ADVERSE REACTIONS SECTION.

ADVERSE REACTIONS. The following adverse reactions associated with the use of Technescan PYP have been reported: flushing, hypotension, fever, chills, nausea, vomiting, and dizziness, as well as hypersensitivity reactions such as itching and various skin rashes.

CARCINOGENESIS & MUTAGENESIS & IMPAIRMENT OF FERTILITY SECTION.

Carcinogenesis, Mutagenesis, Impairment of Fertility. No long-term animal studies have been performed to evaluate carcinogenic or mutagenic potential, or whether this drug affects fertility in males or females.

PACKAGE LABEL.PRINCIPAL DISPLAY PANEL.

PRINCIPAL DISPLAY PANEL A094V0. Technescan(TM) PYP(TM) NDC 69945-094-01(Kit for the Preparation of Technetium Tc 99m Pyrophosphate Injection)11.9 mg sodium pyrophosphate per vialMultiple-dose vial. Vial contains 11.9 mg Sodium Pyrophosphate, 3.2 mg (minimum) stannous chloride (SnCl 2o2H 2O) and 4.4 mg (maximum) total tin as stannous chloride (SnCl 2o2H 2O). Prior to lyophilization the pH is adjusted with hydrochloric acid. The pH of the prepared drug product is between 4.5 and 7.5. The contents are sealed under nitrogen. Sterile, non-pyrogenic. For intravenous use only after radiolabeling with Sodium Pertechnetate Tc 99m or reconstitution with 0.9% sodium chloride injection. Recommended Dosage: See Package Insert. Do not use Tc 99m solutions containing an oxidizing agent. Before preparation, store refrigerated at to 8C (36 to 46F). Use within hours of preparation. Rx only Manufactured by: Curium US LLC Maryland Heights, MO 63043 Made in USA CURIUM(TM)A094V0 R07/2025. Display Panel A094V0.

CLINICAL PHARMACOLOGY SECTION.

CLINICAL PHARMACOLOGY. Skeletal and Cardiac Imaging When injected intravenously, technetium Tc 99m pyrophosphate has specific affinity for areas of altered osteogenesis. It is also concentrated in the injured myocardium, primarily in areas of irreversibly damaged myocardial cells. One to hours after intravenous injection of technetium Tc 99m pyrophosphate, an estimated 40% to 50% of the injected dose is taken up by the skeleton, and approximately 0.01% to 0.02% of the injected dose is taken up per gram of acutely infarcted myocardium. Within period of hour, 10% to 11% remains in the vascular system, declining to approximately 2% to 3% 24 hours after injection. The average urinary excretion is approximately 40% of the administered dose after 24 hours.Gated Cardiac Blood Pool and Gastrointestinal Bleed Imaging Technescan PYP also has an affinity for red blood cells. When Technescan PYP reconstituted in 0.9% sodium chloride injection is administered 15 minutes to 30 minutes prior to the intravenous administration of sodium pertechnetate Tc 99m injection for red blood cell labeling, approximately 75% of the administered activity remains in the blood pool to allow imaging of the cardiac chambers. When the modified in vivo/in vitro red blood cell labeling method is used, comparable percentages of the injected radioactivity are obtained.

CONTRAINDICATIONS SECTION.

CONTRAINDICATIONS. None known.

DESCRIPTION SECTION.

DESCRIPTION. Drug Characteristics Technescan(TM) PYP(TM) (kit for the preparation of technetium Tc 99m pyrophosphate injection) is radioactive diagnostic drug for intravenous use after radiolabeling with sodium pertechnetate Tc 99m injection or after reconstitution with 0.9% sodium chloride injection in conjunction with sodium pertechnetate Tc 99m injection. Each vial contains 11.9 mg sodium pyrophosphate, 3.2 mg (minimum) stannous chloride (SnCl 2o2H 2O), and 4.4 mg (maximum) total tin expressed as stannous chloride (SnCl 2o2H 2O). Prior to lyophilization, the pH is adjusted with hydrochloric acid. The pH of the reconstituted drug is between 4.5 and 7.5. No bacteriostatic preservative is present. The vial contains sterile, non-pyrogenic, lyophilized powder packaged under nitrogen. The precise structures of the stannous-pyrophosphate and technetium Tc 99m pyrophosphate complexes are not known.

DOSAGE & ADMINISTRATION SECTION.

