Deep Learning-Based Iodine Contrast Augmentation for Suboptimally Enhanced CT Pulmonary Angiography: Implications for Pulmonary Embolism Diagnosis

<b>Background/Objectives</b>: This study aimed to assess the impact of a deep learning-based iodine contrast augmentation (DLCA) algorithm on image quality and diagnostic performance for pulmonary embolism (PE) detection in suboptimally enhanced CT pulmonary angiography (CTPA). <b>Methods</b>: We retrospectively included 103 suboptimal CTPA cases performed between May 2020 and March 2025. Image quality (attenuation, noise, SNR, and CNR) was compared between original and DLCA-processed images. Diagnostic performance for PE detection was assessed per segment, with and without DLCA processing. <b>Results</b>: DLCA increased pulmonary artery opacification by 57.7% and reduced noise by 56.7%, significantly improving SNR (13.2 → 47.5) and CNR (8.7 → 37.2; both <i>p</i> < 0.001). Incorporation of DLCA-processed images improved diagnostic accuracy for overall (AUC: 0.874/0.845 → 0.958/0.938), central (0.939/0.895 → 0.987/0.972), and peripheral (0.824/0.807 → 0.935/0.912) PE detection (all <i>p</i> ≤ 0.003). In suboptimal CTPA, a pulmonary artery attenuation threshold of 130 HU was identified, above which DLCA processing significantly improved PE detection accuracy compared with original images in both readers (<i>p</i> < 0.001). <b>Conclusions</b>: DLCA processing in suboptimal CTPA significantly enhances image quality and diagnostic accuracy for PE detection, providing a promising strategy to optimize scans without additional contrast or radiation.