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Society of Nuclear Medicine Procedure Guideline for
Brain Perfusion Single Photon Emission
Computed Tomography (SPECT) Using
Tc-99m Radiopharmaceuticals
version 2.0, approved February 7, 1999
A u t h o r s : Jack E. Juni, MD (William Beaumont Hospital, Royal Oak, MI); Alan D. Waxman, MD (Cedars Sinai Medical Center,Los Angeles, CA); Michael D. Devous, Sr., PhD (University of Texas South West Medical Center, Dallas, TX); Ronald S. Tikof-sky, PhD (College of Physicians and Surgeons of Columbia University, Harlem Hospital Affiliation, New York, NY);Masanori Ichise, MD (Mount Sinai Hospital and University of Toronto, Toronto, Ontario, Canada); Ronald L. Van Heertum,MD (Columbia-Presbyterian Medical Center, New York, NY); B. Leonard Holman, MD (Brigham and Women’s Hospital,Boston, MA); Robert F. Carretta, MD (Sutter Roseville Medical Center, Roseville, CA); and Charles C. Chen, MD (Saint Fran-cis Medical Center, Peoria, IL).
The purpose of this guideline is to assist nuclear preparation is to evaluate the patient for medicine practitioners in recommending, perform- ing, interpreting, and reporting the results of brain b. Achieve a consistent environment at the perfusion SPECT studies using Tc-99m radiophar- Place the patient in a quiet, dimly-litroom.
II. Background Information and Definitions
Single Photon Emission Computed Tomography iii. Ensure that the patient is seated or re- (SPECT) of the brain is a technique for obtaining to- mographic images of the 3-dimensional distribution iv. Place intravenous access at least 10 min of a radiopharmaceutical, which reflects regional v . Instruct the patient not to speak or read.
III. Common Indications
A . Detection and evaluation of cerebrovascular B. Information Pertinent to Performing the B. Evaluation of patients with suspected dementia C. Presurgical localization of epileptic foci Relevant patient data suggested for optimal inter- pretation of scans includes: patient history (includ- Additional indications not listed here are under ac- ing any past drug use or trauma), neurologic exam, tive evaluation, many of which appear promising psychiatric exam, mental status exam (e.g. Folstein mini-mental exam or other neuropsychologicaltest), recent morphologic imaging studies (e.g. CT, IV. Procedure
MRI), current medication and when last taken.
1. Demented patients must be closely monitored Patients should be instructed, if possible, to 2. Patients with neurologic deficits may require avoid caffeine, alcohol or other drugs known to affect cerebral blood flow (CBF).
3 . If sedation is required, it should be given af- Radiation Dosimetry in Adults
Radiopharmaceutical
Administered Activity
Organ Receiving the
Effective Dose*
L a r g e s t Radiation Dose*
ter injection of radiopharmaceutical, when more than 30 min post-reconstitution. For seizure disorders, it is important to inject the tracer as soon as possible after reconsti- b. Tc99m-HMPAO (stabilized): Tracer should and no more than four hr post-reconstitu- c. Tc99m-Bicisate (ECD): Inject tracer no a. Use fresh generator eluate (<2 hr old) for b. Do not use pertechnetate obtained from a within 2 hr post-injection to minimize radi- generator which has not been eluted for 24 Radiation Dosimetry in Children
(5 years old)
Radiopharmaceutical
Administered Activity
Effective Dose*
Organ Receiving the Largest
Radiation Dose*
( m C i / k g )
*per MBq (per mCi)1ICRP 62, page 132Treves ST. Pediatric Nuclear Medicine, 2nd edition. Springer-Verlag, 1995, p. 576.
SOCIETY OF NUCLEAR MEDICINE PROCEDURE GUIDELINES MANUAL JUNE 2002 imaging for best image quality. Images ob- ceptable if adequate counts are obtained.
tained after a 40 min delay will be inter- 8. A 128 x 128 or greater acquisition matrix 9. Use 3° or better angular sampling. Acquisi- quality. Images obtained after a 20 min de- tion pixel size should be 1/3–1/2 the ex- pected reconstructed resolution. It may be c. Imaging should be completed within 4 hr necessary to use a hardware zoom to achieve post injection if possible. Excessive delay an appropriate pixel size. Different zoom factors may be used in the x and y dimen- 5. Dosage: Adults 555–1110 MBq (15–30 mCi 10. Continuous acquisition may provide shorter total scan duration and reduced mechanical MBq/kg (0.2–0.3 mCi/kg). Minimum dose is 11. Segmentation of data acquisition into multi- 6. Quality Control: Radiochemical purity deter- ple sequential acquisitions will permit exclu- minations should be performed on each vial sion of bad data, e.g. removing segments of prior to injection using the method outlined in projection data with patient motion.
the package insert. A shortened one-step tech- 12. It is frequently useful to use detector pan and nique may also be used for Tc99m-HMPAO.