DOSAGE AND ADMINISTRATION. Radiation Safety Drug Handling. After radiolabeling of Technescan PYP, the reaction vial contains Technetium Tc 99m Pyrophosphate Injection. Handle Technetium Tc 99m Pyrophosphate Injection with appropriate safety measures to minimize radiation exposure. (See PRECAUTIONS, General.) Use waterproof gloves, effective radiation shielding, and other appropriate safety measures when preparing and handling Technetium Tc 99m Pyrophosphate Injection. Radiopharmaceuticals should be used by or under the control of healthcare providers who are qualified by specific training and experience in the safe use and handling of radionuclides, and whose experience and training have been approved by the appropriate governmental agency authorized to license the use of radionuclides.. Recommended Dosage, Administration, and Imaging Instructions for Skeletal and Cardiac Imaging. Dosing and Administration InstructionsThe recommended activity of Technetium Tc 99m Pyrophosphate Injection for each type of imaging is presented in Table 4.Administer Technetium Tc 99m Pyrophosphate Injection intravenously over 10 seconds to 20 seconds.Measure the patient dose with dose calibrator immediately before administration.If not contraindicated by patients condition, encourage patients to drink fluids before and after administration and void as often as possible to reduce unnecessary radiation exposure.For radiolabeling instructions, see Directions for Drug Preparation, Procedure for the Preparation of Technetium Tc 99m Pyrophosphate Injection. Table 4. Recommended Administered Activity of Technetium Tc 99m Pyrophosphate Injection for Skeletal and Cardiac Imaging in Adults IndicationActivity of Technetium Tc 99m Pyrophosphate Fraction of Vial Contents Required for Pyrophosphate Skeletal Imaging 185 MBq to 555 MBq (5 mCi to 15 mCi) 0.07 to 0.91 Cardiac Imaging 370 MBq to 555 MBq (10 mCi to 15 mCi) 0.26 to 0.45Skeletal Imaging Begin imaging hour to hours following administration. Cardiac ImagingThe patients cardiac condition should be stable before beginning the cardiac imaging procedure.Begin imaging 60 minutes to 90 minutes following administration. The acute myocardial infarct can be visualized from 24 hours to days following onset of symptoms, with maximum localization at 48 to 72 hours. Cardiac imaging should be done with gamma scintillation camera. It is recommended that images include anterior, left anterior oblique, and left lateral projections.Interference from chest wall lesions such as breast tumors and healing rib fractures can be minimized by employing the three recommended projections.. The recommended activity of Technetium Tc 99m Pyrophosphate Injection for each type of imaging is presented in Table 4.. Administer Technetium Tc 99m Pyrophosphate Injection intravenously over 10 seconds to 20 seconds.. Measure the patient dose with dose calibrator immediately before administration.. If not contraindicated by patients condition, encourage patients to drink fluids before and after administration and void as often as possible to reduce unnecessary radiation exposure.. For radiolabeling instructions, see Directions for Drug Preparation, Procedure for the Preparation of Technetium Tc 99m Pyrophosphate Injection. The patients cardiac condition should be stable before beginning the cardiac imaging procedure.. Begin imaging 60 minutes to 90 minutes following administration. The acute myocardial infarct can be visualized from 24 hours to days following onset of symptoms, with maximum localization at 48 to 72 hours. Cardiac imaging should be done with gamma scintillation camera. It is recommended that images include anterior, left anterior oblique, and left lateral projections.. Interference from chest wall lesions such as breast tumors and healing rib fractures can be minimized by employing the three recommended projections.. Recommended Dosage, Administration, and Imaging Instructions for Gated Cardiac Blood Pool and Gastrointestinal Bleed Imaging. Dose The recommended dose of Technescan PYP reconstituted in 0.9% sodium chloride injection for gated cardiac blood pool and gastrointestinal bleed imaging in adults is mL, followed by 555 MBq to 740 MBq (15 mCi to 20 mCi) of sodium pertechnetate Tc 99m injection. Administration Instructions for In Vivo RBC Labeling Methoda. Reconstitute Technescan PYP with 0.9% sodium chloride injection. (See