Cerebral perfusion scintigraphy study as confirmation test of brain

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Special collaboration
Cerebral perfusion scintigraphy study as confirmation test of brain death in the
process of organ donation for transplant夽
El estudio gammagráfico de perfusión cerebral como prueba de confirmación de muerte
encefálica en el proceso de donación de órganos para trasplante
J. Banzo a,∗ , P. Razola a , J.J. Araíz b , J. Larraga b , L. Tardín a , A. Andrés a , A. Santapau a , A. Parra a ,
E. Rambalde a , S. Ayala a , E. Prats a
a
b
Servicio de Medicina Nuclear, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
Unidad de Cuidados Intensivos, Coordinación de trasplantes, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
“Death is a human cultural event as are the criteria of death. It is
man who says what is life and what is death and elaborates definitions which may change with time. Ethicists and physicians
may educate society on the scientifically safe and philosophically defendable conceptions of death, but where to draw the line
of separation between life and death is a decision which must
be made by society as a whole and be regulated by legislation
and social principles.”
D. Gracia. Vida y muerte: Bioética en el trasplante de órganos.
1995 (Life and death: bioethics of organ transplantation).
Introduction
Until the introduction of life support measures at the end of the
1950s the close interrelation between encephalic, respiratory and
cardiac functions was such that the discontinuation of one of these
functions entailed the interruption of the others. The constitution
of intensive care units (ICU) demonstrated that the classical criteria
defining death as irreversible cardiorespiratory arrest was not adequate in patients with irreversible cerebral and encephalic trunk
lesions connected to life support systems. In this new scenario the
concept of death had to be redefined, with the Ad Hoc Committee
of the Harvard Medical School introducing the term brain death in
the medical terminology,1 which has currently been substituted by
encephalic death (ED). On the other hand, the technological advances allowing organ transplantation almost simultaneously led to
the need for obtaining viable organs from donors who had died
without reaching irreversible cardiorespiratory arrest. The legal
definition of death had to be modified, elaborating criteria based
on “the definitive loss of all the vital neurological signs”: arreactive
coma, absence of encephalic trunk reflexes and apnea.2 ED is scientifically recognized as the death of the individual and is accepted
as such in the legislations of different countries including Spain.
According to data published by the Transplant Working Group of
the Spanish Society of Critical Intensive Care Medicine and Coronary Units (SEMICYUC),3 14% of the patients who die in the ICU
do so within a setting of ED, rising to 30% if the ICU is a reference
夽 Please cite this article as: Banzo J, et al. El estudio gammagráfico de perfusión
cerebral como prueba de confirmación de muerte encefálica en el proceso de donación de órganos para trasplante. Rev Esp Med Nucl Imagen Mol. 2012;31(5):278–85.
∗ Corresponding author.
E-mail address: [email protected] (J. Banzo).
center for neurosurgery. The most frequent causes leading to ED
are hemorrhagic cerebrovascular accidents and cranioencephalic
traumatisms.4
Annex I of the Real Decreto (RD) 2070/19995 of December 30
regulates the activities of clinical obtainment and use of human
organs and territorial coordination of matters of organ and tissue
donation and transplantation and establishes the diagnostic protocols and certification of death for the extraction of organs from dead
donors. Cerebral perfusion scintigraphy with lipophilic tracers able
to pass through the intact blood–brain barrier is included as the instrumental test of diagnostic support to evaluate cerebral blood flow
(CBF) together with cerebral arteriography, cerebral angiography
by digital subtraction and transcranial Doppler sonography (TDS).
Protocol of cerebral perfusion scintigraphy: technical
aspects
Patients
The clinical diagnosis of ED should be previously established
by complete, systematic neurological examination together with
atropine and apnea tests. The patients should be hemodynamically stable and not require the interruption of any therapy regimen.
