Poon-Ung Chieng

Gastric emptying in head-injured patients

Objective:Most patients with moderate to severe head injury (HI) initially do not tolerate enteral feedings. Intolerance to nasogastric feeding is also commonly observed after HI. Quantitative measurements of gastric emptying (GE), to determine a possible mechanism for intolerance to enteral feeding, are lacking.Methods:We prospectively evaluated gastric emptying half-time (GET1/2) of liquid meals in 35 patients with moderate to severe HI.Results:In comparison with 16 age-matched healthy control subjects (29.4 ± 3.7 min), GET1/2 was significantly prolonged (57.2 ± 20.8 min, p < 0.05) and abnormal in 80% of the HI patients. A prolonged GET1/2 and higher incidence of abnormal GET1/2 were observed in female patients, older patients, and patients with low Glasgow coma scale (GCS) scores, when compared with male patients, younger patients, and patients with high GCS scores. However, the differences for the means of GET1/2 and the incidences of abnormal GET1/2 between the subgroup patients were not significant (p >0.05). In addition, significantly prolonged GET1/2 and higher incidence of abnormal GET1/2 (p < 0.05) were observed in patients with short injury duration, in comparison with patients with long injury duration.Conclusion:Head injury can cause significant prolonged GE of liquid meals, especially in patients with short injury duration.

Detection of recurrent or persistent nasopharyngeal carcinomas after radiotherapy with 18-fluoro-2-deoxyglucose positron emission tomography and comparison with computed tomography.

PURPOSE The effectiveness of positron emission tomography (PET) with 1 8-fluoro-2-deoxyglucose (FDG) for detecting suspected recurrence of nasopharyngeal carcinomas (NPC) was evaluated and compared with computed tomography (CT). PATIENTS AND METHODS FDG-PET studies were performed on 36 NPC patients 4 months after radiotherapy. The images were interpreted visually and quantitatively by calculating standardized uptake values (SUVs). RESULTS The sensitivity, specificity, and accuracy of visually interpreted FDG-PET images, for differentiation of recurrent or persistent NPC from benign lesions, were 100%, 96%, and 97%, respectively. Cases with recurrent or persistent NPC (1.6 to 5.8) had significantly higher SUVs than cases with benign lesions (0.8 to 1.5). The sensitivity, specificity, and accuracy of CT for detecting recurrent or persistent NPC were 72%, 88%, and 83%, respectively. CONCLUSION FDG-PET is a better tool than CT for the detection of recurrent or persistent NPC. Either visual interpretation or SUV can be used to differentiate benign lesions from recurrent or persistent NPC.

Discrepancy between regional cerebral blood flow and glucose metabolism of the brain in systemic lupus erythematosus patients with normal brain magnetic resonance imaging findings.

OBJECTIVE In this study, 2 updated brain-imaging modalities, technetium-99m hexamethylpropylene amine oxime-single-photon-emission computed tomography (HMPAO-SPECT) and fluorine-18 2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET), were used to simultaneously detect regional cerebral blood flow (rCBF) and glucose metabolism of the brain in patients with systemic lupus erythematosus (SLE). METHODS Twenty-five female SLE patients, ages 25-40 years, were enrolled in this study and assigned to 1 of 2 groups. Group 1 consisted of 13 patients with neuropsychiatric manifestations (7 had major and 6 had minor manifestations). Group 2 consisted of 12 patients without neuropsychiatric manifestations. Serum levels of anticardiolipin antibodies (aCL) and anti-ribosomal P antibodies (anti-P) were measured. All patients had normal brain magnetic resonance imaging (MRI) findings. Ten healthy female volunteers also underwent brain MRI, HMPAO-SPECT, and FDG-PET for comparison. RESULTS 99mTc-HMPAO-SPECT revealed hypoperfusion lesions in 11 (44%) of 25 SLE patients, including 9 (69%) of the 13 patients in group 1, 7 (100%) of the 7 patients with major manifestations, 2 (33%) of the 6 patients with minor manifestations, and 2 (17%) of the 12 patients in group 2. Parietal lobes were the areas most commonly involved. FDG-PET revealed hypometabolism in 7 (54%) of the group 1 patients, 6 (86%) of the 7 patients with major manifestations, and 1 (17%) of the 6 patients with minor manifestations. Temporal lobes were the most commonly involved areas. However, no significant hypometabolism brain lesions were found in group 2 patients. All of the 4 patients with headaches and dizziness or headaches alone had normal findings on HMPAO-SPECT and FDG-PET. Nine (36%) of the 25 patients were positive for aCL. However, the presence of aCL was not related to neuropsychiatric manifestations or to HMPAO-SPECT or FDG-PET findings. Five (20%) of the 25 patients had anti-P antibodies and psychosis/depression. CONCLUSION In patients with normal brain MRI findings, decreases in glucose metabolism coupled with decreases in rCBF are associated with serious neuropsychiatric SLE (NPSLE) presentations, while normal glucose metabolism with decreases in rCBF may be found in SLE patients with or without NPSLE.

