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Biomedical subjects

Y Takaki

Publications and source records attributed to Y Takaki.

At least 55 records · Page 3Linked to original sources
PubMed1993

Quantification of renal uptake of technetium-99m-DTPA using planar scintigraphy: a technique that considers organ volume.

We developed a method to estimate the radioactivity of 99mTc-DTPA within the kidney by planar scintigraphy. Phantom experiments and renal studies were used to compare our method with that of the Gates' method. Our method corrects for scatter and attenuation using the volume depth-independent buildup factor technique, after which background correction is performed with consideration for target organ volume. When the renal phantom-to-background activity concentration ratio (S) was changed from 5 to 80 in a water-filled container and the renal phantom depth was varied from 1 to 11 cm for each value of S, the renal phantom count rate calculated by our method was accurate under all conditions investigated. In contrast, the Gates' method was significantly affected by phantom depth and S values. In 40 patients, renal uptake in the image obtained 2-3 min after injection of 99mTc-DTPA was estimated by our method and the Gates' method, and the correlation between uptake and creatinine clearance was determined. When a ring background region of interest (ROI) around the kidney was employed, a good correlation was obtained by our method (r = 0.947) in comparison with the Gates method (r = 0.887). With both methods, a semilunar background ROI produced poor results than the ring background ROI. In conclusion, renal radioactivity levels that correlate well with creatinine clearance can be obtained by our method, which allows estimation of individual glomerular filtration rates.

Female↗
PubMed1993

[Acute cardiac tamponade in nonpenetrating injury of proximal aorta: report of a case].

A 21-year-old male admitted to the emergency room with multiple traumatic injuries and shock. Although a chest X-ray showed normal in size of cardiac shadow, echocardiography confirmed cardiac tamponade. A median sternotomy was performed and the pericardial space was evacuated of 600 ml of blood and blood clots. Minor bleeding was identified in the proximal aorta, and complete hemostasis was achieved with manual compression and fibrin glue sealing. One month follow-up showed no pseudoaneurysm formation.

Adult↗
PubMed1992

Correction of scattered photons in Tc-99m imaging by means of a photopeak dual-energy window acquisition.

We are proposing a new method for correcting of scattered photons in technetium-99m (99mTc) imaging by means of photopeak dual-energy window acquisition. This method consists of the simultaneous acquisition of two images and estimation of a scatter image included in the symmetric energy window (SW) image by the difference between these images. The scatter corrected image is obtained by subtracting the scatter image from the SW image. In order to evaluate this method, we imaged a planar and a SPECT phantom with cold lesions and calculated the contrast value with and without the scatter correction. In addition, we performed asymmetric energy window (ASW) imaging to compare with this scatter correction method for planar images. In the planar image with the tissue-equivalent material of 10 cm, the scatter correction method removed 32% of the counting rate of the SW image and improved from 0.81 to 0.94 of the contrast value for a 4 cm-diameter cold lesion, while the contrast value with the ASW was 0.87 for such a cold lesion. The scatter corrected SPECT image had a reduction of 18% of the counting rate of the SW SPECT image and improvement of approximately 11% in contrast for cold spot sizes larger than a 3 cm-diameter, compared with the SW SPECT image. In addition, a perfusion defect could be well visualized by this scatter correction method on 99mTc-HMPAO regional cerebral blood flow SPECT of a patient. Our proposed scatter correction method can improve both planar and SPECT images qualitatively and quantitatively.

Brain Concussion↗
PubMed1992

Decreased perfusion in myocardial region of normal donor artery secondary to collateral development. Stress 201Tl myocardial emission CT performed in patients with single vessel exertional angina having collaterals.

Thirty-one patients suffering from single vessel exertional angina with collaterals (Group A) were evaluated by stress 201T1 myocardial emission CT (Tl-SPECT) with 16 controls of severely stenotic single vessel exertional angina without collaterals (Group B). Group A included 21 patients (68%) who showed an extensive perfusion defect in double artery myocardial regions, including the normal donor artery myocardial region (DMR). However, there were no such cases in Group B, giving a significant difference between these 2 groups (p less than 0.001). Four patients in Group A, having a perfusion defect both in DMR and in the collateral dependent myocardial region (CMR) underwent a successful percutaneous transluminal coronary angioplasty (PTCA) with disappearance of collaterals. Tl-SPECT findings after PTCA showed no perfusion defect either in CMR or in DMR. This has been explained on the basis that the coronary collaterals stole blood and produced perfusion defect in DMR.

Aged↗
PubMed1989

[Percutaneous transluminal renal angioplasty: indication for renovascular hypertension associated with renal atrophy].

