Myocardial Imaging: Technetium TC 99M Sestamibi Injection is a myocardial perfusion agent that is indicated for detecting coronary artery disease by localizing myocardial ischemia (reversible defects) and infarction (non-reversible defects), in evaluating myocardial function and developing information for use in patient management decisions. Technetium TC 99M Sestamibi evaluation of myocardial ischemia can be accomplished with rest and cardiovascular stress techniques (e.g., exercise or pharmacologic stress in accordance with the pharmacologic stress agent’s labeling).
It is usually not possible to determine the age of a myocardial infarction or to differentiate a recent myocardial infarction from ischemia.
Breast Imaging: Technetium TC 99M Sestamibi is indicated for planar imaging as a second line diagnostic drug after mammography to assist in the evaluation of breast lesions in patients with an abnormal mammogram or a palpable breast mass.
Technetium TC 99M Sestamibi is not indicated for breast cancer screening, to confirm the presence or absence of malignancy, and it is not an alternative to biopsy.
Technetium TC 99M Sestamibi Dosage and Administration
For Myocardial Imaging: The suggested dose range for I.V. administration of Technetium TC 99M Sestamibi in a single dose to be employed in the average patient (70 Kg) is 370 to 1110 MBq (10 to 30 mCi).
For Breast Imaging: The recommended dose range for I.V. administration of Technetium TC 99M Sestamibi is a single dose of 740 to 1110 MBq (20 to 30 mCi).
Image Acqusition
Breast Imaging: It is recommended that images are obtained with a table overlay to separate breast tissue from the myocardium and liver, and to exclude potential activity that may be present in the opposite breast. For lateral images, position the patient prone with the isolateral arm comfortably above the head, shoulders flat against the table, head turned to the side and relaxed, with the breast imaged pendent through an overlay cutout. The breast should not be compressed on the overlay. For anterior images, position the patient supine with both arms behind the head. For either lateral or anterior images, shield the chest and abdominal organs, or remove them from the field of view.
For complete study, sets of images should be obtained five minutes after the injection, and in the following sequence:
Beginning five minutes after the injection of Technetium TC 99M Sestamibi:
-
- • ten-minute lateral image of breast with abnormality
-
- • ten-minute lateral image of contralateral breast
-
- • ten-minute anterior image of both breasts
Radiation Dosimetry
The radiation doses to organs and tissues of an average patient (70 Kg) per 1110 MBq (30 mCi) of Technetium TC 99M Sestamibi injected intravenously are shown in Table 1.
Table 1. Radiation Absorbed Doses from Tc 99m Sestamibi
|
Estimated Radiation Absorbed Dose |
|
REST |
|
2.0 hour void |
4.8 hour void |
| Organ |
rads/30 mCi |
mGy/1110 MBq |
rads/30 mCi |
mGy/1110 MBq |
| Breasts |
0.2 |
2.0 |
0.2 |
1.9 |
| Gallbladder Wall |
2.0 |
20.0 |
2.0 |
20.0 |
| Small Intestine |
3.0 |
30.0 |
3.0 |
30.0 |
| Upper Large Intestine Wall |
5.4 |
55.5 |
5.4 |
55.5 |
| Lower Large Intestine Wall |
3.9 |
40.0 |
4.2 |
41.1 |
| Stomach Wall |
0.6 |
6.1 |
0.6 |
5.8 |
| Heart Wall |
0.5 |
5.1 |
0.5 |
4.9 |
| Kidneys |
2.0 |
20.0 |
2.0 |
20.0 |
| Liver |
0.6 |
5.8 |
0.6 |
5.7 |
| Lungs |
0.3 |
2.8 |
0.3 |
2.7 |
| Bone Surfaces |
0.7 |
6.8 |
0.7 |
6.4 |
| Thyroid |
0.7 |
7.0 |
0.7 |
2.4 |
| Ovaries |
1.5 |
15.5 |
1.6 |
15.5 |
