A method for imaging a biological sample, the sample comprising blood comprising diffusors and solid tissue, the method comprising: - an imaging step comprising the following operations: • an emitting operation in which unfocused ultrasound waves in the region of interest are emitted during a time interval, the ratio of the number of unfocused ultrasound waves over the time interval being superior or equal to 100 unfocused ultrasound waves per second, • a collecting operation in which retroreflected waves from the diffusors of the given region of interest are collected, and • an image formation operation in which different observations of a region of interest are generated based on the collected retroreflected waves, each observation being characterized by a different and partially spatially decorrelated point spread function associating a signal to each location of the region of interest, the signal comprising a first contribution representative of the diffusors of blood vessels within the location, a second contribution representative of the tissue diffusors and a third contribution representative of blood signal associated to blood diffusors outside of the location, the second and third contribution being undesired, the imaging step being iterated M times to obtain observation sets of M temporal realizations of the region of interest, M being superior or equal to 10, - a filtering step for reducing the second contribution of each of the observation sets, and - an estimating step in which, for each location of the region of interest, the blood flow signal is estimated, the estimating step comprising the following operations: • applying a statistical analysis on the observations of each set to discriminate the first contribution and the third contribution by the use of the spatial decorrelation of blood signals originating from distinct locations through the statistical analysis operation based on the joint variability of the observations sets, and • calculating an estimate of the component of the blood flow signal based on the first contribution. - an imaging step comprising the following operations: • an emitting operation in which unfocused ultrasound waves in the region of interest are emitted during a time interval, the ratio of the number of unfocused ultrasound waves over the time interval being superior or equal to 100 unfocused ultrasound waves per second, • a collecting operation in which retroreflected waves from the diffusors of the given region of interest are collected, and • an image formation operation in which different observations of a region of interest are generated based on the collected retroreflected waves, each observation being characterized by a different and partially spatially decorrelated point spread function associating a signal to each location of the region of interest, the signal comprising a first contribution representative of the diffusors of blood vessels within the location, a second contribution representative of the tissue diffusors and a third contribution representative of blood signal associated to blood diffusors outside of the location, the second and third contribution being undesired, the imaging step being iterated M times to obtain observation sets of M temporal realizations of the region of interest, M being superior or equal to 10, • an emitting operation in which unfocused ultrasound waves in the region of interest are emitted during a time interval, the ratio of the number of unfocused ultrasound waves over the time interval being superior or equal to 100 unfocused ultrasound waves per second, • a collecting operation in which retroreflected waves from the diffusors of the given region of interest are collected, and • an image formation operation in which different observations of a region of interest are generated based on the collected retroreflected waves, each observation being characterized by a different and partially spatially decorrelated point spread function associating a signal to each location of the region of interest, the signal comprising a first contribution representative of the diffusors of blood vessels within the location, a second contribution representative of the tissue diffusors and a third contribution representative of blood signal associated to blood diffusors outside of the location, the second and third contribution being undesired, - a filtering step for reducing the second contribution of each of the observation sets, and - an estimating step in which, for each location of the region of interest, the blood flow signal is estimated, the estimating step comprising the following operations: • applying a statistical analysis on the observations of each set to discriminate the first contribution and the third contribution by the use of the spatial decorrelation of blood signals originating from distinct locations through the statistical analysis operation based on the joint variability of the observations sets, and • calculating an estimate of the component of the blood flow signal based on the first contribution. • applying a statistical analysis on the observations of each set to discriminate the first contribution and the third contribution by the use of the spatial decorrelation of blood signals originating from distinct locations through the statistical analysis operation based on the joint variability of the observations sets, and • calculating an estimate of the component of the blood flow signal based on the first contribution.