Measuring visceral fat with water-selective suppression methods (SPIR, SPAIR) in patients with metabolic syndrome.

We attempted to measure the area and volume of visceral fat using magnetic resonance (MR) imaging to avoid radiation exposure. We used water suppression-spectral attenuation with inversion recovery (WS-SPAIR) as prepulses and conducted T(1) high-resolution isotropic volume examination (THRIVE). Image processing software can be used to estimate the area and volume of fat and separate the fat and water signals at a visually optimal threshold in the MR image, which requires contrast enhancement between intestinal contents and visceral fat. In 14 volunteers, we evaluated WS-SPAIR and water suppression-spectral presaturation with inversion recovery (WS-SPIR) with respect to the relationship between the flip angle of THRIVE and signal contrast. We used flip angles of 5 degrees, 10 degrees, and 20 degrees. The minimum threshold that allowed exclusion of intestinal contents from the masked region was determined for each technique. The volume and area of the masked region, which included subcutaneous fat, were measured at the umbilicus level. Both volume and area increased with a smaller flip angle. The masked region was larger with WS-SPIR-THRIVE (flip angle 5 degrees ). The size of the masked region was determined according to the minimum threshold that allowed exclusion of the intestinal contents from the masked region, expressing the contrast between the intestinal contents and fat in a relative manner. It was speculated that by separating the signals at the threshold, WS-SPIR-THRIVE (flip angle 5 degrees) was a more suitable technique for measuring the area and volume of visceral fat.     

Hepatic fat fraction: MR imaging for quantitative measurement and display--early experience

The institutional review board approved this HIPAA-compliant study. After all five patients with nonalcoholic fatty liver disease signed a consent, they underwent magnetic resonance (MR) imaging for hepatic fat quantification. The purpose of this study was to develop a fast and accurate method to acquire and display quantitative maps of the percentage of hepatic fat. In-phase and out-of-phase gradient-echo MR imaging was performed with dual flip angles (70 degrees, 20 degrees) to resolve ambiguity of the dominant constituent. T2* corrections were also estimated and applied to generate color-coded maps of the estimated percentage of hepatic fat. MR imaging results were compared with biopsy results in two of five patients, and the technique was validated qualitatively and quantitatively with a water-oil phantom. Results of the phantom study confirmed that the dual-flip angle algorithm can be used to correctly identify the dominant constituent, allowing depiction of 0%-100% of fat content. The estimated liver fat fraction was comparable to quantitative fat measurements at biopsy in both patients (MR imaging, 18.3% +/- 2.8 [standard deviation] and 28.6% +/- 2.4, vs quantitative histopathologic analysis, 11.2% and 28.5%, respectively). Supplemental material: radiology.rsnajnls.org/cgi/content/full/2373041639/DC1     

MR and CT in the assessment of Poland syndrome.

Seven cases of Poland syndrome were investigated with CT and/or MR to assess the extent of the muscle abnormalities of the shoulder girdle. In all cases the absence of the sternocostal head of the pectoralis major was clearly shown, as were any associated abnormalities of the pectoralis minor, serratus anterior, and latissimus dorsi. The latissimus dorsi muscle has an important role in reconstructive surgery and can be difficult to assess clinically. Cross-sectional imaging with CT or MR will give useful information in patients with Poland syndrome requesting anterior axillary reconstruction and breast mound formation.     

MR imaging of the brain in fat embolism syndrome

Fat embolism syndrome (FES) is an uncommon but serious complication of traumatic injury and is frequently diagnostically challenging. In this paper, the authors present four patients who sustained lower extremity long bone injury and who had a normal Glasgow Coma Scale before orthopedic surgical intervention. However, postoperatively, significant neurological deterioration developed in these patients. While cranial computed tomography (CT) obtained immediately after surgery for acutely altered mental status was negative in two of the four patients, brain magnetic resonance imaging (MRI) demonstrated white and gray matter abnormalities accounting for the impaired neurological status in all cases. MRI findings in conjunction with clinical presentation established the diagnosis in all patients. MRI is indicated in any patient with orthopedic injuries who manifests an unexplained acute alteration in mental status, despite a normal head CT.     

