Vascular defect beyond the endothelium in type II diabetic patients with overt nephropathy and moderate renal insufficiency.

There is a paucity of data on the effects of overt nephropathy and moderate renal impairment on endothelial function in diabetic patients. A total of 26 type II diabetic (DM) patients with nephropathy (DMN+) (mean +/- s.d. age: 63.7 +/- 6.3 years), 32 diabetic patients without nephropathy (DMN-) (59.4 +/- 10.1 years), and 52 non-diabetic subjects (54.9 +/- 8.2 years) were recruited. High-resolution ultrasound scan was used to measure carotid intima media thickness (IMT) and flow-mediated dilation (FMD) of the brachial artery. Endothelium-independent dilation was determined by maximal vascular dilation after sublingual nitroglycerine (glyceryl trinitrate (GTN)-induced dilation). The mean carotid IMT increased progressively from non-DM to DMN- to DMN+ groups (0.74 +/- 0.23 vs 0.80 +/- 0.25 vs 1.03 +/- 0.38 mm; P=0.001 for trend) whereas FMD- (4.3 +/- 2.5 vs 3.9 +/- 1.7 vs 1.9 +/- 2.0%, P<0.001 for trend) and GTN-induced dilation (14.7 +/- 4.0 vs 14.5 +/- 3.9 vs 10.3 +/- 3.2%; P<0.001 for trend) declined in an opposite manner. On multivariate analysis, age (beta=0.257, P=0.009), glomerular filtration rate (beta=-0.364, P<0.001), and smoking (beta=0.25, P=0.013) were independently associated with carotid IMT (F=15.76, R(2)=0.340, P<0.001). After adjustment for baseline brachial arterial diameter, history of smoking (beta=-0.039, P<0.001), fasting plasma glucose (beta=-0.033, P=0.002), and total cholesterol (beta=-0.023, P=0.024) were independently associated with vessel diameter after FMD (F=2446.5, R(2)=0.992, P<0.001); whereas age (beta=-0.069, P=0.001) and urinary albumin excretion (beta=-0.048, P=0.018) were independently associated with vessel diameter after GTN (F=851.6, R(2)=0.967, P<0.001). Type II diabetic patients with overt nephropathy and moderate renal impairment had both structural and functional vascular abnormalities beyond the endothelium.

Potential value of post stroke extracranial arterial blood flow volume in the prediction of stroke functional outcome.

BACKGROUND AND PURPOSE: Cerebral vasoreactivity and collateral circulation are important protective mechanisms against cerebral ischemia. Previous studies suggest that the efficiency of these mechanisms can be reflected by extracranial arterial blood flow volume. Brain damage leading to neurological impairments can influence patients' functional recovery after stroke. This study attempted to explore the potential value of post stroke extracranial arterial blood flow volume in the prediction of stroke patients' functional outcome. METHODS: We prospectively studied 362 consecutive patients who were hospitalized for recent acute strokes. All patients underwent extracranial arterial blood flow volume measurement of the carotid and vertebral arteries by color velocity imaging quantification within 3 days after admission. Their functional recovery was assessed 6 months after stroke. The effect of post stroke extracranial arterial blood flow volume on patients' functional outcome was tested by multivariate ordinal regression after controlling for other independent variables. Significance was at p<0.05. RESULTS: Post stroke extracranial arterial blood flow volume together with age, pre-stroke modified Rankin scale, the National Institutes of Health Stroke Scale and diabetes mellitus had significant effects on the patients' 6-month functional outcome as measured by the modified Rankin scale after controlling for other independent variables (p<0.05). CONCLUSIONS: Post stroke extracranial arterial blood flow volume is an independent outcome predictor. The graded predictive power of this parameter is potentially more superior than other outcome predictors by allowing classification of stroke outcome according to the degree of severity. A large prospective study is thus warranted to investigate its clinical value in the management of stroke patients.

Duplex ultrasound screening for deep vein thrombosis in Chinese after cesarean section.

