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Biomedical subjects

Yi-Hong Chou

Publications and source records attributed to Yi-Hong Chou.

At least 19 recordsLinked to original sources
PubMed2007

Primary small cell carcinoma of the pancreas with an unusual sonographic appearance.

We present a case of primary pancreatic small cell carcinoma with an unusual sonographic feature. A 75-year-old woman presented with poor appetite and weight loss. Abdominal sonographic examination revealed a diffusely enlarged pancreas with relative increased echogenicity and smooth contour. CT also confirmed the diffuse infiltrative pattern of the tumor. The diagnosis was confirmed via sonographically guided biopsy. The tumor was composed of small cells with hyperchromatic nuclei and scanty cytoplasm infiltrating the pancreatic tissue, consistent with small cell carcinoma of the pancreas. Primary pancreatic small cell carcinoma rarely presents as the diffuse infiltrating type. These unusual sonographic features must be differentiated from other pancreatic tumors presenting as diffuse pancreatic enlargement.

Aged↗
PubMed2006

Determining the significance of coagulase-negative staphylococci identified in cultures of paired blood specimens from neonates by species identification and strain clonality.

Of 13 paired coagulase-negative staphylococci (CoNS) isolates recovered from cultures of paired blood specimens obtained simultaneously from peripheral sites from neonates with clinical sepsis, 12 were identical species with identical genotypes. Isolation of CoNS in cultures of 2 blood samples obtained simultaneously from separate sites in neonates usually represents true infection.

Bacteremia↗
PubMed2006

An improved spectral width Doppler method for estimating Doppler angles in flows with existence of velocity gradients.

Doppler angle (i.e., beam-to-flow angle) is an important parameter for quantitative flow measurements. With known Doppler angles, volumetric flows can be obtained by the mean flow velocity times the cross-section area of the vessel. The differences or changes between prestenotic and poststenotic volumetric flows have been quantified as an indicator for assessing the clinical severity of the stenosis. Therefore, several research groups have dedicated themselves to developing user-independent methods to determine automatically the Doppler angle. Nevertheless, most of these methods were developed for narrow ultrasound beam measurements. For small vessels, where the beam width is a significant fraction of the diameter of the vessel, the effect of velocity gradients plays an important role and should not be ignored in the Doppler angle estimations. Accordingly, this paper is concerned with a method for improving the estimation of Doppler angles from spectral width Doppler (SWD) method, but correcting for velocity-gradient broadening that may arise when the beam has a nonzero width. In our method, Doppler angles were firstly calculated by SWD and then were corrected by an artificial neural network (ANN) method to neutralize the contribution of velocity gradient broadening (VGB). This SWD and ANN conjoint method has been successfully applied to estimate Doppler angles from 50 degrees to 80 degrees for constant flows in 10 mm, 4 mm and 1 mm diameter tubes, whose mean flow velocities were 15.3, 19.9 and 25.5 cm/s, respectively, and the achieved mean absolute errors of the estimated Doppler angles were 1.46 degrees , 1.01 degrees and 1.3 degrees.

Blood Flow Velocity↗
PubMed2006

Superficial soft-tissue lymphoma: sonographic appearance and early survival.

We evaluated superficial soft-tissue lymphomas on high-resolution ultrasonography (HRUS) in 43 patients (17 women, 26 men; mean, 59.7 y; range, 12 to 90 y), with 1- to 97-month follow-up. Clinical presentations, tumor location and morphology, echogenicity on HRUS and color-encoding grades on Doppler ultrasonography (CDUS) were assessed. Clinical presentations did not significantly differ with tumor location or morphology. Types of lymphoma did not significantly differ in echogenicity, although most were hypoechogenic. On CDUS, most lymphomas were hypervascular, but grades did not significantly depend on the type of tumor. On Kaplan-Meier analysis with log-rank testing, survival did not differ by age (divided at 65 y), sex, tumor location or size (cut-off, 5 cm), CDUS grade or pathology. Survival was significantly related to clinical presentation (p < 0.0095) and tumor morphology (p < 0.0354). HRUS and CDUS were good modalities to detect the masses and provided important pretreatment information.

Adolescent↗
PubMed2006

Sonographic features of nonpalpable breast cancer: a study based on ultrasound-guided wire-localized surgical biopsies.

