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Biomedical subjects

C Metreweli

Publications and source records attributed to C Metreweli.

At least 73 records · Page 4Linked to original sources
PubMed2000

Patients with breast cancer: differences in color Doppler flow and gray-scale US features of benign and malignant axillary lymph nodes.

PURPOSE: To document differences in color Doppler flow and gray-scale ultrasonographic (US) features between benign and malignant axillary lymph nodes in women with primary breast cancer. MATERIALS AND METHODS: The longitudinal-transverse axis ratio and hilar status on color Doppler flow and gray-scale US images were prospectively studied for each of 145 axillary nodes in 135 women (74 palpable nodes in 69 women, 71 nonpalpable nodes in 66 women) with primary breast cancer. Intranodal flow distribution was described as peripheral, central, or central perhilar. Resistive and pulsatility indexes and peak systolic velocity were documented. For comparison of benign and malignant features, nodes were divided into three groups: palpable and nonpalpable, palpable, and nonpalpable. RESULTS: Color flow was demonstrated equally well in benign and malignant axillary lymph nodes for all three groups. For all nodes, peripheral flow was significantly higher in malignant (118 of 153 nodes [77%]) than benign (45 of 160 nodes [28%]) nodes (P <.001); central flow and central perhilar flow were significantly greater (P <.002 and <.001, respectively) in benign than malignant nodes. Similar differences were not observed in nonpalpable nodes. The mean longitudinal-transverse axis ratio (+/- SD) was significantly lower in malignant (1.8 +/- 0.6) than benign (2.6 +/- 0.8) nodes. Logistic regression analysis showed peripheral, central, and central perhilar flow and the mean longitudinal-transverse axis ratio to be significant independent predictors of malignancy. CONCLUSION: Color Doppler flow and gray-scale US features applicable to the identification of disease in palpable axillary nodes in patients with breast cancer are not applicable to nonpalpable nodes.

Adult↗
PubMed2000

Preferred technique for blood flow volume measurement in cerebrovascular disease.

BACKGROUND AND PURPOSE: A noninvasive reliable technique that can reveal cerebral blood flow volume could be a valuable tool in screening programs for stroke prevention. In diagnostic ultrasonography, spectral Doppler imaging (SDI) is popular among sonologists and vascular technologists to estimate blood flow volume despite its documented inaccuracy and the availability of the more accurate technique of color velocity imaging (CVI). The aim of the present study was to demonstrate the discrepancy of blood flow volume estimation with CVI and SDI with use of an "internal" standard. METHODS: The common, internal, and external carotid arteries of 50 healthy subjects (22 men, 28 women, age range 19 to 54 years) were examined with CVI and SDI. The total blood flow volume of the internal and external carotid arteries was then compared with the ipsilateral common carotid artery flow. An accurate technique would demonstrate no difference. The difference (expressed as a percent inconsistency) was therefore a measure of the accuracy of the method. RESULTS: The mean+/-SD inconsistency was found to be 10.6+/-8.3% for CVI and 27.9+/-14.3% for SDI. The difference in inconsistency between CVI and SDI in measurement of carotid blood flow volume was statistically significant (P<0.01). CONCLUSIONS: CVI is more accurate than SDI in the determination of blood flow volume in the carotid arteries. For noninvasive clinical estimation of cerebrovascular blood flow volume, CVI quantification should be the preferred technique.

Adult↗
PubMed2000

CT and DSA appearances of a ruptured congenital arteriovenous malformation of the posterior mediastinal aorta.

A case of symptomatic congenital arteriovenous malformation detected in an adult patient is presented. The diagnosis was not suspected clinically but was demonstrated by CT and digital subtraction angiography. Although very rare, a congenital arteriovenous malformation of the posterior mediastinal aorta could present as a catastrophic event if it ruptures. Serpiginous vascular channels in the retro-oesophageal posterior mediastinum on CT and angiography should raise the possibility of an arteriovenous malformation.

