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Yung-Liang Wan

Publications and source records attributed to Yung-Liang Wan.

At least 19 recordsLinked to original sources
PubMed2006

The effects of single-trial averaging on the temporal resolution of functional MRI.

Computer simulations and event-related functional MRI (ER-fMRI) experiments were performed to investigate the effects of single-trial averaging and the corresponding contrast-to-noise ratio (CNR) on the minimal resolvable hemodynamic timing difference between brain areas. Three ER-fMRI sessions with temporally delayed (250, 500 and 1,000 ms) visual stimulations between two hemifields, each with 70 repeated single trials, were examined on two subjects. From the computer simulation, the temporal resolution improved as the CNR increased, which reached 500 and 100 ms for CNRs of 1.55 and 6.44, respectively. In the ER-fMRI experiments, the measured CNR increased as more single trials were averaged. The detectability of temporal differences was positively correlated (P<.05) with the CNR in all sessions for one subject but only in the 1,000-ms session for the other subject. Temporal resolution of 1,000 ms was achieved when more than 10 trials were averaged. The 500- and 250-ms delays might be differentiable when more than 20 trials were averaged, but the results were subject-dependent. This study demonstrated that the CNR could be significantly improved by single-trial averaging, which led to an improved temporal resolution of ER-fMRI. Temporal resolution in the range of hundreds of milliseconds was subject-dependent, which might be attributed to the intrinsic spatial variations in the timing of the blood oxygenation level-dependent (BOLD) response.

Adult↗
PubMed2006

Spontaneous isolated mesenteric fibromatosis: sonographic and computed tomographic findings with pathologic correlation.

Eight cases of spontaneous isolated mesenteric fibromatosis (SIMF) were retrospectively reviewed. Clinical presentations included palpable abdominal mass (n = 6), abdominal pain (n = 4), gastrointestinal bleeding (n = 2) and acute abdomen (n = 1). On sonography and computed tomography (CT), eight SIMFs (size range 3 to 24 cm, mean 14.8 cm) were categorized into four morphologic patterns: well-defined inhomogeneous, well-defined homogeneous, well-defined cystic or infiltrative mesenteric mass patterns. Well-defined inhomogeneous SIMF (n = 3) was correlated with the histopathologic finding of bundles of fibroblasts with unevenly intermingled hyaline and/or myxoid degeneration areas, whereas well-defined homogeneous SIMF (n = 2) showed scarce degenerative changes. Well-defined cystic SIMF (n = 2) were ascribed to the presence of large areas of myxoid and cystic degenerations. One SIMF presented as an infiltrative mesenteric mass and the patient died 10 months after diagnosis. Both cases of cystic SIMFs showed tumor recurrences and one patient died after 84 months. The other five patients were cured by radical tumor resection. In summary, sonography, similar to CT, is also useful for evaluating SIMF with protean morphologic features, ascribing to the underlying histopathologic changes with varied degrees of hyaline, myxoid or cystic degenerations.

Adult↗
PubMed2006

Imaging factors related to rotator cuff tear in patients with deltoid contracture.

BACKGROUND: Bony deformity and muscular malfunction around the shoulder induced by deltoid contracture may influence rotator cuff function and lead to subsequent tearing. The purpose of this study was to investigate the imaging and clinical factors related to rotator cuff tear in patients with deltoid contracture. METHODS: We retrospectively reviewed 48 shoulders in 44 patients with magnetic resonance imaging diagnosis of deltoid contracture and surgically-proven rotator cuff tear. These shoulders were subdivided into partial-thickness and full-thickness tear groups. Another 17 shoulders in 17 patients with deltoid contracture but no evident rotator cuff tear were included as the control group. The characteristics, including age, gender and imaging features, of these three groups were compared. RESULTS: Two patients who underwent initial operations for cuff tears required secondary operations for distal release of deltoid contracture. The age of patients with full-thickness tear was significantly greater than that of patients with partial-thickness tear or without tear. The winging angle of the glenoid (WAG) in the full-thickness tear group was significantly greater than that in the partial-thickness tear group. Patients with partial-thickness tear also had greater WAG than those without tear. However, WAG was not significantly correlated with the fibrotic size or age of the patient. CONCLUSION: In patients with deltoid contracture, age and WAG are associated with the development of rotator cuff tear. To prevent the occurrence of rotator cuff tear, early surgical release of deltoid contracture is highly recommended, especially in patients with greater WAG.