BACKGROUND: To evaluate the incidence of asymptomatic deep vein thrombosis (DVT) in Chinese after cesarean section (CS). METHODS: This is a prospective observational study. Ethnic Chinese women who were asymptomatic for DVT and delivered by CS were included. Duplex ultrasound scan (US) of the lower limbs was carried out 3-7 days after CS. RESULTS: From July 2000 to March 2001, a total of 93 women were examined. The mean age was 32.1 years (SD 5.0). Forty-nine of 93 CSs were elective (52.7%). The median time from CS to US was 4 days (interquartile range, 4-5 days). No case of DVT was found in these 93 women. CONCLUSION: The incidence of asymptomatic DVT is low in Chinese women after CS. Routine screening for DVT after CS is not warranted.

Cerebral vasoreactivity: a comparison of color velocity imaging quantification and stable xenon-enhanced CT.

OBJECTIVE: Compromised cerebral vasoreactivity increases the risk of stroke. In this study, we sought to determine whether extracranial arterial blood flow volume measured on color velocity imaging quantification could be predictive of cerebral vasoreactivity after the administration of acetazolamide. SUBJECTS AND METHODS: Cerebral blood flow and extracranial arterial blood flow volume of 35 patients with symptomatic carotid occlusive disease were measured before and after the administration of acetazolamide on stable xenon CT and color velocity imaging quantification, respectively. The changes in unilateral extracranial arterial blood flow volume and respective hemispheric cerebral blood flow were compared. The mean difference in the percentage of change in flow volume, the 95% limit of agreement, and Cohen's kappa coefficient were calculated. RESULTS: A total of 64 unilateral extracranial arterial blood flow volume changes were successfully compared with the changes in the ipsilateral hemispheric cerebral blood flow. The mean difference in percentage of change in flow volume between the two techniques was 4.7%, with the 95% limit of agreement ranging from -90.2% to 99.7%. Cohen's kappa coefficient was 0.41 (95% confidence interval, 0.13-0.68; p = 0.001). CONCLUSION: The performance of color velocity imaging quantification for evaluating cerebral vasoreactivity is comparable to that of transcranial Doppler sonography. Because color velocity imaging quantification is not as limited as transcranial Doppler sonography, it could be an ideal complementary tool to transcranial Doppler sonography. More studies are required to define its clinical value.

Magnetic resonance coronary angiography with 3D TrueFISP: breath-hold versus respiratory gated imaging.

To compare the diagnostic accuracy of coronary magnetic resonance angiography with three-dimensional (3D) trueFISP breath-hold and respiratory gated techniques for the detection of significant coronary artery stenosis. 15 patients who recently underwent elective coronary angiogram were studied and a total of 60 arteries and 48 arteries were assessed by breath-hold and respiratory gated 3D trueFISP techniques, respectively. The image quality, length of artery visualized and the presence or absence of significant coronary artery stenosis were recorded. 83.3% and 81.7% of the arteries obtained with the respiratory gated and the breath-hold techniques, respectively, had an image quality suitable for further analysis. There was no significant difference in the length of artery visualized. Sensitivity and specificity of 80%, 100% and 75% and 100%, respectively, were obtained with the breath-hold and respiratory gated techniques in detecting significant stenosis in the coronary arteries. Both techniques have moderate sensitivity and high specificity in detection of significant stenosis in the visualized segments of the major coronary arteries. However, they cannot replace conventional coronary angiogram for diagnosing coronary artery disease at present. Further studies are required to evaluate whether breath-hold approach is more efficient, therefore should be performed first and respiratory gated approach reserved for those who cannot breath-hold.

Magnetic resonance cholangiography in children.

Magnetic resonance cholangiography has been shown to be useful in the evaluation of hepatobiliary problems in paediatric patients. Its clinical application in biliary atresia, choledochal cyst, cholelithiasis, bile plug syndrome and liver transplant are illustrated by the following cases.

Overweight in children is associated with arterial endothelial dysfunction and intima-media thickening.

