Biomedical subjects

Bernard Yan

Publications and source records attributed to Bernard Yan.

6 recordsLinked to original sources

PubMed2006

Single-center experience with TruFill platinum coils for the embolization of cerebral aneurysms.

Endovascular coiling has become a powerful alternative to neurosurgical clipping of cerebral aneurysms. Apart from the Guglielmi Detachable Coil (GDC) (Boston Scientific, Galway, Ireland), there is limited published data about the newer generation of detachable platinum coils, e.g., TruFill (Cordis, Johnson and Johnson, Miami, Fl.). We report our initial clinical experience with the embolization of aneurysms by TruFill coils. Included in this retrospective study were 26 patients (age 55.4+/-14.5 years; 9 male, 17 female) with 28 aneurysms, 21 ruptured and 7 unruptured. All patients were treated exclusively by embolization with TruFill platinum coils. Immediate angiographic and 6-month angiographic follow-up results were documented. Acute clinical outcome was recorded. Of the 28 aneurysms, 16 (57%) were completely occluded by TruFill embolization, 11 (39%) were incompletely occluded with residual necks, and 1 (4%) was partially occluded as residual aneurysm. There were no aneurysmal ruptures during the procedures. Follow-up at 6 months after the procedure was available in 18 patients and 19 aneurysms. Of the 19 aneurysms, 2 of 12 initially completely occluded aneurysms (17%) and 1 of 7 aneurysms with initial residual necks (14%) showed recanalization at the 6-month follow-up. One recanalized aneurysm was subsequently recoiled with consequent residual neck and remained unchanged at the 1-year follow-up. Embolization by TruFill platinum coils has a comparable total aneurysmal occlusion rate to that with GDC. The mid-term reintervention rate is low, and will require verification by future long-term studies.

Cerebral Angiography↗

PubMed2006

Application of different methods for nuclear shape analysis with special reference to the differentiation of brain tumors.

OBJECTIVE: To study the discriminatory power of different methods designed for nuclear shape analysis with reference to the differentiation and grading of brain tumors and the differentiation between proliferating and nonproliferating nuclei. STUDY DESIGN: At least 300 tumor cell nuclei per case were measured by means of a digital image analysis system. Fourier amplitudes no. 1 to 15, moments no. 1 to 7 according to Hu, roundness factor, ellipse shape factor, concavity factor, Feret ratio, fractal dimension and bending energy were determined for each nucleus. The discriminatory power of these parameters was tested in three pairwise comparisons: (1) oligodendrogliomas WHO grade II (n = 13) vs. grade III (n = 11), (2) medulloblastomas WHO grade IV (n = 14) vs. anaplastic ependymomas WHO grade III (n = 12), (3) Ki-67-positive vs. Ki-67-negative tumor cell nuclei in the 14 medulloblastomas. RESULTS: When data from Fourier analysis were included in statistical analysis, cross-validated discriminant analysis led to a 100% correct reclassification for the first and for the second pairwise comparison and to a 75% correct reclassification when comparing Ki-67-positive and Ki-67-negative nucleifrom medulloblastomas. Different combinations of the other shape parameters led to a lower percentage of correctly reclassified cases for all three pairwise comparisons, especially when Fourier analysis was not included in the analysis. CONCLUSION: Fourier analysis provided an optimal statistical discrimination between different brain tumor entities and between data sets from proliferating and nonproliferating tumor cell nuclei. Since nuclear shape is an important criterion for the investigation of tumors, the application of Fourier analysis is therefore recommended for quantitative histologic investigations in neuro-oncology.

Brain Neoplasms↗

PubMed2005

When to measure lipid profile after stroke?

BACKGROUND: Although acute decreases in total cholesterol (TC) are well documented in myocardial infarction, previous stroke studies have produced conflicting results. The timing of lipid estimation in ischemic stroke is becoming important with recent trial results indicating the benefits of statins. We therefore aimed to determine the optimal time for lipid measurements after stroke. We hypothesized that TC would acutely decrease after stroke and return to baseline by 12 weeks. METHODS AND RESULTS: We performed a prospective, observational study of 50 patients (age 68.5 +/- 11.2 years) who presented with acute ischemic stroke. Of these, 22 (44%) were HMG-CoA reductase (statin) naïve, 15 (30%) had already been on statins and 13 (26%) were commenced on statins. Of the 50 patients, 38 (76%) completed 12 weeks of follow-up, 5 died, and 7 were lost to follow-up. Fasting lipid profile (TC, low-density lipoprotein, high-density lipoprotein, triglyceride) was measured <48 h, 4 weeks and 12 weeks following ictus. In patients who were statin naïve, there was a significant increase in TC at the week 12 evaluation. CONCLUSIONS: Cholesterol levels in acute stroke are an unreliable measure of lipid status. Initiation of statins should ideally be based on measurements taken 12 weeks after stroke.

