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1.
Magn Reson Med ; 92(5): 2237-2245, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38968006

RESUMO

The "5 gauss line" is a phrase that is likely to be familiar to everyone working with MRI, but what is its significance, how was it defined, and what changes are currently in progress? This review explores the history of 5 gauss (0.5 mT) as a threshold for protecting against inadvertently putting cardiac pacemakers, implantable cardioverter defibrillators, and other active implantable medical devices into a "magnet mode." Additionally, it describes the background to the recent change of this threshold to 9 gauss (0.9 mT) in the International Standard IEC 60601-2-33 edition 4.0 that defines basic safety requirements for MRI. Practical implications of this change and some ongoing and emerging issues are also discussed.


Assuntos
Imageamento por Ressonância Magnética , Humanos , Marca-Passo Artificial , Desfibriladores Implantáveis , Próteses e Implantes , Segurança de Equipamentos , Imãs , Campos Eletromagnéticos
2.
MAGMA ; 34(4): 513-521, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33355719

RESUMO

OBJECTIVE: To compare integrated slice-specific dynamic shim (iShim) with distortion correction post-processing to conventional 3D volume shim for the reduction of artefacts and signal loss in 1.5 T whole-body diffusion-weighted imaging (WB-DWI). METHODS: Ten volunteers underwent WB-DWI using conventional 3D volume shim and iShim. Forty-eight consecutive patients underwent WB-DWI with either volume shim (n = 24) or iShim (n = 24) only. For all subjects, displacement of the spinal cord at imaging station interfaces was measured on composed b = 900 s/mm2 images. The signal intensity ratios, computed as the average signal intensity in a region of high susceptibility gradient (sternum) divided by the average signal intensity in a region of low susceptibility gradient (vertebral body), were compared in volunteers. For patients, image quality was graded from 1 to 5 (1 = Poor, 5 = Excellent). Signal intensity discontinuity scores were recorded from 1 to 4 (1 = 2 + steps, 4 = 0 steps). A p value of < 0.05 was considered significant. RESULTS: Spinal cord displacement artefacts were lower with iShim (p < 0.05) at the thoracic junction in volunteers and at the cervical and thoracic junctions in patients (p < 0.05). The sternum/vertebra signal intensity ratio in healthy volunteers was higher with iShim compared with the volume shim sequence (p < 0.05). There were no significant differences between the volume shim and iShim patient groups in terms of image quality and signal intensity discontinuity scores. CONCLUSION: iShim reduced the degree of spinal cord displacement artefact between imaging stations and susceptibility-gradient-induced signal loss.


Assuntos
Artefatos , Imagem de Difusão por Ressonância Magnética , Imagem Ecoplanar , Humanos , Medula Espinal/diagnóstico por imagem , Coluna Vertebral
3.
Diabetes Obes Metab ; 22(10): 1808-1817, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32488928

RESUMO

AIM: To investigate relationships between insulin clearance, insulin secretion, hepatic fat accumulation and insulin sensitivity in black African (BA) and white European (WE) men. METHODS: Twenty-three BA and twenty-three WE men with normal glucose tolerance, matched for age and body mass index, underwent a hyperglycaemic clamp to measure insulin secretion and clearance, hyperinsulinaemic-euglycaemic clamp with stable glucose isotope infusion to measure whole-body and hepatic-specific insulin sensitivity, and magnetic resonance imaging to quantify intrahepatic lipid (IHL). RESULTS: BA men had higher glucose-stimulated peripheral insulin levels (48.1 [35.5, 65.2] × 103 vs. 29.9 [23.3, 38.4] × 103 pmol L-1 × min, P = .017) and lower endogeneous insulin clearance (771.6 [227.8] vs. 1381 [534.3] mL m-2 body surface area min -1 , P < .001) compared with WE men. There were no ethnic differences in beta-cell insulin secretion or beta-cell responsivity to glucose, even after adjustment for prevailing insulin sensitivity. In WE men, endogenous insulin clearance was correlated with whole-body insulin sensitivity (r = 0.691, P = .001) and inversely correlated with IHL (r = -0.674, P = .001). These associations were not found in BA men. CONCLUSIONS: While normally glucose-tolerant BA men have similar insulin secretory responses to their WE counterparts, they have markedly lower insulin clearance, which does not appear to be explained by either insulin resistance or hepatic fat accumulation. Low insulin clearance may be the primary mechanism of hyperinsulinaemia in populations of African origin.