| Testes |
0.3 |
3.4 |
0.4 |
3.9 |
| Red Marrow |
0.5 |
5.1 |
0.5 |
5.0 |
| Urinary Bladder Wall |
2.0 |
20.0 |
4.2 |
41.1 |
| Total Body |
0.5 |
4.8 |
0.5 |
4.8 |
|
STRESS |
|
2.0 hour void |
4.8 hour void |
| Organ |
rads/30 mCi |
mGy/1110 MBq |
rads/30 mCi |
mGy/1110 MBq |
| Breasts |
0.2 |
2.0 |
0.2 |
1.8 |
| Gallbladder Wall |
2.8 |
28.9 |
2.8 |
27.8 |
| Small Intestine |
2.4 |
24.4 |
2.4 |
24.4 |
| Upper Large Intestine Wall |
4.5 |
44.4 |
4.5 |
44.4 |
| Lower Large Intestine Wall |
3.3 |
32.2 |
3.3 |
32.2 |
| Stomach Wall |
0.6 |
5.3 |
0.5 |
5.2 |
| Heart Wall |
0.5 |
5.6 |
0.5 |
5.3 |
| Kidneys |
1.7 |
16.7 |
1.7 |
16.7 |
| Liver |
0.4 |
4.2 |
0.4 |
4.1 |
| Lungs |
0.3 |
2.6 |
0.2 |
2.4 |
| Bone Surfaces |
0.6 |
6.2 |
0.6 |
6.0 |
| Thyroid |
0.3 |
2.7 |
0.2 |
2.4 |
| Ovaries |
1.2 |
12.2 |
1.3 |
13.3 |
| Testes |
0.3 |
3.1 |
0.3 |
3.4 |
| Red Marrow |
0.5 |
4.6 |
0.5 |
4.4 |
| Urinary Bladder Wall |
1.5 |
15.5 |
3.0 |
30.0 |
| Total Body |
0.4 |
4.2 |
0.4 |
4.2 |
| Radiation dosimetry calculations performed by Radiation Internal Dose Information Center, Oak Ridge Institute for Science and Education, PO Box 117, Oak Ridge, TN 37831-0117, (865) 576-3448. |
Instructions for Preparation
Preparation of the Technetium TC 99M Sestamibi from the Kit for Preparation of Technetium TC 99M Sestamibi Injection is done by the following aseptic procedure:
Boiling Water Bath Procedure
a. Prior to adding the Sodium Pertechnetate Tc 99m Injection to the vial, inspect the vial carefully for the presence of damage, particularly cracks, and do not use the vial if found. Tear off a radiation symbol and attach it to the neck of the vial.
b. Waterproof gloves should be worn during the preparation procedure. Remove the plastic disc from the vial and swab the top of the vial closure with alcohol to sanitize the surface.
c. Place the vial in a suitable radiation shield with a fitted radiation cap.
d. With a sterile shielded syringe, aseptically obtain additive-free, sterile, non-pyrogenic Sodium Pertechnetate Tc 99m Injection [925 to 5550 MBq, (25 to 150 mCi)] in approximately 1 to 3 mL.
e. Aseptically add the Sodium Pertechnetate Tc 99m Injection to the vial in the lead shield. Without withdrawing the needle, remove an equal volume of headspace to maintain atmospheric pressure within the vial.
f. Shake vigorously, about 5 to 10 quick upward-downward motions.
g. Remove the vial from the lead shield and place upright in an appropriately shielded and contained boiling water bath, such that the vial is suspended above the bottom of the bath, and boil for 10 minutes. Timing for 10 minutes is begun as soon as the water begins to boil again. Do not allow the boiling water to come in contact with the aluminum crimp.
h. Remove the vial from the water bath, place in the lead shield and allow to cool for 15 minutes.
i. Using proper shielding, the vial contents should be visually inspected. Use only if the solution is clear and free of particulate matter and discoloration.
j. Assay the reaction vial using a suitable radioactivity calibration system. Record the Technetium Tc 99m concentration, total volume, assay time and date, expiration time and lot number on the radioassay information label and affix the label to the shield.
k. Store the reaction vial containing the Technetium TC 99M Sestamibi at 15 to 25°C (59 to 77°F) until use; at such time the product should be aseptically withdrawn. Technetium TC 99M Sestamibi should be used within 6 hours of preparation. The vial contains no preservative.