Angiography, Digital Subtraction↗
PubMed2000

Ultrasonographic imaging of the testis and epididymis of the bottlenose dolphin, Tursiops truncatus aduncas.

Eight male bottlenose dolphins, Tursiops truncatus aduncas, underwent examination of the reproductive organs to investigate the use of real-time B-mode ultrasonography in assessment of reproductive status and to establish normal ultrasonographic appearances. Ultrasonography allowed repeatable examinations which were well tolerated by all animals. Ultrasonography was used to examine the testes, epididymides, vasa deferentia, penis, bulbourethral and bulbocavernosal muscles; the prostate was not convincingly distinguished from surrounding muscles. Testicular echopatterns and size differed among individuals. Three distinct testicular echopatterns were discerned and could be used to differentiate males of different reproductive status. Ultrasonographic appearance of the testes provides useful data in assessing the reproductive status of male dolphins.

Animals↗
PubMed2000

MR imaging of nasal T-cell/natural killer cell lymphoma.

OBJECTIVE: Nasal T-cell/natural killer cell lymphoma is a distinct clinicopathologic entity derived from natural killer cells. The purpose of the study was to describe the MR features of this rare nasal cavity tumor and correlate MR findings with stage of disease. CONCLUSION: Nasal T-cell/natural killer cell lymphoma frequently exhibits diffuse invasion of the nasal cavity with necrosis, midline destruction, and extension into the nasopharynx. These features may be seen in both early- and late-stage disease.

Adult↗
PubMed2000

Comparison of dynamic helical CT and dynamic MR imaging in the evaluation of pelvic lymph nodes in cervical carcinoma.

OBJECTIVE: This study compares dynamic helical CT with dynamic MR imaging in the evaluation of pelvic lymph nodes in cervical carcinoma. SUBJECTS AND METHODS: Women with biopsy-proven cervical carcinoma prospectively underwent dynamic helical CT and MR imaging before surgery. A metastatic node on CT and MR imaging was defined as a rounded soft-tissue structure greater than 10 mm in maximal axial diameter or a node with central necrosis. Imaging results were compared with pathology, and receiver operating characteristic curves for size and shape were plotted on a hemipelvis basis. Nodal density and signal intensity on CT and MR images, respectively, were reviewed for differences between benign and malignant disease. RESULTS: A total of 949 lymph nodes were found at pathology in 76 hemipelves in 43 women, of which 69 lymph nodes (7%) in 17 hemipelves (22%) were metastatic. Sensitivity, specificity, positive and negative predictive values, and accuracy of helical CT and MR imaging in the diagnosis of lymph node metastasis on a hemipelvis basis was 64.7%, 96.6%, 84.6%, 90.5%, and 89.5% and 70.6%, 89.8%, 66. 7%, 91.4%, and 85.5%, respectively. Receiver operating characteristic curves for helical CT and MR imaging gave cutoff values of 9 and 12 mm in maximal axial diameter, respectively, in the prediction of metastasis. Central necrosis had a positive predictive value of 100% in the diagnosis of metastasis. Signal intensity on MR imaging and density-enhancement pattern on CT in patients with metastatic nodes did not differ from those in patients with negative nodes. CONCLUSION: Helical CT and MR imaging show similar accuracy in the evaluation of pelvic lymph nodes in patients with cervical carcinoma. Central necrosis is useful in the diagnosis of metastasis in pelvic lymph nodes in cervical cancer.

Adult↗
PubMed2000

Power Doppler sonography of normal cervical lymph nodes.

This study was undertaken to investigate the vascular patterns and resistance of normal cervical nodes by power Doppler sonography. In 101 subjects who had a sonographic examination of the neck, 1050 lymph nodes were detected. Only central vascularity was found in normal cervical nodes. The degree of vascularity in submental and submandibular nodes was higher than that in other regional nodes. Submental nodes had a higher vascular resistance in association with a lower blood flow velocity than other regional nodes. No significant difference was found in blood flow velocities and vascular resistance between male and female subjects. The vascular resistance increased significantly with age. This study provides a baseline for vascularity within normal cervical nodes, as seen by power Doppler sonography.

