Hiyoshimaru Oyamada

Analysis of thyroid carcinoma based on material registered in japan during 1977-1 986 with special reference to predominance of papillary type

Background. As geographic differences have been observed in the characteristics of thyroid carcinoma, an analysis was made on thyroid carcinoma in the iodine rich country of Japan.

An evaluation of the mediastinal lymphoscintigram for carcinoma of the esophagus studied with 99mTc rhenium sulfur colloid

Lymphoscintigraphies of esophageal carcinoma in nine patients were studied with the aid of 99mTc-labeled rhenium sulfur colloid (99mTc-Re). 99mTc-Re was injected into the submucosal layer of the esophagus (just above the oral side of the tumor) using an esophagoendoscope, 1 or 2 days before operation. Lymphoscintigraphies at intervals of 1, 3, and 20 h after the injection were performed. After that, the region and the number of the visualized (hot) nodes were assessed. After the operation the lymph nodes were dissected and the hot nodes were determined by scintiphotography. The dissected nodes were then studied histologically. A total of 106 nodes were removed from the mediastinum of nine patients. Histologically, metastases were found in 12 of 106 nodes. Twenty six of 106 (24.5%) could be observed visually on the scintigram and 80 (75.5%) could not. Among the visualized (hot) nodes, 34.6% were positive for metastasis. On the other hand, among the novisualized, so-called cold, nodes, only 3.8% were positive for metastasis. Hot nodes of the esophagus indicate a high percentage probability of metastatic nodes.

Segmental assessment on ordinary scintigrams and SPECT images of the liver

By examining the area of defect elucidated on the scintigrams and SPECT (single photon emission computed tomography) images, the extension of the tumor into segments was assessed in cases where the SOL (space-occupying lesion) was determined by other methods. In this study, we followed the Couinauds segmentation. As a result, it was found that the segment with a SOL could be diagnosed fairly well on radionuclide images. Some incorrect assumptions were also found about the segments on ordinary scintigrams in previously published articles. These incorrect assumptions have been accepted for a long time. Although we do not deny that TCT (transmission X-ray computed tomography), echography, angiography, etc. are necessary for a precise judgment on liver segment and also that there are some cases in which the segmental assessment of these radionuclide images is impossible, we do believe that this kind of effort will improve the diagnostic capability of the radionuclide images.

Influence of Unit Voxel Size of Cumulated Radioactivity Distribution on 3D Absorbed Dose Estimates.

内用療法において, 標的領域の三次元絶対吸収線量分布の正確な評価は, ボクセルを基本とした計算アルゴリズムに基づいて, すでに著者らによって開発された3D DOSE MATRIX法を用いて行い得る。本研究の目的は, β線放出核種の累積放射能分布の単位ボクセルの大きさが三次元絶対吸収線量評価に及ぼす影響を明らかにすることである。種々のβ線放出核種 (32P, 90Y, 131I, 186Re, 188Re) が均等に分布していると仮定した標的領域として, 立方体ファントム (24×24×24mm, 32×32×32mm, 48×48×48mm) およびMIRD甲状腺ファントムを使用してコンピュータシミュレーションを行った。種々の単位ボクセルサイズ (1×1×1mm, 4×4×4mm, 8×8×8mm) から成るそれらのファントムに対する最大, 平均および最小吸収線量が開発した3D DOSE MATRIX法を用いて評価された。種々の単位ボクセルサイズから成る標的領域の三次元累積放射能分布がたがいに同一ならば, 標的領域の最大および平均吸収線量は, 単位ボクセルサイズに依存しなかった。しかし, 最小吸収線量は, 単位ボクセルサイズが大きくなるにつれ過大評価された。

Experimental study on the collimator for increasing the resolution of N-isopropyl-p-(123I)iodoamphetamine (IMP) SPECT imaging of the brain.

This study was carried out to design a new collimator for the present 123I-IMP SPECT imaging of the brain, which is hindered by the contamination of 124I and 126I. In this study we intended to increase spacial resolution along the transaxial direction and, at the same time, to compensate for the decrease of sensitivity by sacrificing the resolution along the axial direction to some extent. For this purpose, we developed 4 kinds of slat type units; ultrahigh resolution (UHR), high resolution (HR), high sensitivity (HS), and ultrahigh sensitivity (UHS). In practice, either UHR or HR is set to the detector together with either HS or UHS. After testing 4 kinds of combinations, we found that the combination of UHR-HS gave us far better images than those obtained with the conventional medium energy parallel hole collimator and was best suited for 123I-IMP SPECT imaging of the brain at present. We are now thinking of fusing these two units together into one collimator.

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.

Clinical evaluation of single photon emission computed tomography of the brain

Single photon emission computed tomography (ECT) was performed on 67 patients. ECT images were taken with a Shimadzu scintillation camera, LFOV-E, before a delayed scan.Eighteen of 67 patients showed abnormal findings on the ECT images. Fourteen of the 18 had a transmission X-ray CT (TCT) study as well. There were eleven cases with brain metastases, one case each of an old infarction, a skull metastasis, and a surgical wound. Eleven of fortynine ECT-negative patients had a TCT study as well, and intracranial lesions were found in five. The smallest lesion found by ECT was 0.5 cm in diameter on the TCT image and the largest lesion missed by ECT was a tumor in the corpus callosum, measuring 4.2×2.7 cm.As far as the patients who also received TCT study are concerned, both the ECT and the ordinary scan were thought to be equal in sixteen patients and ECT to be superior in seven whereas the ordinary scintigram was superior in two. At present, ECT is considered to be useful when it is used in addition to the ordinary scans.In the field of clinical nuclear medicine, the development of new radiopharmaceuticals which are labeled with single photon emitters and which can show the metabolic activity of the brain is eagerly awaited.

[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 patients room is small. Additional water may be also meaningful to avoid unnecessary irradiation to the gastric wall.