Search PubMed⌕ Search

Biomedical subjects

Y Itai

Publications and source records attributed to Y Itai.

At least 91 records · Page 5Linked to original sources
PubMed1998

Radioresponse of thymomas verified with histologic response.

Patterns of radiologic response of 10 thymomas treated by preoperative radiotherapy (RT) (18-20 Gy/2 weeks) were determined in conjunction with histologic response. Changes in tumor volume were evaluated with CT scans obtained 5 to 36 days before and 14 to 24 days after the initiation of RT and before surgery. The extent of tumor volume reduction (TR) varied widely (40-78%), while the mean daily volume decrement expressed as a percentage of the pre-RT tumor volume correlated significantly with the pre-RT tumor volume. Histologically, the tumors, all of which were resected 17 to 33 days after RT initiation, generally consisted of predominant fibrous tissues, rare necrotic foci, and few epithelial cells. The TR did not correlate with pre-RT tumor volume, observation period, histologic subtype, or quantity of remaining epithelial cells. The TR of thymomas does not predict RT impact on tumor cells but does reflect the quantity of inherent tumor stroma.

Adult↗
PubMed1998

Extrahepatic arterial supply to the liver: observation with a unified CT and angiography system during temporary balloon occlusion of the proper hepatic artery.

PURPOSE: To evaluate routes of potential extrahepatic arterial supply to the liver. MATERIALS AND METHODS: Twenty-three patients with liver tumors underwent computed tomographic (CT) arteriography of extrahepatic arteries before and after temporary balloon occlusion of the proper hepatic artery. The right inferior phrenic artery (RIPA), left inferior phrenic artery (LIPA), superior mesenteric artery (SMA), celiac axis, and left gastric artery (LGA) were evaluated. RESULTS: During temporary balloon occlusion of the proper hepatic artery, extrahepatic arterial supply was immediately evident in 22 of 23 patients (96%). The liver was supplied by the RIPA in 17 of 20 patients (85%), by the LIPA in five of six (83%), by the SMA in eight of 16 (50%), by the celiac axis in two of 10 (20%), and by the LGA in one of six (17%). There was no apparent relationship between the enhanced zones supplied by extrahepatic arteries and the presence or absence of nearby tumors. CONCLUSION: Extrahepatic arterial supply to the liver was readily evident in a large proportion of patients during temporary balloon occlusion of the proper hepatic artery. This finding suggests a need for consideration of extrahepatic arterial supply when angiographic intervention for liver tumors is contemplated.

Aged↗
PubMed1998

Relationship between normalization of negative T waves on exercise ECG and residual myocardial viability in patients with previous myocardial infarction and no post-infarction angina.

The usefulness of normalization of negative T waves in exercise ECG was investigated as an index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise test. A total of 39 patients, 20 with T-wave normalization (POS group) and 19 without T-wave normalization (NEG group) on exercise ECG. were studied. Myocardial viability was evaluated by thallium-201 single-photon emission computed tomography (SPECT) during exercise or at rest. We also assessed left ventricular ejection fraction (LVEF) by contrast ventriculography before (n=39) and after percutaneous transluminal coronary angioplasty (PTCA) (n=17). SPECT detected myocardial viability in 16 (80%) of the 20 patients in the POS group and in 4 (21%) of the 19 patients in the NEG group (p<0.01). LVEF increased after successful PTCA in the POS group (from 53+/-13% to 63+/-8%, p<0.025), but fell in the NEG group (from 57+/-10% to 51+/-8%). It is concluded that normalization of negative T waves on exercise ECG is a useful, simple index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise testing.

Adult↗
PubMed1998

Ductectatic mucinous cystic neoplasms of the pancreas: evaluation with MR cholangiopancreatography.

OBJECTIVE: We performed this study to describe the advantages of MR cholangiopancreatography and its findings in revealing ductectatic mucinous cystic neoplasms of the pancreas. CONCLUSION: MR cholangiopancreatography using both projection and source images can reveal characteristic findings of a ductectatic mucinous cystic lesion of the pancreas and show the presence of the communicating duct between the cystic lesion and the main pancreatic duct.

Aged↗
PubMed1998

Transcatheter embolization of celiac artery pseudoaneurysm following pancreatico-duodenectomy for pancreatic cancer. A case report.