Acute Disease↗

PubMed2005

Fourier analysis of intracranial aneurysms: towards an objective and quantitative evaluation of the shape of aneurysms.

Shape irregularities of intracranial aneurysms may indicate an increased risk of rupture. To quantify morphological differences, Fourier analysis of the shape of intracranial aneurysms was introduced. We compared the morphology of 45 unruptured (UIA) and 46 ruptured intracranial aneurysms (RIA) in 70 consecutive patients on the basis of 3D-rotational angiography. Fourier analysis, coefficient of roundness and qualitative shape assessment were determined for each aneurysm. Morphometric analysis revealed significantly smaller coefficient of roundness (P < 0.02) and higher values for Fourier amplitudes numbers 2, 3 and 7 (P < 0.01) in the RIA group, indicating more complex and irregular morphology in RIA. Qualitative assessment from 3D-reconstructions showed surface irregularities in 78% of RIA and 42% of UIA (P < 0.05). Our data have shown significant differences in shape between RIA and UIA, and further developments of Fourier analysis may provide an objective factor for the assessment of the risk of rupture.

Adult↗

PubMed2004

Serum S100B predicts a malignant course of infarction in patients with acute middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: Early predictors of infarct volume may improve therapeutic decisions in patients with acute cerebral ischemia. We investigated whether measurements of serum astroglial protein S100B can predict a malignant course of infarction in acute middle cerebral artery (MCA) occlusion. METHODS: We included 51 patients (24 women, mean age 69.1+/-12.4 years) admitted within 6 hours after stroke symptom onset caused by proximal MCA occlusion, as shown by magnetic resonance angiography (n=39), intra-arterial angiography (n=4), or transcranial duplex sonography (n=8). Blood samples were drawn at hospital admission and 8, 12, 16, 20, and 24 hours after symptom onset. Serum S100B concentrations were determined using a fully automated immunoluminometric assay. A malignant course of infarction was defined as the occurrence of clinical signs of cerebral herniation within the first 7 days of treatment or the clinical decision to perform decompressive hemicraniectomy caused by critical space-occupying swelling as detected by repeated neuroimaging. RESULTS: Sixteen patients developed malignant infarction (31%). Beginning with the 12-hour value, mean S100B serum concentrations were significantly higher in patients with a malignant course compared with those without (12 hours 1.23+/-1.24 versus 0.29+/-0.45 microg/L; 16 hours 1.80+/-1.65 versus 0.38+/-0.53 microg/L; 20 hours 1.90+/-1.53 versus 0.44+/-0.48 microg/L; and 24 hours 2.41+/-1.59 versus 0.57+/-0.66 microg/L; all P<0.001). A 12-hour S100B value >0.35 microg/L predicted malignant infarction with 0.75 sensitivity and 0.80 specificity. A 24-hour value >1.03 microg/L provided 0.94 sensitivity and 0.83 specificity. CONCLUSIONS: The serum marker S100B can predict a malignant course of infarction in proximal MCA occlusion. This finding may improve the identification and monitoring of patients at particularly high risk for herniation.

Acute Disease↗

PubMedDate not supplied

Three-dimensional rotational dacryocystography for imaging of the lacrimal draining system and adjacent anatomical structures.

PURPOSE: A three-dimensional (3D) rotational angiography system was used to perform 3D dacryocystography (3DRD) as an adjunct to the conventional dacryocystography assisted by digital subtraction angiography (DSA). METHODS: In 15 patients with severe epiphora, 3DRD was performed after inconclusive results from DSA-assisted dacryocystography. RESULTS: 3DRD was technically feasible and well tolerated in all 15 cases. In 5 out of 15 patients, 3DRD, in contrast to DSA-assisted dacryocystography, distinguished clearly between stenotic lesions of the canaliculi, lacrimal sac or nasolacrimal duct. In 10 cases, the simultaneous display of tear ducts and adjacent structures of the nasal cavity provided critical anatomical information for decision making between endoscopic and open dacryocystorhinostomy. CONCLUSIONS: 3DRD is technically feasible and adds important information to conventional DSA-assisted dacryocystography.

Aged↗