Breast sonography is one of the most widely prescribed ultrasound procedures. Currently, ultrahigh frequency probes are available with exquisite dot size, superb axial and lateral resolution, and extended dynamic ranges reaching over 100 dB. The GE 12MHz transducer is a superb example of this technology.

The wide acceptance of ultrasound as a diagnostic modality has been documented extensively. Volumes of literature have been published on the monographic appearance of cyst-versus-solid and benign-versus- malignant (Ref. 1 and 2). Employment of high-frequency probes has made evaluation of the lesion capsule and the internal architecture a standard practice.

Sonography of the breast, like many other aspects of ultrasound, remains a technically challenging procedure. Great care must be taken to assure an accurate diagnosis

Varying degrees of probe pressure over a suspected lesion can dramatically affect diagnosis. Unlike sonography of deep anatomical structures, probe pressure is critical in the evaluation of superficial anatomy. The degree of probe pressure applied can cause anatomy to change shape, location, affect acoustic impedance or change the appearance of blood flow.

Light probe pressure applied over a suspected breast lesion may result in artifactual shadowing. Shadowing distal to a solid breast lesion is one of the nine criteria developed by Stavros, et.al. (Ref. 3) indicating malignancy (Fig.1a). Graduated pressure flattens the tissue and the posterior shadowing is diminished or completely disappears, reducing suspicion for malignancy (Fig.1b).

Use of Doppler to characterize blood flow in breast lesions has been documented (Ref 4,5,6). Little has been published documenting the ramifications of improper probe pressure. Applying improper pressure may completely obliterate the vascularity and give the impression of an avascular lesion (Fig.2). Varying probe pressure when employing Doppler may diminish this phenomena.

Fig. 1a	Fig. 1b

Fig. 1a is an image of a breast lesion. Because shadowing was encountered, malignancy is suspected. Increasing probe pressure properly flattened the tissue and acoustic shadowing dramatically dissipated, reducing the suspicion for malignancy Fig. 1b.

Fig. 2

Fig. 2 is a split screen image of a breast lesion employing power Doppler. The image on the left side is with proper probe pressure and lesion flow is observed. The image on the right is with increased probe pressure and vascularity is completely lost.

• GE 12MHz transducer

The previous examples dramatize the need to understand the effects probe pressure can have on diagnosis and modality employed. Graduated pressure over a breast lesion may diminish or remove shadowing, thus lowering suspicion for malignancy. However, applying the same pressure over a lesion when employing Doppler may obliterate flow entirely, again affecting diagnosis. Therefore, varying degrees of probe pressure are necessary for an accurate diagnosis. Further investigation is necessary to explore the implications of probe pressure and its effect on diagnosis.

• Heywang SH, Lipsit ER, Glassman LM, et al., Specficity of ultrasonography in the diagnosis of benign breast masses. J Utrasound AIFD 1984;3:453-461.

• Calderon C., Vikomerson, D., Mezrich R., et al. Differences in attenuation for ultrasound by normal, benign, and malignant breast tissue. J Clin Utrasound 1976;4:249-254.

• Stavros, AT, Dennis M, chptr. 11 Percutaneous Breast Biopsy, edited by Steve Parker and William Jobe, Raven Press, Ltd., New York © 1993.

• Wells, PNT, Halliwell M, Skidmore R, et al. Tumur detection by ultrasonic Doppler blood-flow signals. Ultrasonics 1977; 15:231-232.

• White DN, Cledgett, PR, Breast Carcinoma detection by ultrasonic Doppler signals. Ultrasound Med Biol 1978;4:329-335.

• Burns PN, Halliwell M, Wells PNT, Webb AJ Ultrasonic Doppler studies of the breast. Ultrasound Med Biol 1982;8:127-143.

Print copies of these clinical papers are available from GE. Many of the figures are easier to read on the print copies than they are here. To receive your own copy, send email to GE and reference publication number 96-4528.

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