Biomedical subjects
Publications and source records attributed to K Torizuka.
The CT findings in three cases of surgically proven hydrosalpinx following tubal ligation are described. In every case a cystic mass of characteristic tubular shape was detected in the pelvic adnexal region. These findings can be considered diagnostic of iatrogenic hydrosalpinx.
Two cases of pedunculated, cystic uterine leiomyoma with unusual CT manifestations are described. The normal contours of the uterus were largely preserved. Ascites and pleural effusion were noted in one case.
Four patients with cavernous hemangioma of face and neck were evaluated with magnetic resonance imaging. Pathologically, soft tissue cavernous hemangiomas are characterized by small feeding arteries and large blood poolings. Arteriography usually fails to demonstrate the extent of the lesion. Computed tomography does not allow differentiation between these lesions and surrounding normal tissues. Magnetic resonance clearly demonstrates hemangiomas with good contrast between lesion and normal tissues. Spin-echo technique with long echo time appears to be particularly useful to delineate these lesions.
Pituitary glands of 60 normal volunteers (30 men 20-36 years old, and 30 women 18-42 years old) were studied by 1.5 T magnetic resonance (MR) imaging. The T1-weighted images (T1WI) [repetition time (TR) = 400 ms; echo time (TE) = 25 ms] were obtained in the coronal, sagittal, and axial planes. Proton density (PD)/T2-weighted images (PDWI/T2WI) (TR = 2,000 ms; TE = 25/100 ms) were obtained in the sagittal plane using 3 mm slice thickness. On T1WIs of all subjects the posterior part (PP) of the pituitary fossa showed the highest signal, which was indistinguishable from fatty tissue. This study reveals that this region of high signal intensity (PP) corresponds to the posterior lobe and not intrasellar fat because its shape, size, and position are compatible with the posterior lobe; its signal intensity differs from that of fatty tissue on PDWI and T2WI; the absence of an intrinsic chemical shift artifact (CSA) characteristic of fat; and due to CSA, a dorsum with fatty marrow is shifted relative to the PP (or may be made to merge with it). Regarding the differentiation of the two lobes of the pituitary gland on MR, the morphology of the anterior and posterior lobes was evaluated and great variation found. Appreciation of normal is particularly important in evaluating coronal images for small pituitary lesions.
Positron emission tomography with radioactive nitrogen gas as well as CT were performed in seven patients with diffuse panbronchiolitis (DPB) to evaluate regional changes on pulmonary ventilation and lung attenuation values. Special focus of this study was on the difference between the central and peripheral parts of the lung. Mean ventilatory time constants measured in the peripheral parts of the lung were significantly greater than those in the central parts. Moreover, mean CT attenuation values in the peripheral parts were also significantly lower than those in the central parts, indicating that hyperinflation of the lung in DPB was located mainly in the peripheral parts. Such stratified distribution of ventilatory impairment is considered to be characteristic of diffuse bronchiolar narrowing because, in the peripheral parts of the lung, there are no large airways. In addition, different branching patterns of airways between the central and peripheral parts of the lung may play an important role in the mechanism of selective injury of bronchioles in the peripheral parts.
Though unilateral blood distribution of the vertebral artery has not been studied in humans, it is significant when considering the ischemic events especially embolic occlusion in vertebrobasilar system. To clarify the blood distribution, Krypton-81m was continuously infused into the vertebral arteries of 10 patients. Radioactivity was recorded by a rotating gamma camera. The perfusion images, reconstructed by computer in the transaxial plane, were classified according to whether the distribution was equal, or predominantly unilateral. Overlapping of blood supply from each vertebral artery was studied. In addition, the perfusion from one of the vertebral arteries revealed four distribution patterns with respect to laterality. A) ipsilateral; B) contralateral; C) bilateral; D) mosaic. Images obtained following perfusion of the vertebral artery show less uniformity compared to that of the internal carotid artery, suggesting a complicated vascular supply of the vertebral basilar territory. This complex distribution can be classified by the use of continuous infusion of Krypton-81m.
In order to evaluate the usefulness of computed tomography (CT) and 131I meta-iodobenzylguanidine (131I-MIBG) scintigraphy for the localization of pheochromocytoma, a prospective study was undertaken in 23 patients with possible pheochromocytoma. Seventeen tumors were identified in 13 patients. Two tumors were extra-adrenal. CT was superior for locating tumors in the adrenal glands while 131I-MIBG scintigraphy was more useful in the detection of extra-adrenal pheochromocytoma. Together with adrenal and extra-adrenal pheochromocytoma, the sensitivity for locating the tumor was calculated as 82 per cent (14/17) for CT and 76 per cent (13/17) for 131I-MIBG scintigraphy, respectively. One adrenal tumor (1 cm in size) only was missed by both methods. No false positive CT scans of 131I-MIBG scintigraphy were obtained in the remaining 10 patients who had possible pheochromocytoma but were excluded. These results indicated that CT and 131I-MIBG scintigraphy were both useful tools for detecting pheochromocytoma.
A patient with an Edmondson type I-II hepatocellular carcinoma had, at celiac angiography, a poor arterial supply but a rich portal supply as observed at percutaneous transhepatic portography, an observation not previously reported in this disease. The importance of demonstrating the vascular supply of the tumor previous to planned intravascular treatment is obvious.
We present the MRI findings of six patients with angiographically documented moyamoya disease. All patients underwent CT and MRI, and MRI findings were compared with those of CT. In two patients both preoperative and postoperative MRI were performed. Most of the abnormalities secondary to moyamoya disease were clearly identified on MRI, which proved to be superior to CT, and it was revealed that the effectiveness of surgery as well as the severity of the disease could also be evaluated successfully by this powerful technique.
