{"artifact_id":"L1-056","layer":"L1","title":"Chemical Exchange Saturation Transfer (CEST) MRI","domain":"Medical Imaging","sub_domain":"Indirect detection of exchangeable metabolite protons","physics_fingerprint":{"L_DAG":3.8,"title":"Chemical Exchange Saturation Transfer (CEST) MRI","domain":"Medical Imaging","carrier":"radio_wave","primitives":["L.rf_excitation","L.saturation_rf_pulse","L.z_spectrum_fit","int.spectral"],"sub_domain":"Indirect detection of exchangeable metabolite protons","noise_model":"gaussian","problem_class":"nonlinear_inverse","solution_space":"3D_cest_spectrum","difficulty_delta":5,"integration_axis":"spectral","sensing_mechanism":"mri_chemical_exchange"},"observable_profile":{"metric":"PSNR_dB","regime":"Existence of the recovered 3D cest spectrum is guaranteed within the declared Omega bounds. Uniqueness is local rather than global (non-convex landscape); convergence depends on initialisation and priors. Stability is moderately conditioned (kappa_eff ~= 17); B0_inhomogeneity dominates the stability cliff; B1_inhomogeneity and the remaining mismatch parameters contribute higher-order bias terms. Additive gaussian thermal/electronic noise sets the irreducible data-fidelity floor, while TV / wavelet-sparsity / deep priors stabilise recovery at the ill-conditioned end of Omega.","secondary":"SSIM"},"size_tiers":{"center_spec":{"omega":{"H":128,"W":128,"Z":16,"B1_uT":2.0,"TR_ms":4000,"SNR_dB":20,"N_offsets":31,"B0_inhomogeneity":0.0,"B1_inhomogeneity":0.0,"MT_contamination":0.0,"direct_water_saturation":0.0},"input_format":"measurement_only","problem_class":"cest_mri","forward_operator":"cest_mri_forward","epsilon_fn_center":"16.0"},"omega_bounds":{"H":32,"W":32,"Z":[4,64],"B1_uT":[0.5,5.0],"TR_ms":[1000,10000],"SNR_dB":[0.0,35.0],"N_offsets":[10,101],"B0_inhomogeneity":[0.0,0.3],"B1_inhomogeneity":[0.0,0.3],"MT_contamination":[0.0,0.3],"direct_water_saturation":[0.0,0.3]},"epsilon_bounds":{"psnr_db":[5.0,45.0]},"allowed_problem_classes":["cest_mri"],"allowed_omega_dimensions":["H","W","Z","N_offsets","B1_uT","TR_ms","SNR_dB","B0_inhomogeneity","B1_inhomogeneity","direct_water_saturation","MT_contamination","B0_inhomogeneity","B1_inhomogeneity","direct_water_saturation","MT_contamination"],"allowed_forward_operators":["cest_mri_forward"]},"hardness_fn":{"type":"epsilon_fn","delta":5,"kappa":340,"metric":"PSNR_dB"},"initiator_dataset":[{"name":"primary","weight":1.0,"ipfs_cid":null,"license_hash":null}],"status":"testnet","staked_pwm":0.0,"chain_hash":"0x5f6ecefd3ad7a6cd4b0802388c37a29c9f5c2ce9d9406b654dc04ae4603b52b4","chain_tx_hash":"0xa732d6e582591baff493cc68415468e56fceb556a2fdbc3fc9b3f03a19a9a6ff","chain_block":41553386}