Note: Adherence to the above product reconstitution instructions is recommended.
The potential for cracking and significant contamination exists whenever vials containing radioactive material are heated.
This product is not to be used with the Recon-o-stat (thermal cycler) due to smaller vial size requirements of this heating device.
Product should be used within 6 hours after preparation.
Final product with radiochemical purity of at least 90% was used in the clinical trials that established safety and effectiveness. The radiochemical purity was determined by the following method.
Determination of Radiochemical Purity in Technetium TC 99M Sestamibi
- Obtain a Baker-Flex Aluminum Oxide coated, plastic TLC plate, #1 B-F, pre-cut to 2.5 cm x 7.5 cm.
- Dry the plate or plates at 100°C for 1 hour and store in a desiccator. Remove pre-dried plate from the desiccator just prior to use.
- Apply 1 drop of ethanol* using a 1 mL syringe with a 22 to 26 gauge needle, 1.5 cm from the bottom of the plate. THE SPOT SHOULD NOT BE ALLOWED TO DRY.
- Add 2 drops of Technetium TC 99M Sestamibi solution, side by side on top of the ethanol* spot. Return the plate to a desiccator and allow the sample spot to dry (typically 15 minutes).
- The TLC tank is prepared by pouring ethanol* to a depth of 3 to 4 mm. Cover the tank and let it equilibrate for ~10 minutes.
- Develop the plate in the covered TLC tank in ethanol* for a distance of 5 cm from the point of application.
- Cut the TLC plate 4 cm from the bottom and measure the Tc 99m activity in each piece by appropriate radiation detector.
- Calculate the % Tc 99m Sestamibi as:
*The ethanol used in this procedure should be 95% or greater. Absolute ethanol (99%) should remain at ≥ 95% ethanol content for one week after opening if stored tightly capped, in a cool dry place.
Dosage Forms and Strengths
Kit for the Preparation of Technetium Tc 99m Sestamibi Injection is supplied as a 10 mL vial in kits of five (5) (NDC # 45548-141-05), ten (10) (NDC # 45548-141-10) and thirty (30) (NDC # 45548-141-30), sterile and non-pyrogenic.
Prior to lyophilization the pH is between 5.3 and 5.9. The contents of the vial are lyophilized and stored under nitrogen. Store at 15 to 25 °C (59 to 77 °F) before and after reconstitution. Kit for Preparation of Technetium Tc99m Sestamibi Injection contains no preservatives. Included in each kit of five (5) vials, ten (10) vials and thirty (30) vials is a package insert and a sufficient number of vial shield labels and radiation warning labels.
This reagent kit is approved for distribution to persons licensed by the U.S. Nuclear Regulatory Commission to use byproduct material identified in 10 CFR 35.200 or under an equivalent license issued by an AgreementState.
Contraindications
None known.
Warnings and Precautions
Warnings
In studying patients in whom cardiac disease is known or suspected, care should be taken to assure continuous monitoring and treatment in accordance with safe, accepted clinical procedure. Infrequently, death has occurred 4 to 24 hours after Tc 99m Sestamibi use and is usually associated with exercise stress testing [see Warnings and Precautions (5.2)].
Pharmacologic induction of cardiovascular stress may be associated with serious adverse events such as myocardial infarction, arrhythmia, hypotension, bronchoconstriction and cerebrovascular events. Caution should be used when pharmacologic stress is selected as an alternative to exercise; it should be used when indicated and in accordance with the pharmacologic stress agent’s labeling.
Technetium TC 99M Sestamibi has been rarely associated with acute severe allergic and anaphylactic events of angioedema and generalized urticaria. In some patients the allergic symptoms developed on the second injection during Tc 99m Sestamibi imaging. Patients who receive Technetium TC 99M Sestamibi for either myocardial or breast imaging are receiving the same drug. Caution should be exercised and emergency equipment should be available when administering Technetium TC 99M Sestamibi. Also, before administering Technetium TC 99M Sestamibi Injection, patients should be asked about the possibility of allergic reactions to the drug.
General Precautions
The contents of the vial are intended only for use in the preparation of Technetium TC 99M Sestamibi and are not to be administered directly to the patient without first undergoing the preparative procedure.