A case of transcatheter embolization of a celiac artery pseudoaneurysm in a 70-year-old man is reported. The pseudoaneurysm was considered to be the result of pancreatic anastomotic leakage and an intra-abdominal abscess following pancreaticoduodenectomy with irradiation of 66 Gy for pancreatic carcinoma. To avoid recanalization of the pseudoaneurysm due to retrograde blood flow, first all branches of the celiac artery were embolized with metallic coils, and then the celiac trunk was also occluded. Hepatic arterial flow was preserved by the right hepatic artery arising from the superior mesenteric artery. After the procedure, the patient had no noticeable complications associated with the embolization nor any recurrence of the pancreatic cancer, and he achieved a 2-year survival.

Aged↗
PubMed1998

Development of multispectral autoradiography with solid state detector.

Autoradiography is a useful imaging technique to understand biological function by using radio isotopes (RIs). However, conventional autoradiography using X-ray film or Imaging Plate can not easily image distributions of different RIs simultaneously. Each tracers describes each biological functions, therefore we constructed here a multispectral autoradiography. The system consists of a solid state detector (SSD) with high energy-resolution to acquire multispectral information, a collimator with small aperture to restrict the region of observing area, and a translational stage to scan the specimen. The distribution of the RI of interest agent can be obtained by mapping spectrum intensity within the energy-window to corresponding observed points. We confirmed the validity of this method by experiments with physical phantoms and tissues of rat's hearts. First, we imaged the phantom with 201Tl and 99mTc, and could specify the individual RIs. Next, from rectangular paper phantom soaked in 99mTc-labeled tracer, the spatial resolution of experimental system was estimated on about magnitude of x mm2. Finally, the sliced tissue of rat's heart was imaged. Here, we also propose a new imaging method to improve the spatial resolution and reduce data-acquisition time. It is based on reconstruction from projections like X-ray CT.

Animals↗
PubMed1998

[Usefulness of a new technique to assess drug perfusion pattern on balloon occluded arterial infusion therapy (BOAI) for intrapelvic malignant neoplasms: subtraction CT with low-flow-rate arterial injection (S-CTLA)].

The hemodynamics in balloon occluded arterial infusion therapy (BOAI) for intrapelvic malignant neoplasms is not totally understood. A new technique to evaluate the perfusion pattern of anticancer drugs under BOAI, which is named Subtraction CT with Low-flow-rate Arterial injection (S-CTLA), has been developed by us. In this technique, spiral CT data were acquired twice, before and after low-flow-rate (0.2 ml/sec) injection of contrast agent. Then, subtraction images were reconstructed. S-CTLA was performed in 3 patients with urinary bladder cancer. Our results provided demonstrable images as well as useful information in predicting the effectiveness of BOAI.

Aged↗
PubMed1998

[Arterial redistribution of extrahepatic collaterals to the liver under temporary balloon occlusion of the proper hepatic artery].

Three patients with liver metastases receiving transarterial chemotherapy underwent embolization of extrahepatic collaterals to the liver under temporary balloon occlusion of the proper hepatic artery. Enhancement in the liver and tumors was observed at CT arteriography through the right inferior phrenic artery and was accentuated under balloon occlusion in all patients. A Cyanoacrylate-Lipiodol mixture was infused through the right inferior phrenic artery to occlude arterial communications with intrahepatic arteries. Better contrast agent distribution was obtained in all patients after embolization. It is suggested that this procedure can be effective for arterial redistribution against extrahepatic collaterals to the liver.

Antineoplastic Agents↗
PubMed1998

[Medial collateral ligament of the knee and its surroundings: MRI findings of normal and abnormal structures].

Normal and abnormal structures of the medial corner of the knee were evaluated with coronal and axial MR images. MRI revealed 35 medial collateral ligament (MCL) tears and 61 medial meniscus (MM) tears in 200 consecutive examinations. Just under the MCL, little or no fluid retention was identified between the superficial and deep layers of the MCL or between the MM and MCL in normal knees and in cases of MM tears. At the anterior aspect of the MCL, the deep layer merges with the capsule of the suprapatellar bursa, potentially leaving space for fluid retention. Fluid collection posterior to the MCL was demonstrated in a few cases. Fluid retention with edematous swelling just under the MCL was noted in the cases of MCL tears. MM-MCL distances in the cases of normal structure, MM tears and MCL tears were 2.1 mm, 2.7 mm and 4.7 mm, respectively. The deep layer of the MCL, which was enhanced by the presence of joint fluid, was identified in 71% of cases.

