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T Kozuka

Publications and source records attributed to T Kozuka.

At least 469 records · Page 26Linked to original sources
PubMedDate not supplied

Acute and subacute non-infectious lung diseases: usefulness of HRCT for evaluation of activity especially in follow-up.

PURPOSE: The purpose of this study was to survey the usefulness of high-resolution CT (HRCT) for the evaluation of activity in acute and subacute non-infectious diffuse infiltrative lung diseases before and after corticosteroid treatment. PATIENTS AND METHODS: Sequential HRCT images and chest radiographs obtained before and after treatment were retrospectively evaluated in 33 patients with acute or subacute noninfectious diffuse infiltrative lung diseases. All these patients were histologically confirmed to have pulmonary Inflammation and to have responded to treatment with corticosteroid. Radiographic and CT scores were correlated with the degree of dyspnea and the results of arterial blood gas analysis using Spearman's rank-correlation coefficient. RESULTS: On follow-up HRCT, the profusion score of areas with increased attenuation was significantly correlated with arterial oxygen tension (PaO2) (p=.003, r=-.53) and the alveolar-arterial oxygen tension difference (AaDO2) (p=.001, r=.57). No other correlation was found after treatment. Nodular and linear opacities were more commonly seen on follow-up chest radiographs and HRCT images than on initial ones. CONCLUSION: HRCT is useful for the evaluation of disease activity in acute and subacute noninfectious infiltrative lung diseases before and after treatment if paying special attention to the profusion of ground-glass attenuation. Even if pretreatment HRCT has not been performed, posttreatment HRCT should be examined.

Acute Disease↗
PubMedDate not supplied

Pitfalls in the interpretation of multidetector-row helical CT images at window width and level setting for lung parenchyma.

This article describes pitfalls in the interpretation of multidetector-row helical CT (MDCT) images at the window width and level settings for lung parenchyma. On MDCT, linear artifacts, which look like black and white linear densities and are called "hurricane artifacts," radiate out from objects that have very different densities from their neighbors. For the evaluation of fine parenchymal details, a low table speed/slice collimation should be used. In fact, axial (step and shoot) scanning may be more effective for the evaluation of fine details. Since artifacts from vessels highly enhanced by contrast medium cause data blackout in the surrounding areas at high table speed/slice collimation, pulmonary parenchyma in such situations should be evaluated with unenhanced CT. Although multidetector-row helical CT is a promising tool for the evaluation of lung parenchyma, it is important to identify its shortcomings due to artifacts when interpreting images at the window width and level settings for lung parenchyma and to apply the appropriate methods for eliminating such artifacts.

Artifacts↗
PubMedDate not supplied

Evaluation of image quality and spatial resolution of low-dose high-pitch multidetector-row helical high-resolution CT in 11 autopsy lungs and a wire phantom.

PURPOSE: The aim of this study was to evaluate whether low-dose high-pitch (6:1) multidetector-row helical high-resolution CT is appropriate for the evaluation of various pulmonary abnormalities, including faint opacities. METHODS: Eleven autopsy lungs were scanned with a multidetector-row CT scanner using 2.5 mm x 4 beam collimation, effective slice thickness 3 mm, 6:1 pitch, 0.8 second gantry rotation speed, 20 cm Display FOV, high spatial frequency (bone) algorithm, and various radiation doses (120 kVp; 160, 80, 40, 24, and 8 mAs). The image quality of each CT set was assessed as adequate or inadequate for diagnosis by two independent observers. In addition, a wire phantom was scanned with the same parameters in order to describe the MTF curves. RESULTS: There was excellent agreement between the observers for the evaluation of image quality (kappa statistic, 0.84). The ratio of images evaluated as inadequate for 8 mAs and 24 mAs was significantly higher than that for 160, 80, and 40 mAs (p<0.01: chi-square test). MTF curves of both 8 and 24 mAs were significantly inferior to those of 40, 80, and 160 mAs (p<0.0 1, Friedman test), while the MTF curve of 40 mAs was relatively inferior to that of 160 mAs (p<0.05, Friedman test). CONCLUSION: More than 40 mAs in combination with 120 kVp is preferable for the evaluation of details of lung parenchyma by high-pitch. multidetector-row helical high-resolution CT.

