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Toshihide Ogawa

Publications and source records attributed to Toshihide Ogawa.

At least 19 recordsLinked to original sources
PubMed2006

[Evaluation of three-dimensional fast spoiled gradient recalled acquisition in the steady state (FSPGR) using ultra magnetic field 3-Tesla MRI for optimal pulse sequences of T1-weighted imaging].

The advantage of the higher signal-to-noise ratio (SNR) of 3-Tesla magnetic resonance imaging (3TMRI) contributes to the improvement of spatial and temporal resolution. However, T1-weighted images of the brain obtained by the spin-echo (SE) method at 3T MR are not satisfactory for clinical use because of radiofrequency (RF) field inhomogeneity and prolongation of the longitudinal relaxation time (T1) of most tissues. We evaluated optimal pulse sequences to obtain adequate T1 contrast, high gray matter/white matter contrast, and suitable postcontrast T1-weighted images using the three-dimentional (3D) fast spoiled gradient recalled acquisition in the steady state (FSPGR) method instead of the SE method. For the optimization of T1 contrast, the Ernst angle of the optimal flip angle (FA) was obtained from the T1 value of cerebral white matter with the shortest TR and TE. Then the most appropriate FA, showing the maximum contrast-to-noise ratio (CNR) and SNR, was obtained by changing the FA every 5 degrees at about the level of the Ernst angle. Image uniformity was evaluated by a phantom showing similar T1 and T2 values of cerebral white matter. In order to evaluate the effect of the contrast enhancement, signal intensity was compared by the same method using a phantom filled with various dilutions of contrast media. Moreover, clinical studies using full (0.1 mmol/kg) and half (0.05 mmol/kg) doses of Gd-DTPA were carried out with the most appropriate parameters of the 3D-FSPGR method. These studies indicated that the optimal pulse sequences for obtaining an adequate T1-weighted image of the brain using 3D-FSPGR are 9/2 msec (TR/TE) and 13 degrees (FA).

Adult↗
PubMed2006

CT-guided transthoracic needle biopsy using a puncture site-down positioning technique.

OBJECTIVE: We have developed a new CT-guided technique using puncture site-down positioning during the biopsy. The goal of our study was to determine the efficacy and safety of this technique for biopsy of lung lesions compared with the standard technique. MATERIALS AND METHODS: Medical records of 236 patients who underwent CT-guided transthoracic needle biopsy were retrospectively evaluated. This study included 89 cases that were biopsied using the standard technique (group A) and 147 cases that were biopsied using the puncture site-down positioning technique (group B). A 20-gauge automated cutting needle without coaxial technique was used in all patients. Medical records were reviewed for lesion size and location, biopsy results, and complications. RESULTS: When using the standard technique, the sensitivity for malignant lesions was 96.1%; the sensitivity for benign lesions, 92.1%; and diagnostic accuracy, 94.4%. Thirty-seven patients (41.6%) had pneumothorax, with 16 (18.0%) requiring chest tube placement. When using the puncture site-down positioning technique, the sensitivity for malignant lesions was 95.4%; the sensitivity for benign lesions, 93.3%; and diagnostic accuracy, 94.6%. Nineteen patients (12.9%) had pneumothorax, with four (2.7%) requiring chest tube placement. Other complications were minimal. CONCLUSION: CT-guided transthoracic needle biopsy using the puncture site-down positioning technique is an effective and safe procedure with a high diagnostic accuracy and low complication rate. This new technique is especially useful in reducing the rate of pneumothorax.

Adult↗
PubMed2006

White matter changes in elderly people: MR-pathologic correlations.

