Standardized Uptake Values (SUVs), normalized activity concentration, measured using PET/MR have inaccuracies ≥ 20% which exceeds National Cancer Institute / American College of Radiology Imaging Network (NCI/ACRIN), Radiological Society of North America / Quantitative Imaging Biomarkers Alliance (RSNA/QIBA) specifications and disqualifies PET/MR from multicenter or cooperative group clinical trials. High inaccuracy is primarily due to poor attenuation correction (AC) owing to lack of computed tomography (CT) data. This study will develop acquisition and analyses methods to synthesize CT images from MR data that can be used to achieve SUVs that are within 5% of those obtained using PET/CT (reference standard), thus meeting accuracy requirements needed to qualify for multicenter trials.

The overall goal of this research project is to validate clinically practical methods for producing MR-based attenuation correction information which is needed to produce quantitatively accurate PET images from a PET/MR scanner. Existing commercial PET/MR systems use methods that are inaccurate.

Objective The primary objective is to demonstrate that, using the new acquisition and analysis methods for MR-AC, PET SUVs in lesions and normal tissues can be measured using PET/MR and be within 5% agreement of those measured using PET/CT.

The secondary objective is to demonstrate visual and quantitative agreement between synthesized CT images generated from MR data and the reference, measured CT images.

Study Design This study would like to enroll patients receiving a clinically indicated PET/CT scan. The patients will be asked to agree to a receive research PET/MR scan within the study which requires additional time and potential MR risks for the patient. It does not entail extra injections or radiation exposure. Research acquisition and processing will be performed on the PET/MR data to create PET images that are expected to have quantitatively accurate SUVs. These will be compared to SUVs from the clinical PET/CT which will serve as the reference standard.

Outcome By bringing together cutting-edge advances in both MR acquisition and image analyses, the successful completion of these aims will achieve SUVs that are within 5% of those obtained with PET/CT (reference standard) with clinically appropriate acquisition time, image quality, and diagnostic accuracy, so that PET/MR systems meet SUV accuracy requirements needed to qualify for cooperative group clinical trials.

Inclusion Criteria:

• Receiving PET/CT at University Hospitals Cleveland Medical Center (UHCMC) for a clinical indication
• No Contraindications to undergo MR as assessed using University Hospitals (UH) Radiology standard MR assessment form
• Has the ability to understand and willingness to sign a written informed consent
• The circumference of the volunteer in the body section, as determined using a measuring tape, to be scanned must be less than or equal to 110 cm to avoid field of view limitations on the PET/MR

Exclusion Criteria:

• Patient size or circumference greater than the MR gantry of the PET/MR.
• Pregnancy or lactation.
• Contraindications to undergo MR as assessed using UH Radiology standard MR assessment form.
• Claustrophobia or inability to tolerate MR examination (lay still for approximately 1 hour and hold breath intermittently).
• Individuals who are not willing or capable of giving informed consent or assent (with legal guardian consent).

Patients receiving PET/CT at University Hospitals Cleveland Medical Center (UHCMC) for a clinical indication