Evaluation of the effects of motion mitigation strategies on respiration‐induced motion in each pancreatic region using cine‐magnetic resonance imaging

Abstract

Purpose This study aimed to quantify the respiration‐induced motion in each pancreatic region during motion mitigation strategies and to characterize the correlations between this motion and that of the surrogate signals in cine‐magnetic resonance imaging (MRI). We also aimed to evaluate the effects of these motion mitigation strategies in each pancreatic region. Methods Sagittal and coronal two‐dimensional cine‐MR images were obtained in 11 healthy volunteers, eight of whom also underwent imaging with abdominal compression (AC). For each pancreatic region, the magnitude of pancreatic motion with and without motion mitigation and the positional error between the actual and predicted pancreas motion based on surrogate signals were evaluated. Results The magnitude of pancreatic motion with and without AC in the left–right (LR) and superior–inferior (SI) directions varied depending on the pancreatic region. In respiratory gating (RG) assessments based on a surrogate signal, although the correlation was reasonable, the positional error was large in the pancreatic tail region. Furthermore, motion mitigation in the anterior‐posterior and SI directions with RG was more effective than was that with AC in the head region. Conclusions This study revealed pancreatic region‐dependent variations in respiration‐induced motion and their effects on motion mitigation outcomes during AC or RG. The magnitude of pancreatic motion with or without AC and the magnitude of the positional error with RG varied depending on the pancreatic region. Therefore, during radiation therapy for pancreatic cancer, it is important to consider that the effects of motion mitigation during AC or RG may differ depending on the pancreatic region.

Dosimetric Feasibility Study of Dose Escalated Stereotactic Body Radiation Therapy (SBRT) in Locally Advanced Pancreatic Cancer (LAPC) Patients: It Is Time to Raise the Bar

“…As a whole, these results suggest that respiratory gating and breath hold may be the best choice for organ motion management in pancreatic SBRT, in particular if a dose escalated approach is planned. Nevertheless, pancreatic region‐dependent variations in respiratory induced organ motion, and their effects on motion control approach, have been described ( 24 ). In particular, motion mitigation techniques resulted less effective in the tail region, with no difference between the use of abdominal compression versus respiratory gating, probably due to the larger positional error in the tail region based on the abdominal wall surrogate.…”

Dosimetric impact of intrafraction motion under abdominal compression during MR-guided SBRT for (Peri-) pancreatic tumors

“…Moreover, these methods might not be readily available on all systems. Passive motion mitigation through abdominal compression has shown to be a simpler, more accessible alternative for both pancreatic tumors (Lovelock et For pancreatic tumors, abdominal compression with an abdominal corset can significantly reduce cranio-caudal tumor motion during treatment to around 5 mm (Lovelock et al 2014, Campbell et al 2017, Heerkens et al 2017, Dolde et al 2019, Fujimoto et al 2019. This results in respiratory intrafraction tumor motion that is small and stable between treatment fractions (Grimbergen et al 2022).…”

Advancing the frontiers of MR-guided radiotherapy for pancreatic cancer

“…80,91 Moreover, these methods might not be readily available on all systems. Passive motion mitigation through abdominal compression has shown to be a simpler, more accessible alternative for both pancreatic tumors 33,61,66,[92][93][94][95] as well as liver tumors. [96][97][98][99] For pancreatic tumors, abdominal compression with an abdominal corset can significantly reduce cranio-caudal tumor motion during treatment to around 5 mm.…”

“…[96][97][98][99] For pancreatic tumors, abdominal compression with an abdominal corset can significantly reduce cranio-caudal tumor motion during treatment to around 5 mm. 33,[92][93][94][95] This results in respiratory intrafraction tumor motion that is small and stable between treatment fractions. 61 However, because of the close proximity of upper abdominal tumors to abutting organs at risk (OAR), the exact impact of the residual intrafraction motion on the delivered dose remains of concern.…”