Directions for Drug Preparation, Procedure for the Reconstitution of Technescan PYP.) b. Administer the patient dose of reconstituted Technescan PYP intravenously by direct venipuncture. Do not use heparinized catheters. (See WARNINGS.) c. Wait 15 minutes to 30 minutes.d. Administer sodium pertechnetate Tc 99m injection intravenously.Administration Instructions for Modified In Vivo/In Vitro RBC Labeling Method Using ACDa. Reconstitute Technescan PYP with 0.9% sodium chloride injection. (See Directions for Drug Preparation, Procedure for the Reconstitution of Technescan PYP.) b. Administer the patient dose of reconstituted Technescan PYP intravenously by direct venipuncture. Do not use heparinized catheters. (See WARNINGS.) c. Insert an intravenous line with 3-way stopcock in large peripheral vein and maintain the line with continuous drip of 0.9% sodium chloride injection.d. 30 minutes post-injection:Clear the line by withdrawing and discarding approximately mL of blood.Then draw approximately mL of blood into syringe containing mL preservative-free acid-citrate-dextrose (ACD) and 555 MBq to 740 MBq (15 mCi to 20 mCi) of sodium pertechnetate Tc 99m injection.Turn the stopcock, flush the line, and adjust the flow of 0.9% sodium chloride injection.e. Gently rotate syringe to mix and incubate at room temperature for 10 minutes.f. Inject the mixture via the 3-way stopcock.Administration Instructions for Modified In Vivo/In Vitro RBC Labeling Method Using Heparina. Reconstitute Technescan PYP with 0.9% sodium chloride injection. (See Directions for Drug Preparation, Procedure for the Reconstitution of Technescan PYP.) b. Administer the patient dose of reconstituted Technescan PYP intravenously by direct venipuncture. Do not use heparinized catheters. (See WARNINGS.) c. Insert an infusion set fitted with 3-way stopcock in large peripheral vein, and heparinize the intravenous line with 0.9% sodium chloride injection containing units/mL to 10 units/mL of preservative-free heparin.d. Thirty minutes after Technescan PYP injection, draw mL of blood into syringe containing 555 MBq to 740 MBq (15 mCi to 20 mCi) of sodium pertechnetate Tc 99m injection. Anticoagulation of the blood is provided by residual heparin in the intravenous line.e. Gently rotate the syringe to mix and incubate at room temperature for 10 minutes.f. Inject the mixture via the 3-way stopcock.Gated Cardiac Blood Pool Imaging Begin cardiac imaging 10 minutes following the administration of sodium pertechnetate Tc 99m injection (in vivo method) or Tc 99m labeled red blood cells (modified in vivo/in vitro method) utilizing scintillation camera interfaced to an electrocardiographic gating device. Gastrointestinal Bleed Imaging The imaging of gastrointestinal bleeding is dependent on factors such as the region of imaging, rate and volume of the bleed, efficacy of labeling of the red blood cells, and timeliness of imaging. Acquire sequential images over period of time until positive image is obtained or clinical conditions warrant the discontinuance of the procedure. The period of time for collecting the images may range up to 36 hours. Clear the line by withdrawing and discarding approximately mL of blood.. Then draw approximately mL of blood into syringe containing mL preservative-free acid-citrate-dextrose (ACD) and 555 MBq to 740 MBq (15 mCi to 20 mCi) of sodium pertechnetate Tc 99m injection.. Turn the stopcock, flush the line, and adjust the flow of 0.9% sodium chloride injection.. Directions for Drug Preparation. Procedural Precautionso The contents of the Technescan PYP reaction vial may be used for the preparation of Technetium Tc 99m Pyrophosphate Injection. Technescan PYP may also be reconstituted with preservative-free 0.9% sodium chloride injection and injected intravenously prior to labeling of red blood cells with sodium pertechnetate Tc 99m injection using either the in vivo or modified in vivo/in vitro method.o The components of the kit are sterile and non-pyrogenic. It is essential that the user follow the directions carefully and adhere to strict aseptic procedures during preparation.o Wear waterproof gloves during the entire preparation procedure and during subsequent patient dose withdrawals from the reaction vial.o Make all withdrawals and administration of sodium pertechnetate Tc 99m injection with an adequately shielded syringe.o Keep the