The purpose of this study is to investigate the correlation between surgicopathological findings and ultrasonic images of nonpalpable breast lesions. The study was composed of 220 nonpalpable breast lesions from 193 patients. The breast lesions were classified into soft tissue type (185 lesions) and calcification type (35 lesions). Of the 220 lesions, 62 (28%) were malignant. For soft tissue type lesions, the sonographic features of sound attenuation (p < 0.001) and irregular border (p < 0.001) were significantly associated with the malignant diagnosis. For soft tissue-type and calcification-type lesions, the presence of increased vascularity (p < 0.001) or calcification (p < 0.001) was significantly associated with the malignant diagnosis. Of the 164 breast lesions with corresponding mammograms, 37 of 74 mammographically identifiable lesions were pathologically malignant, as compared with 16 of 90 lesions with negative mammograms (p < 0.001). In our study, the more sensitive sonographic features for predicting malignancy were irregular border and increased vascularity (sensitivity 88% and 82%, respectively), whereas the features of sound attenuation and presence of calcifications were more specific (specificity 88% and 80%, respectively). In conclusion, ultrasound-guided wire localization of breast lesions is not only useful in assisting surgical biopsy, but the sonographic findings obtained by this procedure correlate with pathologic diagnosis.

Adolescent↗
PubMed2006

Imaging findings in mucin-producing carcinoma of the gallbladder.

Mucin-producing carcinoma of the gallbladder is rare, and its imaging features have not been well documented. Its symptoms and signs are nonspecific and the prognosis of the disease is poor. We present a 73-year-old male with mucin-producing carcinoma of the gallbladder, emphasizing its imaging features on ultrasound, computed tomography and magnetic resonance imaging. The tumor usually presents as a cauliflower-like soft tissue mass with small calcified spots in the gallbladder wall and some laminated high viscosity fluid inside the gallbladder cavity. Recognition of these features can provide clues to the diagnosis of mucin-producing carcinoma of the gallbladder.

Adenocarcinoma, Mucinous↗
PubMed2006

Significance of coagulase-negative staphylococci isolated from a single blood culture from neonates in intensive care.

BACKGROUND: Coagulase-negative staphylococci (CoNS) are the most common pathogens of late-onset bacteraemia in neonatal intensive care units (NICUs). Discriminating true infection from contamination is difficult. METHODS: To evaluate the significance of a single blood culture yielding CoNS from only one blood culture obtained from NICU infants between July 1999 and November 2000, paired blood cultures were obtained simultaneously from two peripheral sites from infants hospitalised in two NICUs with clinically suspected late-onset sepsis, and a single blood culture was obtained peripherally from infants hospitalised in a third NICU. Demographic data, predisposing factors, clinical manifestations, laboratory data, management and outcome of infants with either paired or single blood cultures yielding CoNS were analysed and compared. RESULTS: Both blood cultures yielded CoNS during 26 episodes in 24 infants. A single blood culture which grew CoNS from one blood culture was identified during 24 episodes in 23 infants. Except for prior use of an umbilical venous catheter, there was no significant difference between the infants with CoNS isolated from a paired or a single blood culture in terms of demographic characteristics, predisposing factors, clinical manifestations, laboratory findings, management and outcome. CONCLUSION: There was no difference in the clinical features of CoNS infection between single and paired CoNS-positive blood cultures.

Bacteremia↗
PubMed2006

Methicillin-resistant Staphylococcus aureus colonization and its association with infection among infants hospitalized in neonatal intensive care units.

OBJECTIVES: We conducted this study to assess the rate of methicillin-resistant Staphylococcus aureus colonization and its association with infection among infants hospitalized in methicillin-resistant S aureus-endemic NICUs. METHODS: Between March 2003 and February 2004, surveillance culture specimens from the nares, postauricular areas, axillae, and umbilicus of infants admitted to the NICUs at a children's hospital in Taiwan were obtained weekly for the detection of methicillin-resistant S aureus. All colonized and clinical isolates from each study infant with methicillin-resistant S aureus infection were genotyped with pulsed-field gel electrophoresis, with Sma1 digestion, and compared. RESULTS: A total of 783 infants were included in this study. Methicillin-resistant S aureus colonization was detected for 323 infants during their NICU stays, with detection with the first 2 samples for 89%. Nares and umbilicus were the 2 most common sites of initial colonization. Methicillin-resistant S aureus colonization was associated significantly with premature birth (< or = 28 weeks) and low birth weight (< or = 1500 g), and infants with colonization had a significantly higher rate of methicillin-resistant S aureus infection, compared with those without colonization (26% vs 2%). Methicillin-resistant S aureus colonization was noted for 84 of 92 infants with methicillin-resistant S aureus infections. Of the 68 episodes with previous colonization and isolates available for genotyping analysis, colonized and clinical isolates were indistinguishable in 63 episodes, highly related in 2 episodes, and distinct in 3 episodes. CONCLUSIONS: More than 40% of the hospitalized infants were colonized with methicillin-resistant S aureus during their stay in methicillin-resistant S aureus-endemic NICUs; this was associated significantly with methicillin-resistant S aureus infection. Most infants with methicillin-resistant S aureus infections had previous colonization with an indistinguishable strain.

