Treatment for Basal Cell Carcinoma (BCC) includes an excisional surgery to remove cancerous tissues, using a cautery tool to make burns along a defined resection margin around the tumor. Margin evaluation occurs post-surgically, requiring repeat surgery if positive margins are detected. Rapid Evaporative Ionization Mass Spectrometry (REIMS) can help distinguish healthy and cancerous tissue but does not provide spatial information about the cautery tool location where the spectra are acquired. We propose using intraoperative surgical video recordings and deep learning to provide surgeons with guidance to locate sites of potential positive margins. Frames from 14 intraoperative videos of BCC surgery were extracted and used to train a sequence of networks. The first network extracts frames showing surgery in-progress, then, an object detection network localizes the cautery tool and resection margin. Finally, our burn prediction model leverages the effectiveness of both a Long Short-Term Memory (LSTM) network and a Receiver Operating Characteristic (ROC) curve to accurately predict when the surgeon is cutting. The cut identifications will be used in the future for synchronization with iKnife data to provide localizations when cuts are predicted. The model was trained with four-fold cross-validation on a patient-wise split between training, validation, and testing sets. Average recall over the four folds of testing for the LSTM and ROC were 0.80 and 0.73, respectively. The video-based approach is simple yet effective at identifying tool-to-skin contact instances and may help guide surgeons, enabling them to deliver precise treatments in combination with iKnife data.
Up to 35% of breast-conserving surgeries fail to resect all the tumors completely. Ideally, machine learning methods using the iKnife data, which uses Rapid Evaporative Ionization Mass Spectrometry (REIMS), can be utilized to predict tissue type in real-time during surgery, resulting in better tumor resections. As REIMS data is heterogeneous and weakly labeled, and datasets are often small, model performance and reliability can be adversely affected. Self-supervised training and uncertainty estimation of the prediction can be used to mitigate these challenges by learning the signatures of input data without their label as well as including predictive confidence in output reporting. We first design an autoencoder model using a reconstruction pretext task as a self-supervised pretraining step without considering tissue type. Next, we construct our uncertainty-aware classifier using the encoder part of the model with Masksembles layers to estimate the uncertainty associated with its predictions. The pretext task was trained on 190 burns collected from 34 patients from Basal Cell Carcinoma iKnife data. The model was further trained on breast cancer data comprising of 200 burns collected from 15 patients. Our proposed model shows improvement in sensitivity and uncertainty metrics of 10% and 15.7% over the baseline, respectively. The proposed strategies lead to improvements in uncertainty calibration and overall performance, toward reducing the likelihood of incomplete resection, supporting removal of minimal non-neoplastic tissue, and improved model reliability during surgery. Future work will focus on further testing the model on intraoperative data and additional exvivo data following collection of more breast samples.
Surgical excision for basal cell carcinoma (BCC) is a common treatment to remove the affected areas of skin. Minimizing positive margins around excised tissue is essential for successful treatment. Residual cancer cells may result in repeat surgery; however, detecting remaining cancer can be challenging and time-consuming. Using chemical signal data acquired while tissue is excised with a cautery tool, the iKnife system can discriminate between healthy and cancerous tissue but lacks spatial information, making it difficult to navigate back to suspicious margins. Intraoperative videos of BCC excision allow cautery locations to be tracked, providing the sites of potential positive margins. We propose a deep learning approach using convolutional neural networks to recognize phases in the videos and subsequently track the cautery location, comparing two localization methods (supervised and semi-supervised). Phase recognition was used for preprocessing to classify frames as showing the surgery or the start/stop of iKnife data acquisition. Only frames designated as showing the surgery were used for cautery localization. Fourteen videos were recorded during BCC excisions with iKnife data collection. On unseen testing data (2 videos, 1,832 frames), the phase recognition model showed an overall accuracy of 86%. Tool localization performed with a mean average precision of 0.98 and 0.96 for supervised and semisupervised methods, respectively, at a 0.5 intersection over union threshold. Incorporating intraoperative phase data with tool tracking provides surgeons with spatial information about the cautery tool location around suspicious regions, potentially improving the surgeon's ability to navigate back to the area of concern.
PURPOSE: Basal Cell Carcinoma (BCC) is the most common cancer in the world. Surgery is the standard treatment and margin assessment is used to evaluate the outcome. The presence of cancerous cells at the edge of resected tissue i.e., positive margin, can negatively impact patient outcomes and increase the probability of cancer recurrence. Novel mass spectrometry technologies paired with machine learning can provide surgeons with real-time feedback about margins to eliminate the need for resurgery. To our knowledge, this is the first study to report the performance of cancer detection using Graph Convolutional Networks (GCN) on mass spectrometry data from resected BCC samples. METHODS: The dataset used in this study is a subset of an ongoing clinical data acquired by our group and annotated with the help of a trained pathologist. There is a total number of 190 spectra in this dataset, including 127 normal and 63 BCC samples. We propose single-layer and multi-layer conversion methods to represent each mass spectrum as a structured graph. The graph classifier is developed based on the deep GCN structure to distinguish between cancer and normal spectra. The results are compared with the state of the art in mass spectra analysis. RESULTS: The classification performance of GCN with multi-layer representation without any data augmentation is comparable to the previous studies that have used augmentation. CONCLUSION: The results indicate the capability of the proposed graph-based analysis of mass spectrometry data for tissue characterization or real-time margin assessment during cancer surgery.
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