Si-Wa Chan

Taichung Veterans General Hospital, 臺中市, Taiwan, Taiwan

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Publications (14)16.22 Total impact

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    ABSTRACT: The purpose of the technical note is to introduce the complex coil assisted coil embolization method in the treatment of intracranial small aneurysm, in order to enhance the safety of the procedure. The first microcatheter was navigated into the aneurysm sac and the ultrasoft coil was used as the embolization coil. If the embolizations coil could not stay within the aneurysm sac smoothly, such as coil herniation into parent artery during the delivery process. The second microcatheter would be navigated to the aneurysm level in the parent artery. Another complex coil was delivered within the parent artery via the second microcatheter to provide the neck bridge effect in order to enhance the stability of embolization coil. Besides, the protection coil will not disturb the parent artery flow. While the embolization coil was put into the aneurysm sac smoothly under the help of complex protective coil, the protective coil was then withdrawn gently. We use the most magnified view, dual-plane approach simultaneously to observe the stability of embolization coil. The embolization coil would be detached without any evidence of coil motion or vibration. The new method could provide the physiological protective method, without leaving any protective device such as stent within the parent artery.
    Preview · Article · Sep 2013
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    ABSTRACT: Systemic and fatal arterial air embolism during the computed tomography (CT) scan is rarely reported in English-based literature. Iatrogenic air embolism happening during the CT scan is often related to the injector, usually venous air embolism and asymptomatic. We report one fatal and extensive systemic arterial air embolism because of one error that happened during a brain CT scan. The mechanism is different from the reported cases in the literature. The possible mechanism and pathogenesis are well discussed to alert clinicians and prevent the recurrence of such complication.
    Full-text · Article · Apr 2011 · Journal of the Chinese Medical Association
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    ABSTRACT: With the increased availability of multi-detector row CT, indirect CT venography has become an important non-invasive image modality for patients with suspected deep vein thrombosis. Use of indirect CT venography can not only diagnose/exclude deep vein thrombosis, but can also determine if there are other anomalies or diseases which might contribute to the patient's symptoms. In this pictorial essay, we introduce the scanning protocol, post-processing techniques, and interpretation algorithm used in widely available 64 multi-detector row technology. We discuss several cases, including deep vein thrombosis in acute and chronic stages, anatomic variation, vena cava filter, and collateral veins. Lastly, we consider alternative diagnoses including varicose veins, infection, prosthesis failure of arthroplasty, traumatic vessel injury, and other musculoskeletal conditions. Radiologists should be familiar with the comprehensive interpretation of indirect CT venography to facilitate differential diagnosis and further treatment decision.
    No preview · Article · Dec 2010 · The international journal of cardiovascular imaging
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    ABSTRACT: OBJECTIVE: Patent arteriovenous fistula (AVF) is related to better prognosis and quality of life for patients on long-term dialysis. When AVF dysfunction is suspected, MDCT is a good noninvasive tool for evaluating the entire AVF structure and determining reversible conditions for treatment. The aim of this article is to introduce the scanning and interpretation techniques and to illustrate the conditions related to early and late fistula failures. CONCLUSION: MDCT is a fast, noninvasive, and accurate technique for diagnosing AVF complications. Radiologists familiar with these techniques can help to improve the prognosis and quality of life for hemodialysis patients.
    No preview · Article · Mar 2010 · American Journal of Roentgenology
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    ABSTRACT: Recently, CT pulmonary angiography (CTPA), especially performed with multi-detector row CT, has become a key imaging modality for pulmonary embolism. However, CTPA that was performed under clinical suspicion of pulmonary embolism has been shown to lead to high prevalence of alternative diagnosis, up to 25.4%. A comprehensive evaluation of pulmonary and extrapulmonary abnormalities including cardiovascular lesions is critical in proper diagnosis and patient care. Radiologists should be familiar with the comprehensive interpretation of CTPA to facilitate differential diagnosis and further treatment decision.