During transfer to the Department of Nuclear Medicine (NM) and
while planar images are acquired the vital signs must be constantly
monitored and mechanical ventilation must be supervised by ICU
staff. Prior to initiation of the cerebral perfusion scintigraphy study
(CPSS) information should be obtained in all the cases as to the
cause of the coma, the situation of the cardiorespiratory function
parameters, the presence or not of soft tissue head lesions secondary to traumatism or recent surgery, the situation of the catheter
to measure intracranial pressure, when present, and identification,
with aid from ICU nursing personnel, of the most adequate venous
via for administration of the tracer.
Image acquisition
Injection of the tracer
Both 99m Tc-HMPAO (hexamethyl propylene amine oxime) and
(ethyl cysteinate dimer) are accepted as biomarkers
of cerebral perfusion6,7 and may be used in the diagnosis of
confirmation of ED, although there is greater experience with the
former. While the American Academy of Neurology (AAN) only
99m Tc-ECD
2253-8089/$ – see front matter © 2012 Elsevier España, S.L. and SEMNIM. All rights reserved.
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recommends the use of 99m Tc-HMPAO, the American College of
Radiology (ACR) and the Society of Nuclear Medicine (SNM) recommend both of the biomarkers of cerebral perfusion indistinctly.8
In the above-mentioned RD it is specified that the scintigraphic examination must be performed with “radiotracers able to
pass the blood–brain barrier”. The use of unspecific tracers such
as 99m Tc-DTPA (diehyilenetriaminopentaacetic acid) or 99m TcGH (glucoheptonate) is not currently justified. Quality control is
mandatory and must determine the efficacy of the labeling by chromatography and should also take into account the stability of the
radiotracer preparation. In the particular case of 99m Tc-HMPAO
the labeled preparation is eliminated with a lipophilic fraction
less than 85%. In our department we use a fixed dose of nonstabilized (925 MBq) 99m Tc-HMPAO in adults which is prepared
immediately before administration. The dose in children is calculated following the recommendations of the European Association
of Nuclear Medicine.9 Injection of the tracer is performed in a bolus
through a central vein immediately followed by a 10 cc injection of
physiological saline.
Cerebral angioscintigraphy and planar images
The dynamic cerebral study is acquired in anterior projection
centering the head of the patient slightly flexed on the axial plane of
the collimator so that the plane passes through the external angles
of the orbits and both external auditory tubes are perpendicular to
the plane of the detector. The field of examination should include
the head, the neck and the upper third of the thorax. The duration of
the dynamic study is 60 s (1 image/s in a matrix 64 × 64) from the
instant that the tracer reaches the aortic arch. Immediately after
completing the dynamic study the planar images are obtained in
anterior, right lateral and left lateral projections with an acquisition
time of less than 120 s/image in a matrix of 256 × 256. To acquire the
images in lateral projection the head of the patient is turned from
the anterior position to situate the sagittal plane of the head parallel
to the plane of the collimator continuously controlling the situation
of the endotracheal tube. If the external ear makes interpretation of some of the lateral images difficult, they may be repeated
by folding the ear forward. We do not recommend systematic
SPECT.
Evolutive scintigraphic studies
In patients in which the CPSS shows persistence of CBF and
therefore does not confirm the clinical diagnosis of ED a second
CPSS may be carried out after 15 h. Prior to administration of
the tracer it is advisable to acquire at least one planar image to
know the intensity of the residual hemispheric and/or cerebellous activity resulting from the previous CPSS. When the interval
between the first and second CPSS is 15 and 24 h, the dose of
the tracer should be increased 20% with respect to the standard
dose.
Decision making
In cases in which the clinical diagnosis of ED is confirmed by
CPSS, the NM specialist responsible for the study certifies the death
of the patient together with the neurologist or neurosurgeon and
the intensive care specialist. If the patient is an organ donor the
transplant coordinator activates the donation procedure while the
life support measures are withdrawn in cases which are not donors.
When the CPSS does not confirm the diagnosis of ED the support measures remain unvariable in the ICU. Table 1 shows the
procedure followed in the clinical diagnosis of irreversible coma
in a possible organ transplant donor.
