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As an adjunct in the diagnosis of confirmed myocardial infarction (ECG and serum enzymes positive), the incidence of false negative images has been found to be 6 percent. False negative images can also occur if made prior to 24 hours in the evolutionary phase of the infarct or after 6 days in the resolution phase. In a limited study involving 22 patients in whom the ECG was positive and serum enzymes questionable or negative, but in whom the final diagnosis of acute myocardial infarction was made, the incidence of false negative images was 23 percent. The incidence of false positive images has been found to be 7 to 9 percent. False positive images have also been reported following coronary by-pass graft surgery, in unstable angina pectoris, old myocardial infarcts and in cardiac contusions.
Preliminary reports indicate impairment of brain scans using Sodium Pertechnetate Tc99m Injection which have been preceded by a bone scan using an agent containing stannous ions. The impairment may result in false positive or false negative brain scans. It is recommended, where feasible, that brain scans precede bone imaging procedures. Alternately, a brain imaging agent such as Technetium Tc 99m Pentetate Injection may be employed.
There is currently no manufacturer warning information available for this drug.
Technetium Tc 99m Pyrophosphate Injection is a bone imaging agent used to demonstrate areas of altered osteogenesis, and a cardiac imaging agent used as an adjunct in the diagnosis of acute myocardial infarction.
Kit for the Preparation of Technetium Tc 99m Pyrophosphate Injection is a blood pool imaging agent which may be used for gated blood pool imaging and for the detection of sites of gastrointestinal bleeding. When reconstituted with sterile non-pyrogenic isotonic saline and administered intravenously 30 minutes prior to the intravenous administration of Sodium Pertechnetate Tc 99m Injection, approximately 76% of the injected radioactivity remains in the blood pool.
Kit for the Preparation of Technetium Tc 99m Pyrophosphate Injection is a multidose reaction vial which contains the sterile, non-pyrogenic, non-radioactive ingredients necessary to produce Technetium Tc 99m Pyrophosphate Injection for diagnostic use by intravenous injection.
Each 10 mL vial contains 12.0 mg of sodium pyrophosphate, 2.8 mg minimum stannous tin as stannous chloride dihydrate and 4.9 mg maximum total tin as stannous chloride dihydrate; pH is adjusted to 5.3-5.7 with hydrochloric acid prior to lyophilization. No bacteriostatic preservative is present. Sealed under nitrogen.
The chemical names are: (1) Diphosphoric acid, Ditin (2+) salt; (2) Ditin (2+) pyrophosphate (4–). The structural formula is:

When a solution of sterile, non-pyrogenic, oxidant-free isotonic Sodium Pertechnetate Tc 99m Injection U.S.P. is added to the vial, Technetium Tc 99m Pyrophosphate Injection is formed for intravenous injection.
When a solution of sterile, non-pyrogenic, isotonic saline is added to the vial, it forms
a blood pool imaging agent when Sodium Pertechnetate Tc 99m Injection is injected intravenously 30 minutes after the intravenous administration of the non-radioactive reconstituted Kit for the Preparation of Technetium Tc 99m Pyrophosphate Injection. The precise structure of Technetium Tc 99m Pyrophosphate Injection is not known at this time.
Physical Characteristics
Technetium Tc 99m decays by isomeric transition with a physical half-life of 6.02 hours.¹ The principal photon that is useful for detection and imaging studies is listed in Table 1.
|
Radiation |
Mean Percent Per Disintegration |
Mean Energy (keV) |
|
Gamma-2 |
89.07 |
140.5 |
¹Kocher DC: Radioactive decay data tables. DOE/TIC-11026: 108, 1981
External Radiation
The specific gamma ray constant for Tc 99m is 0.78 R/hr-millicurie at 1 cm. The first half-value layer is 0.017 cm of lead (Pb). A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of various thicknesses of Pb is shown in Table 2. For example, the use of a 0.25 cm thickness of Pb will attenuate the radiation emitted by a factor of about 1,000.
|
Shield Thickness |
Coefficient of |
|
0.017 |
0.5 |
|
0.08 |
10-1 |
|
0.16 |
10-2 |
|
0.25 |
10-3 |
|
0.33 |
10-4 |
To correct for physical decay of this radionuclide, the fractions that remain at selected intervals after the time of calibration are shown in Table 3.
|
Hours |
Fraction |
Hours |
Fraction |
|
0* |
1.000 |
7 |
0.447 |
|
1 |
0.891 |
8 |
0.398 |
|
2 |
0.794 |
9 |
0.355 |
|
3 |
0.708 |
10 |
0.316 |
|
4 |
0.631 |
11 |
0.282 |
|
5 |
0.562 |
12 |
0.251 |
|
6 |
0.501 |
* Calibration time