3D超音波有助於乳房病灶分類


  【24drs.com】根據發表於2012年歐洲放射科研討會(ECR)的研究,多模組斷層(MUT)是一種新的立體(3D)影像科技,可有效偵測並分類小到2 mm大小的乳房病灶。
  
  這個獨特的影像方法是在ECR 2011首次發表,使用傳輸型超音波、對水浴槽中的乳房進行3D掃描,建構每個冠狀切片的多重影像。
  
  南加大洛杉磯分校生物醫學工程教授Vasilis Marmarelis博士表示,這個技術在許多方面提供了比乳房攝影更關鍵的優勢,包括減少放射線曝露與不適。
  
  發明此技術的Marmarelis博士解釋,對技術員而言,MUT技術更簡單,對病患而言則是更舒適,且不會有X光乳房攝影的離子放射線。
  
  進行中的臨床試驗包括的病患數是2011年的2倍之多,比較103名婦女的MUT影像和 「Breast Imaging Reporting and Data System (BI-RADS)」影像,病灶分4類,也包括了疑似病灶的微創侵犯式核心切片的組織病理學檢查。
  
  病灶大小範圍介於2.0-28.0 mm,平均大小為7.1 mm。研究結果認為,MUT可以偵測且準確分類切片樣本34個惡性病灶中的33個,敏感度為97.1%。
  
  針測的33個惡性病灶中,15個(45%)的最大直徑為5 mm以下,主要是原發性乳管原位癌(DCIS),偵測到直徑最小的是2 mm的惡性病灶(都是DCIS)。
  
  MUT的偽陽性結果有1例(專一性為98.5%)。
  
  Marmarelis醫師表示,我們這篇進行中的試驗發現證明了我們MUT技術的關鍵能力:偵測到位於緻密乳房中、2 mm這麼小的惡性病灶。
  
  他解釋,這項技術檢查單側乳房需時12分鐘左右,唯一結合超音波和斷層讀數而更佳地偵測病灶。
  
  MUT技術優於現有模式的關鍵能力是,區別病灶和正常乳房組織、區別惡性和良性病灶的能力,在組織-立體像素層次適當使用多元聲波特性;使用MUT和超音波傳輸斷層攝影(一種有別於現有的回音式超音波的方法)測量這些特性,它們代表著對細胞顯微構造之體聲波學性質的新穎且嚴謹的校正方式。
  
  因為惡性和良性病灶、正常乳房組織之間的細胞顯微構造顯著不同,適當結合這些測量特性,可以透過電腦分類分辨各病灶。
  
  紐約羅徹斯特Elizabeth Wende乳房照護中心管理合夥人Stamatia Destounis醫師表示,使用水浴技術進行超音波並不是新發明,但是,可能會讓某些病患感到尷尬。
  
  美國放射科學院研究員Destounis醫師表示,我們從1980年代開始使用水浴技術,當時是為了試著釐清如何使用超音波掃瞄病患影像,因此,這次的技術是有趣的。
  
  Marmarelis醫師指出,MUT技術的一個運用限制是,無法掃描靠近胸壁(胸肌)的乳房組織,以及腋下附近腋窩區域的副乳,因為這方法僅能掃描水浴中的乳房部分。
  
  他相信未來這個問題可以藉由改變設計而克服,但Destounis醫師表示,這是超音波的共同議題。她解釋,所有水浴超音波的限制都是,乳房是下垂的,特別是大胸部的女性,可能無法如你所願地穿透,乳房的遠端內側或下方、或者乳房的所有邊緣都會是限制。
  
  Destounis醫師也提出疑問,一旦偵測到病灶,如何進行乳房切片。目前的研究中,使用別的方式進行病灶切片;令人好奇的是,是怎樣進行切片。
  
  Marmarelis醫師回應表示,切片過程目前是遵守「已經建立的標準臨床步驟」。換句話說,我們的MUT結果並不會改變根據已經證實的研究規範所提的現有切片步驟,不過,一旦MUT成為可信賴的篩檢、偵測與定位技術,將可更有助於協助切片,因其具有3D固定座標系統。
  
  資料來源:http://www.24drs.com/professional/list/content.asp?x_idno=6746&x_classno=0&x_chkdelpoint=Y
  

3D Ultrasound Effective for Breast Lesion Classification

By Nancy A. Melville
Medscape Medical News

March 2, 2012 (Vienna, Austria) — Multimodal tomography (MUT), a novel 3-dimensional (3D) imaging technology, is effective in detecting and classifying breast lesions as small as 2 mm in size, according to research presented here European Congress of Radiology (ECR) 2012.