Radioactive drugs must be handled with care and appropriate safety measures should be used to minimize radiation exposure to clinical personnel. Also, care should be taken to minimize radiation exposure to the patients consistent with proper patient management.
Contents of the kit before preparation are not radioactive. However, after the Sodium Pertechnetate Tc 99m Injection is added, adequate shielding of the final preparation must be maintained. The components of the kit are sterile and non-pyrogenic. It is essential to follow directions carefully and to adhere to strict aseptic procedures during preparation.
Technetium Tc 99m labeling reactions depend on maintaining the stannous ion in the reduced state. Hence, Sodium Pertechnetate Tc 99m Injection containing oxidants should not be used.
Technetium TC 99M Sestamibi should not be used more than six hours after preparation.
Radiopharmaceuticals should be used only by physicians who are qualified by training and experience in the safe use and handling of radionuclides and whose experience and training have been approved by the appropriate government agency authorized to license the use of radionuclides.
Stress testing should be performed only under the supervision of a qualified physician and in a laboratory equipped with appropriate resuscitation and support apparatus.
The most frequent exercise stress test endpoints sufficient to stop the test reported during controlled studies (two-thirds were cardiac patients) were:
-
- Fatigue 35%
-
- Dyspnea 17%
-
- Chest Pain 16%
-
- ST-depression 7%
-
- Arrhythmia 1%
Adverse Reactions
Adverse events were evaluated in 3741 adults who were evaluated in clinical studies. Of these patients, 3068 (77% men, 22% women, and 0.7% of the patients’ genders were not recorded) were in cardiac clinical trials and 673 (100% women) in breast imaging trials. Cases of angina, chest pain, and death have occurred [see Warning and Precautions (5)]. Adverse events reported at a rate of 0.5% or greater after receiving Technetium TC 99M Sestamibi administration are shown in the following table:
Table 2
| Selected Adverse Events Reported in > 0.5% of Patients Who Received Technetium TC 99M Sestamibi in Either Breast or Cardiac Clinical Studies* |
| Body System |
Breast Studies |
Cardiac Studies |
|
Women
n = 673 |
Women
n = 685 |
Men
n = 2361 |
Total
n = 3046 |
| Body as a Whole |
21 (3.1%) |
6 (0.9%) |
17 (0.7%) |
23 (0.8%) |
| Headache |
11 (1.6%) |
2 (0.3%) |
4 (0.2%) |
6 (0.2%) |
| Cardiovascular |
9 (1.3%) |
24 (3.5%) |
75 (3.2%) |
99 (3.3%) |
| Chest Pain/Angina |
0 (0%) |
18 (2.6%) |
46 (1.9%) |
64 (2.1%) |
| ST Segment Changes |
0 (0%) |
11 (1.6%) |
29 (1.2%) |
40 (1.3%) |
| Digestive System |
8 (1.2%) |
4 (0.6%) |
9 (0.4%) |
13 (0.4%) |
| Nausea |
4 (0.6%) |
1 (0.1%) |
2 (0.1%) |
3 (0.1%) |
| Special Senses |
132 (19.6%) |
62 (9.1%) |
160 (6.8%) |
222 (7.3%) |
| Taste Perversion |
129 (19.2%) |
60 (8.8%) |
157 (6.6%) |
217 (7.1%) |
| Parosmia |
8 (1.2%) |
6 (0.9%) |
10 (0.4%) |
16 (0.5%) |
| * Excludes the 22 patients whose genders were not recorded. |
In the clinical studies for breast imaging, breast pain was reported in 12 (1.7%) of the patients. In 11 of these patients the pain appears to be associated with biopsy/surgical procedures.
The following adverse reactions have been reported in ≤ 0.5% of patients: signs and symptoms consistent with seizure occurring shortly after administration of the agent; transient arthritis; angioedema, arrhythmia, dizziness, syncope, abdominal pain, vomiting, and severe hypersensitivity characterized by dyspnea, hypotension, bradycardia, asthenia, and vomiting within two hours after a second injection of Technetium TC 99M Sestamibi. A few cases of flushing, edema, injection site inflammation, dry mouth, fever, pruritus, rash, urticaria and fatigue have also been attributed to administration of the agent.
