Biomedical subjects

S Higano

Publications and source records attributed to S Higano.

At least 37 records · Page 2Linked to original sources

PubMed1998

Comparison of ipsilateral activation between right and left handers: a functional MR imaging study.

We used fMRI to compare the ipsilateral activation in the sensorimotor region (SMR) during dominant and non-dominant hand motor tasks between right and left handers. In right handers, the ipsilateral activation was significantly greater during non-dominant (left) hand task than dominant (right) hand task, while in left handers, it showed no significant difference. The ipsilateral activation was most pronounced in the precentral subregion (presumably corresponding to the premotor area) during either hand task in both groups. We conclude that the different patterns of ipsilateral activation might be mainly explained by the hemispheric dominance. The skill of the hand and complexity of tasks may be related to the predominant activation of the premotor area.

Adult↗

PubMed1998

Hemorrhage in pituitary adenoma: correlation of MR imaging with operative findings.

The aim of this study was to correlate MR imaging and operative findings of hemorrhage in pituitary macroadenomas. We retrospectively reviewed MR images of 113 surgically proven pituitary adenomas. All patients were examined on a 1.5-T MR system. The intensity of intratumoral cystic cavities was correlated with operative findings. In 15 patients with pituitary apoplexy, we determined relationship between interval of MR examination after apoplectic event and MR signal intensity. In 8 patients with repeated preoperative MR examination, we evaluated sequential changes of intratumoral hemorrhage. There were 54 cavities at surgery: 52 were hemorrhagic and 2 were nonhemorrhagic. Twenty-nine of 52 hemorrhagic cysts demonstrated high/low signal (H/L) fluid-fluid levels on T2-weighted image (T2WI). In 19 of them, two components could be separately seen at operation: the supernatant high-intensity area represented xanthochromic fluid, and the dependent low-intensity area represented liquefied hematoma. The H/L fluid-fluid level was observed predominantly in hematomas on MR images obtained after longer intervals. In patients with repeated MR examination, follow-up MR imaging revealed additional hemorrhage or new formation of fluid-fluid levels. It was surprising that 12 of 14 cysts preoperatively judged as nonhemorrhagic in fact contained hemorrhagic components. The preoperative MR images are well correlated to the operative findings in hemorrhagic pituitary macroadenomas. It proved that 52 of 54 cystic cavities had hemorrhagic component.

Adenoma↗

PubMed1998

Functional MR imaging of cortical activation of the cerebral hemispheres during motor tasks.

PURPOSE: We used functional MR imaging to evaluate cortical activation in the precentral, central, and postcentral regions of the contralateral and ipsilateral cerebral hemispheres during left- and right-handed motor tasks. METHODS: Ten healthy right-handed volunteers were studied with echo-planner MR imaging (1.5 T) while performing alternating finger apposition tasks with both hands. During the hand tasks, the areas of activated pixels were compared between subregions (precentral, central, and postcentral) of the contralateral and ipsilateral sensorimotor cortex. RESULTS: The activated area of the contralateral sensorimotor cortex was significantly larger than that of the ipsilateral cortex during tasks with either hand, whereas the ipsilateral activated area was significantly larger during the left-handed task than during the right-handed task. Ipsilateral activation was greatest in the precentral region, less in the central region, and least prominent in the postcentral region. CONCLUSIONS: Our results confirmed those of previous investigators that ipsilateral activation is more pronounced during left-sided movements than during right-sided movements. The variation in activation of the precentral, central, and postcentral subregions suggests different roles of the ipsilateral and contralateral hemispheres during motor tasks.

Adult↗

PubMed1998

[New methods for measuring atlanto-axial vertical subluxation in rheumatoid arthritis by MR imaging].

We proposed two new methods of measuring atlanto-axial vertical dislocation in rheumatoid arthritis by MR imaging. One is the distance from the subdental synchondrosis of the axis to the diameter of the ring of the atlas. The other is the distance from the midpoint of the anteroposterior ends of the inferior margin of the axis to the diameter of the ring of the atlas. Values were also determined by the Ranawat method and the Redlund-Johnell method. There was good correlation between values determined by the new methods and those determined by the Ranawat method and Redlund-Johnell method.

Adolescent↗

PubMed1997

Correlation of lesions in the hippocampal region noted on MR images with clinical features.

The purpose of our work was to compare the MR imaging findings of obvious hippocampal and/or juxtahippocampal lesions with corresponding clinical features. Magnetic resonance images of 63 patients with obvious lesions in the hippocampal and/or juxtahippocampal regions were reviewed and their findings were correlated with patients' clinical characteristics. Based on the MR and clinical findings, the patients were divided into four groups: (a) 26 patients with space occupying lesions or suspected vascular malformation frequently causing symptomatic temporal epilepsy; (b) 14 with hippocampal infarcts, which when left-sided or bilateral caused amnesia; (c) 11 with encephalitis and 5 with old temporal contusion usually accompanied by both amnesia and epilepsy; and (d) 7 with temporal atrophy and progressive dementia of subacute onset. Magnetic resonance imaging allows precise localization and evaluation of the clinical correlates of hippocampal and juxtahippocampal lesions, which frequently caused symptomatic temporal epilepsy and/or amnesic syndrome.