Magnetic resonance (MR) imaging features of white matter lesions, often seen in the elderly, are correlated with histologic findings. Dilatation of perivascular spaces is seen, especially in the frontal and/or parietal subcortical white matter; the spaces are less than 3 mm in diameter and have sharp margins with no perifocal abnormality. Old lacunar infarcts are larger than 3 mm in diameter and are irregularly shaped and accompanied by perifocal myelin pallor and gliosis. Periventricular hyperintensity, including cap and rim, histologically shows myelin pallor, dilatation of perivascular spaces, discontinuity of the ependymal lining, and subependymal gliosis. Deep and subcortical white matter hyperintensity reflects myelin pallor and dilatation of perivascular spaces. Diffuse white matter lesion, seen in Binswanger's disease, shows myelin pallor and tissue rarefaction associated with loss of myelin and axons. U-fibers are usually well preserved. Severe arteriosclerosis and arteriolosclerosis are usually seen in the white matter. Knowledge of the pathologic features of incidental changes in white matter helps in understanding MR imaging findings.

Aged↗
PubMed2005

Curvilinear T1 hyperintense lesions representing cortical necrosis after cerebral infarction.

Curvilinear T1 hyperintense lesions in the cerebral cortex in patients with subacute infarction were investigated for: (1) the presence or absence of T2* hypointensity and (2) correlations with neuropathologic findings. Thirty-six consecutive patients with subacute to chronic embolic infarction, in whom curvilinear hyperintense lesions in the infarcted cortex were seen on T1-weighted images, underwent echo-planar gradient-echo (GRE-EPI) T2*-weighted imaging. GRE-EPI T2*-weighted imaging revealed no evidence of hemorrhage within the curvilinear T1 hyperintense lesions of the cerebral cortex in all of the patients. In 11 of the 36 patients, focal hypointense lesions were seen in the depth of infarcted gyri on GRE-EPI T2*-weighted images. In the remaining 25 patients, no T2* hypointensities were seen in the infarct zone. Pathological correlation was performed in a patient with middle cerebral artery infarction and curvilinear hyperintense lesions on postmortem T1-weighted images. In the autopsied brain, curvilinear T1 hyperintense lesions corresponded to necrosis of all the cortical layers on histological examination. These data suggest that curvilinear hyperintense lesions in the cerebral cortex on T1-weighted images during the subacute to chronic period of cerebral infarction may not represent hemorrhage.

Aged↗
PubMed2005

Clinically silent choroid plexus cyst: evaluation by diffusion-weighted MRI.

We retrospectively reviewed diffusion-weighted magnetic resonance images of 57 patients with a choroid plexus cyst diagnosed by contrast-enhanced T1-weighted imaging. All the cysts appeared to represent incidental findings. Thirty-eight of 57 patients had bilateral cysts and 19 had unilateral ones. On diffusion-weighted images, 78 of 95 cysts showed homogeneously high signal intensity, 12 showed focal high signal areas, and 5 had no portion with a high signal. The apparent diffusion coefficient of the high signal areas in the cysts was (1.46+/-0.14) x10(-3) mm(2)/s, intermediate between the apparent diffusion coefficients of cerebrospinal fluid and cerebral white matter, (3.15+/-0.67) x10(-3) and (0.79+/-0.22) x10(-3) mm(2)/s, respectively. Pathological correlation was available in one case, showing high signal intensity areas in the glomera of the choroid plexuses in the lateral ventricles on diffusion-weighted images corresponding to gelatinous cysts with highly proteinaceous content.

Adult↗
PubMed2005

Clinical usefulness of In-111 chloride and Tc-99m Sn colloid scintigraphy in the diagnosis of intrathoracic extramedullary hematopoiesis.

We report a case of intrathoracic extramedullary hematopoiesis associated with hemolytic anemia. While the paravertebral localization of the lesions demonstrated on CT and MRI was suspicious of intrathoracic extramedullary hematopoiesis, In-111 chloride and Tc-99m Sn colloid bone marrow scintigraphies showing a bone marrow element of the lesion were useful to confirm the diagnosis.

Anemia, Hemolytic↗
PubMed2005

Localization of chyle leakage site in postoperative chylothorax by oral administration of I-123 BMIPP.

