UltraschallCT

UltraschallCT, or ultrasound computed tomography (USCT), is a medical imaging modality that uses arrays of ultrasound transducers and computational reconstruction to visualize tissue properties. Unlike conventional ultrasound, which provides real-time grayscale images, and unlike X-ray computed tomography, which relies on X-ray attenuation, USCT aims to map the acoustic properties of tissue, such as the speed of sound and attenuation, in three dimensions.

The typical USCT system comprises multiple transducers arranged around the region of interest. Short ultrasound pulses are emitted and detected by receivers, producing data from which the internal structure is reconstructed. Reconstruction methods solve an inverse problem and may utilize transmission data, reflection data, or a combination. Common algorithmic approaches include delay-and-sum beamforming, time-reversal techniques, filtered backprojection, and full-waveform inversion to produce quantitative maps of tissue properties.

Applications and status: The most active area is breast imaging, where USCT is explored for cancer detection and characterization, with the goal of improving diagnostic accuracy while avoiding ionizing radiation. Other potential targets include thyroid and other body regions. USCT is primarily in the research and development phase, with several feasibility studies and clinical trials reported. While promising for providing quantitative tissue-property information, it faces challenges before broad clinical adoption, including achieving higher spatial resolution, ensuring robust data acquisition in the presence of motion, and managing computational demands.

Advantages and limitations: USCT offers non-ionizing imaging and the potential for quantitative tissue-property assessment. It can complement conventional ultrasound and other modalities. Limitations include generally lower spatial resolution compared with X-ray CT, sensitivity to coupling and motion, longer data acquisition and processing times, and ongoing work to standardize hardware and reconstruction methods.