OBJECTIVE: We sought to study arterial endothelial function and carotid intima-media thickness (IMT), both early markers of atherosclerosis, in overweight compared to normal children. DESIGN: Case-control comparison. SUBJECTS: A total of 36 asymptomatic overweight children (body mass index (BMI)>23; mean 25+/-3) aged 9-12 y and 36 age- and gender-matched nonobese healthy children (BMI<21) from a school community. MEASUREMENTS: The key parameters were: BMI, arterial endothelial function (ultrasound-derived endothelium-dependent dilation) and carotid artery IMT. The secondary parameters measured included body fat content, waist-hip ratio (WHR), blood pressures, blood lipids, insulin and glucose. RESULTS: The two groups were well matched for blood pressures, cholesterol and glucose levels, but BMI (P<0.0001), body fat (P=0.001), WHR (P<0.05), fasting blood insulin (P=0.001) and triglyceride levels (P<0.05) were higher in obese children. Overweight was associated with impaired arterial endothelial function (6.6+/-2.3 vs 9.7+/-3.0%, P<0.0001) and increased carotid IMT (0.49+/-0.04 mm vs 0.45+/-0.04 mm, P=0.006). The degree of endothelial dysfunction correlated with BMI (P<0.003) on multivariate analysis. CONCLUSION: Obesity, even of mild-to-moderate degree, is independently associated with abnormal arterial function and structure in otherwise healthy young children.

Ultrasound bladder measurements in patients with primary nocturnal enuresis: a urodynamic and treatment outcome correlation.

PURPOSE: Accurate assessment of bladder dysfunction associated with voiding dysfunctions often necessitates invasive urodynamic (UD) studies. We evaluate the use of a special ultrasound (US) protocol for the assessment of bladder dysfunction compared with urodynamic findings, and for prediction of treatment outcome in children with primary nocturnal enuresis (PNE). MATERIALS AND METHODS: US measurements were performed on 514 children 5 to 18 years old (mean age 11.2) with PNE, and compared with those of 339 normal age matched children. A US protocol was specially designed for the evaluation of bladder parameters using bladder volume and wall thickness index (BVWI %), and expected percentage bladder volume index for kidney volume. Of the enuretic children 218 had severe enuretic symptoms with more than 3 wet nights a week. They underwent urodynamic studies for detailed assessment of any underlying bladder dysfunction. A standard 4-week course of desmopressin was given to these children after the US and UD studies. The US bladder parameters were then correlated with the UD findings and treatment response to desmopressin. RESULTS: Comparing the BVWI in normal and enuretic children in correlation with functional bladder capacities we were able to delineate bladder wall thickness and capacity as BVWI less than 70-small capacity bladder with thick wall, BVWI 70 to 130-normal bladder capacity with normal wall thickness and BVWI greater than 130-large bladder capacity with thin wall. There were statistically significant correlations between BVWI and treatment response. In addition, there was a high predictive value of normal bladder function with a normal BVWI. Patients with good response to treatment had normal BVWI, whereas poor response to treatment was significantly associated with pathological bladder conditions, that is small bladder capacity with thick bladder wall or large bladder capacity with thin bladder wall (p <0.0001). Of note, abnormalities detected by UD correlated well with bladder abnormalities measured by US. CONCLUSIONS: PNE comprises a diverse spectrum of conditions resulting in a mismatch of nocturnal urine production in excess of nocturnal functional bladder capacity, and underlying bladder dysfunction has an important role in the pathophysiology especially in refractory cases. This US protocol can provide useful predictive clues, which may be helpful to differentiate treatment subtypes, guide clinical management and minimize the need for invasive urodynamic studies.

Magnetic resonance imaging in ischaemic heart disease.

Magnetic resonance imaging has an increasing role in the assessment of ischaemic heart disease. Its superb spatial and temporal resolution currently allows accurate assessment of cardiac function, regional wall motion, and the extent of myocardial infarction. Regional myocardial perfusion can also be assessed, most commonly by a first-pass technique. Non-invasive imaging of the coronary arteries by various magnetic resonance imaging techniques represents a major advance in recent years. In the foreseeable future, magnetic resonance imaging may become a single, comprehensive examination for the assessment of ischaemic heart disease.

Feasibility study of using air as a contrast medium in MR colonography.

