Dataset Information

Comparison of four dimensional computed tomography and magnetic resonance imaging in abdominal radiotherapy planning.

ABSTRACT:

Background and purpose

Four-dimensional (4D) computed tomography (CT) is widely used in radiotherapy (RT) planning and remains the current standard for motion evaluation. We assess a 4D magnetic resonance imaging (MRI) sequence in terms of motion and image quality in a phantom, healthy volunteers and patients undergoing RT.

Materials and methods

The 4D-MRI sequence is a prototype T1-weighted 3D gradient echo with radial acquisition with self-gating. The accuracy of the 4D-MRI respiratory sorting based method was assessed using a MRI-CT compatible respiratory simulation phantom. In volunteers, abdominal viscera were evaluated for artefact, noise, structure delineation and overall image quality using a previously published four-point scoring system. In patients undergoing abdominal RT, the tumour (or a surrogate) was utilized to assess the range of motion on both 4D-CT and 4D-MRI. Furthermore, imaging quality was evaluated for both 4D-CT and 4D-MRI.

Results

In phantom studies 4D-MRI demonstrated amplitude of motion error of less than 0.2?mm for five, seven and ten bins. 4D-MRI provided excellent image quality for liver, kidney and pancreas. In patients, the median amplitude of motion seen on 4D-CT and 4D-MRI was 11.2?mm (range 2.8-20.3?mm) and 10.1?mm (range 0.7-20.7?mm) respectively. The median difference in amplitude between 4D-CT and 4D-MRI was -0.6?mm (range -3.4-5.2?mm). 4D-MRI demonstrated superior edge detection (median score 3 versus 1) and overall image quality (median score 2 versus 1) compared to 4D-CT.

Conclusions

The prototype 4D-MRI sequence demonstrated promising results and may be used in abdominal targeting, motion gating, and towards implementing MRI-based adaptive RT.

SUBMITTER: Oar A

PROVIDER: S-EPMC7807635 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Publications

Comparison of four dimensional computed tomography and magnetic resonance imaging in abdominal radiotherapy planning.

Oar Andrew A Liney Gary G Rai Robba R Deshpande Shrikant S Pan Li L Johnston Meredith M Jameson Michael M Kumar Shivani S Lee Mark M

Physics and imaging in radiation oncology 20180701

<h4>Background and purpose</h4>Four-dimensional (4D) computed tomography (CT) is widely used in radiotherapy (RT) planning and remains the current standard for motion evaluation. We assess a 4D magnetic resonance imaging (MRI) sequence in terms of motion and image quality in a phantom, healthy volunteers and patients undergoing RT.<h4>Materials and methods</h4>The 4D-MRI sequence is a prototype T1-weighted 3D gradient echo with radial acquisition with self-gating. The accuracy of the 4D-MRI resp ...[more]

PMID: 33458408

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Project description:PurposeTo investigate interobserver delineation variability for gross tumor volumes of primary lung tumors and associated pathologic lymph nodes using magnetic resonance imaging (MRI), and to compare the results with computed tomography (CT) alone- and positron emission tomography (PET)-CT-based delineations.Methods and materialsSeven physicians delineated the tumor volumes of 10 patients for the following scenarios: (1) CT only, (2) PET-CT fusion images registered to CT ("clinical standard"), and (3) postcontrast T1-weighted MRI registered with diffusion-weighted MRI. To compute interobserver variability, the median surface was generated from all observers' contours and used as the reference surface. A physician labeled the interface types (tumor to lung, atelectasis (collapsed lung), hilum, mediastinum, or chest wall) on the median surface. Contoured volumes and bidirectional local distances between individual observers' contours and the reference contour were analyzed.ResultsComputed tomography- and MRI-based tumor volumes normalized relative to PET-CT-based volumes were 1.62 ± 0.76 (mean ± standard deviation) and 1.38 ± 0.44, respectively. Volume differences between the imaging modalities were not significant. Between observers, the mean normalized volumes per patient averaged over all patients varied significantly by a factor of 1.6 (MRI) and 2.0 (CT and PET-CT) (P=4.10 × 10-5 to 3.82 × 10-9). The tumor-atelectasis interface had a significantly higher variability than other interfaces for all modalities combined (P=.0006). The interfaces with the smallest uncertainties were tumor-lung (on CT) and tumor-mediastinum (on PET-CT and MRI).ConclusionsAlthough MRI-based contouring showed overall larger variability than PET-CT, contouring variability depended on the interface type and was not significantly different between modalities, despite the limited observer experience with MRI. Multimodality imaging and combining different imaging characteristics might be the best approach to define the tumor volume most accurately.

Dataset Information

Comparison of four dimensional computed tomography and magnetic resonance imaging in abdominal radiotherapy planning.

Background and purpose

Materials and methods

Results

Conclusions

Publications

Comparison of four dimensional computed tomography and magnetic resonance imaging in abdominal radiotherapy planning.

Similar Datasets

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