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R H Wu

Publications and source records attributed to R H Wu.

At least 19 recordsLinked to original sources
PubMed2001

Value of quantitative analysis of mitral regurgitation jet eccentricity by color flow Doppler for identification of flail leaflet.

Early surgical intervention improves the outcome of patients with mitral regurgitation (MR) secondary to flail leaflet. Current criteria for the diagnosis of flail leaflet require a detailed definition of mitral valve anatomy, which is often challenging by transthoracic echocardiography (TTE) and, occasionally, even by transesophageal echocardiography (TEE). We studied 57 patients (mean age 63 +/- 15 years) with anatomically confirmed flail mitral leaflet and a control group of 57 patients (mean age 68 +/-14 years) with at least moderate MR but no flail leaflet. In patients with flail mitral leaflet, the mean angle formed by the axis of the MR jet and the plane of the mitral annulus was 33 +/- 11 degrees and 29 +/- 16 degrees when measured with TTE and TEE, respectively. In controls the mean angle was 66 +/- 16 degrees and 66 +/- 17 degrees by TTE and TEE, respectively (p <0.0001). Based on receiver- operating characteristic analysis, the optimal cutoff jet angle value for diagnosing flail mitral leaflet was 45 degrees with TTE (sensitivity 88%, specificity 88%), and 47 degrees by TEE (sensitivity 88%, specificity 88%). MR jet angles < or =45 degrees were also correctly identified by visual assessment of TTE images in >90% of cases, with good interobserver agreement (k = 0.76). Thus, quantitative analysis of MR jet eccentricity by color flow Doppler is highly sensitive and specific for diagnosing flail mitral leaflet.

Aged↗
PubMed2001

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: decrease in regional cerebral blood volume in hyperintense subcortical lesions inversely correlates with disability and cognitive performance.

BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an arteriopathic syndrome related to a genetic defect on chromosome 19. Characteristic changes in CADASIL can be observed onT2-weighted MR images in the subcortical white matter. The purpose of this study was to measure changes of regional cerebral blood volume (rCBV) with dynamic contrast-enhanced MR imaging and to correlate the changes to disability and cognitive performance. METHODS: We obtained rCBV measurements of 24 individuals with proven CADASIL on a 1.5-T MR imaging unit. A susceptibility-weighted MR imaging sequence was used for bolus tracking. Principles of the indicator dilution theory were applied to estimate values of absolute rCBV (mL/100 g). Disability was determined by using the Rankin scale, and overall cognitive performance was assessed by using the Mini-Mental State Examination. RESULTS: The mean rCBV in the subcortical white matter that was hyperintense on the T2-weighted images (2.7 +/- 0.8 mL/100 g) was significantly lower than the rCBV in the white matter that appeared normal on the T2-weighted images (4.4 +/- 1.3 mL/100 g) (P <.05). The mean rCBV in the gray matter was within the normal range (8.3 +/- 1.7 mL/100 g). Both cognitive impairment and disability negatively correlated with rCBV in the subcortical white matter that was hyperintense (P <.05) but not with rCBV in the normal appearing white matter. rCBV did not correlate with age. CONCLUSION: rCBV measured in the hyperintense subcortical white matter in individuals with CADASIL was decreased and inversely correlated with disability and cognitive impairment.

Adult↗
PubMed2000

Effects of three different doses of a bolus injection of gadodiamide: assessment of regional cerebral blood volume maps in a blinded reader study.

BACKGROUND AND PURPOSE: Reconstruction of first-pass bolus information to derive regional cerebral blood volume (rCBV) maps is commonly performed in many centers; however, various protocols with different doses of paramagnetic contrast injections have been reported. We evaluated the dose dependency of rCBV maps in a brain tumor population by using three different doses of gadodiamide injection to evaluate their diagnostic accuracy in blinded reader sessions. METHODS: Eighty-three patients with intraaxial brain tumors (72 gliomas) were studied at three centers and randomized to receive a bolus injection of 0.1, 0.2, or 0.3 mmol/kg per body weight of gadodiamide. rCBV maps were generated from T2*-weighted gradient-echo echoplanar sequences at 1.5 T. Data processing was performed according to the indicator dilution theory. RESULTS: The mean contrast-to-noise ratio (CNR) was significantly different between gadodiamide doses of 0.1 and 0.2 mmol/kg (CNR = 8.7 and 15.7) and between 0.1 and 0.3 mmol/kg (CNR = 17.7). No significant difference was found between doses of 0.2 and 0.3 mmol/kg. Sensitivity for the differentiation of benign and malignant brain tumors was 80%, 95%, and 91%, and specificity was 45%, 54%, and 43% by blinded readings at 0.1, 0.2, and 0.3 mmol/ kg, respectively, as compared with histologic findings. Nonblinded readings had a sensitivity of 83%, 100%, and 90% and a specificity of 82%, 100%, and 73% at 0.1, 0.2, and 0.3 mmol/kg, respectively. CONCLUSION: A dose of 0.2 mmol/kg of gadodiamide is recommended for reconstruction of rCBV maps if data are acquired with the T2*-weighted protocol described.

