Cardiac F-18 FDG PET Table 3. Cardiac F-18 FDG PET Table 4. Elements of a comprehensive FDG report Parameter Recommendation Sections Information included Tracer dose (mCi) 5-10 (3D mode); Demographics • Patient demographics 10-15 (2D mode) • Study indications • Coronary anatomy if known Delay after injection (min) 45-60 (nondiabetics); and 2). Use of IV insulin (even in non-diabetic patients) is OVERVIEW 60-90 (diabetics) Methods • Technique and radiotracer dose for desirable whenever feasible in order to promote maximum perfusion and FDG imaging The purpose of this document is to specifically uptake of FDG by the normal myocardium and optimal Patient positioning Supine position • Stress test hemodynamic informa- identify the critical steps involved in perform- image quality. Following FDG injection, monitoring of the (arms up preferred) tion (when available) ing and interpreting a myocardial viability patient’s glucose levels should be continued until a stable Imaging mode 2D or 3D; list, gated or • Glucose loading technique study with F-18 labeled fluoro-deoxyglucose glucose level is ensured and the patient is asymptomatic. static (glucose load and insulin) (FDG) positron emission tomography (PET). Diabetic Patients: Diabetic patients have a limited ability This document will cover indications, patient Image duration (min) 10-30 (depends on count Findings: • Size, severity, and location of the to produce endogenous insulin and are less responsive to rate and dose) MPI and FDG stress (when available) and rest preparation, testing procedure, interpreta- insulin. For these reasons, standard glucose loading tech- perfusion defects tion, and reporting for FDG PET. niques may be less effective in such patients. The use of Attenuation correction Before or immediately • The magnitude of reversible/fixed higher doses of insulin accompanied by the close moni- after emission scan using perfusion defects toring of blood glucose (Table 2) can yield satisfactory radionuclide or CT • Magnitude of FDG uptake in seg- BACKGROUND results. Alternative protocols such as the euglycemic hyper- transmission imaging ments with rest perfusion defects The detection of dysfunctional, hibernating myocardium insulinemic clamp or the use of acipimox are listed in the Reconstruction method FBP or OSEM and abnormal wall motion. that can be improved by revascularization is important in ASNC Imaging Describe perfusion-metabolism the management of patients with ischemic heart disease. Guidelines for Reconstructed pixel size 2-5 mm pattern (match, mismatch, non- Hibernating myocardium results from the functional Nuclear Cardiology transmural match) adaptation of the myocardium to reduced resting myocar- Procedures. dial perfusion. PET with F-18 FDG is widely used in the FBP = Filtered back projection, OSEM = Ordered subset expectation Gated MPI • Left ventricular ejection fraction evaluation and management of patients with suspected TEST maximization (iterative reconstruction) • Regional wall motion ischemic left ventricular (LV) systolic dysfunction. PROCEDURE • Left ventricular volumes 1. Gated rest INDICATIONS magnitude of ischemia, scar, and hibernation, but also Conclusions • Overall interpretation of the find- myocardial FDG PET imaging is indicated for patients with LV factors such as low baseline LV ejection fraction, dilat- ings (scar, reversible perfusion perfusion dysfunction due to coronary artery disease who are eligible ed LV volume, delayed time to revascularization, and defects, hibernation, or combined single photon for coronary revascularization and have resting myocardial large scar which may adversely affect the recovery of findings) for each affected vascular emission perfusion defects in order to differentiate viable (i.e., function post revascularization. distribution. computed hibernation) from non-viable myocardium (i.e., scar). • A statement about estimated like- tomography SUGGESTED READING (SPECT) or lihood of recovery of function PATIENT PREPARATION Dilsizian V, Bacharach SL, Beanlands RS, et al. Imaging based on combining all available PET should always precede FDG cardiac PET imaging The test should be performed following a 6- to 12-hour guidelines for nuclear cardiology procedures: PET myocar- pertinent data from study. so that areas of hypoperfusion are identified. ECG- fast followed by a glucose load. Under glucose-loaded dial perfusion and metabolism clinical imaging. J Nucl gated myocardial perfusion imaging (MPI) can also conditions, FDG uptake by the normal myocardium is Cardiol 2009;16:doi: 10.1007/s12350-009-9094-9. provide additional useful information regarding the LV maximized, resulting in superior image quality and volumes. A severely dilated left ventricle is unlikely to reduced regional variation in