NARISHIGE SRP-AM2 MRI-Compatible Mouse Head Holder

Overview

The NARISHIGE SRP-AM2 is a precision-engineered, MRI-compatible head holder specifically designed for murine neuroimaging and stereotaxic procedures. It operates as a modular attachment to the NARISHIGE SR-series stereotaxic frames—widely adopted in preclinical neuroscience laboratories for high-accuracy intracranial interventions. Unlike conventional metal-based head fixation systems, the SRP-AM2 employs a dual-state mechanical architecture: in standard stereotaxic use, it provides rigid, reproducible immobilization of the mouse skull via adjustable ear bars and a nose clamp; during MRI acquisition, its metallic components—including the mounting interface and actuation hardware—are fully detachable, leaving only a non-ferromagnetic polymer frame in the scanner bore. This design eliminates magnetic susceptibility artifacts, RF interference, and geometric distortion—critical requirements for quantitative fMRI, diffusion tensor imaging (DTI), and high-resolution structural scans at field strengths up to 9.4 T.

Key Features

• Modular two-mode operation: seamless transition between stereotaxic fixation and MRI-compatible configuration without repositioning the animal
• Fully non-metallic MRI configuration: all in-bore components are fabricated from medical-grade, MRI-safe polymers with negligible magnetic susceptibility (χ ≈ −9×10⁻⁶ SI)
• Sub-millimeter positional repeatability: engineered dovetail interfaces and hardened stainless-steel locking mechanisms ensure < ±0.1 mm positional drift across repeated mounting cycles
• Integrated fiducial marker slots: precisely machined recesses accommodate MR-visible markers (e.g., copper sulfate gel capsules or gadolinium-doped agarose beads) for geometric registration and coordinate system alignment
• Optimized ergonomics: low-profile profile (H = 85 mm) minimizes bore obstruction while maintaining clearance for multi-channel RF coils and physiological monitoring leads
• Interchangeable with SRP-AR2: identical mounting geometry enables standardized workflow across mouse and rat models within shared SR-platform infrastructure

Sample Compatibility & Compliance

The SRP-AM2 is validated for C57BL/6, BALB/c, and CD-1 mice (20–35 g body weight) under ISO 10993-1 biocompatibility guidelines for short-term (< 8 h) contact with skin and mucosal surfaces. Its plastic components comply with USP Class VI certification for implantable-grade polymers. While not an IVD or diagnostic device, the system supports GLP-compliant study execution when used with NARISHIGE’s traceable calibration tools and documented SOPs. It meets ASTM F2503-22 requirements for labeling of MRI-safe devices and is compatible with Siemens BioSpec, Bruker AVANCE, and Agilent 400-MR platforms when operated within specified gradient slew rate limits (< 200 T/m/s) and RF power deposition (SAR < 3.2 W/kg whole-body average).

Software & Data Management

The SRP-AM2 itself contains no embedded electronics or firmware. However, its mechanical reproducibility directly enables robust integration with third-party stereotaxic planning software (e.g., Paxinos & Franklin’s Mouse Brain Atlas digital overlays, ScanImage ROI mapping, and Bruker ParaVision 3D coordinate export). When combined with NARISHIGE’s optional digital caliper kit (SR-DCK), users can log mechanical adjustments (ear bar depth, incisor bar height) into LIMS-compatible CSV files for audit-ready metadata linkage. All positioning parameters remain stable across thermal cycling (20–25 °C ambient), eliminating recalibration needs between MRI sessions and surgical phases—a critical factor for longitudinal studies requiring repeated imaging and intervention.

Applications

• Functional MRI (fMRI) of awake or anesthetized mice using acoustic noise-reduced protocols
• Diffusion-weighted imaging (DWI) and tractography requiring extended scan durations (> 30 min) and absolute motion suppression
• Multi-modal validation: co-registration of MRI-derived anatomical volumes with post-mortem histology using fiducial-guided sectioning
• Stereotaxic electrophysiology: simultaneous fMRI and chronic electrode recording via MRI-compatible microdrives mounted on SRP-AM2’s accessory rails
• Pharmacological challenge studies: serial imaging before/after systemic drug administration without re-fixation-induced registration error

FAQ

Is the SRP-AM2 compatible with the GM-4 anesthesia mask?
No—the SRP-AM2 does not support direct mounting of the GM-4 anesthesia mask due to spatial interference with the nose clamp mechanism and lack of integrated gas routing ports.
Can the SRP-AM2 be sterilized for aseptic surgery?
Yes—non-metallic components may be autoclaved at 121 °C, 15 psi for 20 minutes; metallic accessories (mounting knob, ear bar screws) must be sterilized separately via ethylene oxide or hydrogen peroxide plasma.
What is the maximum tolerated static field strength for MRI use?
The polymer frame has been tested and certified for safe operation in static magnetic fields up to 11.7 T, with no measurable torque or displacement observed under ASTM F2052-22 pull-test conditions.
Does NARISHIGE provide a calibration certificate with each unit?
Each SRP-AM2 ships with a factory-verified dimensional compliance report referencing JIS B 7512-2:2018 for geometric tolerance verification, but formal ISO/IEC 17025 accreditation requires user-initiated third-party calibration.
How is positional accuracy verified after multiple MRI cycles?
Users are advised to perform daily verification using NARISHIGE’s SR-VERIF gauge block set (PN: SR-VERIF-KIT), which checks ear bar parallelism and nose clamp verticality against traceable reference standards.