279
Legal aspects
The diagnosis and certification of ED is of great clinical relevance in the modern health care system in both the cases of organ
donation and those not involving donation. The first case allows
the availability of viable organs for transplantation, and the second
facilitates the withdrawal of all life support measures thereby shortening the time of familial uncertainty and suffering as well as
avoiding the sensation of useless effort and pressure on the health
care personnel. The Candanchú Report,10 endorsed by the Spanish
Society of Neurology, on the neurological diagnosis of brain death
states that “suppression of all artificial maintenance of functions
is justified after the signing of the death certificate”. The patient
does not die as a consequence of the withdrawal of reanimation,
and health care is interrupted because the patient is dead. There
are not, therefore, two different criteria of the diagnosis of death,
one for the organ donor and another for the non-donor; the same
criterion is used for two different actions. The promotion of the
RD 2070/19995 represented a notable legislative advance compared with the previous RD 426/1980,11 with incorporation, among
other things, of the latest scientific advances in the diagnosis of
ED. This facilitated the clinical work of the Departments of NM
which, as in our case, had been applying scintigraphic techniques
in the diagnosis of ED for many years. Escudero et al.4 compared
the content of the two RD and noted the contributions of the RD
2070/19995 : 1. Define death following cardiorespiratory and neurological criteria so that the diagnosis and certification of death
is based on the confirmation of irreversible cessation of both cardiorespiratory (death by cardiorespiratory arrest) and encephalic
(ED) function; 2. Indicate when the hour of death should be registered; 3. Specify the primarily infratentorial disease; 4. Incorporate
updated diagnostic protocols; 5. Allow the diagnosis of ED without
instrumental tests; and 6. Include specific criteria for the pediatric
population.
Instrumental tests of diagnostic support are not always obligatory provided that the cause of the coma is known, there is
no intolerance to the apnea test, all situations which may hinder
or impede examination of encephalic trunk reflexes are excluded
such as severe destruction of the facial structure, hypothermia
less than 32 ◦ C and intoxication or previous treatment with high
doses of central nervous system depressants. However, when these
circumstances are present, there is no demonstrated destructive
cerebral lesion, the cause of coma is primarily infratentorial or there
is intolerance to the apnea test, it is obligatory to at least perform
one instrumental diagnostic support test. With respect to the observation period which is different for adults and children and variable
according to the etiology of the coma, this period may be shortened by the performance of an instrumental test with conclusive
results (Table 2). The possibility of reducing the observation period
avoids prolonged hemodynamic maintenance which may lead to
functional deterioration or the loss of organs for transplantation.
The results of a multicenter study undertaken by Escalante et al.3
showed that 6% of potential organs donors presented cardiac arrest
during the obligatory observation period. Along the same line, Lustbader et al.12 recently reported that during the 6-h interval between
the first and second neurological examination performed to certify
ED following the recommendations of the clinical guidelines elaborated by the New York State Department of Health, 12% of organ
donors were lost due to the increase in rejection to organ donation by the relatives or to the presentation of irreversible cardiac
arrest.
The
instrumental
diagnostic
support
tests
included
in
the
current
legislation
evaluate
neuronal
function
(electroencephalogram
and evoked potentials) and CBF. CPSS is among the latter group,
together with four-vessel cerebral arteriography, cerebral angio-
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280
J. Banzo et al. / Rev Esp Med Nucl Imagen Mol. 2012;31(5):278–285
Table 1
Cerebral blood flow tests in the process of organ transplant donation.
Intensive Care
(Clinical diagnosis)
- Neurological study
- Atropin test
- Apnea test
- Echo-Doppler
Nuclear Medicine
(Confirmation)
Cerebral
perfusion
Confirmation
Encephalic death
Diagnosis of
Encephalic death
graphy by digital subtraction and TDS. Different authors have
defined the qualities to be fulfilled by an ideal instrumental
diagnostic support test: availability, rapid, safe, non-invasive,
portable, without false positive results or influenced by internal
or external factors and inexpensive. Both the technical aspects
and the criteria of interpretation should be standardized. In
addition, as indicated by Zuckier and Kolano,13 the procedure
should be sufficiently robust in itself to confirm or not the clinical
diagnosis.
