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Biomedical subjects

Y Korogi

Publications and source records attributed to Y Korogi.

At least 91 records · Page 5Linked to original sources
PubMed1995

Differential diagnosis of extra-axial intracranial tumours by dynamic spin-echo MRI.

Dynamic MRI was performed on 22 patients with extra-axial intracranial tumours. Serial images were obtained every 30 s for 3 min using a spin-echo sequence (TR 200, TE 15 ms) after rapid injection of Gd-DTPA, 0.1 mmol/kg body weight. The contrast medium enhancement ratio (CER) was correlated with the histology of the tumours. Meningiomas and extra-axial metastases showed a sharp rise, then a gradual decline. Although both had a definite early peak of CER, metastases showed a more rapid decline. Neuromas and extra-axial lymphoma showed a slow, steady increase with no peak within 180 s. This study indicates that the CER is helpful in the differentiation of extra-axial tumours.

Adult↗
PubMed1995

Current concepts of imaging in patients with pituitary/hypothalamic dysfunction.

MRI has value in differentiating the normal anatomy and abnormalities of the hypothalamic and pituitary regions. The hypothalamus and the pituitary gland are contiguous structures. They are functionally and physiologically inseparable. The hypothalamus functions primarily as an integrating mechanism for various autonomic and neuroendocrine activities, including temperature regulation, water balance, behavior, and appetite. The adenohypophysis of the pituitary gland contains at least five histologically distinct cell types responsible for hormonal secretion. The characteristic locations of these functional cell types correlate well with the common sites of various pituitary adenomas. MRI can visualize the pituitary gland and the hypothalamus noninvasively in healthy people and in patients with diverse diseases.

Adenoma↗
PubMed1995

Hemifacial spasm: three-dimensional MR images in the evaluation of neurovascular compression.

PURPOSE: To assess the diagnostic accuracy of three-dimensional (3D) magnetic resonance (MR) images in the preoperative evaluation of hemifacial spasm. MATERIALS AND METHODS: In 27 patients with surgically confirmed hemifacial spasm, the axial source images from 3D time-of-flight MR angiography were evaluated for 27 symptomatic sides and 26 asymptomatic sides by three observers in a blinded manner for neurovascular compression and identification of compressive vessels. RESULTS: Sensitivity was 95% and specificity was 77%. Vascular compression on the symptomatic sides could be identified retrospectively in all 27 patients. On the asymptomatic sides, vascular compression could be excluded retrospectively in all but one patient. In the blinded study, as the mean value of three observers, the vertebral artery and posterior inferior cerebellar artery could be identified correctly in seven and 7.7 of seven and nine patients, respectively, whereas the compressive anterior inferior cerebellar artery was identified correctly in 7.7 of 16 patients. CONCLUSION: Three-dimensional MR images have a high diagnostic accuracy and are useful in the preoperative evaluation of hemifacial spasm.

Adult↗
PubMed1995

Intravascular ultrasound imaging of peripheral arteries as an adjunct to atherectomy: preliminary experience.

12 atherosclerotic lesions in nine patients, including four restenoses after balloon angioplasty, were treated by atherectomy under the guidance of intravascular ultrasound (US). Echogenicities of the plaques and morphological alterations in the arterial walls produced by atherectomy were evaluated. The two-layered appearance of post-angioplasty restenoses was found to be inner fibrous intimal thickening with proliferation of smooth muscle cells and outer residual collagen-rich plaque. The deep cut surfaces were shown as concave U-shaped defects. Medial tissues were present in all cases where intravascular US demonstrated the disruption of a thin hyperechoic layer of the internal elastic lamina. Intravascular US imaging may provide valuable information on the degree, eccentricity and histological type of stenosis, the presence of calcification before atherectomy, and on the extent of excision and the morphological changes in the arterial wall after atherectomy.

Aged↗
PubMed1995

Superselective intraarterial infusion of cisplatin for squamous cell carcinoma of the mouth: preliminary clinical experience.

