エラストグラフィーにより不必要な乳房生検が減少する（Abstract# LL-BR4059-B04）

エラストグラフィーは超音波検査の特異度を改善し腫瘍のより詳細なマッピングを可能にする
Elastography improves ultrasound specificity and enables more precise mapping of tumors
エラストグラフィーは乳房超音波検査に追加すると有効で便利な技術であり、良性腫瘍とがん性病変を鑑別するのに役立つとの現在進行中のスタディ結果が2009年Radiological Society of North America (RSNA)学会で発表された。エラストグラフィーは従来の超音波画像を用いて圧縮率および病変の機械的属性を測定し超音波の特異度を改善する。悪性腫瘍は周囲の健常組織または嚢胞と比較し硬い傾向にあるため、エラストグラフィーで計測した圧縮率が高い病変は悪性でない可能性が高い。現在進行中のスタディの一部として、179人の患者（18～92歳、平均年齢55.1歳）に乳房の超音波検査およびエラストグラフィーを施行した。研究チームは184のエラストグラムを得て、硬い病変全てを生検した。134の生検のうち56が、がんであった。エラストグラフィーは生検でがんと診断された病変の98%、および良性であると診断された病変の82%を正しく同定した。エラストグラフィーは病変のサイズ計測の点でも超音波よりも正確であった。超音波検査は実際の腫瘍塊だけを見ており腫瘍塊が引き起こす周囲の変化は見ていないため腫瘍サイズを過小評価しうることに、筆者らは注意を促している。
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Elastography is an effective, convenient technique that, when added to breast ultrasound, helps distinguish cancerous breast lesions from benign results, according to an ongoing study presented today at the annual meeting of the Radiological Society of North America (RSNA).

When mammography yields suspicious findings, physicians often use ultrasound to obtain additional information. However, ultrasound has the potential to result in more biopsies because of its relatively low specificity, or inability to accurately distinguish cancerous lesions from benign ones. Approximately 80 percent of breast lesions biopsied turn out to be benign, according to the American Cancer Society.

"There's a lot of room to improve specificity with ultrasound, and elastography can help us do that," said the study's lead author, Stamatia V. Destounis, M.D., a diagnostic radiologist at Elizabeth Wende Breast Care, a large, community based breast imaging center in Rochester, NY. "It's an easy way to eliminate needle biopsy for something that's probably benign.

Elastography improves ultrasound's specificity by utilizing conventional ultrasound imaging to measure the compressibility and mechanical properties of a lesion. Since cancerous tumors tend to be stiffer than surrounding healthy tissue or cysts, a more compressible lesion on elastography is less likely to be malignant.

"You can perform elastography at the same time as handheld ultrasound and view the images on a split screen, with the two-dimensional ultrasound image on the left and the elastography image on the right," Dr. Destounis said.

As part of the ongoing study, 179 patients underwent breast ultrasound and elastography. The research team obtained 184 elastograms and performed biopsies on all solid lesions. Of 134 biopsies, 56 revealed cancer. Elastography properly identified 98 percent of lesions that had malignant findings on biopsy, and 82 percent of lesions that turned out to be benign. Elastography was also more accurate than ultrasound in gauging the size of the lesions.

"Ultrasound can underestimate the true size of lesions, as it only sees the actual mass and not the surrounding changes the mass may cause," Dr. Destounis said.

Coauthors are Andrea L. Arieno, B.S., Melissa N. Skolny, M.S., Renee Morgan, R.T., Patricia Somerville, M.D., and Philip F. Murphy, M.D.