Blood Volume↗
PubMed1999

MR measurement of regional relative cerebral blood volume in epilepsy.

The purpose of this study was to evaluate the utility of magnetic resonance (MR) relative cerebral blood volume (rCBV) maps for studying regional hemodynamic changes in interictal and ictal epilepsy patients. Ten epilepsy patients were examined on a 1.5 T MR system. Nine patients were investigated interictally and one patient ictally. In the nine interictal patients, the dynamic plane was defined coronally through the hippocampus symmetrically. For the ictal patient, an axial dynamic plane was defined and the patient was scanned during seizure. Positron emission tomography (PET) studies were performed in 8 of the 10 patients. Lower rCBV of the left hippocampus was predicted by rCBV maps in seven of the nine interictal patients. The mean ratios of rCBV were 1.96 for left hippocampus/white matter and 2.49 for right hippocampus/white matter. The difference between these two ratios is statistically significant (P = 0.01, t-test). In two of the nine interictal temporal lobe epilepsy patients, lower rCBV areas were observed in the right hippocampus. In the ictal patient, the regional rCBV map demonstrated increased blood volume in the lesions. In eight of eight patients who underwent PET studies, MR rCBV findings were consistent with PET findings. The results show that regional hemodynamic changes in epilepsy can be evaluated with dynamic contrast-enhanced MR imaging. MR rCBV maps are sensitive to characterize seizure foci both ictally and interictally.

Adult↗
PubMed1999

Comparison of the diagnostic information in relative cerebral blood volume, maximum concentration, and subtraction signal intensity maps based on magnetic resonance imaging of gliomas.

RATIONALE AND OBJECTIVES: The authors investigate the validity of regional relative cerebral blood volume (rCBV) versus maximum concentration and subtraction signal intensity (SI) maps using simple reconstruction modes in patients with gliomas. METHODS: Twenty-five patients were studied using a 1.5 T magnetic resonance imaging scanner. To calculate the rCBV map, the magnetic resonance susceptibility effect SI/time curves were first transformed into concentration/time curves; then a gamma-variate function was fitted and the area under the curve was integrated. From the concentration/time data, the maximum concentration (MAX) maps were calculated pixel per pixel as the maximum peak amplitude of the concentration/time curve. Subtraction (SUB) maps are a result of simple image subtraction of pixelwise baseline SI minus the highest peak of susceptibility change pixel per pixel. Region of interest means SI measurement of the different maps was compared using statistical t test correlation. RESULTS: Normal gray to white matter contrast did not show a significant difference among the rCBV, MAX, and SUB maps. Based on statistical evaluation, the low-grade lesions did not differ significantly in the rCBV, MAX, and SUB maps. The group with high-grade lesions (12 patients) showed no significant difference in standardized rCBV, MAX, and SUB maps. CONCLUSION: Compared to rCBV maps, the simple MAX and SUB maps demonstrated good correlation in both high-grade and low-grade gliomas. This simpler approach could establish first-pass reconstruction in clinical settings because it reduces the need for time-consuming postprocessing.

Adult↗
PubMed1998

Diffusion-weighted MRI in transient global amnesia: elevated signal intensity in the left mesial temporal lobe in 7 of 10 patients.

