Breast lesions: imaging with contrast-enhanced subharmonic US--initial experience.
OBJECTIVE
To prospectively compare accuracy of gray-scale subharmonic imaging (SHI) with that of standard gray-scale ultrasonography (US), power Doppler US (with and without contrast material), and mammography for the diagnosis of breast cancer, with histopathologic or clinical follow-up results as the reference standard.


METHODS
This HIPAA-compliant pilot study had institutional review board approval; all subjects gave written informed consent. Fourteen women (age range, 37-66 years) had 16 biopsy-proved breast lesions. In SHI, pulses are transmitted at one frequency, but only echoes at half that frequency (the subharmonic) are received. A US scanner was modified to perform gray-scale SHI (transmitting at 4.4 and receiving at 2.2 MHz). Precontrast imaging (gray-scale US and power Doppler) was followed by contrast material-enhanced power Doppler and gray-scale SHI. A reader blinded to mammographic and pathologic findings assessed diagnosis on a six-point scale. Sensitivity, specificity, accuracy, and receiver operating characteristic (ROC) curves were computed for mammography, gray-scale and power Doppler imaging (pre- and postcontrast), and SHI.


RESULTS
Of the 16 lesions, four (25%) were malignant. Mammography had 100% sensitivity and 20% specificity. Sensitivity and specificity, respectively, were 50% and 92% for precontrast imaging and 75% and 75% for contrast-enhanced power Doppler. SHI had 75% sensitivity and 83% specificity. Specificity was higher for all US modes than for mammography (P<.04). There were no significant differences in specificity among US modes or in sensitivity (P>or=.50). Area under the ROC curve for the diagnosis of breast cancer was 0.64 for standard gray-scale US and power Doppler US, 0.67 for contrast-enhanced power Doppler US, 0.76 for mammography, and 0.78 for SHI (P>.20). Contrast enhancement was better with SHI than with power Doppler (100% vs 44% of lesions with good or excellent enhancement; P=.004).


CONCLUSIONS
SHI appears to improve the diagnosis of breast cancer relative to conventional US and mammography, albeit on the basis of results in a very limited number of subjects.
Forsberg
Flemming
F
Department of Radiology, Thomas Jefferson University, Suite 763J, Main Building, 132 S 10th St, Philadelphia, PA 19107, and GE Healthcare, Milwaukee, WI, USA. flemming.forsberg@jefferson.edu
Piccoli
Catherine W
CW
Merton
Daniel A
DA
Palazzo
Juan J
JJ
Hall
Anne L
AL
D000328:Adult; D000368:Aged; D000418:Albumins; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D016009:Chi-Square Distribution; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D005466:Fluorocarbons; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler / Q000379:methods*; D016217:Ultrasonography, Mammary / Q000379:methods*
D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons