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Biomedical subjects

K Katada

Publications and source records attributed to K Katada.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of new titanium cerebral aneurysm clips on MRI and CT images.

We studied the effects of newly developed aneurysm clips made of a titanium alloy (manufactured by Aesculap, A.G.) on the quality of MR and CT images. Prior to clinical application in twenty patients, the effects of five types of conventional aneurysmal clips on MR images were examined utilizing a phantom. When compared with conventional aneurysm clips, the new titanium clips produce only limited artifacts and yielded improved images in patients who underwent aneurysm clipping post-operative.

Aged↗
PubMed1996

Stereoscopic synthesized brain-surface imaging with MR angiography for localization of a peripheral mycotic aneurysm: case report.

A patient with subacute bacterial endocarditis and a peripheral mycotic aneurysm is presented. We used a combined multi-slice surface anatomy scanning (SAS) and contrast-enhanced MR angiography image to determine the exact location of the small lesion by applying a skin marker on the scalp and visualizing the relationship of the marker to the brain surface structures and to the lesion. This technique was useful for the removal of a small peripheral aneurysm using only a limited craniotomy.

Aged↗
PubMed1996

Clinical usefulness of 3-D CT endoscopic imaging of cerebral aneurysms.

Usefulness of endoscopic imaging of cerebral aneurysms is presented. 3-D luminal images were obtained using a new processing technique which extracts CT numbers in the boundary region between the vessel wall and contrast media filled in the vascular lumen. Clinical application of this technique to complicated large cerebral aneurysms showed that, with this 3-D CT endoscopic imaging, anatomical details of cerebral aneurysms such as the orifice of the aneurysm, intraluminal thrombus, and calcification of the wall could be clearly demonstrated. Using a 3-D imaging method by Helical CT virtual views of various surgical approaches were compared preoperatively. With this technique, not only virtual surgical views of aneurysms and related vasculature, but also surgical views after virtual resection of skull base bone to a desirable extent are freely available. We operated on two large, complicated aneurysms and one broad-based aneurysm after obtaining 3-D CT endoscopic images of the aneurysms. Such information was found to be very useful for determining difficult and complicated cerebral aneurysms and broad-based aneurysms for coil embolization or direct open surgery.

Angioscopy↗
PubMed1996

Guidance with real-time CT fluoroscopy: early clinical experience.

A recently developed real-time computed tomography (CT) fluoroscopy system, which provides effective real-time reconstruction and display of CT images, was used to monitor nonvascular interventional procedures performed in 57 patients. Biopsy of thoracic lesions (n = 38), biopsy or drainage of pelvic lesions (n = 6), drainage or aspiration of intracranial hematomas (n = 9), and other procedures (n = 4) were performed. CT fluoroscopy successfully depicted the entire procedure in all patients. In thoracic lesions, a mean 1.3 passes was necessary to gain access to the lesion. Sufficient cytologic samples were obtained in 32 of 33 pulmonary lesions with a mean diameter of 26 mm.

Adult↗
PubMed1996

Radiation dosimetry at CT fluoroscopy: physician's hand dose and development of needle holders.

The radiation dose to physicians' hands without and with use of needle holders was determined at 10 computed tomography (CT) fluoroscopy-guided transthoracic needle biopsies. As measured with ionization chambers (tube voltage, 80 kVp; tube current, 30 mA), the mean absorbed dose rate without and with holders was 1.14 mGy/sec +/- 0.02 (standard deviation) and 0.019 mGy/sec +/- 0.001, respectively. The mean duration of CT fluoroscopy was 59 seconds in 10 biopsies performed with a holder and 82 seconds in 10 biopsies performed without a holder (difference not statistically significant). The needle holders did not cause any artifacts that interfered with the biopsy procedure.

Biopsy, Needle↗
PubMed1996

[Evaluation of the clinical usefulness of super dynamic 99mTc-HM-PAO SPECT in ischemic cerebrovascular disease--detection of hypo- and hyperperfusion area].

