Esophageal CancerNCT07416825
Inter-Observer Delineation Differences in Esophageal Cancer GTV on MR, CT, and PET/CT Protokol šečerov Ermenc 28dec19
A study testing Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emission Tomography/Computed Tomography (PET/CT) in people with Esophageal Cancer and Esophageal Carcinoma, run by Institute of Oncology Ljubljana at 1 site in Slovenia.
Trial summary
Esophageal cancer radiotherapy requires accurate delineation of the gross tumor volume (GTV) to ensure adequate tumor coverage and to minimize radiation dose to surrounding organs at risk. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Esophageal Cancer, Esophageal Carcinoma
- What is being tested?
- Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emission Tomography/Computed Tomography (PET/CT)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 23 participants
- Where
- 1 siteSlovenia
- Study dates
- 1 Jan 2020to 30 Jun 2021
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age ≥18 years
- Locally advanced esophageal cancer (T1b-4b, N0-N+, M0)
- Siewert type I or II for distal esophageal tumors
- Planned preoperative or definitive chemoradiotherapy
- Written informed consent for participation in the study
- No contraindications for MRI
Who cannot join
- Implanted metallic objects with magnetic properties or electromagnetic devices without MRI compatibility confirmation
- Physical or psychological conditions preventing informed consent
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Inter-observer Delination Variation in Esophageal Cancer Radiotherapy by Use of Magnetic Resonance
Esophageal cancer radiotherapy requires accurate delineation of the gross tumor volume (GTV) to ensure adequate tumor coverage and to minimize radiation dose to surrounding organs at risk. Computed tomography (CT) is routinely used for target delineation, while positron emission tomography-computed tomography (PET/CT) may provide additional functional information. However, uncertainty in tumor boundaries and inter-observer variation remain clinically relevant issues.
Magnetic resonance imaging (MRI) provides improved soft tissue contrast and diffusion-weighted imaging (DWI) information, which may improve visualization of esophageal tumors. This study evaluates whether MRI-based imaging, alone or fused with CT or PET/CT, reduces inter-observer variation in GTV delineation compared with standard CT and PET/CT-based delineation.
A total of 21 patients with locally advanced esophageal cancer undergoing standard radiotherapy preparation will undergo MRI simulation in addition to routine CT and PET/CT simulation. Five experienced radiation oncologists will independently delineate the primary tumor GTV on CT, MRI, PET/CT, CT-MRI fusion, and PET/CT-MRI fusion datasets. Inter-observer variation will be assessed using conformity indices and spatial analysis tools.
Read the detailed description
Accurate target volume delineation is essential in radiotherapy for esophageal cancer, as contouring uncertainty may lead to geographic miss or increased dose to organs at risk. CT imaging is the standard modality used for radiotherapy planning; however, CT has limited soft tissue contrast, which can make delineation of the proximal and distal tumor extent challenging. PET/CT may assist in staging and may provide functional tumor information, but its value for precise target delineation remains uncertain.
MRI has recently gained importance in radiotherapy planning due to improved anatomical soft tissue visualization and functional imaging such as diffusion-weighted imaging (DWI). Technical advances have improved thoracic MRI feasibility, and MRI may allow improved identification of tumor borders in the esophagus. The clinical role of MRI in reducing inter-observer delineation variability in esophageal cancer radiotherapy planning is not yet well established.
This prospective study compares inter-observer variation in gross tumor volume (GTV) delineation across different imaging modalities used in radiotherapy preparation. Patients with locally advanced esophageal cancer will undergo standard PET/CT simulation according to institutional protocol and additional MRI simulation performed with identical immobilization. MRI will include T2-weighted sequences and DWI sequences without intravenous contrast.
Five experienced radiation oncologists will independently delineate the primary tumor GTV on anonymized datasets using the Eclipse treatment planning system. Contouring will be performed separately on the following image sets: CT, MRI, PET/CT, CT fused with MRI, and PET/CT fused with MRI. Pathologic lymph nodes will not be included in the GTV. A washout period of at least 14 days will be maintained between contouring sessions for the same patient on different imaging modalities.