Adult↗
PubMed2005

Pathological changes in the brains of rabbits experimentally infected with Angiostrongylus cantonensis after albendazole treatment: histopathological and magnetic resonance imaging studies.

OBJECTIVES: To determine the effects of albendazole on rabbits infected with larvae of Angiostrongylus cantonensis by histopathological and magnetic resonance imaging (MRI) techniques. METHODS: Male rabbits were infected with 400 A. cantonensis larvae and treated with albendazole (5 mg/kg/day) for 2-14 days on day 5, 10, 15 or 20 post-infection. RESULTS: Although there were pathological changes in the brains, MRI revealed unremarkable findings in the untreated group. However, the treated rabbits exhibited eosinophilic meningitis, choroid plexus inflammation, meningeal congestion, encephalitis, perivascular cuffing and meningitis, and were also found to have abnormal signal intensities on brain MR images in the 20 day post-infection treated group. CONCLUSIONS: Pathological changes in the brains of the treated rabbits are more severe than those without albendazole treatment, suggesting that the drug may not be very suitable for the treatment of cerebral angiostrongyliasis.

Albendazole↗
PubMed2005

Computed tomography findings in fatal cases of enormous hepatic portal venous gas.

AIM: To assess the computed tomography (CT) findings in the patients with hepatic portal venous gas (HPVG) who presented with a short fatal clinical course in our hospital in order to demonstrate if there was any sign for prediction. METHODS: Between January 1997 and December 2000, CT scan of the abdomen was performed on 949 patients with acute abdominal pain in our emergency department. Five patients were found having HPVG. The CT images and clinical presentations of all these five patients were reviewed. RESULTS: In reviewing the CT findings of the cases, HPVG in bilateral hepatic lobes, abnormal gas in the superior mesenteric veins, small bowel intramural gas, and bowel distension were observed in all patients. Dry gas in multiple branches of the mesenteric vein was also revealed in all cases. All the patients expired due to irreversible septic shock within 48 h after their initial clinical presentation in emergency room. Two patients had acute pancreatitis with grade D and E Balthazar classification and they expired within 24 h due to progressing septic shock under aggressive medical treatment and life support. Two patients with underlying end stage renal disease expired within 48 h even though emergent surgical intervention was undertaken. The excited bowels revealed severe ischemic change. One patient expired only a few hours after the CT examination. CONCLUSION: HPVG is a diagnostic clue in patients with acute abdominal conditions, and CT is the most specific diagnostic tool for its evaluation. The dry mesenteric veins are the suggestive fatal sign, especially for the deteriorating patients, with the direct effect on gastrointestinal perfusion.

Abdomen, Acute↗
PubMed2005

Persistence of lung inflammation and lung cytokines with high-resolution CT abnormalities during recovery from SARS.

BACKGROUND: During the acute phase of severe acute respiratory syndrome (SARS), mononuclear cells infiltration, alveolar cell desquamation and hyaline membrane formation have been described, together with dysregulation of plasma cytokine levels. Persistent high-resolution computed tomography (HRCT) abnormalities occur in SARS patients up to 40 days after recovery. METHODS: To determine further the time course of recovery of lung inflammation, we investigated the HRCT and inflammatory profiles, and coronavirus persistence in bronchoalveolar lavage fluid (BALF) of 12 patients at recovery at 60 and 90 days. RESULTS: At 60 days, compared to normal controls, SARS patients had increased cellularity of BALF with increased alveolar macrophages (AM) and CD8 cells. HRCT scores were increased and correlated with T-cell numbers and their subpopulations, and inversely with CD4/CD8 ratio. TNF-alpha, IL-6, IL-8, RANTES and MCP-1 levels were increased. Viral particles in AM were detected by electron microscopy in 7 of 12 SARS patients with high HRCT score. On day 90, HRCT scores improved significantly in 10 of 12 patients, with normalization of BALF cell counts in 6 of 12 patients with repeat bronchoscopy. Pulse steroid therapy and prolonged fever were two independent factors associated with delayed resolution of pneumonitis, in this non-randomized, retrospective analysis. CONCLUSION: Resolution of pneumonitis is delayed in some patients during SARS recovery and may be associated with delayed clearance of coronavirus, Complete resolution may occur by 90 days or later.

