Biomedical subjects

C Metreweli

Publications and source records attributed to C Metreweli.

At least 19 recordsLinked to original sources

PubMed2002

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.

Adolescent↗

PubMed2002

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.

Adult↗

PubMed2002

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.

Adult↗

PubMed2001

Incidence of carotid stenosis in nasopharyngeal carcinoma patients after radiotherapy.

BACKGROUND: Radiation-induced carotid stenosis in patients with head and neck tumors can cause significant mortality and morbidity. This study examined the incidence of stenosis in the extracranial carotid arteries of nasopharyngeal carcinoma patients after radiotherapy. METHODS: The extracranial carotid arteries of 71 (53 male and 18 female; mean age of 53.6 years) postradiation patients with nasopharyngeal carcinoma were examined with color Doppler ultrasound. The distribution of the arterial stenosis and the degree of stenosis were documented. The results were compared with the control group, which comprised 51 newly diagnosed nasopharyngeal carcinoma patients (35 male and 16 female, mean age of 48.8 years) before radiotherapy. Incidences of risk factors for arterial stenosis such as hypertension, smoking, and hypercholesterolemia also were studied in these two groups. RESULTS: There was no significant difference in the incidence of risk factors between the two groups. Arterial stenosis was, however, more common in the postradiation group than the preradiation group (56 of 71 vs. 11 of 51). The common/internal carotid arteries (CCA/ICA) were most commonly involved (55 of 71 vs. 11 of 51; P < 0.01), followed by the external carotid artery (ECA) (32 of 71 vs. 1 of 51; P < 0.01) and vertebral artery (VA; 5 of 71 vs. 0; P = 0.069). Significant stenosis (> 50% reduction of luminal diameter) was only found in the postradiation group (21 of 71 in CCA/ICA, 11 of 71 in ECA, 4 of 71 in VA). CONCLUSIONS: This study showed that radiation could cause significant carotid stenosis. Ultrasound examinations for these patients therefore are necessary for early detection and possible intervention of this late radiation-induced complication.

Adult↗

PubMed2001

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.

Angiolymphoid Hyperplasia with Eosinophilia↗

PubMed2001

Clinically underdetected asymptomatic and symptomatic carotid stenosis as a late complication of radiotherapy in Chinese nasopharyngeal carcinoma patients.

BACKGROUND: Carotid artery stenosis is a late complication of radiotherapy to the neck region. This complication has, however, a significant impact with increased risk of stroke causing mortality and morbidity. Clinicians' awareness of this complication and early detection is therefore important. METHODS: Eighty patients with nasopharyngeal carcinoma (NPC) who had received radiotherapy were recruited for color Doppler ultrasonography of the carotid arteries. fifty-eight patients with newly diagnosed NPC who had never received any radiotherapy were recruited as controls. All patients with significant carotid stenosis were referred to the neurology clinic for further assessment. RESULTS: Twenty-four patients were found to have more than 50% diameter reduction in the extracranial carotid artery. Clinical assessment by a neurologist showed 9 of 24 patients had a history of transient ischemic attack, amaurosis fugax, or stroke. Seven of these patients had clinically detectable neck bruit. CONCLUSIONS: Clinicians attending to patients after radiotherapy for head and neck cancers should be aware of this long-term complication of radiotherapy. A detailed clinical history and incorporation of auscultation of carotid arteries in routine follow-up of postradiotherapy patients are recommended.

Adult↗

PubMed2001

Sonography of the normal scapholunate ligament and scapholunate joint space.

PURPOSE: The aims of this study were to assess the visibility of the normal scapholunate ligament on sonography and to establish the normal scapholunate joint space width in the neutral position and radial and ulnar deviation. METHODS: Two hundred normal wrists in 100 subjects (55 men and 45 women; mean age, 40 years; range, 19-83 years) were examined with high-resolution sonography (5-12-MHz linear-array transducer). The visibility and thickness of the scapholunate ligament were recorded. The width of the scapholunate joint space, or interval, was measured in the neutral position and radial and ulnar deviation. The width of the distal radius was recorded as a comparative standard for the patients' body habitus. RESULTS: The dorsal scapholunate ligament was completely (100%) visible in 95 wrists (48%), partially (> or = 50%) visible in 60 (30%), barely (< 50%) visible in 15 (8%), and not visible in 30 (15%). The volar scapholunate ligament was completely visible in 13 wrists (7%), partially visible in 17 (9%), barely visible in 15 (8%), and not visible in 151 (76%). The proximal component of the ligament was not visible in any subject. Measurement of the scapholunate interval was limited by the lack of identifiable anatomic marks for reference. The mean width of the dorsal scapholunate interval was 4.2 mm (range, 2.3-6.3 mm) in the neutral position. The interval did not differ more than 2.5 mm between the left and right wrists. No predictable change in width on ulnar or radial deviation was evident. The mean scapholunate intervals and mean distal radial width were significantly wider in men than in women and on the right side than on the left side. CONCLUSIONS: The dorsal scapholunate ligament is completely or partially visible in 78% of normal wrists. Its detection following injury may help to exclude the possibility of scapholunate dissociation. There is a quite wide variation in scapholunate interval widths on sonography and an unpredictable response with stress testing. The absence of a visible scapholunate ligament on sonography does not indicate injury.

