PET/CT-Assessment of Liver Tumor Ablation

In this research study, the investigators are evaluating whether ammonia PET scans or FDG PET perfusion scans are more useful in helping radiologists determine whether liver tumors were successfully destroyed by the heating or freezing procedures (ablations) than other scans currently available to radiologists, such as CT scans and MRI scans.

The currently available scan (usually a CT scan with contrast dye) is not always effective in showing how completely the tumor has been destroyed. The ammonia PET scan is a different way of looking at how much tumor has been destroyed. This study will compare the standard scan (CT scan) with the ammonia PET scan.

The plan for this study involves the non-therapeutic administration of a radiopharmaceutical, N-13 ammonia or F-18 fluorodeoxyglucose, one to two doses, during the tumor ablation procedure. The perfusion PET scan is a diagnostic imaging test. The tumor ablation procedure is performed according to our standard clinical practice and is not itself a research activity. The use of N-13 ammonia or F-18 fluorodeoxyglucose to image liver perfusion with a PET scanner is the research portion of the procedure. The patient will receive one or two doses of N-13 ammonia (10 mCi (millicurie)/dose) for intraprocedural assessment of ablation results. Not more than two doses will be administered and one or both doses will be administered on the day of the tumor ablation procedure only. The ammonia perfusion scan will not be used to change or modify the ablation procedure.

After the screening procedures confirm that that the participant is eligible to participate in the research study:

* Ammonia Perfusion PET: The participant will be scheduled for the tumor ablation procedure as part of the participant's routine care. If the participant decided to take part in this research study, then the participant will have one or two ammonia perfusion PET scans during the ablation procedure to see if the ablation was successful or not as compared to standard CT scanning. The ammonia perfusion PET scans are the research part of the participant's procedure. The rest of the participant's procedure is not research. The participant will receive one or two doses of the radioactive tracer called N-13 ammonia. This tracer is administered through the same IV (thin tube placed in a vein) used by the Anesthesiologist to give the participant routine medications that relax the participant, prevent pain, and allow the participant to sleep during the procedure. This tracer does not treat the participant's tumor in any way. Instead, the tracer may allow the radiologist to better see how much of the participant's tumor was destroyed.
* Photographs: Photographs may be taken during the procedure. Care will be taken to ensure these do not reveal the participant's identity.
* Clinic visits: The investigators routinely see patients after tumor ablation procedures within one to two weeks after the procedure and then every three months after the procedure for one to two years, and as needed in the future. Accordingly, the clinic visits are routine and not an added research commitment.

Eligibility Criteria:
Inclusion Criteria:

* Adults, 18 years or older
* Referral from an internist, oncologist, or surgeon for liver tumor ablation consultation
* ECOG (Eastern Cooperative Oncology Group) Performance Status \< 3
* Liver tumor ablation judged to be appropriate based on clinical assessment in the BWH (Brigham \& Women's Hospital) Tumor Ablation Clinic by the tumor ablation interventional radiologist, per standard clinical practice
* Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

* Uncorrectable coagulopathy (due to bleeding risk)
* Pulmonary disease precluding monitored anesthesia care or general anesthesia
* Severe renal insufficiency, EGFR (estimated glomerular filtration rate) \< 30
* Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, significant cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
* Childs-Pugh Class C cirrhosis
* Occlusive main portal vein thrombosis
* Presence of biliary-enteric anastomosis (due to risk of biliary infection)
* Pregnant women are excluded (because both CT and PET/CT scans involve the use of ionizing radiation which may pose a potential teratogenic effect on the fetus.)