Table 1 Guidewire configurations tested during in vitro experiments. Experiments were performed in the ASTM-2182 phantom using Terumo Glidewires and Medtronic Nitrex in a 70 cm bore 1.5 T MRI system (Aera, Siemens, Erlangen, Germany)
Property | Experimental details | Maximum Heating Condition |
|---|---|---|
Catheter insulation | • Heating at guidewire tip and catheter tip were measured simultaneously • Guidewire position relative to catheter: 10 cm, 5 cm, 2 cm, 1 cm (guidewire extended), 0 cm (tips aligned), − 2 cm, − 5 cm (guidewire retracted inside catheter). | • 1 cm guidewire extension; the change in insulation is similar to that of an exposed metallic tip. |
Guidewire Length | • Terumo Glidewires of lengths 150 cm, 180 cm and 260 cm with catheter insulation (1 cm exposed guidewire) | • 260 cm guidewire for Terumo Glidewires |
Guidewire position | • The temperature distribution of this phantom with this CMR system has been mapped previously [17] | • Positioned near the edge of the bore (> 12 cm off-isocenter) and near the surface of the gel (> 5 cm depth). |
Insertion length | • Insertion lengths 15-65 cm into the ASTM gel phantom were tested for the three lengths of Terumo Glidewire with catheter insulation (1 cm exposed guidewire) | • 45 cm–55 cm insertion length for all guidewire lengths. |
Looping | • Loops were created in segments of bare wire, as is common in the body, in the coronal plane • Loop diameter = 5 cm and single, double, triple and quadruple loops were compared. • Temperature was measured both at the tip of the guidewire and the contact point of the loops, where a second hotspot is formed. | • Temperature was always higher at the guidewire tip compared to the loop contact point and temperature in both locations increased with increasing number of loops. • Using the bare wire with no catheter insulation, generates lower temperatures and looping was not investigated further |