Assessment of coronary artery disease in women by dobutamine stress echocardiography: Comparison with stress thallium-201 single-photon emission computed tomography and exercise electrocardiography

BACKGROUND Dobutamine stress echocardiography (DSE) is sensitive and specific in detecting myocardial ischemia of male patients. However, there have been few reports about the use of DSE for the detection of coronary artery disease (CAD) in women. METHODS DSE was evaluated in 51 consecutive women who underwent concomitant quantitative coronary angiography. Forty-four of the 51 patients received stress thallium-201 single-photon emission computed tomography (SPECT), and 30 of the 51 patients had interpretable results (exercise level > or = 85% of age-predicted maximal heart rate) of treadmill exercise. Twenty-nine patients had angiographically documented CAD defined as > or = 50% diameter stenosis. RESULTS The overall sensitivity of DSE and stress 201Tl SPECT in detecting CAD was 93% and 79% (p = nonsignificant), and the specificity was 82% and 75% (p = nonsignificant), respectively. A combination of both tests increased the sensitivity (96%) at the expense of some decrease in specificity (60%). The agreement of DSE and 201Tl SPECT was 68% (30 of 44; kappa statistic = 0.35; p < 0.0001). The overall sensitivity, specificity, and accuracy in detecting CAD by treadmill exercise test and DSE were 71% vs 93% (p = nonsignificant), 44% vs 82% (p = 0.036), and 57% vs 88% (p = 0.003). In patients with abnormal results of treadmill exercise testing, the false-positive rate in detecting CAD was 2 (18%) of 11 in patients with abnormal results of DSE and 7 (88%) of 8 in those with normal results of DSE (p = 0.005). In patients with normal results of treadmill exercise testing, the false-negative rate in detecting CAD was 4 (100%) of 4 in patients with abnormal results of DSE and 0 (0%) of 7 in those with normal results of DSE (p = 0.003). CONCLUSION The diagnostic accuracy of DSE was similar to that of stress 201Tl SPECT in women. DSE was able to stratify female patients with either abnormal or normal results of treadmill exercise testing and to avoid unnecessary cardiac catheterization.

Prevalence of vertebral fractures in chinese men and women in urban Taiwanese communities.

Abstract. Reports on the prevalence (or incidence) rates of vertebral fracture have been available, but they are limited concerning non-white populations and men of all races. This study used the radiomorphometric method to survey the prevalence rate of vertebral fracture for ethnic Chinese women 40 years and older and Chinese men 65 and older who were randomly selected from four major cities in Taiwan. Three sets of reference values of the height ratios were used for middle-aged women, elderly women, and elderly men. The results showed that in Chinese women, the prevalence rate of vertebral fracture was low before age 50 and showed a steady increase thereafter. In men, the increase was small until age 80. The overall adjusted prevalence rate of vertebral fracture for women older than 65 was 20% and that for men, 12.5% (95% confidence interval 18–22% and 11–14%, respectively.) If only severe deformity was counted [height ratio lower than normal mean minus 4 standard deviations (SD), or Grade II deformity], the adjusted prevalence rate was 15.5% for elderly women and 9.5% for elderly men (95% confidence interval 14–17%, and 8–11%, respectively.) The overall adjusted prevalence rate for women aged 40 and over was 6.8% (95% confidence interval 5.7–8%), or 4.5% (95% confidence interval 3.6–5.5%) for Grade II lesions. Moreover, for subjects with fracture, elderly women tended to have more fractured vertebrae per person and more Grade II fractures than elderly men. Thus, Chinese women residing in cities of Taiwan had a relatively high prevalence rate of vertebral fracture, a finding compatible with that for United States or European white women, or for Japanese women residing in America. Elderly Chinese men also have a high prevalence rate of vertebral fracture. The age-specific female-to-male ratio of prevalence rate was about 1.5 to 2.3 between age 65 and 80, and close to unity after age 80.

