Subharmonic ultrasound scores over harmonic ultrasound for detecting contrast flow in breast masses: Study
USA: A recent study has reported 3D subharmonic ultrasound to be better for the detection of contrast flow in vascular breast masses compared to 3D harmonic ultrasound. Also, characterizing indeterminate breast lesions with quantitative 3D subharmonic imaging parameters and clinical assessments were shown to improve diagnostic accuracy.
The study findings were presented at the Radiological Society of North America (RSNA) 2021 annual meeting by Flemming Forsberg from Thomas Jefferson University in Philadelphia.
"If quantitative parameters are added together, the accuracy increases and end up in the 90% to 95% range," said Forsberg.
Harmonic imaging is available widely and previous research has shown its ability to provide better-quality images compared to conventional ultrasound. However, in a review published in the journal Ultrasonics in 2000, Forsberg said that harmonic imaging is related to problems due to second-harmonic generation and accumulation within the tissue itself. He suggested that subharmonic imaging, which works by imaging microbubble ultrasound contrast agents should have much better lateral resolution and may work well in scanning structures deep in the body.
For the study, Forsberg and the team aimed to assess the ability of contrast-enhanced nonlinear 3D harmonic and subharmonic imaging to characterize suspicious breast lesions using clinical assessments by radiologists and quantitative parameters.
For the study, the researchers included data from 219 women who were successfully scanned, including 55 malignant cases. All women went on to have a breast biopsy and pathology assessments were used as the reference standard. Five independent radiologists scored the performance of the different ultrasound modes, and the diagnosis was assessed on a seven-point BI-RADS scale.
Key findings of the study include:
Key findings of the study include:
· Sufficient ultrasound contrast agent flow was seen in 83 lesions through subharmonic imaging, but only in eight lesions through harmonic imaging.
· Subharmonic imaging depicted more anastomoses and vascularity than harmonic imaging, but the researchers found no differences in terms of pathology.
· Ultrasound modes achieved accuracies ranging from 79% to 85%, significantly better than the 72% seen in mammography.
· Subharmonic imaging also increased diagnostic confidence by 3% to 6%, but inter-reader agreements were medium to low.
- The best logistical regression model achieved a 96% accuracy by combining clinical reads and quantitative 3D subharmonic imaging parameters.
"It was a little bit disappointing that for the clinical readers alone, there was no significant improvement by going to the 3D subharmonic and harmonic mode relative to conventional modes," Forsberg said. "With that said, we still think we're relatively on target with this and can get something decent out of it."
