Biomedical subjects

Naofumi Hayabuchi

Publications and source records attributed to Naofumi Hayabuchi.

At least 55 records · Page 3Linked to original sources

PubMed2003

Small peripheral pulmonary carcinomas evaluated with dynamic MR imaging: correlation with tumor vascularity and prognosis.

PURPOSE: To correlate the findings at contrast material-enhanced dynamic magnetic resonance (MR) imaging of small peripheral pulmonary carcinomas with tumor vascularity and prognosis. MATERIALS AND METHODS: Ninety-four patients with small peripheral pulmonary carcinomas who underwent surgical resection were examined retrospectively. Pathologic specimens were stained with hematoxylin-eosin and elastin-van Gieson. CD34 and vascular endothelial growth factor (VEGF) were assessed immunohistochemically. Delineated CD34-positive cells were counted as microvessels. Dynamic MR imaging was performed prior to and at 1, 2, 3, 4, 5, 6, and 8 minutes after injection of a bolus of gadopentetate dimeglumine. The two observers reviewed all images, and two pathologists performed all histologic analyses; a decision was determined with consensus. The maximum enhancement ratio (MER), the time lapse between the completion of the injection and the point of maximum signal intensity (Tmax), the washout ratio, and the slope value of the time-signal intensity curve were correlated with the microvessel density. VEGF-positive and VEGF-negative tumors were compared. All statistical analyses were performed by using nonparametric methods. RESULTS: The MER and the slope value were positively correlated, and the Tmax was negatively correlated (Spearman rank test, P <.0001, all comparisons) with the microvessel counts. The distribution of elastic and collagen fibers correlated with the washout ratio (Kruskal-Wallis test, P <.001). There was a statistically significant difference between the slope value of VEGF-positive tumors and that of VEGF-negative tumors (Mann-Whitney U test, P <.0001). Patients with VEGF-positive tumors had a significantly shorter overall survival than did those with VEGF-negative tumors (log-rank test, P <.0001). CONCLUSION: Dynamic MR imaging findings correlate with tumor vascularity and may be helpful in the prediction of prognosis.

Adenocarcinoma↗

PubMed2003

Is whole-brain irradiation necessary for primary central nervous system lymphoma? Patterns of recurrence after partial-brain irradiation.

BACKGROUND: Neurotoxicity after whole-brain irradiation remains a major problem in the treatment of primary central nervous system lymphoma (PCNSL). To clarify whether whole-brain radiation is necessary for PCNSL, the authors retrospectively analyzed the outcome of patients treated with partial-brain irradiation. METHODS: A nationwide survey was performed regarding the treatment of PCNSL. Among 62 institutions surveyed, 7 were identified in which whole-brain irradiation was not necessarily employed. Questionnaires were sent to these institutions and 43 patients who had been treated using partial-brain fields since 1985 were collected. Thirty-two patients had solitary lesions and 11 had multiple lesions. Patterns of recurrence could be identified in 38 patients. RESULTS: The cumulative in-field and out-field recurrence rates at 5 years were 57% and 49%, respectively. Of 14 out-field recurrences, 2 occurred at the safety margin of the previous radiation field. The out-field recurrence rate was 45% in patients with a single lesion and 67% in those with multiple tumors (P = 0.79). The out-field recurrence rate was 22% for patients treated with safety margins of > or = 4 cm and 83% for those treated with safety margins of < 4 cm (P = 0.0079). The median survival time and the 5-year survival rate were 28.5 months and 20%, respectively, in the former group of patients and 15 months and 11%, respectively, in the latter group (P = 0.057). CONCLUSIONS: Focal radiotherapy with safety margins of < 4 cm appears to be associated with a very high rate of out-field recurrence, but the use of a radiation field with generous safety margins (> or = 4 cm) appears to be worth further investigation.

Adolescent↗

PubMed2003

Stage I and II aggressive B-cell lymphomas of the head and neck: radiotherapy alone as a treatment option and the usefulness of the new prognostic index B-ALPS.