AIM: To evaluate the feasibility of using air as intraluminal contrast medium in magnetic resonance (MR) colonography. MATERIALS AND METHODS: Twenty-two patients underwent MR colonography (MRC) using air before colonoscopy. All patients were imaged in prone and supine positions. Each colon was divided into five segments. Two radiologists reviewed the images for the degree of colonic distension, image quality and colonic lesions. The colonic lesions identified using MR were compared with those identified on colonoscopy. RESULTS: Eight men and 14 women with mean age of 55.5 years were studied. All patients completed the MR examination. One hundred and five out of 110 (95.5%) colonic segments were well distended in both prone and supine positions. Image quality was good in all cases. Colonoscopy detected 16 lesions: three > or = 1 cm, one 7 mm lesion and 12 lesions < or = 5 mm. All lesions 1 cm or larger were detected by MRC. CONCLUSION: MRC using air and the single-shot half-Fourier rapid acquisition with refocused echoes (RARE) technique is feasible. But in this small pilot study, it had low sensitivity for the detection of polyps less than 1 cm in diameter.

Hyperintense middle cerebral artery sign using MRI.

AIM: To assess whether the presence of the hyperintense middle cerebral artery (MCA) sign, detected using magnetic resonance imaging (MRI), has any prognostic value in subacute infarction. The results were also compared with computed tomography (CT). MATERIALS AND METHODS: Twenty-five consecutive patients with suspected subacute ischaemic stroke (6-48 h after onset of symptoms) underwent MRI and CT assessment. The incidence of intraluminal thrombus demonstrated by conventional T1 and T2-weighted images was assessed. The results were correlated with National Institutes of Health Stroke Scale (NIHSS). RESULTS: Hyperintense MCA was identifiable on T1-weighted images in 77.8% patients, on T2-weighted images in 61.1% patients, and in 38.9% patients using CT. Patients with intraluminal thrombus identified by MRI had more severe stroke (mean NIHSS of 12.2+/-8.0 versus 4+/-3.2 respectively, p=0.003). CONCLUSIONS: The presence of hyperintense MCA by MRI is associated with higher NIHSS and may therefore have a prognostic value.

Back pain in pregnancy--magnetic resonance imaging correlation.

AIM: To study the relationship of disk abnormality and signal changes of the uterine cervix on magnetic resonance imaging (MRI) with back pain in pregnancy at 36-39 weeks of gestation. MATERIAL AND METHODS: One hundred and five pregnant Chinese women with previous Caesarean section at 36-39 weeks gestation undergoing magnetic resonance pelvimetry performed for a study for trial of vaginal delivery were questionnaired for back pain. Sagittal T2-weighted images were analysed for intervertebral disk abnormality, and signal intensity of the uterine cervix on the same sagittal images. The findings on MRI were correlated with back pain. RESULTS: Seventy-three (70%) of the pregnant women had back pain. Disk bulge or prolapse were infrequent but correlated significantly with the presence of back pain (P=0.02). Women with back pain in the current pregnancy tended to have a higher signal intensity of the uterine cervix compared with those without (P=0.006). Women with a history of back pain also had higher cervical signal intensity compared with those without (P=0.02). CONCLUSION: Disk bulge or prolapse was associated with back pain in pregnancy but were relatively infrequent. The significant correlation of high signal intensity in the uterine cervix and back pain suggested that soft tissue laxity may be a more important cause of back pain in pregnancy than disk bulge or prolapse.

Mature teratomas of the adrenal gland: imaging features.

BACKGROUND: We describe the imaging features of three, histologically confirmed, mature teratomas of the adrenal gland not described previously in the radiologic literature and discuss the differential diagnosis of lipomatous tumors of the adrenal gland. METHODS: Computed tomographic (n = 3), magnetic resonance imaging (n = 1), and sonographic (n = 1) features were reviewed retrospectively and the findings correlated with gross pathology and histology. RESULTS: There were two females (age 8 and 18 years) and one male (age 17 years). Tumor size ranged from 5 to 11 cm (mean = 7.3 cm). All tumors were well circumscribed and contained fat components. Calcification was demonstrated in two tumors and was the predominant component in one. Only one was cystic. CONCLUSION: The radiologic features of these tumors were typical of mature teratomas occurring elsewhere in the body. This should be considered in the differential diagnosis of lipomatous tumors of the adrenal gland, especially in children and adolescents.

Color velocity imaging quantification in the detection of intracranial collateral flow.

