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Biomedical subjects

K Kichikawa

Publications and source records attributed to K Kichikawa.

At least 19 recordsLinked to original sources
PubMed2002

The transradial approach for selective carotid and vertebral angiography.

PURPOSE: The transradial approach is not so popular in cerebral angiography. The purpose of this study was therefore to present our experience of success rate and safety of this method. MATERIAL AND METHODS: From December 1998 to June 2001, 526 carotid and vertebral angiographies with DSA were performed via the radial artery. A 1.4-mm catheter was used through a 1.4-mm introducer sheath. We evaluated the procedure as successful if sufficient images for diagnosis were obtained of the bilateral carotid arteries and unilateral vertebral artery. Each patient was reassessed for any complications, occurring until the next morning. The length of time needed for an examination was measured in the last 10 cases. RESULTS: In all but 5 cases, the procedures were evaluated as successful (99.0%). Unsuccessful cases manifested severe pain at the radial puncture, angiospasm at the radial artery, loop formation at the radial artery, occlusion at the subclavian artery, and an aberrant right subclavian artery. No severe complications including neurological ones were encountered. Minor complications were noted in 17 cases (3.2%): 4 cases of thrombus at the ulnar artery, 1 angiospasm at the radial artery, and 12 cases of small hematoma at the puncture site. The radial approach took 14 min less in the common carotid study and 3 min 30 s less in the internal carotid study than by the femoral approach. CONCLUSION: The transradial approach enabled selective studies for carotid and vertebral angiography with a high success rate and safety with few complications.

Adolescent↗
PubMed2001

Detection of early venous filling in gliomas on MRI: preliminary study by 2D time-resolved dynamic contrast-enhanced MR angiography with echo-sharing technique.

We evaluated the detection of early venous filling of gliomas by 2D time resolved dynamic contrast enhanced MR digital subtraction angiography (MR-DSA) with echo-sharing technique and compared the results with those of conventional contrast digital subtraction angiography (C-DSA). C-DSA and MR-DSA examinations were performed in eight patients with malignant gliomas and compared with regard to the visualization of early filling veins; time intensity curves of arteries, early filling veins and normal veins were made, and rise time and time to peak were evaluated. MR-DSA visualized 12 out of 17 early filling veins depicted on C-DSA. The failure of five veins to be depicted may be due to the overlapping of other structures, such as other vessels and tumor stain. On time intensity curves, the mean difference in rise time was 0.9 sec between the artery and early filling vein, and the mean difference of time to peak was 1.6 sec. C-DSA has been the modality of choice in demonstrating early venous filling, a useful finding in the differential diagnosis of gliomas. However the high temporal resolution of MR-DSA with echo-sharing technique provides sufficient visualization of early venous filling of gliomas. Additional information for precise differential diagnosis may be obtained by adding MR-DSA to the imaging protocol for gliomas.

Aged↗
PubMed2001

Stent-Graft treatment of dissecting aneurysm in association with aortic intramural hematoma: when should the procedure be performed?

PURPOSE: To report 2 cases of stent-graft implantation for localized dissecting aneurysm during the conservative treatment of aortic intramural hematoma. CASE REPORTS: One patient underwent stent-graft implantation for 2 localized dissecting aneurysms about 23 months after symptom onset. Computed tomography (CT) 1 year after the procedure demonstrated aneurysm shrinkage. In the other patient, a localized dissecting aneurysm was treated about 3 months after symptom onset, even though the intramural hematoma had not resolved. CT scanning 3 months after the procedure demonstrated aneurysm shrinkage, but also revealed poor attachment of the distal stent-graft to the aortic wall due to subsequent resolution of the hematoma. CONCLUSIONS: Endograft implantation for treatment of localized dissecting aneurysm associated with aortic intramural hematoma should probably not be performed before the hematoma has completely resolved.

Aortic Dissection↗
PubMed2000

Enhancement pattern of normal extraocular muscles in dynamic contrast-enhanced MR imaging with fat suppression.

