CASE REPORT

Arterial Spin-Labeled Magnetic Resonance Imaging
in Hyperperfused Seizure Focus: A Case Report
Jeffrey M. Pollock, MD,* Andrew R. Deibler, MD,* Thomas G. West, MD,* Jonathan H. Burdette, MD,*
Robert A. Kraft, PhD,Þ and Joseph A. Maldjian, MD*
Abstract: We present a case of a clinically suspected cerebral
infarction that was diagnosed as a seizure focus on pulsed arterial spin
labeling. The finding of hyperperfusion with perfusion imaging
significantly impacted clinical management of the patient.
Key Words: pulsed arterial spin labeling, PASL, ASL,
hyperperfusion, seizure
(J Comput Assist Tomogr 2008;32:291Y292)

S

pin tag perfusion imaging is a predominantly research
magnetic resonance imaging (MRI) sequence for measuring quantitative cerebral blood flow. It has numerous
advantages over conventional perfusion imaging techniques,
including repeatability, absolute quantification, and the lack
of a need for intravenous contrast administration. Here, we
present an unusual case of hyperperfusion in the setting of
postictal seizure in which spin tag perfusion imaging played a
key role for proper diagnosis.

CASE REPORT
A 38-year-old man with no significant medical history presented
to the emergency department with a 2-day history of sinus drainage,
bifrontal headaches, and dizziness. He was diagnosed with diabetes.
One day after discharge, his fiancée witnessed him having a generalized
tonic-clonic seizure. The patient was started on Dilantin therapy but was
found to be neglecting the right side of his body. He was subsequently
transferred to our institution for a stroke evaluation. Examination of the
visual fields demonstrated a right homonymous hemianopsia, intact
extraocular muscles, and decreased visual acuity on the left.
The clinical service was concerned regarding a cerebral infarction, encephalitis, or an underlying mass lesion. Cerebrospinal
f luid analysis was negative. Magnetic resonance imaging of the brain
was performed using conventional sequences and multislice pulsed
arterial spin labeling (PASL). Initially, the conventional imaging was
thought to be negative for infarction, infection, and possible seizure
etiologies (Figs. 1A, B). Analysis of the PASL images showed marked
focal hyperperfusion involving the left posterior cerebral artery
distribution (Fig. 2). This refocused the conventional MRI examination
From the *Department of Radiology, Wake Forest University School of
Medicine; and †Department of Biomedical Engineering, Wake Forest
University, Winston-Salem, NC.
Received for publication June 21, 2007; accepted June 22, 2007.
Reprints: Jeffrey M. Pollock, MD, Department of Radiology, Wake Forest
University School of Medicine, Medical Center Blvd, Winston-Salem, NC
(e-mail: jpollock@wfubmc.edu).
There are no conflicts of interest, and no financial support has been provided.
This case has not been otherwise published.
Copyright * 2008 by Lippincott Williams & Wilkins

in which very subtle signal abnormalities were seen on the f luidattenuated inversion recovery and T2-weighted sequences in the left
posterior cerebral artery distribution. Findings from the diffusion and
postcontrast images were normal. Discussion with the clinical service
revealed that the patient had a witnessed seizure 1 hour before the
MRI examination. Hyperperfusion on PASL with the otherwise negative findings on conventional MRI ended the stroke evaluation and
allowed the clinical team to refocus on the seizure evaluation.
The patient was discharged home on seizure prophylaxis
with standard seizure precautions. His seizure etiology was ascribed
to the initiation of oral glycemic medications and a rapid change in
his blood glucose level. At 1-month follow-up, the patient remained
seizure-free, and all symptoms had completely resolved with full
restoration of his visual f ields.

DISCUSSION
Arterial spin-labeled perfusion MRI was first described
over a decade ago1,2 and has been an active area of research.3Y5
The main advantages of arterial spin label over conventional
bolus tracking for perfusion measurement are that it is completely
noninvasive (requires no gadolinium-based contrast to be
injected), can be repeated in the same session, and provides
absolute blood flow information (in units of milliliters per 100 g
of tissue per minute). This unique ability gives the PASL
sequence a significant advantage as compared with traditional
perfusion protocols in seizure imaging.
Nuclear medicine positron emission tomography and single
photon emission computed tomography have traditionally been
used to evaluate the patient in the interictal and ictal state. Regions
of hyperperfusion during the ictal state and hypometabolism in the

FIGURE 1. A, Axial T2-weighted image through the lateral
ventricles shows subtle increased signal within the cortex of the
left occipital lobe (arrows). B, Fluid-attenuated inversion
recovery sequence shows minimally increased signal in the
inferior cortex of the left occipital lobe (arrow).

J Comput Assist Tomogr & Volume 32, Number 2, March/April 2008

Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

291

J Comput Assist Tomogr & Volume 32, Number 2, March/April 2008

Pollock et al

FIGURE 2. Quantitative cerebral blood flow
map (milliliters per 100 g of tissue per
minute) generated from the PASL sequence
shows significant hyperperfusion (white
arrows) within the cortex of the left occipital
lobe corresponding to the subtle signal
abnormalities on the conventional MRI
sequences.

postictal state can be assessed based on radiotracer activity. Single
photon emission computed tomography hyperperfusion has also
been shown 6 hours after the seizure.6 These types of studies
require separate evaluations over multiple days and require
radiopharmaceuticals that must be prepared in advance.7,8
The PASL sequences have been studied regarding
ischemic hypoperfusion and blood flow quantification of brain
tumors, but very little research exists on regional hyperperfused
states.9Y13 The patient presented here vividly demonstrates the
capability of the PASL sequence to demonstrate regions of
hyperperfusion in the postictal state. Ordinarily, one would
expect hyperperfusion to be seen only if the PASL sequence was
performed during a seizure. However, hyperperfusion has been
shown to occur in the postictal state in the parahippocampal gyri
using T2-weighted gadolinium bolus perfusion. This finding
has been attributed to increased metabolism attempting to
restore the interictal state of neuronal excitability.14
Studies have been performed using computed tomography perfusion to show increased regional blood flow during
subtle status epilepticus, but the necessity of intravenous
contrast limits repeatability.15 The ability to repeat the PASL
sequence makes it readily amenable to implementation in the
evaluation of a seizure focus. For example, using this technique, it is possible to initiate a protocol of a baseline PASL
study with subsequent postictal PASL imaging to identify the
region of hyperperfusion or hypoperfusion corresponding
to the seizure focus. Larger studies with nuclear medicine
and surgical outcome correlation would be needed to show
the efficacy of the PASL sequence in seizure imaging.16

CONCLUSIONS
Hyperperfusion in the postictal state has been described,
but until now, a safe, nonradioactive, noncontrast, easily repeatable imaging study has not been available. As PASL becomes
more widely implemented in the clinical realm, its unique advantages over conventional perfusion studies give this MRI sequence
significant potential in the evaluation of the seizure patient.

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