prepared Technetium Tc 99m Pyrophosphate Injection in the lead shield described below (with cap in place) during the useful life of the radioactive preparation. Make all withdrawals and administration of the Technetium Tc 99m Pyrophosphate Injection with an adequately shielded syringe.o Any sodium pertechnetate Tc 99m injection that contains an oxidizing agent is not suitable for use in the preparation of Technetium Tc 99m Pyrophosphate Injection.Procedure for the Preparation of Technetium Tc 99m Pyrophosphate Injection1. Remove Technescan PYP reaction vial from the refrigerator and allow the vial contents to come to room temperature, 20C to 25C (68F to 77F), for approximately minutes.2. Attach the radioassay information label with radiation warning symbol to the reaction vial and place the vial in lead Dispensing Shield fitted with lead cap and having minimum wall thickness of 1/8 inch. Do not remove the reaction vial from the Dispensing Shield, except temporarily, for Step below.3. Add mL to 10 mL of sodium pertechnetate Tc 99m injection to the reaction vial. In choosing the amount of the sodium pertechnetate Tc 99m injection radioactivity to be used in the preparation of the Technetium Tc 99m Pyrophosphate Injection, the labeling efficiency, number of patients, administered radioactive dose, and radioactive decay must be taken into account. The recommended maximum activity of sodium pertechnetate Tc 99m injection to be added to the reaction vial is 3,700 MBq (100 mCi).4. With the reaction vial in the Dispensing Shield (with cap in place), shake sufficiently to bring the lyophilized material into solution. Allow to stand for minutes at room temperature.5. Using proper shielding, visually inspect the reaction vial. The resulting solution should be clear and free of particulate matter. If not, do not use the product.6. Assay the product in suitable calibrator and record the time, date of preparation, and the activity of the Technetium Tc 99m Pyrophosphate Injection onto the radioassay information label.7. Check the radiochemical purity prior to administration.8. Store the reaction vial in the Dispensing Shield at 20C to 25C (68 to 77F). Use within hours of radiolabeling.9. Dispose of unused drug in safe manner in accordance with applicable regulations.Procedure for the Reconstitution of Technescan PYPa. Remove Technescan PYP reaction vial from the refrigerator and allow the vial contents to come to room temperature, 20C to 25C (68F to 77F), for approximately minutes.b. Add mL of preservative-free 0.9% sodium chloride injection to the reaction vial.c. Shake the reaction vial sufficiently to bring the lyophilized material into solution. Allow to stand for minutes at room temperature.d. Visually inspect the reaction vial. The resulting solution should be clear and free of particulate matter. If not, do not use the product.e. Store the reconstituted reaction vial upright at 20C to 25C (68F to 77F). Use within hours of reconstitution.. Radiation Dosimetry. Skeletal and Cardiac ImagingEstimated absorbed radiation doses from an intravenous injection of Technetium Tc 99m Pyrophosphate Injection in adults are shown in Table 5.Table 5. Estimated Absorbed Radiation Doses in Organs and Tissues in Adults Who Received Technetium Tc 99m Pyrophosphate Injection Organ/Tissue Absorbed Dose per Unit Activity Administered (mGy/MBq) Skeleton0.010 Bone Marrow0.008 Kidneys0.038 Total Body0.002 Bladder 2-hr. void0.026 4.8-hr. void0.062 Testes 2-hr. void0.003 4.8-hr. void0.004 Ovaries 2-hr. void0.003 4.8-hr. void0.004 Heart Normal0.002 Impaired0.004 Dose at point of highest uptake may be factor of 10 higher.Gated Cardiac Blood Pool and Gastrointestinal Bleed Imaging Estimated absorbed radiation doses from an intravenous administration of sodium pertechnetate Tc 99m injection, 30 minutes after the intravenous administration of Technescan PYP are shown in Table 6. Table 6. Estimated Absorbed Radiation Doses in Adults Who Received Sodium Pertechnetate Tc 99m Injection 30 minutes after Technescan PYP Administration Organ/Tissue Absorbed Dose per Unit Activity Administered (mGy/MBq) Bladder Wall0.009 Ovaries0.006 Testes0.004 Red Marrow0.005 Spleen0.004 Blood0.014 Total Body0.004 Assumes non-resting state, with 75% of the sodium pertechnetate Tc 99m labeling red blood cells and the other 25% remaining as pertechnetate. Assumes no initial uptake in spleen.