PURPOSE: To evaluate the internal structure of normal extraocular muscles on fat-suppressed dynamic contrast-enhanced MR imaging. MATERIAL AND METHODS: Ten subjects were examined using fat-suppressed dynamic contrast-enhanced MR imaging. We evaluated the enhancement pattern (C-shaped or ring-like) of extraocular muscles and quantified the maximum ratios of enhancement (Rmax) and maximum ratios of signal increase (Vmax). We also quantified Rmax and Vmax in the central and peripheral portions of medial rectus muscles. RESULTS: In the early phase of dynamic contrast-enhanced MR imaging, a C-shaped or ring-like pattern was observed in 100% of inferior rectus, 95% of medial rectus, 55% of superior rectus, 20% of lateral rectus, and 15% of superior oblique muscles. Overall mean Rmax and Vmax values showed statistically significant differences to the temporal muscles. For the peripheral portion of medial rectus muscles, mean Rmax and Vmax values were greater than for the central portion. CONCLUSION: Using fat-suppressed dynamic contrast-enhanced MR imaging, the C-shape or ring-like internal structure of the extraocular muscles could be visualized, and were considered to reflect their structure of orbital and global layers. Potential usefulness of the fat-suppressed dynamic contrast-enhanced MR imaging for detecting pathological status is suggested.

Adipose Tissue↗
PubMed2000

Aortic stent-grafting with transrenal fixation: use of newly designed spiral Z-stent endograft.

PURPOSE: To evaluate the feasibility and efficacy of a newly designed stent-graft placed across the renal arteries for exclusion of abdominal aortic aneurysms (AAAs) with short or tortuous proximal necks. METHODS: Among a group of AAA patients treated with endovascular grafting, 5 had tortuous proximal necks and 13 had necks <20 mm (mean 13 mm). In these 18 cases, a 2- to 3-cm uncovered segment of the stent-graft was placed transrenally using a catheter inserted into the renal artery as a guide for graft margin positioning. A newly designed stent-graft was constructed from a custom-made spiral Z-stent covered with a thin-walled Dacron material; the endografts were deployed through 16-F (aortoaortic model) or 18-F sheaths (bifurcated devices). Renal function was assessed by preoperative and postoperative measurement of urea nitrogen and creatinine. Aneurysm exclusion and renal artery patency were evaluated during follow-up using spiral computed tomography and angiography. RESULTS: The stent-grafts were correctly placed at the intended site in all 18 patients. Renal function was not affected except transiently in 1 patient who developed bilateral renal artery stenoses 24 hours after the procedure; Palmaz stents were deployed in each renal artery to reestablish satisfactory blood flow. Of the 33 renal arteries crossed by the bare stent-graft segment, all were patent over a mean 14-month follow-up (range 7-24), including the patient with Palmaz stents implanted for postprocedural renal stenosis. Complete aneurysm exclusion was maintained in 15 (83%) of 18 patients; proximal leaks persisted in 3 patients, including 2 with severely angled proximal necks. CONCLUSIONS: Transrenal placement of the uncovered leading edge of custom-made spiral Z-stent-based endografts appears feasible and clinically effective in the treatment of AAAs with short or tortuous proximal necks.

Aged↗
PubMed1999

Expandable metallic stent placement for nutcracker phenomenon.

A 40-year-old woman presented with asymptomatic gross hematuria caused by the nutcracker phenomenon. Despite treatment with hemostatic agents and injection of silver nitrate into the renal pelvis, the hematuria had continued, and severe anemia (hematocrit 17%) had developed. We performed expandable metallic stent (EMS) placement across the left renal vein. Although mild hematuria continued, the anemia resolved after this interventional radiotherapy. EMS placement is a minimally invasive therapy for the nutcracker phenomenon.

Adult↗
PubMed1999

Twin-tube endografts for aortic aneurysms: an experimental feasibility study.

PURPOSE: To explore feasibility of twin-tube endografts (TTEGs) for treatment of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: AAAs were created in six dogs by overdilation of Palmaz stents. TTEGs made of seven 9.5-mm-diameter Gianturco Rösch Z (GRZ) stents and covered with PTFE were deployed simultaneously from both femoral arteries through 10-F sheaths to exclude the AAA. Follow-up aortography was performed immediately and at 2, 4, and 8 weeks. Two dogs were killed at 4 weeks and four were killed at 8 weeks. Gross and histologic examinations were performed. RESULTS: AAA creation and TTEG placement were successful in all six dogs. TTEGs completely excluded AAAs in five dogs. Minor temporary perigraft leak was seen in one dog immediately after stent placement. Four dogs had TTEGs patent to termination at 8 weeks. In two dogs with oversized TTEGs, one of the twin endografts occluded at 2 weeks. At autopsy, TTEGs were formed in semicircular shape and histology did not show any significant inflammatory reaction. CONCLUSION: TTEGs show promise for treatment of AAA, with the potential of reducing the introductory sheath size. Further experimental studies, particularly with TTEGs extended into iliac arteries, are warranted.

Angiography↗
PubMed1999

Histologic comparison of coronary and iliac atherectomy tissue from cases of in-stent restenosis.