Assuntos
Diabetes Mellitus , Hiperinsulinismo , Resistência à Insulina , Negro ou Afro-Americano , População Negra , Técnica Clamp de Glucose , Humanos , Insulina , Masculino
5.
Radiology ; 272(1): 100-12, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24654970

RESUMO

PURPOSE: To evaluate whether changes in magnetic resonance (MR) imaging heterogeneity may aid assessment for pathologic complete response (pCR) to neoadjuvant chemotherapy (NACT) in primary breast cancer and to compare pCR with standard Response Evaluation Criteria in Solid Tumors response. MATERIALS AND METHODS: Institutional review board approval, with waiver of informed consent, was obtained for this retrospective analysis of 36 consecutive female patients, with unilateral unifocal primary breast cancer larger than 2 cm in diameter who were receiving sequential anthracycline-taxane NACT between October 2008 and October 2012. T2- and T1-weighted dynamic contrast material-enhanced MR imaging was performed before, at midtreatment (after three cycles), and after NACT. Changes in tumor entropy (irregularity) and uniformity (gray-level distribution) were determined before and after MR image filtration (for different-sized features). Entropy and uniformity for pathologic complete responders and nonresponders were compared by using the Mann-Whitney U test and receiver operating characteristic analysis. RESULTS: With NACT, there was an increase in uniformity and a decrease in entropy on T2-weighted and contrast-enhanced subtracted T1-weighted MR images for all filters (uniformity: 23.45% and 22.62%; entropy: -19.15% and -19.26%, respectively). There were eight complete pathologic responders. An area under the curve of 0.84 for T2-weighted MR imaging entropy and uniformity (P = .004 and .003) and 0.66 for size (P = .183) for pCR was found, giving a sensitivity and specificity of 87.5% and 82.1% for entropy and 87.5% and 78.6% for uniformity compared with 50% and 82.1%, respectively, for tumor size change for association with pCR. CONCLUSION: Tumors become more homogeneous with treatment. An increase in T2-weighted MR imaging uniformity and a decrease in T2-weighted MR imaging entropy following NACT may provide an earlier indication of pCR than tumor size change.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Imageamento por Ressonância Magnética/métodos , Terapia Neoadjuvante , Adulto , Idoso , Antraciclinas/administração & dosagem , Anticorpos Monoclonais Humanizados/administração & dosagem , Meios de Contraste , Docetaxel , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade , Software , Técnica de Subtração , Taxoides/administração & dosagem , Trastuzumab , Resultado do Tratamento
6.
Invest New Drugs ; 31(4): 900-9, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23143778

RESUMO

BACKGROUND: Several cancer therapies can prolong cardiac repolarization. This study assessed the potential of eribulin to affect cardiac repolarization in patients with advanced solid tumors. METHODS: In this Phase I, open-label, single-arm study, patients received eribulin mesylate (1.4 mg/m(2); Days 1 and 8 of a 21-day cycle). The primary objective was to assess the effect of eribulin on the QTcF pre- and post-infusion; QTcF and QTcNi were compared for ability to remove heart-rate dependence of the QT interval. Relationship between concentration of eribulin and ΔQTc was explored using linear mixed-effects analysis. Secondary objectives explored pharmacokinetics, safety, and tolerability. RESULTS: Twenty-six patients were enrolled. QTcNi was more effective than QTcF in correcting for heart-rate dependency of the QT interval. On Day 1, mean ΔQTcNi were ~0 at all timepoints. An apparent time-dependent increase in ΔQTc was observed: on Day 8, changes from baseline were larger and more variable, without clear relation to plasma levels of eribulin. Day 8 predose ΔQTcNi was 5 ms, post-infusion mean values ranged from 2 to 9 ms (largest mean ΔQTcNi at 6 h). No new or unexpected toxicities were reported. CONCLUSION: Eribulin demonstrated an acceptable safety profile and a minor prolongation of QTc not expected to be of clinical concern in oncology patients.


