INTERESTING IMAGE Findings of 123I-Iomazenil SPECT During and After Stroke-Like Episodes in a Patient With MELAS Yoshiharu Taguchi, MD,* Shutaro Takashima, MD,* Kyo Noguchi, MD,Þ and Kortaro Tanaka, MD* Abstract: Reduced cortical benzodiazepine receptor binding potential in late images of 123I-iomazenil SPECT indicates neuronal damage in the cortex. We present the case of a 31-year-old woman with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) who had focal seizures in the right hand. FLAIR imaging in the ictal state revealed a high-intensity lesion in the left post-central gyrus, while 123I-iomazenil SPECT showed decreased tracer uptake in this lesion. The lesion completely disappeared on FLAIR imaging performed 1 month after the focal seizures; in contrast, 123I-iomazenil SPECT still revealed a significant decrease in tracer uptake in this lesion. Key Words: 123I-iomazenil, MELAS, stroke-like episode, neural damage (Clin Nucl Med 2014;39: e334Ye335) Received for publication January 22, 2013; revision accepted April 9, 2013. From the *Department of Neurology, Toyama University Hospital, Toyama, and †The Department of Radiology, Toyama University, Toyama, Japan. Conflicts of interest and sources of funding: none declared. Reprints: Yoshiharu Taguchi, MD, Department of Neurology, Toyama University Hospital, 2630 Sugitani, Toyama, 930-0194, Japan. E-mail: ytagu@med.u-toyama.ac.jp. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3906Ye334 e334 www.nuclearmed.com REFERENCES 1. Millet P, Graf C, Moulin M, et al. SPECT quantification of benzodiazepine receptor concentration using a dual-ligand approach. J Nucl Med. 2006;47: 783Y792. 2. Hatazawa I, Satoh T, Shimosegawa E, et al. Evaluation of cerebral infarction with iodine-123-iomazenil SPECT. J Nucl Med. 1995;36:2154Y2161. 3. 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Clinical Nuclear Medicine & Volume 39, Number 6, June 2014 Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Clinical Nuclear Medicine & Volume 39, Number 6, June 2014 123 I-Iomazenil SPECT in a Patient With MELAS FIGURE 1. 123I-iomazenil single-photon emission computed tomography (SPECT) shows the distribution of central benzodiazepine receptors in the human brain.1Y4 Reduced cortical benzodiazepine receptor binding potential in late images of 123I-iomazenil SPECT indicates neuronal damage or loss in the cerebral cortex.1Y3 A 31-year-old woman with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) presented with stroke-like episodes. She developed several convulsions and hypesthesia in the right hand and oral area, and was admitted to our department. After admission, focal seizures occurred intermittently in the right hand and oral area. Brain fluid-attenuated inversion recovery (FLAIR) MRI performed when the patient was in the ictal state revealed a high-intensity lesion in the left post-central gyrus (A). Despite anticonvulsant therapy, the convulsions in her right hand and oral area continued intermittently up to the second day. On the second day after admission, 123I-iomazenil SPECT was performed 15 minutes (early images) and 180 minutes (late images) after injecting the tracer at a dose of 167 MBq (4.5 mCi). Tracer uptake in the lesion revealed by MRI was increased and reduced on early5,6 and late images (C). Her convulsions disappeared on the third day after treatment with anticonvulsant drugs. A follow-up brain FLAIR MRI performed 1 month after the stroke-like episodes showed that the lesion in the left post-central gyrus had completely disappeared (B). However, late images of 123I-iomazenil SPECT performed at the same time revealed a significant decrease in tracer uptake in this lesion (D). The hypesthesia in her right hand continued, but the sensory disturbance caused by pinpricking improved. In the chronic phase, although the high-intensity area completely disappeared on FLAIR imaging, 123I-iomazenil SPECT revealed a persistent decrease in tracer uptake. Neuronal damage in the stroke-like lesions, which can no longer be detected by MRI, may continue even during the chronic phase of MELAS.5Y8 123I-iomazenil SPECT is, thus, considered to be very useful for assessing chronic neuronal damage after stroke-like episode in patients with MELAS. * 2013 Lippincott Williams & Wilkins www.nuclearmed.com Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. e335