Adult↗

PubMed2001

Video cystometry in young infants with renal dilation or a history of urinary tract infection.

Cystometry is increasingly being used in infants to diagnose bladder dysfunction. However, infantile urodynamic patterns have not been fully established. In this study we investigated the urodynamic patterns in young infants with renal dilation or a history of urinary tract infection, but with no apparent lower urinary tract symptoms. We use video cystometry with simultaneous perineal EMG recording. Thirty-five infants (27 male and 8 female) with congenital renal dilatation or a history of urinary tract infection at age 2 days to 24 months old were involved. We found that detrusor instability occurred in 8.6% of these subjects. Bladder capacity increased with age but less than would nomally be expected. An intermittent voiding pattern was observed in 57% (20/35) of subjects and was characterized by a single or recurring increase in sphincter activity with a simultaneous rise in the voiding detrusor pressure curve. The maximum voiding detrusor pressure with pelvic floor overactivity was significantly higher than that with no pelvic floor overactivity (105+/-44 cmH2O vs 69+/-22 cmH2O, P < 0.001). The median post-voiding residual volume was 2 (range 0 to 65) ml. We conclud that in infants with no apparent lower urinary tract symptoms, bladder instability is uncommon, and the capacity is lower than the normally expected range; an intermittent voiding pattern is common and the residual urine volume showed great variation. This probably represents an immature detrusor-sphincter function.

Dilatation, Pathologic↗

PubMed2001

Alveolar soft-part sarcoma: a rare soft-tissue malignancy with distinctive clinical and radiological features.

Alveolar soft-part sarcoma (ASPS) is a rare tumour. Certain distinctive clinical and radiological features suggest the correct diagnosis. There is moderate predilection for young women. ASPS almost always arises in skeletal muscle and occurs most frequently in the lower limbs. There is often a long clinical history and a large mass at presentation. Two young females with ASPS presented with very vascular tumours in the thigh, with prominent intra- and extra-tumoural blood vessels. The imaging findings and the existing literature are reviewed.

Adolescent↗

PubMed2001

Pre-operative grading of intracranial glioma.

AIM: To compare the accuracy of MR-determined cerebral blood volume (CBV) maps with SPECT imaging with thallium-201 in pre-operative grading of intracranial glioma. MATERIAL AND METHODS: Nineteen patients (7 female and 12 male, mean age 46.8 years) with intracranial gliomas were examined with MR perfusion imaging pre-operatively. Sixteen of these patients were also examined with SPECT imaging with thallium-201. The tumour to contralateral white matter NI (negative integral) and tracer uptake ratios were evaluated. The ratios in high-grade and low-grade tumours were compared. RESULTS: The maximum CBV ratios of grades I and II gliomas (2.958+/-2.217) were significantly lower than the maximum CBV ratio of grades III and IV (9.484+/-4.520), p<0.001. There was no statistical difference when CBV ratios of grades I and II (p=0.381), grades II and III (p=0.229) and grades III and IV (p=0.476) gliomas were compared. Thallium SPECT imaging showed no difference in tumour uptake ratio between low-grade and high-grade gliomas (p=0.299). CONCLUSION: MR-determined NI was useful for pre-operative grading of intracranial gliomas but SPECT thallium-201 imaging was not.

Adolescent↗

PubMed2001

Incidence of deep vein thrombosis after colorectal surgery in a Chinese population.