DRUG INTERACTIONS SECTION.

Drug Interactions. The biodistribution of technetium Tc 99m pyrophosphate may be altered in the presence of high levels of certain cations (iron, calcium, and aluminum). This may result in reduced uptake of radionuclide in the skeleton and increased extraosseal uptake, which may potentially degrade imaging quality. In patients with high levels of these cations caused by concomitant medications, particularly patients receiving iron infusions, consider performing an imaging study with technetium Tc 99m pyrophosphate injection once the cation levels have normalized (e.g., after to half-lives of the cation). (See WARNINGS.).

GENERAL PRECAUTIONS SECTION.

General. Technetium Tc 99m pyrophosphate contributes to patients overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk of cancer. Ensure safe drug handling to protect patients and healthcare providers from unintentional radiation exposure. (See DOSAGE AND ADMINISTRATION, Radiation Safety-Drug Handling.) Advise patients to drink fluids before and after administration and to void as often as possible after administration to reduce unnecessary exposure to radiation.

GERIATRIC USE SECTION.

Geriatric Use. Of the 137 subjects included in clinical studies of Technescan PYP labeled with technetium-99m for skeletal imaging, 28 subjects (20%) were 65 to 74 years of age, and 21 (15%) were 75 years of age and older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences between elderly and younger patients.This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

HOW SUPPLIED SECTION.

HOW SUPPLIED. Technescan PYP (kit for the preparation of technetium Tc 99m pyrophosphate injection) contains 11.9 mg sodium pyrophosphate as white lyophilized powder in multiple-dose vial.Technescan PYP is available in cartons of vials (NDC 69945-094-20).Before preparation, store the Technescan PYP reaction vial refrigerated at 2C to 8C (36F to 46F).After preparation, store the vial at 20C to 25C (68F to 77F) [see USP Controlled Room Temperature]. If radiolabeled, store the vial in appropriate shielding to protect from radiation. Use within hours of preparation.Dispose of unused Technetium Tc 99m Pyrophosphate Injection in accordance with appropriate regulations.This reagent kit is for distribution to persons licensed by the U.S. Nuclear Regulatory Commission or the relevant regulatory authority of an Agreement State.Manufactured by: Curium US LLC 2703 Wagner Place Maryland Heights, MO 63043 Made in USA(C)2025 Curium US LLC. Technescan TMPYP TM, Curium TM, and the Curium logo are trademarks of Curium company. A094I0 Revised: 11/2025 CURIUM(TM).

INDICATIONS & USAGE SECTION.

INDICATIONS AND USAGE. Technescan PYP, after radiolabeling with sodium pertechnetate Tc 99m, is indicated for: Skeletal imaging to demonstrate areas of altered osteogenesis in adults Cardiac imaging as an adjunct in the diagnosis of acute myocardial infarction in adults (See WARNINGS) Technescan PYP, in conjunction with sodium pertechnetate Tc 99m injection for red blood cell (RBC) labeling, is indicated for gated cardiac blood pool imaging and for the detection of gastrointestinal bleeding sites in adults.

NURSING MOTHERS SECTION.

Nursing Mothers. Technetium-99m is excreted in human milk during lactation, therefore, formula feedings should be substituted for breast feeding.

OVERDOSAGE SECTION.

OVERDOSAGE. In case of overdose of Technetium Tc 99m Pyrophosphate Injection, encourage patients to maintain hydration and to void frequently to minimize radiation exposure.

PEDIATRIC USE SECTION.

Pediatric Use. Safety and effectiveness in pediatric patients have not been established.

PRECAUTIONS SECTION.

PRECAUTIONS. General. Technetium Tc 99m pyrophosphate contributes to patients overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk of cancer. Ensure safe drug handling to protect patients and healthcare providers from unintentional radiation exposure. (See DOSAGE AND ADMINISTRATION, Radiation Safety-Drug Handling.) Advise patients to drink fluids before and after administration and to void as often as possible after administration to reduce unnecessary exposure to radiation. Drug Interactions. The biodistribution of technetium Tc 99m pyrophosphate may be altered in the presence of high levels of certain cations (iron, calcium, and aluminum). This may result in reduced uptake of radionuclide in the skeleton and increased extraosseal uptake, which may potentially degrade imaging quality. In patients with high levels of these cations caused by concomitant medications, particularly patients receiving iron infusions, consider performing an imaging study with technetium Tc 99m pyrophosphate injection once the cation levels have normalized (e.g., after to half-lives of the cation). (See WARNINGS.) Carcinogenesis, Mutagenesis, Impairment of Fertility. No long-term animal studies have been performed to evaluate carcinogenic or mutagenic potential, or whether this drug affects fertility in males or females.. Pregnancy. Animal reproduction studies have not been conducted with Technetium Tc 99m Pyrophosphate Injection. It is also not known whether this drug can cause fetal harm when administered to pregnant woman or can affect reproduction capacity.All radiopharmaceuticals, including Technescan PYP, have the potential to cause fetal harm depending on the fetal stage of development and the magnitude of the radiation dose. If considering Technescan PYP administration to pregnant woman, inform the patient about the potential for adverse pregnancy outcomes based on the radiation dose from technetium Tc 99m pyrophosphate and the gestational timing of exposure.. Nursing Mothers. Technetium-99m is excreted in human milk during lactation, therefore, formula feedings should be substituted for breast feeding.. Pediatric Use. Safety and effectiveness in pediatric patients have not been established.. Geriatric Use. Of the 137 subjects included in clinical studies of Technescan PYP labeled with technetium-99m for skeletal imaging, 28 subjects (20%) were 65 to 74 years of age, and 21 (15%) were 75 years of age and older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences between elderly and younger patients.This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