    No preview · Article · Feb 2010 · The international journal of cardiovascular imaging
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    Full-text · Article · Feb 2010 · The international journal of cardiovascular imaging
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    ABSTRACT: To evaluate the safety and protective effect of relative undersized coil with loose coil core in the clinical dilemma condition--very small (43.0 mm) ruptured intracranial aneurysm. We studied 12 patients (4 men, 8 women) who had suffered from acute ruptured small intracranial aneurysms (2-3 mm in size, with SAH presentation). All subjects underwent a single coil embolization procedure. An undersized coil (equivalent to the neck size or 0.5 mm smaller than the aneurysm diameter) was chosen as the embolizer. Based on the postembolization angiogram, subjects were divided into 2 groups. One was labeled as the initial complete obliteration group (NR) and the other as the incomplete obliteration group (SR). Fisher exact test and the Wilcoxon rank sum test were used to for statistical analysis. The technical success rate was 100% without any procedure-related complication. The follow-up interval ranged from 6 to 32 months. No episode of rebleeding or coil migration could be defined in the admissive and following period. Loose coil core were seen in all patients. The total recurrent rate was 8.3% (1/12); only one patient suffered from recurrent lesion in SR group. The preliminary result showed that under-sized coil packing with loose coil core could provide the protective effect and prevent from further rebleeding for very small ruptured aneurysms. It should be considered as an alternative option in the treatment of acute ruptured very small aneurysms when other conventional strategies are not feasible.
    No preview · Article · Dec 2009 · Surgical Neurology
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    ABSTRACT: Trans-sternal percutaneous computed tomography (CT) guided biopsy for mediastinal mass is a difficult but feasible procedure. In the literature there have only been reports from four medical centers in western countries. Herein we report a case of 57-year-old man with a 38mm-sized mass in anterior mediastinum. Since the tumor access was blocked by both sternum and aortic arch branches, trans-sternal percutaneous CT-guided biopsy was the only possible way for tissue proof. The planning, imaging, and technique considerations of this procedure are discussed. With this particular case, we confirmed the feasibility of trans-sternal percutaneous CT-guided core biopsy in the Taiwanese population.
    Full-text · Article · Dec 2009 · Zhonghua fang she xian yi xue za zhi = Chinese journal of radiology
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    ABSTRACT: OBJECTIVE: CT-guided core biopsy is playing an increasing role in the diagnosis of benign disease, cellular differentiation, somatic mutation analysis, and molecular fingerprint analysis. CONCLUSION: In this article, we summarize the basic concepts, protocols, and techniques that we use for CT-guided core biopsy of lung lesions to assist radiologists in obtaining diagnostic specimens while reducing preventable complications.
    No preview · Article · Nov 2009 · American Journal of Roentgenology
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    ABSTRACT: To compare the image quality and interpretability of two delayed phase protocols of cardiac CT under the same low radiation dose: prospective ECG-triggering sequential scan (modified from the calcium score protocol) versus retrospective ECG-gating spiral scan with ECG-pulsing. From March to April of 2007, in all the patients referred for cardiac CT, prospective ECG-triggering sequential scan was used for the delayed phase. In May and June, retrospective ECG-gating spiral scan was used in all such patients. The radiation dose was pre-calculated to match the two protocols. The marginal sharpness, slab artifact and beam hardening artifact were graded 1 (worst) to 5 (best) semi-quantitatively for comparison. Grades 1 and 2 were considered uninterpretable. In addition, the demographic data of the patients, image noise, scan time, and radiation dose by dose-length-product were compared. After excluding patients with known coronary artery disease or myocardial lesions, each group included 31 patients for comparison. The prospective ECG-triggering sequential scan rated good in less noise and better marginal sharpness, and the retrospective ECG-gating spiral scan rated good in less slab and beam hardening artifact. Considering the interpretability, in the sequential group, 41.9% and 85.5% of scans were uninterpretable due to severe slab and beam hardening artifact, respectively, whereas the spiral group reached 100% interpretability. Conclusion: Under the similar low radiation dose, retrospective ECG-gating spiral scan with ECG-pulsing should be used instead of prospective ECG-triggering sequential scan (modified from the calcium score protocol) for delayed phase of cardiac CT. The sequential protocol is not clinically feasible due to severe slab and beam hardening artifact in a significant portion of patients.
    Full-text · Article · Jun 2009 · Zhonghua fang she xian yi xue za zhi = Chinese journal of radiology
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    ABSTRACT: Subdural hematoma (SDH) of the spine following intracranial hemorrhage is extremely rare. We present a 35-year-old woman who suffered from headache and dizziness initially, and then lower back pain, lower limb weakness and paraparesis gradually developed within 1-2 weeks. Magnetic resonance imaging revealed intracranial and spinal SDH. No vascular abnormality was seen by brain and spinal angiography. Platelet count, prothrombin time, activated partial thromboplastin time, and inflammatory markers, including C-reactive protein, were normal. A diagnosis of spontaneous spinal and intracranial SDH was then confirmed surgically. Postoperative recovery was uneventful.
