Biomedical subjects

Yiu-Wah Li

Publications and source records attributed to Yiu-Wah Li.

15 recordsLinked to original sources

PubMed2006

Coronary artery anatomy in children with congenital heart disease by computed tomography.

AIMS: To evaluate electron beam computed tomography (EBCT) for recognition of coronary artery patterns in children with congenital heart diseases. METHODS: Institutional review board approval was obtained; informed consents were not required. A total of 226 children diagnosed with Tetralogy of Fallot (n=122), double outlet right ventricle (n=52), transposition of the great arteries (n=34), and congenitally corrected transposition (n=18) who had undergone cardiac EBCT at our institution between 1995 and 2002 were identified. Iodinated contrast medium was injected with arterial phase acquisition. The two radiologists and one pediatric cardiologist that interpreted the EBCT images and cardiac angiograms, respectively, were blinded to each other's results. Surgical and cardiac angiogram findings were compared to the EBCT results. Descriptive statistics were used to compare efficacy. RESULTS: Numerous aberrant patterns were clearly identified on the EBCT images. Pattern IX occurred in most patients with Tetralogy of Fallot or double outlet right ventricle. Patterns I and 0 are the most common coronary artery types in transposition of the great arteries and congenitally corrected transposition, respectively. Overall diagnostic accuracy for all disease groups was 82.7%. The diagnostic accuracy of the coronary arterial anatomy by EBCT increased with older age, and was more than 90% in individuals aged over 3 months. CONCLUSION: EBCT is effective for identification of the coronary anatomy of children with specific congenital heart diseases, except for neonates and small infants less than 3 months of age.

Adolescent↗

PubMed2006

Magnetic resonance imaging of seminal vesicle cyst associated with ipsilateral urinary anomalies.

BACKGROUND: Seminal vesicle cysts rarely cause symptoms. Data on long-term follow-up from childhood to adulthood are lacking. The study analyzed the magnetic resonance imaging (MRI) and follow-up results of this condition. METHODS: From 1991 to 1996, seminal vesicle cyst was diagnosed in 13 boys (mean age, 12 years; range, 7-15 years), six of whom had long-term follow-up data. The clinical symptoms and MRI findings at diagnosis and at follow-up were analyzed. RESULTS: The seminal vesicle cyst was on the right side in six patients and on the left in seven. The size varied, ranging from 1.0 x 1.3 x 1.4 to 4.4 x 3.1 x 3.6 cm. All showed high signal intensity on T2-weighted images but variable signal intensity on T1-weighted images. Associated urinary tract anomalies included renal anomalies (dysplasia in 2 patients, agenesis in 11), ectopic ureteral orifice (11), hydroureter (6), and vertebral anomalies (2). One of the six patients with follow-up had repeated urinary tract infection and underwent surgical resection of the cyst 8 years after the diagnosis. The other five had no symptoms during the follow-up period. Three of the six patients had repeat MRI after a median of 11 years, which showed slight cyst enlargement and increased T1-weighted signal intensity. CONCLUSION: Most seminal vesicle cysts were asymptomatic and did not change during long-term follow-up. MRI is a powerful tool for detecting seminal vesicle cysts and in delineating associated congenital anomalies of the urogenital tract.

Adolescent↗

PubMed2005

Anomalous brachiocephalic vein: CT, embryology, and clinical implications.

OBJECTIVE: CT patterns of anomalous brachiocephalic veins are presented with reconsideration of the structure's embryogenesis. CONCLUSION: With advancements in central line procedures and corrective cardiac surgery, and the widespread use of noninvasive imaging techniques, the clinical importance of identification of the anomalous brachiocephalic vein is shown.

Adolescent↗

PubMed2003

Usefulness of three-dimensional electron beam computed tomography for evaluating tracheobronchial anomalies in children with congenital heart disease.