The purpose of this study is to assess the clinical usefulness of super dynamic SPECT of 99mTc-HM-PAO. Six patients with unilateral occlusion of middle cerebral artery (MCA) or internal carotid artery (ICA) in the chronic phase, and 5 patients with subacute cerebral infarction were studied. We used a ring-type SPECT "HEADTOME." Two types of collimator were used: a high sensitivity (HS) collimator for super dynamic scan and a high resolution (HR) collimator for static scan. First, the intravenous constant infusion of 99mTc-HM-PAO (925-1480 MBq) for 1 minute was started. After 30 seconds from the beginning of the injection, we performed the 12 seconds/frame super dynamic SPECT for 2 minutes. Then, the static SPECT for 10 minutes was done. For semiquantitative analyses, differential percentage of regional activity between affected and non-affected hemispheres was calculated in the 6th frame image of super dynamic SPECT and static SPECT image. In all 6 patients with unilateral occlusion of MCA and ICA, super dynamic SPECT images showed the better contrast of low perfusion areas in comparison with the static SPECT images. In 5 patients with subacute cerebral infarction who showed focal hyperactivities on static SPECT, focal hyperactivities (hyperperfusion or hyperemia) were displayed in 3 cases, whereas, focal hypo- or isoactivities (hypo- or isoperfusion) were shown in 2 cases on super dynamic SPECT. However, all patients with subacute cerebral infarction showed hyperfixation on static SPECT as compared with super dynamic SPECT. Although the image quality on super dynamic SPECT is not as high as that on static SPECT, cerebral hemodynamics would be detected with less backdiffusion of 99mTc-HM-PAO from the brain to blood, and with less accumulation of hydrophilic components in subacute infarct region. In conclusion, super dynamic SPECT in early distribution of 99mTc-HM-PAO using dedicated SPECT device might be helpful to detect cerebral perfusion close to true cerebral blood flow distribution.

Aged↗
PubMed1995

Usefulness of simulation of surgical approaches to cerebral aneurysms by helical scanning CT (HES-CT).

Using multiplanar reconstruction (MPR) CT imaging method, virtual views of various surgical approaches were compared preoperatively. With this technique, not only virtual surgical views of aneurysms and related vasculature, but also surgical views after virtual resection of skull base bone to a desirable extent are freely available. We operated four aneurysm cases after comparing various surgical approaches by this imaging method. It was found that these preoperative simulated images were very useful at surgery of complicated aneurysm cases.

Adult↗
PubMed1995

Integrated life-sized solid model of bone and soft tissue: application for cleft lip and palate infants.

The recent development of three-dimensional computed tomography (3D-CT) and laser stereolithography has allowed the creation of life-sized skeletal models. The development of helical CT has enabled us to apply this method to very young children. However, skeletal models alone do not reveal the spatial relationship between soft tissue and bone in complicated craniofacial deformities. We have therefore developed a model that shows both soft and bony tissue by first using CT values that result in a model in which soft tissue is solid and bone is replaced by empty space. The space is then filled with plaster to represent the skeleton. This model also can provide baseline data for evaluating facial growth after surgical repair of clefts. Two infants with cleft lip and palate are presented to illustrate this method of creating an integrated solid model and its applications.

Bone and Bones↗
PubMed1995

[Clinical usefulness of 3-D CT endoscopic imaging of cerebral aneurysms].

Usefulness of endoscopic imaging of cerebral aneurysms is presented. 3D-luminal images were obtained using a new processing technique which extracts CT numbers in the boundary region between the vessel wall and contrast media filling in the vascular lumen. Clinical application of this technique to complicated large cerebral aneurysms showed that, with this 3D-CT endoscopic images and MRA, anatomical details of cerebral aneurysms such as the orifice of the aneurysm, intraluminal thrombus, and calcification of the wall could be clearly demonstrated. We operated on two large, complicated aneurysms after obtaining 3D-CT endoscopy images of the aneurysms. Such information was found to be very useful when operating on difficult and complicated cerebral aneurysms.

Artifacts↗
PubMed1995

[Clinical usefulness of helical-scanning CT for the evaluation of arteriosclerotic carotid lesions].