Adolescent↗
PubMed2005

Evaluating hip labral tears using magnetic resonance arthrography: a prospective study comparing hip arthroscopy and magnetic resonance arthrography diagnosis.

PURPOSE: To evaluate the sensitivity and accuracy of magnetic resonance arthrography (MRA) with true sagittal scout image mapped radial reformation in localizing hip labral tears. TYPE OF STUDY: Case series. METHODS: Thirty patients were examined with hip MRA because of suspected labral tears. Every patient underwent normal hip arthrography and MR examinations using a 1.5-T scanner with a 3D-FLASH pulse sequence. Multiplanar reformation using double oblique technique produced radial reformatted rotation images with 10 degrees increment on the acetabular rim. Labral tears were annotated as anterior-superior (AS), anterior-inferior (AI), posterior-superior (PS), and posterior-inferior (PI) quadrant based on the cranial-caudal axis in true sagittal reformatted scout localizing image. Patients with positive MRA findings were counseled to have the arthroscopic hip procedure. RESULTS: Five patients showed no MRA indication of labral tear. Of 25 patients who had MRA evidence of labral tear, 17 underwent arthroscopic hip surgery. One patient had only synovial process in the hip joint near the suspected MRA area. The remaining 16 operated patients had labral tears with a total of 21 quadrant lesions on arthroscopy (distributed as AS, 14; AI, 3; PS, 2; and PI, 2). Radial reformatted images revealed accurate mapping with arthroscopic findings in 21 of the 22 quadrant lesions. The sensitivity and accuracy of MRA for the diagnosis of hip labral tear were 100% and 94%, respectively, and the sensitivity and accuracy of radial reformatted MRA for mapping the tear location were 100% and 96%, respectively. CONCLUSIONS: MRA using radial reformatted images with a true sagittal localizer may achieve superior success rates in diagnosing hip labral lesions and in guiding the arthroscopist in portal selection, thus rendering location of hip labral tears simpler in surgery. It supplied detailed preoperative information to the surgeon, avoiding unnecessary surgery for patients if the diagnosis was unconfirmed. LEVEL OF EVIDENCE: Level III.

Acetabulum↗
PubMed2005

Magnetic resonance imaging findings in the brains of rabbits infected with Angiostrongylus cantonensis: a long-term investigation.

Because magnetic resonance (MRI) imaging is a superior technique in delineating pathological changes in cerebral angiostrongyliasis, it should also be an optimal imaging modality in monitoring long-term changes in the brains of animals infected with Angiostrongylus cantonensis. In this study, MRI and histological techniques were used to observe the changes in the brains of 7 rabbits infected with the third-stage larvae of A. canronensis. Changes were monitored by MRI from day 0 to day 207 postinfection (PI). Hyperintense lesions on T2-weighted MR brain images were first observed on day 22 PI and hallmarks of abnormalities were noted on day 35 PI. Hyperintensities on brain MR images remained up to day 207 PI. Histological examination from days 108 to 207 PI revealed meningeal congestion, choroid plexus inflammation, infarction, granuloma with embedded larva, gliosis, and hemorrhage in the brain tissues. These findings suggest that hosts infected with A. cantonensis may undergo pathological changes in the brain tissues for more than 200 days PI. Moreover, severe abnormalities may occur as early as the fifth week PI.

Angiostrongylus cantonensis↗
PubMed2005

Effects of heart rate on motion artifacts of the aorta on non-ECG-assisted 0.5-sec thoracic MDCT.

