Find in Library

High-frequency repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex (L-DLPFC) shows promise as a treatment for treatment-resistant depression in adolescents. Conventional rTMS coil placement strategies include the 5 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>cm</mi></semantics></math></inline-formula>, the Beam F3, and the magnetic resonance imaging (MRI) neuronavigation methods. The purpose of this study was to use electric field (E-field) models to compare the three targeting approaches to a computational E-field optimization coil placement method in depressed adolescents. Ten depressed adolescents (4 females, age: <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>15.9</mn><mo>±</mo><mn>1.1</mn></mrow></semantics></math></inline-formula>) participated in an open-label rTMS treatment study and were offered MRI-guided rTMS five times per week over 6–8 weeks. Head models were generated based on individual MRI images, and E-fields were simulated for the four targeting approaches. Results showed a significant difference in the induced E-fields at the L-DLPFC between the four targeting methods (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>χ</mi><mn>2</mn></msup><mo>=</mo><mn>24.7</mn></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo><</mo><mn>0.001</mn></mrow></semantics></math></inline-formula>). Post hoc pairwise comparisons showed that there was a significant difference between any two of the targeting methods (Holm adjusted <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo><</mo><mn>0.05</mn></mrow></semantics></math></inline-formula>), with the 5 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>cm</mi></semantics></math></inline-formula> rule producing the weakest E-field (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>46.0</mn><mo>±</mo><mn>17.4</mn><mspace width="0.166667em"></mspace><mi mathvariant="normal">V</mi><mo>/</mo><mi mathvariant="normal">m</mi></mrow></semantics></math></inline-formula>), followed by the F3 method (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>87.4</mn><mo>±</mo><mn>35.4</mn><mspace width="0.166667em"></mspace><mi mathvariant="normal">V</mi><mo>/</mo><mi mathvariant="normal">m</mi></mrow></semantics></math></inline-formula>), followed by MRI-guided (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>112.1</mn><mo>±</mo><mn>14.6</mn><mspace width="0.166667em"></mspace><mi mathvariant="normal">V</mi><mo>/</mo><mi mathvariant="normal">m</mi></mrow></semantics></math></inline-formula>), and followed by the computational approach (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>130.1</mn><mo>±</mo><mn>18.1</mn><mspace width="0.166667em"></mspace><mi mathvariant="normal">V</mi><mo>/</mo><mi mathvariant="normal">m</mi></mrow></semantics></math></inline-formula>). Variance analysis showed that there was a significant difference in sample variance between the groups (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>K</mi><mn>2</mn></msup><mo>=</mo><mn>8.0</mn></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo><</mo><mn>0.05</mn></mrow></semantics></math></inline-formula>), with F3 having the largest variance. Participants who completed the full course of treatment had median E-fields correlated with depression symptom improvement (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>r</mi><mo>=</mo><mo>−</mo><mn>0.77</mn></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo><</mo><mn>0.05</mn></mrow></semantics></math></inline-formula>). E-field models revealed limitations of scalp-based methods compared to MRI guidance, suggesting computational optimization could enhance dose delivery to the target.