The role of FDG-PET, HMPAO-SPET and MRI in the detection of brain involvement in patients with systemic lupus erythematosus.

Abstract. Involvement of the brain is one of the most important complications of systemic lupus erythematosus (SLE); however, its diagnosis is difficult due to the lack of effective imaging methods. We combined three brain imaging modalities – positron emission tomography with fluorine-18 2-fluoro-2-deoxy-d-glucose (FDG-PET), single-photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime (HMPAO-SPET) and magnetic resonance imaging (MRI) – in order to detect brain involvement in SLE. Thirty-seven SLE patients, aged 22–45 years, were divided into three groups. Group 1 (G1) consisted of ten patients with major neuropsychiatric manifestations; group 2 (G2) consisted of 15 patients with minor manifestations; and group 3 (G3) consisted of 12 patients without manifestations. FDG-PET findings were abnormal in 51% of patients: 90% of G1, 67% of G2 and 0% of G3 patients respectively. HMPAO-SPET findings were abnormal in 62% of patients: 100% of G1, 73% of G2 and 17% of G3 patients respectively. MRI findings were abnormal in 35% of patients: 70% of G1, 40% of G2 and 0% of G3 patients respectively. Grey matter was more commonly involved than white matter; 62% of patients presented with lesions in the cerebral cortex, 27% with lesions in the basal ganglion, 5% with lesions in the cerebellum, and 19% with lesions in white matter. No white matter lesions were found on FDG-PET or HMPAO-SPET. However, in 19% of patients, MRI demonstrated abnormally high signal lesions in white matter. Forty-three percent of cases had positive serum anticardiolipin antibodies (ACA). However, ACA was not related to FDG-PET, HMPAO-SPET or MRI findings. It may be concluding that HMPAO-SPET is a more sensitive tool for detecting brain involvement in SLE patients when compared with FDG-PET or MRI. However, MRI is necessary for detecting lesions in white matter.

Bone mineral density and bone markers in relation to vitamin D receptor gene polymorphisms in Chinese men and women

Whether vitamin D receptor gene (VDRG) polymorphism can be used as a predictor for bone turnover rate or bone mass remains controversial. Its role within various ethnic populations are also unsettled. We examined VDRG polymorphism using restrictive enzymes Bsm-I, Apa-I, and Taq-I in 155 men aged 22-88 and 113 premenopausal women aged 40-53. The bone mineral density (BMD) of the vertebrae (L2-4), proximal femur, and total body bone mineral content (tb-BMC) (women only), as well as urinary N-terminal crosslinked fragment of type I collagen (NTX), serum osteocalcin, bone isozyme of alkaline phosphatase, and caboxyterminal propeptide of type I procollagen levels were measured. Chinese men and women exhibited a low prevalence for B (absence of Bsm-I restriction site) phenotypes than white and Japanese. Within the tested samples there were 0.4% BB homozygotes, 6.7% Bb heterozygotes, and 93% bb homozygotes. The distributions of Apa-I polymorphism (9.0% AA, 42.5% Aa, and 48.5% aa) also differed from those reported for the white populations. Most of the Chinese men and women were TT homozygous (96.6%). A comparison of actual values and values adjusted for age and weight of tb-BMC and BMD at the lumbar spine, Trochanter, Wards triangle, and femoral neck showed no significant difference among three subgroups in each of the three sets of polymorphism. Furthermore, the actual values and adjusted values (adjusted for age) of the four bone markers, respectively, showed no significant differences. We conclude that given the very low prevalence of the suspected high risk genotypes (B, A, and t), and the lack of difference among the polymorphic subgroups, VDRG polymorphism may not be an important determinant of the bone turnover rate and bone mass of Chinese men and women.