Assuntos
Eletrocardiografia , Furanos/uso terapêutico , Cetonas/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológico , Adulto , Idoso , Algoritmos , Intervalos de Confiança , Demografia , Feminino , Furanos/efeitos adversos , Furanos/sangue , Furanos/farmacocinética , Frequência Cardíaca , Humanos , Cetonas/efeitos adversos , Cetonas/sangue , Cetonas/farmacocinética , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias/sangue , Neoplasias/fisiopatologia , Ultrassonografia
7.
Br J Clin Pharmacol ; 75(2): 507-15, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22803519

RESUMO

AIM: Eribulin mesylate is a non-taxane microtubule dynamics inhibitor that was recently approved for treatment of metastatic breast cancer. The aim of this study was to determine the effect of rifampicin, a CYP3A4 inducer, on the plasma pharmacokinetics of eribulin in patients with solid tumours. METHODS: An open-label, non-randomized phase I study was carried out. Patients received intravenous 1.4 mg m(-2) eribulin mesylate on days 1 and 15 and oral rifampicin 600 mg on days 9 to 20 of a 28 day cycle. Pharmacokinetic sampling for determination of eribulin plasma concentrations was performed up to 144 h following administration. AUC(0,∞) and C(max) for eribulin exposure without or with co-administration of rifampicin were subjected to an analysis of variance (anova) and corresponding 90% confidence intervals (CI) were calculated. Subsequently, patients were allowed to continue eribulin mesylate treatment with 1.4 mg m(-2) eribulin mesylate on days 1 and 8 of a 21 day cycle. Also the adverse event profile and anti-tumour activity were assessed. RESULTS: Fourteen patients were included and 11 patients were evaluable for pharmacokinetic analysis. Co-administration of rifampicin had no effect on single dose exposure to eribulin (geometric least square means ratio: AUC(0,∞) = 1.10, 90% CI 0.91, 1.34 and C(max) = 0.97, 90% 0.81, 1.17). The most common treatment-related grade ≥3 adverse events were grade 3 neutropenia (4/14, 29%), leucopenia and fatigue (both 3/14, 21%). CONCLUSIONS: These results indicate that eribulin mesylate may be safely co-administered with compounds that are CYP3A4 inducers.


Assuntos
Antimitóticos/farmacocinética , Inibidores Enzimáticos/administração & dosagem , Furanos/farmacocinética , Cetonas/farmacocinética , Neoplasias/metabolismo , Rifampina/administração & dosagem , Administração Oral , Adulto , Idoso , Antimitóticos/administração & dosagem , Área Sob a Curva , Povo Asiático , Interações Medicamentosas , Feminino , Furanos/administração & dosagem , Humanos , Cetonas/administração & dosagem , Masculino , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Pessoa de Meia-Idade , População Branca
8.
J Minim Invasive Gynecol ; 20(6): 853-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24183277

RESUMO

STUDY OBJECTIVE: To compare operating time, intraoperative blood loss, postoperative analgesia, and length of hospital stay using ultrasonic shears vs traditional suture ligature in vaginal hysterectomy. DESIGN: Randomized controlled trial (Canadian Task Force classification I). SETTING: Gynecology units within a single health network, university hospital. PATIENTS: Forty women requiring vaginal hysterectomy because of benign disease. INTERVENTIONS: Vaginal hysterectomy performed using either ultrasonically activated shears (USS) or traditional suture ligatures. MEASUREMENTS AND MAIN RESULTS: Twenty-one patients were randomized to the USS arm, and 19 patients to the traditional suture ligature arm. Patient characteristics were comparable. Mean (SD) hysterectomy time and was similar in both the USS and traditional arms, 28.66 (4.0) minutes vs 32.37 (3.18) minutes (p = .47), as was total operating time, 97.38 (8.9) minutes vs 91.63 (7.69) minutes (p = .63). Operative blood loss was significantly decreased in the USS group: 62.63 (12.46) mL vs 136.05 (21.54) mL (p = .006). There was, however, no significant change in hemoglobin concentration between the 2 groups: 19.53 (1.79) g/L vs -16.72 (2.5) g/L. There was no significant difference in mean oxycodone use: 9.29 (2.66) mg vs 8.06 (3.19) mg (p = .77). Length of hospital stay was similar in both groups: 58.98 (3.27) hours vs 60.05 (6.48) hours (p = .88). There was no significant difference in overall complication rates between the groups. CONCLUSION: Although the Harmonic scalpel system, compared with the traditional suture ligation method, seems to be a safe alternative for securing the pedicles in vaginal hysterectomy, it offers no benefit insofar as operative time, reduction in clinically significant blood loss, and analgesic requirements.