Prompted by the findings of previous studies with positron emission tomography and single photon emission computed tomography, which demonstrated hypoperfusion or hyperperfusion in the left temporal lobe in isolated patients with transient global amnesia (TGA), we compared the sensitivity of diffusion-weighted (DW) magnetic resonance imaging (MRI) with that of conventional T1- and T2-weighted MRI in patients with TGA. Ten patients with the typical syndrome of a pure TGA were included in the study. For all patients, a coronal DW sequence, a steady-state free precession (SSFP) sequence, and conventional T1- and T2-weighted turbo spin-echo sequences were obtained. Seven of the 10 patients had elevated signal intensity in the left hippocampal region on DW MRI; moreover, 3 of these 7 patients exhibited bilateral signal abnormality in this sequence. All conventional T1- and T2-weighted images as well as all follow-up studies were normal. The signal elevation in DW MRI correlates with a decrease in the interstitial space and with cellular edema in the temporal lobe during TGA. The underlying pathomechanism causing this cellular edema cannot be clearly outlined using DW MRI. Our data are, however, compatible with spreading depression. This is the first study to show that DW MRI is a sensitive MRI method for evaluating TGA, especially in the early stage of the disease.

Aged↗
PubMed1998

MRI assessment of cerebral blood volume in patients with brain infarcts.

MRI perfusion studies have focussed mainly on acute ischaemia and characterisation in ischaemia. Our purpose was to analyse regional brain haemodynamic information in acute, subacute, and chronic ischaemia. We performed 16 examinations of 11 patients on a 1.5 T MR images. Conventional and dynamic contrast-enhanced imaging were employed in all examinations. For the dynamic susceptibility sequences, a bolus (0.2 mmol/kg) of gadopentetate dimeglumine was injected. Reconstructed regional relative cerebral blood volume (rCBV) maps, bolus maps, and conventional images were analysed by consensus reading. In all examinations decreases in rCBV were observed in the lesions. The distribution of regional rCBV in lesions was heterogeneous. The rCBV of the periphery of the lesions was higher than that at their center. There was a correlation between the time since onset and abnormalities on the rCBV map and T2-weighted images (T2WI). In the early stage of acute stroke, the abnormalities tended to be larger on the rCBV than on T2WI. Many patterns of bolus passage were observed in ischaemic regions. rCBV maps provide additional haemodynamic information in patients with brain infarcts.

Adult↗
PubMed1996

Diffusion measurements in the ischemic human brain with a steady-state sequence.

RATIONALE AND OBJECTIVES: The authors evaluate the clinical usefulness of a diffusion-weighted steady-state free-precession (SSFP) sequence to detect acute and subacute ischemic changes. METHODS: Twenty-four patients were examined on a 1.5-tesla scanner, using a SSFP-sequence (repetition time [TR]/ echo time [TE] = 22/3-8 mseconds). The slice thickness was 5 mm, 10 averages, 57 seconds per slice. The diffusion gradient strength was 23 millitesla/m, with b-values from 165 to 598 seconds/mm2. Diffusion-weighted images (DWI) were compared with T2-weighted images. RESULTS: The diffusion-weighted SSFP sequence produced diagnostic quality images in 23 of 24 patients. Diffusion depicted (group 1: 0-12 hours) more acute lesions (3 of 6) than T2-weighted images (2 of 6); the mean lesion diameter depicted by diffusion was 10.9 mm (standard deviation [SD], 12.3) and in T2-weighted images was 4.7 mm (SD 6.8). A significant correlation (P < 0.017) in subacute lesions was found when diffusion was compared with turbo spin echo (mean size difference/T2 = 18.5/17.5 mm, SD 13.2/12.2). CONCLUSIONS: The diffusion-weighted SSFP-sequence is more sensitive in acute ischemia and delineates likewise in subacute ischemia, when compared with T2-weighted imaging.

Adult↗
PubMed1995

[Echo-planar imaging of the brain].

In this review, the clinical utility of echoplanar techniques in MRI of the brain is discussed. Comparison of high-resolution EPI with SE/turbo-SE shows high image quality of EPI in the supratentorial brain. In the infratentorial region, however, susceptibility artifacts limit image quality. For the assessment of neuronal brain activation utilizing the intrinsic contrast of blood (BOLD), EPI has definite advantages over other techniques of functional MRI. Due to its superior temporal resolution and multislice capabilities, EPI allows for analysis of complex neuronal activation patterns. Diffusion imaging benefits from the lack of bulk motion artifacts and serves primarily to detect early stroke. Three methods of perfusion imaging (rel. blood volume, rel. blood flow) are discussed: the susceptibility artifact method (T2*), the relaxitivity method (T1), and the signal-labelling technique (STAR). Perfusion imaging may have a clinical impact in the assessment of brain tumors and cerebral ischemia.