PURPOSE: To evaluate the outcome according to treatment modality and prognostic factors in clinical Stage I and II intermediate- or high-grade B-cell lymphomas of the head and neck. METHODS AND MATERIALS: We analyzed 155 patients treated between 1983 and 1997, excluding those with the Working Formulation low-grade lymphomas. Of these patients, 88 had Stage I and 67 had Stage II disease. Forty-one patients were treated with radiotherapy (RT) alone, and 114 patients were treated with a combination of RT and chemotherapy. Most of the chemotherapy regimens included anthracycline derivatives. More patients with Stage I disease and more patients with poor performance status were treated with RT alone. The treatment results were evaluated according to the new prognostic index B-ALPS, consisting of tumor bulk, age, lactate dehydrogenase level, performance status, and stage. RESULTS: The 5-year overall and failure-free survival rate was 71.5% and 68.3%, respectively, for all 155 patients. The 5-year survival rate was 67% for those treated with RT alone and 73% for those treated with radiochemotherapy (p = 0.13). Among the various potential prognostic factors, age >60 years, World Health Organization performance status 2-4, and tumor size >or=6 cm were associated with poorer survival. The 5-year survival rate was 82% for those with no or one B-ALPS factor, 66% for those with two factors, and 49% for those with three or more factors (p <0.0001). The B-ALPS index appeared to predict the prognosis of these patients better than did the International Prognostic Index. No single prognostic factor was useful to identify patient groups more suitable to treatment with RT alone, but in patients with two B-ALPS risk factors, those treated with radiochemotherapy had a better survival rate and tended to have a better failure-free survival rate than those treated with RT alone. CONCLUSION: A proportion of patients with clinical Stage I or II head-and-neck B-cell lymphoma may be successfully treated with RT alone. B-ALPS is a useful prognostic index in this disease.

Adult↗

PubMed2003

Spontaneous regression of extranodal malignant lymphoma occurred in the gingiva.

The spontaneous regression of malignant neoplasm is an extremely rare event. Here we report a case of extranodal malignant lymphoma occurring in the upper gingiva, which regressed spontaneously. A 78-year-old female had noticed a diffuse bucco-lingual swelling of the left maxillary gingiva in the incisor regions for a month, and she visited our department on 20 January 1999. Intraoral examination revealed diffuse swelling and redness in the maxillary gingiva of the incisor regions. Cervical and underarm lymphadenopathy was not detected. Surgical biopsy of the swollen gingiva revealed a malignant lymphoma, with diffuse large cells, B cell type. She was clinically staged as IE. After biopsy, the tumor spontaneously decreased in size; finally, the mass completely disappeared after 3 weeks. After regression, the lesions were externally irradiated with 30 Gy total dose. The patient has been free from disease for 36 months after regression.

Aged↗

PubMed2003

HTLV-1 carriers with B-cell lymphoma of localized stage head and neck: prognosis, clinical and immunopathological features.

Human T-lymphotropic virus type I (HTLV-I) is closely associated with T-cell lymphoma/leukaemia, which always shows monoclonal HTLV-1 provirus DNA integration. HTLV-1 is not associated with B-cell lymphoma. The relationship between B-cell lymphoma and HTLV-1 was analysed retrospectively in early stage B-cell non-Hodgkin's lymphoma (NHL) according to HTLV-1 infection and pathological features. We analysed 198 cases of head and neck B-cell NHL treated with radiotherapy and/or chemotherapy; 21 were seropositive and 177 were seronegative for HTLV-1. We also immunostained 26 cases of diffuse large B-cell lymphoma (DLBL), including 12 seropositive and 14 seronegative for HTLV-1 respectively, for CD20, CD3, CD4, CD8, CD56, MIB-1 and T-cell-restricted intracellular antigen (TIA-1) to examine the phenotype, immunity and proliferation activity. The 5-year overall survival rates were 78% and 49% (P = 0.007, log rank test) for HTLV-1 seronegative and seropositive cases respectively. Infection with HTLV-1 was significantly associated with poor survival in patients with B-cell lymphoma by multivariate analysis. For DLBL, HTLV-1 infection was not a significant factor, but the overall survival curve was similar to that of the 21 seropositive B-cell lymphoma cases. Lymphoma cells were negative for TIA-1, but the background lymphocytes were positive for this marker. The number of TIA-1-positive cells was higher in HTLV-1-negative cases than in-positive cases. In conclusion, patients with B-cell-NHL (B-NHL) who are also HTLV-1 carriers have a poorer prognosis than non-carriers. HTLV-1 does not seem to be associated with lymphomagenesis of the B phenotype itself, but correlates with host immunity by reducing the number of cytotoxic T-cells.

