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Biomedical subjects

M Ichise

Publications and source records attributed to M Ichise.

53 records · Page 3Linked to original sources
PubMed1994

[In vivo characteristics of IBZM in rat brains: an agent for quantitative SPECT imaging of D2 dopamine receptors--a basis for semiquantitative measurement of the receptor density using equilibrium analysis].

To establish a basis for semiquantitative SPECT measurements of the D2 dopamine receptor density using equilibrium analysis, we evaluated in vivo kinetic properties of 125I-IBZM in rat brains. We measured percent uptakes (% dose/g) of 125I-IBZM in the striatum, frontal cortex, and cerebellum. We made these regional measurements at 15, 30, 45, 60, 90, and 120 minutes after injection, respectively. The specific striatal uptake, which is the uptake difference between striatum and frontal cortex or cerebellum, showed a transient equilibrium phase at 60 min. Theoretically, with these 'reversible' D2 receptor binding ligands, the tracer-uptake ratio of the striatum-to-frontal cortex or cerebellum during the equilibrium phase provides an estimate of binding potential (Bound/Free = Bmax/Kd). Our experiment showed that these ratio increased with time after bolus injection of the tracer. Striatum to frontal cortex or cerebellum ratios which were calculated with pooled data (n = 12) at 60 minutes in equilibrium phase showed nearly constant values (C.V. = 12.3% and 13.5%, respectively). Although measuring the striatum to frontal cortex or cerebellum ratios near equilibrium phase by bolus injection of the tracer which are widely used in human SPECT study could not exactly signify the binding potential, those ratios at fixed time after injection would be reliable for semiquantitative index.

Animals↗
PubMed1994

[In vivo characteristics of IBZM in rat brains: an agent for quantitative SPECT imaging of dopamine D2 receptors. Preparation of 125I-IBZM and its biodistribution and kinetic properties].

123I-(S)-(-)-3-iodo-2-hydroxy-6-methoxy-N-[(1-ethyl-2-pyrrolidinyl) methyl]-benzamide (IBZM) is a CNS dopamine D2 receptor imaging agent for SPECT and has already been used clinically in the United States, Canada and Europe. However, methods of quantitative SPECT measurement of the D2 receptor density have not been well established. We performed in vivo biodistribution studies of 125I-IBZM in rat brains as the first step toward establishment of a basis for quantitative SPECT imaging of D2 receptors in humans. 125I-IBZM was prepared by the chloramine-T method. Radiochemical yields were 80 to 90% and radiochemical purity was 94.7% on day 81 after labeling. At 10, 30, 60 and 120 min after injection of the radiopharmaceutical, the percent uptakes (% dose/g) in the rat striatum were 2.9, 1.9, 1.7 and 1.0, respectively. These kinetic data were considered suitable for SPECT imagings. Pretreatment with haloperidol (1 mg/kg) blocked specific striatal uptake and there was a significant reduction in the uptake to 40.9% of the unblocked uptake at 60 min after injection (p = 0.006). The regional IBZM uptake ratio of striatum-to-cerebellum increased steadily from 1.7 at 10 min to 5.7 at 120 min. This suggests that SPECT imaging must be done during fixed time after tracer injection for the semiquantitative ratio to be meaningful.

Animals↗
PubMed1994

Technetium-99m-HMPAO SPECT, CT and MRI in the evaluation of patients with chronic traumatic brain injury: a correlation with neuropsychological performance.

UNLABELLED: The purposes of this study were: (1) to compare 99mTc-hexamethylpropyleneamineoxime (HMPAO) SPECT with CT and MRI in chronic traumatic brain injury (TBI) patients and (2) to correlate both functional and structural neuroimaging measurements of brain damage with neuropsychological (NP) performance. METHODS: Twenty-nine patients (minor TBI, n = 15 and major TBI, n = 14) and 17 normal controls (NC) underwent HMPAO SPECT, CT, MRI and NP testing. Imaging data were analyzed both visually and quantitatively. RESULTS: Nineteen (66%) patients showed 42 abnormalities on SPECT images, whereas 13 (45%) and 10 (34%) patients showed 29 abnormalities on MRI and 24 abnormalities on CT. SPECT detected relatively more abnormalities than CT or MRI in the minor TBI subgroup. The TBI group showed impairment on 11 tests for memory, attention and executive function. Of these, the anterior-posterior ratio (APR) correlated with six tests, whereas the ventricle-to-brain ratio (VBR), a known structural index of a poor NP outcome, correlated with only two tests. CONCLUSION: In evaluating chronic TBI patients, HMPAO SPECT, as a complement to CT or MRI, may play a useful role by demonstrating brain dysfunction in morphologically intact brain regions and providing objective evidence for some of the impaired NP performance.

