Deep‐learning synthesized pseudo‐<scp>CT</scp> for <scp>MR</scp> high‐resolution pediatric cranial bone imaging (<scp>MR‐HiPCB</scp>)
Parna Eshraghi Boroojeni, Yasheng Chen, Paul K. Commean, Cihat Eldeniz, Gary B. Skolnick, Corinne Merrill, Kamlesh B. Patel, Hongyu An
Abstract
Purpose CT is routinely used to detect cranial abnormalities in pediatric patients with head trauma or craniosynostosis. This study aimed to develop a deep learning method to synthesize pseudo‐CT (pCT) images for MR high‐resolution pediatric cranial bone imaging to eliminating ionizing radiation from CT. Methods 3D golden‐angle stack‐of‐stars MRI were obtained from 44 pediatric participants. Two patch‐based residual UNets were trained using paired MR and CT patches randomly selected from the whole head (NetWH) or in the vicinity of bone, fractures/sutures, or air (NetBA) to synthesize pCT. A third residual UNet was trained to generate a binary brain mask using only MRI. The pCT images from NetWH (pCT NetWH ) in the brain area and NetBA (pCT NetBA ) in the nonbrain area were combined to generate pCT Com . A manual processing method using inverted MR images was also employed for comparison. Results pCT Com (68.01 ± 14.83 HU) had significantly smaller mean absolute errors (MAEs) than pCT NetWH (82.58 ± 16.98 HU, P < 0.0001) and pCT NetBA (91.32 ± 17.2 HU, P < 0.0001) in the whole head. Within cranial bone, the MAE of pCT Com (227.92 ± 46.88 HU) was significantly lower than pCT NetWH (287.85 ± 59.46 HU, P < 0.0001) but similar to pCT NetBA (230.20 ± 46.17 HU). Dice similarity coefficient of the segmented bone was significantly higher in pCT Com (0.90 ± 0.02) than in pCT NetWH (0.86 ± 0.04, P < 0.0001), pCT NetBA (0.88 ± 0.03, P < 0.0001), and inverted MR (0.71 ± 0.09, P < 0.0001). Dice similarity coefficient from pCT Com demonstrated significantly reduced age dependence than inverted MRI. Furthermore, pCT Com provided excellent suture and fracture visibility comparable to CT. Conclusion MR high‐resolution pediatric cranial bone imaging may facilitate the clinical translation of a radiation‐free MR cranial bone imaging method for pediatric patients.