Ultrasound-guided optical tomography may reduce unnecessary breast biopsies
MedWire News: Ultrasound-guided diffuse optical tomography provides additional tumor angiogenesis information that allows physicians to differentiate early-stage breast cancers from benign lesions, study findings indicate.
Diffuse optical tomography is a non-invasive imaging technique that measures light absorption within tissue to quantify tumor hemoglobin content, which is directly related to tumor angiogenesis and tumor hypoxia, explain Quing Zhu (University of Connecticut, Storrs, USA) and colleagues.
Because cancerous lesions have many more blood vessels than normal tissue, hemoglobin levels can help distinguish malignant from benign lesions.
To investigate the potential role of ultrasound-guided diffuse optical tomography in the near-infrared spectrum as a means of differentiating early-stage breast cancers from benign lesions, Zhu and team studied 178 consecutive women (aged 21–89 years) referred for ultrasound-guided biopsy.
After locating the lesion, diffuse optical tomography was performed and light absorption was measured at 780 and 830 nm. From this measurement, the researchers calculated total hemoglobin (tHb) concentration as a marker of tumor angiogenesis, and correlated their findings with core biopsy results.
Biopsy results revealed two in situ carcinomas (Tis), 35 T1 carcinomas, 24 T2–T4 carcinomas, and 114 benign lesions among the cohort. Both maximum and mean tHb levels were significantly higher in the malignant group than in the benign group, report the researchers in the journal Radiology.
For Tis–T1 tumors, the maximum and mean tHb levels were 102.0 mmol/l and 71.9 mmol/l, respectively. For T2–T4 tumors they were 100.3 mmol/l and 67.0 mmol/l, respectively.
Maximum and mean tHb levels in the benign group were approximately half those of the malignant groups at 55.1 mmol/l and 39.1 mmol/l, respectively.
When 82 mmol/l was chosen as a threshold level to distinguish between malignant and benign lesions, the sensitivity, specificity, positive predictive value, and negative predictive values for Tis–T1 cancers were 92%, 93%, 81%, and 97%, respectively. The corresponding values for T2–T4 tumors were 75%, 93%, 69%, and 95%.
"Based on our results, we believe that ultrasound-guided diffuse optical tomography holds promise as an adjunct to diagnostic mammography and ultrasound for distinguishing early-stage invasive breast cancers from benign lesions," Dr. Zhu said.
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By Laura Dean