Axilla↗
PubMed2005

Can ruptured appendicitis be detected preoperatively in the ED?

PURPOSE: The purpose of this study is to determine which clinical symptoms/signs and computed tomography (CT) signs can help in distinguishing ruptured from simple appendicitis. MATERIALS AND METHODS: The medical records and CT findings of 202 consecutive patients with surgically proven acute appendicitis were retrospectively reviewed and compared between 2 groups with and without appendiceal rupture. RESULTS: Longer duration of symptoms ( P < .001), peritoneal sign ( P = .004), and higher C-reactive protein ( P < .001) are significant clinical factors for predicting appendiceal rupture in acute appendicitis. Abscess, extraluminal air, wall defect, peritoneal enhancement, extraluminal appendolith, phlegmon, localized fluid, fascial thickening, ascites, stool impaction, and 4 patterns of bowel wall thickening ( P < .001 to P = .047) are significant CT signs for predicting appendiceal rupture. The appendiceal diameter is larger in patients with ruptured appendicitis than in those with simple appendicitis (13.2 +/- 3.2 vs 11.3 +/- 2.4 mm, P < .001). The appendolith size is larger in patients with ruptured appendicitis than in those with simple appendicitis (7.1 +/- 4.4 vs 5.1 +/- 2.8 mm, P = .018). CONCLUSION: Besides some clinical findings, CT scan can accurately determine appendiceal rupture in acute appendicitis and can further demonstrate the presence of local inflammatory mass, facilitating management decision in the emergency department (ED).

Adolescent↗
PubMed2005

An ultrasonic microbubble semi-intermodulated imaging technique.

The performance of contrast imaging technique is critically influenced by some factors, such as spatial resolution, agent-to-tissue ratio, lifetime of contrast agents and attenuation effect. By using a transducer with higher frequency and higher bandwidth of transmitted signals, the spatial resolution can be improved. Similarly, a better signal-to-interference ratio (SIR) can improve the agent-to-tissue ratio, a lower transmission pressure can prolong the lifetime of contrast agents and a lower center frequency can diminish the attenuation effect. We extend the two-frequency analytic solutions of to approximate the short-pulse responses of microbubbles in a low-amplitude field. Based on their results, there is an expected component near 0 Hz in the spectrum of bubble echoes excited by a short pulse of ultrasound. Here, this component is called the low-frequency response; and it is shown to have a special bandwidth-dependent property and to have potential applications in imaging. We have established the procedure of semi-intermodulated (low-frequency) imaging and the effects of the attenuation effect on imaging resolution, SIR, and signal-to-noise ratio are also analyzed. The obtained experimental images demonstrate that the SIR in semi-intermodulated imaging is better than that in fundamental imaging under various attenuation conditions.

Contrast Media↗
PubMed2005

Cell-competition algorithm: a new segmentation algorithm for multiple objects with irregular boundaries in ultrasound images.

Segmentation of multiple objects with irregular contours and surrounding sporadic spots is a common practice in ultrasound image analysis. A new region-based approach, called cell-competition algorithm, is proposed for simultaneous segmentation of multiple objects in a sonogram. The algorithm is composed of two essential ideas. One is simultaneous cell-based deformation of regions and the other is cell competition. The cells are generated by two-pass watershed transformations. The cell-competition algorithm has been validated with 13 synthetic images of different contrast-to-noise ratios and 71 breast sonograms. Three assessments have been carried out and the results show that the boundaries derived by the cell-competition algorithm are reasonably comparable to those delineated manually. Moreover, the cell-competition algorithm is robust to the variation of regions-of-interest and a range of thresholds required for the second-pass watershed transformation. The proposed algorithm is also shown to be superior to the region-competition algorithm for both types of images.

Algorithms↗
PubMed2005

Percutaneous ultrasound-guided radiofrequency ablation of intrahepatic cholangiocarcinoma.

