Determining the time-delay of a mass spectrometry-based tissue sensor

Abstract

Breast cancer commonly requires surgical treatment. A procedure used to remove breast cancer is lumpectomy, which removes a minimal healthy tissue margin surrounding the tumor, called a negative margin. A cancer-free margin is difficult to achieve because tumors are not visible or palpable, and the breast deforms during surgery. One notable solution is Rapid Evaporative Ionization Mass Spectrometry (REIMS), which differentiates tumor from healthy tissue with high accuracy from the vapor generated by the surgical cautery. REIMS combined with navigation could detect where the surgical cautery breaches tumor tissue. However, fusing position tracking and REIMS data for navigation is challenging. REIMS has a time-delay dependent on a series of factors. Our objective was to evaluate REIMS time-delay for surgical navigation. The average time-delay of REIMS classifications was measured by video recording. Incisions and corresponding REIMS classifications were measured in tissue samples. We measured the time-delay between physical incision of the tissue and tissue classification. We measured the typical timing of incisions by tracking the cautery in five lumpectomy procedures. The average REMIS time delay was found to be 2.1 ± 0.36 s (average ± SD), with a 95% confidence interval of 0.08 s. The average time between incisions was 2.5 ± 0.87 s. In conclusion, the variation in REIMS tissue classification time-delay allows localization of the tracked incision where the tissue sample originates. REIMS could be used to update surgeons about the location of cancerous tissue with only a few seconds of delay.