CHICAGO (EGMN) – An ultrasound technique that measures tissue elasticity could dramatically alter the way in which skin cancer is diagnosed.

In a prospective study of 56 patients with proliferative malignant neoplasms or benign skin lesions, the use of ultrasound elastography analysis prior to biopsy correctly differentiated benign from malignant lesions in 100% of cases (P value equal .0007), Dr. Eliot Siegel reported Dec. 1 at the annual meeting of the Radiological Society of North America.

“We believe that ultrasound has tremendous potential that is completely untapped now to characterize and delineate the extent of skin lesions currently evaluated visually,” he said.

“We believe it has tremendous promise to reduce unnecessary biopsies.”

Elastography noninvasively estimates the axial tissue strain, or elastic properties of tissue. Cystic lesions demonstrate high levels of elasticity, while malignant lesions are relative “hard” with a very low level of elasticity.

Ultrasound with elastography, more so than optical or light images, is unique in its ability to provide the proper depth at which to analyze lesions – around 5 mm below the surface, said Dr. Siegel, vice chair of radiology and a professor at the University of Maryland in Baltimore. This may be useful in the early detection of melanoma before the classic signs such as asymmetry or changes in border are present on the skin’s surface. In addition, elastography could have a role during surgery.

“This also could guide the surgeon as the surgeon is doing an excision or biopsy to not just look at the tip of the iceberg that they can see at the skin surface, but actually to be able to look deeper, so they can see exactly which areas they can cut out safely and still remove the entire tumor without unnecessarily removing more than that,” he said.

Elastography software is available on most new ultrasound machines, and has been used with promising results for breast, thyroid, and liver cancer. It has not been used to explore skin lesions, except for one prior study from 2007.

That study used absolute strain values, whereas Dr. Siegel and associates also calculated strain ratios. Malignant lesions had higher strain ratios (minimum 5.3; maximum 32.2), compared to benign lesions (min. 0.01; max. 3). None of the malignant lesions violated a strain-ratio cutoff of 3 to 5, Dr. Siegel said. He presented a few examples, including a squamous cell carcinoma with a ratio of 13.27 and a benign keloid with a ratio of 1.25.

Although preliminary, the data suggest that strain ratios may also be useful in distinguishing between malignant lesions. Squamous cell carcinomas had a higher ratio overall, said coauthor Dr. Bahar Dasgeb, a radiologist and second-year dermatology resident at Wayne State University in Detroit. Moreover, the strain ratio was higher, even within squamous cell or basal cell cancers, when more invasive cells were present.

If strain ratios are combined with higher ultrasound frequencies, it’s possible that the anatomic information gleaned from elastography “could rival the information that a pathologist would see after the lesion was excised,” Dr. Siegel said.

“That’s really the direction that we’d like to head into for research and development, as we look at much higher ultrasound frequencies.”

The current study used a clinically available 14-16 mHz ultrasound unit.

The findings were enthusiastically received when presented by Dr. Dasgeb at the Michigan Dermatological Society meeting in November.

“The feedback from Mohs’ surgeons was amazing,” she said in an interview. “A couple of clinical dermatologists said, ‘there is no other way.’ ”

She suggested transitioning this technology from radiology to clinical dermatology would not be difficult nor take long because of need and the rising incidence and economic impact of skin cancer.

Dr. Siegel disclosed receiving research grants from several imaging companies. Dr. Dasgeb had no disclosures.

Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

芝加哥(EGMN)——一种测定组织弹性的超声技术可显著改变皮肤癌的诊断方式。

 

Eliot Siegel博士在12月1日召开的北美放射学会(Radiological Society of North America)年会上报告，一项纳入56例增生性恶性肿瘤或良性皮肤病变患者的前瞻性研究显示，在活检前应用超声弹性成像检查可在所有患者中准确鉴别良性和恶性病变(P=0.0007)。

 

他说，“我们认为，在描述当前肉眼评估皮肤病变的程度方面，超声的巨大潜力尚未被完全开发。”

 

 “我们认为，超声可显著减少不必要的活检。”

 

弹性成像技术可非侵入性地评价轴向组织应变或组织弹性。囊性病变组织的弹性较高，而恶性病变组织相对较“硬”，弹性极低。

 

巴尔的摩马里兰大学教授兼放射科副主任Siegel博士表示，超声弹性成像比光学成像更独特，其独特性在于能够提供皮肤表面下约5 mm的图像，这是分析病变组织的合适深度。这有助于在皮肤表面出现典型体征(如不对称性或边缘改变)之前早期发现黑色素瘤。 此外，弹性成像可在手术期间应用。

 

他说，“这种技术还可在外科医生进行切除或活检时指导其不仅观察皮肤表面，而且还可观察到更深的部位，从而使其能够看清楚哪些是能够安全切除的区域，进而在不必要切除过多正常组织的情况下，切除全部肿瘤组织。”

 

弹性成像软件可应用于大多数新型超声机器，其检测乳腺癌、甲状腺癌和肝癌的效果较好。 弹性成像技术尚未被用于检测皮肤病变，除了此前2007年的一项研究。

 

该既往研究计算了绝对应变值，而Siegel 博士及其同事还计算了应变比。恶性病变组织的应变比(最小：5.3；最大：32.2)大于良性病变组织(最小：0.01；最大：3)。 Siegel博士说，没有恶性病变组织的应变比超出3~5的临界值。他举了几个例子，如鳞状细胞癌的应变比为13.27，良性瘢痕瘤的应变比为1.25。

 

尽管所获得的数据为初步数据，但这些数据表明，应变比也有助于鉴别恶性病变。底特律韦恩州立大学的放射科医生和皮肤科第二年住院医师Bahar Dasge博士表示，总体而言，鳞状细胞癌的应变比相对较高。 此外，当存在较多浸润细胞时，应变比更高，即使在鳞状细胞癌或基底细胞癌组织中。

 

Siegel博士表示，如果同时测定应变比并应用较高的超声频率，则从弹性成像检查获得的解剖学资料“可与病理医生在切除病变组织后观察到的资料相当。”

 

 “我们希望在应用更高的超声频率进行观察时，研究能够真正朝这一方向发展。”

 

当前这项研究应用的超声频率是临床上常用的14~16 mHz 。

 

在11月召开的密歇根皮肤病学会(Michigan Dermatological Society)会议上，Dasgeb博士所报告的结果引起了热烈反响。

 

她在接受采访时说，“来自Mohs外科医生的反馈较为强烈。一些临床皮肤病医生说，‘没有其他方法可与之相媲’。”

 

她表示，将该技术从放射领域延伸应用于临床皮肤病领域既不难，也不会花太多时间，因为存在这种需求，并且皮肤癌发生率及其带来的经济负担正与日俱增。

 

Siegel 博士披露，其接受来自数家成像公司的研究资金。Dasgeb博士声明，其无任何经济利益冲突。

 

 

鳞状细胞癌的弹性成像图像(左)和超声图像(右)对比。由于恶性病变组织比良性病变组织更硬，因此在高频超声成像基础上加用弹性成像检查皮肤，能够提高皮肤癌传统临床诊断的准确性，并且能够使一些良性皮肤病变病例避免不必要的活检。(图片由北美放射学会提供)

 

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