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Kazuhiro Tsuchiya

Publications and source records attributed to Kazuhiro Tsuchiya.

At least 19 recordsLinked to original sources
PubMed2006

Value of diffusion-weighted MR imaging in acute cervical cord injury as a predictor of outcome.

INTRODUCTION: We analyzed the findings of diffusion-weighted (DW) imaging using the single-shot fast spin-echo sequence in acute cervical cord injury and evaluated the usefulness of this method for predicting the prognosis. METHODS: Our patient group comprised 14 patients examined 2 h to 3 days after injury. First, we visually evaluated the DW imaging findings in all patients. Apparent diffusion coefficient (ADC) maps were also assessed in 13 patients. Second, we assessed follow-up magnetic resonance (MR) examinations obtained in six patients whose DW images showed hyperintensity. Third, we reviewed the functional outcome at discharge. RESULTS: The lesions showed hyperintensity in ten patients, and no abnormal signal was noted in the remaining four patients. The ADC maps showed restricted diffusion in all patients with hyperintensity on DW imaging except in one patient for whom the ADC map was unavailable. Repeated MR examinations obtained in six of the ten patients showed either myelomalacia or exacerbation. Seven of the ten patients (70%) required assistance and the other three were independent. Among the four patients without hyperintensity on DW imaging, three (75%) were independent and only one required assistance. CONCLUSION: DW imaging in acute cervical cord injury often reveals restricted diffusion. This finding may predict an unfavorable functional prognosis.

Adolescent↗
PubMed2006

Computerized detection of intracranial aneurysms for three-dimensional MR angiography: feature extraction of small protrusions based on a shape-based difference image technique.

We have improved a computerized scheme for the detection of intracranial aneurysms for three-dimensional (3-D) magnetic resonance angiography (MRA) by the use of image features of small protrusions extracted based on a shape-based difference image (SBDI) technique. Initial candidates were identified by use of a multiple gray-level thresholding technique in dot enhanced images, and by finding short branches in skeleton images. Image features related to aneurysms were determined based on candidate regions segmented by use of a region growing technique. For extracting additional features on small protrusions or small aneurysms, we have developed an SBDI technique, which was based on the shape-based difference between an original segmented vessel and a vessel with suppressed local change in thickness. The SBDI technique was useful for obtaining local changes in vessel thickness, i.e., SBD regions, which could be small aneurysms in the case of true positives, but thin or very small regions in the case of false positives. Many false positives were removed by means of rule-based schemes and linear discriminant analysis on various 3-D localized image features, including SBDI features. We tested the computerized scheme on 53 cases with 61 aneurysms and 62 nonaneurysm cases based on a leave-one-out-by-patient test method. As a result, false positives per patient decreased from 5.8 to 3.8, while a high sensitivity of 97% was maintained by use of the SBDI technique, in which SBDI features were effective for removing some false positives. The computer-aided diagnostic (CAD) scheme may be robust and useful in assisting radiologists in the detection of intracranial aneurysms for MRA.

False Positive Reactions↗
PubMed2006

Comparison of MRI sequences to detect ventriculitis.

OBJECTIVE: The ability of different MRI sequences to depict characteristic findings suggestive of ventriculitis was compared. CONCLUSION: The study comprised 20 brain MRI studies in 13 patients who had a final diagnosis of ventriculitis. Both diffusion-weighted imaging and FLAIR imaging were equally and highly sensitive for detecting intraventricular debris and pus--the most common MRI finding suggestive of ventriculitis. FLAIR imaging was superior to contrast-enhanced T1-weighted imaging for depicting ventricular wall abnormalities--a less common finding that also is suggestive of ventriculitis.

Adolescent↗
PubMed2005

Diffusion tractography of the cervical spinal cord by using parallel imaging.

We applied a single-shot echo-planar axial diffusion tensor sequence with parallel imaging for tractography of the cervical cord. Placing a large region of interest on a reconstructed sagittal image, the cervical cord was depicted as a tract bundle showing color-encoded cephalocaudally. By setting one region of interest in the cerebral peduncle and another in the entire cord on source images, tracts on each side were visualized. This method is promising for tractography of the cervical cord.

Adult↗
PubMed2005

Postoperative assessment of extracranial-intracranial bypass by time-resolved 3D contrast-enhanced MR angiography using parallel imaging.

