Every Drop (Photon) Counts

Abstract Photon-counting detector computed tomography (PCD-CT) is a breakthrough innovation over conventional single-energy and dual-energy CT equipped with energy-integrating detectors (EID). Because of increased spatial resolution and improved material differentiation, PCD-CT aims at improving the diagnosis of various abdominal conditions. This technology offers several advantages over EID-based CT scanners, including higher spatial and contrast resolution, reduced electronic noise, and low radiation dose exposure. Additionally, because spectral information is generated within the detectors, PCD-CT offers the possibility of routine spectral examinations and refines material decomposition through available multienergy imaging, further enhancing tissue characterization and image contrast. With most scientific literature focused on cardiovascular applications, abdominal imaging is an open field for technical and clinical research in PCD-CT. This review aims to provide a general overview of the technical principles of PCD-CT, its applications in abdominal imaging, and to summarize the main literature findings of its clinical applications in the liver, pancreas, adrenals, genitourinary system, bowel, peritoneum, and abdominal vessels. We will also highlight the pros and cons observed in clinical practice and offer insights into potential future developments of PCD-CT in abdominal imaging.