MRI & CT Scanner Cable Assemblies

MRI, CT, and PET scanners each impose unique and extreme demands on cable assemblies — demands fundamentally different from other medical imaging cables.

MRI generates 1.5–7 Tesla magnetic fields plus radiofrequency pulses at 64–300 MHz. Any ferromagnetic material becomes a projectile hazard. Any long conductor in the bore acts as an antenna, heating tissue at the cable tip. Cable design must eliminate all ferromagnetic metals and prevent RF-induced heating through segmented shield topology.

CT scanners rotate the gantry at 0.27–0.5 seconds per revolution — continuously, 24/7, for the scanner's 10+ year service life. Cables connecting rotating components to stationary electronics must survive 5–10 million torsional cycles without impedance drift or conductor fatigue.

PET detectors require ultra-low-noise signal cables with shielding effectiveness exceeding 85 dB at 100 MHz to extract weak scintillation signals from a high-EMI environment inside the scanner bore.

We manufacture specialized cable assemblies for all three modalities, addressing the specific material, mechanical, and electromagnetic requirements of each.

MRI-Compatible Cable Assemblies

Projectile Safety — Zero Ferromagnetic Materials
Every metal component in the cable must be non-ferromagnetic — not just "low-magnetic" but genuinely non-ferromagnetic per ASTM F2052 (deflection angle < 45° at scanner entrance). This eliminates: nickel, iron, cobalt, nickel-plated contacts, stainless steel braid (which becomes ferromagnetic after cold-working), zinc-plated steel hardware.

Acceptable materials:

SAR Heating Prevention — Segmented Shield Topology
Eliminating ferromagnetic metals prevents the projectile hazard but does not prevent RF-induced tissue heating. Long cables in the MRI bore act as antennas at the Larmor frequency (64 MHz at 1.5T, 128 MHz at 3T, 298 MHz at 7T). A resonant cable can heat tissue at the cable tip by 5–10°C — clinically dangerous.

Our design uses segmented shield topology: the cable shield is interrupted at lambda/4 intervals (approximately 7–8 cm at 3T/128 MHz) by RF choke elements (high-impedance ferrite beads or resonant traps). This prevents the cable from acting as a half-wave or full-wave antenna at the Larmor frequency, limiting induced current and tip heating.

SAR testing: Performed per IEC 60601-2-33 Annex EE in ASTM tissue-equivalent phantom. We report maximum local SAR (W/kg) at the cable tip under worst-case cable positioning (parallel to B0, centered in bore). Compliance threshold: per customer specification or IEC 60601-2-33 normal mode limit.

MRI Field Strength Compatibility:

Standard production covers 1.5T and 3T (the vast majority of clinical MRI installations worldwide). 7T requires custom engineering of shield segmentation spacing and is quoted on a per-project basis.

CT Scanner Gantry Cables

CT gantry cables connect rotating scanner components (X-ray tube, detector array, data acquisition system) to stationary electronics via slip rings or wireless data links. The defining requirement: continuous ±360° rotation at sub-second revolution speed for the scanner's entire service life.

CT gantry cable design shares the counter-helical construction principles of surgical robot cables (see Robotic Surgery Application page) but at larger scale and higher cycle counts. The primary engineering challenge is maintaining signal integrity at multi-gigabit data rates while the cable undergoes continuous rotational deformation.

PET Detector Cables

ET (Positron Emission Tomography) scanners detect 511 keV annihilation photon pairs using scintillation crystal + photodetector arrays arranged in a ring around the patient. Signal cables connecting detector modules to coincidence counting electronics must provide:

Ultra-low noise: PET scintillation signals are weak (< 1 mV). Cable-induced noise must be minimized through shielding effectiveness > 85 dB at 100 MHz.

High shielding: Double-shield construction (foil + double braid) achieving > 85 dB shielding effectiveness, compared to ~40 dB for standard single-shield micro coax.

Timing precision: Coincidence timing window in modern TOF-PET is 200–400 ps. Cable propagation delay variation must be controlled to avoid timing jitter.

Cable spec: 42 AWG, ePTFE dielectric, foil + double Ag-plated Cu braid (> 85 dB), phase-matched for timing-critical channels, PFA jacket. Connector: typically MMCX or custom high-density.

Specifications Summary — MRI, CT, PET

Frequently Asked Questions

What MRI field strengths are supported?

Standard production: MR Conditional at 1.5T and 3T, covering the vast majority of clinical installations. Shield segmentation is tuned for 64 MHz (1.5T) and 128 MHz (3T) Larmor frequencies. 7T requires custom shield segment engineering with 8–12 week development cycle.

Can changing just the connector make a cable MRI-compatible?

Connector replacement addresses the projectile hazard (by eliminating ferromagnetic connector materials) but does not address SAR heating. For cables shorter than 10 cm that remain entirely outside the MRI bore, a connector swap may be sufficient. For cables longer than 15 cm that route inside the bore, segmented shielding and SAR testing are also required. The rule of thumb: if the cable is long enough to act as an antenna at the Larmor frequency, it needs segmented shielding.

What SAR testing documentation do you provide?

SAR test report per IEC 60601-2-33 Annex EE methodology, including: test setup (phantom composition, cable position, field strength), measured local SAR at cable tip (W/kg), comparison to applicable limits, and pass/fail determination. Testing is performed at an accredited MRI safety testing laboratory.

Can the same cable work in both 1.5T and 3T?

Not optimally. Shield segmentation spacing is tuned to a specific Larmor frequency. A cable optimized for 3T (128 MHz, ~8 cm segments) will not be optimal at 1.5T (64 MHz, ~25 cm segments). For multi-field-strength compatibility, we can design a dual-tuned segmentation pattern, but this is a custom engineering project.

How many torsional cycles does a CT cable actually need?

A busy CT scanner performs approximately 50–100 scans per day, each scan involving 10–30 gantry rotations. That is approximately 500–3,000 rotations per day, or 180,000–1,100,000 per year. Over a 10-year scanner service life: 1.8–11 million total rotations. Our standard specification of 5M cycles covers the majority of installations; 10M premium specification covers high-utilization hospital scanners.

Do you supply cables for Siemens, GE, or Philips MRI/CT systems?

We supply cable assemblies to MRI and CT OEMs and third-party component developers. We do not supply replacement cables for specific scanner models from Siemens, GE, or Philips. Our customers are companies designing new scanner components, RF coils, or detector modules that require MRI-safe or CT-rated cable assemblies.

Designing cables for MRI, CT, or PET? Share modality, field strength (MRI) or rotation spec (CT), cable routing, and signal requirements — we will outline the optimal material selection and testing pathway.

Get A Quote Now

Related Words: MRI CT scanner cable, MRI compatible cable assembly, CT scanner cable assembly, MRI safe coaxial cable, non-magnetic cable manufacturer, MRI coil cable, titanium connector MRI, CT gantry cable, PET detector cable, non-ferromagnetic cable, MRI conditional cable