Adult↗
PubMed1997

Radiation tolerance of cirrhotic livers in relation to the preserved functional capacity: analysis of patients with hepatocellular carcinoma treated by focused proton beam radiotherapy.

PURPOSE: To determine the preserved functional capacity of the liver as a probable determinant of radiation tolerance in patients with cirrhosis and hepatocellular carcinoma, who underwent proton beam radiotherapy. MATERIALS AND METHODS: We reviewed computed tomographic (CT) scans of 26 patients with cirrhosis and hepatocellular carcinoma during a period of 12-27 months after proton beam radiotherapy. Tumors were treated with focused proton beams with target doses of 140-186 TDF (time, dose, and fractionation). We measured the degree of hypertrophy of the untreated liver volume by measuring the total liver volume and the treated liver volume which was radiologically identified on contrast-enhanced CT scans. The risk of radiation-induced liver failure was estimated using the prediction score (PS) originally used for estimating posthepatectomy liver failure, substituting the planned treated liver volume for the resection liver volume. RESULTS: The degree of hypertrophy ranged from -19% to 51%, and was significantly positively correlated with the ratio of the planned treated liver volume to the functional liver volume. The PS agreed well with observed radiation tolerance in 21 patients, but underestimated the tolerance in 5. This underestimation was diminished when the PS was recalculated using the identified untreated liver volume in lieu of the planned untreated liver volume. CONCLUSION: As in surgical treatment, radiation tolerance of the cirrhotic liver after focused treatment is closely related to the preserved functional capacity of the identified untreated liver volume, which shows compensatory hypertrophy following radiotherapy.

Aged↗
PubMed1997

Comparison between magnetization transfer contrast and fast spin-echo MR imaging of degenerative disease of the cervical spine at 0.3 T.

We compared magnetization transfer contrast (MTC) with gradient recalled echo (GRE) magnetic resonance imaging (MRI) and fast spin-echo (FSE) MRI of the degenerative cervical spine at 0.3 T. Fifty patients with suspected degenerative disease of the cervical spine were prospectively evaluated. Multislice sagittal and axial images of the cervical spine were obtained using MTC GRE sequence [repetition time (TR)/echo time (TE)/flip angle = 750/23/25 degrees] and FSE sequence with peripheral gating (TR/effective TE = 2000-4000/120). Quantitatively, FSE showed higher signal-to-noise ratio and superior disk contrast between normal and degenerative disks, while MTC images showed superior contrast-to-noise ratio for the cerebrospinal fluid (CSF) versus cord and superior CSF homogeneity. In qualitative analysis, similar results were obtained. In conclusion, FSE and MTC GRE sequences are MRI techniques of imaging the cervical spine that have different characteristics and supplement each other in the diagnostic imaging of degenerative disease of the cervical spine.

Adult↗
PubMed1997

Two-dimensional aortographic coronary arteriography with above-K-edge monochromatic synchrotron radiation.

RATIONALE AND OBJECTIVES: The diagnostic potential of two-dimensional aortographic coronary arteriography with synchrotron radiation was examined in dogs. METHODS: The experiment was performed at a wiggler beam line by using a silicon monocrystal, fluorescent plate, and avalanche-type camera. The x-ray energy was adjusted to just above the iodine K-edge to obtain the highest contrast. Quantitative densitometry was used to compare intravenous coronary arteriography with aortographic coronary arteriography. RESULTS: Aortographic coronary arteriography clearly depicted the branches of the coronary arteries such as the left anterior descending coronary artery, circumferential coronary artery, and right coronary artery to sizes of less than 0.2 mm without major overlap of coronary arteries. Intravenous coronary arteriography depicted only the branches of the left anterior descending coronary artery and right coronary artery with poor image quality. The ratio of contrast material dilution was about 2.4 to 3.4 in aortographic procedures, whereas in intravenous procedures it ranged widely from 7.7 to 15.6. CONCLUSION: These preliminary investigations indicate that two-dimensional aortographic coronary arteriography with synchrotron radiation promises to be a minimally invasive and easily repeatable method of clearly imaging the coronary arteries.

Animals↗