Cerebral perfusion scintigraphic study
Interpretation criteria
Edema and necrosis of the cerebral parenchyma induced by
catastrophic lesion of the central nervous system are the cause
of the increase in intracranial pressure and the progressive diminishment of perfusion pressure which perpetuate edema and
necrosis. Circulatory arrest at the base of the cranium is, therefore, the essential trait of ED and the techniques evaluating
CBF are the best candidates for consideration as the reference
standard.14
The technical conditions and the interpretation criteria of cerebral study with 99m Tc-HMPAO applied in the diagnosis of ED in
both adults and children were defined during the second half of the
1980s and the first years of the following decade,15–19 Posteriorly
the procedure was endorsed in different clinical guidelines elabora-
Table 2
Observational period (whenever the diagnosis of EDa is only clinical).
• Adults
- Known destructive lesion: 6 h
- Anoxic encephalopathy: 24 h
- Intoxication or treatment with
CNS depressants: >drug half life
Transplant Coordinator
(Process of donation)
• Children
- Preterm neonates: 48 h
- Neonates up to 2 months: 48 h
- Children from 2 months to
1 year: 24 h
-Children from 2 months to
1 year: 24 h
-Children from 1 to 2 years:
•Anoxic cause: 24 h
• Destructive cause: 12 h
The observation period may be shortened according to medical criteria, if a diagnostic support test with conclusive results is performed.
a
ED: encephalic death.
Donation?
Yes
No
Transplant
Procedure
Withdrawal of
life support measures
ted by recognized, prestigious professional scientific societies.8,20
Studies with 99m Tc-HMPAO progressively replaced cerebral angioscintigraphy with non-diffusible tracers (99m Tc-DTPA or 99m Tc-GH),
providing simultaneous reporting of CBF, cerebral perfusion and
functional neuronal viability. Although significant differences have
been demonstrated in the regional distribution of 99m Tc-HMPAO
and 99m Tc-ECD, it is widely recognized that CPSS with one radiotracer or another is a safe, reliable and specific study which does
not require any type of patient preparation or have any contraindications, and is also easy to perform, interpret and understand
by non-medical personnel (patient relatives and judges) provided that the procedure applied fulfills the optimum standards of
quality,13,14,21–24 The use of CPSS allows evaluation of CBF of all the
regions of the encephalus and differentiates the situation of low
versus absent cerebral blood flow. Moreover, the results are not
influenced by the conditions which hinder and limit the clinical
diagnosis of ED. Studies with diffusible tracers provide information
on functional neuronal viability. Cerebral uptake depends on the
transformation of lipophilic molecules to a hydrophilic form which
is only possible if neuronal metabolism is preserved.23
In the case of ED, angioscintigraphy demonstrates circulatory
arrest at the base of the cranium deriving the blood flow exclusively through the external carotid arteries. The planar images show
complete absence of uptake in the cerebral hemispheres, basal ganglia and cerebellum. Dynamic study and the planar images should
be evaluated together by a specialist in NM with wide experience
in interpreting CPSS following the strict criteria recommended by
the NM group of the Hospital Reina Sofía of Córdoba, Spain15,16
any intracranial parenchymatous uptake or image of unclarified doubtful interpretation rules out scintigraphic diagnosis of
ED.
The use of SPECT is controversial. Authors such as Munari
et al.25 reported that cerebral perfusion SPECT should be considered the reference standard in the diagnosis of ED while Al
Shammri and Al Feeeli26 described similar results between the
planar images and SPECT in a series of 28 patients with clinical diagnosis of ED and did not recommend routine use. It
could be argued that SPECT would facilitate the interpretation
of doubtful planar images, which are mostly related to increased
uptake in soft tissue or with anatomical variants which modify
the usual pattern of tracer biodistribution. In clinical practice
it is not difficult to identify as such any extracerebral uptake
without the need to perform SPECT (Fig. 1 of Annex 1) and, additionally, it is questionable whether SPECT allows evaluation of
encephalic trunk perfusion.8 The length of time a patient remains
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Table 3
Patients and etiology of the coma (period January 2000–August 2011).