Adolescent↗

PubMed1997

CT and MR imaging of craniopharyngioma.

We reviewed imaging findings of CT and MR imaging in 20 cases of surgically confirmed craniopharyngioma in an attempt to determine their relation to patterns of tumor extent. The relationship between these patterns and the frequency of preoperative CT diagnosis and MR imaging diagnosis according to the surgical diagnosis were determined. The CT technique was superior to MR imaging in the detection of calcification. The MR imaging technique was superior to CT for determining tumor extent and provided valuable information about the relationships of the tumor to surrounding structures. Thus, CT and MR imaging have complementary roles in the diagnosis of craniopharyngiomas. In cases of possible craniopharyngioma, noncontrast sagittal T1-weighted images may enable the identification of the normal pituitary, possibly leading to the correct diagnosis.

Adolescent↗

PubMed1997

Supratentorial primary intra-axial tumors in children. MR and CT evaluation.

PURPOSE: To evaluate the MR and CT features of pediatric supratentorial intra-axial tumors with respect to differential diagnosis and the role of each investigation modality. MATERIAL AND METHODS: MR and CT findings in 40 children with 12 types of pathologically proven histological tumors were reviewed. RESULTS: The location of tumors might be one clue to differential diagnosis. In our material, cysts (60%), calcifications (45%), and intratumoral hemorrhages (27%) were found in the tumors. Characteristic features noted in some lesions included: peritumoral hemosiderin deposition in cavernous angiomas; intratumoral flow void in a choroid plexus carcinoma and in glioblastomas; and hemicerebral atrophy in germinomas. A comparison between malignant and benign tumors showed perifocal edema and a mass effect to be significantly more common in malignant lesions. Homogeneous enhancement suggested a benign tumor and an inhomogeneous pattern represented malignancy, while the lack of obvious enhancement did not always suggest benignity. Intratumoral calcium deposition was a not uncommon finding in malignant tumors. CONCLUSION: In most cases, the exact diagnosis should be made by histological examination but it is important for treatment planning that the appropriate depiction of tumor extension and tissue characterization be made by MR and CT.

Adolescent↗

PubMed1997

[Neurophysiological monitoring during surgery for astrocytoma at the motor strip with awake craniotomy].

We present a case of a 26-year-old male with fibrillary astrocytoma at the right face motor cortex. Surgery was performed with the patient under propofol anesthesia. Stimulation mapping techniques for localization of the motor and sensory cortex were applied. The entire right face motor cortex was resected up to the hand region, resulting in a gross total removal of the tumor. Postoperatively, the patient only had transient weakness of the left lower face. For improving the prognosis of gliomas around the motor strip, it is necessary to resect the tumor as much as possible while preserving motor function. Preoperative understanding of the anatomical relationship between the tumor and the motor strip, and intraoprative neurophysiological monitoring may be necessary. In order to simulate the operative fieled preoperatively, we superimposed the superficial venous image obtained by magnetic resonance angiography (MRA) upon the surface anatomy scan (SAS). Magnetoencephalography (MEG) provided precise localization of the central sulcus, preoperatively. The methods of direct cortical stimulation to localize sensorimotor pathways with awake craniotomy enabled us to resect the tumor maximally and to minimize morbidity.

Adult↗

PubMed1996

Congenital absence and aberrant course of the internal carotid artery.

We retrospectively reviewed the imaging features of an aberrant course of the internal carotid artery (ICA) in one patient and its unilateral absence in four. Absence of the ICA was initially detected by MRI and MR angiography in both patients who underwent these examinations. CT revealed an abnormal or absent carotid canal in all cases. Radiological diagnosis by MRI and MR angiography could play an important role in the diagnosis.

Adult↗

PubMed1996

Reye's syndrome with cortical laminar necrosis: MRI.

Serial MRI findings are described in two patients with Reye's syndrome, demonstrating diffuse cortical and white matter changes. In the acute stage, T2-weighted images showed subtle but definite laminar high signal and contrast-enhanced T1-weighted images laminar enhancement, along the entire cerebral cortex bilaterally. In the chronic stage, unenhanced T1-weighted images showed diffuse cortical laminar high signal. These characteristic MRI features seemed very similar to those of laminar cortical necrosis in hypoxic brain damage. MRI also displayed delayed white matter changes with cerebral atrophy.

Atrophy↗

PubMed1996

Cerebral oxygen and glucose metabolism and blood flow in mitochondrial encephalomyopathy: a PET study.

