William J Brown, MS1, Maria A Cassera, BS2, Zeljka Jutric, MD2, Paul D Hansen, MD2, Chet W Hammill, MD, MS, MCR2. 1Meharry Medical College, 2Providence Cancer Center
Introduction:
Precise needle placement within the liver is essential during hepatic ablation procedures.Tumor targeting is typically performed under ultrasound guidance, however, this can be challenging. A novel 3-D guidance system, has been developed to aid in accurate needle placement during ablation.
Methods:
Five novices and five experienced hepatobiliary surgeons were recruited for participation. Using an agar block with a strategically placed analog tumor, participants targeted the tumor under four controlled conditions: in-line with the ultrasound plane (0 degrees off-axis) using ultrasound alone, in-line with the ultrasound plane using 3-D guidance, off-axis to the ultrasound plane (45 degrees off-axis) using ultrasound alone, and off-axis to the ultrasound plane using 3-D guidance. Time to target the tumor, the number of withdrawals required to accurately target the center of the tumor, and the National Aeronautics and Space Administration Task Load Index (NASA-TLX) were collected. The NASA-TLX is an established tool for measurement of mental workload.Initial and final parameters for each of the four conditions were compared using a within-subjects paired t-test.
Results:
Results for mean time to target tumor, mean number of withdrawals, and mean NASA-TLX score are reported in Table 1. A significant reduction was seen in the number of required withdrawals in all situations when using the 3-D guidance. Mental workload was similar initially, but was significantly lower using 3-D guidance after proficiency was achieved. The only difference in targeting time was in the initial trials when approaching the target from 45 degrees off-axis.
Conclusion:
Although 3-D guidance did not reduce targeting time substantially, it did reduce the number of required withdrawals, potentially decreasing complications and decreased mental workload after proficiency was achieved.
| In Line (0 degrees off-axis) | First Trial | p-value | Last Trial | p-value |
|
Mean Time(seconds): Ultrasound Guidance 3-D Guidance |
117.4 71.2 |
0.234 |
93.5 55.8 |
0.412 |
|
Mean Number of Withdrawals: Ultrasound Guidance 3-D Guidance |
4.6 1.1 |
0.003 |
4.1 0.1 |
0.009 |
|
Mean Mental Workload Score: Ultrasound Guidance 3-D Guidance |
48.7 42.7 |
0.213 |
47.3 24.3 |
0.017 |
| Out of Line (45 degrees off-axis) | First Trial | p-value | Last Trial | p-value |
|
Mean Time(seconds): Ultrasound Guidance 3-D Guidance |
82.5 31.2 |
0.031 |
129.2 17.8 |
0.158 |
|
Mean Number of Withdrawals: Ultrasound Guidance 3-D Guidance |
2.2 0.6 |
0.003 |
5.9 0.1 |
0.009 |
|
Mean Mental Workload Score: Ultrasound Guidance 3-D Guidance |
48.6 34.5 |
0.054 |
49.3 20.4 |
0.0002 |