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Biomedical subjects

K Katada

Publications and source records attributed to K Katada.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Fundamental study of helical scanning CT--evaluation of spatial resolution in the longitudinal axis].

We evaluated spatial resolution in the longitudinal axis with helical scanning CT using a fourth-generation fast CT scanner. We made a phantom by stringing acrylic balls (65 mm phi x 8 and 9 mm phi x 6). The acquired images were processed by MPR and assessed visually to evaluate axis resolution. With the conventional scanning method, the partial volume effect varied with the starting position, but helical scanning was able to reconstruct high-resolution images using continuous raw data. During helical scanning, axis resolution varied depending on the slice width and sliding speed of the couch top. Even if the sliding speed was kept constant at 4 mm/sec, axis resolution was superior with a slice width of 2 mm than with one of 5 mm.

Microcomputers↗
PubMed1991

Quantitative measurement of regional cerebral blood flow with I-123 IMP SPECT: a correction of the microsphere model by global extraction between artery and internal jugular vein.

Quantitative measurements of regional cerebral blood flow with N-isopropyl-(Iodine 123)p-iodoamphetamine (I-123 IMP) as a microsphere model were performed in forty cases. The regional cerebral blood flow values obtained with I-123 IMP were slightly underestimated compared with those of Xe-133 inhalation methods (y = 0.90x-2.1, r = 0.85, p less than 0.01). After correction by global extraction (87%) between the artery and internal jugular vein, which was measured in four patients by means of a catheter technique, the underestimation of the values obtained with I-123 IMP was improved (y = 1.0x-2.4, r = 0.85, p less than 0.01). Several problems in the accurate quantitative measurement of regional cerebral blood flow with I-123 IMP are discussed.

Adult↗
PubMed1991

Effects of calcium antagonists on the erythrocyte membrane.

The effects of dihydropyridine compounds nimodipine, nicardipine and NB818 (isopropyl methyl-6-carbamoyloxymethyl-4-(2,3-dichlorophenyl)-1,4-dihydro-2-methyl- 3,5- pyridine-dicarboxylate) on erythrocyte membranes have been studied. These compounds showed protective effects against hypotonic haemolysis, but not against heat-induced haemolysis. An increase in deformability of erythrocytes by these calcium antagonists was observed using a capillary tube centrifugal method. The erythrocytes showed slight stomatocytosis after 30 min of incubation with calcium antagonists, but did not show significant changes in mean corpuscular volume and ATP levels.

Animals↗
PubMed1990

MR imaging of brain surface structures: surface anatomy scanning (SAS).

MR imaging technique that permits direct and non-invasive visualization of brain surface structures (Surface Anatomy Scanning, SAS) was developed using the combination of long TE, long TR spin echo sequence and thick slice. Clinical trials in 67 patients with SAS showed excellent visualization of the sulci and the gyri on the lateral, occipital, frontal and parietal surfaces of the brain together with cortical and subcortical lesions. The results indicate that the SAS is useful for the localization of cortical and subcortical pathology, for the diagnosis of anomalous gyral patterns, and for surgical planning.

Brain↗
PubMed1990

Cerebral hemodynamics in patients with chronic obstructive carotid disease by rCBF, rCBV, and rCBV/rCBF ratio using SPECT.

To evaluate cerebral hemodynamics, 21 patients with chronic occlusion or severe stenosis of the internal carotid or middle cerebral artery with normal or only lacunar infarction on x-ray CT were studied using single photon emission computed tomography (SPECT). We measured rCBV with 99mTc erythrocytes after rCBF with 133Xe, and calculated rCBV/rCBF. rCBF and rCBV of the 25 affected hemispheres were classified as (a) patients with normal rCBF [type I (n = 7) and type II (n = 3)]; (b) patients with decreased rCBF [type III (n = 6) and type IV (n = 9)]. These two groups then could be subdivided according to findings of rCBV, normal, and increased blood volumes. rCBV/rCBF increased as the cerebral perfusion pressure dropped from type I to type III. In type IV, other situations but cerebral autoregulation could be assumed. rCBV/rCBF signifies vascular mean transit time. Type III (high rCBV/rCBF) assumed as the increased OEF, misery perfusion as reported in PET. We propose rCBF, rCBV and rCBV/rCBF using SPECT can be an index for cerebral circulatory reserve.

