Clinical applications of photon-counting CT in neuroimaging

Photon-counting computed tomography (PCCT) is a next-generation CT imaging technology that markedly improves image quality while reducing radiation dose and image noise through single-photon detection and energy discrimination by photon detectors. At present, PCCT holds broad clinical application prospects in the field of neuroimaging, especially demonstrating unique advantages in the visualization of fine intracranial structures, the diagnosis and treatment monitoring of intracranial aneurysms, and the diagnosis and treatment of intracranial artery stenosis and spinal vascular lesions. In ultra-high-resolution (UHR) mode (slice thickness of 0.2 mm), PCCT of the head and neck arteries achieves high signal-to-noise ratios using BV64-BV72 convolution kernel reconstruction. With the digital subtraction angiography (DSA) as the gold standard, UHR-PCCTA shows sensitivity, specificity, accuracy, and inter-rater agreement of approximately 98.0%, 96.7%, 97.3%, and 0.95 (Kappa values), respectively, in diagnosing small intracranial aneurysms. In addition, UHR-PCCT significantly outperforms conventional energy-integrating detector CT (EID-CT) in identifying aneurysm irregularity, aneurysm wall, and intraluminal features. UHR-PCCT is expected to enable precise evaluation of the degree of arterial stenosis, potentially approaching the accuracy of DSA. With its multi-energy virtual monoenergetic reconstructions, it shows promise for quantitative analysis of intracranial athe-rosclerotic plaques and prediction of plaque rupture risk. Under sharp reconstruction kernels (e.g., BV72-BV80), PCCT enables clear visualization of intracranial arterial stents and residual aneurysms, offering a new noninvasive alternative to DSA for postope-rative monitoring of intracranial artery treatments. The diversified applications of PCCT in neuroimaging will lay a foundation for its better role in the diagnosis and treatment of neurological diseases. However, the widespread application of PCCT in the neurological field remains limited by factors such as restricted equipment availability, the need for imaging optimization in specific scenarios (e.g., small perforating arteries, severe calcifications, or metallic implants), and the lack of support from large-scale clinical validation data. In the future, it is necessary to gradually overcome these limitations through continued hardware upgrades, algorithmic optimization, and the advancement of multicenter prospective studies to fully unleash the clinical potential of PCCT.