Pathologically, restenotic lesions after stenting were investigated by use of atherectomized tissues of seven coronary and seven iliac arteries. The mean interval of the stent deployment to restenosis was 9.1 months for the coronary artery and 33.7 months for the iliac artery, indicating a 3.7-fold longer interval for the latter. This study does not include cases of acute thrombotic occlusion. The atherectomized tissue from restenotic coronary arteries showed abundant neointima with alpha-actin-positive and ultrastructually synthetic-type smooth muscle cells in a rich myxomatous extracellular matrix. In the iliac arteries, the predominant component of restenosis consisted of organized thrombi. The neointima of the iliac arteries was mature, and only a small amount of spindle cells were observed in the hyalinized matrix. The tissue that developed restenosis after stenting was different in the coronary and iliac arteries included in this series. This study on the atherectomized tissue suggests that even in the chronic stage, a major cause of in-stent restenosis among the larger caliber vessels such as the iliac artery is not neointima but stent thrombosis.

Aged↗
PubMed1998

Outcomes of stent-graft treatment of false lumen in aortic dissection.

BACKGROUND: Stent-graft treatment for aortic disease promises to lead to a less invasive therapy than conventional surgical therapy. However, this treatment has not been established as a therapy for aortic dissection. The aim of this study was to examine the effect of stent-graft treatment of aortic dissection, as measured by follow-up data on entry site closure, clotting in the false lumen, and the outcome of the false lumen from the acute to chronic phase after operation. METHODS AND RESULTS: We used a stent-graft of our own design to close the entry site of aortic dissection in 21 cases: 9 were acute (< 14 days), 8 subacute (< 6 months), and 4 chronic (> 6 months). Nine were type A and 12 were type B. In 15 cases, the stent-graft was inserted through the transverse arch, which had been surgically opened under median sternotomy. In the other 6 cases, the stent-graft was inserted by means of a transcatheter through a femoral artery. Using computed tomographic scans, we followed and examined clot formation in the false lumen and reduction in size of the false lumen at 3 levels: at the level of maximum aortic diameter, at the distal end of the stent-graft, and 50 mm distal to the stent-graft. The entry sites were successfully closed in 19 cases (90.4%); in the remaining 2 (both treated with a transcatheter) there was perigraft leakage into the false lumen. The hospital mortality rate of these stent-graft treatments was 14.3% (3 of 21). At 2 weeks after operation, the false lumen had completely clotted, respectively, in 100%, 77%, and 38% of cases at the 3 measurement levels. Substantial shrinkage (> 50% in diameter) of the false lumen at 6 months after the operation was observed in 72%, 60%, and 38% of cases at the respective levels. Shrinkage of the false lumen was particularly enhanced in patients treated within 6 months from the onset of dissection: The false lumen shrank by > 50% in 93%, 75%, and 50% of patients. CONCLUSIONS: In cases of aortic dissection, the stent-graft is an effective tool for closing the entry site and promoting clot formation in the false lumen and for reducing the size of the false lumen within 6 months of the onset of dissection if the entry site has been closed.

Adult↗
PubMed1996

[Color Doppler sonographic assessment of intrahepatic hemodynamics and shunt patency after transjugular intrahepatic portosystemic shunt (TIPS)].

The usefulness of color Doppler sonography for the assessment of intrahepatic hemodynamics and shunt patency was evaluated in a total of eight patients in whom the intrahepatic hemodynamics before and after transjugular intrahepatic portosystemic shunt (TIPS) could be serially examined by color Doppler sonography. In six of these patients the serial sonographic examinations could be followed for more than one year after TIPS creation. Within one month after TIPS creation, Vmax in the shunt was ranged from 87 cm/sec to 242 cm/sec (mean: 142.5 cm/ sec), and the flow direction in the right anterior portal vein was reversed in all patients. More than 70% stenosis of the shunt could be diagnosed by color Doppler sonography. When the shunt was confirmed by angiography to be more than 70% stenotic or occluded, Vmax in the shunt was decreased to less than 50 cm/sec and the blood flow in the right anterior portal vein become hepatopetal. From three months before stenosis or occlusion of the shunt, it was confirmed that Vmax in the shunt was less than 70 cm/sec or the blood flow of right anterior portal vein was hepatopetal. Color Doppler sonography was useful for the assessment of intrahepatic hemodynamics, and shunt patency and prediction of shunt stenosis or occlusion following TIPS creation.

Adult↗
PubMed1996

[Balloon angioplasty and metallic stent].