PURPOSE: Our goals were to assess image quality of time-resolved contrast-enhanced MR angiography (CE MRA), by using 3D data acquisition along with a parallel imaging technique that can improve temporal resolution and to compare this technique with 3D-time-of-flight (TOF) MRA in the postoperative assessment of extracranial (EC)-intracranial (IC) bypass surgery. METHODS: On a 1.5T imaging system, we performed CE MRA by using a 3D fast field-echo sequence in combination with a parallel imaging technique, to obtain images in the coronal plane centered at the postoperative site. Our patient group comprised 17 patients, including 13 after superficial temporal artery-middle cerebral artery (MCA) anastomosis, 3 after external carotid artery-MCA anastomosis, and one after extracranial vertebral artery-posterior cerebral artery anastomosis. Visualization of the anastomosis and the distal flow on the CE-MRA images was assessed comparatively with that on 3D-TOF MR angiograms obtained at the same time. In 6 patients, we also compared the efficiency of visualization on CE-MRA images with that on conventional angiograms. RESULTS: A temporal resolution of 0.8 s/frame could be achieved with the technique employed. The bypass was better demonstrated postoperatively on CE-MRA images than on 3D-TOF MR angiograms in 13 patients (76%), whereas the 2 methods were equivalent in 4 patients (24%). Good correspondence of results was observed in the 6 patients for whom CE MRA and conventional digital subtraction angiography (DSA) images were compared. CONCLUSION: CE MRA by using the parallel imaging technique can increase image acquisition speed with sufficient image quality. This technique is at least equivalent to 3D-TOF MRA to evaluate the postoperative status of EC-IC bypass.

Adult↗
PubMed2004

Three-dimensional MR digital subtraction angiography using parallel imaging and keyhole data sampling in cerebrovascular diseases: initial experience.

We assessed the feasibility of MR digital subtraction angiography (DSA) using parallel imaging and keyhole data sampling in the diagnosis of cerebrovascular diseases (CVDs) in 11 patients. Their diseases included arterial trunk stenosis/occlusion ( n=4), aneurysm ( n=3), arteriovenous malformation ( n=2), venous angioma ( n=1), and sinus thrombosis ( n=1). The technique depicted not only anatomical features, comparably to MR angiography ( n=10/11), but also hemodynamics such as collateral flow at a temporal resolution of 1.68 s/frame. When compared with conventional angiograms ( n=7), details were missed in four patients (incomplete demonstration of aneurysmal neck in two and poor separation of AVM components in two). Although inferior to conventional angiography, this technique can provide both anatomical and hemodynamic information of CVDs.

Adolescent↗
PubMed2004

Diffusion-weighted MR imaging in acute spinal cord ischemia.

We report diffusion-weighted (DW) MR findings for acute spinal cord ischemia in a 56-year-old patient. MR imaging obtained approximately 3 h after symptom onset demonstrated an area of hyperintensity on DW images, but no conspicuous signal abnormality on T2-weighted images in the conus medullaris. DW imaging of the spinal cord can contribute to the early detection of spinal cord vascular compromise.

Acute Disease↗
PubMed2004

MR digital subtraction angiography with three-dimensional data acquisition in the diagnosis of brain tumors: preliminary experience.

MR digital subtraction angiography (DSA) visualizes intracranial vasculature using a rapid T1-weighted sequence and a bolus injection of gadolinium. Although two-dimensional sequences are most frequently used, we applied a three-dimensional technique in combination with a fast method of k-space filling to improve both the temporal and spatial resolutions. In this preliminary study, we assessed the feasibility of using this technique for the diagnosis of brain tumors in 21 patients by reviewing the obtained images and, in 10 patients, comparing the images with conventional angiograms. MR DSA visualized a tumor stain in 11 patients, a tumor mass effect in 9, and tumor-related vessels in 5. In 9 of the 10 patients for whom conventional angiograms were available, the two kinds of angiograms corresponded well. Three-dimensional MR DSA using our technique is a useful adjunct to conventional MR imaging for the visualization of tumor hemodynamics and, in some cases, tumor-related vessels and mass effects.

Adolescent↗
PubMed2004

[Imaging of Sturge-Weber syndrome: cranial CT and MR findings].

Sturge-Weber syndrome (SWS) is a phakomatosis characterized by vascular nevus flammeus, leptomeningeal venous angiomatosis, seizures, dementia, hemiplegia, hemianopsia, and glaucoma. Various imaging findings (gyriform calcification, atrophy of the ipsilateral hemisphere, leptomeningeal enhancement, ipsilateral choroid plexus enlargement, thickened calvarium, enlargement of paranasal sinuses and mastoid air cells, enlargement of deep veins, and white matter change adjacent to leptomeningeal enhancement) are seen in SWS. We examined the efficacy of CT and MR imaging in making the diagnosis in 14 patients. All patients underwent CT and MRI, and 11 of 14 patients underwent contrast-enhanced MRI. The most specific finding was leptomeningeal enhancement. Gyriform calcification, atrophy of the ipsilateral hemisphere, and ipsilateral chroid plexus enlargement were seen at high frequencies. Thickened calvarium was more frequent in adult patients. Enlargement of paranasal sinuses and mastoid air cells, enlargement of deep veins, and white matter change adjacent to leptomeningeal enhancement were seen in some (3-5) patients. A combination of findings of plain CT and MRI (including postcontrast MRI and MR venography) are useful for diagnosing SWS.

Adolescent↗
PubMed2004

[Neuroradiological study of progressive multifocal leukoencephalopathy associated with acquired immunodeficiency syndrome by MR imaging including diffusion-weighted imaging].

