  Significance: Confocal laser scanning enables optical sectioning in fiber
bundle endomicroscopy but limits the frame rate. To be able to better explore
tissue morphology it is useful to stitch sequentially acquired frames into a
mosaic. However, low frame rates limit the maximum probe translation speed.
Line-scanning confocal endomicroscopy provides higher frame rates, but residual
out-of-focus light degrades images. Subtraction based approaches can suppress
this residue at the expense of introducing motion artifacts.
  Aim: To generate high frame rate endomicroscopy images with improved optical
sectioning, we develop a high-speed subtraction method that only requires the
acquisition of a single camera frame.
  Approach: The rolling shutter of a CMOS camera acts as both the aligned and
offset detector slits required for subtraction-based sectioning enhancement.
Two images of the bundle are formed on different regions of the camera,
allowing both images to be acquired simultaneously.
  Results: We confirm improved optical sectioning compared to conventional
line-scanning, particularly far from focus, and show that motion artifacts are
not introduced. We demonstrate high-speed mosaicing at frame rates of up to 240
Hz.
  Conclusion: High-speed acquisition of optically sectioned images using the
new subtraction based approach leads to improved mosaicing at high frame rates.