The unique imaging method, first introduced at ECR 2011, uses transmission ultrasound to perform a 3D scan of a pendulant breast in a water bath, and reconstructs multiple images for each coronal slice.

The technology offers several key advantages over mammography in terms of reduced radiation exposure and discomfort, said coauthor Vasilis Marmarelis, PhD, who is professor of biomedical engineering at the University of Southern California, Los Angeles.

"The MUT technology is much simpler for the technician, far more comfortable for the patient, and without the ionizing radiation of x-ray mammography," explained Dr. Marmarelis, who invented the technology.

The ongoing clinical trials involve about twice as many patients as reported in 2011, compare MUT imaging in 103 women with Breast Imaging Reporting and Data System (BI-RADS) category 4 lesions, and involve histopathology from minimally invasive core biopsy of the suspicious lesions.

The lesions ranged in size from 2.0 to 28.0 mm, with an average size of 7.1 mm.

The results indicated that MUT was able to detect and accurately classify 33 of 34 malignant lesions in the biopsy samples, for a sensitivity of 97.1%.

Fifteen of the 33 (45%) detected malignant lesions had maximum dimensions of 5 mm or less, and were primarily ductal carcinoma in situ (DCIS). The smallest detected malignant lesions (all DCIS) were 2 mm in size.

There was 1 false-positive result (98.5% specificity) with MUT.

"The findings of our ongoing trials...corroborate a key capability of our MUT technology to detect reliably malignant lesions down to 2 mm..., even in a dense breast," Dr. Marmarelis told Medscape Medical News.

The technology, which takes about 12 minutes per breast, uniquely combines ultrasound and tomography readings to better detect lesions, he explained.

"The key capability of the MUT technology that sets it apart from existing modalities is its demonstrated ability to differentiate lesions from normal breast tissue, as well as malignant from benign lesions, using proper combinations of multiple acoustic attributes at the tissue-voxel level."

"These attributes are measured by MUT with ultrasound transmission tomography — an approach fundamentally different from the current echo-mode clinical ultrasound — and they represent novel and rigorous calibrated measures of the bulk acoustic properties of cellular microstructure."

"Since the cellular microstructure of malignant and benign lesions, as well as normal breast tissue, is distinctly different, these measured attributes, properly combined, can differentiate the lesions through computational classification clustering."

The use of a water-bath technique for ultrasound is not new, but might appear foreign and somewhat awkward to some patients, said Stamatia Destounis, MD, a managing partner at Elizabeth Wende Breast Care in Rochester, New York.

"We used to do the water-bath technique the 1980s when we first were trying to figure out how to image patients with ultrasound, so this is interesting," said Dr. Destounis, who is a fellow with the American College of Radiology.

Dr. Marmarelis noted that one practical limitation of the MUT technology is the inability to scan breast tissue near the chest wall (pectoral muscle) and in the axillary region of the breast extension near the armpit because of the way the breast is positioned for scanning in the water bath.

He added that he is confident the problem can be overcome in the future with design changes, but Dr. Destounis said the issue is common with ultrasound.

"That's a limitation with all ultrasound in a water bath in which the breast is pendulous," she explained "Particularly with large-breasted women, you may not be able to penetrate as well as you would like. The far medial or inferior, or I would think all the edges of the breasts, would be limitations."

Dr. Destounis also questioned how the breast would be biopsied with the technique once a lesion is detected. "In the current study, the lesions were biopsied with another method; I'm curious about how the biopsy would work in this kind of situation."

Dr. Marmarelis responded that the biopsy process currently follows the "established standard clinical procedure."

"In other words, our MUT results are not allowed to alter the established biopsy procedure yet, according to the approved study protocol. However, I expect that as soon as MUT becomes accepted as a reliable screening, detection, and localization technology, it will also become extremely useful in assisting biopsies because of its 3D fixed-coordinate system."

Dr. Marmarelis reports being the inventor and developer of MUT, and a cofounder and shareholder of the start-up company MastoScopia S.A., which is performing the initial clinical validation trials in the European Union. Dr. Destounis has disclosed no relevant financial relationships.

European Congress of Radiology (ECR) 2012: Abstract B-0218. Presented March 1, 2012.

    
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