• Patients: 305
- Women: 108
- Men: 197
- Excluded: 3a
• Age
- 1 day–86 years
• Donors: 202
• Etiology of the coma
- Cerebrovascular accident: 174
• Hemorrhagic: 145
• Ischemic: 29
- Cranioencephalic traumatism: 95
- Anoxic encephalopathy: 9
- Cerebral tumor surgery: 6
- Others: 16
- No clinical history: 2
281
Table 4
Recommendations for performing and interpreting a CPSS.
• Perform the procedure following the standard optimum quality
(radiotracer preparation and image acquisition).
• Interpret the vascular phase (dynamic study) and parenchymatous
images (planar images) together.
• Carefully evaluate the posterior fossa in the lateral projections.
• Identify any extracerebral activity.
• Interpret according to strict criteria: any intracranial parenchymatous
uptake rules out the diagnosis of encephalic death.
a
CPSS: Cerebral perfusion scintigraphic study.
One patient had a cardiac arrest few seconds after administration of the tracer.
a
In 2 patients the clinical record was not available.
in the Department of NM should be as short as possible and
if SPECT is performed, acquisition of planar images should be
avoided.27
Experience of the Department of Nuclear Medicine, HCU Lozano
Blesa
Table 3 shows the etiology of coma in 302 patients with clinical
diagnosis of ED in whom CPSS was performed during the period
from January 2000 to August 2011. Hemorrhagic cerebrovascular accidents and cranioencephalic traumatisms predominated.
The etiology of the coma was not determined in only two
patients.
The patterns of cerebral perfusion found were:
- I: absence of CBF in the dynamic study and supra- and
infratentorial uptake in the planar images in 270 patients
(Figs. 1–3 of Annex 1).
- II: CBF was not detected in the dynamic study with limited uptake
in the infratentorial compartment in the planar images in 10
patients (Figs. 2 and 3B of Annex 1).
- III: detection of CBF in the dynamic study with uptake exclusively localized in the cerebral hemispheres of 7 patients
(Figs. 4 and 5 of Annex 1).
- IV: detection of CBF with supra- and infratentorial uptake in 15
patients (Fig. 4 of Annex 1). In most of the patients with types III
and IV perfusion patterns more or less extensive uptake defects
were observed in the planar images related to destructive lesions
identified in the CT.
The clinical diagnosis of ED was confirmed and certification was
firstly initiated in the 270 patients presenting the type I pattern,
while the diagnosis of ED was not confirmed in the remaining
32 patients (10.59%) with type II, III or IV perfusion patterns.
In 23 of these 32 patients a second CPSS (Fig. 6 of Annex 1)
was performed. In 21 patients the perfusion pattern was modified to a type I pattern (Fig. 7 of Annex 1) while no changes
were observed in the other 2 patients. One of these patients
with persistence of CBF died in the ICU several days later and
the other, a full term neonate, was discharged with the diagnosis of severe anoxic encephalopathy. Of the 9 patients in whom
a second CPSS was not performed, 7 died in the ICU and 2 were
discharged, one in a persistent vegetative state and the other,
diagnosed with intracranial hemorrhage after extirpation of a
suprasellar meningioma, presented severe neurological sequelae
(Fig. 8 of Annex 1). When the interval between the first and second
CPSS was 15–24 h after the previous procedure, the residual cerebellous and/or hemispheric activity did not make interpretation
of either the dynamic study or the planar images difficult in any
case. Of the 291 patients in whom the first or the second CPSS con-
firmed the diagnosis of ED 202 were organ donors, representing
69.4%.
The results obtained show that CPSS is more sensitive than neurological examination and that the planar images are, in turn, more
sensitive than cerebral angioscintigraphy. We found discrepancies between the neurological examination and the CPSS results
in 10.59% of the patients (Fig. 6 of Annex 1). The group from the
Newark University Hospital reported similar results.17 On ruling
out situations which make neurological diagnosis difficult, it would
have to be assumed that CPSS allows identification of areas of the
cerebral parenchyma without necrosis in patients with a clinical
diagnosis of ED. These discrepancies are more often seen when the
CPSS is obtained immediately after making the clinical diagnosis. In
most of the patients with persistence of CBF who have undergone
a second CPSS, complete absence of CBF was observed at 24–48 h.