    No preview · Article · Apr 2009 · Journal of the Formosan Medical Association
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    ABSTRACT: Gastrointestinal stromal tumors (GISTs) are specific, generally Kit (CD117)-positive, mesenchymal tumors of the gastrointestinal tract encompassing a majority of tumors previously considered gastrointestinal smooth muscle tumors. Our aim was to characterize the computed tomographic findings and predict malignant risk from computed tomography for the evaluation of GISTs. The computed tomographic images of 39 patients with pathologically and immunohistochemically proven GISTs were reviewed by 2 radiologists, and the final interpretations were reached by consensus. Images were assessed for the size, contour, growth pattern, boundary, degree of enhancement, and necrosis of the tumors. The presence of calcification within the lesions, abdominal lymphadenopathy, ascites, and bowel obstruction were also recorded. Categorical variables were compared using Fishers exact test. Univariate and multivariate logistic regression analyses were used for selection of significant predictors of high-risk malignancy. In addition, the relationships between computed tomographic features and tumor size were assessed by means of nonparametric univariate analysis with the MannWhitney U test and KruskalWallis test. Both old age and larger tumor size (>or= 5 cm) were statistically significant in the univariate logistic analysis for high-risk malignant tumors (p < 0.25). However, in multivariate logistic regression, only larger tumor size (>or= 5 cm) was found to have final statistical significance for high-risk malignant GISTs (p < 0.05). In addition, more exophytic growth pattern (p < 0.01), more lobulated appearance (p < 0.01), good enhancement (p < 0.05),and more necrosis (p < 0.01) of masses were more often observed in larger GISTs than small ones on computed tomography. Larger tumor size (>or= 5 cm) was found to have a predictive value with respect to high-risk malignant GISTs.
    Full-text · Article · Oct 2007 · Journal of the Chinese Medical Association
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    Hsin-Hui Huang · Si-Wa Chan · Yeu-Sheng Tyan
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    ABSTRACT: A 73-year-old man presented with chest pain and shortness of breath. He received esophageal reconstruction with gastric tube via retrosternal route five years ago due to gastroesophageal reflux disease (GERD) and severe esophageal stricture. At emergency department, the chest radiography and computed tomography (CT) disclosed abnormal air and fluid collection in the pericardial cavity. Under the impression of hollow organ perforation into the pericardial cavity, the patient received emergent pericardiectomy to relieve the cardiac tamponade. Surgery revealed a fistula between the pericardial cavity and the reconstructed gastric tube. Total gastrectomy, feeding duodenostomy and pericar-dial drainage were performed in the operation. After surgical intervention, the patient recovered uneventfully and was discharged 3 weeks later. Pneumopericardium indicated air in the peri-cardial cavity. Reviewing the literature, pneumo-pericardium have been reported in association with various causes, such as transdiaphragmatic perfo-ration of gastric ulcer [1], blunt chest trauma [2], inflammatory process[3] , or after various iatrogenic procedures including pacemaker implantation [4] and cardiac transplantation [5]. Cases of spontaneous pneumothorax and pneumopericardium after heavy lifting have also been reported [6]. Only three cases of pneumopericardium secondary to communication with the reconstructed esophagus have been reported in the literature, two of them died in spite of sur-gical correction [7, 8]. We herein report a patient of pneumopericardium caused by fistula from the reconstructed esophagus. This patient presented with unusually mild symptoms and good postoperative recovery.
    Preview · Article · Aug 2006
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    ABSTRACT: Only few cases of spinal subdural empyema has been reported in the literature and the pre- operative diagnosis is much less. Due to the advance of magnetic resonance imaging techniques, we reported a 75 years old female with spinal sub- dural empyema. She was a diabetic patient and received laminectomy, complicated with vertebral body osteomyelitis about 15 years ago at the 4th and 5th vertebral body of lumbar region (L4/5). She is a victim of cervical cancer and currently suf - fered from leukocytosis, high fever and then low back pain for several weeks. Magnetic resonance imaging clearly depicts the picture of osteomyelitis at L4/5 with mixed epidural and subdural abscess. The subdural lesion extended upwardly from L4 to T11 (the 11th vertebrae of thoracic spine) level. Laminectomy and durectomy were performed soon and clearly revealed the picture of long segment subdural abscess. Post-operation recovery course is fine.
    No preview · Article · Jan 2006