OBJECTIVE: The purpose of this study was to assess the initial clinical response to superselective intraarterial infusion of cisplatin for treating stage III and stage IV squamous cell carcinoma of the mouth. SUBJECTS AND METHODS: Thirteen patients received intraarterial cisplatin therapy. The tumors were located in the tongue (n = 7), gingiva (n = 3), buccal mucosa (n = 1), hard palate (n = 1), and floor of the mouth (n = 1). A coaxial technique was used to place microcatheters in the lingual, facial, inferior alveolar, buccinator, and distal internal maxillary arteries, depending on tumor location. The feeding vessels were identified by staining the tumor with infusion of indigocarmine dye in the selected vessel. Relatively low-dose cisplatin (30-40 mg/m2) was injected at the rate of 50 mg/hr. Two or three injections were performed, with a 1-week interval between injections. After chemotherapy, eight patients underwent surgery, four had radiation therapy, and one had both. RESULTS: Thirty-four intraarterial infusions were done successfully without any complications. Arterial infusion of indigocarmine dye was useful for exact identification of feeding vessels, especially when the tumor was extensive, at the margin of the arterial supply, or near the midline. The overall response rate was 92% (complete response [tumor completely resolved], 38%; partial response [tumor reduction > or = 50%], 54%). Ten of 13 patients had no recurrence from 4 to 19 months (mean, 10 months) after treatment. Two patients died of metastatic diseases 6 months after surgery or radiation therapy. One patient had local recurrence 8 months after surgery and postoperative irradiation. No systemic toxicity such as renal failure, liver dysfunction, or bone marrow suppression was observed. Mild and transient local toxicity such as edema or mucositis of the infused area was relatively common. Trigeminal neuralgialike symptoms and reduced mouth opening occurred in two cases and one case, respectively, probably due to direct toxicity to the peripheral trigeminal nerve and masticatory muscles, respectively. CONCLUSION: Superselective intraarterial infusion of low-dose cisplatin is feasible and safe and may have important applications in treating advanced carcinoma of the mouth.

Aged↗
PubMed1995

[Complications of percutaneous transluminal angioplasty].

Four hundred twenty-three percutaneous transluminal angioplasties with 383 percutaneous arterial punctures in 346 patients were reviewed to determine the frequency, distribution and causes of complications. Complications were seen at the angioplasty site and puncture site along with miscellaneous complications, the incidence rates being 9.5% (40 of 423 PTAs), 11.7% (45 of 383 punctures), and 2.0% (7 of 346 patients), respectively. Major complications occurred in 20 cases, and surgical procedures were required in six cases. Mortality as a complication of PTA was not seen. Angioplasty site complications included 13 spasms, eight dissections, five thromboses, 13 distal embolizations and one perforation. Most puncture site complications were benign hematomas, but there were other types such as a pseudoaneurysm requiring bypass grafting, a thrombosis requiring thrombolysis and a large quantity of bleeding requiring transfusion. The incidence of angioplasty site complications was significantly higher (p < 0.01) in the procedure for complete occlusion than that for stenosis. The puncture site and miscellaneous complications were also more frequent in complete occlusions. The incidence of complications increased with age, although this tendency did not reach statistical significance.

Adolescent↗
PubMed1995

Skull metastasis from hepatocellular carcinoma. CT, MR and angiographic findings.

CT, MR and angiographic findings of 6 patients with 9 skull metastases from hepatocellular carcinoma (HCC) were reviewed. In 3 of 6 patients, local pain or neurologic deficit was the initial main manifestation of the disease, although all had been treated for chronic liver disease. In the remaining 3 patients, skull metastases were detected following treatment of HCC. The metastatic lesions appeared as expansile osteolytic masses on CT and as hypervascular masses on angiography. All lesions were demonstrated on MR imaging. Compared with the brain parenchyma, the lesions were iso- or hypointense on T1-weighted and T2-weighted MR images. The lesions were moderately to markedly enhanced by Gd-DTPA. Flow voids were shown in the tumors in 5 lesions. HCC should be included in the differential diagnosis of an osteolytic hypervascular lesion of the skull, especially in Oriental patients. The relatively hypointense tumor on T2-weighted MR images associated with flow void, different from primary skull tumors or directly invasive tumors, may support the diagnosis of HCC metastasis.

