PET/MR for Rectal Cancer Treatment Monitoring and Surveillance

Study Overview
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Brief Summary
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The goal of pilot study is to assess the feasibility of FDG-PET/MRI for monitoring rectal cancer disease status in the setting of rectal cancer non-operative management (NOM). Data from this study will be used to guide the design of future clinical trials involving FDG-PET/MRI for rectal cancer NOM.

Official Title
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A Pilot Study of PET/MR for Rectal Cancer Treatment Monitoring and Surveillance

Conditions
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Rectal Cancer, Cancer of the Rectum

Intervention / Treatment
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* Device: FDG PET/MRI


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: At least 18 years of age Biopsy-proven rectal adenocarcinoma of the rectum with clinically suspected or previously known stage I-IIIB (cT1-4, N0-2, M0) disease Anticipated or prior chemoradiation as part of an NOM treatment strategy Ability to understand and willingness to sign an IRB-approved written informed consent document Exclusion Criteria: Prior surgical resection of rectal cancer (endoscopic or TME) Contraindication to MRI Comorbidities that would limit patient's ability to cooperate with a PET/MRI examination (e.g. dementia, inability to follow commands, claustrophobia, tremors, requirement for oxygen by nasal cannula, etc…). Implanted devices or materials that may interfere with MRI imaging or create significant artifact Pregnancy Contraindication to gadolinium contrast or FDG End-stage renal disease

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: FDG PET/MRI<br>-Patients will undergo FDG-PET/MRI in lieu of the standard pelvic MRI at up to 6 time-points at which it would normally be performed in their care for the period of time extending 30-36 months from the time of enrollment (depending on enrollment point). In the surveillance period, when patients typically undergo pelvic MRI every 3 months, the FDG-PET/MRI will be done in lieu of the standard pelvic MRI on an approximately every-other-scan basis. In other words, the FDG-PET/MRI will occur roughly once every 6 months. | Device: FDG PET/MRI<br>* -All patients will undergo a simultaneous list mode PET and MR acquisition beginning 55-65 minutes after administration of FDG according to a standard weight-based scale.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Technical Feasibility of PET/MRI as Measured by the Completion of the Study With Acceptable Image Quality in ≥70% of Scans | -For patients imaged at multiple time points after enrollment, all available PET/MRIs will be included in the feasibility analysis. Patients able to remain on the scanner for the full duration of the planned data acquisition without any serious adverse events will be considered to have completed the PET/MRI rectal cancer protocol. Image quality will be assessed by the Principal Investigator on review at a dedicated workstation with specialized PET/MR software. A standardized Likert-based scoring scheme will be utilized to capture subjective assessments of image contrast (1 = worst; 5 = best), image resolution (1 = worst; 5 = best), and image artifact 'freeness' (1 = worst; 5 = best). Image sets scoring ≥ 3 in all three categories will be considered of acceptable quality. | Up to 12 months after completion of enrollment of all patients (26 months) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Scans With Changes in Perceived Disease Status as Measured by PET/MRI Tumor Regression Grade Relative to the Conventional MRI Only Tumor Regression Grade | The study reader will interpret the MRI for the tumor regression grade and then will interpret the PET/MRI for the tumor regression grade. The tumor regression grade is a five-tier imaging-based scoring system based on the ability to distinguish between tumor and fibrosis. mrTRG 1, low signal fibrosis only, no tumor signal; mrTRG 2, more than 75 per cent fibrosis and minimal tumor signal intensity; mrTRG 3, 50 per cent tumor/fibrosis; mrTRG 4, less than 25 per cent fibrosis, predominant tumor signal; and mrTRG 5, no fibrosis | Up to 12 months after completion of enrollment of all patients (26 months) |