Autopsy↗
PubMedDate not supplied

Dynamic MR studies of hepatocellular carcinoma with portal vein tumor thrombosis.

Gd-DTPA enhanced dynamic MR studies were evaluated in six patients with hepatocellular carcinoma associated with portal vein tumor thrombus. The portal vein tumor thrombus was clearly visualized as a low intensity lesion. The hepatic segment supplied by the portal vein showed high intensity, probably due to decreased portal blood flow and compensatory arterial blood flow. Tumors located in this segment were shown as areas of relatively low intensity compared with segmental high intensity areas. Thus dynamic MR study was found to be a useful method for differentiating the tumor from the surrounding nontumorous tissue with decreased portal blood flow.

Adult↗
PubMedDate not supplied

Magnetic susceptibility artifact in spin-echo MR imaging of the pituitary gland.

PURPOSE: To evaluate the magnetic susceptibility effect on spin-echo MR images of the pituitary gland. METHODS: Air-in-water phantom experiments and studies in normal volunteers were performed using various sampling bandwidth (8.3-33.3 kHz) spin-echo sequences with the polarity of the readout gradient normal or reversed. RESULTS: Attachment of a sphenoid septum to the sellar floor was the major factor in the appearance of the inferior surface of the pituitary gland. Patterns of distortion and/or artifactual signal intensities, related to the presence or absence of the attachment, were accentuated on the images with narrower bandwidth. A "spearhead shape" deformity of the sphenoid sinus was observed both in the air-in-water phantom experiment, and when no sphenoid septum was present. When a sphenoid septum was present, two spearhead shapes side by side were present. High-intensity artifacts were seen where the sellar floor was misplaced into the pituitary gland. CONCLUSION: Knowledge of the patterns of distortion and high-intensity artifact is important in the diagnosis of pituitary lesions.

Adult↗
PubMedDate not supplied

Pancreatic angiography using balloon catheter occlusion and a vasoconstrictor.

When a vasoconstrictor (noradrenaline) was injected during occlusion of the common hepatic artery with a balloon catheter, the vasoconstrictor flowed only into the proper hepatic artery and constricted it. The balloon was immediately deflated and contrast medium injected into the common hepatic artery. The flow of the contrast medium into the gastroduodenal artery was then increased, clearly visualizing the entire pancreatic-duodenal arcade.

Angiography↗
PubMedDate not supplied

Asymmetric appearance of intracranial vessels on routine spin-echo MR images: a pulse sequence-dependent phenomenon.

PURPOSE: To determine the cause of right to left signal intensity differences arising from intracranial vessels during routine spin-echo axial MR imaging of the head. METHODS AND RESULTS: Using a normal imaging sequence in which the default directions of the frequency and phase axes were horizontal and vertical, respectively, differences in signal intensity arising from the vertebral arteries were observed in a healthy subject. With the exchange of the frequency and phase axes relative to the normal sequence, no signal intensity differences between the vertebral arteries were recognized. Other pulse sequence modifications, ie, the use of motion-compensating gradients and the reversed polarity of the frequency-encoding gradient, also resulted in variable appearances of the vertebral arteries, indicating that the right-to-left signal asymmetry of the vertebral arteries observed on the normal spin-echo image results from a pulse sequence dependent phenomenon. CONCLUSIONS: Frequency-encoding and slice-selection gradients both produce motion-induced phase shifts. These phase shifts depend on the angle between the direction of flow and that of the effective vector sum of these gradients. The asymmetric appearance of the vertebral arteries during normal spin-echo imaging was found to result from the angle dependence of motion-induced phase shifts. Awareness of this artifactual phenomenon is important to avoid confusing it with conditions such as stenosis/occlusion, dissection, or slow flow.

Artifacts↗
PubMedDate not supplied

Neuromas and meningiomas: evaluation of early enhancement with dynamic MR imaging.

