PET displays the functional status of the body’s tissues at the cellular level,detecting metabolic abnormalities in a tumor even before disease has manifested itself in structural changes. In cases where an abnormality has already been identified in anatomic studies, fluorine-18 fluorodeoxyglucose (FDG) PET can help differentiate benign from malignant findings. PET imaging helps find metastatic disease that can be difficult to detect by anatomic imaging alone. Correlation with CT adds specificity by localizing the findings anatomically.

PET has proven extremely valuable in the diagnosis of pulmonary nodules, in the staging and restaging of patients with known malignancies, and in monitoring intermediate response to therapy. It can also be used to evaluate equivocal CT or MRI findings and to assist in radiation therapy planning.

We offer two kinds of examination:

• PET/CT
  This is a diagnostic PET imaging study, accompanied by a low-dose CT scan without contrast, performed for attenuation correction and for fusion with the PET images for anatomic correlation. No diagnostic CT scan is performed.
• PET with Diagnostic CT - This diagnostic PET imaging study, is immediately followed by a diagnostic CT scan with IV and/or enteric contrast. This option allows the oncology patient to complete both exams at one time. The PET/CT study is interpreted jointly by experienced specialists in PET and CT imaging, yielding a report that combines the findings of both scans.

PET/CT technology has demonstrated high sensitivity and specificity for a wide range of malignancies, including:

• Lymphoma
• Melanoma
• Head and neck carcinomas
• Thyroid carcinoma
• Solitary pulmonary nodule
• Non-small-cell lung carcinoma
• Breast carcinoma
• Esophageal carcinoma
• Colorectal carcinoma
• Ovarian carcinoma
• Cervical carcinoma
• Uterine carcinoma
• Testicular carcinoma

Preparation
The PET imaging session entails an intravenous injection of F-18 fluorodeoxyglucose (FDG), an analog of glucose labeled with a short-lived radioactive isotope of fluorine. Patients are instructed to fast for four to six hours prior to the test to ensure proper FDG uptake. Physicians are requested to advise diabetic patients on glucose management the day of the test, taking into account the patient’s fasting. Insulin should not be administered for 2 hours prior to the test. Patients should advise us of any special conditions (e.g., allergy to intravenous contrast dye, diabetes, or kidney disease) and should alert us to any need for sedation due to claustrophobia. Patients who are pregnant or breast-feeding should contact us before scheduling an appointment.

Once injected, the patient relaxes in a quiet room for approximately 60 minutes before the PET scan, which lasts approximately 30 minutes. Patients who are candidates for a diagnostic CT are prepped before the PET scan with oral and, when indicated, rectal contrast, and administered an IV contrast infusion for the contrast-enhanced CT scan, which is performed a few minutes after the PET scan.

PET examination of the brain is used for the differential diagnosis of Alzheimer’s disease in patients who have experienced memory or cognitive decline of six months’ duration or longer, and whose CT or MRI scans are negative or inconclusive.

Preparation
The PET session entails an FDG injection, and patients are requested to fast for four to six hours prior to the test to ensure proper FDG uptake. Physicians will advise diabetic patients on glucose management the day of the test, taking into account the patient’s fasting. Insulin should not be administered for 2 hours prior to the test. Patients should advise us of any special conditions (e.g., allergy to intravenous contrast dye, diabetes, or kidney disease) and should alert us to any need for sedation due to claustrophobia. Patients who are pregnant or breast-feeding should contact us before scheduling an appointment.

The test entails 60 minutes rest following the FDG injection and 30 minutes for the PET scan, with the possibility of performing an IV contrast-enhanced CT scan a few minutes thereafter.

PET imaging of the heart offers a high-quality, comprehensive noninvasive cardiac assessment. We perform pharmacologic-stress and at-rest myocardial perfusion imaging, cardiac wall motion evaluation, ventricular function quantification, and coronary flow reserve quantification. In patients with poor left ventricular function, we perform metabolic myocardial viability imaging, which is used to differentiate myocardial hibernation from scarring.

Mount Sinai offers two cardiologic examinations:

• Myocardial perfusion/function imaging - The PET/CT scan encompasses rest and pharmacological stress rubidium-82 PET perfusion imaging, the most accurate physiologic method of detection of coronary disease, along with global and regional ventricular function assessment, all in 35 minutes. The service also provides quantification of coronary flow reserve, a tool unique to PET imaging, to help detect early disease and characterize the true extent of multivessel disease. In selected patients, an icepressor stress test can be performed to detect coronary spasm and/or endothelial dysfunction. PET myocardial perfusion imaging is particularly helpful in women, in obese patients, and in patients with previous non-diagnostic or contradictory tests.
• Myocardial Viability - Imaging of myocardial viability is indicated in patients with poor left ventricular function due to coronary artery disease. Myocardial metabolic imaging with FDG, in combination with myocardial perfusion imaging, increases the accuracy of predicting improvement or lack of improvement of ventricular function after revascularization. Myocardial metabolic PET imaging helps the clinician select revascularization versus medical therapy for heart transplantation in high-risk patients.

Preparation
Patients are asked to abstain for 24 hours from caffeine or caffeine-containing products, such as coffee, tea, or chocolate, and even from decaffeinated drinks (which do contain small amounts of caffeine that interfere with pharmacologic stress agents). Patients should fast for 4-6 hours before the scheduled appointment time.

Patients should advise us of any special conditions, such as allergy to intravenous contrast dye, diabetes, or kidney disease, and should alert us of any need for sedation due to claustrophobia. Patients who are pregnant or breast-feeding should contact us before scheduling an appointment.

The PET myocardial perfusion/function examination requires approximately 15-20 minutes of preparation and 35 minutes for imaging.

For myocardial viability PET studies, which can be performed either on the same or a different day, an additional two-and-a-half hours are required: about one hour for monitoring and adjustment of blood glucose with IV glucose and insulin, followed by an injection of FDG. This is followed by resting quietly for one hour, followed by 20 minutes of imaging.