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

Abstract

BackgroundTraumatic 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 (BPND) 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 BPND and (LPR-1) of IMZ SPECT.ResultsIn the visual assessment, FMZ BPND 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 BPND (2.95 ± 0.80 mL/mL). There was good correlation between FMZ BPND and IMZ (LPR-1) (r = 0.80).ConclusionsIMZ 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.

Longitudinal alterations in gamma-aminobutyric acid (GABAA) receptor availability over ∼ 1 year following traumatic brain injury

“…The observations of focal reductions in BP ND within the frontal lobes, anterior cingulate gyrus, and the thalamus following TBI, are consistent with prior cross-sectional [ 11 C]FMZ studies. 18 , 30 , 55–57 Similarly, our findings of inter-individual variability in the BP ND are consistent with previous reports. 18 , 30 , 55 The notable differences between our study and these previous reports are as follows.…”

“… 18 , 30 , 55–57 Similarly, our findings of inter-individual variability in the BP ND are consistent with previous reports. 18 , 30 , 55 The notable differences between our study and these previous reports are as follows. Our sample spans a fuller range of TBI injury severity from complicated mild to severe compared to previous studies, 18 and patients in our study were not selected a priori by degree of cognitive impairment or cortical damage.…”

Cortical Neural Damage Associated with Cerebral Hyperperfusion after Reperfusion Therapy for Acute Ischemic Stroke: ¹²³I-iomazenil Single-photon Emission Computed Tomography Findings

“…9) A previous study showed that post-CEA hyperperfusion was significantly associated with postoperative hemispheric reduction of BRBP: ≥80% of the pixels with reduced BRBP also exhibited hyperperfusion. 10) Another study indicated that iomazenil SPECT is useful for evaluating loss of neuronal integrity in patients with traumatic brain injury without brain MRI abnormalities, 11) as MRI cannot always demonstrate selective neuronal loss. 7,[10][11][12][13] The above findings and our data indicate that CH after endovascular reperfusion therapy results in postoperative cortical neural damage, even in a region where MRI abnormalities were not found.…”

“…10) Another study indicated that iomazenil SPECT is useful for evaluating loss of neuronal integrity in patients with traumatic brain injury without brain MRI abnormalities, 11) as MRI cannot always demonstrate selective neuronal loss. 7,[10][11][12][13] The above findings and our data indicate that CH after endovascular reperfusion therapy results in postoperative cortical neural damage, even in a region where MRI abnormalities were not found. 4,5,7,10,11) However, cortical neural loss, and thus reduced BRBP on later I-123 iomazenil SPECT imaging, may have occurred secondary to hypoperfusion before reperfusion therapy if the hypoperfusion was significant enough to damage the cortical neurons.…”

“… 7 , 10 – 13) The above findings and our data indicate that CH after endovascular reperfusion therapy results in postoperative cortical neural damage, even in a region where MRI abnormalities were not found. 4 , 5 , 7 , 10 , 11) However, cortical neural loss, and thus reduced BRBP on later I-123 iomazenil SPECT imaging, may have occurred secondary to hypoperfusion before reperfusion therapy if the hypoperfusion was significant enough to damage the cortical neurons. 7) In the previous study, post-CEA hyperperfusion was significantly associated with postoperative hemispheric reduction of BRBP; the duration of internal carotid artery clamping did not correlated.…”