Inter-observer variation will be assessed using the generalized conformity index (CIgen). Additionally, reference contours will be generated using the STAPLE algorithm. The Contour Analysis Tool (CAT) will be used to calculate planar and volumetric conformity indices (PCI and VCI) and to perform spatial analysis based on inter-delineation distance measurements. Contouring time, image quality, and perceived delineation difficulty will also be recorded by observers.
The primary objective is to determine whether MRI-based imaging reduces inter-observer variability in GTV delineation compared with standard CT and PET/CT imaging in esophageal cancer radiotherapy planning.
- Conditions
- Esophageal Cancer, Esophageal Carcinoma
- Being tested
- Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography/Computed Tomography (PET/CT), CT-MRI Image Fusion, PET/CT-MRI Image Fusion
- Keywords
- Radiotherapy Planning, Target Volume Delineation
- Medical subject headings
- Esophageal Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Computed Tomography (CT)Diagnostic test
CT imaging performed as part of standard radiotherapy simulation and planning for esophageal cancer. CT datasets are used for gross tumor volume (GTV) delineation.
Magnetic Resonance Imaging (MRI)Diagnostic test
MRI performed on a radiotherapy MRI simulator (T2-weighted sequences and diffusion-weighted imaging) using the same immobilization as CT/PET-CT simulation. MRI datasets are used for GTV delineation.
Positron Emission Tomography/Computed Tomography (PET/CT)Diagnostic test
FDG PET/CT imaging performed as part of standard radiotherapy preparation. PET/CT datasets are used for GTV delineation, with contouring performed on CT and adjusted using PET information when appropriate.
CT-MRI Image FusionDiagnostic test
Image registration and fusion of MRI with CT datasets for radiotherapy planning. Fused CT-MRI images are used for GTV delineation to evaluate the effect of MRI information on contouring variability.
PET/CT-MRI Image FusionDiagnostic test
Image registration and fusion of MRI with PET/CT datasets for radiotherapy planning. Fused PET/CT-MRI images are used for GTV delineation to evaluate inter-observer variation compared with standard PET/CT-based contouring.
| Study group | Role | What they receive |
|---|---|---|
| CT | Active comparator | Standard planning CT for GTV delineation. Receives: Diagnostic Test: Computed Tomography (CT) |
| MRI | Experimental | MRI simulation for GTV delineation. Receives: Diagnostic Test: Magnetic Resonance Imaging (MRI) |
| PET/CT | Active comparator | PET/CT simulation for GTV delineation. Receives: Diagnostic Test: Positron Emission Tomography/Computed Tomography (PET/CT) |
| CT + MRI Fusion | Experimental | CT images fused with MRI for GTV delineation. Receives: Diagnostic Test: CT-MRI Image Fusion |
| PET/CT + MRI Fusion | Experimental | PET/CT images fused with MRI for GTV delineation. Receives: Diagnostic Test: PET/CT-MRI Image Fusion |
What is being measured
The primary outcome is the main question the study is designed to answer.
Volumetric Conformity Index (VCI) Compared With Reference Contour
Volumetric conformity index (VCI) will be calculated using the Contour Analysis Tool (CAT) by comparing each observer's gross tumor volume (GTV) contour to a reference contour generated using the STAPLE algorithm. VCI is defined as the ratio of intersection volume to union volume and ranges from 0 to 1. The outcome will be reported as mean VCI for each imaging dataset.
Measured: Up to 14 days after completion of contouring for each imaging dataset
Inter-observer Variability in GTV Delineation (Generalized Conformity Index, CIgen)
Inter-observer agreement in gross tumor volume (GTV) delineation will be assessed using the generalized conformity index (CIgen) calculated using the Contour Analysis Tool (CAT). CIgen is defined as the ratio of the sum of pairwise intersections to the sum of pairwise unions of all observers' contours and ranges from 0 to 1. The outcome will be reported as CIgen for each imaging dataset.