Adult↗
PubMed1993

Dopamine D2 receptor SPECT imaging: basic in vivo characteristics and clinical applications of 123I-IBZM in humans.

The purposes of this study are to evaluate the utility of kit formulation, the basic in vivo characteristics, and clinical usefulness of dopamine D2 receptor imaging with 123I-(S)-(-)-3-iodo-2-hydroxy-6-methoxy-N-[(1-ethyl-2-pyrrodinyl)m ethyl]- benzamide (123I-IBZM). We studied 22 normal controls, 3 early symptomatic Huntington's disease patients, and 1 patient with visual hallucination on and off neuroleptics. 123I-IBZM could be conveniently prepared with a high degree of purity from a kit, but with relatively low radiochemical yield. We demonstrated 123I-IBZM receptor binding equilibrium by performing serial SPECT scanning in a normal volunteer. The basal ganglia/frontal cortex (BG/FC) ratios plateaued after the specific binding reached equilibrium approximately 60 minutes after injection. The BG/FC ratio declined significantly with age. The ratios for the Huntington's disease patients were significantly lower than those for normal controls. The images of the patient off neuroleptic therapy showed dramatically increased BG activity compared with those obtained while on therapy. The BG/FC ratio provides an estimate of Bmax/Kd and hence the receptor density. It appears important to perform SPECT early in the equilibrium phase and at a fixed time after injection to obtain significantly high signal to noise ratios. 123I-IBZM is an ideal tracer for SPECT including a rotating gamma camera type which can provide estimates of the receptor density objectively by calculating the BG/FC ratio, and is a promising agent for the investigation of dopamine D2 receptors in clinical conditions.

Adult↗
PubMed1993

Iodine-123-IBZM dopamine D2 receptor and technetium-99m-HMPAO brain perfusion SPECT in the evaluation of patients with and subjects at risk for Huntington's disease.

Huntington's disease (HD) is pathologically characterized by neuronal loss and neuroreceptor alterations in the striatum, including a reduction in dopamine receptor density. We evaluated the clinical usefulness of 123I-iodobenzamide (IBZM) D2 receptor SPECT imaging and 99mTc-hexamethylpropyleneamineoxime (HMPAO) brain perfusion SPECT imaging by studying four early symptomatic HD patients, 20 asymptomatic subjects at risk for HD and 22 controls. Striatal D2 receptor binding and perfusion were measured semiquantitatively by calculating striatum-to-frontal cortex IBZM and HMPAO uptake ratios, respectively. The control IBZM ratio (1.58 +/- 0.06) declined with age at 1.5% per decade (r = -0.58, p < 0.005), whereas the HMPAO ratio (1.15 +/- 0.05) did not. All four symptomatic patients had decreased IBZM ratios and three patients also had decreased HMPAO ratios. Five of 20 at-risk subjects had decreased IBZM ratios and two subjects also had decreased HMPAO ratios. Three of the five at-risk subjects showed subtle nonchoreic neurological abnormalities. Decreased striatal D2 receptor binding thus may be detected by IBZM-SPECT in the asymptomatic as well as symptomatic groups, and these changes were more marked than perfusion deficits detected by HMPAO-SPECT. IBZM-SPECT thus appears to be a promising method for early diagnosis and preclinical detection of HD.

Adolescent↗
PubMed1992

'Reverse crescent pattern' on SPECT brain perfusion scan in chronic subdural hematoma.

A SPECT brain perfusion scan was performed on a patient who had symptoms of dementia. The SPECT scan showed marked crescentic medial displacement of the left cerebral hemisphere ("reverse crescent pattern"), and mildly decreased cortical perfusion in the affected hemisphere. Crossed cerebellar diaschisis was not present. On x-ray CT, the underlying abnormality was found to be a unilateral chronic subdural hematoma causing a significant mass effect. A reverse crescent pattern without crossed cerebellar diaschisis on SPECT brain perfusion scan in patients with dementia may suggest the diagnosis of chronic subdural hematoma.

Aged↗
PubMed1992

Neuroanatomical localization for clinical SPECT perfusion brain imaging: a practical proportional grid method.