PURPOSE: To investigate the role of dynamic MR imaging in the differentiation of neuromas and meningiomas. METHODS: Eleven patients with neuromas and 15 patients with meningiomas underwent dynamic contrast-enhanced MR imaging using a short TE FLASH sequence and a bolus injection of Gd-DTPA. RESULTS: There was no significant difference between these tumors in the signal-enhancement increment at the late phase, which corresponds to the signal-enhancement increment between pre- and postcontrast images in conventional spin-echo imaging. However, the signal enhancement at the vascular phase, ie, the phase where the first passage of Gd-DTPA was recognized both in the arteries and veins, was approximately four times as high in meningiomas as in neuromas. The difference was statistically significant. Furthermore, meningiomas had a wider range of early signal enhancement than did neuromas, reflecting the histologic varieties: two angioblastic meningiomas had the highest values, and three fibroblastic the lowest values comparable with those of neuromas, while meningiomas with other subtypes had intermediate values. CONCLUSIONS: The results of this study indicate that the evaluation of early enhancement with dynamic MR imaging is helpful in the differentiation of neuromas and meningiomas, and possibly in the crude prediction of pathologic subtypes of meningiomas.

Contrast Media↗
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Diffusion imaging of the human brain: a new pulse sequence application for a 1.5-T standard MR system.

We developed a new pulse sequence and investigated whether the anisotropic diffusion in the human brain can be detailed with a standard whole-body MR imager. Apparent diffusion coefficient maps were produced by the proposed sequence using a 1.5-T MR unit. The sequence employed simultaneous application of three orthogonal gradients to achieve an optimal signal attenuation for imaging the brain without any increase in echo time. The orientation of the effective diffusion-encoding gradient was off-axis. On the in vivo apparent diffusion coefficient maps of four healthy volunteers, white matter tracts (the internal capsule and the corpus callosum) and the cortical and deep white matter showed anisotropic diffusion. In the gray matter, such as basal ganglia and thalami, anisotropic diffusion was not observed. A typical whole-body imager can provide in vivo human brain diffusion images of clinical quality. This technique has promising implications for the evaluation of brain development and the diagnosis of degenerative diseases.

Adult↗
PubMedDate not supplied

CT evaluation of anaplastic thyroid carcinoma.

CT findings in 19 patients with anaplastic thyroid carcinoma were compared retrospectively with pathologic findings and the results of palpation. The carcinoma appeared as a large mass of low attenuation accompanied by dense calcification in 58% of the patients; there was necrosis in 74%. Often, adjacent structures were infiltrated. CT correctly showed tumor invasion of the carotid artery (7/7), internal jugular vein (9/10), larynx (5/6), trachea (8/10), esophagus (4/5), mediastinum (5/5), and regional lymph nodes (14/16). Seven patients (50%) had necrotic nodes. CT was superior to palpation in the detection of a primary tumor in one patient and of metastatic nodes in seven patients. It suggested a suitable place for biopsy in two patients, leading to a correct diagnosis. CT altered surgical planning in five patients with intrathoracic extension of the thyroid tumor, and in three patients with laryngeal or esophageal invasion of the tumor. CT can increase diagnostic accuracy in patients with anaplastic thyroid carcinoma by suggesting a likely diagnosis and by indicating an appropriate site for biopsy. It is indispensable in the planning of surgery for patients with this disorder.

Adult↗
PubMedDate not supplied

Tongue cancer: correlation of MR imaging and sonography with pathology.

Ten patients with tongue cancer underwent both MR imaging and sonography. In seven of these patients, pathologic findings from glossectomies were correlated with MR and sonographic results. MR images of resected specimens also were obtained in two patients, and relaxation time was calculated in one of these patients. MR images (5- to 7-mm thick slices) were obtained by using a 0.1-T resistive magnet with a 128 x 256 acquisition matrix. MR and sonography had almost the same sensitivity for detecting primary-site tongue cancer. However, in the three patients with extraorgan spread of tumor, MR was superior, showing three of three cases, compared with sonography, which showed extraorgan spread in only one of the three cases. Although MR failed in one patient to differentiate postradiation scar tissue from tumor, because of similar relaxation time of both, this imaging technique proved to be an important adjunct to the physical examination in the staging of tongue cancer.

Adult↗
PubMedDate not supplied

Computed tomography and ultrasonography in parotid tumors.