We examined arteriosclerotic carotid lesions in 76 patients using helical scanning CT (HES-CT), and evaluated the clinical usefulness of this method. A high speed slip-ring X-ray CT system was used. Scanning of the neck was performed for a 30 second period following intravenous bolus injection of non-ionic contrast medium, while couch top movement was 2.0 mm/sec. Multiplannar reconstruction images (MPR-image) and 3-dimensional surface images (3D-image) were reconstructed from the continuous raw data. MPR-images offered axial, coronal and sagittal images in which the lesion could be seen from any direction, and 3D-images that could be freely rotated were obtained by using a track ball and monitor. Eighteen cases were also evaluated by conventional angiography. Excellent HES-CT images were obtained in 73 cases, showing occlusion in 13, stenosis in 34, plaques without calcification in 15 and plaques with calcification in 74 vessels. A good correlation was obtained between HES-CT and angiogram in most cases, and in 6 cases, HES-CT was superior in the detection of stenosis, because it enabled us to observe the lesion from various directions. These results suggested that HES-CT was a minimally invasive, useful diagnostic method for the evaluation of arteriosclerotic carotid disease.

Arteriosclerosis↗
PubMed1994

[Development of real-time CT fluoroscopy].

A new CT system that permits real-time monitoring of CT images was developed. Phantom and volunteer studies revealed that the images were displayed at a rate of six per second with a delay time of 0.83 second with clinically sufficient resolution (256 x 256) using the newly developed fast image processor and partial-reconstruction algorithm. The clinical trial of stereotactic aspiration of intracerebral hematoma was successful. The initial trial with CT fluoroscopy revealed potential usefulness of the system in biopsy and other CT-guided interventions.

Biopsy, Needle↗
PubMed1994

[Detectability of cerebral aneurysms and surrounding vessels by three-dimensional evaluation using helical scanning CT (HES-CT)].

Helical scanning CT (HES-CT) is a new technique to enable high-speed volumetric data acquisition. We have applied HES-CT to the diagnosis of cerebral vascular diseases. In our experience, the relationship between the scanning parameters of HES-CT and image quality was complex and reciprocal, so that optimization of the parameters according to the clinical demands was essential. We compared HES-CT with conventional cerebral angiography to determine the detectability of the aneurysm and surrounding vessels, and sought the optimal parameters to delineate small vessels. All aneurysms were detected in multiplanar reconstruction (MPR) images. The smallest one was 3 x 4 mm. MPR images were found to have some advantages over conventional cerebral angiography in delineation of intracranial aneurysms: 1) scanning was over in a short time (30s), 2) the relationship between the aneurysm and surrounding vessels was easily recognized, 3) the diameter of the neck could be measured, because the neck of the aneurysm and parent artery could be imaged on the same plane without overlapping another vessel, 4) calcified lesions on the aneurysmal wall were detected, and 5) HES-CT was done safety without arterial puncture. However, the detectability of unknown aneurysm was less than the detectability of known aneurysm in MPR images. The 180 degrees interpolation algorithm and 1 mm slice were effective in detecting small vessels. However, vessels with a diameter less than 1 mm could not be detected by HES-CT. HES-CT was considered to be useful as a supplementary examination to conventional angiography for the diagnosis of intracranial aneurysms.

Adolescent↗
PubMed1994

Evaluation of regional cerebral blood flow changes on perifocal brain tissue SPECT before and after removal of arteriovenous malformations.

In fifteen cases of arteriovenous malformation (AVM), serial examinations of regional cerebral blood flow (rCBF) using single photon emission computed tomography (SPECT) and N-isopropyl-(123I)p-iodoamphetamine were performed. On SPECT images, the nidus was visualized as a focal rCBF defect in all cases preoperatively and seven of these cases had abnormal decreased perfusion areas in the tissues adjacent to the nidus. In five cases, the postoperative SPECT images on the day after surgery revealed an abnormal increased perfusion area adjacent to the nidus and in one case the increased perfusion was accompanied by a massive intracerebral haemorrhage detected by brain computed tomography (CT). In seven cases, postoperative SPECT images showed widespread abnormal decreased perfusion areas in the surrounding tissues and brain CT revealed either intracerebral haemorrhage or significant cerebral oedema. In the other three cases, no remarkable rCBF changes were found in comparison with the pre-operative study. There was a tendency for the preoperative abnormal decreased perfusion area adjacent to the nidus to correlate with the postoperative hyperperfusion and for the postoperative abnormal decreased perfusion area to reflect brain damage.

