for intravascular oct (iVoct) images, we developed an automated atherosclerotic plaque characterization method that used a hybrid learning approach, which combined deep-learning convolutional and hand-crafted, lumen morphological features. processing was done on innate A-line units with labels fibrolipidic (fibrous tissue followed by lipidous tissue), fibrocalcific (fibrous tissue followed by calcification), or other. We trained/tested on an expansive data set (6,556 images), and performed an active learning, relabeling step to improve noisy ground truth labels. conditional random field was an important post-processing step to reduce classification errors. Sensitivities/ specificities were 84.8%/97.8% and 91.4%/95.7% for fibrolipidic and fibrocalcific plaques, respectively. Over lesions, en face classification maps showed automated results that agreed favorably to manually labeled counterparts. Adding lumen morphological features gave statistically significant improvement (p < 0.05), as compared to classification with convolutional features alone. Automated assessments of clinically relevant plaque attributes (arc angle and length), compared favorably to those from manual labels. our hybrid approach gave statistically improved results as compared to previous A-line classification methods using deep learning or hand-crafted features alone. This plaque characterization approach is fully automated, robust, and promising for live-time treatment planning and research applications. Intravascular optical coherence tomography (IVOCT) is an important technology for planning and assessment of interventional, percutaneous treatments of coronary artery disease. IVOCT is a high contrast, high-resolution imaging modality that uses near-infrared light 1. Compared to intravascular ultrasound (IVUS), this modality provides better image resolution with axial resolution ranging from 12 to 18 μm (as compared to 150-250 μm from IVUS) and lateral resolution ranging from 20 to 90 μm (as compared to 150-300 μm from IVUS) 1. IVOCT allows to determine different plaque components such as fibrous, lipidous, and calcified tissues, and is the only modality that can identify thin cap fibroatheroma 2. IVOCT is used for clinical, live-time intervention planning, and stent deployment assessment. IVOCT-guided percutaneous coronary intervention (PCI) brings valuable benefit for patient treatment as compared to PCI guided by X-ray angiography alone 3. In addition, IVOCT is used for clinical research studies such as the calcium scoring analysis 4 and calcium crack formation 5. Although IVOCT is clearly an excellent method for intravascular imaging of plaque, it has limitations. One is the cost of transducers. Another is tissue penetration depth, especially in the presence of lipidous plaque. Another is the need for a physician trained in visual interpretation of IVOCT images who is willing to take the time to examine images during a stressful procedure. A single IVOCT pullback typically generates 300-500 image frames resulting in data overload. Even ...