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H Oyamada

Publications and source records attributed to H Oyamada.

At least 127 records · Page 7Linked to original sources
PubMed1982

A combined method of scintigram and echogram as a trial of integrated image diagnosis.

We developed a method which combines a scintigram and echogram(s) on the basis of precise positional correlation. In our method, an ordinary scintillation camera (Ohio Nuclear sigma 410S) and an ultrasound diagnosis equipment (Aloka Echo Camera) are used, both of which are connected through the interface made by us. This method presents a scintigram with dotted lines through which echograms have been taken, giving us more detailed inside information which we can not obtain from scintigram only. Also obtained are positional correlations between the organ of interest and its neighbouring organs. This method is easily applicable to ordinary scintillation cameras and is useful for our daily practice.

Aged↗
PubMed1981

[Basic studies on radionuclide computed tomography using a rotating chair (author's transl)].

Radionuclide Computed Tomography (RCT) was studied from the technical standpoint of view. In this study, a gamma camera (Ohio Nuclear sigma 410S) and a rotating chair designed by one of us were used. The computer used was Scintipac 1200 (32 kW memories and 2.4 MB X 2 disk memories). A cylindrical phantom having a diameter of 20 cm was also designed by us into which various-sized tubes could be inserted for resolution study. The phantom was set on the chair, the center of which was 20 cm off from the surface of the detector. The chair was rotated manually 10 degrees, and finally 36 digital images in the form of 64 X 64 elements were obtained, covering an entire circumference. RCT images were displayed in the form of 128 X 128 elements on a X-ray film through a Microdot Imager. At first, the phantom was filled with 99mTc solution and the uniformity of the RCT image on it was checked using several formulae for count rate correction to find out which one of the formulae was best fitted. For the reconstruction of the RCT image, "filtered back projection" was used. Then, we found that, as far as out phantom study was concerned, simple geometrical mean on the data from the two opposing directions was found the best for the count rate corrections, which was exclusively used thereafter. The fluctuation on the uniform source was found to be approximately 15%. For the resolution study, hot tubes having diameters of 1.0, 2.0, 3.0, and 4.0 cm and cold tubes of 1.5, 2.4, 3.5, and 4.7 cm were inserted into the phantom. As for the hot tubes, all the tubes were depicted on the RCT image whereas 2.4 cm was the smallest depicted for the cold tubes. FWHM was checked with a fine line source in the phantom and was found to be 2.0 cm regardless to its depth. The Alderson liver phantom was also used to detect defects in the air and it was found both balls having diameters of 2.7 and 3.7 cm could be depicted on the RCT image. Now we are evaluating clinical usefulness of this technique on the liver. The results will be published in the near future.

Evaluation Studies as Topic↗
PubMed1980

Clinical significance of abnormal accumulations found in the vertebrae on the bone scintigram of cancer patients.

From January 1975 to December 1976, 180 cancer patients were found to have abnormal accumulations in the vertebrae on their bone scintigrams. These patients were carefully surveyed through their clinical records for more than two years follow-up, x-ray pictures, and autopsy findings; and finally 115 patients were selected for this study. Abnormal accumulations were classified into two categories; significantly positive and equivocal. Among thses 115 patients, significant accumulations were found in 85, and equivocal in 17. The remaining 13 showed both significant and equivocal accumulations. In 81 out of 98 (85 + 13) patients, the significant accumulations were due to metastases; and in 15 out of 30 (17 + 13) patients, the equivocal accumulation only are taken into consideration, the true positive cases are only 3 of the 17. The major factor for false positive was degenerative changes of the vertebrae in either group of significant or equivocal accumulations. Although it is difficult to differentiate benign changes of the vertebrae from the metastases on the bases of scintigram findings only, a cushion-like pattern in disc degeneration as well as in colapse of the vertebral body, a vague concentration with indistinct margin in spondlyosis deformans, and symmetrical accumulations in the intervertebral joints due to sclerotic changes are helpful in evaluating the bone scintigram of cancer patients, together with the site of abnormal accumulation and the age of the patient.

Adult↗
PubMed1980

99mTc-PI as safe and easy scintigraphy after hepatectomy.

Hepatobiliary scintigraphy with 99mTc-PI was performed on 16 patients after various types of hepatectomy for either primary or secondary liver tumor. 99mTc-PI scintigraphy was found very useful, especially in regard to clinical evaluation of indistinct low-uptake areas observed on a 99mTc colloid liver scintigram in the regenerating liver after hepatectomy. Both tests were conducted successively within a couple of weeks. Colloid scintigrams after hepatectomy were divided into two groups according to the sites of indistinct low-uptake areas; one showed them near the resected margin of the regenerating liver (Type I), and the other showed them in both marginal and intrahepatic. regions (Type II). Of these 16 patients, 8 showed Type I and 7 showed Type II. The remaining one was excluded for postsurgical complications. By comparing the colloid scintigram with the 99mTc-PI scintigram, in all the cases of Type I indistinct low-uptake areas were found to be the hilum with a shifted common bile duct. On the other hand, in 2 cases of Type II indistinct low-uptake areas were caused by the hilum accompanied by the dilated bile ducts. In the remaining 5, indistinct low-uptake areas were not identified as bile ducts but were confirmed to be a recurrence of the tumor.