The authors present a 71-year-old woman who had a right chylothorax after right upper lobectomy for lung cancer. As the chylothorax was considered to be due to thoracic duct injury at the time of operation, lymphoscintigraphy was performed by oral administration of I-123 beta-methyl-iodophenyl pentadecanoic acid (BMIPP). After visualization of the stomach and intestine, abnormal accumulation of the radiotracer was found initially around the right pulmonary hilum and then spread laterally in the upper pleural cavity, indicating chyle leakage in the region of the right pulmonary hilum. Scintigraphic finding was well correlated with the subsequent thoracoscopic observation, showing chyle leakage from a lymphatic tributary near its confluence to the thoracic duct at the level of the azygos continuation. The disruption site was ligated by video-assisted-thoracoscopic-surgery procedure with successful termination of the chyle leakage. Lymphoscintigraphy by oral administration of I-123 BMIPP is thought to be a useful method for localization of chyle leakage in patients with chylothorax induced by thoracic surgery.

Administration, Oral↗
PubMed2005

Sequential MR imaging and SPECT studies in herpes simplex encephalitis with crossed cerebellar hyperperfusion.

We report a case of herpes simplex encephalitis in which sequential MR imaging and SPECT studies showed interesting findings. SPECT in the acute stage showed wide increased uptake in the left cerebral hemisphere, as well as increased uptake in the contralateral right cerebellar hemisphere. T1-weighted images in the subacute stage showed hyperintense signals along the cerebral cortices, but T2*-weighted gradient-echo images did not show any signal decrease caused by the magnetic susceptibility effect of hemoglobin degradation. Sequential SPECT studies in addition to MR imaging facilitate precise understanding of the pathophysiology of herpes simplex encephalitis.

Aged↗
PubMed2005

Cerebral cortical and white matter lesions in chronic hepatic encephalopathy: MR-pathologic correlations.

We correlated MR images with histologic findings in two autopsy-proven cases of chronic hepatic encephalopathy. Cortical hyperintensities on T2-weighted images histologically revealed pseudolaminar spongy degeneration in the deep layers of the cerebral cortices and hyperintensities in the cerebral white matters showed tissue rarefaction associated with loss of myelin and axons but without reactive astrocytosis. Both lesions were considered to be caused by chronic hepatic encephalopathy.

Aged↗
PubMed2005

Remote effect of optic tract trauma in the occipital lobe (case report).

Traumatic brain damage can result in severe visual impairments including hemianopia. Lesions correlated with hemianopia can be located in any part of the retrochiasmatic optic pathway. However, traumatic lesions of the optic tract are relatively rare. We present a case with posttraumatic left homonymous hemianopia who had signal intensity change at the ipsilateral optic tract on MR imaging and ipsilateral occipital hypoperfusion on SPECT imaging.

Adult↗
PubMed2005

Pallidoreticular damage in acute carbon monoxide poisoning: diffusion-weighted MR imaging findings.

We describe a case of carbon monoxide poisoning that led to pallidoreticular damage and delayed leukoencephalopathy. Serial diffusion-weighted MR imaging was performed. A restricted water diffusion pattern was demonstrated in the globus pallidus and substantia nigra in the early stage. Diffusion-weighted imaging is useful for early identification of the effects of acute carbon monoxide poisoning.

Adult↗
PubMed2005

[Cerebral atrophy and crossed cerebellar atrophy following acute subdural hematoma in infant].

Crossed cerebellar atrophy (CCA) on imaging study reflects secondary degeneration of the cerebellar hemisphere caused by neuronal disconnection with the contralateral cerebral hemisphere. We report an 11-month-old child with traumatic left acute subdural hematoma, who showed crossed cerebellar atrophy on MR images. Eighteen months after the trauma, MR images showed brain atrophy not only in the left cerebral hemisphere but also in the right cerebellar hemisphere. The cerebellar atrophy was prominent in the lateral part. This finding is consistent with CCA and may support neuronal interactions between the cerebral hemisphere and the lateral part of the contralateral cerebellar hemisphere.

Atrophy↗
PubMed2005

[A case of synovial sarcoma in the submandibular region].