Cerebral blood flow (CBF), oxygen metabolism (CMRO2), and glucose metabolism (CMRGlc) were measured using positron emission tomography in five patients diagnosed as having mitochondrial encephalomyopathy. The molar ratio between the oxygen and glucose consumptions was reduced diffusely, as CMRO2 was markedly decreased and CMRGlc was slightly reduced. The CBF showed less changes. The CBF increase on hypercapnia was smaller than normal, though this was not significant. CBF with hypocapnia demonstrated a significant reduction compared with the normal. These results suggest that oxidative metabolism is impaired and anaerobic glycolysis relatively stimulated, due to a primary defect of mitochondrial function, and that mild lactic acidosis occurs in brain tissue because of impaired utilisation of pyruvate in the TCA cycle. As these findings appear to indicate directly a characteristic of this disease, such measurements may be a useful tool for assessment of the pathophysiology and for diagnosis of mitochondrial encephalomyopathy.

Acidosis, Lactic↗

PubMed1996

[CT and MR imaging findings in a case of cerebral alveolar echinococcosis masquerading as brain tumor].

We report a rare case of cerebral alveolar echinococcosis that was verified by pathological examination. The lesion presented as an intracranial mass which was slightly hyperdense on CT scans and very hypointense with central hyperintensity on T2-weighted MR images. The lesion exhibited marked contrast enhancement on both CT and MR images and was accompanied by extensive white matter edema. Although radiological differentiation from brain tumor was difficult, hypointensity on T2-weighted MR images appeared to be characteristic of lesions of cerebral alveolar echinococcosis.

Brain↗

PubMed1996

[Leigh syndrome: serial CT and MR imaging findings].

Serial CT and MRI findings in five patients (two boys and three girls) with Leigh syndrome were retrospectively reviewed in a follow-up period lasting from six months to 10 years. The two boys were found to have cytochrome c oxidase deficiency and one of the girls to have mitochondrial DNA mutation, while the remaining two girls had no detectable enzyme deficiency. CT and MRI revealed symmetrical involvement of the brain bilaterally in all cases. The focal lesions were found most frequently in putamina and caudate nuclei (four cases each), followed by thalami (three cases), globi pallidi, and midbrain (two cases each). In addition, diffuse white matter and/or cortical lesions were disclosed in three cases. MRI and CT at an early stage of the disease revealed swollen, symmetrical lesions which showed shrinkage in size accompanied by the adjacent brain atrophy on later images. Some lesions were detected only in the early stage and were not shown in later images. Thus, careful reading of sequential changes appears to be required for accurate diagnosis of Leigh syndrome.

Brain↗

PubMed1996

[MR imaging of carbon monoxide intoxication: evaluation of 13 cases to discuss the relation between MR findings and clinical course].

MR images of the brain were retrospectively reviewed in 13 patients with carbon monoxide (CO) poisoning to examine the relation between the MR findings and clinical course. The patients included 11 men and 2 women whose ages ranged from 6 to 88 years (mean, 38 years). Repeated MR studies of at most five times were performed on 9 patients. Lesions in the bilateral globus pallidi were found in 5 cases showing hyperintensity on T2-weighted images (T2WI) and iso-to hypointensity on T1-weighted images (T1WI). The patients with only pallidi lesions clinically recovered well. Hyperintense white matter lesions were recognized on T2WI in 8 patients, including all 5 with delayed encephalopathy. Sequential studies generally showed a tendency of regression of these hyperintense lesions with improvement of symptoms, indicative of reversible demyelination as documented in the pathological literature. One patient with poor prognosis revealed white matter lesions, that were hyperintense on T2WI and very hypointense on T1WI, which may represent irreversible change. Thus, clinical course seems to be closely related with white matter lesions, but not with pallidi lesions. In cases of CO intoxication, therefore, MR study provides valuable information on patients' clinical prognoses.

Adolescent↗

PubMed1995

Leukoencephalopathy in childhood hematopoietic neoplasm caused by moderate-dose methotrexate and prophylactic cranial radiotherapy--an MR analysis.