Aged↗
PubMed1994

[Percutaneous transluminal angioplasty of the ilio-femoro-popliteal arteries: initial and long-term results].

The initial and long-term results of percutaneous transluminal angioplasty (PTA) were assessed in 254 atherosclerotic lesions of the ilio-femoro-popliteal arteries in 130 patients. There were 122 men and 8 women, aged 36-85 years (average, 68 years). Follow-up periods ranged from 1 to 131 months, with a mean of 42 months. PTA was performed in 6 patients in Fontaine's stage I, 112 patients in stage II, and 12 patients in stage III-IV. We reported initial success rates of 92%, 58%, 83% and 74% for iliac stenosis, occlusion, femoro-popliteal stenosis and occlusion, respectively. Overall, the initial success rate was 82% (203/247). The 5-year patency rates according to Kaplan-Meier analysis were 70%, 69% and 63% for iliac stenosis, occlusion and femoro-popliteal stenosis, respectively. In femoro-popliteal occlusion, the 1-year patency rate was 42%, which was significantly worse than that for stenosis (P < 0.01). The longest patency periods obtained were 131 months in the iliac artery, and 106 months in the femoro-popliteal artery. The recurrence rate within 6 months was significantly higher in patients with diabetes. The recurrence rate between 6 and 12 months was significantly higher in patients with poor run-off, and those of advanced age.

Adult↗
PubMed1994

[Transluminal atherectomy for occlusive peripheral vascular disease: preliminary results].

We studied the preliminary results of atherectomy of atherosclerotic lesions involving the lower extremities in 10 patients. Fifteen arterial stenotic lesions, five iliac, eight superficial femoral, one popliteal, and one anterior tibial, were treated. Five lesions were re-stenoses after balloon angioplasty, while the remaining lesions were previously untreated primary stenoses. For atherectomy, over-the-wire atherectomy catheters ranging in size from 7 to 10-F were used. Balloon angioplasty was also performed in cases 3, 6 and 9. Atherectomy was considered a success in all patients based on angiographic and clinical criteria. Complications occurred in three patients: intimal dissection, distal embolism and arterial spasm. In the patients with distal embolism, a surgical approach was required to remove the embolus. The internal elastic lamina or media was resected in 10 lesions on the histopathologic specimens. Although further assessment of complications and long-term results is required, these results suggest that atherectomy is useful for treating occlusive peripheral vascular disease.

Aged↗
PubMed1994

[Percutaneous transluminal angioplasty of the subclavian arteries].

We studied the complications and long-term results of percutaneous transluminal angioplasty (PTA) of subclavian artery stenosis in 11 patients. In all patients but one, the systolic blood pressure before PTA in the arm on the involved side was at least 30 mmHg lower than that in the opposite arm. PTA of 11 left subclavian arteries and one right subclavian artery was attempted. Five of the patients suffered from symptoms of vertebrobasilar insufficiency as well as ischemia of the upper limb, two had only cerebral symptoms, two had only ischemia of the upper limb, and another had no symptoms related subclavian arterial lesion. Standard techniques for PTA were employed, using the femoral route eight times and the axillary route four times. Angioplasty was successful in 11 lesions (92%). In the successfully treated patients, the blood pressure in the ipsilateral arm was significantly increased after PTA. No complications occurred during or after the procedure. The patients were followed for 2-74 months (mean 25.7 months). During this time, no recurrence of the stenosis was observed, although the symptoms of vertebrobasilar insufficiency did not always improve. These results suggest that PTA is useful for treating subclavian artery stenosis.

Adult↗
PubMed1994

Hypertrophic olivary degeneration: MR imaging and pathologic findings.