The results of clinical studies indicate that percutaneous transluminal renal angioplasty (PTRA) is an effective means for treating renovascular hypertension resulting from renal artery stenosis. However, the indications for the patients with renal failure or renal atrophy are not established on a firm ground. We attempted PTRAs of ten kidneys in nine patients with hypertension associated with renal atrophy. They were followed for an average of 8 months by the methods including blood pressure, angiography or DSA, blood chemistry, and RI-renogram. We also evaluated enlargement of the renal size on an angiogram or on a plain film at DSA. Angiographic follow-up showed persistent relief of the stenosis in all cases. After PTRA, blood pressure reduced to normal or improved in two thirds of the patients for the follow-up period. In the study of three patients with excellent results for blood pressure, two patients showed the renal length to be increased by 1.0 cm or more, and one patient by 0.5 cm. In the same group, RI-renogram also showed good response. These data indicate that PTRA could improve total perfusion on the affected kidneys. On the other hand, in three patients with no change in blood pressure, there was poor response in both the renal size and the data of RI-renograms. We suggest that the irreversible changes might have occurred in these kidneys. It was difficult to predict cure group from no change group before PTRA.

Adult↗
PubMed1989

Spontaneous tumors in F-344/Jcl rats.

The age-related incidence of spontaneously occurring neoplastic and non-neoplastic lesions in untreated F-344/Jcl rats, used as controls in carcinogenicity testing, were studied from the histological examination of tissues from 469 males and 354 females. The incidence of spontaneous tumors was 83.2% in the males and 71.2% in the females. The most common neoplasms were leukemia (males: 24.3%, females: 24.0%), pituitary adenoma (males: 16.0%, females: 45.2%), pheochromocytoma (males: 14.7%, females: 7.3%), testicular interstitial cell tumor (males: 79.1%), and uterine endometrial stromal polyp(females: 16.4%). The incidence of other tumors of almost all the organs and/or tissues was low. Non-neoplastic lesions generally increased with advancing age of the animals.

Age Factors↗
PubMed1986

Radiologic demonstration of Caroli's disease: a case report.

Since the first report by Caroli et al., there have been several reports dealing with Caroli's disease or multiple communicating cysts of the biliary tree. Recently, the usefulness of computed tomography, endoscopic retrograde cholangiopancreatography, ultrasonography, and radionuclide scintigraphy have been emphasized for evaluation of this condition. This report describes a case of Caroli's disease and emphasizes the value of ultrasonography in the evaluation of this condition.

Bile Duct Diseases↗
PubMed1983

Primary malignant fibrous histiocytoma of the endometrium.

Malignant fibrous histiocytoma (MFH) has become one of the most common malignancies occurring in soft tissue. To our knowledge, the present case is the first of MFH occurring in the endometrium. The uterus removed from a 47-year-old woman demonstrated a large multinodular endometrial lesion with gross invasive foci in the myometrium and the left oviduct. Microscopically, the endometrial tumor and the invasive lesions were composed of dense sheets of markedly pleomorphic cells consisting of fibroblast-like cells, histiocyte-like cells, foamy histiocytes, benign appearing multinucleated giant cells resembling either osteoclasts or Touton giant cells, and bizarre tumor giant cells. Some of the tumor cells showed phagocytic activities. The tumor cells were oriented in a random or haphazard fashion and classical storiform and fascicular patterns were not observed. The tumor was diagnosed as MFH consisting exclusively of so-called pleomorphic pattern. The patient is alive without evidence of disease, months following total hysterectomy and bilateral salpingo-oophorectomy.

Female↗
PubMed1977

Immunological studies of pityriasis rosea (Gibert).

In order to elucidate the immunological mechanism in the pathogenesis of pityriasis rosea, immunofluorescent studies were performed on sera obtained from forty patients with this disease. Antibodies against the cytoplasm of normal human epidermal cells were demonstrated in the sera of all patients. The antibody titer showed a tendency to increase within 3 weeks after onset of secondary eruptions and then to decrease gradually until the period of recovery. The immunoglobulin class was determined to be IgM. Furthermore, by the direct immunofluorescent technique, deposits of IgM in the epidermal cells of skin lesions were demonstrated in 3 of 6 herald lesions and in 1 of 4 secondary eruptions. It is suggested that anti-cytoplasmic antibodies produced by some unknown cause may induce the development of secondary eruptions of this disease.

Antibodies↗
PubMed1976

Cytolytic degeneration of keratinocytes adjacent to Langerhans cells in pityriasis rosea (Gibert).

Unique cytolytic degeneration of keratinocytes adjacent to Langerhans cells was observed in five cases of pityriasis rosea (Gilbert). In the cytolytic area, the normal keratinocyte structures were absent except for free ribosomes. In addition, a similar cytolytic part of a keratinocyte was enveloped by the elongated dendrites of the Langerhans cell and was detected within its cytoplasm. The significance of these findings is discussed with respect to anticytoplasmic antibodies in the sera of patients with pityriasis rosea.

Cell Membrane↗