INTRODUCTION: Contemporary studies indicate that the incidence of deep vein thrombosis (DVT) is increasing in the Asian population. The present study aims to evaluate the incidence of postoperative DVT in Chinese patients undergoing surgery for colorectal malignancies. METHODS: Fifty-one consecutive patients with carcinoma of the rectum or sigmoid colon scheduled for resection were included in the study. None of the study subjects were given any form of DVT prophylaxis. Serial duplex ultrasound of both lower limbs were examined in the preoperative and postoperative periods. RESULTS: Three patients were excluded from the study because of the presence of DVT noted preoperatively. A total of 20/48 (41.7%) patients developed asymptomatic calf vein thrombosis. One out of 20 patients required anticoagulation because of thrombus propagation. None of the subjects showed signs or symptoms of DVT or pulmonary embolism. A total of 7/20 thrombi resolved completely at 4 weeks after operation. Only old age and smoking were identified as being associated with a higher incidence of DVT. Disseminated disease, type of operation, duration of operation and postoperative complications did not appear to be risk factors for DVT. CONCLUSION: A high incidence of asymptomatic calf vein thrombosis occurred after colorectal surgery for malignancies in Chinese. The majority did not progress even without anticoagulation.

Age Factors↗

PubMed2001

Distribution of intranodal vessels in differentiating benign from metastatic neck nodes.

AIM: Recent studies report high accuracy of power Doppler sonography in the differentiation of benign from malignant cervical lymphadenopathy. This study was undertaken to identify which of the parameters used in Doppler sonography of cervical lymph nodes is accurate and readily applicable in routine clinical practice. MATERIALS AND METHODS: We reviewed the power Doppler ultrasound examinations of 50 patients with cytologically proven metastatic nodes from nasopharyngeal carcinoma and 50 patients with proven reactive lymphadenopathy. All the examinations had been performed by an experienced sonologist, and intranodal vascular distribution and resistance were evaluated during real-time ultrasound. Twenty metastatic nodes and 40 reactive nodes were less than 10 mm in maximum transverse diameter. The vascular patterns of lymph nodes were classified into three categories: (1) hilar; (2) capsular; (3) hilar and capsular. The resistive index (RI) and pulsatility index (PI) were measured by spectral Doppler. RESULTS: Although metastatic nodes (RI, 0.81 +/- 0.11; PI, 1.89 +/- 0.89) tended to have higher intranodal vascular resistance than reactive nodes (RI, 0.65 +/- 0.08; PI, 1.07 +/- 0.26), there was considerable overlap of the resistance parameters between benign and malignant nodes. Most of the metastatic nodes showed the presence of capsular vascularity (capsular, 16%; capsular and hilar, 78%), whereas the majority of the reactive nodes showed hilar vascularity (98%), and the difference was significant. CONCLUSION: The distribution of intranodal vascularity appears to be more useful than RI or PI in differentiating benign from malignant cervical lymphadenopathy. It is also easier to evaluate the distribution and the results are therefore readily applicable in routine clinical practice.

Adult↗

PubMed2001

Does anybody know how we should measure Doppler parameters in lymph nodes?

AIM: To show how currently described techniques confuse interpretation of Doppler indices in lymph node characterization. MATERIALS AND METHODS: The Doppler indices [resistivity index (RI) and pulsatility index (PI)] were obtained in 35 malignant lymph nodes by colour duplex sonography. Each node was sampled at eight different sites. Data were analysed using our own method, and methods employed in six previous studies. RESULTS: Restistivity index values varied between 0.69 and 0.88 and PI values ranged from 1.28 to 2.34. All but two methods produced different resistance indices (P < 0.05). CONCLUSION: Conflicting results are obtained analysing the same data using different methods. Standardized techniques should be agreed and employed in future studies.

Blood Flow Velocity↗

PubMed2001

Power Doppler sonography of metastatic nodes from papillary carcinoma of the thyroid.

AIMS: Metastatic nodes on power Doppler sonography tend to demonstrate high intranodal resistance and abnormal distribution of vascularity within a node. However, in our experience metastatic nodes from papillary carcinoma of the thyroid frequently demonstrate low intranodal resistance and some do not demonstrate the presence of any abnormal vascularity within. We were therefore interested to document these features. MATERIALS AND METHODS: The grey scale and power Doppler sonograms of 21 metastatic nodes from papillary carcinoma of the thyroid were evaluated. The intranodal distribution of vessels and the intranodal vascular resistance of vessels was assessed and compared with the reported features of metastatic nodes from other head and neck primaries. RESULTS: A majority (17/20, 85%) of metastatic nodes from papillary carcinoma of the thyroid had a maximum resistance index (RI) and pulsatility index (PI) < 0.8 and 1.6, respectively. A majority of the nodes (16/21, 76%) demonstrated abnormal capsular vascularity within the nodes. CONCLUSION: Metastatic nodes from papillary carcinoma on power Doppler sonography frequently have low RI and PI and 24% demonstrate just prominent hilar vascularity similar to reactive nodes.