OBJECTIVE: Our aim was to evaluate the effects of heart rate on aortic motion artifacts on 0.5-sec non-ECG-assisted thoracic MDCT. MATERIALS AND METHODS: A total of 124 non-ECG-assisted thoracic MDCT scans with satisfactory simultaneous ECG data were reviewed. Scans were grouped according to patient heart rates (beats per minute [bpm]: group A, 46-55; B, 56-65; C, 66-75; D, 76-85; E, 86-95; and F > 95). The groups were compared regarding the presence, locations, and spatial distributions of pulsation artifact, number of slices affected, maximum amplitude of pulsation, continuity of artifact, and the presence of superior vena cava (SVC) pseudoflaps. RESULTS: Of the 124 scans, 114 (91.9%) had aortic motion artifacts, with prevalence ranging from 85.3% (66-75 bpm) to 100% (65 bpm or less). Of the 114 motion artifacts, all affected the ascending aorta, 105 (92.1%) involved the left anterior and right posterior aspects of the aortic circumference, and 106 (93%) were associated with SVC pseudoflaps. Group B had significantly greater numbers of images with artifacts (p < 0.001-0.006), greater artifact amplitudes (p < 0.001-0.002), and a higher continuity trend for the artifacts (p = 0.003-0.194) than did the other five groups. CONCLUSION: Aortic motion artifacts are frequently seen on thoracic MDCT, especially in patients with heart rates of 65 bpm or less. The presence of a SVC pseudoflap is helpful for distinguishing artifacts from dissection. If aortic disease is suspected, then measures to reduce motion artifact, such as ECG-gating, should be considered.

Aorta, Thoracic↗
PubMed2005

Contracture of the deltoid muscle: sonographic evaluation with MRI correlation.

OBJECTIVE: This article evaluates the sonographic features of deltoid contracture (DC) with MRI correlation. MATERIAL AND METHODS: Two reviewers evaluated the imaging features in 22 painful shoulders of 20 patients with a sonographic diagnosis of DC and a subsequent confirming MRI study. The sonographic and MRI findings with regard to the lesion extent (assessed by a 3-point scale: 1 = less than or equal to one third of the longitudinal deltoid length involved, 2 = greater than one third and less than or equal to two thirds involved, and 3 = greater than two thirds involved), transverse lesion morphologic appearance, and maximal transverse diameter measured were compared with kappa statistics and Wilcoxon's signed rank test, respectively. RESULTS: Compared with MRI, there were two false-positive diagnoses of DC on sonography. Among the 20 true-positive diagnoses, sonography showed good agreement with MRI in assessing the lesion extent (kappa = 0.796, p < 0.001). Three sonographic lesion morphologic patterns for hyperechoic lesions (I = with multiple < 8-mm hypoechoic spots, II = heteroechoic lesions with predominant 8-15-mm hypointense areas, and III = > 15-mm calcified nodules, respectively) showed excellent agreement with three MRI lesion patterns (I = multiple < 8-mm hypointense spots, II = predominant 8-15-mm hypointense areas, and III = > 15-mm hypointense nodules, respectively) (kappa = 0.921, p < 0.001). However, the maximum lesion diameters appeared significantly larger on sonography than on MRI (2.8 +/- 0.6 cm vs 2.0 +/- 0.8 cm, mean +/- SD; p < 0.001), which was plausibly ascribed to the better sonographic delineation of hyperechoic immature fibrotic tissues. CONCLUSION: Sonography is helpful for evaluating DC and correlates well with MRI.

Adult↗
PubMed2005

Rosai-Dorfman disease with dural sinus invasion. Report of two cases.

Rosai-Dorfman disease (RDD) is an idiopathic proliferation of histiocytes that affects the lymph nodes. Central nervous system involvement in the absence of nodal disease is extremely rare. On neuroimaging studies, intracranial RDD appears as solitary or multiple well-circumscribed, dura-based lesions. The authors report on two cases of RDD with locally aggressive features including dural sinus invasion, which to their knowledge has never before been described. A 60-year-old woman presented with progressive dizziness and vertigo that had lasted for 1 week. Cranial computerized tomography and magnetic resonance imaging revealed an extraaxial homogeneous lobulated enhancing mass involving the right occipital lobe and the right cerebellar hemisphere. Invasion of the right transverse sinus was identified on a cerebral digital subtraction angiogram. A 59-year-old man with no prior medical illness experienced progressive weakness of both upper extremities and a partial complex seizure. Magnetic resonance imaging of his brain revealed a well-circumscribed enhancing mass in the left frontal lobe with extension to the right frontal lobe and invasion of the superior sagittal sinus. Both patients underwent resection of their brain masses. Pathological studies identified the disease as RDD in both patients.