Adult↗
PubMed2000

Second branchial cleft cysts: variability of sonographic appearances in adult cases.

BACKGROUND AND PURPOSE: Previous reports have suggested that second branchial cleft cysts (BCCs) appear on sonograms as well-defined, cystic masses with thin walls and posterior enhancement. Previous CT and MR imaging findings, however, have indicated heterogeneity of these masses, and, in our experience, sonography also shows a similar variable appearance. In this communication, we report the cases of 17 patients with second BCCs and document the variability of sonographic patterns. METHODS: The sonograms of 17 adults with second BCCs were reviewed. Only patients with surgical or cytologic evidence of BCCs were included in this study. The features evaluated were the location, internal echogenicity, posterior enhancement, and presence of septa and fistulous tract. RESULTS: Four patterns of second BCCs were identified: anechoic (41%), homogeneously hypoechoic with internal debris (23.5%), pseudosolid (12%), and heterogeneous (23.5%). The majority (70%) showed posterior enhancement. All were situated in their classical location, posterior to the submandibular gland, superficial to the carotid artery and internal jugular vein, and closely related to the medial and anterior margin of the sternomastoid muscle. Fourteen (82%) of the 17 BCCs had imperceptible walls, and all were well defined. For none of the patients was a fistulous tract revealed by sonography; the presence of internal septations was revealed for three patients. CONCLUSION: As previously suggested by CT and MR imaging findings, sonography reinforces that second BCCs in adults are not simple cysts but have a complex sonographic pattern ranging from a typical anechoic to a pseudosolid appearance.

Adolescent↗
PubMed2000

Intrathyroidal lymphoepithelial (branchial) cyst: sonographic features of a rare lesion.

Intrathyroidal lymphoepithelial cysts are rare, and only 15 such cases have been reported. Although sonography has been performed in some cases, the findings have not been discussed previously. Despite its rarity, the sonographic appearances of this lesion are similar to those of other commonly encountered congenital cystic lesions in the head and neck, such as thyroglossal duct cysts and second branchial cleft cysts, and this may provide a clue to its diagnosis. We describe the sonographic appearances of intrathyroidal lymphoepithelial cysts.

Biopsy, Needle↗
PubMed1999

Correlation between curve severity, somatosensory evoked potentials, and magnetic resonance imaging in adolescent idiopathic scoliosis.

STUDY DESIGN: A prospective study in patients with adolescent idiopathic scoliosis of different clinical severity using whole-spine magnetic resonance imaging and somatosensory evoked potentials. OBJECTIVES: To correlate the presence of magnetic resonance imaging structural abnormalities with somatosensory evoked potential-detected functional disorders in the hind brain and spinal cord and the Cobb's angle in patients with adolescent idiopathic scoliosis and to compare the result with those in healthy matched control subjects. SUMMARY OF BACKGROUND DATA: Many different types of neurologic dysfunction have been reported in scoliosis. With the advent of magnetic resonance imaging, there are increased reports on the association of idiopathic scoliosis and syringomyelia, Chiari I malformation, or tonsillar ectopia. The actual link between structural and functional disorder in idiopathic scoliosis is, however, unclear. METHODS: Posterior tibial nerve evoked potentials and whole-spine magnetic resonance imaging were performed in 36 healthy control subjects, 135 patients with adolescent idiopathic scoliosis with Cobb's angle less than 45 degrees, and 29 patients with Cobb's angle more than 45 degrees. RESULTS: Tonsillar ectopia or syringomyelia, detected by magnetic resonance imaging, or functional disturbance in the somatosensory pathway, detected by somatosensory evoked potentials, was found to be significantly more frequent in the group of patients with severe scoliosis curvature, with an incidence of 31% and 27.6%, respectively. Incidence of tonsillar ectopia was 33.3% in patients with abnormal somatosensory evoked potentials in contrast to the much lower incidence of 2.9% in patients with normal somatosensory evoked potentials. There was a significant structural and functional link. The incidence of syringomyelia in patients with and without tonsillar ectopia was 33.3% and 0.7%, respectively. CONCLUSIONS: In patients with adolescent idiopathic scoliosis with severe curve, the significant association with tonsillar ectopia and abnormal somatosensory function points to a neural origin. Disorders in the somatosensory function may be one of the mechanisms linking tonsillar ectopia to scoliosis. Somatosensory evoked potentials and magnetic resonance imaging may have important diagnostic and predictive value and may help in the management of adolescent idiopathic scoliosis.