This study was undertaken to delineate tracheobronchial anomalies associated with congenital heart disease. From June 1995 to December 2000, 1,245 children with congenital heart disease underwent cardiac electron beam computed tomography with 3-dimensional reconstruction on an independent workstation. Tracheobronchial anomalies are strongly associated with congenital heart disease and accompanying tracheal stenosis is not uncommon. With 3-dimensional reconstruction, electron beam computed tomography provided excellent anatomic definition of the central tracheobronchial abnormalities.

Abnormalities, Multiple↗

PubMed2003

Mature cystic teratoma of the pancreas in a child.

A cystic pancreatic tumour is rare in a child and a mature cystic teratoma of the pancreas is even rarer. This is the first demonstration of the CT appearance of such a tumour in a child. We present a 2-year-old boy who presented with a palpable abdominal mass. Abdominal CT revealed a huge cystic mass in the upper abdomen. Pathology disclosed a mature cystic teratoma originating from the pancreas.

Biopsy↗

PubMed2003

Dysphagia in patients with nasopharyngeal cancer after radiation therapy: a videofluoroscopic swallowing study.

This study evaluated swallowing status and the factors influencing swallowing in patients with nasopharyngeal carcinoma (NPC) after radiation therapy. During the period from July 1995 to June 1999, this cross-sectional study used videofluoroscopic swallowing study (VFSS) to evaluate 184 NPC patients who had completed radiation therapy [113 cases had completed radiation therapy < or = 12 months prior to evaluation (acute group) and 71 cases had completed radiation therapy > 12 months prior to evaluation (chronic group)]. The numbers of patients with tumors in each of the four stages were as follows: 24 in stage I, 45 in stage II, 41 in stage III, and 74 in stage IV. Swallowing abnormalities of the acute and chronic groups were correlated with multiple variables, including gender, age, the stage of the tumor, use of either neoadjuvant chemotherapy or radiosensitizer, and radiation modality. The analytical results indicated that the chronic group had a significantly higher proportion of swallowing abnormalities. Radiation modality, chemotherapy, and tumor staging were not significantly associated with swallowing dysfunction. Trend analysis revealed a progressive deterioration of most parameters of swallowing function in this group of patients. These findings indicate that swallowing function continues to deteriorate over time, even many years after radiation therapy in patients with NPC. Our results indicate that the time elapsed since radiation therapy correlates with the severity of dysphagia in NPC patients.

Adolescent↗

PubMed2002

Mesenteric lipoblastoma: case report.

We present a rare case of mesenteric lipoblastoma in a 16-month-old girl. The US, CT and MRI features of this unusual tumour are described and correlated with the pathology findings. MRI more clearly suggested the presence of fat components in the tumour. In addition, multiplanar MR images demonstrated the anatomical extent better, which was essential for successful complete tumour excision.

Female↗

PubMed2002

Radiological features of late-onset lymphoedema in Noonan's syndrome.

Noonan's syndrome is a multiple congenital anomaly syndrome with diverse manifestations. Lymphatic abnormalities occur in less than 20% of patients. We report a 14-year-old boy who presented with swollen lower limbs and dysmorphic features characteristic of Noonan's syndrome. The radiological features of this unusual case of late-onset lymphoedema in association with Noonan's syndrome are presented.

Adolescent↗

PubMed2002

Silicone migration from silicone-injected breasts: magnetic resonance images.

Injection of liquid silicone into the breast was performed illicitly in the 1950s to 1960s and was subsequently prohibited. Many complications arise from silicone injection, and liquid silicone migration is a complication that has not been widely reported. The authors present magnetic resonance images of a patient with liquid silicone migration from the breast to the upper chest and lower neck. Breast ultrasonographic and mammographic findings are also presented for correlation.

Adult↗

PubMed2002

Adrenal gland volume after spinal cord injury.