Cranial Sinuses↗
PubMed2004

Quality assurance of clinical MRI scanners using ACR MRI phantom: preliminary results.

Clinical magnetic resonance imaging (MRI) scanners play an important role in the diagnosis of diseases and management of patient treatment. Quality assurance (QA) of the clinical MRI scanners is mandatory to obtain optimal images in a modern hospital. In this report, the phantom test for the American College of Radiology (ACR) MRI accreditation is used as the essential part of the MRI QA protocols. Seven important assessments of MR image quality are included as follows: geometric accuracy, high-contrast resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, and low-contrast object detectability. In addition, signal-to-noise ratio and central frequency are monitored as well. The MRI QA procedures were applied to four clinical MRI scanners in our institute twice within 3 months. According to the QA results, the service engineers were more efficient in solving scanners problems when the ACR phantom test was run.

Humans↗
PubMed2004

Testicular dislocation: an uncommon and easily overlooked complication of blunt abdominal trauma.

STUDY OBJECTIVE: We report testicular dislocation as an unusual complication of blunt abdominal trauma. METHODS: The computer data bank of Chang Gung Memorial Hospital was searched for the period from 1987 to 2002, and 1,967 male patients with blunt abdominal trauma were admitted to the emergency department. Among these patients, records of 9 patients associated with testicular dislocation were collected. A retrospective review of the clinical records, abdominal computed tomography (CT) results, and subsequent scrotal sonograms was jointly performed by 2 radiologists, an emergency physician, and a trauma surgeon. RESULTS: Of these 9 patients (age range 6 to 53 years; mean 23 years), 7 patients were in motorcycle crashes, 1 patient had explosive injury, and 1 patient had seat belt injury. Associated testicular dislocation was initially missed in all patients. CT for evaluating blunt abdominal trauma revealed liver lacerations in 2 patients and pancreatic fracture, pancreatitis, bowel perforation, pubic bone fracture, and contralateral inguinal hernia in 1 each. Typical CT findings of testicular dislocation (empty scrotum and displaced testis) were retrospectively seen in 7 patients, but prompt CT diagnosis of testicular dislocation was achieved only in 3 patients, who were subsequently treated with closed manual reduction, obviating surgery. In the remaining 2 patients, CT examination did not include the scrotum and testicular dislocation, which was diagnosed by subsequent sonography. Delayed diagnosis occurred in 6 patients (duration 3 to 60 days; mean 19 days). Five of the patients underwent orchiopexy, and 1 underwent orchiectomy. CONCLUSION: In blunt abdominal trauma patients, associated testicular dislocation is easily overlooked. A complete physical examination in the trauma patient, including palpation of both testes, is strongly recommended.

Abdominal Injuries↗
PubMed2004

Temporal resolving power of perfusion- and BOLD-based event-related functional MRI.