The lack of concordance between the neurological and the CPSS
has also been reported in pediatric patients and neonates.28 The
greater sensitivity of the planar images over angioscintigraphy,
in particular, to demonstrate persistence of CBF in the posterior
fossa questions the need for a dynamic study. We did not find any
patient with persistence of CBF in the angioscintigraphy presenting complete absence of uptake in the planar images. However,
in addition to not consuming extra time the dynamic study allows
confirmation that the injection of the tracer is correct. The results
published based on clinical cases, series of patients, reviews and
clinical guidelines do not provide exact knowledge of the sensitivity of CPSS, due to the inclusion of patients with factors which
hinder or make clinical diagnosis impossible. With respect to the
specificity, the study would have to be performed in patients
with destructive cerebral lesions without a clinical diagnosis of
ED.
In our institution CPSS is indicated to confirm the diagnosis of ED
in the following circumstances: 1. Lack of any previous requisite. 2.
Incomplete neurological examination. 3. Intolerance to the apnea
test. 4. Shortening of the observation period and 5. Judicial patient.
Table 4 shows the recommendations we follow and interpretation
of the study.
Strengths and limitations
CPSS is a very reliable study which provides information on
the state of encephalic perfusion in terms of neuronal viability. Performance and interpretation of the study is simple, the
results are not influenced by factors which limit, hinder or make
clinical diagnosis difficult and the images obtained remain registered in a graphic document which is easily comprehensible for
non-medical persons. The reviews published in the last years by
groups of experts coincide in pointing out that CPSS is a first
line examination and is considered the reference standard,28–33
The limitations were classically related to the need for a Department of NM with a Radiopharmacy Unit, displacement of the
patient outside the ICU and the limited timetable availability in
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J. Banzo et al. / Rev Esp Med Nucl Imagen Mol. 2012;31(5):278–285
Table 5
Circumstances invalidating or making neurological examination impossible.
Circumstances invalidating or making neurological
examination impossible
A)
B)
C)
D)
Severe destruction of the facial structure
Intolerance to the apnea test
Hypothermia < 32 ºC
Intoxication or previous treatment with drugs or
CNS depressants
E) Destructive infratentorial lesion
YES
EEG (B and C)
Blood flow test* (A,C and D)
NO
Neurological examination
Blood flow test**
*Scintigraphic study
**To shorten the observation period
the Departments of NM. Most of the hospitals with an organ
transplant program have a Department of NM and the performance of CPSS does not require specialized or sophisticated
detection equipment. The only methodological limitation is the
need to transfer the patient outside the ICU, otherwise common
to the radiological techniques evaluating cerebral perfusion. If a
portable gamma camera or a mini gamma camera used in radioguided surgery is available, it is possible to evaluate the CBF
without the need to displace the patient.34 Although the Departments of NM do not do in-hospital extra-timetable duties, in the
last decade there has been a trend to increasing the timetable
availability of these departments, particularly in the afternoon.
In our department, most of the CPSS were performed from 8
and 19 h, that is, within the work day timetable. In regard to
examinations requested outside this schedule, weekends and
holidays, an agreement may be reached with the hospital management.
Other procedures
The lack of opacity in the internal carotid arteries above the
carotid siphon, of the vertebral arteries from their penetration in
the dura mater and the lack of filling of the internal cerebral vein
are the cardinal signs to establish the diagnosis of ED by 4-vessel
cerebral arteriography. Nonetheless, despite being classically considered as the reference standard, the relative complexity of the
procedure, the possible false positive results when the intracranial pressure is not elevated above the perfusion pressure and
the potential toxicity of the contrast medium to transplantable
organs such as the kidney are factors which advise against their
systematic use.30 At present, angio-CT may be an alternative to
arteriography since it is less invasive and is widely usable, with
scarce dependence of the operator and is rapid to perform. The
lack of opacity of the cortical segments of the middle cerebral arteries and the internal cerebral veins are reliable signs to establish
the diagnosis of ED.35 False negative results have been reported in patients with anoxic encephalopathy and decompressive
craniectomy.36
Despite the recognized advantages of TDS, most authors and
institutions which have performed a critical analysis of the different instrumental tests do not recommend this as a procedure of
confirmation of ED; the results largely depend on the experience of
the operator, with false positive and negative results having been
published in 10–15% of the patients, there are limitations in the
studies of children and an optimum acoustic window is not found
in 20% of the cases,30–33 Nonetheless, despite these limitations and
whenever possible we have performed TDS prior to CPSS thereby
allowing determination of the most adequate time to carry out the
scintigraphic study.