PURPOSE: To assess magnetic resonance (MR) imaging findings of hypertrophic olivary degeneration (HOD) due to hemorrhage and correlate them with pathologic findings. MATERIALS AND METHODS: MR imaging was performed in 11 patients--eight with pontine tegmental hemorrhages (THs) and three with cerebellar hemorrhages in the dentate nuclei. The interval from hemorrhagic ictus to the MR studies was 3 weeks to 49 months. Pathologic specimens came from a woman who died of brain stem hemorrhage. RESULTS: Involvement of the central tegmental tract produced ipsilateral HOD; that of the dentate nucleus or superior cerebellar peduncle produced contralateral HOD. Bilateral olivary changes occurred only when the TH also involved the superior cerebellar peduncle. In bilateral THs, HOD was limited to the dominant bleeding side because of the lateral position of the central tegmental tract. Hyperintense areas of the oliva appeared 3 weeks after ictus. Hypertrophy appeared after 5-15 months. Microscopically, vacuolar degeneration of neurons and hypertrophy of astrocytes with gliosis were seen. CONCLUSION: MR images may depict very early neuronal changes in the oliva and are well correlated with pathologic staging.

Adult↗
PubMed1994

Intracranial aneurysms: diagnostic accuracy of three-dimensional, Fourier transform, time-of-flight MR angiography.

PURPOSE: To assess the accuracy of three-dimensional, Fourier transform, time-of-flight magnetic resonance (MR) angiography in the identification of intracranial aneurysms. MATERIALS AND METHODS: MR angiograms of 126 patients (59 male and 67 female patients, aged 12-77 years) with various intracranial vascular lesions were evaluated. Seventy-eight aneurysms, including 60 less than 5 mm in diameter, in 61 patients were depicted at conventional angiography. Eight projection images, as well as one axial collapsed MR angiogram obtained with a maximum-intensity projection algorithm, were used for evaluation. RESULTS: Sensitivity for the five observers ranged from 58% to 68% (mean, 63%). Higher sensitivity was achieved for anterior communicating and middle cerebral artery aneurysms, while that for internal carotid artery aneurysms was poor. Sensitivities for small and medium aneurysms ranged from 50% to 60% (mean, 56%) and from 77% to 94% (mean, 86%), respectively. CONCLUSION: MR angiography can depict intracranial aneurysms 5 mm or larger with good accuracy but is less useful for the identification of smaller aneurysms.

Algorithms↗
PubMed1994

Intracranial vascular stenosis and occlusion: diagnostic accuracy of three-dimensional, Fourier transform, time-of-flight MR angiography.

PURPOSE: To assess the accuracy of three-dimensional, Fourier transform, time-of-flight magnetic resonance (MR) angiography in the detection of intracranial steno-occlusive diseases. MATERIALS AND METHODS: One hundred thirty-one patients (62 male and 69 female patients, aged 6-77 years [mean, 53 years 8 months]) underwent MR and conventional angiography for evaluation of possible intracranial vascular disease. A total of 502 arteries were assessed. Eight projections and a collapsed image postprocessed by means of a maximum-intensity projection algorithm were reviewed by five observers in a blinded manner, with conventional angiography as the standard. RESULTS: A total of 32 steno-occlusive lesions were available for review. Receiver operating characteristic analysis from the pooled data revealed overall sensitivities of 85% and 88% and specificities of 96% and 97% for the internal carotid artery and the middle cerebral artery, respectively. CONCLUSION: MR angiography is useful as the primary diagnostic tool for evaluating suspected intracranial steno-occlusive disease.

Algorithms↗
PubMed1994

Visibility of epidermoid tumors on steady-state free precession images.