Measured: Up to 14 days after completion of contouring for each imaging dataset
Image Quality Rating (5-point Likert Scale)
Observers will rate the image quality of each imaging dataset (CT, MRI, PET/CT, CT-MRI fusion, PET/CT-MRI fusion) using a 5-point Likert scale (1 = very poor, 5 = excellent). The outcome will be reported as mean image quality score.
Measured: During contouring sessions (up to 14 days per imaging dataset)
Secondary outcomes (4)
Planar Conformity Index (PCI) Compared With Reference Contour
Planar conformity index (PCI) will be calculated using the Contour Analysis Tool (CAT) by comparing each observer's GTV contour to a reference contour generated using the STAPLE algorithm. PCI is defined as the ratio of intersection area to union area and ranges from 0 to 1. The outcome will be reported as mean PCI for each imaging dataset.
Measured: Up to 14 days after completion of contouring for each imaging dataset
Spatial Inter-delineation Distance (IDD) Between Observer Contours and Reference Contour
Inter-delineation distance (IDD) will be calculated using the Contour Analysis Tool (CAT) as the shortest distance between each observer's GTV contour and the reference contour, expressed in millimeters (mm). The outcome will be reported as mean IDD (mm) for each imaging dataset.
Measured: Up to 14 days after completion of contouring for each imaging dataset
Contouring Time
Time required for gross tumor volume (GTV) delineation will be recorded for each observer and imaging dataset and reported in minutes.
Measured: During contouring sessions (up to 14 days per imaging dataset)
Perceived Difficulty of Delineation (5-point Likert Scale)
Observers will rate the perceived difficulty of GTV delineation for each imaging dataset using a 5-point Likert scale (1 = very easy, 5 = very difficult). The outcome will be reported as mean difficulty score.
Measured: During contouring sessions (up to 14 days per imaging dataset)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Feb 2026
- Study start1 Jan 2020
- Primary completion30 Jun 2021
- Study completion30 Jun 2021
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Esophageal CancerStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Factorial
- Model description
- Participants undergo multiple imaging modalities (CT, PET/CT, MRI) for radiotherapy planning. Target volume delineations are compared across modalities within the same participants.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 23 participants (actual)
Sponsor and investigators
- Lead sponsor
- Institute of Oncology Ljubljana
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07416825
- Sponsor's protocol ID
- ERID-KSOPKR-0005/2020
- Other IDs
- ARRS / ID: 33071
- Status last verified
- Feb 2026
- First submitted
- 6 Feb 2026
- Last updated
- 18 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Inter-observer Delination Variation in Esophageal Cancer Radiotherapy by Use of Magnetic Resonance
- ClinicalTrials.gov ID
- NCT07416825
- Acronym / sponsor ID
- ERID-KSOPKR-0005/2020
- Conditions
- Esophageal Cancer, Esophageal Carcinoma
- Keywords
- Radiotherapy Planning, Target Volume Delineation
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 23 participants (actual)
- Lead sponsor
- Institute of Oncology LjubljanaUniversity, hospital or other
- Study start
- 1 Jan 2020 (actual)
- Primary completion
- 30 Jun 2021 (actual)
- Study completion
- 30 Jun 2021 (actual)
- First posted
- 18 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Esophageal cancer radiotherapy requires accurate delineation of the gross tumor volume (GTV) to ensure adequate tumor coverage and to minimize radiation dose to surrounding organs at risk. Computed tomography (CT) is routinely used for target delineation, while positron emission tomography-computed tomography (PET/CT) may provide additional functional information. However, uncertainty in tumor boundaries and inter-observer variation remain clinically relevant issues.