This study evaluated the clinical applications, treatment effects, and complications of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) of intrahepatic cholangiocarcinoma. Ten patients (6 men and 4 women) with histologically proven cholangiocarcinoma underwent US-guided percutaneous RFA. Tumor diameters ranged from 1.9 to 6.8 cm. There were 12 sessions of RFA for 10 solitary cholangiocarcinomas. Eight patients were treated at a single session and two patients had two treatment sessions. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography 1 month after treatment and then every 3 months. Complete necrosis was defined as lack of contrast enhancement of the treated region. There was complete necrosis in eight tumors. In two patients with large tumors (4.7 and 6.8 cm in diameter), enhancement of residual tissue was observed after RFA treatment, indicating residual tumor. Complete necrosis was seen in all five tumors (100%) with diameters of 3.0 cm or less, two of three tumors (67%) with diameters of 3.1-5.0 cm, and one of two tumors (50%) with diameters of more than 5.0 cm. A large biloma was found in one patient after treatment. No serious complications occurred in the other nine patients. In conclusion, percutaneous RFA is effective and successful in the treatment of intrahepatic cholangiocarcinoma of 3 cm or less and satisfactory for tumors of 3-5 cm. The rate of serious complications after RFA is low. Further follow-up is necessary to determine long-term efficacy.

Adult↗
PubMed2005

Hydatid cyst of the liver: a case report and literature review.

Taiwan is nearly free from hydatid disease. We report a case of hydatid cyst of the liver in a 37-year-old man who originally lived in India and had migrated to Taiwan 2 years earlier. He presented with right upper quadrant pain and intermittent low-grade fever. Both sonography and computed tomography (CT) demonstrated a cystic lesion with vesicles at its periphery in segments 6 and 7 of the liver. A hydatid cyst was diagnosed. The patient underwent radical excision of the cyst with total removal without opening the wall. He also received pre- and postoperative oral mebendazole. Pathology showed a hydatid cyst consisting of three layers: the inner single nucleated geminal layer, the middle acellular laminated layer, and the outer pericyst originating from inflammatory and hepatic cells. This case highlights that accurate preoperative diagnosis of hydatid disease can be made from personal history, typical sonography and CT study in non-endemic areas.

Adult↗
PubMed2005

Internal hernia: computed tomography diagnosis and differentiation from adhesive small bowel obstruction.

BACKGROUND: The goals of this study were to evaluate the specific computed tomography (CT) features of internal hernia (IH), and to verify CT features useful for the differential diagnosis of IH from adhesive small bowel obstruction (ASBO), and for the early detection of intestinal strangulation. METHODS: CT findings for 28 patients with surgically proven IH were retrospectively reviewed and compared with those for 50 patients with surgically proven ASBO. RESULTS: CT features most suggestive of IH versus ASBO included the following: a cluster of small bowel segments (100% vs 4% of patients; p < 0.0001); crowding and convergence of mesenteric vessels (79% vs 4%; p < 0.0001); mesenteric vessel engorgement (79% vs 26%; p = 0.0002); and mass effect to the surrounding bowels (82% vs 44%; p = 0.002). In addition, intestinal strangulation, the most severe complication, occurred more in IH than ASBO (39% vs 10%; p = 0.002), whereas proximal small bowel dilation (46% vs 100%; p < 0.0001) and small-bowel feces sign (0% vs 26%; p = 0.0029) were less common in IH than ASBO. The CT features indicative of intestinal strangulation were localized mesenteric fluid (p < 0.0001), mesenteric infiltrates (p = 0.0005), bowel wall thickening (p = 0.003), intramural hemorrhage (p = 0.005), mesenteric vessel engorgement (p = 0.03), and abnormal bowel wall enhancement (p = 0.008); the first 4 of these features were noted more in patients with IH than ASBO. CONCLUSION: The most specific CT criteria for the diagnosis of IH, rather than ASBO, were engorged mesenteric vessels, mass effect to surrounding organs, and bowel wall thickening. When associated mesenteric infiltrates were found, intestinal strangulation was highly suspected.

Abdomen↗
PubMed2005

Differentiating colonic diverticulitis from colon cancer: the value of computed tomography in the emergency setting.

