What is a Savi Scout?
The Savi Scout is a wireless, non-radioactive, electromagnetic wave reflector device used for preoperative localization of non-palpable breast lesions, serving as an alternative to traditional wire-guided localization.
Device Description and Mechanism
The Savi Scout is a surgical guidance system that uses a small reflector implant (approximately 1.6 mm × 12 mm) that is percutaneously inserted adjacent to or within breast lesions under image guidance (mammographic or ultrasound) 1, 2. The reflector is activated intraoperatively by a handheld device that emits infrared light and electromagnetic waves, allowing the surgeon to precisely locate and excise the target lesion 2.
Clinical Performance
Deployment and Retrieval Success
- Deployment success rate: 99.64% across 842 cases in pooled analysis 3
- Retrieval success rate: 99.64% with 100% target excision in initial studies 2, 3
- Mean deployment time: 5.6-19 minutes depending on imaging modality 1, 4
- Mean target-to-reflector distance: 0.3-0.6 mm, demonstrating high accuracy 1, 2
Surgical Outcomes
- Re-excision rate: 5.3-7.4% for malignant lesions with positive margins 2, 5
- This compares favorably to wire localization re-excision rates of 13.7-21.1% (p<0.01) 3, 5
- The device can be placed 0-8 days before surgery, decoupling radiology and surgical scheduling 2
- Multiple reflectors can be placed as close as 2.6 cm apart for bracketing multiple lesions 2
Advantages Over Wire Localization
Operational Efficiency
- Reduced perioperative time: 381 minutes for Savi Scout vs 469 minutes for wire localization in hospital settings (p≤0.001) 4
- Decreased OR delays: Average delay of 53 minutes vs 85 minutes for wire localization (p<0.001) 4
- Flexible scheduling eliminates same-day coordination requirements between radiology and surgery 3, 4
Clinical Safety
- Lower complication rate: 2.1% surgical site occurrences vs 7.4% with wire localization 5
- Migration rate: 0-4.5%, typically associated with hematoma formation 1, 2
- No radiation exposure, unlike radioactive seed localization 1, 3
Important Caveats
Migration risk: While rare (0-4.5%), reflector migration can occur, particularly in the presence of hematomas 1, 2. Five cases in one series showed increased target-to-reflector distance >1.0 cm on specimen radiography 2.
Learning curve: Initial deployment times may be longer (19 minutes) compared to wire localization (15 minutes), though this improves with experience 4.
Verification required: Specimen radiography remains essential to confirm both target and reflector removal 2.
Patient and Physician Acceptance
Both radiologists and surgeons rated the Savi Scout technique as superior to wire-guided localization, with high patient satisfaction scores across multiple studies 1, 3. The elimination of protruding wires and flexible scheduling are particularly valued by patients 1, 5.