[en] The direct comparison of the intensity between images is impossible in MRI because of a lack of the absolute gray scale. We calculated the relative value of the intensity of intracranial tissues against that of CSF in the same image in multiple spin echo MRIs. Then these values were protted against the change of echo time. This ''relative T₂ relaxation pattern'' was examined in normal white matter and various intracranial tumor tissues in this study. Patterns of normal white matters were almost the same, indicating a good reproducibility of this method. On the other hand, tumor tissues showed various kinds of patterns according to the histopathological differences. These results indicate that this method can be used for the quantitative diagnosis of intracranial lesions. (author)

[en] Nine patients with stricture of the cervical artery (group 1), 4 patients with stricture of the intracranial artery (group II), and 9 normal volunteers (control group) underwent digital subtraction angiography. Mode of transit time, mean transit time, and peak time were obtained as parameters for dynamic function from the time-density curve. There were significant differences in these parameters between the group 1 and the control group; however, no significant differences between the group II and the control group were seen. (Namekawa, K.)

[en] This study was undertaken to evaluate ^99mTc-DTPA renography before and after extracorporeal shock wave lithotripsy (ESWL). Twelve patients with renal calculi were examined in this study. In three patients, bilateral kidneys were treated with ESWL. Sequential renal images of the vascular phase, and the functional and excretory phases were taken using a gamma camera (ZLC 7500, Siemens), after intravenous injection of 555 MBq of ^99mTc-DTPA. Renograms were generated using data stored every 10 seconds for a period of 30 minutes by computer (Scintipac-2400, Shimadzu). Some treated kidneys were enlarged and/or showed uniform retention of radioactivity on sequential images, within a week after ESWL. Renogram patterns after ESWL were varied in each patient. The renogram findings after ESWL seemed to be affected by the presence or absence of stone fragments in the urinary tract. (author)

[en] Transcatheter chemo-embolization (TCE) for hepatocellular carcinoma (HCC) and hepati metastasis (META) was performed on 41 patients. The patients were examined by MR both before TCE and after TCE(1 week and 4 - 5 weeks respectively). The change of the tumor signal intensity was divided into 2 types on a T2 weighted image. One, is the increase of the intensity. The other, is decrease of intensity. The former seemed to reflect the intra-tumoral hemorrhage accompanying tumor necrosis, the latter, seemed to reflect the coagulation necrosis. The ring of low and high intensity around the tumor appeared anew in 11 cases, and in 2 cases, it increased in size. These changes which have never been recognized on CT images, were thought to be a granulation tissue around the tumor. (author)

[en] Regional blood flow and Regional metabolic rate of oxygen of 41 brain tumors were measured using Positron Emission Tomography(PET) and Oxgen-15. 1) Blood flow; Meningioma were not uniform. Glioblastoma were almost low, but in a few case involving small high blood flow area. Astrocytoma were low. Oligodendroglioma were high and medium mixed. Metastatic tumor were all low. 2) Oxygen utilization; Any tumor were almost low. We discussed these results with reference to histology and others. (author)

[en] Our Experience of ECG-gated CT was reported. The phantom, cyclically moving, was scanned with and without ECG-gating method. The ED and ES images of the phantom were sufficient enough for the evaluation with more than 3 scan data. Preliminary scans of 16 patients were reviewed and revealed that the images of 13 cases had good quality. (author)

[en] Four kinds of test-charts for contrast resolution were developed, whereby making it possible to compare slight differences of contrast resolution of digital subtraction angiography (DSA) units. These test charts were also very useful in assessing intensifying screens. The following applications of the test charts were suggested: comparison of the performance (contrast resolution) between the DSA units; selection of the suitable conditions and modes of DSA used in clinical practice; evaluation of DSA units for improving image quality; assessment of intensifying screens to be used clinically. (Namekawa, K.)

[en] SPECT with N-isopropyl-I-123-p-iodoamphetamine (IMP) was fundamentally investigated using phantoms and three collimators. Using optimum technical procedures obtained, SPECT was undertaken 30 min after injection of IMP in 23 patients with acute and chronic or old cerebral infarction. Abnormal findings were detected on SPECT in 13 of the 23 patients, and were well coincident with findings of x-ray CT. SPECT was superior to x-ray CT in clear visualization over wider range. Transaxial, coronal and sagittal slices obtained by SPECT permitted stereoscopic visualization of local cerebral blood flow. In one patient, abnormal findings which were not detected on x-ray CT were visualized on SPECT, coinciding well with clinical symptoms. (Namekawa, K.)

[en] A digital mamo-radiography (DMR) system for mass screening was developed, and was used in clinical trials. DMR was also compared with conventional mamography using films (FMR). Resolution of DMR was high, although it was not comparable to FMR. DMR was capable of changing contrasts and gradations more readily than FMR. Exposure dose of DMR was one thirty that of FMR. Clinical trials of DMR showed the following advantages: Minute changes in contrasts are displayed; diagnosis is easy by image processing; the detection of lesions surrounding the thoracic wall is possible; and no skill for imaging is required. (Namekawa, K.)

[en] Sagittal images of the superior mediastinum obtained by a 0.1 T Asahi Mark J NMR imaging unit were compared with reconstructed images obtained by a YMS CT-8600 scanner. NMR imaging was a useful noninvasive technique for visualizing the whole of the aortic blood vessel of the heart, and x-ray CT was superior to NMR imaging in the detailed visualization of blood vessels branched from the aorta. It is recommended to use x-ray CT in studying the appropriate direction of NMR images to see large vessels. (Namekawa, K.)