BACKGROUND AND PURPOSE: The development of intracranial collateral circulation is associated with a lower risk of stroke. A noninvasive technique that can reliably detect the presence of intracranial collaterals would be a valuable factor in the assessment of risk in patients with occlusive cerebrovascular disease. METHODS: Color velocity imaging quantification was used to measure the blood flow volume of the common carotid and vertebral arteries in 40 patients with carotid occlusive disease. The blood flow volumes in these arteries were correlated with angiographic evidence of collaterals to establish the best cutoffs for detecting intracranial collateral circulation. RESULTS: A blood flow volume of either > or =370 mL/min in the common carotid artery or > or =120 mL/min in the vertebral artery was indicative of the presence of intracranial collaterals. The sensitivity and specificity for the common carotid artery were 92.3% [95% confidence interval (CI), 62.1 to 99.6] and 92.1% (95% CI, 77.5 to 97.9), respectively. The sensitivity and specificity for the vertebral artery were 75.0% (95% CI, 35.6 to 95.5) and 87.5% (95% CI, 66.5 to 96.7), respectively. CONCLUSIONS: Color velocity imaging quantification offers a noninvasive, accurate method for detecting the presence of intracranial collateral circulation and quantifying its magnitude. This technique would be a useful adjunct in screening or continuous monitoring of patients with severe carotid occlusive disease.

Carotid intima-media thickness in patients with head and neck irradiation for the treatment of nasopharyngeal carcinoma.

AIM: Intima-media thickness (IMT) has been shown to be useful in the evaluation and monitoring of carotid artery atherosclerosis in patients at risk of cardiovascular events. In this study, we aimed to examine the IMT in patients with nasopharyngeal carcinoma (NPC) who received irradiation to the carotid arteries during radiotherapy, and compared them with a control group. MATERIALS AND METHODS: Fifty-one NPC patients (aged between 39 and 69 years) and a group of 51 age-and sex-matched controls were studied by ultrasound. The IMT at the far wall of the common carotid artery was measured three times and the average value taken in each subject. The IMT of both groups were compared. Risk factors for IMT thickness, including hypertension, smoking, hyperglycaemia, hypercholesterolaemia, history of cerebrovascular accidents and cardiovascular disease, were also studied. RESULTS: The mean carotid IMT of patients in the NPC group (2.2+/-1.5 mm) was statistically greater than that in normal controls (0.7+/-0.15 mm) (P < 0.05). There was no statistically significant difference between the IMT in the right and left common carotid arteries within each group of patients. CONCLUSION: The findings suggest that patients with irradiation have increased arterial IMT. As they are asymptomatic the clinical relevance is not clear.

Ectopic thymic tissue in the paediatric age group.

PURPOSE: The presence of ectopic thymic tissue is well known along the embryological descent track in the neck. The aim of this study was to detect the frequency of cervical thymic rests in children. MATERIAL AND METHODS: Eighteen consecutive children had neck US performed using an ATL 5000 unit with a 12.5 MHz liner probe. The presence of small rests of thymic tissue was sought. RESULTS: 61% of the children had thymic tissue detected in the neck. Out of those with positive findings, 82% had a thymic rest on the right side, 9% on the left side and 9% had thymic rests bilaterally. CONCLUSION: Small rests of ectopic thymic tissue in the cervical region are commonly seen in the paediatric age group. It is important to identify the thymic rests for what they are and avoid unnecessary anxiety or intervention.

Diffusion MR imaging in glioma: does it have any role in the pre-operation determination of grading of glioma?

AIM: To investigate the role of the diffusion MR weighted sequence in the pre-operative grading of gliomas, and its application in defining the different components of these tumours. MATERIALS AND METHODS: Seventeen patients with gliomas (eight high grade, nine low grade) had diffusion weighted imaging. Apparent diffusion coefficients (ADCs) of different components of tumours were measured. RESULTS: ADC of the cystic portion of the tumour was significantly higher than ADCs of the enhanced tumour, non-enhanced tumour and perifocal oedema (P < 0.01). No significant difference in ADC values between low grade and high grade glioma (P > 0.7) was found nor was there any difference between oligoglioma and non-oligoglioma (P > 0.29). CONCLUSION: ADC value was useful to differentiate the cystic from the solid components of the tumours. However, it was not useful in pre-operative grading of glioma.

Extranodal manifestation of Kimura's disease: ultrasound features.

We describe the imaging features of a 53-year-old Chinese patient with Kimura's disease (KD) who presented with a dominant right-cheek subcutaneous mass. The lesion appeared as an ill-defined mass within the subcutaneous tissues with a "wooly" echotexture on US. The differential diagnosis and a review of the literature are discussed.