FDG uptake. There are ASNC thanks the following members for their contribu- recover global function even if FDG uptake is present several approaches to stimulate myocardial glucose uptake tions to this document: Writing Group: Sharmila Dorbala, The 2011 Practice Points program is supported by Astellas in segments with contractile dysfunction. following oral or intravenous (IV) glucose loading. The MD (Chair); Ron Blankstein, MD; Fabio Esteves, MD; Pharma US, Inc., Bracco Diagnostics Inc., Covidien-Mallinckrodt, 2. Unless contraindications for stress testing exist, it is most common method is to use 25-100 g of oral glucose Maria Sciammarella, MD. Reviewers: Vasken Dilsizian, GE Healthcare, and Lantheus Medical Imaging. suggested that stress MPI be performed to identify the followed by supplemental IV insulin as needed (Tables 1 MD; Edward P. Ficaro, PhD; Christopher L. Hansen, MD. presence and amount of reversible perfusion defects. This is because patients with moderate-to-severe American Society of Nuclear Cardiology www.asnc.org/practicepoints 4340 East-West Highway, Suite 1120 Bethesda, MD 20814-4578 www.asnc.org Last updated: August 2011 4 Cardiac F-18 FDG PET functional recovery following revascularization. Table 1. Patient preparation guidelines: an overview of oral glucose loading protocol b. Absent myocardial perfusion with absent FDG uptake is called a match pattern and represents PROCEDURE STEPS TECHNIQUE transmural scar. This is the classic pattern associat- Fasting STEP 1: Fast patient 6-12 hrs Preferred ed with a low likelihood of functional recovery period STEP 2: Check blood glucose (BG) and then glucose load Standard following revascularization. IF: fasting BG < ~ 250 mg/dL* → oral glucose loading (25-100 g orally) c. Partially reduced myocardial perfusion with IF: fasting BG >~ 250 mg/dL* → no glucose loading necessary concordant FDG uptake is a non-transmural STEP 3: Insulin administration (see Table 2) Standard match pattern representing non-transmural scar. This pattern is unlikely to recover function unless there is associated stress-induced reversibility. FDG STEP 4: Administer 5-15 mCi of FDG if blood glucose is <150 mg/dL (preferable) Standard injection REPORTING 1. A comprehensive FDG report includes distinct sec- Begin STEP 5: Imaging acquisition Standard tions on demographics, methods, findings, and conclu- PET IF: quantification of glucose rate is desirable: initiate imaging immediately Standard sions as shown in Table 4. imaging following FDG injection (dynamic or list mode) (>10%) reversible perfusion defects will likely benefit 2. The conclusions typically include a statement about IF: qualitative analysis assessment is desirable: initiate imaging 45-90 minutes Standard from revascularization. When possible, the rest/stress per- the estimated likelihood of recovery of function (e.g., after FDG injection (use gating whenever feasible) fusion images should be interpreted prior to initiating low, intermediate, or high) following adequate revas- the FDG study because if there are moderate-to-large cularization to the jeopardized segments. This state- Check STEP 6: Image quality assessment Standard reversible perfusion defects or normal rest perfusion, ment should be based on integrating all pertinent image If increased blood pool activity is present in the images, additional IV insulin then the need for FDG PET imaging may be obviated. information from the study—including not only the quality may be administered and FDG images can be reacquired 20-30 minutes later 3. If myocardial perfusion SPECT was performed with- *250 mg/dL = 13.9 mmol/L out attenuation correction or gating, consider obtain- ing another resting perfusion study with Rubidium-82 Figure 1. Patterns of perfusion and metabolism Table 2. Guidelines for blood glucose maintenance (e.g., after oral glucose administration) or N-13 ammonia PET to ensure that the SPECT Myocardial perfusion using Rubidium-82 (left) and myocardial FDG perfusion defects are not artifactual from soft-tissue uptake (right) in the corresponding segments. BG at 45-90 minutes after administration Possible restorative measure attenuation. If PET MPI is not available, SPECT Perfusion Metabolism perfusion images should be interpreted in conjunction 130-140 mg/dL (7.22-7.78 mmol/L) 1U regular insulin IV* with regional wall motion assessment to ensure that attenuation artifacts are not interpreted as perfusion 140-160 mg/dL (7.78-8.89 mmol/L) 2U regular insulin IV defects. When available, correlation with ventricular Mismatch: function assessment by other modalities such as Hibernation echocardiography or cardiac magnetic resonance 160-180 mg/dL (8.89-10 mmol/L) 3U regular insulin IV imaging may also be useful. 4. FDG PET acquisition parameters are described