To determine the most appropriate radiographic approach to parotid tumors, computed tomography (CT) was performed in 65 patients with 33 benign tumors, 19 malignant tumors, 3 abscesses and 10 other lesions with a clinical appearance of tumor. In 22 of the 65 cases CT-sialography and in 26 ultrasonography (US) were also performed. The mass was well recognized on CT without sialography in all patients, and the lesion was also well evaluated in all those examined with US. At CT-sialography the tumor was well shown, but this method made it difficult to differentiate a benign from a malignant lesion, because the character of the delineation and the border of the tumor were difficult to evaluate. It is concluded that US and CT without sialography are satisfactory for evaluating the parotid tumor, and the indication for CT-sialography is limited to those cases in which the tumor is demonstrated on US, but is unclear on conventional CT.

Adenoma, Pleomorphic↗
PubMedDate not supplied

Computed tomography reveals atypical localization of benign mediastinal tumors.

Computed tomographic appearances of 147 surgically proven mediastinal tumors (113 benign and 34 malignant lesions) were evaluated paying special attention to their localization or extension. Ten of the 113 benign lesions (9%) showed atypical or unique localization or extension, and were divided into three groups. In the first group, two lymphangiomas and one bronchogenic cyst spread over both the precardiovascular and the retrocardiovascular compartments, mimicking a malignant lesion. In the second group, the single cases of thymic hypertrophy, thymic cyst, schwannoma, and pericardial cyst were located atypically in the retrocardiovascular compartment. In the last group, two esophageal leiomyomas and one esophageal duplication showed upward and downward longitudinal extension beyond the azygos arch and the aortic arch.

Adult↗
PubMedDate not supplied

Spontaneous pneumothorax caused by metastatic hemangioendothelioma. Radiographic appearance and pathologic correlation.

A patient with hemangioendothelioma is described, who developed a metastatic pulmonary nodule, subsequently a bullous lesion contiguous to the nodule, and finally spontaneous pneumothorax. In such cases, newly formed bullous lesions may conceal originally visible metastatic foci and can be a potential source of spontaneous pneumothorax.

Hemangioendothelioma↗
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Computed tomography following endoscopic sclerotherapy of esophageal varices.

Computed tomography of the chest following endoscopic injection sclerotherapy for esophageal varices was performed in 17 procedures in 13 patients. CT scans were obtained before and within 48 hours after the procedure. CT findings included: esophageal wall thickening; a low-attenuating lesion within the wall of the esophagus with varying appearances, either laminated, localized, or inhomogeneous; a mediastinal lesion; pleural effusion; and various types of pulmonary changes such as atelectasis, pleural-based lesions, dilatation of peripheral pulmonary vessels, and nodular lesions. However, on follow-up CT they had regressed or disappeared. The changes in the mediastinum and pleural space might be caused by direct extension of inflammation from the esophagus, but those in the lungs, especially dilatation of peripheral vessels, may be caused by the sclerosing agent passing to the pulmonary vessels.

Adult↗
PubMedDate not supplied

Cerebral hemodynamics in arteriovenous malformations: evaluation by single-photon emission CT.

Cerebral hemodynamics in six patients with supratentorial arteriovenous malformations (AVMs) were studied by using single-photon emission CT with three types of radioactive isotopes: N-isopropyl-p-[123I] iodoamphetamine, 81mKr, and 99mTc-RBC in order to determine the local cerebral blood flow and blood volume associated with these malformations. The AVMs were shown to have high flow while other areas of the brain, including the contralateral hemisphere, had variable areas of diminished perfusion. There was increased blood volume in the regions of AVMs, and poor but evenly distributed blood volume in the other regions. CO2 reactivity during hypocapnia was preserved throughout the brain except for the region of the AVMs. In large AVMs, the ischemic state surrounding the nidus was considered to be caused mainly by the cerebral steal phenomenon.

Adult↗
PubMedDate not supplied

Lymphangioma of the mesentery and small intestine: a case report showing a solid tumor with a cystic component on US and CT.

We encountered a patient with multiple lymphangiomas of the mesentery and small intestine. Ultrasonography and computed tomography showed a mesenteric tumor composed of a solid component with a small cystic part. This unusual appearance made the differential diagnosis between lymphangioma and other intra-abdominal solid tumors difficult.

Diagnosis, Differential↗