Table 1 Biomechanical and technical problems.
Problem | Description | Effect on cell detection and tracking |
|---|---|---|
Plasticity (Pla) | High variability in cell shape, such as elongation and formation of protrusions | Parts of the same cell not detected or associated to other cells |
Contact (Con) | Close proximity of two cells with the same color | Cells merged in a single object. Track interrupted or switched |
High background or low signal to noise ratio (BG) | Background or other objects (collagen fibers, auto-fluorescence, cell debris) appear in the same channel of cells with a similar brightness | Inaccurate cell detection, track interruption, tracking of third objects |
Fluorescence variation (Flu) | The intensity of fluorescent cells changes during acquisition. Reasons include photo-bleaching and migration in different areas of the tissue | Inaccurate cell detection and track interruption |
High migrating velocity (Vel) | Migration velocity greater than the cell size in a time step (absence of overlap) | Track interruption and aliasing if assumptions for interpolation rules for poorly visible cells are not correct. Deformation of cell shapes |
Appearance and Disappearance (A/D) | Sudden or progressive appearance/disappearance of a cell, either close to the boundaries of the field of view or in proximity to a blood or lymphatic vessel | Track duration is less or equal than the length of the video. Tracking errors if interpolation rules for poorly visible cells are not correct |
Movement of the sample (Mov) | Shifting, drifting or fluctations of the sample due to the movement of the animal or insufficient isolation from breathing, peristalsis and heartbeat | Non-rigid deformation of the tissue, discontinuities in tracks |
Microscope instability (Ins) | Noise introduced either by oscillations in the laser power or in the sensitivity of the photo-detectors, resulting in bands or bright spots | Detection of larger or smaller objects. Appearance of the background, disappearance of cells |
Large areas (Lar) | Non-uniform brightness | Frequent detection and tracking errors if parameters are not adjusted locally. Increased computational time |
Channel specificity (Spe) | Emitted spectrum is captured in more than one channel | Mis-detection and increased contacts with the background |
Density (Den) | High number of cells in close proximity | Track switching for tightly interacting cells and mis-detection |
