CHICAGO – A new diagnostic tool that can identify whether the blood flow around a tumor is characteristic of a benign or malignant lesion showed improved specificity when compared with standard devices, researchers reported here.
Among 1,739 patients who had 1,808 masses, specificity using the opto-acoustic device – a coupling of laser and ultrasound technology – was 43% compared with 28.1% for gray-scale ultrasound (P<0.0001), said Erin Neuschler, MD, of Feinberg School of Medicine at Northwestern University, Chicago
In the intention-to-diagnose analysis, the specificity was an absolute 14.9% greater with the opto-acoustic ultrasound generated images, Neuschler said in her oral presentation at the annual scientific sessions of the Radiological Society of North America.
The researchers used the devices to determine the need for biopsy lesions that were classified as BI-RADS 3 (Breast Imaging Reporting and Data) – an intermediate score that is most troublesome for clinicians.
Sensitivity of the gray-scale ultrasound was 98.6% compared with 96% for opto-acoustic ultrasound, meeting the pre-specified non-inferiority boundary of 5% (P<0.01), Neuschler reported.
“These data demonstrate that opto-acoustic ultrasound improved diagnostic specificity compared with ultrasound, resulting in reclassification of both benign and malignant lesions,” she said in discussing the so-called PIONEER study.
“The ability to downgrade the BI-RADS assessment of some benign masses may lead to fewer false positive examinations, short-term interval follow-up studies, and benign biopsies, potentially improving the accuracy of the diagnostic work-up and reducing some of the limitations and perceived harms of breast imaging,” Neuschler told MedPage Today.
Seven independent readers who were unaware of the clinical and biopsy information conducted 12,283 mass reads of the scans. In the trial 678 masses were malignant, 889 were benign, and another 190 were benign with a 12-month follow-up.
“Subgroup analyses showed no significant differences in specificity for either opto-acoustic ultrasound or gray scale ultrasound based on breast density, mass size, palpability, distance from nipple and depth,” she reported.
Neuschler explained that opto-acoustic ultrasound represents the fusion of anatomic and functional modalities, showing the amount of hemoglobin in and around breast masses, the level of oxygenization versus deoxygenization of hemoglobin, and the morphology of tumor blood vessels. “Cancers are generally more metabolically active and deoxygenate hemoglobin more than benign entities of normal tissue,” she said.
Clinicians used a hand-held linear probe that can perform gray-scale ultrasound and also emit optical pulses from a Grade 3b laser, allowing generation of opto-acoustic images. Color-coded opto-acoustic data was temporally interleaved and co-registered with the gray-scale ultrasound image in real time.
“The opto-acoustic ultrasound findings may help identify masses that do not require biopsy, and in some cases, avoid short interval follow-up,” Neuschler said. “Conversely, opto-acoustic ultrasound may increase suspicion and add certainty to the need for biopsy of malignant masses.”
“I am pretty impressed with this device,” said session moderator Udo Hoffman, MD, of Massachusetts General Hospital and Harvard Medical School, Boston.
“It seems like a biologically sensible hypothesis that blood oxygenation could reveal something about the malignancy or benign nature of the tumor. On the face of it, this technology does make sense, ” he told MedPage Today. He was not bothered by the relatively low specificity, noting the exclusion of “clearly benign or clearly malignant” lesions in the analysis.
The study was supported by Seno Medical Instruments, San Antonio.
Neuschler disclosed relevant relationships with Seno Medical Instruments, Northwest Imaging Forums, ABC Medical Education, and General Electric Company.
Hoffmann has disclosed relevant relationships with Bracco Diagnostics, Genentech, and Siemens Healthcare.