In the current study, two cases of hepatoma are reported in which N-isopropyl-(I-123)-p-iodoamphetamine (IMP) liver scan demonstrated increased accumulation in the tumor corresponding to the areas enhanced on contrast enhanced CT (CE-CT). In contrast, there was no IMP accumulation in the necrotic area of the tumor in which no enhancement was found on CE-CT. Thus, IMP liver scan seems to have the potential to assess the viability of a hepatoma as well as to detect and localize it.
To compare the contrast enhancement of Gd-DTPA with the uptake of 99mTc-DTPA, a study was carried out in two steps. In the first step, images comparable in terms of data acquisition time and thickness were obtained after computer processing, and processed images of 99mTc-DTPA and Gd-DTPA enhanced MRI were compared from the morphological aspect. In the second step, the arterial blood concentration of Gd-DTPA and the effect of T2 shortening on signal intensity were studied. It was concluded that Gd-DTPA enhanced MRI can provide functional information analogous to that obtained from radionuclide studies, possibly enabling semiquantitative analysis of contrast enhancement to be performed.
The purpose of this study was the clinical application of 67Ga-DFO-DAS-fibrinogen 67Ga-fibrinogen in normal volunteers and patients with arterial or venous therombus, or bypass graft. DFO-DAS-fibrinogen was available as a lyophilized product and easily labeled by simple mixing with 67Ga-fibrinogen solution (2 mCi/2 ml). Images were taken by a scintillation camera 72 hours after the venous injection of 67Ga-fibrinogen (2 mCi). Ga-67 fibrinogen accumulated well in the liver and kidney in normal volunteers at the early stage, and radioactivity in the kidney, lung, and heart decreased after noticeably after 48 hours postinjection. Ga-67 fibrinogen clearly visualized fresh and old arterial thrombi localized in the thorax or abdomen of all patients suffering aneurysm, and in occlusive bypass graft, contrary to past observations with labeled fibrinogen. In venous thrombus, with the pulmonary artery included, visualization was limited to fresh thrombi of up to one month old. No adverse side effects were observed in any case.
The clinical usefulness of 67Ga-DFO-DAS-fibrinogen, a newly developed thrombus imaging agent, was evaluated. Fifteen cases were given 2 mCi of 67Ga-DFO-DAS-fibrinogen and images were obtained up to 96 hours after injection. Abnormal accumulation of 67Ga-DFO-DAS-fibrinogen was imaged in seven cases with either venous or arterial thrombi, and no side effects were noted. These results suggested that 67Ga-DFO-DAS-fibrinogen might be a promising agent for thrombus imaging.
It is well known that patients with pseudo (PHP)- and idiopathic (IHP) hypoparathyroidism are frequently associated with intracranial calcifications. The relative sensitivity of computed tomography (CT) and conventional skull radiography in detecting basal ganglia calcifications was studied in two patients with PHP and six with IHP. CT was more sensitive: the detection rate was 71% (5/7) for CT and 14% (1/7) for skull radiography. Furthermore, patients with more prolonged hypocalcemia showed a higher incidence of calcifications. Thus, CT was useful as a diagnostic technique in the early detection of calcified basal ganglia.
The posterior aspect of the normal sellar content usually displays high intensity signal on T1-weighted images. The shape, size, and location of this high intensity seem to be compatible with the posterior lobe of the pituitary gland. But fatty tissues such as intrasellar fat pad or fatty marrow of the dorsum sellae or both must be excluded as other possible sources of this high intensity signal. Two sellar phantoms were prepared. Both included high intensity posterior parts, one due to high concentration of a paramagnetic ion and the other due to fat. Magnetic resonance imaging of these phantoms showed that the fatty component was accompanied by distinct chemical shift artifacts in a predictable way. The absence of chemical shift artifact in the sellar content of normal volunteers excluded the fatty tissue as representing the high intensity posterior part. The high intensity posterior part of the normal sellar content appears to represent the posterior lobe of the pituitary gland.
A false aneurysm of the left ventricle is an uncommon and usually fatal condition, although sometimes it may be successfully repaired with surgery. This report describes two cases of false left ventricular aneurysms detected by first-pass radionuclide ventriculography. The aneurysmal chamber with a small neck giving a characteristic hourglass configuration to the ventricle was clearly demonstrated in these cases. Contrast ventriculography showed similar findings. Cross-sectional echocardiography revealed the characteristics of the false aneurysm in the second case, but was unsuccessful in the first due to pulmonary emphysema. The first patient unfortunately died of a rupture of the false aneurysm but the second patient was treated successfully with surgery. Because of the marked tendency of false aneurysms to rupture, early and safe diagnosis is desirable. Therefore, when a patient shows signs of a left ventricular aneurysm, radionuclide angiography is recommended to differentiate false and true aneurysms non-invasively.
Two cases of isolated chylopericardium, one idiopathic and the other secondary to the lymphangioma of the pericardium are reported here. In both cases, correct diagnosis was made by radionuclide imaging techniques. When imaging the cardiac pool using 99mTc-in vivo, labeled RBC, a large separation between the heart and surrounding organs was demonstrated; this suggested a presence of massive pericardial effusion. On pericardial imaging taken 24 hours after oral administration of 131I-triolein, a donut-like shape was clearly produced, situated in a gap between the separation, suggesting chylous effusion within the pericardial space. On operating, isolated chylopericardium was confirmed in both cases. To our knowledge, this is the first report of preoperative noninvasive diagnosis of chylopericardium in Japan.
Real-time sonographic imaging can clearly represent the biliary ascarid as a longitudinal double linear echo. We call this representation an intraductal tubular image. Such imaging allows easy differentiation of the biliary parasite from calcification and other foreign bodies in the biliary tracts.