Adult↗

PubMed2003

Lung adenocarcinoma with mixed bronchioloalveolar and invasive components: clinicopathological features, subclassification by extent of invasive foci, and immunohistochemical characterization.

A significant proportion of small lung adenocarcinomas consists of two components: bronchioloalveolar carcinoma (BAC) and invasive carcinoma. The purpose of this study was to compare their clinicopathologic features with those of BAC and those of invasive cancer without BAC, and to define "early invasive" lesions based on the extent of invasive foci. We reviewed 484 lesions of resected lung adenocarcinoma and classified them into three groups according to tumor growth pattern: group 1 (n = 102, BAC), group 2 (n = 216, adenocarcinoma consisting of BAC and invasive carcinoma), and group 3 (n = 166, invasive adenocarcinoma without BAC component). Group 2 was further subdivided according to the extent of the invasive area: group 2a (n = 54), BAC with invasive foci 5 mm. These groups were compared with regard to their clinicopathologic features, expression of Ki-67 and p53, and expression of laminin-5, a putative marker for tumor invasion. The positivity rates of vascular, lymphatic, and pleural invasion in each group were as follows: 0%, 0%, and 0% in group 1; 5.5%, 14.8%, and 1.9% in group 2a; 45.7%, 41.4%, and 25.9% in group 2b; and 84.9%, 61.4%, and 60.8% in group 3. Notably, no lymph node metastasis occurred in either group 2a or group 1, but it was observed in 24.1% of group 2b and 47.0% of group 3. The mean Ki-67 labeling index, the frequency of p53 overexpression, and the frequency of laminin-5 overexpression increased from group 1 (11%, 4%, and 0%) to group 2a (16%, 20%, and 7%) to group 2b (24%, 41%, and 23%) to group 3 (35%, 38%, and 38%). In contrast, no clear differences were observed when lesions were subdivided according to size. Based on the distribution pattern of Ki-67-positive tumor cells, lesions were classified into two groups: marginal type (63%) and nonmarginal type (37%). The latter showed a significantly higher labeling index than the former. Moreover, the proportion of the marginal type clearly decreased from group 1 (85%) and group 2a (87%) to group 2b (55%) to group 3 (19%). Group 2 lesions showed characteristics intermediate between the BAC and invasive adenocarcinoma. According to the extent of the invasive area, we were able to define a subgroup of mixed-type adenocarcinomas (group 2a) that could be regarded as early invasive cancer because they showed low rates of vascular, lymphatic, and pleural invasion, and no nodal involvement.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMed2003

[Chemoradiotherapy for esophageal cancer].

Since mucosal (T1a) esophageal cancer is well controlled by endoscopic treatment, chemoradiotherapy (CRTx) is not indicated. However, for a submucosal (T1b, N0) esophageal cancer, CRTx may be the first line of treatment, since it can provide a good response rate, with an excellent survival rate comparable to that after esophagectomy. Definitive CRTx is also in the first line of treatment for a T4 esophageal cancer, because there was no difference in the survival rate between CRTx with surgery and CRTx without surgery in our trial. Esophagectomy is indicated only for non-responders or recurrence-salvage surgery. For patients with a potentially-resectable (T2-T3) esophageal cancer, esophagectomy offered a longer survival rate than CRTx did, in our series. However, there remains controversy over the efficacy of CRTx for a T2-T3 esophageal cancer. It has been reported by the National Cancer Center Hospital East Group that definitive CRTx provided the same survival rate as esophagectomy. A prospective trial comparing the survival rate after esophagectomy and that after CRTx for a T2-T3 esophageal cancer is needed.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2002

Study on the usefulness of whole body SPECT coronal image, MIP image in 67Ga scintigraphy.

