GE Discovery MI
Manufacturer: GE HealthCare · Modality: PET/CT
Digital PET/CT — replaces photomultiplier tubes with silicon photomultipliers (SiPM). Succeeds the Discovery 690 in the GE PET/CT lineup. SiPM's compact size, magnetic-field tolerance, and direct-digital readout enable smaller pixel sizes, faster ToF timing, and higher sensitivity than the PMT-based 690.
What changed vs Discovery 690
- SiPM detectors replace photomultiplier tubes. One-to-one per LYSO crystal pixel (vs PMT reading a 9×6 or similar crystal block on the 690).
- Pixel size reduced (~4.0 × 5.3 × 25 mm LYSO on newer configurations)
- ToF timing improved (~375 ps on Discovery MI Gen 2 vs ~500 ps on the 690)
- Axial FOV configurable — 15 / 20 / 25 cm (the 690 was fixed)
- Reconstruction — Q.Clear BSREM iterative + DL Q.Clear
Clinical implications
Faster + sharper + more sensitive than the 690. Translates clinically to:
- Faster scan times (shorter bed positions) or lower injected dose at equivalent quality
- Smaller lesion detection (thanks to finer pixel + better ToF)
- Better cardiac PET (rubidium) image quality
Specs
- LYSO crystals · ~4 × 5.3 × 25 mm
- SiPM readout
- ToF timing ~375 ps (Gen 2)
- Axial FOV options 15 / 20 / 25 cm
- CT base — Revolution-generation CT (varies by configuration)
- Q.Clear + DLIR reconstruction
- Ge-68 rod source calibration (same as 690)
Cross-platform comparisons
- Siemens Biograph Vision — SiPM competitor, ~214 ps ToF (newer Siemens TrueX electronics). Narrowest timing among contemporary clinical PET platforms.
- Philips Vereos — first commercial SiPM PET/CT, 320 ps ToF.
- Discovery 690 — Discovery MI's predecessor; still widely deployed. The MI is a generational upgrade, not a refresh.
Parts
CT-side parts shared with GE Revolution-generation CT platforms.
Service reality
SiPM modules are different failure mode than PMTs — drift patterns differ; replacement is at the module level. Tube + gantry + CT components share with GE Revolution-generation CT parts ecosystem.