Adolescent↗
PubMed1999

Sonographic measurement of splenic length: correlation with measurement at autopsy.

PURPOSE: The purpose of this study was to determine the correlations between the sonographic measurement of splenic length and the actual splenic length, volume, and weight. METHODS: Before autopsy, sonographic measurements of splenic length were obtained in 30 cadavers, and these values were compared with the actual length, volume, and weight of the spleen at autopsy. RESULTS: There were clear linear correlations between maximum sonographic length and actual length (r = 0.831), volume (r = 0.817), and weight (r = 0.810). CONCLUSION: This study shows that a single, simple sonographic measurement gives a clinically useful indication of true splenic size.

Aged↗
PubMed1999

Hypoglossal nerve palsy in nasopharyngeal carcinoma.

BACKGROUND: The aim of the study was to use magnetic resonance (MR) imaging to determine the cause of hypoglossal nerve palsy and the sites of injury in patients with nasopharyngeal carcinoma before radiation therapy and during postradiation therapy follow-up. METHODS: The clinical records and MR studies of 21 patients with hypoglossal nerve palsy were retrospectively studied. These 21 patients belonged to a cohort of 387 patients with nasopharyngeal carcinoma (153 with newly diagnosed disease and 234 on postradiation follow-up) who underwent MR imaging in a 2.5-year period. RESULTS: Four patients had hypoglossal nerve palsy at initial diagnosis and all of them had extensive skull base invasion from tumor extending postero-inferiorly to the level of the foramen magnum. The nerve was invaded in the carotid sheath (3), hypoglossal nerve canal (3), and premedullary cistern (1). In 17 patients developing hypoglossal nerve palsy after radiotherapy, only two (12%) had evidence of tumor recurrence. Radiation-induced neuropathy was the probable cause in 14 patients and 1 case was judged indeterminate. MR evidence of fibrosis was demonstrable along the course the nerve in four patients (29%), involving the carotid sheath (4), hypoglossal nerve canal (2), and premedullary cistern (1). No patient had MR evidence of radiation change in the brain stem. Seven patients had a history of a boost dose of radiation to the parapharyngeal region on one or both sides, and nerve palsy occurred on the boosted side in six of them. CONCLUSION: Hypoglossal nerve palsy on presentation was caused by locally advanced nasopharyngeal tumor whereas a palsy arising after radiation therapy was more frequently caused by postradiation damage rather than cancer.

Adenocarcinoma↗
PubMed1999

MRI evaluation of multifidus muscles in adolescent idiopathic scoliosis.

