Perfusion Maps Acquired From Dynamic Angiography MRI Using Deep Learning Approaches

Background A typical stroke MRI protocol includes perfusion‐weighted imaging (PWI) and MR angiography (MRA), requiring a second dose of contrast agent. A deep learning method to acquire both PWI and MRA with single dose can resolve this issue. Purpose To acquire both PWI and MRA simultaneously using deep learning approaches. Study type Retrospective. Subjects A total of 60 patients (30–73 years old, 31 females) with ischemic symptoms due to occlusion or ≥50% stenosis (measured relative to proximal artery diameter) of the internal carotid artery, middle cerebral artery, or anterior cerebral artery. The 51/1/8 patient data were used as training/validation/test. Field Strength/Sequence A 3 T, time‐resolved angiography with stochastic trajectory (contrast‐enhanced MRA) and echo planar imaging (dynamic susceptibility contrast MRI, DSC‐MRI). Assessment We investigated eight different U‐Net architectures with different encoder/decoder sizes and with/without an adversarial network to generate perfusion maps from contrast‐enhanced MRA. Relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), mean transit time (MTT), and time‐to‐max (T max ) were mapped from DSC‐MRI and used as ground truth to train the networks and to generate the perfusion maps from the contrast‐enhanced MRA input. Statistical Tests Normalized root mean square error, structural similarity (SSIM), peak signal‐to‐noise ratio (pSNR), DICE, and FID scores were calculated between the perfusion maps from DSC‐MRI and contrast‐enhanced MRA. One‐tailed t ‐test was performed to check the significance of the improvements between networks. P values < 0.05 were considered significant. Results The four perfusion maps were successfully extracted using the deep learning networks. U‐net with multiple decoders and enhanced encoders showed the best performance (pSNR 24.7 ± 3.2 and SSIM 0.89 ± 0.08 for rCBV). DICE score in hypo‐perfused area showed strong agreement between the generated perfusion maps and the ground truth (highest DICE: 0.95 ± 0.04). Data Conclusion With the proposed approach, dynamic angiography MRI may provide vessel architecture and perfusion‐relevant parameters simultaneously from a single scan. Evidence Level 3 Technical Efficacy Stage 5