CV
Curriculum Vitae
Xupeng (Zack) Zhang — M.S.E. student in Electrical and Computer Engineering at Johns Hopkins University, working on machine learning for medical imaging and healthcare in the LDR Group.
Education
University of California, Davis
Sep 2021 – Mar 2025Research Experience
ROI-Centered MRI–MRA Registration for Trigeminal Neuralgia
Nov 2025 – Present- Reframed MRI–TOF-MRA fusion for trigeminal neuralgia as an ROI-centered neurovascular evaluation problem rather than generic whole-brain registration; first-author manuscript under review at IEEE Transactions on Medical Imaging.
- Built the end-to-end preprocessing, registration, and evaluation pipeline over a 149-patient microvascular-decompression cohort with 298 clinician-annotated trigeminal ROIs; released the benchmark and evaluation code publicly.
- Benchmarked six registration pipelines (ANTs Affine/SyN, ConvexAdam, FireANTs, EasyReg, SynthMorph) and showed that image-similarity, vessel-separability, and downstream localization metrics do not co-rank methods.
- Identified a volume confound in the standard one-sided vessel distance (Spearman ρ = −0.53, versus +0.08 in the reverse direction): common metrics systematically favor methods producing larger vessel trees under partial clinical annotations.
- Designed and ran a blinded two-neurosurgeon reader study over 100 stratified ROIs, exposing globally implausible registrations hidden by favorable local metrics — the best-scoring method failed at the whole-brain level in 71 of 100 cases.
T2-Only Cerebral Vessel Segmentation via Teacher–Student Learning
Mar 2026 – Present- Investigated whether cerebral vessels can be segmented from routinely acquired T2 MRI alone, using paired MRA only as a training-time supervision source — removing the MRA dependency that constrains the work above.
- Repurposed the VesselFM foundation model as an MRA-side teacher — it collapses when applied directly to T2 (Dice 0.041) — warping its pseudo-labels into T2 space to supervise a 3D nnU-Net student that requires no MRA at inference.
- Reached Dice 0.489 ± 0.043 on held-out subjects from a 568-subject IXI cohort — +0.448 over zero-shot VesselFM and within 0.072 of an oracle trained on manual MRA labels, using no manual annotation.
- Separated label quality from label quantity: at identical training-set size, teacher-derived pseudo-labels beat placeholder labels by +0.118 Dice, showing that pseudo-label scale helps only when the teacher observes the correct modality.
Publications & Manuscripts
- X. Zhang, X. Wang, M. Xie, H. Liang, H. E. Lien, O. Das, J. Feghali, R. Xu, P. Liu. “Evaluation Principles for MRI–MRA Registration in Trigeminal Neuralgia: An ROI-Centered Neurovascular Benchmark.” IEEE Transactions on Medical Imaging, under review, 2026.
- X. Zhang. “Trajectory of Mobile Grasping Robot in Reinforcement Learning Application.” China Science and Technology, ISSN 1671-2064; CN11-4650/N, Jul 2024.
Selected Projects
Fine-Tuning LLMs on a Traditional Chinese Medicine Corpus
Team Lead · 5 members- Curated a domain-specific Traditional Chinese Medicine corpus and fine-tuned LLaMA, Mistral, and Phi to study how general-purpose LLMs adapt to specialized medical language, evaluated by perplexity, accuracy, and BLEU.
Human Action Prediction from Skeletons
UC Davis- Built a temporal model forecasting 5 future skeleton frames from 30 prior frames, with a custom pipeline to extract and align pose keypoints across a large video dataset.
Academic Service
Organizing Committee — FOMO26: Foundation Model Challenge for Brain MRI
MICCAI 2026- Co-led evaluation for Task 4 (Trigeminal Neuralgia Segmentation): multiclass segmentation of the trigeminal nerve and surrounding vasculature from T2-weighted MRI, scored by DSC and NSD.
Technical Skills
Programming
Python (PyTorch, TensorFlow, NumPy, SciPy, pandas, scikit-learn), C++, C, Java, SQL, JavaScript
Medical Imaging
ANTs, FireANTs, ConvexAdam, SynthMorph, EasyReg, VesselFM, nnU-Net; DICOM/NIfTI, 3D registration and segmentation, ROI-based evaluation
Tools & Statistics
Linux/Bash, Git, Conda, Jupyter; bootstrap CIs, Wilcoxon signed-rank, Spearman correlation