BACKGROUND: The role of the multifidus muscles in the initiation and progression of curve in adolescent idiopathic scoliosis is not fully understood and controversy exists as to the side of the abnormality. OBJECTIVE: To evaluate on MRI the multifidus muscles at the apex of the major curve in adolescent idiopathic scoliosis to ascertain if the multifidus muscles on the convex or concave side are abnormal and the relationship to curve severity. MATERIALS AND METHODS: Forty-six patients with adolescent idiopathic scoliosis, separated into two groups, were studied using a 1.5-T MR scanner with the synergy spine coil, employing a modified STIR (short tau inversion recovery) axial sequence obtained at the apex of the major scoliotic curve. RESULTS: No hyperintense signal change was demonstrated in the convex side multifidus muscles in any patient. In group I, 16 of 18 patients with severe or rapidly progressive curve showed increase in signal intensity in the multifidus muscle on the concave side of the apex of the curve. In group II, of the 15 patients with mild curve (Cobb angle 10-30 degrees), 4 had increased signal intensity in the multifidus muscle on the concave side; of the 13 with more severe curve (Cobb angle greater than 30 degrees), 10 had increase in multifidus signal intensity on the concave side. CONCLUSIONS: The concave-side multifidus muscle at the apex of a scoliotic curve was morphologically abnormal. A significant association between abnormal signal change and curve severity was also established.

Adolescent↗
PubMed1999

Imaging following allograft reconstruction in children with malignant bone tumours.

PURPOSE: To determine the nature of the imaging findings following reconstructive surgery using massive allografts in children with malignant bone tumours. MATERIALS AND METHODS: A retrospective review of the imaging studies and medical charts of 25 consecutive children who received an allograft as part of the management of a malignant bone tumour. RESULTS: Uncomplicated allografts were sclerotic relative to native bone on radiographs and showed a typical 'tramline' appearance on bone scintigraphy. On MR, the medullary canal of the allograft showed low signal, similar to or greater than skeletal muscle, but less than subcutaneous fat, on 91 % of T1-weighted images. On short-tau inversion recovery images, the medullary canal was inhomogeneous and hyperintense to subcutaneous fat in 70 % and hyperintense to muscle in the remainder. Complications occurred in 68 % of patients and included allograft fractures (36 %), recurrent tumour (20 %), infection (8 %), and non-union or delayed union (8 %). The radiographic findings alone permitted accurate diagnosis of most serious complications. Infection and rejection were difficult to distinguish with any technique. All complications were suspected on clinical and/or radiological grounds before being shown by MR or scintigraphy. CONCLUSIONS: Allografts, whether normal or complicated, have characteristic imaging findings, except that infection and bone resorption related to rejection and revascularisation are difficult to distinguish. Routine MR and bone scintigraphy appear to contribute little to the management of these patients.

Adolescent↗
PubMed1999

Potential utility of MRI in the evaluation of children at risk of renal scarring.

BACKGROUND: Gadolinium-enhanced MRI has recently been employed in the diagnosis of acute pyelonephritis. Its potential utility in the diagnosis of renal scars in children is unknown. Objective. To evaluate the potential utility of MRI using fat-saturated T1-weighted (T1-W) and post-gadolinium, short-tau inversion-recovery (STIR) sequences in detecting renal scarring by comparison with technetium dimercaptosuccinic acid ((99 m)Tc-DMSA) renal scintigraphy in children at risk of renal scarring. MATERIALS AND METHODS: A group of 24 children with spina bifida and neurogenic bladder or anorectal anomaly was studied. No patient had a history of acute pyelonephritis. Documented urinary tract infection (UTI) was present in 10 children (42 %). The remaining 14 (58 %) children had a history of asymptomatic bacteriuria. None had clinical signs or symptoms of acute UTI at the time of the study. (99 m)Tc-DMSA and MRI were performed to detect renal scarring. (99 m)Tc-DMSA scans were supplemented with pinhole imaging. MRI of the kidneys employed a fat-saturated T1-W sequence and a post-gadolinium STIR sequence employing a short echo time. RESULTS: Of the kidneys studied, 33 % (n = 16) had evidence of a renal parenchymal defect suggestive of scarring on (99 m)Tc-DMSA. The concordance in the detection of a scarred kidney by post-gadolinium STIR sequence and (99 m)Tc-DMSA is 94 %; that by fat-saturated T1-W sequence and (99 m)Tc-DMSA is 82 %; that by both sequences (positive result on either sequence) and (99 m)Tc-DMSA is 100 %. Using (99 m)Tc-DMSA as the gold standard, MRI had a sensitivity of 100 % and a specificity of 78 % in the diagnosis of a scarred kidney. The concordance in the detection of a scarred zone by post-gadolinium STIR sequence and (99 m)Tc-DMSA is 68 %; that by fat-saturated T1-W sequence and DMSA is 44 %; that by both sequences (positive result on either sequence) and (99 m)Tc-DMSA is 84 %. MRI had a sensitivity of 84 % and a specificity of 86 % in the diagnosis of a scarred zone, using (99 m)Tc-DMSA as the gold standard. CONCLUSION: The detection rate for renal scarring on MRI using the fat-saturated T1-W and post-gadolinium STIR sequences is comparable to planar (99 m)Tc-DMSA. MRI is of potential utility in the evaluation of children at risk of renal scarring.

