Impact of Image Latency and Frame Rate on Simulated Remote Robotic-Assisted Neurovascular Procedures

The implementation of remote procedures represents the ultimate goal of the robotic development in the neurovascular field. Studies from remote cardiac interventions established a maximum latency threshold of 400 ms, however, no data are available for neurovascular procedures. The aim of this study was to define the maximum acceptable latency and minimum refreshment frame rate (RFR) for neuroendovascular procedures in a simulated remote setting.

Using a virtual simulator and an endovascular robotic arm, 7 operators performed 8 simulated aneurysm and stroke treatment interventions (4 manually and 4 robotic-assisted), during which video display of the intervention was randomly altered with different latencies (100, 250, 450, 600, 800 ms) and RFR (10, 15, 25, 30 frames per second [fps]). Operators rated the acceptability of each latency and RFR by using a modified acceptability score (mAS) and an independent observer recorded the number of dangerous uncontrolled movement (DUMs).

Maximum acceptable latency (defined as a minimum mAS of 85%) was defined at 100 ms for manually performed procedures and at 250 ms by using robotic-assistance, whereas minimum acceptable RFR was defined at 15 fps. A total of 55 intracranial DUMs were recorded, most of which occurred at latencies ≥450 ms (49/51) and with RFRs of 10 fps (4/4). Time intervals were shorter for manual procedures, although not significantly, and for experienced operators.

Latency during simulated neurovascular interventions influences operator performance, judgment, and confidence and maximum thresholds (250 ms) seem to be lower than those previously reported from remote cardiac interventions. In this experimental setting, RFR seemed to have a lower impact in terms of acceptance rates. Latency and RFR represent relevant parameters to define and monitor in remote environments to maximize safety.