PURPOSE: The main purpose of this study was to determine influential factors related to minor leukoencephalopathy (LEP) caused by moderate-dose methotrexate (MTX) and prophylactic cranial radiotherapy (CRT) in childhood hematopoietic malignancies. We also compared the incidence of LEP following this treatment to that reported in the literature following treatment with high-dose MTX alone. METHODS AND MATERIALS: Thirty-eight pediatric patients of hematopoietic malignancies (37 acute lymphoblastic leukemias, 1 non-Hodgkin lymphoma) who were given CRT (18-24 Gy) as well as prophylactic intrathecal and per os MTX were studied for leukoencephalopathy by magnetic resonance (MR) imaging. All the patients were free from grave neuropsychiatric disturbances. The data were examined to elucidate the influential ones of five factors (patients' age, doses of intrathecal and per os MTX, dose of CRT, interval between treatment, and MR study) to develop LEP using multiple regression analysis. To compare the effect of moderate-dose MTX and prophylactic CRT on LEP to that of high-dose MTX alone, we conducted literature review. RESULTS: Seven out of 38 patients (18%) developed LEP. From multiple regression analysis and partial correlation coefficients, the age and CRT dose seemed influential in the subsequent development of LEP. The incidence of LEP following treatment with moderate-dose MTX and prophylactic CRT appears to be less than that reported in the literature following treatment with intravenous high-dose MTX. However, even moderate-dose MTX in combination with CRT can result in a significant incidence of MR-detectable LEP, particularly in children 6 years of age or younger receiving 24 Gy. CONCLUSION: Leukoencephalopathy was caused by moderate-dose MTX and prophylactic CRT in pediatric patients, probably less frequently than by high-dose MTX treatment alone. The influential factors were patient's age and CRT dose.

Adolescent↗

PubMed1994

[MR imaging findings of nonketotic hyperglycinemia. 2 cases of neonatal onset].

We presented MR (magnetic resonance) images findings of the brain in nonketotic hyperglycinemia (NKH) from 2 patients of neonatal onset. MR findings in our cases of NKH are compatible with the pathological alterations described in the literature; MR images revealed delayed myelination of the cerebral white matter and hypoplasia of the corps callosum. The latter finding particularly seemed to be relatively characteristic to NKH. MR examination is the imaging modality of choice for this disease because it can demonstrate the degree of myelination, and development of the corpus callosum particularly on sagittal section.

Brain↗

PubMed1994

[CT and MR imaging findings of sphenoidal masses].

CT and MR imaging findings of 57 sphenoidal masses were retrospectively reviewed to assess the possibility of differential diagnosis between them. Various kinds of masses such as pituitary adenoma, epipharyngeal cancer, mucocele, chordoma, chondroma, chondrosarcoma, distant metastasis, multiple myeloma, fibrous dysplasia, craniopharyngioma, hemangiopericytoma, giant cell tumor, primary sphenoidal cancer, malignant melanoma, leukemia, histiocytosis X, and giant cell tumor were included in this series. CT scanning was performed in all cases, while MR images were obtained in 48 cases using a spin-echo pulse sequence. The relative density of the masses, bony changes and calcification were evaluated on CT, and on MR images, signal intensity of the masses relative to the normal gray matter, contrast enhancement and extension/contour were evaluated. Although no single feature appeared to be specific to the masses, detection of calcification on CT, identification of the normal pituitary gland as deformed or displaced on T1-weighted images, signal intensity on T2-weighted images, and extension of the masses seemed to be useful and should be examined in terms of their ability to assist in differential diagnosis. Finally, accommodative classification of sphenoidal masses primarily based on presumed origin or mode of extension was attempted.

Adolescent↗

PubMed1994

A method to quantitate cerebral blood flow using a rotating gamma camera and iodine-123 iodoamphetamine with one blood sampling.

A method has been developed to quantitate regional cerebral blood blow (rCBF) using iodine-123-labelled N-isopropyl-p-iodoamphetamine (IMP). This technique requires only two single-photon emission tomography (SPET) scans and one blood sample. Based on a two-compartment model, radioactivity concentrations in the brain for each scan time (early: t(e); delayed: td are described as: [formula: see text] respectively, where x denotes the convolution integral; Ca(t), the arterial input function; f, rCBF; and Vd, the regional distribution volume of IMP. Calculation of the ratio of the above two equations and a "table look-up" procedure yield a unique pair of rCBF and Vd for each region of interest (ROI). A standard input function has been generated by combining the input functions from 12 independent studies prior to this work to avoid frequent arterial blood sampling, and one blood sample is taken at 10 min following IMP administration for calibration of the standard arterial input function. This calibration time was determined such that the integration of the first 40 min of the calibrated, combined input function agreed best with those from 12 individual input functions (the difference was 5.3% on average). This method was applied to eight subjects (two normals and six patients with cerebral infarction), and yielded rCBF values which agreed well with those obtained by a positron emission tomography H2(15)O autoradiography method. This method was also found to provide rCBF values that were consistent with those obtained by the non-linear least squares fitting technique and those obtained by conventional microsphere model analysis. The optimum SPET scan times were found to be 40 and 180 min for the early and delayed scans, respectively. These scan times allow the use of a conventional rotating gamma camera for clinical purposes. Vd values ranged between 10 and 40 ml/g depending on the pathological condition, thereby suggesting the importance of measuring Vd for each ROI. In conclusion, optimization of the blood sampling time and the scanning time enabled quantitative measurement of rCBF with two SPET scans and one blood sample.

Aged↗