A 27-year-old man presented with subacute progressive left hemiparesis and hemi-sensory loss. Laboratory examinations revealed CD4 count at 14/microl, the HIV antibody positive, and HIV-RNA at 4.3 x 10(4) copies. Brain CT showed hypodence areas without contrast enhancement or mass effect in the right parietooccipital white matter and the right external capsule. On MR imaging, the lesion in the parietooccipital area showed hypointensity without enhancement on T1-weighted images and hyperintensity on T2-weighted images. On FLAIR images, the lesion showed hypointensity surrounded by hyperintensity. Meanwhile, diffusion-weighted images revealed three layers of different intensity. The area that demonstrated hypointensity on FLAIR images showed also hypointensity, while that in the area that demonstrated hyperintensity on FLAIR was divided into two parts; an area of isointense that encircles an hypointense area and a hyperintense area in the margin. The isointense and hypointense areas on diffusion-weighted images showed hyperintensity on apparent diffusion coefficient map. As JCV DNA was detected from his CSF, the diagnosis of PML was made. Based on comparative assessment of these MR images, it was speculated that the PML lesion appeared to be constituted of three parts from the margin to the center: cytotoxic edema, vasogenic edema, and liquefied lesion such as necrosis.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Evaluation of MR cisternography of the cerebellopontine angle using a balanced fast-field-echo sequence: preliminary findings.

We evaluated the feasibility of MR cisternography by the balanced fast-field-echo (bFFE) sequence, comparing with that by a turbo-spin-echo (TSE) sequence, for cerebellopontine angle lesions on a 1.5-T imager (Gyroscan Intera, Philips, Best, The Netherlands). The bFFE MR cisternograms depicted target cranial nerves with less cerebrospinal fluid pulsation artifacts than TSE cisternograms and visualized an acoustic schwannoma in 6 of 44 patients with suspicion and a causative vessel of hemifacial spasm in all of 3 patients in a short scanning time (1 min 53 s). The bFFE sequence can be promising for MR cisternography in the diagnosis of cerebellopontine angle lesions.

Adolescent↗
PubMed2003

MR digital subtraction angiography in the diagnosis of meningiomas.

OBJECTIVE: MR digital subtraction angiography (DSA) is a technique for demonstrating the vasculature combining a rapid two-dimensional T1-weighted sequence with a bolus injection of gadolinium. We attempted to determine its contribution to the diagnosis of intracranial meningiomas. METHODS AND PATIENTS: MR DSA was performed in 18 patients with meningioma as well as in 28 patients with other tumors. The findings were analyzed regarding demonstration of tumor stain and tumor-related vessels. RESULTS: All meningiomas except one were visualized as a homogeneous and intense stain. Feeding arteries were visualized in 2 patients, and draining or abnormal veins in three. In 21 of the 28 patients with other tumors, tumor stains of varying degrees were demonstrated. CONCLUSION: MR DSA can serve as an adjunct to routine MR imaging, because it enables assessment of the hemodynamics of meningiomas and facilitates its differential diagnosis from other tumors.

Adolescent↗
PubMed2003

[Abnormal MR findings in the temporal lobe and basal ganglia along with vasospasm in a case of hemiballism associated with diabetes mellitus].

A 46-year-old woman with a nine-year history of diabetes mellitus (DM) without treatment had an acute onset of right hemiballism. For the treatment of hyperglycemia (random blood sugar 588 mg/dl) conventional insulin therapy was started, and HbA1c rapidly decreased from 16.3% to 8.8% over the first two months. During this period, there were no hypoglycemic symptoms or episodes, though amnesia appeared just after the insulin therapy was started. T1-weighted MRI showed hyperintensity in the left basal ganglia, which has been reported in many cases of chorea or ballism associated with DM. In addition, there were unique changes in the left temporal lobe, including transient contrast enhancement along the cortex followed by transient hyperintensity in the cortical-subcortical area on T2 weighted and FLAIR images, and then hyperintensity along the cortex on T1 weighted images and atrophy. These findings were thought to indicate a consecutive process, i.e., capillary hyperlucency followed mainly by vasogenic edema and then laminar necrosis. Similar MR findings were reported in hypoglycemic coma. MRA also revealed a transient vasospasm in the left MCA M1-M2 portions in this patient. These signal changes may have been related to the prolonged hyperglycemic state as well as blood sugar control that was too rapid.

Basal Ganglia↗
PubMed2002

Application of multi-detector row helical scanning to postmyelographic CT.

The advent of a multi-detector row helical CT has made it possible to attain images over a broader area with good spatial resolution. We assessed whether postmyelographic CT scans obtained using this system provided more information than conventional imaging techniques. Postmyelographic CT scans were preoperatively obtained in 46 patients using a multi-detector row helical CT system. Reconstructed images in the sagittal and coronal planes in all patients and curved reformation images along the dural sac in 37 patients were compared with myelograms and conventional postmyelographic CT scans. In 34 patients comparison was also made with MR images. The multi-detector row CT images demonstrated deformities of the dural sac more clearly than the other modalities in 39 of the 46 patients. They also provided the best visualization of nerve root abnormalities in 24 of the 46 patients and clearly revealed the presence of spurs in all 22 patients with spinal canal stenosis. Postmyelographic CT scans made using a multi-detector row helical CT system provide more information on the dural sac, nerve sleeves, and their contents than other imaging techniques.

Adolescent↗