For the purpose of facilitating anatomical localization in interpretation of 99Tcm-hexamethylpropyleneamine oxime (HMPAO) brain single photon emission tomographic (SPECT) scans, a stereotaxic proportional grid system was applied in the form of an interactive computer program. This method takes advantage of a rotating gamma camera system which permits planar scout imaging for the determination of anatomical reference lines, and standardization of tomographic slices for brain size. Using measurements made on a lateral planar HMPAO image, proportional grids were constructed onto standardized transaxial images. This method was implemented for 33 clinical HMPAO SPECT studies. It required less than 15 min of an operator's time. This simple and practical neuroanatomical localization technique can be instrumental as an aid to the interpretation of routine clinical HMPAO SPECT images.

Adult↗
PubMed1992

Violent visual hallucinations and aggression in frontal lobe dysfunction: clinical manifestations of deep orbitofrontal foci.

Three patients from different racial, social, and economic backgrounds were studied because of sudden intrusive thoughts: visions or intrusions of threatening scenes--violent, aggressive, and sometimes horrifying--that lasted from seconds to minutes. Apart from the association with intense anxiety, fear, and aggression, there was no association with oculomotor, motor, sensory, or autonomic dysfunction or altered conscious state. Patients had abnormal intermittent discharges that arose from frontal areas and probably did not spread further. Carbamazepine was useful in two cases. The authors suggest that violent, brief hallucinations with no other epileptic sign may be manifestations of frontal lobe seizures.

Adult↗
PubMed1992

Assessment of regional cerebral perfusion by 99Tcm-HMPAO SPECT in chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a severely disabling illness of uncertain aetiology. It is characterized by a chronic, sustained or fluctuating sense of debilitating fatigue without any other known underlying medical conditions. It is also associated with both somatic and neuropsychological symptoms. Both physical and laboratory findings are usually unremarkable. Regional cerebral blood flow (rCBF) was assessed in 60 clinically defined CFS patients and 14 normal control (NC) subjects using 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO) single photon emission computed tomography (SPECT). Compared with the NC group, the CFS group showed significantly lower cortical/cerebellar rCBF ratios, throughout multiple brain regions (P < 0.05). Forty-eight CFS subjects (80%) showed at least one or more rCBF ratios significantly less than normal values. The major cerebral regions involved were frontal (38 cases, 63%), temporal (21 cases, 35%), parietal (32 cases, 53%) and occipital lobes (23 cases, 38%). The rCBF ratios of basal ganglia (24 cases, 40%) were also reduced. 99Tcm-HMPAO brain SPECT provided objective evidence for functional impairment of the brain in the majority of the CFS subjects. The findings may not be diagnostic of CFS but 99Tcm-HMPAO SPECT may play an important role in clarifying the pathoaetiology of CFS. Further studies are warranted.

Adolescent↗
PubMed1992

Technetium-99m-HMPAO SPECT in the evaluation of patients with a remote history of traumatic brain injury: a comparison with x-ray computed tomography.

The functional imaging modality has potential for demonstrating parenchymal abnormalities not detectable by traditional morphological imaging. Fifty-three patients with a remote history of traumatic brain injury (TBI) were studied with SPECT using 99mTc-hexamethylpropyleneamineoxime (HMPAO) and x-ray computed tomography (CT). Overall, 42 patients (80%) showed regional cerebral blood flow (rCBF) deficits by HMPAO SPECT, whereas 29 patients (55%) showed morphological abnormalities by CT. Out of 20 patients with minor head injury, 12 patients (60%) showed rCBF deficits and 5 patients (25%) showed CT abnormalities. Of 33 patients with major head injury, 30 patients (90%) showed rCBF deficits and 24 patients (72%) showed CT abnormalities. Thus, HMPAO SPECT was more sensitive than CT in detecting abnormalities in patients with a history of TBI, particularly in the minor head injury group. In the major head injury group, three patients showed localized cortical atrophy by CT and normal rCBF by HMPAO SPECT. In the evaluation of TBI patients, HMPAO SPECT is a useful technique to demonstrate regional brain dysfunction in the presence of morphological integrity as assessed by CT.

Adult↗
PubMed1991

The scintigraphic evaluation of Huntington's disease and other movement disorders using single photon emission computed tomography perfusion brain scans.