Sexual differences in bone markers and bone mineral density of normal Chinese

We measured bone mineral density (BMD) at lumbar (L2–L4) vertebrae and proximal femurs of 385 healthy Chinese women aged 40–70 years and 156 healthy Chinese men aged 20–85, and four markers—bone alkaline phosphatase isozyme (BAP), procollagen-I C terminal propeptide (PICP), osteocalcin (BGP) in serum, and a bone resorption marker, urinary cross-linked N-telopeptide of type I collagen (NTX), of these subjects. The results indicate that in postmenopausal women, levels of all the markers increased with age. In men, serum BAP, PICP, and urinary NTX decreased significantly, and serum BGP decreased with borderline significance (P=0.08). With increasing age, bone density decreased at both sites in post-menopausal women and at the proximal femur in men. The lumbar bone density showed no significant age-related changes in men. In premenopausal women, BMD at either site showed no significant change with increasing age. Despite the different trends between men and women of agerelated changes in BMD and bone markers, bone density of both proximal femur and spine in both sexes correlated inversely with levels of the bone markers in a manner independent of age or body weight. The meaning of opposite age effects on bone markers in men and women needs further investigation. In addition, higher bone marker levels, implying faster bone turnover rate, are associated with lower BMD in both sexes.

Bone mineral density of normal Chinese women in Taiwan

SummaryBone mineral density (BMD) may be different in different ethnic groups. To determine BMD and the effect of aging and body weight upon it in healthy Chinese women living in the Taipei urban area, we measured BMD of 116 healthy women aged 18–80 years using a commercially available dual photon absorptiometer (DPA).The BMD of the lumbar spine (L2–L4) remained relatively constant and had a mean value of 1.12 g/cm2 at age 20–49 years; it then decreased significantly from age 50 and up in a linear fashion with an apparent slope of about 0.01 g/cm2/year. The BMD of the total body skeleton showed a similar pattern. The trend and the absolute BMD values of the lumbar spine at all ages are similar to those previously reported for a U.S. white population. However, the BMD at the hip region revealed levels of about 10–15% lower than what was reported for a U.S. white population and was comparable to the femoral neck BMD of Japanese women measured with the same machine. The correlation among the BMDs at different sites for each subject was significant (r=0.72–0.8), but the BMD measured at a single site cannot be used to predict the BMD found at the other sites because of the substantial variation. The stepwise regression analysis showed that both age and body weight influenced BMD. Our data suggest that Chinese women are not at less risk for osteoporotic fractures, and that body weight contributes to the BMD measured at specific sites in our population even when the overtly obese subjects were excluded.

Comparison of 18-Fluoro-2-Deoxyglucose Positron Emission Tomography and Computed Tomography in Detection of Cervical Lymph Node Metastases of Nasopharyngeal Carcinoma

Neck lymph nodes (LNs) from 18 patients with nasopharyngeal carcinoma (NPC) were evaluated with 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET). Eighteen NPC patients underwent head and neck FDG-PET and computed tomography (CT) for detection of suspected neck LN metastases. For final diagnosis, biopsies were taken from neck LNs with discordant findings between FDG-PET and CT. Meanwhile, standard uptake values (SUVs) of the FDG-PET images were calculated to differentiate metastatic LNs from benign LNs. A total of 90 neck LNs found on either FDG-PET or CT were evaluated. In addition to 27 concordant positive results and 42 concordant negative LN results, biopsy findings revealed 11 metastatic LNs that were detected by FDG-PET but not by CT. However, the SUVs of the 11 metastatic LNs and 7 benign LNs were not significantly different. The CT scanning showed positive findings for 1 metastatic LN with negative FDG-PET findings. In addition, the tumor stage was upgraded in 5 patients on the basis of FDG-PET findings. In comparison with CT, FDG-PET has a higher potential for detecting neck LN metastases of NPC and assessing NPC tumor stage.