Hexamethylpropylene Amine Oxime Brain Single-photon Research Articles

Cerebral Hyperperfusion After Carotid Stenting: A Transcranial Doppler and SPECT Study

To document the incidence of symptomatic cerebral hyperperfusion after carotid stenting and to determine possible predisposing factors. A prospective study of 29 consecutive patients undergoing carotid stenting. All patients underwent 1) brain computed tomography scan and magnetic resonance imaging, 2) transcranial Doppler including assessment of cerebrovascular reactivity of the ipsilateral middle cerebral artery and 3) 99m hexamethyl-propyleneamine oxime brain single photon emission computed tomography, before and after the procedure. A total of 5 patients developed adverse neurological events, 4 of them transient. Cerebral hyperperfusion was documented in two of these (6.9%). Both had exhausted cerebrovascular reactivity in the preoperative transcranial Doppler examination. No consistent pattern of interhemispheric asymmetry in brain perfusion was found in these patients. Symptomatic cerebral hyperperfusion is not uncommon after carotid stenting. There seems to be a link between exhausted cerebrovascular reactivity of the ipsilateral middle cerebral artery and increased risk of cerebral hyperperfusion.

Spontaneous Periodic Hypothermia and Hyperhidrosis

We present a patient diagnosed with Shapiro syndrome without corpus callosum agenesis. A 4-year-old-girl was admitted to the hospital with complaints of sweating, cooling, and drowsiness that continued during the last week of her admission. Attacks occurred almost daily, and lasted for about 1 hour. All laboratory findings, as well as Holter and echocardiography results, were normal. Cranial magnetic resonance imaging demonstrated an intact corpus callosum, and electroencephalography obtained during an attack revealed normal findings. However, technetium 99m-labeled hexamethylpropylene amine oxime brain single-photon emission computed tomography indicated increased perfusion in the right thalamus, basal ganglia, and inferior frontal areas during a hypothermic period. Although oxcarbazepine reduced the frequency of attacks, they were not halted completely. The patient responded better to carbamazepine.

Interhemispheric Asymmetry in Brain Perfusion Before and After Carotid Stenting:A99mTc-HMPAO SPECT Study

To assess the effect of unilateral carotid angioplasty and stenting (CAS) on cerebral perfusion asymmetry in patients with severe extracranial carotid stenosis by means of technetium Tc 99m hexamethyl-propyleneamine oxime brain single photon emission computed tomography ((99m)Tc-HMPAO SPECT). Twenty-nine consecutive patients (22 men; median age 68 years, range 58-80; 13 symptomatic) undergoing unilateral CAS were included in the study. Brain perfusion was assessed by (99m)Tc-HMPAO brain SPECT prior to the procedure and postoperatively at 8 hours and at 2 to 4 months. The asymmetry index (AI), a measure of the interhemispheric asymmetry in perfusion, was calculated as [(counts in "healthy" hemisphere-counts in hemisphere with carotid stenosis)/counts in "healthy" hemisphere]x100. The preoperative AI demonstrated a wide variation (mean -0.5%+/-8.4%, range -19.5% to 14.1%). There was no significant correlation between the degree of carotid stenosis and preoperative AI. The mean preoperative AI in the asymptomatic patients was lower than in the symptomatic group [-4.0%+/-8.5% (range -19.5% to 8.2%) versus 3.8%+/-6.4% (range -5.2% to 14.1%), p=0.01], suggesting reduced perfusion of the ipsilateral cerebral hemisphere compared to the contralateral side in symptomatic patients. AI variation did not improve after CAS; there was no difference in AI among the 3 SPECT studies (p=0.75). Preoperative AI correlated significantly with late AI (r=0.74, p<0.0001); however, there was no statistically significant correlation between immediate postoperative AI and either preoperative (r=0.24, p=0.217) or late (r=0.24, p=0.249) AI. Asymmetry in cerebral perfusion in patients with severe extracranial carotid atherosclerosis does not correlate with the degree of carotid stenosis. Symptomatic patients demonstrate compromised perfusion of the ipsilateral hemisphere compared to asymptomatic patients. As judged by (99m)Tc-HMPAO SPECT scanning, cerebral perfusion patterns do not significantly change after CAS.

Correlation of magnetic resonance imaging findings with hexamethylpropyleneamine oxime brain single photon emission computed tomography in ischemic stroke patients in the subacute stage

To evaluate the correlation between magnetic resonance imaging (MRI) findings and 99mTc-hexamethylpropyleneamine oxime (HMPAO) brain single photon emission computed tomography (SPECT) during the subacute stage in ischemic stroke patients. The T1 and T2-weighted images and brain SPECT findings of 84 patients (mean age 60.69 +/- 12.47 years) with subacute cerebral ischemia during the period 1998-2004 were reviewed. All HMPAO SPECT and MRI studies were performed between 3 and 7 days (mean time delay 4.76 +/- 1.29 days) after the onset of stroke symptoms. An ischemic lesion was seen both in T1 and T2-weighted images with perfusion defects above 60% (severe defect) according to count/pixel data of the lesion in HMPAO SPECT studies in 30 (90.9%) of 33 patients. Otherwise, the ischemic lesion was seen only on T2-weighted images with perfusion defects between 30% and 60% (moderate defect) in HMPAO SPECT studies in 25 (89.3%) of 28 patients. In 20 (87%) of 23 patients who had perfusion defects below 30% (mild defect) on HMPAO SPECT, only non-specific findings such as cerebral atrophy and/or periventricular ischemic-gliotic lesions could be seen in MRI. The difference between these ratios was statistically significant (P < 0.01). Brain 99mTc-HMPAO SPECT findings indicate good correlation with MRI findings. When the ischemic lesions could be seen in both T1 and T2-weighted images, the patients frequently had severe perfusion defects. When only seen in T2-weighted images, the perfusion defect was moderate. When only non-specific findings were revealed by MRI, only mild perfusion defects were found by SPECT.