Drug Interactions
Specific drug-drug interactions have not been studied.
USE IN SPECIFIC POPULATIONS
Pregnancy Category C
Animal reproduction and teratogenicity studies have not been conducted with Technetium TC 99M Sestamibi. It is also not known whether Technetium TC 99M Sestamibi can cause fetal harm when administered to a pregnant woman or can affect reproductive capacity. There have been no studies in pregnant women. Technetium TC 99M Sestamibi should be given to a pregnant woman only if clearly needed.
Nursing Mothers
Technetium Tc 99m Pertechnetate is excreted in human milk during lactation. It is not known whether Technetium TC 99M Sestamibi is excreted in human milk. Therefore, formula feedings should be substituted for breast feedings.
Pediatric Use
Safety and effectiveness in the pediatric population have not been established.
Labeling describing pediatric studies of Technetium TC 99M Sestamibi kit is approved for Lantheus Medical Imaging's Technetium TC 99M Sestamibi kit . However due to Lantheus Medical Imaging's marketing exclusivity rights, a description of those studies does not appear in this Technetium TC 99M Sestamibi kit labeling.
Adverse events were evaluated in 609 pediatric patients from the three clinical studies described above. The frequency and the type of the adverse events were similar to the ones observed in the studies of Technetium TC 99M Sestamibi in adults. Two of the 609 had a serious adverse event: one patient received a Technetium TC 99M Sestamibi overdose but remained asymptomatic, and one patient had an asthma exacerbation following administration.
Geriatric Use
Of 3068 patients in clinical studies of Technetium TC 99M Sestamibi for myocardial imaging, 693 patients were 65 or older and 121 were 75 or older.
Of 673 patients in clinical studies of Technetium TC 99M Sestamibi for breast imaging, 138 patients were 65 or older and 30 were 75 or older.
Based on the evaluation of the frequency of adverse events and review of vital signs data, no overall differences in safety were observed between these subjects and younger subjects. Although reported clinical experience has not identified differences in response between elderly and younger patients, greater sensitivity of some older individuals cannot be ruled out.
Drug Abuse and Dependence
Controlled Substance
Not applicable.
Abuse
Not applicable.
Dependence
Not applicable.
Overdosage
The clinical consequences of overdosing with Technetium TC 99M Sestamibi are not known.
Technetium TC 99M Sestamibi Description
Each 10mL vial contains a sterile, non-pyrogenic, lyophilized mixture of:
Tetrakis (2-methoxy isobutyl isonitrile) Copper (I) tetrafluoroborate - 1 mg
Sodium Citrate Dihydrate - 2.6 mg
L-Cysteine Hydrochloride Monohydrate - 1 mg
Mannitol - 20 mg
Stannous Chloride, Dihydrate, minimum (SnCl2•2H2O) - 0.025 mg
Stannous Chloride, Dihydrate (SnCl2•2H2O) - 0.075 mg
Tin Chloride (stannous and stannic) Dihydrate, maximum (as SnCl2•2H2O) - 0.086 mg
Prior to lyophilization the pH is 5.6 to 5.7, and sodium hydroxide and/or hydrochloric acid may have been added for pH adjustment. The contents of the vial are lyophilized and stored under nitrogen.
This drug is administered by intravenous injection for diagnostic use after reconstitution with sterile, non-pyrogenic, oxidant-free Sodium Pertechnetate Tc 99m Injection. The pH of the reconstituted product is 5.5 (5.0–6.0). No bacteriostatic preservative is present.
The precise structure of the technetium complex is Tc 99m[MIBI]6 + where MIBI is 2-methoxy isobutyl isonitrile.
Tetrakis (2-methoxy isobutyl isonitrile) Copper (I) tetrafluoroborate has the following structural formula:
The molecular formula is C24H44N4O4BF4Cu, and the molecular weight is 602.98.
Physical Characteristics
Technetium Tc 99m decays by isomeric transition with a physical half-life of 6.02 hours.1 Photons that are useful for detection and imaging studies are listed below in Table 3.