OBJECTIVE: Spinal cord injury in adult men may result in hypothalamic-pituitary-adrenal axis dysfunction. Atrophy of adrenal glands was speculated in these patients. This study was undertaken to clarify the functional-anatomic correlation between adrenal volume and body surface area in subjects with spinal cord injury with impaired adrenal reserve. DESIGN: Twenty male subjects with chronic spinal cord injury with impaired adrenal reserve were identified by adrenocorticotropic hormone stimulation test from a group of 42 subjects. All subjects with spinal cord injury and healthy volunteers underwent computed tomographic imaging with contiguous 3-mm section over adrenal glands for volumetric measurements. Ten pairs of subjects with spinal cord injury and controls with matched height and weight were included in the statistical analysis. RESULTS: Significantly increased relative adrenal volumes were noted among subjects with chronic spinal cord injury and impaired adrenal reserve as compared with the body weight-matched and height-matched control group. CONCLUSIONS: Increased relative adrenal volumes were found after chronic spinal cord injury. Hyperplasia of the zona glomerulosa may be the cause of increased relative adrenal volume after chronic spinal cord injury.

Adrenal Glands↗

PubMed2002

Magnetic resonance imaging characteristics of paraffinomas and siliconomas after mammoplasty.

BACKGROUND AND PURPOSE: Breast paraffinomas and siliconomas are granulomas caused by tissue reaction to paraffin oil and silicone injection after mammoplasty. These granulomas usually present as multiple hard masses that mimic breast cancer. Mammography and sonography have only a limited role in differentiating these masses. Magnetic resonance (MR) imaging findings of these granulomas have rarely been reported. This study evaluated the MR imaging manifestations of these granulomas. MATERIALS AND METHODS: MR imaging, mammography, and sonography were used to examine 58 breasts in 29 women with breast lumps who had undergone mammoplasty with injections of paraffin oil (n = 8) or liquid silicone (n = 50). The protocol included T1-weighted images (T1WI), fat-suppressed (FS) T2WI, post-contrast FS three-dimensional fast dynamic sequences, and FS T1WI. RESULTS: Deep structures of the 58 breasts could not be clearly evaluated by sonography or mammography. Two types of MR imaging characteristics were identified: type I lesions were hypointense on T2WI and type II lesions had mixed hypointense and hyperintense components on T2WI. Both showed intermediate intensity on T1WI and revealed no enhancement on post-contrast dynamic sequences and FS T1WI. Type II lesions were seen only in siliconomas. Mastectomy was performed on seven breasts and paraffinomas or siliconomas were confirmed by pathology. When correlating MR images with pathology, hypointense lesions on T2WI in both type I and II lesions were foreign body granulomas with fibrosis and calcification. Hyperintense lesions on T2WI in type II were liquid silicone. A case of infiltrating ductal carcinoma was found in one breast in which MR imaging was successful in identifying the strongly enhanced solitary tumor from a background of type I lesions of paraffinomas preoperatively. Of the 51 breasts that did not receive surgery, no breast cancers were detected clinically or by follow-up imaging after a median of 27 months (19-54 mo). CONCLUSIONS: Breast paraffinomas and siliconomas after mammoplasty have specific MR findings that are distinct from those of breast cancers. MR imaging is superior to sonography and mammography in the evaluation of breast paraffinomas and siliconomas.

Adult↗

PubMed2002

Clinical characteristics and management of acute suppurative thyroiditis in children.