BACKGROUND: The purpose of this study was to establish practical diagnostic criteria to differentiate colonic diverticulitis from colon cancer by computed tomography (CT) in the emergency department (ER). METHODS: Helical CT scans of 40 patients admitted to the ER with the clinical diagnosis of diverticulitis and 14 patients diagnosed with colon cancer were retrospectively reviewed. In total, 18 imaging parameters were analyzed and were compared between the 2 groups of patients. RESULTS: Thirteen parameters were found to be statistically significant for the diagnosis of colonic diverticulitis in excluding colon cancer: pericolic infiltration (p < 0.001); presence of lymph nodes (p < 0.001); inflamed diverticula (p = 0.001); non-inflamed diverticula (p = 0.001); degree of enhancement (p = 0.001); intestinal obstruction (p = 0.001); involved wall thickness (p = 0.005); lymph node size (p = 0.007); fascial thickening (p = 0.009); pattern of enhancement (p = 0.012); involved length (p = 0.014); free air (p = 0.035); and abscess formation (p = 0.042). Among these parameters, the most valuable imaging findings for diverticulitis were the presence of non-inflamed diverticulum, inflamed diverticulum, mild degree of enhancement, and small lymph node size. Three were found to have high specificity but low sensitivity: target enhancement pattern; abscess formation; and free air. When colonic obstruction is present, colon cancer is more likely than diverticulitis. CONCLUSION: Specific CT criteria help to differentiate colonic diverticulitis from colon cancer. CT scan with intravenous contrast administration would be the best noninvasive imaging modality in the ER for the accurate diagnosis and appropriate management of such disease.

Adult↗
PubMed2005

Percutaneous radiofrequency ablation of renal cell carcinoma.

BACKGROUND: Preliminary data regarding the use of percutaneous radiofrequency ablation (RFA) for the treatment of renal cell carcinoma (RCC) are encouraging, and show the technique to be associated with minimal morbidity. Thus, the current study was designed to evaluate the clinical applications, treatment efficacy, and complications of percutaneous RFA in RCC. METHODS: From February 2003 to February 2004, 12 consecutive patients with histopathologically proven RCC underwent imaging-guided percutaneous RFA. The mean age of the patients (8 men and 4 women) was 76 years (range, 56-87 years), and mean tumor diameter was 3.7 cm (range, 2.2-8.0 cm). The efficacy of RFA was evaluated with contrast-enhanced, dynamic computed tomography (CT) performed 1 month after treatment, and then every 3 months. A Radionics device with an internally cooled electrode was used in 7 patients, and a radiofrequency interstitial tissue ablation (RITA) device with an expandable needle electrode was used in 5. Complete necrosis was defined as a lack of contrast enhancement in the treated region on follow-up CT studies. RESULTS: Overall, 16 sessions of RFA were performed for 12 solitary renal tumors in 12 patients: 8 patients underwent a single RFA session, whereas 4 had 2 sessions. Dynamic CT after RFA showed complete necrosis in 9 of 12 tumors. In 3 patients with tumors of 4.5-8.0 cm in diameter, enhancement of residual tissue was observed after RFA treatment, thus indicating residual tumor. Complete tumor necrosis was seen in all 5 tumors (100%) of diameter < or = 3.0 cm; 3 of 4 tumors (75%) of diameter 3.1-5.0 cm; and 1 of 3 tumors (33%) of diameter > 5.0 cm. A big subcapsular hematoma, which was found in 1 patient after RFA, resolved completely within 10 months without treatment; no serious complications occurred in the other 11 patients. CONCLUSION: Percutaneous RFA is effective in the treatment of RCC. It is most successful for tumors not larger than 3 cm in diameter, and has a satisfactory success rate in tumors of 3-5 cm in diameter. The rate of serious complications of RFA is low. Further studies are necessary to determine the long-term efficacy of RFA in RCC.

Aged↗
PubMed2005

Premature rupture of the membranes: a cause for neonatal osteomyelitis?

Osteomyelitis is rare in the neonatal period. Many etiologic factors for causing neonatal osteomyelitis have been discussed in the literature; however, premature rupture of the membranes has never been emphasized. We report on a neonate with osteomyelitis of the right humerus infected with an uncommon pathogen, Klebsiella pneumonia. In the absence of any perinatal disease, premature rupture of the membranes was suggested to be the cause of the illness. The infant was initially regarded as having Erb palsy because of the absence of systemic symptoms and lack of perinatal high-risk factors. Antibiotic administration was delayed for 3 weeks. Luckily, nearly complete recovery was noted after 2 months of follow up. We emphasize the importance of considering osteomyelitis in a newborn infant with limb palsy, particularly in the presence of premature rupture of the membranes of the mother. We also discuss the results of the microbial examination and significance of magnetic resonance imaging in neonatal osteomyelitis.

Anti-Bacterial Agents↗