Recently, interventional radiology (IVR) has been playing an important role as a treatment for the arterial occlusive diseases. Balloon angioplasty (PTA) is widely used for the stenotic lesions and clinical results are acceptable. However, some other procedures are frequently needed, and metallic stents (MS) are useful quite often. There are three main groups of stents: self-expanding stainless metallic stents (Z-stent, Wallstent), balloon-expandable stents (Palmaz stent, Strecker stent), and shape memory alloy stents, which are not clinically available for the iliac and femoro-popliteal arteries now in Japan except for Palmaz stent. However, it is expected that these MS will be available soon. In this paper we described the clinical utility of PTA and MS for the arterial occlusive diseases in the iliac and femoro-popliteal lesions based on our experience and past reports and also mentioned the future of IVR.

Angioplasty, Balloon↗
PubMed1996

[Correlation between MR imaging and histopathological findings of cystic metastatic brain tumors].

To clarify the correlation between the histopathological findings and MR signal intensity of the cyst wall, fifteen cystic metastatic brain tumors of eleven patients were imaged using a 0.5T MR unit just before surgery, and the MRI findings were correlated with the histopathological findings of resected lesions. On T2-weighted images, all cyst walls showed hypointensity. On T1-weighted images, the intensity of the cyst wall could be classified into three groups, compared with the cerebral cortex. Walls with hyperintensity on T1WI(group H; n = 6) consisted of ample tumor cells, blood vessels and connective tissues, suggesting viable tumor cells. Iso-intense walls on T1W1(group I; n = 3)had abundant reactive glial tissues. Hypointense walls on T1W1 (group L; n = 5)revealed hemorrhage and/or hemosicerin in the wall, suggesting hemorrhagic necrosis. Thus a good correlation was demonstrated between the MR signal intensities and histopathological findings of cyst walls of cystic metastatic brain tumors. This may contribute not only to more precise diagnosis on MRI but also to more planning for treatment of cystic brain metastases.

Adenocarcinoma↗
PubMed1995

Pharmacologic treatment of intimal hyperplasia after metallic stent placement in the peripheral arteries. An experimental study.

RATIONALE AND OBJECTIVES: To evaluate the efficacy of oral administration of cilostazol, an antithrombotic agent, for the prevention of thrombotic occlusion and intimal hyperplasia after stenting. METHODS: Single-bodied Z-stents were placed in the iliac arteries of 23 dogs. Before stenting, an embolizing coil was introduced into the right femoral artery to reduce blood flow in the right iliac artery. Eleven dogs were given cilostazol orally, and the other 12 were unmedicated as a control group. The dogs were killed at 4, 13, and 24 weeks. RESULTS: Intraluminal narrowing due to thrombus was observed in 25% of dogs in the control group but in none of the dogs in the cilostazol group. The thickness of the neointima was significantly thinner in the cilostazol group than in the control group at 24 weeks on the noncoiled side (P < 0.05), and at 4 and 24 weeks on the coiled side (P < 0.01). CONCLUSIONS: These results suggest that oral administration of cilostazol is an effective method of preventing thrombotic occlusion and intimal hyperplasia after stenting.

Administration, Oral↗
PubMed1995

Improved transjugular intrahepatic portosystemic shunt patency with PTFE-covered stent-grafts: experimental results in swine.

PURPOSE: To evaluate the ability of stent-grafts made with polytetrafluoroethylene (PTFE) graft material to improve transjugular intrahepatic portosystemic shunt (TIPS) patency. MATERIALS AND METHODS: TIPS were created in 13 swine by using PTFE-covered stent-grafts. Uncovered TIPS were placed in 13 other swine. Twenty-one of 26 animals were followed up with portal venography for 3 months or until the shunt became severely stenotic. Five animals without severe stenosis were sacrificed before 3 months because of illness. RESULTS: At 4 weeks after TIPS placement, nine of 13 stent-graft TIPS were patent (< 50% diameter narrowing) compared with only one patent stent in 13 uncovered TIPS. Six of 13 stent-graft TIPS remained patent until the animals were sacrificed. In 11 of 12 uncovered TIPS, stenosis was most prominent in the parenchymal tract. In five of seven stent-graft TIPS, stenosis was most prominent in the hepatic vein above the end of the graft material. Bile leaks were discovered in six occluded uncovered TIPS and in two of the stent-graft TIPS. CONCLUSION: PTFE-covered stent-grafts significantly improved TIPS patency in swine (P < .01). However, stenosis in the hepatic vein led to late shunt malfunction in selected cases.

Animals↗