Assuntos
Histerectomia Vaginal/métodos , Ligadura/métodos , Técnicas de Sutura , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Suturas , Resultado do Tratamento
9.
Acta Neurochir (Wien) ; 155(5): 823-36, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23430231

RESUMO

BACKGROUND: Accuracy of electrode placement is an important determinant of outcome following deep brain stimulation (DBS) surgery. Data on accuracy of electrode placement into the globus pallidum interna (GPi) in paediatric patients is limited, particularly those with non-primary dystonia who often have smaller GPi. Pallidal DBS is known to be more effective in the treatment of primary dystonia compared with secondary dystonia. OBJECTIVES: We aimed to determine if accuracy of pallidal electrode placement differed between primary, secondary and NBIA (neuronal degeneration and brain iron accumulation) associated dystonia and how this related to motor outcome following surgery. METHODS: A retrospective review of a consecutive cohort of children and young people undergoing DBS surgery in a single centre. Fused in frame preoperative planning magnetic resonance imaging (MRI) and postoperative computed tomography (CT) brain scans were used to determine the accuracy of placement of DBS electrode tip in Leskell stereotactic system compared with the planned target. The differences along X, Y, and Z coordinates were calculated, as was the Euclidean distance of electrode tip from the target. The relationship between proximity to target and change in Burke-Fahn-Marsden Dystonia Rating Scale at 1 year was also measured. RESULTS: Data were collected from 88 electrodes placed in 42 patients (14 primary dystonia, 18 secondary dystonia and 10 NBIA associated dystonia). Median differences between planned target and actual position were: left-side X-axis 1.05 mm, Y-axis 0.85 mm, Z-axis 0.94 mm and Euclidean difference 2.04 mm; right-side X-axis 1.28 mm, Y-axis 0.70 mm, Z-axis 0.70 mm and Euclidean difference 2.45 mm. Accuracy did not differ between left and right-sided electrodes. No difference in accuracy was seen between primary, secondary or NBIA associated dystonia. Dystonia reduction at 1 year post surgery did not appear to relate to proximity of implanted electrode to surgical target across the cohort. CONCLUSIONS: Accuracy of surgical placement did not differ between primary, secondary or NBIA associated dystonia. Decreased efficacy of pallidal DBS in secondary and NBIA associated dystonia is unlikely to be related to difficulties in achieving the planned electrode placement.


Assuntos
Estimulação Encefálica Profunda , Distonia/terapia , Eletrodos Implantados , Adolescente , Criança , Pré-Escolar , Estimulação Encefálica Profunda/métodos , Globo Pálido , Humanos , Imageamento por Ressonância Magnética/métodos , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodos , Adulto Jovem
10.
Heart ; 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36104218

RESUMO

Magnetic Resonance Imaging (MRI) is increasingly a fundamental component of the diagnostic pathway across a range of conditions. Historically, the presence of a cardiac implantable electronic device (CIED) has been a contraindication for MRI, however, development of MR Conditional devices that can be scanned under strict protocols has facilitated the provision of MRI for patients. Additionally, there is growing safety data to support MR scanning in patients with CIEDs that do not have MR safety labelling or with MR Conditional CIEDs where certain conditions are not met, where the clinical justification is robust. This means that almost all patients with cardiac devices should now have the same access to MRI scanning in the National Health Service as the general population. Provision of MRI to patients with CIED, however, remains limited in the UK, with only half of units accepting scan requests even for patients with MR Conditional CIEDs. Service delivery requires specialist equipment and robust protocols to ensure patient safety and facilitate workflows, meanwhile demanding collaboration between healthcare professionals across many disciplines. This document provides consensus recommendations from across the relevant stakeholder professional bodies and patient groups to encourage provision of safe MRI for patients with CIEDs.

