Does MR imaging give us advantage in contouring thoracic structures for Cardiac SABR?
|dc.contributor.author||Aznar, Marianne Camille|
|dc.identifier.citation||Fuertes L, Dubec M, Anjanappa M, Rodgers J, Hales R, Clough A, et al. PO-1020: Does MR imaging give us advantage in contouring thoracic structures for Cardiac SABR? Radiotherapy and Oncology . 2020 Nov;152:S544–5.||en|
|dc.description.abstract||Purpose or Objective Cardiac magnetic resonance is the gold-standard imaging technology for identifying scars, the most common cause of ventricular tachycardia (VT) in patients with previous history of myocardial infarction. Recent studies have shown promising results for cardiac SABR ablation of refractory VT. As MR-guided RT (e.g. as delivered on an MR-linac) develops, daily full online replanning guided by MR is becoming a reality. Here, we analyze differences between CT and MR contouring of thoracic structures routinely contoured for cardiac SABR. Material and Methods We chose three patients from an institutional lung cancer database. Each patient had a set of diagnostic MR images (T1 with fat saturation, a sequence we can acquire with the MR-linac), a planning CT and a CBCT. We ask five observers (three radiographers and two clinicians) to contour two thoracic structures (heart and esophagus) on the three sets of images of the three patients (figure 1). The volunteers used a five-point visual grading scale (1 = very unconfident, 2 = unconfident; 3 = confident with reservations, 4 = confident, 5 = very confident) to indicate their confidence when contouring Results The mean confidence for the heart contours (n=15) in the MR, planning CT and CBCT images was 4.33±0.49, 4.27±0.59 and 2,33±0.46, respectively, and for the esophagus contours (n=15) was 4.07±0.8, 3.8±0.68 and 1.33±0.49, respectively. The grade of confidence in contouring heart and esophagus was significatively higher with MR than with CBCT (p<0.01 in both cases). No statistically significant differences were observed between MR and planning CT contours. Conclusion These results highlight the limitation of CBCT images for daily online replanning in thoracic tumours. Though our results need to be validated with on-board MR-images, they suggest that there could be clear advantages to using daily MR-guided radiotherapy for cardiac SABR, where precise delivery of radiotherapy would result in optimal dose whilst minimising risk of complications. Further investigation is needed to determine the best MR sequences required for daily MR-based adaptive replanning for cardiac SABR.||en|
|dc.title||Does MR imaging give us advantage in contouring thoracic structures for Cardiac SABR?||en|
|dc.type||Meetings and Proceedings||en|
|dc.contributor.department||Hospital Universitario La Paz, Radiation Oncology, Madrid,||en|
|dc.identifier.journal||Radiotherapy and Oncology||en|