In this study, we examined the usefulness of whole body coronal images and whole body cine display MIP images (CMIP) upon which image processing was carried out after whole body SPECT in comparison to the usefulness of whole body images (WB/SC) compensated by scattered radiation in tumor/inflammation scintigraphy with 67Ga-citrate (67Ga). Image interpretation was performed for the 120 patients with confirmed diagnoses, and the accuracy of their diagnoses was studied by three nuclear medical physicians and two clinical radiological technologists by means of sensitivity, specificity and ROC analysis. The resultant data show that sensitivity, specificity, accuracy and the area under the ROC curve Az in the WB/SC were approximately 65%, 86%, 74% and 0.724, respectively, whereas sensitivity, specificity, accuracy and Az of the image reading system in which CMIP is combined with whole body coronal images reconstructed by the OS-EM method were approximately 93%, 95%, 94% and 0.860, respectively. Furthermore, coronal images reconstructed by the OS-EM method tended to be superior to those produced by the FBP method in both diagnostic accuracy and ROC analysis. In conclusion, the image reading system in which CMIP is combined with whole body coronal images reconstructed by the OS-EM method was shown to be superior in diagnostic accuracy and ROC analysis. Our data suggest that whole body SPECT is an excellent technique as an alternative to WB/SC.

Adolescent↗

PubMed2002

Alveolar adenoma of the lung: computed tomography and magnetic resonance imaging findings.

Alveolar adenoma of the lung is a rare benign neoplasm with distinctive gross and microscopic findings. Radiographically, alveolar adenoma usually presents as a well-circumscribed, peripheral, solitary nodule. The authors describe the contrast-enhanced computed tomography and magnetic resonance imaging features of alveolar adenoma of lung. Magnetic resonance imaging demonstrated the presence of a cystic space with central fluid and thin-rim enhancement. These findings are suggestive of a benign nodule, and alveolar adenoma of lung should be added to the differential diagnosis of nodules that demonstrate this pattern of enhancement and are probably benign.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMed2002

Evolution of virtual CT laparoscopy for preoperative imaging in laparoscopic cholecystectomy.

The purpose of this study was to determine the feasibility of virtual endoscopy, named as "virtual CT laparoscopy", in the hepatobiliary system prior to laparoscopic cholecystectomy. We applied this technique to 28 patients suspected of having biliary disease. These images were compared and analyzed qualitatively based on visualization of the structures critical to operative cholangiography and surgical findings. Twenty-four patients, who underwent laparoscopic cholecystectomy, were evaluated as follows: the common bile duct and the hepatic duct were adequately visualized in 23 (96%) of the 24 patients, the cystic duct in 21 (88%), the gallbladder opacification in 20 (83%), the liver inferior surface in 20 (83%). Four patients had anatomic variations detected virtual CT laparoscopy and were proven by operative cholangiography and surgical findings. We emphasize that our new technique may contribute to the laparoscopy during surgery as the aid of understanding of anatomical structures in these organs.

Adult↗

PubMed2002

[Experimental study of pseudo-stenosis artifact on three-dimensional DSA].

Rotational three-dimensional digital subtraction angiography (3D-DSA) is very useful for interventional neuroradiology, especially in the endovascular therapy of cerebral aneurysms. However, pseudo-stenosis artifact on the vessel, which runs vertically to the rotational axis, was observed clinically. In this study, this artifact was confirmed in an experiment with 4.5-millimeter diameter vessel phantoms. The attenuation of the phantom at each degree of exposure (44 directions) was measured on the workstation (DSA pixel value). DSA pixel values were plotted from data of 10, 20, 30, 40, and 50 millimeter lengths, respectively. The saturated DSA pixel value of tangent projection on phantoms of 30 millimeters or more in length was observed. This phenomenon induces pseudo-stenosis artifact on 3D-DSA. The maximum reduction in the diameter of the phantom was 27.4% on the length of 50 millimeters. We confirmed that the two-dimensional data vertical to the rotational axis were inaccurate when a straight-coursed, long, segmented vessel was present. Under this special condition, vessels on 3D-DSA were displayed as smaller than their actual diameter.

Angiography, Digital Subtraction↗

PubMed2002

Clinical benefits of rotational 3D angiography in endovascular treatment of ruptured cerebral aneurysm.

