the researchers observed, doctors
and patients prefer to have images of both breasts before making decisions, so bilateral
imaging decreases the need for invasive procedures and follow-ups. (American
Journal of Roentgenology, Aug. 1, 2006, pp. 345-349.)
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