Adult↗
PubMed1980

[Gamma dose estimation to the gastric wall after administration of a capsule containing a large dose of 131I (author's transl)].

Gamma dose to the gastric wall from a capsule containing 1.85 GBq (50 mCi) of 131I was estimated in 6 patients who had received total thyroidectomy for thyroid carcinoma some years before. The tests were done with a 37 MBq (1 mCi) capsule each in 5 patiens and with a 185 MBq (5 mCi) capsule in one patient. All the patients were requested to fast in the morning. The capsule was given with a glass of water (200 ml). Then, the patient kept supine position under the scintillation camera for a period of one hour except one patient on whom the test was suspended at 30 minutes because of early clearance of the radioactivity from the stomach. In one of 5 patients who were tested for a period of one hour, serial scinticamera images showed almost no movement and minimum dissolution of the capsule. The remaining 4 patients showed slight to moderate movements of the capsules with a variety of dissolution speeds. Data processings were done by Scintipac-1200. The estimated doses at the distance of 0.5 cm from the source were 3.820, 2.074, 1.445, 1.154 and 1.462 grays (382.0, 207.4, 144.5, 115.4 and 146.2 rads) per initial one hour and 375 mGy (37.5 rad) per initial 30 minutes, respectively. From these data, it is thought to be wise to advise the patient to rotate or shake the body on bed occasionally after swallowing the capsules containing a large dose of 131I for the treatment of thyroid cancer. It is also desirable to recommend the patient to walk around even though the controlled patient's room is small. Additional water may be also meaningful to avoid unnecessary irradiation to the gastric wall.

Adult↗
PubMed1980

Subtraction scintigraphy with 67Ga-citrate and 99mTc-colloid in the diagnosis of intrahepatic masses.

Subtraction scintigraphy of the liver with 67Ga-citrate and 99mTc-colloid (99mTc-phytate) was performed by subtracting the image of the latter from the image of the former in 34 patients who were suspected of having intrahepatic masses, especially hepatoma. The computer used was Scintipac 1200 (32 KW memories and 2.4MBX2 disk memories). Both images were taken in a digital form (128 X 128 elements). After normalizing both images, 4 different factors (0.6, 0.8, 1.0, and 1.2) were applied to the 99mTc image before the subtraction from the 67Ga image. We found that this technique was very useful for the detection of abnormal 67Ga accumulation in the liver.

Adult↗
PubMed1978

Whole body bone scintigram and stage classification of the patients with adenocarcinoma of lung.

One hundred and six patients having adenocarcinoma of the lung were studied by whole body bone scanning with 99mTc-phosphates in connection with their clinical stages. Abnormal accumulation was found in 64 patients (60%). There were 64 patients who received surgical treatment. Among these 64 patients, 38 underwent bone scanning within 3 months after the establishment of their clinical stages. Twenty-two of them were classified as Stage I clinically. Pathological stage classification after the surgery revealed these 22 to be classified into 3 groups; 6 for Pathological Stage I, 4 for Pathological Stage II and 12 for Pathological Stage III. None of these 6 in Stage I showed abnormal accumulations. However, 1 of 4 in Stage II and 6 of 12 in Stage III were found to have abnormal accumulations. Therefore, if bone scintigrams had been taken into consideration for clinical stage classification, 7 patients would have never been placed into Clinical Stage I and could be expected more precise treatment. The authors recommend application of the results of whole body bone scanning to stage classification of adenocarcinoma of the lung. Needle biopsy is also recommended to confirm the metastasis at the site of radioisotope accumulation in the rib.

Adenocarcinoma↗
PubMed1977

Scintigraphic evaluation of cold thyroid nodules.

Scintagraphic patterns of cold thyroid nodules taken by the scintillation camera with radioactive iodine-131 were reported. Previous reports published by others on this subject were based on the scintillation scanner which gave us less sharp resolution than the scintillation camera. Our data indicate that the defect pattern is largely dependent upon the existence of the capsule as well as the size of the nodule. In general, a benign nodule shows defect having a rather smooth margin with somewhat distended normal thyroid tissue, whereas malignant one, if it has no capsule, shows an irregular or straight margin. However, the defect pattern of malignant nodule covered with a capsule is similar to that of benign nodule. A defect of the entire unilateral lobe and highly irregular-shaped defect spread over bilateral lobes are suggestive of malignancy. These findings seem to be generally similar to those reported by others. However, pull-up phenomenon of lower pole coexisting with the defect in the upper half is highly suggestive of malignancy, especially of papillary type. As long as defect (negative) pattern is investigated, the diagnosis of cold nodule inevitably meets certain limitations. To avoid this problem, the radiopharmaceutical which exclusively concnetrates in malignant nodule should be searched. Then, the scintigraphic diagnosis of thyroid nodule will become more reliable.

Adenoma↗
PubMed1976

Bone scanning with 99m-Tc-phosphates: a comparison and problems in the detection of tumor metastasis.

A comparative study on 99m-Tc-phosphate compounds (TcPP) in detecting tumor metastasis to bone and problems accompanying it are reported. TcPP revealed metastatic foci which are unrecognized by conventional bone survey. To recognize these foci, exclusion of following problems is necessary: Accumulation at front of neck, asymmetrical image of joint, increased bone density of the aged, Tc-photon absorption and radiotherapy effect. The mechanism of TcPP accumulation is discussed.

Absorption↗