Nuclear Cardiology: Nuclear Cardiology:

82 Nuclear Cardiology, The BasicsACQUISITIONAt the present time most ERNAs are acquired by multiple-view planarimaging technique. Recently, there has been increased interest inacquiring ERNAs by SPECT technology (see chapter 9). The acquisitionparameters are given in Table 8-1. The following subsections discussthe individual acquisition parameters. Positions during acquisitionare in Table 8-2.Dose and LabelingRed blood cells can be labeled using three techniques:1. In vivo2. Modified in vivo3. In vitroFor each of these methods, stannous ion (in the form of stannouspyrophosphate) is used as a reducing agent to facilitate the binding ofpertechnetate to hemoglobin.IN VIVO LABELING(The labeling efficiency for this method is 60–70%.)• Inject 10–20 µg/kg of cold stannous pyrophosphate IV.• After 15–30 min, inject 20–30 mCi of Tc-99m pertechnetate directlyintravenously.MODIFIED IN VIVO LABELING(The labeling efficiency for this method approaches 90%.)• Inject 10–20 µg/kg of cold stannous pyrophosphate IV.• After 15–30 min draw 3 mL of venous blood into a shielded syringecontaining the anticoagulant acid-citrate-dextrose and 20–30 mCi ofTc-99m pertechnetate.• Incubate at room temperature for at least 10 min.• Re-inject radiolabeled blood into patient.IN VITRO LABELINGThe labeling efficiency for this method is >97%. Presently commercialkits (e.g., Ultratag ® ) are available that have simplified this method.Therefore, we believe, this technique is the method of choice.• Three components are required: a vial with stannous chloride dihydrate,sodium dihydrate, and sodium citrate dihydrate; a syringe I with sodiumhypochlorite; and a syringe II with citric acid monohydrate and sodiumcitrate dihydrate.