zoom capabilities to ensure that the entire brain is included in the field of view while al- lowing the detector to clear the patient’s 1. Multiple detector or other dedicated SPECT cameras generally produce results superior to single-detector general-purpose units. How- Vasodilatory challenge with acetazolamide (Di- ever, with meticulous attention to procedure, high-quality images can be produced on sin- Indication: Evaluation of cerebrovascular re- gle-detector units with appropriately longer serve in TIA, completed stroke and/or vascular scan times (5 x 106 total counts or more are de- anomalies (e.g. arterial-venous malformation) and to aid in distinguishing vascular from neu- 2. Patient should void prior to study for maxi- 3. The patient should be positioned for maxi- Contraindications: Known sulfa allergy (skin mum comfort. Minor obliquities of head ori- rash, bronchospasm, anaphylactoid reaction).
entation can be corrected in most systems May induce migraine in patients with migraine history. Generally avoided within three days of 4. The patient’s head should be lightly re- strained to facilitate patient cooperation in Various protocols have been used, including minimizing motion during acquisition. It is split-dose, two-day repeat study and dual-iso- not possible to rigidly bind the head in place.
tope techniques. The two-day repeat study tech- Patient cooperation is necessary. Sedation nique is simplest and may therefore be prefer- may be used following the injection of radio- able. Typically, the challenge portion is pharmaceutical if patient is uncooperative.
performed first. If this is normal, consideration 5. Use the smallest radius of rotation possible may be given to omitting the baseline study. If a with appropriate patient safeguards.
baseline scan is performed, allow sufficient time 6. Use of high-resolution or ultra high-resolu- for residual activity to clear (typically 24 hr).
tion collimation is recommended. All purpose collimation is not suitable. As a general rule of Dosage: Adults 1000 mg by slow iv push for thumb, use the highest resolution collimation typical patient. Children 14 mg/kg. Wait 15–20 min after administering acetazolamide before in- Fan-beam or other focused collimators are generally preferable to parallel-hole as they should be instructed to void immediately before count rates. Parallel-hole collimation is ac- beginning of image acquisition. Acquisition and processing are identical to non-acetazolamide should be assessed for the presence and de- Adverse effects: Mild vertigo, tinnitus, pares- gree of patient motion, target-to-background thesias and, rarely, nausea may be experienced.
ratio and other potential artifacts. Inspection These are generally self-limited and do not re- of the projection data in sinogram form may quire specific treatment. Patients may experience postural hypotension when arising and should be appropriately warned and assisted, if necessary.
screen rather than from film or paper copy to permit interactive adjustment of contrast, background subtraction and color table.
1. Filter all studies in 3 dimensions (x, y and z).
This can be achieved either by two-dimen- 4. Caution must be used in selecting levels of sionally prefiltering the projection data or by contrast and background subtraction. Non- applying a 3-dimensional post-filter to the re- continuous color scales may be confusing or misleading if abrupt color changes occur in 2. Low-pass (e.g., Butterworth) filters should the range of expected gray matter activity.
generally be used. Resolution recovery or spa- Thresholding, if used, must be based upon tially varying filters should be used with cau- knowledge of a normal database for specific tion, as they may produce artifacts.
radiopharmaceuticals and instruments used 3 . When possible reconstruct the e n t i r e b r a i n .
in acquiring the study. Artifacts can be cre- Use care not to exclude the cerebellum or ated when inappropriate thresholding is per- 4. Reconstruct data at highest pixel resolution, 5. Three-dimensional renderings may be useful i.e. one pixel thick. If slices are to be summed, in appreciating overall patterns of disease.
this should be done only after reconstruction Care must be exercised in choice of threshold, and oblique reorientation (if performed).
as artifactual defects are easily generated.
5. Attenuation correction should be performed 6 . Images must be evaluated in the context of in all cases unless a specific application or cir-cumstance would dictate otherwise. Use relevant structural information (CT/MRI).
shape contouring if available. Be sure that Specific attention should be paid to the ex- contour includes scalp and not just gray mat- tent of perfusion abnormalities relative to ter. Whenever possible, the surface contour chemic penumbra versus infarct) as well as to the possible effects of atrophy and partial- 6. Reformat transaxial data into at least three or- thogonal planes. Generate transverse sections 7. Epilepsy evaluation: Images must be corre- relative to a repeatable anatomic orientation lated with the relevant EEG data and clinical (e.g., AC-PC line), and coronal and sagittal observations in seizure patients. The exact sections orthogonal to the transverse. Addi- timing of tracer injection relative to observed tional sections along a plane parallel to the behavioral or electrical seizure activity must long axis of the temporal lobes are frequently be known. The scintigraphic appearance and extent of seizure foci may change dramati- cally depending on the exact timing of tracer 1. The extent of normal variability must be ap- injection relative to seizure onset. Ictal and in- preciated during scan interpretation. Substan- terictal studies should be compared for opti- tial variability may be noted between normal mal patient evaluation. Ictal studies are more individuals and between scans of a single sub-ject obtained at different times. Individual reliable for seizure foci localization.
