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Case Reports
. 2018 Apr 4;10(4):e2422.
doi: 10.7759/cureus.2422.

A New Era of Image Guidance with Magnetic Resonance-guided Radiation Therapy for Abdominal and Thoracic Malignancies

Kathryn Mittauer  1 , Bhudatt Paliwal  1 , Patrick Hill  1 , John E Bayouth  1 , Mark W Geurts  1 , Andrew M Baschnagel  1 , Kristin A Bradley  1 , Paul M Harari  1 , Stephen Rosenberg  1 , Jeffrey V Brower  2 , Andrzej P Wojcieszynski  3 , Craig Hullett  1 , R A Bayliss  1 , Zacariah E Labby  1 , Michael F Bassetti  1
Affiliations
Case Reports

A New Era of Image Guidance with Magnetic Resonance-guided Radiation Therapy for Abdominal and Thoracic Malignancies

Kathryn Mittauer et al. Cureus. .

Abstract

Magnetic resonance-guided radiation therapy (MRgRT) offers advantages for image guidance for radiotherapy treatments as compared to conventional computed tomography (CT)-based modalities. The superior soft tissue contrast of magnetic resonance (MR) enables an improved visualization of the gross tumor and adjacent normal tissues in the treatment of abdominal and thoracic malignancies. Online adaptive capabilities, coupled with advanced motion management of real-time tracking of the tumor, directly allow for high-precision inter-/intrafraction localization. The primary aim of this case series is to describe MR-based interventions for localizing targets not well-visualized with conventional image-guided technologies. The abdominal and thoracic sites of the lung, kidney, liver, and gastric targets are described to illustrate the technological advancement of MR-guidance in radiotherapy.

Keywords: gated tracking; mr guided radiotherapy; mri-guided adaptive radiotherapy; on-line adaptive radiotherapy; real-time tracking.

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Conflict of interest statement

The authors have declared financial relationships, which are detailed in the next section.

Figures

Figure 1
Figure 1. Clinical MRgRT workflow with workflow details unique to gating denoted in dotted outline and online adaptive in dashed outline.
MR-guided radiation therapy (MRgRT); CT: computed tomography; MR: magnetic resonance; QA: quality assurance; MIBH: maximum inspiration breath-hold
Figure 2
Figure 2. CBCT (left) and MRgRT scan (right). CBCT auto-match would have led to misalignment of GTV due to excessive noise of CBCT.
CBCT: cone-beam computed tomography; MRgRT: magnetic resonance-guided radiotherapy; GTV: gross target volume
Figure 3
Figure 3. Real-time tracking of 0.89 cm3 gross target volume with 5.0 mm boundary was feasible on clinical magnetic resonance-guided radiotherapy system, minimizing potential geometric miss observed from auto-match of cone-beam computed tomography-based registration for patient.
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Figure 4
Figure 4. Treatment plan for stereotactic body radiation therapy to the kidney (left). Treatment delivery magnetic resonance cine frame with real-time tracking of kidney at four frames per second to gate treatment beam on/off (right).
Figure 5
Figure 5. Pre-treatment PET (left) and post-treatment PET (right) for stereotactic body radiation therapy to the kidney treated on MRIdian system.
PET: positron emission tomography
Figure 6
Figure 6. GTV localized with CBCT (left) and MRIdian MRgRT setup scan (right) for fraction 2 and fraction 1, respectively, for patients undergoing liver stereotactic body radiation therapy for hepatocellular carcinoma.
GTV: gross target volume; CBCT: cone-beam CT; MRgRT: magnetic resonance-guided radiation therapy
Figure 7
Figure 7. Direct visualization of hepatocellular carcinoma in MR-gated delivery. Beam off (left) during tumor out of treatment field, and beam on (right) during tumor within the treatment field at breath-hold.
MR: magnetic resonance
Figure 8
Figure 8. Large inter-fraction stomach deformation between magnetic resonance simulation to fraction 9, for the case with the patient compliant with no eating or drinking four hours to radiotherapy.
Figure 9
Figure 9. Initial plan based on simulation magnetic resonance scan (left) and magnetic resonance-guided adapted plan (right) for fraction 9 for gastric lymphoma.
See this image and copyright information in PMC

References

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