Artifacts↗
PubMed1991

Pathological studies of CT findings in supratentorial astrocytoma. Correlation between low-density lesions and changes in fine structure.

CT findings and pathological features of 102 supratentorial astrocytomas were evaluated, and the surgically removed specimens of 10 cases studied by electron microscopy. Five pathological indices-anaplasia, vascularity, interstitial water content, necrosis and tumor fibers were graded from 1 to 4, and studies by the double-blind method. CT scans were divided into 4 groups according to attenuation coefficients and contrast enhancement. The data were statistically analysed. The results showed that the interstitial water content and tumor fibers were statistically different in low-density lesions and isodensity or hyperdensity lesions. The peritumoral low-density specimens correlated well with infiltrated tumor cells, which had swollen mitochondria. No definite correlation was found between the histological subtypes of astrocytomas and CT images. These findings suggest that high water content and lower physical density are responsible for the low-density of astrocytomas. Abnormalities of capillary ultrastructure result in the accumulation of contrast medium. The peritumoral area of low-density seen on CT scans is the real extent of the edematous tumor. But it is impossible to distinguish the histological subtypes of astrocytomas by CT findings.

Astrocytoma↗
PubMed1990

Preservation of physiological growth hormone (GH) secretion in idiopathic short stature after recombinant GH therapy.

This study was undertaken to assess the recovery of spontaneous GH secretion 48 h after the cessation of GH therapy in children with idiopathic short stature treated with recombinant DNA-generated human GH (rhGH-M). Eleven prepubertal children with GH responses of 10.0 ng/mL or more after provocation were divided into therapeutic (n = 7) and control (n = 4) groups. GH was sampled every 20 min for 24 h in six treated and three control patients. One treated and one control patient had 12-h overnight studies because of their weight. The sampling studies were carried out before GH therapy was initiated and 48 h after rhGH was discontinued after 12 months of therapy. Three patients in the treated group also underwent a 24-h study at the 6 month time point. The treated group started treatment with rhGH (0.1 mg/kg), given three times a week. The results showed that pre- and posttreatment GH secretory profiles were comparable with respect to the number of peaks, mean concentrations, peak amplitude, and secretory rate. At the 6 month point, the mean GH and peak GH amplitude (n = 3) were greater than the means of the treatment group (n = 7) at the 0 and 12 month points, but the difference was not statistically significant. Somatomedin-C rose in the treated group from 0.42 +/- 0.1 to 1.25 +/- 0.3 U/mL (mean +/- SD; P less than 0.01). In the control group it rose from 0.56 +/- 0.1 to 1.16 +/- 0.8 U/mL (mean +/- SD; P greater than 0.05) because one patient entered puberty in the 12-month period of observation; his somatomedin-C level rose from 0.72 to 2.5 U/mL. We conclude that exogenous GH therapy does not interfere with the maintenance of endogenous pulsatile secretion of GH. These data show that exogenous GH therapy does not interfere with the maintenance of endogenous pulsatile secretion of GH and provide evidence for the resilience of the GH secretory system in the growing child.

Child↗
PubMed1989

[Evaluation of the quality of the crude drug of Panax quinquefolium linn. cultivated in Heilongjiang Province].

A comparison has been made between the Panax quinquefolium introduced and cultivated in Heilongjiang province and the wild one imported from the U.S. in terms of properties, structures and principal chemical constituents. The result shows that the two kinds are very similar or close to each other, though in properties and structures they are slightly different, and in the contents of total saponins, ginsenosides Rb 1 and Re, the cultivated one is lower.

Ginsenosides↗
PubMed1988

Effect of growth hormone treatment on sleep EEGs in growth hormone-deficient children.