PREGNANCY SECTION.

Pregnancy. Animal reproduction studies have not been conducted with Technetium Tc 99m Pyrophosphate Injection. It is also not known whether this drug can cause fetal harm when administered to pregnant woman or can affect reproduction capacity.All radiopharmaceuticals, including Technescan PYP, have the potential to cause fetal harm depending on the fetal stage of development and the magnitude of the radiation dose. If considering Technescan PYP administration to pregnant woman, inform the patient about the potential for adverse pregnancy outcomes based on the radiation dose from technetium Tc 99m pyrophosphate and the gestational timing of exposure.

SPL UNCLASSIFIED SECTION.

Nuclear Physical Characteristics. Technetium-99m decays by isomeric transition with physical half-life of 6.02 hours. The principal photon that is useful for detection and imaging is listed in Table 1.Table 1. Principal Radiation Emission Data Radiation Mean per Disintegration Energy (keV) Gamma-2 89.07 140.5The specific gamma ray constant for technetium-99m is 0.795 R/hr-mCi at cm. The first half-value layer is 0.023 cm of lead (Pb). 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 0.27 cm thickness of Pb will attenuate the external radiation emitted by factor of about 1,000.Table 2. Radiation Attenuation by Lead Shielding Shield Thickness (Pb) cm Coefficient of Attenuation 0.023 0.09 0.18 0.27 0.5 10 -1 10 -2 10 -3 To correct for physical decay of this radionuclide, the fractions that remain at selected time intervals after the time of calibration are shown in Table 3.Table 3. Physical Decay Chart; Technetium-99m, Half-Life 6.02 HoursCalibration Time Hours Fraction Remaining Hours Fraction Remaining 1 0.447 0.891 0.398 0.794 0.355 0.708 10 0.316 0.631 11 0.282 0.562 12 0.251 0.501.

WARNINGS SECTION.

WARNINGS. Image interpretation errors can occur. As an adjunct in the diagnosis of confirmed myocardial infarction (ECG and serum enzymes positive), the estimate of false negative image interpretations was 6%. False negative image interpretations can occur if made too early in the evolutionary phase of the infarct or too late in the resolution phase. In study involving 22 patients in whom ECG was positive and serum enzymes questionable or negative, but in whom the final diagnosis of acute myocardial infarction was made, the estimates of false negative and false positive image interpretations were 23% and 9%, respectively. False positive image interpretations have been reported following coronary artery bypass graft surgery and in unstable angina pectoris, old myocardial infarcts, and cardiac contusions.Technetium Tc 99m pyrophosphate may impair brain imaging with sodium pertechnetate Tc 99m and result in false positive or false negative image interpretation. It is recommended, where feasible, that brain imaging precede skeletal imaging procedures.Gated cardiac blood pool and gastrointestinal bleed imaging may be impaired in patients receiving sodium heparin for anticoagulant therapy. This is characterized by reduction in the amount of injected radioactivity remaining in the blood pool. Avoid heparinized catheter systems for administration of Technescan PYP.The biodistribution of technetium Tc 99m pyrophosphate may be altered in the presence of high levels of certain cations (iron, calcium, and aluminum). This may result in reduced uptake of radionuclide in the skeleton and increased extraosseal uptake, which may potentially degrade imaging quality. High levels of these cations may be caused by concomitant medications or medical conditions (e.g., iron overload, hypercalcemia, etc.). Most cases are observed after iron infusion. (See PRECAUTIONS, Drug Interactions.).