Anal Canal↗
PubMed1999

Deep vein thrombosis in elderly Hong Kong Chinese with hip fractures detected with compression ultrasound and Doppler imaging: incidence and effect of low molecular weight heparin.

Seventy-eight patients of average age 78 years suffering from an unilateral non-pathological hip fracture underwent compression ultrasound and pulsed and colour Doppler examination of both legs. Twenty-three patients were randomly placed on low molecular weight heparin (LMWH). Twenty-nine (37%) suffered deep venous thrombosis (DVT). There was no statistically significant difference in the incidence of DVT between the control and LMWH groups, and the incidence of DVT in elderly Chinese patients after hip replacement for a hip fracture is similar to that in other studies in Caucasians. There were, however, some differences, namely the contiguous nature of the thrombi rather than focal segmental clots, and the absence of propagation or tail formation. Although the numbers are small, this could possibly represent a population difference. There was a significantly increased occurrence of DVTs on the operated side in both groups. Serial ultrasound examination supports evidence that DVTs occur in the 1st week postoperatively, but there were also a number of patients who developed DVTs in the 2nd week. There was no statistically significant difference in overall incidence of DVT between patients on prophylactic heparin and the control group. Patients on prophylactic heparin had no thigh DVTs in comparison to the control group. LMWH may thus be effective in preventing thigh DVTs and pulmonary emboli.

Aged↗
PubMed1999

Palatal lymphoepitheliomas and a review of head and neck lymphoepitheliomas.

AIM: Lymphoepithelioma is principally a tumour of the nasopharynx with only sporadic cases arising elsewhere in the head and neck. We describe the clinical and imaging features of a group of rare lymphoepitheliomas related to the palate. PATIENTS AND METHODS: Four patients with lymphoepithelioma of the palate are described. In each case we retrospectively reviewed the clinical records, laboratory results, and imaging which consisted of computed tomography (CT) and ultrasound in all four cases and magnetic resonance imaging (MRI) in two patients. RESULTS: All four patients were ethnic Chinese (non-smokers, non-drinkers). All cases were Epstein-Barr virus (EBV) related. Tumour was related to the palate in two cases and extended into the nasal cavity in one patient. The fourth patient had a tumour in the floor of the nasal cavity with invasion of the palate on biopsy but not imaging. Cervical lymphadenopathy was seen in two cases, and the nasopharynx was normal in all the four patients. CONCLUSION: Lymphoepitheliomas occur in the region of the palate, where they are also EBV related in southern Chinese. Compared with the keratinizing squamous cell carcinomas, patients with lymphoepitheliomas have a better prognosis and these tumours are not tobacco or alcohol related. They should not be misdiagnosed as metastatic nasopharyngeal carcinoma (NPC), particularly since the nasopharynx is invariably normal on imaging and adequate nasopharyngeal biopsy is negative for malignancy.

Aged↗