Biomedical subjects

Chin A Yi

Publications and source records attributed to Chin A Yi.

8 recordsLinked to original sources

PubMed2003

Imaging-guided percutaneous radiofrequency ablation of pulmonary metastatic nodules caused by hepatocellular carcinoma: preliminary experience.

OBJECTIVE: The purpose of our study was to evaluate the efficacy of imaging-guided percutaneous radiofrequency ablation of metastatic pulmonary nodules caused by hepatocellular carcinoma. CONCLUSION: Percutaneous radiofrequency ablation is feasible and can be a promising method for the local control of metastatic pulmonary nodules caused by hepatocellular carcinoma, especially when they are limited in number.

Adult↗

PubMed2003

Multidetector CT of bronchiectasis: effect of radiation dose on image quality.

OBJECTIVE: The purpose of our prospective study was to assess the image quality with respect to the radiation dose incurred by multidetector CT (MDCT) in patients with suspected bronchiectasis. SUBJECTS AND METHODS. Image clusters, composed of nine images, using MDCT (120 kVp, a 2.5-mm collimation, a pitch of 6, and 2.5-mm reconstruction intervals) were obtained at each of two levels-the azygous arch and the right inferior pulmonary vein-at 170, 100, 70, 40, 20, and 10 mA. Independently, two chest radiologists assessed and compared the quality of the images obtained at the six milliamperage exposures. Image quality was graded using a 5-point scale with lung and mediastinal window settings. Radiation doses were measured at each of the six milliamperage settings while scanning the whole lung of a thoracic phantom using MDCT. RESULTS: The mean image quality scores at exposures of 170, 100, 70, 40, 20, 10 mA were as follows: 3.9, 3.7, 3.8, 3.2, 2.5, 1.6 at lung window settings and 4.1, 4.3, 4.0, 3.4, 2.3, 1.3 at mediastinal window settings, respectively. Images obtained at 70 mA were rated significantly better than those obtained at 40 mA or less (p < 0.01). The mean radiation dose at 170, 100, 70, 40, 20, 10 mA was 23.72, 14.39, 10.54, 5.41, 2.74, and 1.50 mGy, respectively. CONCLUSION: With a tube current setting as low as 70 mA, MDCT provides images of acceptable quality and volumetric data sets for the evaluation of bronchiectasis. The trade-off of using MDCT rather than conventional high-resolution CT is that the radiation dose is five times higher with MDCT (10.54 mGy) than with conventional high-resolution CT (2.17 mGy with parameters of 120 kVp, 170 mA, 1-mm collimation, and 10-mm intervals).

Adult↗

PubMed2003

Radiographic and CT findings of nontuberculous mycobacterial pulmonary infection caused by Mycobacterium abscessus.

OBJECTIVE: The purpose of our study was to describe the radiographic and CT findings in patients with pulmonary infections caused by Mycobacterium abscessus, one of the more common rapidly growing nontuberculous mycobacteria that cause lung disease. CONCLUSION: The main radiologic and CT manifestations of M. abscessus lung infection are bilateral small nodular opacities, bronchiectasis, and cavity formation.

Adult↗

PubMedDate not supplied

Multiphasic perfusion computed tomography in hyperacute ischemic stroke: comparison with diffusion and perfusion magnetic resonance imaging.

PURPOSE: The purpose of this study was to compare multiphasic perfusion computed tomography (CT) with diffusion and perfusion magnetic resonance imaging (MRI) in predicting final infarct volume, infarct growth, and clinical severity in patients with hyperacute ischemia untreated by thrombolytic therapy. METHOD: Multiphasic perfusion CT was performed in 19 patients with ischemic stroke within 6 hours of symptom onset. Two CT maps of peak and total perfusion were generated from CT data. Diffusion-weighted imaging (DWI) and perfusion MRI were obtained within 150 minutes after CT. Lesion volumes on CT and MRI were compared with final infarct volume and clinical scores, and mismatch on CT or MRI was compared with infarct growth. RESULTS: The lesion volume on the CT total perfusion map strongly correlated with MRI relative cerebral blood volume (rCBV), and that on the CT peak perfusion map strongly correlated with MRI relative cerebral blood flow (rCBF) and rCBV (P < 0.001). The lesion volume on unenhanced CT or DWI moderately correlated with final infarct volume, but only lesion volume on unenhanced CT weakly correlated with baseline clinical scores (P = 0.024). The lesion volumes on the CT peak perfusion map and MRI rCBF similarly correlated with final infarct volume and clinical scores and more strongly than those on mean transit time (MTT) or time to peak (TTP). DWI-rCBF or CT mismatch was more predictive of infarct growth than DWI-MTT or DWI-TTP mismatch. CONCLUSION: Multiphasic perfusion CT is useful and of comparable utility to diffusion and perfusion MRI for predicting final infarct volume, infarct growth, and clinical severity in acute ischemic stroke.

Acute Disease↗

PubMedDate not supplied

Additional coronal images using low-milliamperage multidetector-row computed tomography: effectiveness in the diagnosis of bronchiectasis.