Left lateral
Anterior.
Fig. 1. Extensive subgaleal hematoma in a patient with clinical diagnosis of encephalic death secondary to cranioencephalic traumatism. Recognition of the soft tissue lesions
facilitates the interpretation of the dynamic study and the planar images. SPECT is not required to identify the extracerebral uptake (arrows).
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Cerebral angioscintigraphy
Cerebral angioscintigraphy
No cerebral flow
(n=280)
Cerebral flow
(n=22)
Planar images
No supra-or
infra-tentorial uptake
(n=270)
Planar images
Infra-‐tentorial
uptake
(n=10)
Supra-tentorial
uptake
(n=7)
Type II pattern
Type I pattern
Supra-and
infra-tentorial uptake
(n=15)
Type III pattern
Fig. 2. Types I and II perfusion patterns observed.
Type IV pattern
Fig. 4. Types III and IV cerebral perfusion patterns observed.
Conclusions
Cerebral perfusion scintigraphic study may be the diagnostic
support test of reference for the diagnosis of confirmation of ED
in potential organ transplant donors. Although it does not replace
the clinical diagnosis it may be performed when neurological examination or the apnea test cannot be completed or to shorten the
observation period (Table 5).
Acknowledgments
Conflict of interests
Annex 1.
To Isabel De Haro, Eva María Domingo, Antonio Lastres, María
del Mar Muñoz, Ana Sebastián, Patricia Tolosana and Sonia Vicente,
Technical Specialists in Nuclear Medicine for their excellent work
in performing the cerebral perfusion scintigraphic studies.
Figs. 1–8.
The authors declare no conflict of interests.
A
Anterior
Left lateral
B
Right lateral
Anterior
Left lateral
Fig. 3. (A) Gemistocytic grade II astrocytoma. Postsurgical coma. Type I perfusion pattern. Absence of supra- and infra-tentorial uptake. (B) Severe cranioencephalic traumatism
due to traffic accident. Type II perfusion pattern. Exclusively cerebellous uptake. The importance of acquiring planar images in lateral projections is of note.
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Right lateral
Fig. 5. Cerebellous hemorrhage. Type III perfusion pattern: Persistence of blood flow in both cerebral hemispheres and absence of infratentorial uptake (arrows).
Supra-and infratentorial uptake
(n=15)
Supra-tentorial
uptake
(n=7)
Scintigraphic
control (n=23)
Death
(n=21)
Flow
(n=2)
Death
(n=1)
Infra-tentorial
uptake
(n=10)
No scintigraphic
control (n=9)
Death
(n=7)
Severe anoxic
encephalopathy
(n=1)
ICU
discharge
(n=1)
Persistent
vegetative
state
(n=1)
4 days
35 days
Fig. 6. Patients evolution (n = 32) in whom the clinical diagnosis of encephalic death
was not initially confirmed by CPSS.
B
Right lateral
Anterior
Fig. 8. Postsurgical bleeding in patients operated for suprasellar meningioma. Persistence of supra- and infra-tentorial blood flow. Right fronto-basal perfusion defect
in relation to the intraparenchymatous hemorrhage detected in the CT scan.
A
References
25 hours
C
Fig. 7. Cranioencephalic traumatism secondary to traffic accident. (A) Type II perfusion pattern: Persistence of blood flow in the infratentorial compartment. (B)
The residual cerebellous activity does not impede the interpretation of the CPSS
performed 25 h later. (C) Absence of cerebral and cerebellous uptake.
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