PURPOSE: To determine whether steady-state free precession sequences improve the MR visibility of epidermoid tumors in comparison with spin-echo images. METHODS: Patients were four women and three men with epidermoid tumors in the subarachnoid spaces. MR was performed with a 1.5-T superconductive unit. For steady-state free precession imaging, three-dimensional Fourier transform fast imaging with steady-state free precession (FISP) images were used (20-40/7 [repetition time/echo time], flip angle of 25 degrees). The visualization and contrast-to-noise ratio were compared in FISP images and spin-echo images. In one case, the images of FISP and fast low-angle shot were obtained with variable repetition times and flip angles to evaluate the best pulse sequences for the visualization of epidermoid tumors. RESULTS: The contrast-to-noise ratios between tumors and cerebrospinal fluid ranged from 7.9 to 17.5 (average was 12.9) on FISP images. The average of contrast-to-noise ratios on T1, T2, and proton density-weighted spin-echo images were 1.6, 2.0, and 4.2, respectively. Three-dimensional Fourier transform FISP images best showed central nervous system and demonstrated epidermoid tumors excellently. CONCLUSIONS: Epidermoid tumors in the subarachnoid spaces were better demonstrated on steady-state free precession (three-dimensional Fourier transform FISP) than on conventional spin-echo images.

Aged↗
PubMed1994

MR findings in seven patients with organic mercury poisoning (Minamata disease).

PURPOSE: To study the long-term MR findings in seven patients with Minamata disease. METHODS: All patients examined were affected after eating daily considerable amounts of the methylmercury-contaminated seafoods from 1955 through 1958 and showed typical neurologic findings. T1- and T2-weighted images were obtained in axial, coronal, and sagittal sections. RESULTS: The visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex were significantly atrophic. The visual cortex was slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus. CONCLUSION: MR demonstrated the lesions, located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

Atrophy↗
PubMed1993

[Intravascular ultrasound imaging as adjunct to vascular interventions: preliminary experience in patients with atherosclerotic disease].

Catheter-based intravascular ultrasound (IVUS) imaging is new, evolving technique in which a high-frequency transducer is attached to the tip of a catheter. In this study, we evaluated the usefulness of catheter-based IVUS in 11 patients with atherosclerotic disease as an adjunct to PTA or atherectomy. A 30-MHz ultrasound catheter was inserted through a 6 F sheath to obtain real-time and cross-sectional images. The IVUS images demonstrated a three-layered appearance of muscular arteries, intimal thickening and calcification. IVUS was performed in 11 patients undergoing percutaneous transluminal angioplasty (7 patients) or atherectomy (4 patients). The presence of dissection between the media and atheroma was observed after balloon angioplasty, while IVUS imaging demonstrated a smooth wall after atherectomy. There was a good correlation between IVUS and angiography in the quantitative assessment of luminal %diameter stenosis before vascular intervention, but a poor correlation was observed after angioplasty, probably due to the dissections from balloon dilatation that resulted in irregular crescentic pathways with unclear borders to the lumen on angiography. The results of our study illustrate the potential utility of IVUS as an adjunct to transluminal vascular intervention.

Aged↗
PubMed1993

Correlation of sequential magnetic resonance imaging of experimental brain ischemia with histologic changes in gerbils.

RATIONAL AND OBJECTIVES: To characterize Gd-DTPA-enhanced T1-weighted images (Gd-T1WI) in the acute phase of cerebral ischemia, sequential magnetic resonance images of 84 Mongolian gerbils with occlusion of the left common carotid artery were evaluated. METHODS: Twelve gerbils were used for each group, among which the occlusion time (5-180 minutes, permanent) varied. Histopathologic changes developing within the first 2 weeks were compared with patterns on T2-weighted images and Gd-T1WI on a 7.05-Tesla system. RESULTS: Although T2-weighted images and Gd-T1WI both demonstrated abnormal findings as early as 3 hours after occlusion, Gd-T1WI demonstrated more definite abnormalities with shorter occlusion than T2-weighted images (especially when there were only mild histologic changes). The earliest changes were an abnormal enhancement around and within the lateral ventricles in temporary occlusions; this was not demonstrated in permanent occlusions. CONCLUSIONS: Magnetic resonance images using Gd-DTPA demonstrated abnormal permeability within 3 hours after occlusion, and the pattern is correlated with intensity of ischemia.

Animals↗