Total sleep time, sleep stages 1-4, REM, REM latency, and sleep efficiency were analyzed in seven children with growth hormone deficiency (GHD) before and after growth hormone (GH) therapy. Before GH therapy, GHD children spent 19.5% of their total sleep time in REM sleep, 9.7% in stage 1, 41.0% in stage 2, 10.0% in stage 3, and 19.7% in stage 4. GHD children had more stage 1 and 3 sleep and less REM as compared with age-matched normal children reported by Williams et al. After GH therapy was initiated, six of the seven patients had decreases in the duration of stage 3 sleep, with an average decrease of 21.8 min. The difference between stage 3 sleep before and during GH treatment was significant, with a p value of less than 0.025. When the results were expressed as the percentage of the total sleep period, the difference was also significant, (10.0 +/- 2.0 to 7.5 +/- 3.1%, mean +/- SD; p less than 0.05). No other sleep parameters were significantly affected by GH therapy. The changes observed in stage 3 sleep, non-REM sleep, and the lack of any other changes in sleep before and after GH therapy have not been described before in GH-deficient children. They differ from studies in normal humans and animals which showed that REM sleep increased with administration of growth hormone. These differences suggest that GH deficiency is associated with a specific sleep EEG anomaly that is corrected in part by GH therapy.

Child↗
PubMed1987

Reversibility of deficient sleep entrained growth hormone secretion in a boy with achondroplasia and obstructive sleep apnea.

Obstructive sleep apnea may lead to disordered sleep architecture and impair the physiologic slow wave sleep related growth hormone release. Obstructive sleep apnea occurs with craniofacial syndromes and in children with airway narrowing, pharyngeal hypoplasia, tonsillar adenoidal hypertrophy, micrognathia and achondroplasia. To examine the relationship between disordered sleep and growth hormone release we studied a 9 year old male with achondroplasia, growth failure (3 cm/year) and obstructive sleep apnea. Polysomnography data and a 20 min sampling for sleep entrained growth hormone showed before therapeutic tracheostomy numerous apneic episodes, absent slow wave sleep and abnormal low growth hormone secretion during sleep. Normalized slow wave sleep entrained growth hormone secretion after tracheostomy led to a sustained increase in growth rate. Normal growth rate (greater than 5 cm/year) continues 2 years after tracheostomy. We conclude that obstructive sleep apnea may impair sleep related growth hormone release. Obstructive sleep apnea may be a useful model for other diseases in which growth failure and sleep disturbances are linked.

Achondroplasia↗
PubMed1987

[Reactivity of monoclonal antibodies ALT-01 and ALT-04 and identification of lung cancer-associated antigens].

Two IgG1 type monoclonal antibodies ALT-01 and ALT-04 were prepared by two different immunization schedules. ALT-01 was generated by fusing murine myeloma NS-1 cells with splenocytes from a BALB/c mouse immunized by human lung squamous carcinoma cells, which were coated by antisera to mixed human lymphocytes. For preparation of ALT-04, human lung squamous carcinoma xenograft-bearing nude mice were injected I. P. with the spleen cells of normal BALB/c mice in order to acquire immunofunction. The spleen cells from these tumor-bearing nude mice were fused with NS-1 cells. Then, these hybridomas were screened and cloned for 3 times. Two antibodies were shown to recognize the surface antigen on human lung carcinoma cells and several kinds of tumor cell lines but not those on normal cell lines. ALT-01 reacted to neither human lung carcinoma tissue nor its xenograft. ALT-04 reacted to human lung carcinoma tissue, of which, reaction to adenocarcinoma was the strongest but not to various normal tissues. Immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis and autoradiography was used to detect the associated antigen in 35S-labeled human lung carcinoma cells. Antigens, reacting to ALT-01, show one band of Mr 38,000 but those to ALT-04 reveal two bands of Mr 48,000 and 36,000.

Animals↗
PubMed1987

[Radioimmunodetection of human lung cancer xenografts by isotope labeling monoclonal antibody ALT-04 in nude mice].

Three nude mouse models bearing the human lung cancer were established from two fresh surgical specimens and one cell line. Tumor histological structure and cell morphology were similar before and after transplantation. The monoclonal antibody ALT-04 (McAb ALT-04) against human lung cancer was labeled by 125I, 131I and 201Tl. Radioimmunodetection study showed that all the three kinds of xenografts in nude mice were specifically located by McAb ALT-04. Imaging examination confirmed the ability of isotope labeling McAb ALT-04 to detect the presence of transplanted human lung cancer tissues without the aid of background subtraction manipulations. It is suggested that McAb ALT-04 have the possibility of locating in the tumor diagnosis and guiding in the treatment.

Animals↗