laboratories should obtain or be familiar with 8. Interpreters should be familiar with the docu- a normal database to best interpret patient ment issued by the Ethical Subcommittee for studies. The Brain Imaging Council of the Functional Brain Imaging, a subcommittee of the SNM Brain Imaging Council (see refer- ence G, Mayberg, HS. The ethical clinical 2. Unprocessed projection images should be re- practice of functional brain imaging. J Nucl viewed in cinematic display prior to viewing SOCIETY OF NUCLEAR MEDICINE PROCEDURE GUIDELINES MANUAL JUNE 2002 Study reports should describe the extent and severity of defects, their correlation with mor- phologic and clinical abnormalities and, when relevant, a differential diagnosis and/or the sig- iii. The accumulation or reduction of ac- nificance of abnormality. It must be recognized that many patients will present with non-specific perfusion patterns which cannot be directly at- with insufficient resolution or statisti- tributed to a specific disorder or causative agent.
Care must be taken to avoid implying the exis- tence of cause and effect relationships between See Society of Nuclear Medicine Procedure Guideline scan and behavioral/neurologic abnormalities.
Each clinical report should include the fol- 1 . Presence of sedating medications at the time of 1. Indications for the study (brief synopsis) tracer injection may alter tracer distribution. If 2. Assessment of the technical quality of the scan sedation is absolutely necessary it should, (good, adequate, poor, including presence of whenever possible, be administered at least 5 patient movement, deviations from usual lab min after tracer injection. When sedation is used, record type and dosage of the sedative, 3. Description of abnormalities (including crite- and time at which sedative was administered ria for definition of abnormal, i.e. visual in- in relation to time of tracer injection.
spection criteria, regions of interest, compari- 2. Patient motion during data acquisition may son to lab database, reference paper, etc.) produce blurring of image data and may re- a. Provide a full differential diagnosis based on peer-reviewed and generally accepteddisease-specific patterns. Any interpretive V. Issues Requiring Further Clarification
statements not based on such criteriashould be explicitly identified as such.
b. As appropriate, qualify the scan interpreta- tion in the context of known clinical his- C. Coregistration techniques with MRI and CT tory, associated co-morbid conditions,medications, and other diagnostic studies(CT, MRI, EEG). Alternatively, state the VI. Concise Bibliography
limitations of the offered differential diag- Devous MD Sr. SPECT functional brain imaging. In: nosis if relevant clinical data are not avail- Kramer EL, Sanger J, eds. Clinical SPECT Imaging. Raven Press, Ltd., New York, NY 1995;97–128.
Fayad PB, Brass LM. Single-photon emission computed c . If the instrument and/or methodology used tomography in cerebrovascular disease. S t r o k e is significantly different than that which is typically used (e.g., as described in this Holman BL, Devous MD Sr. Functional brain SPECT: guideline), the differences should be explic- the emergence of a powerful clinical method. J Nucl itly stated in the report. Any limitations of the study should be explicitly described.
Holman BL, Johnson KA, Garada B, et al. The scinti- d. If a study cannot be interpreted based on graphic appearance of Alzheimer’s disease: a well-accepted criteria, the clinical report HMPAO SPECT. J Nucl Med 1992;33:181–185. Hung JC, Corlija M, Volkert WA, et al. Kinetic analysis of technetium-99m d, 1-HMPAO decomposition in aqueous media. J Nucl Med 1988;29:1568–1576. Juni JE. Taking brain SPECT seriously: reflections on re- cent clinical report in the Journal of Nuclear patient’s clinical history or behavior in Medicine. J Nucl Med 1994;35:1891– 1895. Mayberg, HS. The ethical clinical practice of functional brain imaging. J Nucl Med 1996;37: 1256–1259. Report of the Therapeutics and Technology Assess- ment Subcommittee of the American Academy of to all patients in all practice settings. The guide- Neurology. Assessment of brain SPECT. Neurology lines should not be deemed inclusive of all proper procedures or exclusive of other procedures rea- Van Heertum RL, Miller SH, Mosesson RE. SPECT sonably directed to obtaining the same results. The brain imaging in neurologic disease. Radiol Clin spectrum of patients seen in a specialized practice setting may be quite different from the spectrum Van Heertum RL, Tikofsky RS (ed). Cerebral Brain of patients seen in a more general practice setting.
SPECT Imaging. Raven Press, 2nd ed. New York The appropriateness of a procedure will depend, in part, on the prevalence of disease in the patientpopulation. In addition, the resources available tocare for patients may vary greatly from one medi- Disclaimer
cal facility to another. For these reasons, guide- The Society of Nuclear Medicine has written and approved guidelines to promote the cost-effective Advances in medicine occur at a rapid rate. The use of high-quality nuclear medicine procedures.
date of a guideline should always be considered in These generic recommendations cannot be applied determining its current applicability.

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