Sonographic characterisation of radiation-induced carotid artery stenosis.

BACKGROUND AND PURPOSE: To study the distribution, extent and sonographic characterisation of radiation-induced carotid artery stenosis in nasopharyngeal carcinoma (NPC) patients. METHODS: The distribution of plaques, the extent of stenosis, and the sonographic characterisation of the plaque at maximum stenosis were recorded in 71 NPC patients. The results were compared with the ultrasound results of a control group of 142 patients presenting with symptoms of cerebrovascular disease or carotid bruit. RESULTS: NPC patients had a higher incidence of carotid stenosis (77 vs. 50.7%). The common carotid arteries were most commonly affected by radiation-induced stenosis (93/142 vs. 37/284 in the control group), whereas the carotid bulb was the most commonly affected (56/284) site in the control group. Significantly more NPC patients had moderate-to-severe stenosis (21/71 vs. 27/142). Analysis of the sonographic appearance of radiation-induced and atherosclerotic plaques showed more diffuse involvement in the post-radiation group. Non-calcified plaques and intraplaque hypoechoic foci were also more frequent in the post-radiation group. CONCLUSIONS: Radiation-induced carotid stenosis is more diffuse in distribution, is associated with more severe luminal stenosis and has different sonographic plaque characterisation compared with carotid stenosis without radiation exposure.

Biliary drainage for obstructive jaundice enhances hepatic energy status in humans: a 31-phosphorus magnetic resonance spectroscopy study.

BACKGROUND: Biliary obstruction impairs liver function although the pathophysiological mechanism is incompletely understood. AIMS: The aim of this study was to examine serial changes in liver metabolism in patients with obstructive jaundice using image guided in vivo 31-phosphorus magnetic resonance spectroscopy ((31)P MRS). This technique allows repeated and non-invasive assay of organ energy metabolism and phospholipid biochemistry. PATIENTS: We studied 10 patients presenting with obstructive jaundice secondary to extrahepatic localised malignancy. There were eight men and two women, median age 72 years (range 54-94), six with cholangiocarcinoma (all Bismuth type 1) and four with carcinoma of the head of the pancreas. Ten healthy volunteers (median age 24 years (range 21-26)) were studied for comparison. METHODS: Hepatic metabolism in jaundiced patients was measured by (31)P MRS at presentation and again after a one week period of biliary drainage. Conventional liver function tests were also recorded. RESULTS: Compared with controls, liver spectra from jaundiced patients contained an excess of phosphomonoester (PME) metabolites (PME/total phosphate median 10.3% (interquartile range 8.7-11.5) in controls, 15.4% (13.1-17.7) in jaundiced cases; p<0.01). Biliary decompression was achieved in all patients (five with internal stents and five by external drainage catheters), and plasma biochemistry improved predictably (bilirubin 176 micromol/l (158-351) at presentation, 110 micromol/l (42-241) after drainage for one week; p<0.01). Enhancement of hepatic energy status, measured by the ratio of adenosine triphosphate (ATP) to inorganic phosphate (Pi), was observed in all cases after relief of biliary obstruction (ATP/Pi 1.4 (1.17-1.69) at presentation, 1.97 (1.4-2.48) after drainage; p<0.01) and was independent of the route of bile drainage. Hepatic phosphodiester (PDE) content was decreased after relief of obstruction (PDE/total phosphate 25.2% (20.5-27.4) at presentation, 19.8% (16.6-24.5) after drainage; p<0.01). This change was probably due to a reduction in the contribution from bile contents to this resonance as a strong PDE signal was also detectable in spectra obtained from separate bile specimens. CONCLUSIONS: Obstructive jaundice produces alterations in liver phosphoester biochemistry, most likely reflecting disturbances in phospholipid metabolism. Relief of biliary obstruction is associated with a measurable increase in hepatic energy status. Bile may contribute to the phosphodiester signal of the 31-phosphorus liver spectrum and changes in these resonances must therefore be interpreted with caution and in relation to the clinical situation. Monitoring of liver metabolism by (31)P MRS may allow clinicians to refine the selection and timing of therapeutic options in jaundiced patients.