Adolescent↗

PubMed2001

'Pseudocystic' appearance of non-Hodgkin's lymphomatous nodes: an infrequent finding with high-resolution transducers.

AIMS: A pseudo-cystic appearance and posterior enhancement are previously reported to be diagnostic sonographic features of lymph node involvement in non-Hodgkin's lymphoma. This study was undertaken to determine whether these ultrasonic features remain with the use of high-resolution transducers. MATERIAL AND METHODS: A review of ultrasound examinations in 32 patients with proven lymphomatous cervical lymphadenopathy (27 non-Hodgkin's lymphoma, five Hodgkin's disease) was performed. A total of 95 lymph nodes were assessed for size, shape, posterior enhancement and internal architecture. All examinations were performed with the same high-resolution transducer and by the same sonologist. RESULTS: Lymphomatous nodes (irrespective of type) are frequently heterogeneous (68-86%), have a micronodular pattern (63-69%) and less commonly demonstrate posterior enhancement (9-26%). CONCLUSION: Using a high-resolution ultrasonic transducer, cervical nodes involved with lymphoma (irrespective of type) commonly demonstrate a heterogeneous micronodular pattern. The pseudocystic appearance of nodes with posterior enhancement in non-Hodgkin's nodes is seen infrequently.

Adolescent↗

PubMed2001

Vascularity and grey-scale sonographic features of normal cervical lymph nodes: variations with nodal size.

AIM: This study was undertaken to investigate variations in the vascularity and grey-scale sonographic features of cervical lymph nodes with their size. MATERIALS AND METHODS: High resolution grey-scale sonography and power Doppler sonography were performed in 1133 cervical nodes in 109 volunteers who had a sonographic examination of the neck. Standardized parameters were used in power Doppler sonography. RESULTS: About 90% of lymph nodes with a maximum transverse diameter greater than 5 mm showed vascularity and an echogenic hilus. Smaller nodes were less likely to show vascularity and an echogenic hilus. As the size of the lymph nodes increased, the intranodal blood flow velocity increased significantly (P < 0.05), whereas there was no significant variation in the vascular resistance(P> 0.05). CONCLUSIONS: The findings provide a baseline for grey-scale and power Doppler sonography of normal cervical lymph nodes. Sonologists will find varying vascularity and grey-scale appearances when encountering nodes of different sizes.Ying, M.et al. (2001). Clinical Radiology, 56, 416-419.

Adult↗

PubMed2001

Power Doppler sonography of cervical lymphadenopathy.

AIMS: The supraclavicular region is a common site for tuberculous and metastatic nodes from infraclavicular carcinomas. Grey scale sonographic features differentiating the two have been previously described. However, as power Doppler sonography is now frequently used in the assessment of neck nodes, power Doppler features that may help to differentiate the two are discussed. MATERIALS AND METHODS: In 78 patients, power Doppler sonograms of nodes involved by metastases from infraclavicular carcinomas (n = 24) and tuberculosis (n = 54) were evaluated. The intranodal distribution of vessels and the intranodal vascular resistance of vessels was assessed and compared. In addition, the power Doppler features of metastatic nodes from infraclavicular carcinomas were compared with metastatic nodes from a head and neck primary (n = 38) such as nasopharyngeal carcinoma (NPC). RESULTS: Tuberculous nodes frequently demonstrated displaced hilar vascularity or avascularity and the intranodal vascular resistance was low. Metastatic nodes from infraclavicular primaries demonstrated capsular or mixed vascularity and their intranodal resistance was significantly (P < 0.05) higher. In general, metastatic nodes from infraclavicular primaries had a higher intranodal vascular resistance compared to metastatic nodes from NPC, but this was not statistically significant. CONCLUSION: In the supraclavicular region, the presence of displaced low resistance hilar vascularity or avascularity in nodes is suggestive of tuberculous nodes. Metastatic nodes from infraclavicular primaries have a capsular or mixed vascularity with high resistance.

Adult↗

PubMed2001

Dentascan in oral imaging.

In the past, dental disease and lesions involving the jaw were either evaluated by plain radiography or tomography. The advent of spiral computed tomography (CT) and DentaScan is changing the imaging trend. It is now not only used for pre-implant assessment but also in the diagnosis of lesions affecting the jaw. This pictorial review discusses the role of DentaScan in the various abnormalities that may affect the mandible and maxilla.

Ameloblastoma↗