Caption — GRE T1-weighted (1.5T, TR=5ms, FA=12°): The Mz panel is zoomed to the steady-state region (0.75–1.0 range) to make the small but real T1-driven differences visible. With TR=5ms, all tissues are heavily T1-saturated: fat (T1=260ms, shortest) reaches Mss≈0.905; WM (T1=650ms) reaches Mss≈0.963; CSF (T1=3600ms, longest) is most saturated at Mss≈0.991. Within each TR, fat drops the most after α (largest ΔMz), then recovers most before the next pulse — this repeated cycle produces fat having the highest Mxy·sinα = highest signal. The Mxy panel shows actual signal amplitude at TE=2ms: fat signal ≈ Mss·sin(12°)·exp(−2/T2*) — clearly the brightest tissue. CSF, despite long T2*, contributes very little because its Mss is lowest. This is the basis of T1 contrast in VIBE/LAVA/THRIVE liver acquisitions.

Caption — GRE T2*-weighted (1.5T, TR=50ms, FA=20°): With TR=50ms, the Mz excursions are much larger and clearly visible — fat drops from ~0.35 Mss to ~0.33 and recovers visibly within each TR. At TE=30ms, T2* decay strongly separates tissues: muscle (T2*=25ms) → only 30% of starting Mxy remains; GM (T2*=60ms) → 61%; WM (T2*=70ms) → 65%; fat (T2*=40ms) → 47%; CSF (T2*=1500ms) → 98%. Result: CSF dominates, muscle is dark, WM and GM are intermediate. Any iron, haemosiderin, or susceptibility source shortens local T2* further → appears as dark lesion against this background.

Caption — GRE T1-weighted at 3T (TR=5ms, FA=10°): At 3T, T1 values are longer. Fat at 3T has T1=380ms (vs 260ms at 1.5T) → less recovery per TR → Mss(fat at 3T) ≈ 0.944 vs 0.905 at 1.5T. All tissues are closer to M₀ (less saturated) but also closer to each other — the spread of Mss values is smaller, meaning less T1 contrast. FA=10° (vs 12° at 1.5T) is used because the Ernst angle shifts to smaller values when T1 is longer. The actual signal difference between fat and CSF at TE=2ms is slightly smaller at 3T than at 1.5T for the same TR — partially compensated by the higher intrinsic SNR at 3T. Gadolinium enhancement is less affected because Gd shortens T1 dramatically regardless of starting T1.

Caption — GRE T2*-weighted at 3T (TR=40ms, TE=20ms): At 3T, T2* values are shorter (~20–30% shorter than at 1.5T) because the susceptibility effect scales with B0. At TE=20ms: muscle (T2*=20ms) → 37% remaining; GM (T2*=45ms) → 64%; WM (T2*=55ms) → 69%; fat (T2*=28ms) → 49%; CSF (T2*=1200ms) → 98%. The ordering is the same as at 1.5T but achieved at shorter TE. Mz excursions are clearly visible in the upper panel. The practical implication: metallic implant susceptibility artefacts are ~4× larger in linear extent at 3T vs 1.5T for equivalent TE — always consider using 1.5T or reducing TE when imaging near metallic hardware.