11.
Artigo em Inglês | MEDLINE | ID: mdl-33762314

RESUMO

INTRODUCTION: It is increasingly recognized that type 2 diabetes (T2D) is a heterogenous disease with ethnic variations. Differences in insulin secretion, insulin resistance and ectopic fat are thought to contribute to these variations. Therefore, we aimed to compare postprandial insulin secretion and the relationships between insulin secretion, insulin sensitivity and pancreatic fat in men of black West African (BA) and white European (WE) ancestry. RESEARCH DESIGN AND METHODS: A cross-sectional, observational study in which 23 WE and 23 BA men with normal glucose tolerance, matched for body mass index, underwent a mixed meal tolerance test with C peptide modeling to measure beta cell insulin secretion, an MRI to quantify intrapancreatic lipid (IPL), and a hyperinsulinemic-euglycemic clamp to measure whole-body insulin sensitivity. RESULTS: Postprandial insulin secretion was lower in BA versus WE men following adjustment for insulin sensitivity (estimated marginal means, BA vs WE: 40.5 (95% CI 31.8 to 49.2) × 103 vs 56.4 (95% CI 48.9 to 63.8) × 103 pmol/m2 body surface area × 180 min, p=0.008). There was a significantly different relationship by ethnicity between IPL and insulin secretion, with a stronger relationship in WE than in BA (r=0.59 vs r=0.39, interaction p=0.036); however, IPL was not a predictor of insulin secretion in either ethnic group following adjustment for insulin sensitivity. CONCLUSIONS: Ethnicity is an independent determinant of beta cell function in black and white men. In response to a meal, healthy BA men exhibit lower insulin secretion compared with their WE counterparts for their given insulin sensitivity. Ethnic differences in beta cell function may contribute to the greater risk of T2D in populations of African ancestry.


Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Negro ou Afro-Americano , Estudos Transversais , Humanos , Insulina , Masculino
12.
Eur J Endocrinol ; 182(1): 91-101, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31721724

RESUMO

OBJECTIVES: In men of black west African (BAM) and white European (WEM) ethnicity, we aimed to (1) compare adipose tissue, peripheral and hepatic insulin sensitivity and (2) investigate associations between ectopic fat and insulin sensitivity by ethnicity. DESIGN AND METHODS: In overweight BAM (n = 21) and WEM (n = 23) with normal glucose tolerance, we performed a two-step hyperinsulinaemic-euglycaemic clamp with infusion of [6,6 2H2]-glucose and [2H5]-glycerol to measure whole body, peripheral, hepatic and adipose tissue insulin sensitivity (lipolysis). Visceral adipose tissue (VAT), intrahepatic lipids (IHL) and intramyocellular (IMCL) lipids were measured using MRI and spectroscopy. Associations between insulin sensitivity and ectopic fat were assessed using Pearson's correlation coefficient by ethnicity and regression analysis. RESULTS: There were no ethnic differences in whole body or tissue-specific insulin sensitivity (all P > 0.05). Suppression of lipolysis was inversely associated with VAT and IHL in WEM but not BAM (VAT: WEM r = -0.68, P < 0.01; BAM r = 0.07, P = 0.79. IHL: WEM r = -0.52, P = 0.01; BAM r = -0.12, P = 0.63). IMCL was inversely associated with skeletal muscle insulin sensitivity in WEM but not BAM (WEM r = -0.56, P < 0.01; BAM r = -0.09, P = 0.75) and IHL was inversely associated with hepatic insulin sensitivity in WEM but not BAM (WEM r = -0.53, P = 0.02; BAM r = -0.13, P = 0.62). CONCLUSIONS: Ectopic fat deposition may play a lesser role in reducing insulin sensitivity in men of black African ethnicity and may not be driven by lipolysis. Resistance to storing VAT, IHL and IMCL may enable men of black African ethnicity to maintain comparable insulin sensitivity to white Europeans.


Assuntos
Resistência à Insulina/fisiologia , Sobrepeso/metabolismo , Adolescente , Adulto , Idoso , População Negra , Feminino , Humanos , Gordura Intra-Abdominal/metabolismo , Gordura Intra-Abdominal/fisiologia , Masculino , Pessoa de Meia-Idade , Obesidade/metabolismo , Obesidade/fisiopatologia , Sobrepeso/fisiopatologia , População Branca , Adulto Jovem
13.
Diabetes Res Clin Pract ; 156: 107866, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31542318

RESUMO

AIMS: We aimed to assess ethnic differences in visceral adipose tissue (VAT), intrahepatic (IHL), intrapancreatic (IPL) and intramyocellular lipids (IMCL) between healthy white European (WE) and black west African (BWA) men. METHODS: 23 WE and 20 BWA men underwent Dixon-magnetic resonance imaging to quantify VAT, IHL and IPL; and proton-magnetic resonance spectroscopy to quantify IMCL. Insulin sensitivity and beta-cell function were determined using homeostasis model assessment (HOMA-2). RESULTS: BWA men exhibited significantly lower VAT (P = 0.021) and IHL (P = 0.044) than WE men, but comparable IPL (P = 0.92) and IMCL (P = 0.87). VAT was associated with IPL in both ethnicities (WE: P < 0.001; BWA: P = 0.001) but the relationship with IHL differed by ethnicity (Pinteraction = 0.018) and was only significant in WE men (WE: P < 0.001; BWA: P = 0.36). All ectopic fat depots inversely associated with insulin sensitivity and positively associated with beta-cell function in WE but not BWA men. CONCLUSIONS: Lower VAT and IHL, and their lack of interrelation, in BWA men suggests ethnic differences exist in the mechanisms of ectopic fat deposition. The lack of association between ectopic fat with insulin sensitivity and beta-cell function in BWA men may indicate a lesser role for ectopic fat in the development of type 2 diabetes mellitus in black populations.


