A magnetic resonance scanner, comprising: a main magnet configured to generate a B 0 field; gradient coils and a gradient coil controller which are both configured to generate magnetic field gradients across the B 0 field; one or more RF coils (16,50) configured to transmit B 1 pulses and receive magnetic resonance signals; an RF transmitter configured to transmit B 1 pulses to the RF coils to excite and manipulate magnetic resonance; an RF receiver configured to demodulate received magnetic resonance signals into k-space data lines; one or more processors connected to the gradient coil controller, the RF transmitter, and the RF receiver which are programmed to: control the RF transmitter and the gradient coil controller to implement an interleaved multi-slice 2D imaging sequence which in each of a plurality of TRs generates a first and a second navigation k-space data line and at least one image k-space data line for each of a plurality of slices, wherein the first and second navigation k-space data lines are acquired in orthogonal directions; reconstruct the first navigation k-space data lines from the plurality of slices into a first navigation image, wherein the first navigation image is a two-dimensional image; reconstruct the second navigation k-space data lines from the plurality of slices into a second navigation image, wherein the second navigation image is a two-dimensional image, wherein the first and second navigation images are orthogonal to each other and to the image slices; and compare successive navigation images to detect and adjust for 3D motion. a main magnet configured to generate a B 0 field; gradient coils and a gradient coil controller which are both configured to generate magnetic field gradients across the B 0 field; one or more RF coils (16,50) configured to transmit B 1 pulses and receive magnetic resonance signals; an RF transmitter configured to transmit B 1 pulses to the RF coils to excite and manipulate magnetic resonance; an RF receiver configured to demodulate received magnetic resonance signals into k-space data lines; one or more processors connected to the gradient coil controller, the RF transmitter, and the RF receiver which are programmed to: control the RF transmitter and the gradient coil controller to implement an interleaved multi-slice 2D imaging sequence which in each of a plurality of TRs generates a first and a second navigation k-space data line and at least one image k-space data line for each of a plurality of slices, wherein the first and second navigation k-space data lines are acquired in orthogonal directions; reconstruct the first navigation k-space data lines from the plurality of slices into a first navigation image, wherein the first navigation image is a two-dimensional image; reconstruct the second navigation k-space data lines from the plurality of slices into a second navigation image, wherein the second navigation image is a two-dimensional image, wherein the first and second navigation images are orthogonal to each other and to the image slices; and compare successive navigation images to detect and adjust for 3D motion. control the RF transmitter and the gradient coil controller to implement an interleaved multi-slice 2D imaging sequence which in each of a plurality of TRs generates a first and a second navigation k-space data line and at least one image k-space data line for each of a plurality of slices, wherein the first and second navigation k-space data lines are acquired in orthogonal directions; reconstruct the first navigation k-space data lines from the plurality of slices into a first navigation image, wherein the first navigation image is a two-dimensional image; reconstruct the second navigation k-space data lines from the plurality of slices into a second navigation image, wherein the second navigation image is a two-dimensional image, wherein the first and second navigation images are orthogonal to each other and to the image slices; and compare successive navigation images to detect and adjust for 3D motion.