A compact meta-differentiator is proposed for achieving isotropically high-contrast ultrasonic imaging. This device enhances imaging contrast without the need for contrast agents or external physical fields. It incorporates an amplitude metagrating for linear transmission along the radial direction and a phase metagrating that utilizes focus and spiral phases with a first-order topological charge. The design enables 2D isotropic edge enhancements for high-contrast ultrasonic imaging. Theoretical analysis, numerical simulations, and experimental validation confirm the effectiveness of this technique in distinguishing amplitude objects with isotropic edge enhancements. The method also enables accurate detection of both phase objects and artificial biological models. This breakthrough opens new opportunities for applications in medical diagnosis and nondestructive testing. Ultrasound imaging is crucial in biomedical engineering for its deep penetration and non-ionizing nature. However, traditional techniques rely on impedance differences, resulting in poor contrast for acoustically transparent targets. To address this, specialized ultrasound contrast agents and magnetic contrast agents have been introduced. However, these techniques are expensive and have limitations, including the risk of allergic reactions and limited tissue penetration. Photoacoustic imaging has been developed as an alternative, detecting ultrasonic waves induced by laser pulses in superficial tissues. Current approaches primarily rely on contrast agents or external physical fields to enhance acoustic contrast. However, these techniques are expensive and have limitations. In contrast, optical phase contrast methods like Zernike phase contrast and differential interference contrast have significantly improved optical contrast. Recent advancements in optical computational metamaterials, such as metasurfaces and photonic crystals, have demonstrated exceptional capabilities in edge-enhanced imaging through spatial differentiation. These advancements provide a crucial tool for identifying and highlighting boundaries between different regions of objects. Inspired by advances in optics, researchers have investigated acoustic computational metamaterials for differentiation operations. This includes the use of metasurfaces based on the Fourier approach or phononic crystals employing the Green's function method. However, these methods have limitations, including anisotropic edge enhancements and incompatibility with compact integrated systems. The proposed compact meta-differentiator based on acoustic composite meta-gratings enables 2D isotropic edge enhancements for high-contrast ultrasonic imaging. The design incorporates an amplitude metagrating for linear transmission along the radial direction and a phase metagrating composed of focus and spiral phases carrying a first-order topological charge. This configuration allows for direct manipulation of the wavevector distribution, enhancing higher values while maintaining a central zero in the wavevector space to achieve 2D spatial differentiation. The processed imaging of amplitude objects exhibits distinct isotropic edge contrast enhancements, validated through theoretical analysis, numerical simulation, and experimental verification. Furthermore, the accurate and reliable isotropic edge-enhanced detection of both phase objects and artificial biological models is demonstrated through 2D spatial differentiation. Theoretical analysis of isotropic spatial differentiation shows that the meta-differentiator can achieve isotropic edge enhancements. The PSF of the focus metasurface resembles a diffractionA compact meta-differentiator is proposed for achieving isotropically high-contrast ultrasonic imaging. This device enhances imaging contrast without the need for contrast agents or external physical fields. It incorporates an amplitude metagrating for linear transmission along the radial direction and a phase metagrating that utilizes focus and spiral phases with a first-order topological charge. The design enables 2D isotropic edge enhancements for high-contrast ultrasonic imaging. Theoretical analysis, numerical simulations, and experimental validation confirm the effectiveness of this technique in distinguishing amplitude objects with isotropic edge enhancements. The method also enables accurate detection of both phase objects and artificial biological models. This breakthrough opens new opportunities for applications in medical diagnosis and nondestructive testing. Ultrasound imaging is crucial in biomedical engineering for its deep penetration and non-ionizing nature. However, traditional techniques rely on impedance differences, resulting in poor contrast for acoustically transparent targets. To address this, specialized ultrasound contrast agents and magnetic contrast agents have been introduced. However, these techniques are expensive and have limitations, including the risk of allergic reactions and limited tissue penetration. Photoacoustic imaging has been developed as an alternative, detecting ultrasonic waves induced by laser pulses in superficial tissues. Current approaches primarily rely on contrast agents or external physical fields to enhance acoustic contrast. However, these techniques are expensive and have limitations. In contrast, optical phase contrast methods like Zernike phase contrast and differential interference contrast have significantly improved optical contrast. Recent advancements in optical computational metamaterials, such as metasurfaces and photonic crystals, have demonstrated exceptional capabilities in edge-enhanced imaging through spatial differentiation. These advancements provide a crucial tool for identifying and highlighting boundaries between different regions of objects. Inspired by advances in optics, researchers have investigated acoustic computational metamaterials for differentiation operations. This includes the use of metasurfaces based on the Fourier approach or phononic crystals employing the Green's function method. However, these methods have limitations, including anisotropic edge enhancements and incompatibility with compact integrated systems. The proposed compact meta-differentiator based on acoustic composite meta-gratings enables 2D isotropic edge enhancements for high-contrast ultrasonic imaging. The design incorporates an amplitude metagrating for linear transmission along the radial direction and a phase metagrating composed of focus and spiral phases carrying a first-order topological charge. This configuration allows for direct manipulation of the wavevector distribution, enhancing higher values while maintaining a central zero in the wavevector space to achieve 2D spatial differentiation. The processed imaging of amplitude objects exhibits distinct isotropic edge contrast enhancements, validated through theoretical analysis, numerical simulation, and experimental verification. Furthermore, the accurate and reliable isotropic edge-enhanced detection of both phase objects and artificial biological models is demonstrated through 2D spatial differentiation. Theoretical analysis of isotropic spatial differentiation shows that the meta-differentiator can achieve isotropic edge enhancements. The PSF of the focus metasurface resembles a diffraction