Rapid Generation of Subject-Specific Human Models With Detailed Tissue Structures for Timely Individualized SAR Assessment.
Authors
Affiliations (2)
Affiliations (2)
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China.
- Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China.
Abstract
To enable the rapid generation of subject-specific whole-body anatomical models for patient-specific prediction of torso-local specific absorption rate (SAR) in MRI. A 6-s 3D gradient-echo MRI sequence was used to acquire data within the imaging field of view (FOV). Major tissue types were automatically segmented using a deep learning model trained via a semi-supervised strategy combining teacher-student learning and partial-category annotations. A full-body geometry was reconstructed from depth data captured by a 3D camera, thereby extending the model beyond the FOV. The MRI-derived anatomical segmentation and camera-based external geometry were co-registered and fused into a seamless, subject-specific human model. Human models were generated in approximately 20 s per subject, including MRI acquisition and processing. Accurate tissue segmentation and robust body reconstruction were achieved. Validation on the Duke numerical phantom yielded an average peak SAR<sub>10g</sub> error < 2%. In vivo <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow><msubsup><mi>B</mi> <mn>1</mn> <mo>+</mo></msubsup> </mrow> <annotation>$$ {B}_1^{+} $$</annotation></semantics> </math> field comparisons in 20 volunteers showed a normalized root-mean-square error (NRMSE) of 9.50%. The models preserved subject-specific anatomy and were suitable for electromagnetic simulation. A hybrid framework integrating ultrafast MRI, depth data scanning and deep learning enables rapid construction of subject-specific human models, supporting practical, online SAR monitoring in clinical MRI.