Magnetic resonance imaging (MRI) provides improved soft tissue contrast and diffusion-weighted imaging (DWI) information, which may improve visualization of esophageal tumors. This study evaluates whether MRI-based imaging, alone or fused with CT or PET/CT, reduces inter-observer variation in GTV delineation compared with standard CT and PET/CT-based delineation.
A total of 21 patients with locally advanced esophageal cancer undergoing standard radiotherapy preparation will undergo MRI simulation in addition to routine CT and PET/CT simulation. Five experienced radiation oncologists will independently delineate the primary tumor GTV on CT, MRI, PET/CT, CT-MRI fusion, and PET/CT-MRI fusion datasets. Inter-observer variation will be assessed using conformity indices and spatial analysis tools.
Detailed description
Accurate target volume delineation is essential in radiotherapy for esophageal cancer, as contouring uncertainty may lead to geographic miss or increased dose to organs at risk. CT imaging is the standard modality used for radiotherapy planning; however, CT has limited soft tissue contrast, which can make delineation of the proximal and distal tumor extent challenging. PET/CT may assist in staging and may provide functional tumor information, but its value for precise target delineation remains uncertain.
MRI has recently gained importance in radiotherapy planning due to improved anatomical soft tissue visualization and functional imaging such as diffusion-weighted imaging (DWI). Technical advances have improved thoracic MRI feasibility, and MRI may allow improved identification of tumor borders in the esophagus. The clinical role of MRI in reducing inter-observer delineation variability in esophageal cancer radiotherapy planning is not yet well established.
This prospective study compares inter-observer variation in gross tumor volume (GTV) delineation across different imaging modalities used in radiotherapy preparation. Patients with locally advanced esophageal cancer will undergo standard PET/CT simulation according to institutional protocol and additional MRI simulation performed with identical immobilization. MRI will include T2-weighted sequences and DWI sequences without intravenous contrast.
Five experienced radiation oncologists will independently delineate the primary tumor GTV on anonymized datasets using the Eclipse treatment planning system. Contouring will be performed separately on the following image sets: CT, MRI, PET/CT, CT fused with MRI, and PET/CT fused with MRI. Pathologic lymph nodes will not be included in the GTV. A washout period of at least 14 days will be maintained between contouring sessions for the same patient on different imaging modalities.
Inter-observer variation will be assessed using the generalized conformity index (CIgen). Additionally, reference contours will be generated using the STAPLE algorithm. The Contour Analysis Tool (CAT) will be used to calculate planar and volumetric conformity indices (PCI and VCI) and to perform spatial analysis based on inter-delineation distance measurements. Contouring time, image quality, and perceived delineation difficulty will also be recorded by observers.
The primary objective is to determine whether MRI-based imaging reduces inter-observer variability in GTV delineation compared with standard CT and PET/CT imaging in esophageal cancer radiotherapy planning.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Factorial
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 5
- Model description
- Participants undergo multiple imaging modalities (CT, PET/CT, MRI) for radiotherapy planning. Target volume delineations are compared across modalities within the same participants.
