I-123 iomazenil single photon emission computed tomography for detecting loss of neuronal integrity in patients with traumatic brain injury

Kagari Abiko; Katsunori Ikoma; Tohru Shiga; Chietsugu Katoh; Kenji Hirata; Yuji Kuge; Kentaro Kobayashi; Nagara Tamaki

doi:10.1186/s13550-017-0276-1

I-123 iomazenil single photon emission computed tomography for detecting loss of neuronal integrity in patients with traumatic brain injury

EJNMMI Res. 2017 Dec;7(1):28. doi: 10.1186/s13550-017-0276-1. Epub 2017 Mar 23.

Authors

Kagari Abiko¹, Katsunori Ikoma¹, Tohru Shiga², Chietsugu Katoh³, Kenji Hirata³, Yuji Kuge⁴, Kentaro Kobayashi³, Nagara Tamaki³

Affiliations

¹ Department of Rehabilitation Medicine, Hokkaido University Hospital, Sapporo, 060-8638, Japan.
² Department of Nuclear Medicine, Hokkaido University School of Medicine, North 15th, West 7th, Kitaku, Sapporo, 060-8638, Japan. tshiga@med.hokudai.ac.jp.
³ Department of Nuclear Medicine, Hokkaido University School of Medicine, North 15th, West 7th, Kitaku, Sapporo, 060-8638, Japan.
⁴ Department of Tracer Kinetics, Hokkaido University, Sapporo, 060-8638, Japan.

Abstract

Background: Traumatic brain injury (TBI) causes brain dysfunction in many patients. Using C-11 flumazenil (FMZ) positron emission tomography (PET), we have detected and reported the loss of neuronal integrity, leading to brain dysfunction in TBI patients. Similarly to FMZ PET, I-123 iomazenil (IMZ) single photon emission computed tomography (SPECT) is widely used to determine the distribution of the benzodiazepine receptor (BZR) in the brain cortex. The purpose of this study is to examine whether IMZ SPECT is as useful as FMZ PET for evaluating the loss of neuronal integrity in TBI patients. The subjects of this study were seven patients who suffered from neurobehavioral disability. They underwent IMZ SPECT and FMZ PET. Nondisplaceable binding potential (BP_ND) was calculated from FMZ PET images. The uptake of IMZ was evaluated on the basis of lesion-to-pons ratio (LPR). The locations of low uptake levels were visually evaluated both in IMZ SPECT and FMZ PET images. We compared FMZ BP_ND and (LPR-1) of IMZ SPECT.

Results: In the visual assessment, FMZ BP_ND decreased in 11 regions. In IMZ SPECT, low uptake levels were observed in eight of the 11 regions. The rate of concordance between FMZ PET and IMZ SPECT was 72.7%. The mean values IMZ (LPR-1) (1.95 ± 1.01) was significantly lower than that of FMZ BP_ND (2.95 ± 0.80 mL/mL). There was good correlation between FMZ BP_ND and IMZ (LPR-1) (r = 0.80).

Conclusions: IMZ SPECT findings were almost the same as FMZ PET findings in TBI patients. The results indicated that IMZ SPECT is useful for evaluating the loss of neuronal integrity. Because IMZ SPECT can be performed in various facilities, IMZ SPECT may become widely adopted for evaluating the loss of neuronal integrity.