Functional magnetic resonance imaging (fMRI) based on both perfusion and blood oxygenation level-dependent (BOLD) contrasts has been widely applied in spatiotemporal mapping of the human brain function. Temporal resolving power of fMRI is limited by the smoothed hemodynamic response function dispersed from the neuronal activity. In this study, temporal modulation transfer functions were utilized to quantify the resolving powers of perfusion and BOLD fMR signals in time domain. The impulse response function was determined using brief visual stimulations and event-related image acquisition schemes. An important feature of arterial spin labeling techniques is that quantitative perfusion and BOLD signals could be simultaneously acquired. This simultaneous BOLD response may arise from signals that are more proximal to capillary beds, and its temporal resolution may be different from that of the typical BOLD response. Therefore, we assessed and compared the temporal resolving capabilities of perfusion, simultaneous BOLD, and the typical BOLD response obtained from the gradient echo EPI pulse sequence. Full-width-at-half-maximums of perfusion and simultaneous BOLD measurements were significantly smaller than that of BOLD ones (4.3+/- 0.6 s vs 5.5 +/- 0.9 s, p<0.02 and 4.7 +/- 1.3 s vs 5.5 +/- 0.9 s, p<0.01, respectively). The corresponding temporal resolving powers of perfusion and simultaneous BOLD signals were statistically better than that of BOLD signals (0.23 +/- 0.03 Hz vs 0.17 +/- 0.02 Hz, p<0.01 and 0.21 +/- 0.04 Hz vs 0.17 +/- 0.02 Hz, p<0.01, respectively). Our results showed that the typical BOLD response was significantly smoothed from the perfusion response, thus resulting in a degraded temporal resolving power. However, results from the simultaneous BOLD and perfusion measurements were not significantly different. Biophysical implications of the experimental outcomes were further investigated using a computer simulation based on the Balloon model. By fitting the measured data into the model, an apparently longer transit time was obtained for the typical BOLD signal (1.7 s), comparing to that for the simultaneous BOLD one (1.2 s). Therefore, the simultaneous BOLD signal was regarded as less susceptible to the variations from local draining veins. Combining the simulation result with the significantly discrepant resolving powers between the two BOLD signals, we speculated that the blurred effects from large vessels played a predominant role that further reduced the temporal resolution of the BOLD-based fMRI from the perfusion response.

Cerebrovascular Circulation↗
PubMed2004

Preoperative magnetic resonance imaging evaluation for breast cancers after sonographically guided core-needle biopsy: a comparison study.

BACKGROUND: The aim of the study was to evaluate the efficacy of contrast-enhanced magnetic resonance imaging (MRI) for preoperative assessment of palpable breast cancer after sonographically guided percutaneous core-needle biopsy. METHODS: Thirty-six breast cancers in 35 women that had been diagnosed by sonographically guided core-needle biopsy prior to subsequent MRI were evaluated in this retrospective study. Radiological and pathological reports, multiplicity, retroareolar involvement, and the size of the breast cancers were reviewed. The cancer sizes, as derived from sonography and enhanced MRI, were correlated with histological size in greatest diameter by means of Pearson's correlation. The threshold value for significance was set at P <.05. RESULTS: Synchronous breast cancers were revealed in the index cases by means of enhanced MRI (10), sonography (8), and mammography (7). Two of the 36 index cancers (5.6%) benefited from MRI assessment. Retroareolar cancer extension was observed with enhanced MRI in five index cancers. Of these, one was also noted on both a sonogram and a mammogram. Four of the index cancers (11.1%) benefited from the enhanced MRI. Overall, five index cancers (13.9%) benefited from the enhanced MRI. With a gold standard of histology, the mean cancer sizes were underestimated by sonography and overestimated by enhanced MRI. In comparison with sonography, a stronger association was noted between MRI and histological measurements, with coefficients of 0.657 and 0.882, respectively (P <.001). CONCLUSIONS: In a clinical setting, MRI for preoperative assessment of breast cancers is warranted. Minimally invasive, percutaneous core-needle biopsy did not alter the clinical efficacy of the MRI evaluation.

Adult↗
PubMed2004

Alteration of antibodies against the fifth-stage larvae and changes in brain magnetic resonance images in experimentally infected rabbits with Angiostrongylus cantonensis.

Magnetic resonance (MR) imaging has been suggested to be helpful in delineating the lesions during the acute phase of angiostrongyliasis caused by Angiostrongylus cantonensis. In this study, antibody titers in serum samples of 3 rabbits were determined by enzyme-linked immunosorbent assay, and brain MR images were obtained from 6 rabbits. The antibody titer elevated rapidly in the first 4 wk postinfection (PI) before reaching a plateau. However, suspicious changes in brain MR images near the left lateral ventricle and hippocampus were found only in 1 rabbit on day 28 PI. These findings indicate that immunologic responses in the central nervous system at the early stage of angiostrongyliasis are not sufficient to be observed by image studies.

Acute Disease↗