PURPOSE: The aim of our study was to evaluate the effectiveness of additional coronal images using low-milliamperage multidetector-row computed tomography (CT) in the diagnosis of bronchiectasis. METHODS: Helical volumetric CT scans (120 kVp, 70 mA, 2.5-mm collimation, table speed of 15 mm/s, table rotation time of 1 second) using low-milliamperage multidetector-row CT were obtained through the thorax in 110 patients who were suspected of bronchiectasis. Both axial (2.5-mm section thickness) and coronal (1.3-2.0-mm section thickness) reformatted images were made and sent to picture archiving and communication system (PACS) monitors. Two independent observers assessed CT scans twice; with axial images only and with both axial and coronal images. The detection rates of bronchiectasis were compared between readings with axial images only and with both axial and coronal images by using a nonparametric method of clustered data. Confidence grades were given to the distribution and type of bronchiectasis. RESULTS: With axial images only, the detection rates of bronchiectasis on a per-patient basis were 97% (213/220 patients, kappa = 0.888) whereas with both axial and coronal images, the detection rates were 100% (220/220 patients, kappa = 1.000) (P = 0.0001). Confidence to the distribution of bronchiectasis was greater with both axial and coronal images than with axial images only (P = 0.008). CONCLUSIONS: Additional coronal images using low-milliamperage multidetector-row CT are effective in the diagnosis of bronchiectasis by providing enhanced detection rates and confidence to the distribution of lesions.

Adult↗

PubMedDate not supplied

Radiological spectrum of intraductal papillary tumors of the bile ducts.

Papillary tumor of the bile duct is characterized by the presence of an intraductal tumor with a papillary surface comprising innumerable frondlike infoldings of proliferated columnar epithelial cells surrounding slender fibrovascular stalks. There may be multiple tumors along the bile ducts (papillomatosis or papillary carcinomatosis), which are dilated due to obstruction by a tumor per se, by sloughed tumor debris, or by excessive mucin. Radiologically, the biliary tree is diffusely dilated, either in a lobar or segmental fashion, or aneurysmally, depending on the location of the tumor, the debris, and the amount of mucin production. A tumor can be depicted by imaging as an intraductal mass with a thickened and irregular bile duct wall. Sloughed tumor debris and mucin plugs should be differentiated from bile duct stones. Cystically or aneurysmally, dilated bile ducts in mucin-hypersecreting variants (intraductal papillary mucinous tumors) should be differentiated from cystadenoma, cystadenocarcinoma and liver abscess.

Bile Duct Neoplasms↗

PubMedDate not supplied

Multiphasic perfusion CT in acute middle cerebral artery ischemic stroke: prediction of final infarct volume and correlation with clinical outcome.

OBJECTIVE: To assess the utility of multiphasic perfusion CT in the prediction of final infarct volume, and the relationship between lesion volume revealed by CT imaging and clinical outcome in acute ischemic stroke patients who have not undergone thrombolytic therapy. MATERIALS AND METHODS: Thirty-five patients underwent multiphasic perfusion CT within six hours of stroke onset. After baseline unenhanced helical CT scanning, contrast-enhanced CT scans were obtained 20, 34, 48, and 62 secs after the injection of 90 mL contrast medium at a rate of 3 mL/sec. CT peak and total perfusion maps were obtained from serial CT images, and the initial lesion volumes revealed by CT were compared with final infarct volumes and clinical scores. RESULTS: Overall, the lesion volumes seen on CT peak perfusion maps correlated most strongly with final infarct volumes (R(2)=0.819, p<0.001, slope of regression line=1.016), but individual data showed that they were less than final infarct volume in 31.4% of patients. In those who showed early clinical improvement (n=6), final infarct volume tended to be overestimated by CT peak perfusion mapping and only on total perfusion maps was there significant correlation between lesion volume and final infarct volume (R(2)=0.854, p=0.008). The lesion volumes depicted by CT maps showed moderate correlation with baseline clinical scores and clinical outcomes (R=0.445-0.706, p< or = 0.007). CONCLUSION: CT peak perfusion maps demonstrate strong correlation between lesion volume and final infarct volume, and accurately predict final infarct volume in about two-thirds of the 35 patients. The lesion volume seen on CT maps shows moderate correlation with clinical outcome.

Acute Disease↗

PubMedDate not supplied

Thymic epithelial tumors classified according to a newly established WHO scheme: CT and MR findings.

Thymic epithelial tumor is a distinctive pathologic entity exhibiting variable histologic features and heterogeneous oncologic behavior. Among the various classification systems, that of the World Health Organization has been adopted because of good correlation between histologic appearance and oncologic behavior. Radiologically, a smooth contour and round shape are most suggestive of a type-A tumor, whereas an irregular contour most strongly suggests type C. Pleural seeding is rare in type-A and AB tumors; calcification is suggestive of type B. Type-C tumors are significantly larger and more commonly associated with lymphadenopathy than type B3. At T2-weighted MR imaging, lobular internal architecture is more prominent in types B1, B2, and B3 tumors than in others. However, imaging findings among the various types overlap to some extent, and the ability of imaging studies to differentiate types AB, B1, B2, and B3 is limited.

Adult↗