BACKGROUND AND PURPOSE: Recent neurointerventional and neurosurgical technologies require an understanding of lesions and adjacent structures in three dimensions. To clarify the clinical benefits of rotational 3D digital subtraction angiography (DSA), we retrospectively analyzed its advantages and disadvantages at the time of interventional procedures for ruptured cerebral aneurysms. METHODS: From January 1998 through September 2000, 85 patients with a ruptured cerebral aneurysm were treated with Guglielmi detachable coils in the acute phase. Data for the patients treated before availability of 3D DSA (group A, 52 patients) were compared with data for patients treated after availability of 3D DSA (group B, 33 patients). Variables analyzed were age, sex, location of aneurysm, size of aneurysm, number of implanted coils, number of DSA exposures, and total amount of contrast medium used. RESULTS: No statistically significant differences between the groups were noted when we compared the age, sex, aneurysm location, aneurysm size, and number of implanted coils. The number of DSA exposures was decreased in total by using 3D DSA (P <.0001), not only to determine the working projection (P <.0001) but also during the procedure (P <.0002). However, no statistically significant difference was noted in the comparison of total amount of contrast medium. CONCLUSION: Three-dimensional DSA allows acquisition of high-quality 3D images of cerebral arteries and also allows observation and analysis from multiple directions to determine the appropriate working projection for embolization. Three-dimensional DSA is essential for optimal diagnosis and embolization of cerebral aneurysms and can reduce the number of exposures.

Adolescent↗

PubMed2002

[Laser-radiation therapy for T2N0M0 laryngeal-glottic cancer].

PURPOSE: To evaluate the laser-radiation combined therapy for T2N0M0 laryngeal-glottic cancer in order to preserve the larynx. METHODS AND MATERIALS: The subjects consisted of 52 patients with T2N0M0 laryngeal-glottic cancer treated with laser-radiation combined therapy between 1980 and 1999. Patients ranged in age from 40-88 years, with a median of 70 years, and included 51 men and one woman. During this period, treatment was administered with different radiation devices(60Co or 4 MV-X ray), and 40-72 Gy (median, 60 Gy) of radiation therapy ware administered. Tumor and treatment characteristics were correlated with local control at a median follow-up of 61 months(range 12-210 months). Concurrent chemotherapy was administered to 32 patient; 29 were treated with 5-FU and vitamin A(FAR), and 3 were treated with low-dose CDDP. Post treatment vocal function was examined in 37 patients. The voice was evaluated in terms of four parameters: maximum phonation time (MPT), mean air flow rate during phonation over a comfortable duration(MFR), fundamental frequency range of phonation(F0 range), and sound pressure level range of phonation (SPL range). RESULTS: The five-year cause-specific-survival rate was 98.0%, and the local control rate was 91.8%. Three of 4 patients who had locally relapsed were administered total laryngectomy as salvage therapy. One patient was administered the tracheostomy for late complication. The actuarial laryngeal preservation rate was 92.3%. We did not find any significant relationship between local relapse and extent of disease, subglottic extension, or anterior commissure involvement. Concurrent chemotherapy was not a significant prognostic factor. Laser debulking followed by radiation therapy did not change the voice significantly except the F0 range. CONCLUSION: We conclude that the laser-radiation combined therapy for T2N0M0 laryngeal-glottic cancer was effective therapy for not only preservation of the voice but also for vocal function.

Adult↗

PubMed2001

[Physical and imaging properties of heavy metal filter combinations in chest radiography]

We have investigated the performance characteristic of the heavy metal filters with higher atomic numbers by comparing their patient exposures, tube loadings, radiographic contrasts, and noise Wiener spectra with those of a combination of copper and aluminum filter which has been used widely in chest radiography. Seven heavy metal filters were used for this study. As for a tungsten filter, two filters different in thickness were used. One is 0.05 mm thick, and the other 0.10 mm. The other metal filters were respectively combined with a tungsten filter with a thickness of 0.05 mm. Among the all filters investigated, tube loading of tungsten filter with 0.05 mm thick is minimum. Tungsten with 0.1 mm thick and tungsten with 0.05 mm+ barium show the larger advantages in patient exposure than those of the other filters. It was found that the magnitude of patient exposure varied slightly with the difference of image receptor used. The use of heavy metal filters showed the small advantages in the patient exposure reduction ( approximately 20%) compared with that of conventional copper filter. The use of heavy metal filters showed increasing tube loading ( approximately 5 times) compared with that of conventional copper filter. Noise Wiener spectra of heavy metal filters showed comparable with those of conventional copper filter. In conclusion, the use of heavy metal filter combinations offer no significant advantages over optimal conventional filters.

Journal Article↗

PubMedDate not supplied

High-resolution computed tomographic angiography/computed tomographic cholangiography image fusion of the hepatobiliary system.

The 3-dimensional image was excellent as a result of the fast scanning and narrow collimation using multidetector computed tomography (CT); and the parallel escalation in the capabilities of the workstation allow the use of CT angiography/CT cholangiography image fusion. We demonstrated the feasibility of fusion images of the hepatobiliary system. We believe that fusion images are extremely valuable for applications such as preoperative planning for hepatic and bile duct resection.

