systemGE HealthCarePET MR

GE Signa PET/MR

Manufacturer: GE HealthCare · Modality: PET/MR

GE's 3 T PET/MR — the first commercial simultaneous PET/MR system with silicon-photomultiplier (SiPM) PET detectors and Time-of-Flight capability. Combines a whole-body 3 T MRI scanner (60 cm bore) with a SiPM PET ring inside the MR bore, enabling spatially and temporally co-registered PET and MR acquisition in a single exam — materially different from sequential PET/CT + MR workflows.

PET detector architecture

  • 45 LBS (lutetium-based scintillator) rings — 20,160 total crystals.
  • 28 SiPM modules — silicon photomultipliers replace traditional PMTs. Magnetic-field-immune (unlike PMTs), enabling the detector to operate inside the 3 T MR bore.
  • Axial FOV 25 cm — competitive with current digital PET/CT platforms.
  • Transaxial FOV 60 cm — matches the MR bore.
  • Sensitivity 21 cps/kBq — competitive with digital PET/CT class.
  • Time-of-Flight — <0.4 ns (400 ps) timing resolution, 4.57 ns coincidence window. Comparable to the contemporary digital PET/CT class.

MR architecture

  • 3 T field strength — whole-body diagnostic MR.
  • 60 cm bore — narrower than GE's current clinical 3 T Signa family (70 cm), a trade-off made to accommodate the PET detector ring inside the MR bore.
  • SIGNAWORKS host — current GE MR operating environment (QuantWorks branding for PET/MR-specific workflows).

MR-based attenuation correction

  • ZTE (Zero Echo Time) MR — the load-bearing attenuation-correction approach on Signa PET/MR. ZTE captures cortical bone signal (normally invisible on conventional MR) and derives an attenuation map without the ionizing-radiation CT attenuation scan that PET/CT uses.
  • Quant capabilities — QuantWorks enables standardized uptake value (SUV) quantification with MR-based attenuation correction that approaches CT-AC accuracy for most clinical use cases.

Simultaneous PET/MR — why it matters

  • Spatial co-registration — PET events and MR voxels share a common reference frame without the inter-exam misregistration that occurs between sequential PET/CT and MR.
  • Temporal co-registration — dynamic PET and dynamic MR acquired concurrently, enabling pharmacokinetic models that require matched timing.
  • Motion management — cardiac / respiratory gating signals from MR can drive PET reconstruction, reducing motion blur on small-lesion PET.
  • Ionizing-radiation reduction — no CT attenuation scan and no CT-for-localization, reducing cumulative dose for serial imaging (oncology follow-up, pediatric).

Specs

  • 3 T · 60 cm bore
  • 45 LBS rings · 20,160 crystals · 28 SiPM modules
  • Axial FOV 25 cm · transaxial FOV 60 cm
  • ToF <0.4 ns · coincidence 4.57 ns · sensitivity 21 cps/kBq
  • ZTE MR-based attenuation correction
  • QuantWorks PET/MR host

Clinical positioning

  • Neuro-oncology — glioma characterization, radiation-necrosis vs recurrence differentiation.
  • Pediatric oncology — dose reduction matters most in serial follow-up populations.
  • Prostate — PSMA PET + multiparametric prostate MR in a single exam.
  • Neurodegenerative imaging — amyloid / tau PET co-acquired with structural and functional MR.
  • Cardiac — sarcoidosis, infiltrative cardiomyopathy where PET and MR complement.
  • Gynecologic and head-and-neck oncology — soft-tissue contrast of MR with PET metabolic data.

Operational reality

  • NRC / state license for PET radiotracers; RSO oversight. See NRC licensing.
  • Helium and cold-head management per MRI service norms.
  • Siting — PET/MR combines MR site planning (5-gauss line, RF shielding, quench pipe) with radioactive-materials handling. Site preparation is substantial.
  • Throughput — exam times are longer than PET/CT; workflow design matters for economic viability.

Relationship to siblings

  • GE Signa family 3T MRIs — Signa Premier, Signa Pioneer share Signa lineage but are not PET/MR capable. Signa PET/MR is a distinct product with a purpose-built PET ring.
  • GE Discovery MI / Discovery 690 — PET/CT platforms in parallel to Signa PET/MR.

Related