The increasing availability of single-photon emission computed tomography (SPECT) perfusion brain scans has led to the investigation of a variety of neuropsychiatric conditions including the movement disorders such as Huntington's and Parkinson's disease. In general, observers have noted that Huntington patients have bilaterally decreased uptake of technetium 99m HM-PAO and iodine 123 IMP in the basal ganglia regions involving the heads of the caudate nucleic and adjacent structure, which reflects decreased neuronal function. These functional changes precede the morphological changes due to caudate nucleus atrophy that are observed on computed tomography and magnetic resonance imaging. Cortical changes occur in severely diseased Huntington's patients but are more nonspecific. Prediction of individuals at risk for Huntington's disease using SPECT scans should be done with caution and in association with other clinical data. In contrast, in Parkinson's disease mild diffusely decreased perfusion is commonly noted throughout the cerebral structures, except for the cerebellum. In Parkinson's disease, there is less agreement among observers as to whether the basal ganglia are abnormal. Some observers report that there are no specific basal ganglia perfusion defects in excess of those changes seen elsewhere in the brain. Others report diminished basal ganglia uptake associated with L-dopa therapy in some Parkinson's patients, and in patients with hemi-parkinsonism there have been perfusion deficits reported in the contralateral basal ganglia. In some Parkinson patients, bilateral Alzheimer's-like posterior temporoparietal cortical perfusion defects have been observed in association with progressive dementia. Basal ganglia and cortical perfusion changes also have been reported in a few patients with a variety of other less common movement disorders.

Brain↗
PubMed1991

Rabbit syndrome, antidepressant use, and cerebral perfusion SPECT scan findings.

The rabbit syndrome is an extrapyramidal side effect associated with chronic neuroleptic therapy. Its occurrence in a patient being treated with imipramine is described, representing the first reported case of this syndrome in conjunction with antidepressants. Repeated cerebral perfusion SPECT scans revealed decreased basal ganglia perfusion while the movement disorder was present, and a return to normal perfusion when the rabbit syndrome resolved.

Basal Ganglia Diseases↗
PubMed1990

The cluster diathesis.

We present further evidence for a sympathetic defect of vasomotor control of the anterior cerebral artery (ACA) on the side of the headache during cluster periods. In 119 cluster headache patients, utilizing transcranial Doppler, we measured CO2 reactivity of the major intracranial vessels, in and out of cluster. Reactivity was significantly lower during the cluster period, but only in the ACA on the side of the headache. Nineteen patients followed sequentially for a full cycle (ie/both in and out of a cluster period) showed the same changes. In 3 out of 6 patients in an active cluster period, we describe a lesion on Gallium single-photon emission computerized tomography (SPECT) in the region of the cavernous sinus which fades as the patient moves out of cluster. It is felt that this lesion may represent the cavernous sinus plexus lesion postulated as the central lesion in cluster. Changes in the sympathetic outflow at this point could explain the changes we have described in ACA CO2 reactivity during cluster.

Adult↗
PubMed1988

Increased iofetamine I 123 brain uptake in metastatic melanoma.

Four of five patients with brain metastases from melanoma had increased lofetamine I 123 uptake in the region of the tumor deposits. A comparison group of five patients with melanoma with no clinical or radiologic evidence of brain involvement and 46 of 47 patients without malignant melanoma but with known brain tumors of other histologic types had normal or decreased iofetamine I 123 brain uptake in the region of the tumor. An exception was one patient whose metastatic small cell lung cancer to the brain showed focally increased uptake. These findings suggest that certain brain tumors such as melanoma are capable of selectively binding iofetamine I 123 because of specific chemical properties of the radiopharmaceutical. Increased uptake of iofetamine I 123 in brain lesions in a patient at risk for metastatic melanoma may be a useful aid to differential diagnosis.

Amphetamines↗
PubMed1988

Decreased iodine-123 IMP caudate nucleus uptake in patients with Huntington's disease.

To determine whether I-123 isopropyl iodoamphetamine (IMP) uptake is reduced in the basal ganglia of patients with Huntington's disease compared with that in aged-matched normal and abnormal control subjects, a caudate ratio was defined that compared the average separation (in pixel units) between the midline and the left and right caudate heads to the width of the brain as measured on transaxial cross-sections of I-123 IMP SPECT brain images. For six patients with Huntington's disease, the average caudate ratio was 29.0% (SD +/- 2.7%), significantly higher than that for 12 normal volunteer subjects (average caudate ratio, 19.1% +/- 3.5%; p less than 0.001) and 13 patients with a variety of other neurologic disorders (average caudate ratio, 19.3 +/- 2.2%; p less than 0.001).

Amphetamines↗