BACKGROUND: Acute suppurative thyroiditis is an uncommon disease in children. This paper describes the clinical characteristics and management of children with acute suppurative thyroiditis treated during a 15-year period at National Taiwan University Hospital. PATIENTS AND METHODS: From 1985 to 2000, acute suppurative thyroiditis was diagnosed in 11 previously healthy children (6 boys, 5 girls) at the Department of Pediatrics. Their mean age at diagnosis was 6.4 +/- 4.4 years. Leukocyte count, acute-phase reactants, thyroid function, and thyroid autoantibodies were assessed. Samples were taken by thyroid needle aspiration for cytology study and pus culture. Underlying pyriform sinus fistula (PSF) was demonstrated by barium esophagogram. RESULTS: Leukocytosis was noted in six cases (55%) and acute-phase reactants were elevated in eight cases (73%). Neither thyroid autoantibodies nor thyroid dysfunction was detected in any of the patients. Barium esophagogram detected PSF in eight of 10 patients examined. Five (45%) patients had recurrent suppurative thyroiditis before surgery. Cytology and pus cultures were available for 10 patients. Polymorphonuclear cells were the main findings in the smear from thyroid aspirates. Twenty-two organisms were isolated from six patients (60%). Streptococcus species (45%) and anaerobic organisms (41%) were the most common pathogens isolated. Mixed infection was detected in five of six children who had a causative microorganism identified. The microorganisms were all sensitive to amoxicillin-clavulanate. CONCLUSION: PSF plays a role in the pathogenesis of acute suppurative thyroiditis in children. Streptococcus species are the most common pathogens in acute suppurative thyroiditis. Our results suggest that amoxicillin-clavulanate is the drug of choice for the treatment of this disease.

Acute Disease↗

PubMedDate not supplied

Lymphangioleiomyomatosis initially presenting with abdominal pain: a case report.

Lymphangioleiomyomatosis (LAM) is a rare idiopathic disease characterized by hamartomatous smooth muscle proliferation of the lymph node, lymphatics, blood vessels as well as airways within the lungs, mediastinum and abdomen. It exclusively affects women during the reproductive period. Though extrapulmonary manifestations have been reported, the initial presentation of LAM as abdominal pain is extremely rare. To our knowledge, there are only three cases with LAM presenting first with abdominal symptoms so far [Chest 106 (1994) 267; Eur J Radiol 14 (1992) 192; Eur J Surg 157 (1991) 36]. We describe a case of LAM suffering from abdominal pain followed by pulmonary symptoms and the diagnosis was not made until pathohistological examination.

Abdominal Neoplasms↗

PubMedDate not supplied

Diffusion-weighted images in children with meningoencephalitis.

PURPOSE: The objective of the study was to evaluate the maps of apparent diffusion coefficients (ADCs) and diffusion-weighted (DW) images in demonstrating meningoencephalitic lesions in children. MATERIALS AND METHODS: Between May 1998 and May 2000, 18 infants and children (4.5-190 months old) suffering from meningoencephalitis were included in the study. The diagnoses were bacterial meningoencephalitis in 8 and aseptic or viral in 10 patients. All 18 patients had brain MRI examinations. In the axial plane, three pulse sequences were performed on all patients: (1) FSE T2W images; (2) fast FLAIR images; (3) single-shot echoplanar DW images were acquired. Another 18 patients from the control group also received DW image examination. ADCs were computed for all regions on each DW image. RESULTS: The absolute values of CNRs of lesions on T2W (7.27+/-5.51), FLAIR (5.56+/-5.03) and DW (13.36+/-16.64) images were significantly greater than those on ADC maps (0.42+/-0.30) in the study group of patients (P<.01). In addition, absolute CNRs on DW images were significantly greater than on T2W and FLAIR images (P<.01). However, lesions on ADC maps in the study group have significantly greater CNRs than in the control group (0.13+/-0.12) (P<.01). CNRs on initial DW images from patients with atrophy or swelling of meningoencephalitic lesions were significantly different from the CNRs of those patients without significant changes in meningoencephalitic lesions (P=.02<.05). CONCLUSION: The DW image is a sensitive tool for detecting meningoencephalitic lesions and is better than FSE T2W and fast FLAIR images in CNRs. Diffusion MR techniques provides new ways to possibly predict the outcome of intracranial infectious diseases in children.

Brain Mapping↗

PubMedDate not supplied

Unusual manifestations of soft tissue metastasis.

We present a patient with pulmonary adenocarcinoma metastatic to the left forearm. The magnetic resonance imaging (MRI) revealed no discrete tumor, but an infiltrative signal change of the subcutaneous tissue and muscle. The lymphatic invasion by cancer cells explains this unusual manifestation of image findings.

Adenocarcinoma↗