| Arm | Type | Receives |
|---|---|---|
| CT | Active comparator | Diagnostic Test: Computed Tomography (CT)Standard planning CT for GTV delineation. |
| MRI | Experimental | Diagnostic Test: Magnetic Resonance Imaging (MRI)MRI simulation for GTV delineation. |
| PET/CT | Active comparator | Diagnostic Test: Positron Emission Tomography/Computed Tomography (PET/CT)PET/CT simulation for GTV delineation. |
| CT + MRI Fusion | Experimental | Diagnostic Test: CT-MRI Image FusionCT images fused with MRI for GTV delineation. |
| PET/CT + MRI Fusion | Experimental | Diagnostic Test: PET/CT-MRI Image FusionPET/CT images fused with MRI for GTV delineation. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Age ≥18 years
- Locally advanced esophageal cancer (T1b-4b, N0-N+, M0)
- Siewert type I or II for distal esophageal tumors
- Planned preoperative or definitive chemoradiotherapy
- Written informed consent for participation in the study
Key exclusion criteria (2 listed)
- Implanted metallic objects with magnetic properties or electromagnetic devices without MRI compatibility confirmation
- Physical or psychological conditions preventing informed consent
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Computed Tomography (CT)CT imaging performed as part of standard radiotherapy simulation and planning for esophageal cancer. CT datasets are used for gross tumor volume (GTV) delineation. | Diagnostic test | CT |
| Magnetic Resonance Imaging (MRI)MRI performed on a radiotherapy MRI simulator (T2-weighted sequences and diffusion-weighted imaging) using the same immobilization as CT/PET-CT simulation. MRI datasets are used for GTV delineation. | Diagnostic test | MRI |
| Positron Emission Tomography/Computed Tomography (PET/CT)FDG PET/CT imaging performed as part of standard radiotherapy preparation. PET/CT datasets are used for GTV delineation, with contouring performed on CT and adjusted using PET information when appropriate. | Diagnostic test | PET/CT |
| CT-MRI Image FusionImage registration and fusion of MRI with CT datasets for radiotherapy planning. Fused CT-MRI images are used for GTV delineation to evaluate the effect of MRI information on contouring variability. | Diagnostic test | CT + MRI Fusion |
| PET/CT-MRI Image FusionImage registration and fusion of MRI with PET/CT datasets for radiotherapy planning. Fused PET/CT-MRI images are used for GTV delineation to evaluate inter-observer variation compared with standard PET/CT-based contouring. | Diagnostic test | PET/CT + MRI Fusion |
Primary outcome
Volumetric Conformity Index (VCI) Compared With Reference Contour
Time frame: Up to 14 days after completion of contouring for each imaging dataset
Volumetric conformity index (VCI) will be calculated using the Contour Analysis Tool (CAT) by comparing each observer's gross tumor volume (GTV) contour to a reference contour generated using the STAPLE algorithm. VCI is defined as the ratio of intersection volume to union volume and ranges from 0 to 1. The outcome will be reported as mean VCI for each imaging dataset.
Inter-observer Variability in GTV Delineation (Generalized Conformity Index, CIgen)
Time frame: Up to 14 days after completion of contouring for each imaging dataset
Inter-observer agreement in gross tumor volume (GTV) delineation will be assessed using the generalized conformity index (CIgen) calculated using the Contour Analysis Tool (CAT). CIgen is defined as the ratio of the sum of pairwise intersections to the sum of pairwise unions of all observers' contours and ranges from 0 to 1. The outcome will be reported as CIgen for each imaging dataset.
Image Quality Rating (5-point Likert Scale)
Time frame: During contouring sessions (up to 14 days per imaging dataset)
Observers will rate the image quality of each imaging dataset (CT, MRI, PET/CT, CT-MRI fusion, PET/CT-MRI fusion) using a 5-point Likert scale (1 = very poor, 5 = excellent). The outcome will be reported as mean image quality score.
4 secondary outcomes
Planar Conformity Index (PCI) Compared With Reference Contour
Time frame: Up to 14 days after completion of contouring for each imaging dataset
Spatial Inter-delineation Distance (IDD) Between Observer Contours and Reference Contour
Time frame: Up to 14 days after completion of contouring for each imaging dataset
Contouring Time
Time frame: During contouring sessions (up to 14 days per imaging dataset)
Perceived Difficulty of Delineation (5-point Likert Scale)
Time frame: During contouring sessions (up to 14 days per imaging dataset)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Feb 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emission Tomography/Computed Tomography (PET/CT) in people with Esophageal Cancer and Esophageal Carcinoma, run by Institute of Oncology Ljubljana at 1 site in Slovenia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 18 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Slovenia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Volumetric Conformity Index (VCI) Compared With Reference Contour (time frame: Up to 14 days after completion of contouring for each imaging dataset). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Feb 2026.