An Exploratory Multi-reader, Multi-case Study Comparing Transmission Ultrasound to Mammography on Recall Rates and...

Three-dimensional Quantitative Transmission (QT) ultrasound imaging is an emerging modality for improving the detection and diagnosis of breast cancer. QT ultrasound has high resolution and high contrast to noise ratio, making it effective in evaluating breast tissue. This study compares radiologists' performance of noncancer recall rates and lesion detection rates using QT Ultrasound versus full-field digital mammography (FFDM) in a cross section of female subjects.

In this multi-reader multi-case (MRMC) study, we examined retrospective data from two clinical trials conducted at five sites. All subjects received FFDM and QT scans within 90 days. Data were analyzed in a reader study with full factorial design involving 22 radiologists and 108 breast cases (42 normal, 39 pathology-confirmed benign, and 27 pathology-confirmed cancer cases). The main results used a random-reader random-case analysis adjusted for location bias performed after a primary predefined random-reader fixed-case analysis.

The readers' mean rate of detecting lesions of any type was 4% higher (p-value > 0.05) with QT imaging. The mean non-cancer recall rate improved significantly, showing a decrease of 16% with QT (p-value = 0.03), at the expense of a 2% decrease in the mean cancer recall rate (p-value >0.05) in comparison to FFDM. Combining performance on cancer and noncancer recall rates, the mean area under the receiver operator curve of confidence scores improved significantly by 10% with QT (p-value = 0.01).

This MRMC study indicates that QT improves non-cancer recall rates without substantially affecting cancer recall rates. The main limitation is the small number of cases from retrospective data. A larger prospective MRMC study is warranted for further assessment.