Adolescent↗
PubMed1993

[A case of anaphylactic shock following the administration of Gd-DTPA].

We experienced a case of serious adverse reaction following the administration of Gd-DTPA (gadolinium with diethylenetriamine pentaacetic acid). The patient showed sneezing and hoarseness when Gd-DTPA was administered for the first time. At the second injection, when hydrocortisone was used in advance to prevent allergic reaction, she lapsed into a pre-shock state and anaphylactic reaction was strongly suggested by the laboratory data. The possibility that Gd-DTPA may cause the severe side effects must be noted.

Adult↗
PubMed1993

[An application of dynamic CT for diagnosis of abnormal external ocular muscle movement].

To evaluate the movements of retrobulbar structures radiologically, we have developed a new technique called "external ocular muscle movement CT" (EOM CT), in which dynamic CT scanning is performed while the patient performs controlled eye movements. This new technique was applied in one volunteer and 72 patients with external ophthalmoplegia due to orbital mass lesion, hyperthyroid ophthalmopathy, blowout fracture, and other retrobulbar lesions. EOM CT permits the assessment of extraocular muscle contraction in cases of blowout fracture, the evaluation of muscular contraction in hypertrophy of the extraocular muscles, and the diagnosis of adhesions between the extraocular muscles and intraorbital masses. Radiation dose to the lens from EOM CT was measured using a phantom and TLD, and was compared with that of conventional CT scanning with a 5 mm slice thickness. The dose to the lens from EOM CT was three times higher than that for conventional CT in axial scanning, but in the coronal section of the retrobulbar region, the dose to the lens from EOM CT decreases to one twelfth that of conventional CT. EOM CT promises to be a powerful modality for functional evaluation of the extraocular muscles and other retrobulbar structures.

Adolescent↗
PubMed1993

[Visualization of coronary arteries with helical scanning CT: diastolic reconstruction].

The purpose of this study was the visualization of coronary arteries by the diastolic reconstruction method with helical scanning (HES) CT. We chose diastolic phase images from the image data acquired with the HES technique using a continuous nutate-rotate fast CT scanner, because few motion artifacts are induced by cardiac pulsation during the slow filling diastolic phase. We assessed coronary diseases using this method based on HES-CT, and evaluated its clinical effectiveness. We also studied the clinical value of multiplanar reconstruction and three-dimensional surface reconstruction. The subjects consisted of 31 patients with coronary disease, aged 41-77 years. When a diastolic reconstruction HES-CT was employed, the average rate of visualization of the coronary arteries was 72%. An examination can be completed during a 30-second single breath-hold, permitting the acquisition of coronary artery images with excellent continuity. Calcified coronary arteries can be identified.

Adult↗
PubMed1993

[Clinical usefulness of helical scanning CT (HES-CT) for orbital lesion].

Helical scanning CT (HES-CT) was applied to multiplanar reconstruction (MPR) and 3-D imaging for the diagnosis of 65 patients with orbital lesions. We employed the the Toshiba TCT-900S, a fourth-generation high-speed CT scanner equipped with a slip-ring system. In HES-CT, scanning was performed with continuous rotation of the X-ray tube for 30 s, while the couch top was simultaneously moved at a constant speed of 1 to 2 mm/s. Images were reconstructed from continuous raw data to obtain a slice pitch of 1 mm in the longitudinal direction. HES-CT was found to have some advantages over conventional thin slice CT: 1) a wide area could be scanned in a short time (30 s) without motion artifact, 2) small lesions could be easily detected because slice images could be generated with a fine pitch at arbitrary positions from continuous raw data, 3) MPR images had good continuity in the longitudinal direction, and 4) high contrast of structures was obtained in the orbital region. HES-CT was considered to be useful for the detection of orbital lesions.

Child↗