Motion-stabilized background subtraction for fluorescence imaging

An imaging acquisition system for imaging a scene including at least one target body-part containing a fluorescent substance, the imaging acquisition system comprising at least:

• a light source configured to emit excitation light to illuminate the at least one target body-part, the excitation light being suitable for causing emission of fluorescent light from the target body-part;
• and
• a fluorescence camera having a fluorescence emission detection passband configured to allow detection of the fluorescent light emitted by the target body part;
• the imaging acquisition system being configured to perform a method comprising:
• obtaining a sequence of reflectance images acquired by a reflectance camera configured to detect reflected light due to an illumination condition different than the excitation light;
• while obtaining the sequence of reflectance images, acquiring, using the fluorescence camera, a sequence of fluorescence channel images including light images, acquired while using the light source to cause the target body-part to emit fluorescent light, alternating with dark images, acquired without using the light source to cause the target body-part to emit fluorescent light;
• determining a first reflectance image of said sequence of reflectance images associated with a first fluorescence channel image, the first fluorescence channel image having a first reference time;
• determining a second reflectance image of said sequence of reflectance images associated with a second fluorescence channel image acquired by the fluorescence camera consecutively to the first fluorescence channel image, the second fluorescence channel image having a second reference time;
• determining a transformation matrix based on a relative alignment of the first and second reflectance images;
• applying the transformation matrix to one of the first and second fluorescence channel images to align the first and second fluorescence channel images;
• performing a subtraction between said one of the first and second fluorescence channel images to which the transformation matrix has been applied and the other of the first and second fluorescence channel images to obtain a background-subtracted image;
• and
• outputting the background-subtracted image for displaying.

A computer program product comprising a computer readable storage medium including computer instructions that, when executed by a computing device of an imaging acquisition system, the imaging acquisition system is configured to:

• obtain a sequence of reflectance images acquired by a reflectance camera configured to detect reflected light due to an illumination condition different than the excitation light;
• while obtaining the sequence of reflectance images, acquiring, using the fluorescence camera, a sequence of fluorescence channel images including light images, acquired while using the light source to cause the target body-part to emit fluorescent light, alternate with dark images, acquired without using the light source to cause the target body-part to emit fluorescent light;
• determine a first reflectance image of said sequence of reflectance images associated with a first fluorescence channel image, the first fluorescence channel image having a first reference time;
• determine a second reflectance image of said sequence of reflectance images associated with a second fluorescence channel image acquired by the fluorescence camera consecutively to the first fluorescence channel image, the second fluorescence channel image having a second reference time;
• determine a transformation matrix based on a relative alignment of the first and second reflectance images;
• apply the transformation matrix to one of the first and second fluorescence channel images to align the first and second fluorescence channel images;
• perform a subtraction between said one of the first and second fluorescence channel images to which the transformation matrix has been applied and the other of the first and second fluorescence channel images to obtain a background-subtracted image;
• and
• output the background-subtracted image for displaying.