Medical Image Computing and Computer-Assisted Intervention -- MICCAI 2015
We present a 2D to 3D registration framework that compensates for prostate motion and deformations during freehand prostate biopsies. It has two major components: 1) a trajectory-based rigid registration to account for gross motions of the prostate; and 2) a non-rigid registration constrained by a finite element model (FEM) to adjust for residual motion and deformations. For the rigid alignment, we constrain the ultrasound probe tip in the live 2D imaging plane to the tracked trajectory from the pre-procedure 3D ultrasound volume. This ensures the rectal wall approximately coincides between the images. We then apply a FEM-based technique to deform the volume based on image intensities. We validate the proposed framework on 10 prostate biopsy patients, demonstrating a mean target registration error (TRE) of 4.63 mm and 3.15 mm for rigid and FEM-based components, respectively.
The enumeration and capture of circulating tumor cells (CTCs) has great potential clinical value by offering a non-invasive means to access tumor materials to diagnose disease and monitor treatment efficacy. Conventional immunoenrichment of CTCs may fail to capture cells with low surface antigen expression. Micropore filtration presents a compelling label-free alternative that enriches for CTCs using their biophysical rather than biochemical characteristics. However, this strategy is prone to clogging of the filter microstructure, which dramatically reduces selectivity after processing large numbers of cells. Here, we use the resettable cell trap (RCT) mechanism to separate cells based on their distinct size and deformability using an adjustable aperture that can be periodically cleared to prevent clogging. Samples were filtered multiple times on chip to improve selectivity. Repeated filtrations achieved over 900x enrichment and over 90% yield of UM-UC13 bladder cancer cells doped into 2x diluted whole blood. CTCs were successfully identified using the RCT device followed by single-cell spectral analysis from patients with metastatic castration-resistant prostate cancer (mCRPC). The RCT device identified 81.8% (18/22) patients with >=5 CTCs per 7.5 ml of blood with a mean count of 257. Within the same patient group, the CellSearch measured >=5 CTCs in only 40.9% (9/22) patients with a mean of 25 CTCs per 7.5 ml of blood. The RCT device identified significantly more CTCs compared to the CellSearch® system and is comparable to other reported label-free separation techniques.