No screening test can aid in the early identification of ovarian cancer, which is the deadliest malignancy of the female reproductive system. Some individuals have their ovaries removed prematurely because ultrasound imaging, the standard of treatment for determining whether tumors are benign or malignant, is not always reliable.
Researchers and medical personnel at Washington University in St. Louis have discovered a way to combine functional biomarkers with photoacoustic imaging, a method that uses near-infrared light at particular wavelengths that are absorbed differently by oxygenated and deoxygenated hemoglobin, to increase the standard of care diagnostic accuracy of potentially cancerous lesions in the ovaries and adnexal regions or the fallopian tubes.
According to the results of this new supplementary evaluation technology, some patients might be able to avoid having irregularly looking lesions surgically removed, which would save medical expenses and perhaps minimize procedure-related consequences.
Quing Zhu, the Edwin H. Murty Professor of Engineering at the McKelvey School of Engineering, collaborated with a group of medical professionals from the Washington University School of Medicine. The team was led by Matthew Powell, MD, who is the director of the Division of Gynecologic Oncology and teaches obstetrics and gynecology; and Cary Siegel, MD, who is a professor of radiology and heads the gastrointestinal/genitourinary fluoroscopy section at the Mallinckrodt Institute of Radiology.
The goal was to incorporate photoacoustic imaging into the routine care of women who are scheduled to undergo surgery to remove adnexal lesions and/or ovaries due to possible malignancy.
The researchers noted that although photoacoustic imaging has been used to help diagnose a variety of distinct cancers, such as those of the breast, skin, colorectal, and other female reproductive system tumors, it has not been used to categorize the risk of adnexal malignancy.
Their study’s conclusions were released in Ultrasound in Obstetrics and Gynecology’s December 2023 edition.
Photoacoustic imaging combined with ultrasound provides complementary diagnostic imaging data involving structure and function. The ultrasound localizes the lesion, and the photoacoustic images inform tumor hemoglobin content and percent of blood oxygen saturation.
Quing Zhu, Edwin H. Murty Professor of Engineering, McKelvey School of Engineering, Washington University in St. Louis
Blood oxygen saturation and hemoglobin concentration offer useful details on oxygen use and the vasculature inside the tissue. Malignant lesions can be distinguished from benign lesions by their greater hemoglobin content, which is caused by tumor angiogenesis, and their lower blood oxygen saturation, which is caused by increased tumor metabolism.
In a clinical investigation, 68 women set to have their ovaries surgically removed received clinical ultrasonography as well as Zhu’s team’s created combined photoacoustic and ultrasound technology (PAT/US). There were 14 individuals with malignant tumors in their ovaries or adnexal areas, two with malignant fallopian tubes, and 52 with benign abnormalities.
Each lesion was rated by two radiologists using the Ovarian-Adnexal Reporting and Data System (O-RADS), which categorizes risk for malignancy into six categories, with O-RADS 0 indicating an incomplete evaluation and O-RADS 5 indicating a risk of malignancy more than 50%.
Women frequently develop ovarian cysts, which cause a great deal of worry. This technology should quickly and easily be able to help assure both the doctor and the patient that most of these can be watched, and unnecessary surgery can be avoided. These surgeries can lead to loss of fertility and early menopause. This technology and other imaging advancements could be immensely helpful to improve the lives of our patients.
Matthew Powell, MD, Director, Division of Gynecologic Oncology and Professor, Obstetrics and Gynecology, Washington University in St. Louis
When comparing malignant and benign lesions, individuals with malignant tumors in the ovaries and adnexal area had 1.8 times the relative total hemoglobin of those with benign lesions. The blood oxygen saturation was 5% lower in patients with malignant lesions, although the difference was not statistically significant.
The presence of the cancer antigen CA 125 was substantially different in patients with malignant lesions compared to individuals with three common forms of benign lesions, but not in patients with endometriosis, abscess, adhesions, infarction, or torsion.
Finally, the researchers discovered that relative total hemoglobin, the O-RADS score, the presence of the cancer antigen CA 125, and the percentage of blood oxygen saturation (sO2) were the most important predictors of malignancy.
Their model, which included all four characteristics, had an area under the receiving characteristic curve (AUC) of 0.97, a metric used in medical imaging diagnostics to assess the effectiveness of a model. A score of 1 shows that the model performed perfectly.
The assessment of the adnexal mass may be challenging for an experienced radiologist, as many different benign and malignant causes are often in the possibilities for diagnosis. Novel imaging techniques like photoacoustic ultrasound that increase the radiologist’s accuracy and confidence are critical to improving early diagnosis and treatment of ovarian cancer. With early diagnosis, our ultimate goal is to improve ovarian cancer survival. Working with Dr. Powell, Dr. Zhu and her engineering team has been a highlight of my medical career.
Cary L. Siegel, MD, Professor, Radiology, Washington University in St. Louis
The National Institutes of Health provided funding for this study (R01CA237664). This study is a midterm data analysis from a clinical trial that was authorized by an Institutional Review Board. The Radiology and OB/GYN clinical trial offices assisted with patient recruitment and consent, as well as regulatory oversight.
Zhu, Q., et. al. (2023) Characterization of adnexal lesions using photoacoustic imaging to improve sonographic O-RADS risk assessment. Ultrasound in Obstetrics and Gynecology. doi:10.1002/uog.27452