Arterial Occlusive Diseases↗
PubMed1990

[Brachytherapy of choroidal melanoma using radioactive gold grains--a case report].

A brachytherapy of a choroidal melanoma using 198Au grains has been performed. Procedurally, the sclera was first incised, after which a pouch was constructed and the grains then arranged around the tumor in a circle so as to enclose it, said operative procedure according to the Manchester Technique. Total Gy dosage amounted to 120 Gy. Postoperatively, in due course, the disappearance of the tumor was clearly shown on MRI examination. The small size and the short half-life of the gold grains made it possible to insert the grains into the tissue permanently, and to give an adequate Gy dosage to eradicate the tumor while still preserving the eyeball.

Adult↗
PubMed1990

[A successful treatment of spontaneous carotid cavernous fistula causing hemorrhagic infarction treated by detachable balloon].

A rare case of hemorrhagic infarction associated with carotid-cavernous fistula is reported. The patient was a 74-year-old female. CT scan showed hemorrhagic infarction of the left superior temporal gyrus, irregular vascular enhancement of the bilateral front-temporal lobe, and dilatation of the cavernous sinus. Left carotid angiogram revealed a high-flow left-sided CCF, cross filling to the right cavernous sinus, and intracavernous aneurysm. Bilateral front-temporal cortical veins were visualized early in the arterial phase. In this case, there was a direct shunt between the internal carotid artery and the cavernous sinus, and venous hypertension. Therefore urgent treatment using detachable balloon catheters was performed. Postoperative digital subtraction angiography revealed the disappearance of CCF. In conclusion, in CCF with cortical venous drainage there is a high possibility of developing hemorrhagic infarction. Only immediate detachable balloon occlusion can improve the outcome in elderly patients.

Aged↗
PubMed1989

[Evaluation of cerebral hemodynamics by 123I-IMP in cerebral AVMs before and after operation by using SPECT].

To evaluate cerebral hemodynamics by N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) preoperative and postoperative (after 1 day, and after 7-10 days) regional cerebral blood flow scan, 6 arteriovenous malformations (AVMs) which performed total removal operations were studied by using a ring type SPECT "HEADTOME". We performed the dynamic scan just after the intravenous injection of 222 MBq (6 mCi) of 123I-IMP, then the static scan 20 minutes after the intravenous injection. In preoperative dynamic scans of all cases, only the first frame image showed the increased activity on the nidus probably because of the blood pool. Preoperative static scans of all cases showed the remarkable decreased activity on the nidus, and decreased activity surrounding the nidus probably because of the peripheral steal phenomenon. In postoperative scan of the next day, 4 out of 6 cases showed the transient decreased peripheral steal, particularly 2 out of those 4 cases showed the transient hyperperfusion probably because of the normal perfusion pressure breakthrough (NPPB). And, 2 out of 6 cases showed transient peripheral low perfusion on much larger area than those of the preoperative scans probably because of the focal brain damages and edemas. We conclude that 123I-IMP SPECT on AVM is very useful to decide the indication of the removal operation, and to estimate the postoperative risk, and to evaluate the preoperative and postoperative cerebral hemodynamic changes in the peripheral area of AVM.

Adolescent↗
PubMed1989

[SPECT measurement of cerebral hemodynamics in transient ischemic attack patients--evaluation of pathogenesis and detection of misery perfusion].