Table 3. Principal Radiation Emission Date
| Radiation |
Mean %/
Disintegration |
Mean
Energy (KeV) |
| Gamma-2 |
89.07 |
140.5 |
1Kocher, David, C., Radioactive Decay Data Tables, DOE/TIC-11026, 108(1981).
External Radiation
The specific gamma ray constant for Tc 99m is 5.4 microcoulombs/Kg-MBq-hr (0.78 R/mCi-hr) at 1 cm. The first half value layer is 0.017 cm of 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 4. To facilitate control of the radiation exposure from Megabequerel (millicurie) amounts of this radionuclide, the use of a 0.25 cm thickness of Pb will attenuate the radiation emitted by a factor of 1,000.
Table 4. Radiation Attenuation by Lead Shielding
| Shield Thickness (Pb) cm |
Coefficient of Attenuation |
| 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 5.
Table 5. Physical Decay Chart; Tc 99m Half-Life 6.02 Hours
| Hours |
Fraction Remaining |
Hours |
Fraction Remaining |
| 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
Technetium TC 99M Sestamibi - Clinical Pharmacology
General
Technetium TC 99M Sestamibi is a cationic Tc 99m complex which has been found to accumulate in viable myocardial tissue in a manner analogous to that of thallous chloride TI-201. Scintigraphic images obtained in humans after the intravenous administration of the drug have been comparable to those obtained with thallous chloride TI-201 in normal and abnormal myocardial tissue.
Animal studies have shown that myocardial uptake is not blocked when the sodium pump mechanism is inhibited. Although studies of subcellular fractionation and electron micrographic analysis of heart cell aggregates suggest that Tc 99m Sestamibi cellular retention occurs specifically within the mitochondria as a result of electrostatic interactions, the clinical relevance of these findings has not been determined.
The mechanism of Tc 99m Sestamibi localization in various types of breast tissue (e.g., benign, inflammatory, malignant, fibrous) has not been established.
Pharmacokinetics
Pulmonary activity is negligible even immediately after injection. Blood clearance studies indicate that the fast clearing component clears with a t½ of 4.3 minutes at rest, and clears with a t½ of 1.6 minutes under exercise conditions. At five minutes post injection about 8% of the injected dose remains in circulation. There is less than 1% protein binding of Technetium TC 99M Sestamibi in plasma. The myocardial biological half-life is approximately six hours after a rest or exercise injection. The biological half-life for the liver is approximately 30 minutes after a rest or exercise injection. The effective half-life of clearance (which includes both the biological half-life and radionuclide decay) for the heart is approximately 3 hours, and for the liver is approximately 30 minutes, after a rest or exercise injection. The ideal imaging time reflects the best compromise between heart count rate and surrounding organ uptake.
Myocardial uptake which is coronary flow dependent is 1.2% of the injected dose at rest and 1.5% of the injected dose at exercise. Table 6 illustrates the biological clearance as well as effective clearance (which includes biological clearance and radionuclide decay) of Tc 99m Sestamibi from the heart and liver.
Table 6. Organ concentrations expressed as percentage of injected dose; data based on an average of 5 subjects at rest and 5 subjects during exercise
|
REST |
| Heart |
Liver |
| Time |
Biological |
Effective |
Biological |
Effective |
| 5 min. |
1.2 |
1.2 |
19.6 |
19.4 |
| 30 min. |
1.1 |
1.0 |
12.2 |
11.5 |
| 1 hour |
1.0 |
0.9 |
5.6 |
5.0 |
| 2 hours |
1.0 |
0.8 |
2.2 |
1.7 |
| 4 hours |
0.8 |
0.5 |
0.7 |
0.4 |
|
STRESS |
| Heart |
Liver |
| Time |
Biological |
Effective |
Biological |
Effective |
| 5 min. |
1.5 |
1.5 |
5.9 |
5.8 |
| 30 min. |
1.4 |
1.3 |
4.5 |
4.2 |
| 1 hour |
1.4 |
1.2 |
2.4 |
2.1 |
| 2 hours |
1.2 |
1.0 |
0.9 |
0.7 |
|