Assuntos
Negro ou Afro-Americano/etnologia , Gordura Intra-Abdominal/fisiopatologia , Adolescente , Adulto , Idoso , Etnicidade , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
15.
J Clin Endocrinol Metab ; 104(4): 1201-1210, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30407535

RESUMO

CONTEXT: Intrapancreatic lipid (IPL) has been linked to ß-cell dysfunction. Black populations disproportionately develop type 2 diabetes (T2D) and show distinctions in ß-cell function compared with white populations. OBJECTIVE: We quantified IPL in white European (WE) and black West African (BWA) men with early T2D and investigated the relationships between IPL and ß-cell insulin secretory function (ISF). DESIGN, SETTING, AND PARTICIPANTS: We performed a cross-sectional assessment of 18 WE and 19 BWA middle-age men with early T2D as part of the South London Diabetes and Ethnicity Phenotyping study. MAIN OUTCOME MEASURES: The participants underwent Dixon MRI to determine IPL in the pancreatic head, body, and tail and subcutaneous and visceral adipose tissue volumes. Modeled first- and second-phase ISFs were comprehensively determined using C-peptide measurements during a 3-hour meal tolerance test and a 2-hour hyperglycemic clamp test. RESULTS: The WE men had greater mean IPL levels compared with BWA men (P = 0.029), mainly owing to greater IPL levels in the pancreatic head (P = 0.009). The mean IPL level was inversely associated with orally stimulated first-phase ISF in WE but not BWA men (WE, r = -0.554, P = 0.026; BWA, r = -0.183, P = 0.468). No association was found with orally stimulated second-phase ISF in either WE or BWA men. No associations were found between the mean IPL level and intravenously stimulated ISF. CONCLUSIONS: The IPL levels were lower in BWA than WE men with early T2D, and the lack of inverse association with first-phase ISF in BWA men indicates that IPL might be a less important determinant of the development of T2D in BWA than in WE men.


Assuntos
Diabetes Mellitus Tipo 2/etnologia , Disparidades nos Níveis de Saúde , Células Secretoras de Insulina/metabolismo , Lipídeos/análise , Pâncreas/química , Idoso , População Negra/estatística & dados numéricos , Estudos Transversais , Diabetes Mellitus Tipo 2/diagnóstico por imagem , Diabetes Mellitus Tipo 2/fisiopatologia , Humanos , Insulina/metabolismo , Gordura Intra-Abdominal/diagnóstico por imagem , Londres , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Pâncreas/diagnóstico por imagem , Pâncreas/fisiopatologia , População Branca/estatística & dados numéricos
16.
Br J Radiol ; 91(1082): 20170005, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29076743

RESUMO

OBJECTIVES: This study evaluates the use of balanced steady-state free precession MRI (bSSFP-MRI) in the diagnostic work-up of patients undergoing interventional deep venous reconstruction (I-DVR). Intravenous digital subtraction angiography (IVDSA) was used as the gold-standard for comparison to assess disease extent and severity. METHODS: A retrospective comparison of bSSFP-MRI to IVDSA was performed in all patients undergoing both examinations for treatment planning prior to I-DVR. The severity of disease in each venous segment was graded by two board-certified radiologists working independently, according to a predetermined classification system. RESULTS: In total, 44 patients (225 venous segments) fulfilled the inclusion criteria. A total of 156 abnormal venous segments were diagnosed using bSSFP-MRI compared with 151 using IVDSA. The prevalence of disease was higher in the iliac and femoral segments (range, 79.6-88.6%). Overall sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and the diagnostic ratio for bSSFP-MRI were 99.3%, 91.9%, 12.3, 0.007 and 1700, respectively. CONCLUSION: This study supports the use of non-contrast balanced SSFP-MRI in the assessment of the deep veins of the lower limb prior to I-DVR. The technique offers an accurate, fast and non-invasive alternative to IVDSA. Advances in Knowledge: Although balanced SSFP-MRI is commonly used in cardiac imaging, its use elsewhere is limited and its use in evaluating the deep veins prior to interventional reconstruction is not described. Our study demonstrates the usefulness of this technique in the work-up of patients awaiting interventional venous reconstruction compared with the current gold standard.