Angiography↗

PubMedDate not supplied

Rotational three-dimensional cholangiography--initial clinical experience.

PURPOSE: The purpose of this study was to evaluate the feasibility and image quality of a novel biliary imaging technique that obtains 3D cholangiography image sets by infusing contrast material through a PTC-drainage tube, using 3D-digital subtraction angiography (DSA). METHODS: We applied this technique to seven patients suspected of having biliary disease. All patients underwent PTCD because of obstructive jaundice. Contrast material was introduced through the drainage tube, and the raw data were then transferred automatically to a workstation. Approximately 3 minutes of user time was required to generate the 3D images following image acquisition. RESULTS: Three-dimensional cholangiography was obtained in all patients who underwent 3D-DSA examination. Acceptable quality 3D-DSA cholangiograms were generated in six of the seven patients. CONCLUSION: We emphasize that our new technique may help during surgery as an aid to understanding anatomical structures in the biliary system.

Aged↗

PubMedDate not supplied

Assessment of pancreatic CT enhancement using a high concentration of contrast material.

OBJECTIVE: To evaluate the usefulness of pancreatic enhancement using a high concentration of contrast material in CT. METHODS: We performed abdominal CT on 125 patients after dividing them at random into five groups with two different concentrations, two different injection rates and three different injection doses: group A: 100 ml, 300 mgI/mL, 3 mL/sec; group B: 2 mL/kg, 300 mgI/mL, 3 mL/sec; group C: 1.5 mL/kg, 370 mgI/mL, 3 mL/sec; group D: 2 mL/kg, 300 mgI/mL, 5 mL/ sec; and group E: 1.5 mL/kg, 370 mgI/mL, 5 mL/sec. Among these five groups, the two groups given a concentration of 370 mgI/mL received a dose of 1.5 mL/body weight. RESULTS: The peak enhancement value of the pancreas was significantly greater in group E than in groups A and B. However, no statistically significant differences were found among the other groups. CONCLUSION: The fast injection rate using the high concentration of contrast medium provided greater enhancement of the pancreas than the slow injection rate using the routine concentration of contrast medium, and pancreatic CT enhancement depended more on the dose of iodine per second than on that of total iodine.

Adult↗

PubMedDate not supplied

Distal-tip shape-consistency testing of steam-shaped microcatheters suitable for cerebral aneurysm coil placement.

BACKGROUND AND PURPOSE: Although the selection of microcatheter for endovascular aneurysmal treatment is one important factor in patient outcome, the use of steam shaping for achieving safe entry and stability during coil placement has not, to our knowledge, been systematically evaluated. The goal of this study was to compare the durability of distal microcatheter steam shaping in five different catheters with typical intraprocedural stresses that are similar to those encountered during aneurysm coil placement. METHODS: Distal tips of microcatheters were shaped into a 90 degrees turn with distal straight-segment lengths of 3, 5, or 7 mm by using steam, performed according to the instructions for use included with each catheter. In a water bath kept at body temperature, the changes in catheter tip angle were recorded and measured following microcatheter insertion into a guiding catheter, microguidewire insertion through the microcatheter, and Guglielmi detachable coil (GDC) placement through the microcatheter. RESULTS: The degree of distal microcatheter straightening with typical intraprocedural manipulations was more pronounced on braided microcatheters and on microcatheters with 3- or 5-mm distal-shaped segments. The degree of spontaneous recovery of the initially steamed shape was more pronounced with nonbraided catheters. The most significant single variable contributing to straightening of a steam-shaped catheter tip was the effect of microguidewire insertion. The catheter-tip straightening effect encountered with inserting GDCs was less than that encountered with microguidewire insertion. We demonstrated that the decreased catheter-tip angle encountered with a large-magnitude straightening stress spontaneously recovered once the stress was removed or when it was reduced to a smaller magnitude stress. CONCLUSION: Our study shows that, although braided microcatheters are suitable for maintaining durable configurations when long distal-tip lengths are permissible, nonbraided microcatheters demonstrate the most durable distal-tip configurations when short distal-tip lengths are called for. This may be one of significant factors in catheter choice for endovascular treatment of aneurysm.

Catheterization↗