Synovial sarcomas are a less common cervical tumor in young patients. We report a 23-year-old man with synovial sarcoma in the submandibular region. T2-weighted MR images demonstrated a mixed-intensity tumor attached to the submandibular gland. T1-weighted MR images revealed a focal area with mildly increased signal intensity, indicating intratumoral hemorrhage. MR images were also useful for visualization of tumor extension. Synovial sarcoma should be considered in the differential diagnosis of well-defined inhomogeneous tumors adjacent to the submandibular gland in young adults.

Adult↗
PubMed2005

[MR imaging for evaluation of severe facial nerve damage in patients with facial nerve palsy].

PURPOSE: To evaluate the usefulness of MR imaging for the detection of severe facial nerve damage in patients with facial nerve palsy. MATERIALS AND METHODS: We retrospectively reviewed 26 consecutive patients with facial nerve palsy (13 non-responders and 13 responders). T1-weighted, T2-weighted, and postcontrast T1-weighted images were obtained in all patients. FLAIR images were also obtained in 3 non-responders. RESULTS: The geniculate ganglion, labyrinthine segment, and tympanic segment or mastoid segment showed high signal intensity on T2-weighted images in 9 of 13 non-responders, whereas high signal intensity of the nerve was only seen in 1 of 13 responders. FLAIR imaging revealed high signal intensity lesions of the distal intrameatal segment in 2 non-responders. Contrast enhancement of the facial nerve showed a similar pattern in non-responders and responders. High signal intensity lesions on T2-weighted or FLAIR images showed enhancement on postcontrast T1-weighted images. CONCLUSION: These results suggest that a high signal intensity area on T2-weighted images is a marker of severe facial nerve damage. FLAIR imaging is useful for identification of T2-prolongation in the distal intrameatal segment.

Adolescent↗
PubMed2004

Multicystic acoustic schwannoma with intratumoral hemorrhage: a report of two cases.

We encountered two multicystic acoustic schwannomas with intratumoral hemorrhage. The radiological appearance in each case was similar to that obtained with CT and MRI. From a histological perspective, in each case we observed hypervascularity with thin-walled, dilated vessels in clusters and hemosiderin depositions around the dilated vessels.

Adult↗
PubMed2004

HTLV-I carrier with unusual brain MR imaging findings.

We describe unusual brain MR imaging findings in a patient who is an HTLV-I carrier without myelopathy. T2-weighted MR images showed hyperintense signal abnormalities in the pyramidal tract, superior and middle cerebellar peduncles, and decussation of the superior cerebellar peduncles, in addition to subcortical white matter involvement. Diffusion-weighted images also showed hyperintense signal abnormalities in the same regions by T2 shine-through effect.

Brain↗
PubMed2004

Role of KL-6 in evaluating the disease severity of rheumatoid lung disease: comparison with HRCT.

OBJECTIVE: To determine the role of KL-6 (Krebs von den Lungen-6) in evaluating the disease severity of pulmonary lesions in rheumatoid arthritis (RA) compared with high resolution computed tomography (HRCT) findings. METHODS: Fifty serum KL-6 levels and HRCT images were prospectively obtained from 47 RA patients. Eight HRCT findings were classified into five grades. Patients were also divided into two groups according to the KL-6 threshold level and HRCT findings were evaluated. RESULTS: There was a positive correlation between the serum KL-6 level and the total CT score (r = 0.83). Reticular opacity most closely related to the serum KL-6 levels (r = 0.84). In the high KL-6 group (n = 10), the average CTscore was markedly increased (64.6 points) and severe honeycombing expanded into the whole lung. One case revealed diffuse ground glass opacity. In 12 of 40 cases in the normal KL-6 group, CT scores mildly increased compared with the other cases (over 20 points). The predominant finding of these cases could be classified into four types: (1) narrow spread honeycombing; (2) subtle fibrosis; (3) airway diseases; and (4) dense consolidation. CONCLUSION: KL-6 is a useful marker to detect severe RA lung disease. It is also useful to distinguish non-fibrosis from fibrosis predominant cases. However, it sometimes could not detect early stage RA lung disease.

Adult↗