The evolution of cerebral perfusion abnormalities in lewy body disease: Assessment with Tc-99m hexamethylpropylene amineoxime single photon emission computed tomography

A 42-YEAR-OLD MAN complained of visual hallucinations for several weeks. His cognitive function tests and mental scores were in the normal range. A computed tomography (CT) scan, magnetic resonance imaging (MRI) scan, and electroencephalogram showed no abnormal findings. A baseline Tc-99m hexamethylpropylene amineoxime brain single photon emission computed tomography (SPECT) (Fig 1) showed only minimal decrease in parieto-occipital perfusion. In the ensuing 12 months, the patient developed extrapyramidal signs and a cognitive decline. His condition deteriorated further in the following 6 months, and he had difficulty in walking and in daily activities. He continued to experience visual hallucinations, and his cognitive and mental tests showed a clear decline. Antipsychotic medications made his condition worse. The patient was subsequently diagnosed with Lewy Body disease (LBD). CT scan, MRI, and electroencephalogram were still normal. A follow-up SPECT study 18 months later showed markedly diminished posterior cortical perfusion (Fig 2). Cerebral blood flow abnormalities in LBD might reflect a combination of direct cortical disease and cortical deafferentiation secondary to subcortical Lewy body pathology. ~ LBD is commonly associated with bilateral posterior cortical blood flow abnormality, ~-4 a pattern that is difficult to differentiate from Alzheimer's disease (AD). Nonetheless, the striking abnormality in the occipital cortex of this patient is atypical of early AD, and the clinical follow-up confirmed the diagnosis of LBD. The accurate clinical differentiation of LBD and AD is important with regard to patient management and long-term prognosis. Most of the reports pertaining to cerebral perfusion findings in patients with dementia do not describe the follow-up of these patients and the evolution of perfusion abnormalities associated with continuous mental deterioration. The pattern and progression of cerebral blood flow abnormalities in patients diagnosed with LBD is essential to further characterize the disorder and the profile of clinical findings. It may also aid in the critical evaluation of future therapies. Possible differential diagnoses for this patient are listed in the following section.

Evaluation of dysthymic disorder with technetium-99 m hexamethylpropylene amine oxime brain single-photon emission tomography.

Dysthymic disorder is a chronic disorder characterised by the presence of a depressed mood and is classified as a distinct category in DSM-IV, separately from major depression. Although brain imaging studies have been performed in major depressive disease, there have to date been no reports of such studies in dysthymic disorder. In this study 36 patients with dysthymic disorder were compared with 16 normal subjects using technetium-99m hexamethylpropylene amine oxime brain single-photon emission tomography. A relative blood flow ratio was calculated for each region of interest using the average tissue activity in the region divided by activity in the cerebellum. There were significant differences in the bilateral inferior frontal, bilateral parietal, right superior frontal and left posterior temporal regions in the patients with dysthymic disorder compared with the healthy controls. These findings support the hypothesis that the biological bases for dysthymic disorder and major depression are similar. Recognition of these regional abnormalities may have clinical utility in both the diagnosis and the treatment of dysthymic disorder. Further studies are needed to confirm our results and to assess the influence of treatment in patients with dysthymic disorder.

A technetium-99m hexamethylpropylene amine oxime brain single-photon emission tomography study in adolescent patients with major depressive disorder.

We have not encountered any brain single-photon emission tomography (SPET) study performed in adolescent depressed patients in the literature. Therefore, we used technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) brain SPET in adolescent patients with major depressive disorder (MDD) to examine the possible changes in cerebral perfusion and the possible association between perfusion indices and clinical variables. Fourteen adolescent out-patients (nine females, five males; mean+/-SD age: 13.11+/-1.43 years; range: 11-15 years) fulfilling the DSM-IV criteria for MDD and 11 age-matched healthy control subjects (six females, five males; mean+/-SD age: 13.80+/-1.60 years; range: 12-15 years) were included in the study. 99Tc-HMPAO brain SPET was performed twice in the patient group and once in the control group. The first SPET investigation was performed under non-medicated conditions and the second was performed after depressive symptoms had subsided. A relative perfusion index (PI) was calculated as the ratio of regional cortical activity to the whole brain activity. We found significant differences between the PI values of the untreated depressed patients and those of the controls, indicating relatively reduced perfusion in the left anterofrontal and left temporal cortical areas. No significant differences in regional PI values were found between the remitted depressed patients and the controls. Our study suggests that adolescent patients with MDD may have regional cerebral blood flow deficits in frontal regions and a greater anterofrontal right-left perfusion asymmetry compared with normal subjects. The fact that these abnormalities in perfusion indices have a trend toward normal values with symptomatic improvement suggests that they may be state-dependent markers for adolescent MDD.