To evaluate the cerebral hemodynamics and the pathogenesis by regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV), 42 transient ischemic attack (TIA) patients and 9 normal volunteers were studied using SPECT. We classified these patients into Group A (n = 23: no occlusion or stenosis of the internal carotid or middle cerebral artery; non large vessel disease) and Group B (n = 19: chronic occlusion or severe stenosis of the internal carotid or middle cerebral artery; large vessel disease). We obtained rCBF with 133Xe inhalation and rCBV with 99mTc-red blood cells. Of 9 normal volunteers aged 43-70 yr (mean age 59.8 +/- 8.3 yr), the mean rCBF was 45.8 +/- 5.1 (ml/100 g brain/min), the mean rCBV was 4.0 +/- 0.4 (ml/100 g brain). The examination was done by comparing the values of the affected hemispheres of Group A and Group B patients with the mean rCBF and the mean rCBV of normal volunteers. Eleven out of Group A patients and 15 out of Group B patients showed decreased rCBF. But of those patients, no patients of Group A showed increased rCBV and 6 out of 19 Group B patients showed increased rCBV. Thromboembolic mechanism which is of Group A patients and Group B patients without increased rCBV, and hemodynamic mechanism which is of Group B patients with increased rCBV were considered as the main cause of TIA. Decreased rCBF and increased rCBV in Group B patients can be assumed as the misery perfusion as reported in PET studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Bilateral giant intracavernous aneurysms. Technique of unilateral operation.

We report a case of bilateral intracavernous giant aneurysms of which the right side was clipped by direct surgery. Our case was a 74-year-old woman who developed bilateral abducens palsy. Computed tomography and angiography showed bilateral intracavernous giant aneurysms. This patient was followed up in the outpatient clinic. She developed headache and right trigeminal neuralgia 2 years later. The trigeminal pain was quite severe and very disturbing to her. Repeat angiography showed an increase in the size of the aneurysms. An operation was carried out after a balloon Matus test monitoring electroencephalogram, somatosensory evoked potential, and clinical symptoms. The cavernous sinus was opened and the aneurysm was clipped. There was no postoperative complication except right ophthalmoplegia which resolved after 3 months. Headache and trigeminal neuralgia also disappeared.

Aged↗
PubMed1987

The treatment of dural AVM by embolization with aron alpha (ethyl-2-cyanoacrylate).

The authors report four cases of dural arteriovenous malformation (AVM) treated by a modified technique of embolization. Three cases had posterior fossa dural AVM and one had bilateral supratentorial dural AVM. The authors think that the best way to treat dural AVM is to close its nidus completely. This could be achieved by a safe and easy technique of embolization. The material used for embolization should intimately adhere to the vascular network and should not become fragmented. We used aron alpha (Ethyl-2-cyanoacrylate). This is a biological glue and it sets in a solid membranous form instantaneously on coming into the contact with an ionic medium. It does not get fragmented. Aron alpha was injected into the nidus of the AVM through a cannula inserted only into the main feeding artery in four cases of dural AVM reported here. Postoperative angiography showed complete obliteration of the AVM's, they did not fill either from the treated artery or from the untreated feeding arteries. The technique is easy and safe. There was no operative or postoperative complication. All the patients have remained asymptomatic to date, i.e. 2, 2, 6 and 7 1/2 years after the procedure.

Adult↗
PubMed1986

Ethyl 2-cyanoacrylate as an embolic agent for cranial arteriovenous malformations. An experimental study.

Physical properties of ethyl 2-cyanoacrylate (Aron Alpha) were studied in comparison with isobutyl 2-cyanoacrylate (IBCA). Aron Alpha is characterized by high viscosity, a short polymerization time, low spreadability and low fragmentability. On the other hand, IBCA had low viscosity, a relatively long polymerization time, high spreadability and high fragmentability. Based on these findings, it is suggested that IBCA is suitable for transcatheter embolization, and Aron Alpha for intraoperative embolization. Mixture of IBCA with 5% Aron Alpha suppressed the spreadability and the fragmentability of IBCA, resulting in reduction of distal migration of IBCA into the venous system.

Adhesives↗