Assuntos
Angiografia Digital , Extremidade Inferior/irrigação sanguínea , Imageamento por Ressonância Magnética , Síndrome Pós-Trombótica/diagnóstico por imagem , Veias/diagnóstico por imagem , Trombose Venosa/diagnóstico por imagem , Adolescente , Adulto , Idoso , Meios de Contraste , Feminino , Humanos , Iohexol , Funções Verossimilhança , Extremidade Inferior/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Sensibilidade e Especificidade , Ácidos Tri-Iodobenzoicos , Adulto Jovem
17.
Br J Radiol ; 91(1081): 20170577, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29076749

RESUMO

OBJECTIVE: Application of whole body diffusion-weighted MRI (WB-DWI) for oncology are rapidly increasing within both research and routine clinical domains. However, WB-DWI as a quantitative imaging biomarker (QIB) has significantly slower adoption. To date, challenges relating to accuracy and reproducibility, essential criteria for a good QIB, have limited widespread clinical translation. In recognition, a UK workgroup was established in 2016 to provide technical consensus guidelines (to maximise accuracy and reproducibility of WB-MRI QIBs) and accelerate the clinical translation of quantitative WB-DWI applications for oncology. METHODS: A panel of experts convened from cancer centres around the UK with subspecialty expertise in quantitative imaging and/or the use of WB-MRI with DWI. A formal consensus method was used to obtain consensus agreement regarding best practice. Questions were asked about the appropriateness or otherwise on scanner hardware and software, sequence optimisation, acquisition protocols, reporting, and ongoing quality control programs to monitor precision and accuracy and agreement on quality control. RESULTS: The consensus panel was able to reach consensus on 73% (255/351) items and based on consensus areas made recommendations to maximise accuracy and reproducibly of quantitative WB-DWI studies performed at 1.5T. The panel were unable to reach consensus on the majority of items related to quantitative WB-DWI performed at 3T. CONCLUSION: This UK Quantitative WB-DWI Technical Workgroup consensus provides guidance on maximising accuracy and reproducibly of quantitative WB-DWI for oncology. The consensus guidance can be used by researchers and clinicians to harmonise WB-DWI protocols which will accelerate clinical translation of WB-DWI-derived QIBs.


Assuntos
Imagem de Difusão por Ressonância Magnética/normas , Oncologia/normas , Neoplasias/diagnóstico por imagem , Imagem Corporal Total/normas , Humanos , Controle de Qualidade , Reino Unido
18.
Semin Ultrasound CT MR ; 37(4): 352-7, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27342899

RESUMO

As an integrated system, hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) is able to provide simultaneously complementary high-resolution anatomic, molecular, and functional information, allowing comprehensive cancer phenotyping in a single imaging examination. In addition to an improved patient experience by combining 2 separate imaging examinations and streamlining the patient pathway, the superior soft tissue contrast resolution of MRI and the ability to acquire multiparametric MRI data is advantageous over computed tomography. For gastrointestinal cancers, this would improve tumor staging, assessment of neoadjuvant response, and of the likelihood of a complete (R0) resection in comparison with positron emission tomography or computed tomography.


Assuntos
Neoplasias Gastrointestinais/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Imagem Multimodal , Tomografia por Emissão de Pósitrons/métodos , Meios de Contraste , Neoplasias Gastrointestinais/patologia , Humanos , Gradação de Tumores , Invasividade Neoplásica , Estadiamento de Neoplasias , Fenótipo , Compostos Radiofarmacêuticos
19.
Diagnostics (Basel) ; 5(3): 333-57, 2015 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-26854157

RESUMO

Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging.

20.
Insights Imaging ; 3(1): 11-21, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22695995

RESUMO

Magnetic resonance cholangiopancreatography (MRCP) is a technique that has evolved over the past two decades. It continues to have a fundamental role in the non-invasive investigation of many pancreatico-biliary disorders. The purpose of this review is to summarise the key concepts behind MRCP, the different techniques that are currently employed (including functional and secretin-stimulated MRCP), the pitfalls the reader should be aware of, and the main clinical indications for its use.

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