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W Y Tseng

Publications and source records attributed to W Y Tseng.

6 recordsLinked to original sources
PubMed1999

Cardiac diffusion tensor MRI in vivo without strain correction.

Cardiac diffusion MRI with diffusion encoding that spans a cardiac cycle is complicated by myocardial strains. This paper presents a method to obtain accurate diffusion data without strain correction. Owing to the synchrony of normal cardiac motion, there are time points in the cardiac cycle, "sweet spots," when the cardiac configuration approximates its temporal mean. If the diffusion is encoded then, the net effect of strain on the observed diffusion approximates zero. To test this, MRI diffusion and strain-rate movies are performed on cyclically deformed gel phantoms and in five normal subjects. In phantoms, the sweet spots predicted from the strain time curves agree with the times when the observed diffusion equals the true diffusion. In humans, the strain prediction of the sweet spots and the locations determined by the diffusion trace show a high correlation, r = 0.99. In all subjects, diffusion MRI presents a fiber orientation pattern comparable to that obtained from a stationary specimen. Magn Reson Med 42:393-403, 1999.

Adult↗
PubMed1997

NMR study of solid C60(gamma-cyclodextrin)2.

A solid complex of C60 with gamma-cyclodextrin (gamma-CyD) was examined with NMR spectroscopic methods in order to understand the dynamics of C60, and the interaction between C60 and gamma-CyD. A 13C solid-state cross-polarization magic angle spinning (CP/MAS) NMR spectra shows C60 resonance at 142.6 ppm. This provides the evidence of interaction between 13C spins in C60 and 1H spins in the gamma-CyD host. Ambient temperature experiments on the 13C CP/MAS NMR, with varying contact time, shows that the water associated with gamma-CyDs plays an important role in the nuclear relaxation processes. The dynamics of C60 in gamma-CyD was investigated using temperature and field-dependent 13C spin-lattice relaxation time measurements. The influence of water on the dynamics of C60 was less significant below 250 K.

Carbon↗
PubMed1992

Multiplanar gradient recalled images of the knee: comparison of different flip angles and echo times.

To determine the most appropriate combination of echo time (TE) and flip angle in gradient echo images of the knee, the authors used different TEs (10, 20 and 30 msec) and flip angles (10, 30, 50, 70, 90, 120 and 150 degrees) to perform a systematic study of MRI on 10 volunteer knees. Contrast-to-noise ratios of cartilage-fat, fluid-cartilage, fluid-fat and fluid-ligament were calculated and compared. Images with a 30-degree flip angle combined with 20 msec of TE were found to have the best contrast-to-noise ratios in both objective data analysis and subjective observation. Hyaline cartilage of the knee was hyperintense and was well delineated on this pulse sequence, appearing distinct in contrast to the intra-articular fluid. It is concluded that this T2-weighted gradient echo pulse sequence is an alternative to conventional spin echo T2-weighted imaging of the knee.

Echo-Planar Imaging↗
PubMed1991

Burkitt's and non-Burkitt's type lymphoma: clinicopathological and radiological manifestations.

Nine cases of Burkitt's type and 5 case of non-Burkitt's type small, non-cleaved cell lymphoma were retrospectively studied to evaluate their clinical and radiological manifestations. In the Burkitt's group, the median age of onset was 9 years old; the male to female ratio was 2:1; and the most frequent presentation was abdominal mass. These features conformed to those of non-endemic (or American) type Burkitt's lymphoma. In comparison with the Burkitt's group, less male-predominance (M:F = 2:3) and cervical mass as the most frequent initial symptom were found in the non-Burkitt's group. Plain films and computed tomographies were collected to evaluate the encroachment of the disease into various organs or compartments. There was a statistically significant correlation in site of the main mass between these two types; the Burkitt's type prefers extranodal, whereas the non-Burkitt's type prefers nodal, involvement. Computed tomographic appearance of Burkitt's lymphoma was also analyzed and summarized by the following five aspects: (1) tumor location-predominantly in the abdomen or head/neck region; (2) tumor density-rather homogeneous and slightly less than that of muscle; (3) tumor margin-often well-localized with distinct contrast to adjacent normal tissue; (4) extranodal predilection- the most frequent pattern of involvement; and (5) bony chang-often mild, despite the size of the mass.

Adolescent↗
PubMed1991

Solid and papillary neoplasm of the pancreas: report of three cases.

We report 3 cases of solid and papillary neoplasm of the pancreas, which is a rare pancreatic tumor with distinct clinicopathologic characteristics. Sonographic, computed tomographic (CT) and gross pathologic findings of these 3 patients were obtained and compared. The tumors had a smooth, enhanced capsule and variable internal architecture. Two of the tumors appeared to be of the heterogeneous soft tissue density type, while one of the tumors was of the mixed solid and cystic type. Because the CT appearance of this tumor is subject to variation, it should be differentiated from other pancreatic lesions with variable CT appearances. Several CT features such as soft tissue density of the mass in a precontrast study, a well-enhanced capsule and the absence of pancreatic or biliary duct dilatation, as well as the characteristic young-female predilection, may aid in a correct diagnosis before surgery.

Adolescent↗