Proton MR spectroscopy in metabolic assessment of musculoskeletal lesions

OBJECTIVE: The purposes of this review are to describe the principles and method of MR spectroscopy, summarize current published data on musculoskeletal lesions, and report additional cases that have been analyzed with recently developed quantitative methods. CONCLUSION: Proton MR spectroscopy can be used to identify key tissue metabolites and may serve as a useful adjunct to radiographic evaluation of musculoskeletal lesions. A pooled analysis of 122 musculoskeletal tumors revealed that a discrete choline peak has a sensitivity of 88% and specificity of 68% in the detection of malignancy. Modest improvements in diagnostic accuracy in 22 of 122 cases when absolute choline quantification was used encourage the pursuit of development of choline quantification methods.     

MR imaging evaluation of cardiovascular risk in metabolic syndrome

Metabolic syndrome has become an important public health problem and has reached epidemic proportions globally. Metabolic syndrome is characterized by a cluster of metabolic abnormalities in an individual, with insulin resistance as the main characteristic. The major adverse consequence of metabolic syndrome is cardiovascular disease, which is often already present without clinical signs or symptoms. In this early stage of disease, interventions (eg, lifestyle intervention, medication) can be used to prevent further cardiovascular deterioration or even to reverse cardiovascular disease. Therefore, risk stratification on an individual basis and early detection of cardiovascular disease are essential. Magnetic resonance (MR) imaging is a powerful tool for demonstrating cardiovascular risk factors in metabolic syndrome, such as increased fat depots and arterial stiffening. Furthermore, MR imaging is an established modality for the assessment of myocardial function. This review provides a summary of the current MR applications in metabolic syndrome and discusses how these MR techniques can be used to identify subclinical cardiovascular damage.     

Raeder syndrome: MR appearance.

A 40-year-old woman presented with symptoms compatible with Raeder syndrome. MR demonstrated narrowing of the left cavernous carotid artery. The high cervical portion of the left internal carotid artery was not identified. Angiography confirmed the narrowing of the cavernous carotid artery and showed marked and irregular stenosis of the distal cervical internal carotid artery. Involvement of the left sympathetic plexus and of ipsilateral cavernous sinus arteries is believed to have been the cause of the Raeder syndrome in this patient.     

Total and intraabdominal fat distribution in preadolescents and adolescents: measurement with MR imaging

PURPOSE: To prospectively correlate single- and multisection magnetic resonance (MR) imaging measurements with clinical measurements for assessment of abdominal adipose tissue volumes in healthy (control subjects), overweight, and diabetic overweight preadolescents and adolescents. MATERIALS AND METHODS: The study was approved by the institutional internal review board and was HIPAA compliant. Informed consent was obtained from parents, and assent was obtained from control subjects and patients. Thirty total study subjects (20 male, 10 female; age range, 10-18 years; mean, 14.5 years) underwent MR imaging, anthropometric measurement, and dual x-ray absorptiometry (DXA). A computer-assisted software program was used to quantify subcutaneous, visceral, and total abdominal adipose tissue volumes. Single-section measurements at disk space L4-L5 and whole-abdominal multisection measurements were compared, and each method was tested for correlations with anthropometric and DXA measurements with Spearman rho and Pearson correlation (r) coefficients. Single- and multisection image analyses required 5 and 25 minutes per subject, respectively. RESULTS: There was a high degree of correlation between single- and multisection MR imaging methods for measurement of subcutaneous (r = 0.97), visceral (r = 0.96), and total abdominal fat (r = 0.97). MR imaging fat measurements strongly correlated with anthropometric measurements (rho correlation range, 0.81-0.96; P 相似文献   

MR angiography with parallel acquisition for assessment of the visceral arteries: comparison with conventional MR angiography and 64-detector-row computed tomography

The purpose of the study was to retrospectively compare three-dimensional gadolinium-enhanced magnetic resonance angiography (conventional MRA) with MRA accelerated by a parallel acquisition technique (fast MRA) for the assessment of visceral arteries, using 64-detector-row computed tomography angiography (MDCTA) as the reference standard. Eighteen patients underwent fast MRA (imaging time 17 s), conventional MRA (29 s) and MDCTA of the abdomen and pelvis. Two independent readers assessed subjective image quality and the presence of arterial stenosis. Data were analysed on per-patient and per-segment bases. Fast MRA yielded better subjective image quality in all segments compared with conventional MRA (P = 0.012 for reader 1, P = 0.055 for reader 2) because of fewer motion-induced artefacts. Sensitivity and specificity of fast MRA for the detection of arterial stenosis were 100% for both readers. Sensitivity of conventional MRA was 89% for both readers, and specificity was 100% (reader 1) and 99% (reader 2). Differences in sensitivity between the two types of MRA were not significant for either reader. Interobserver agreement for the detection of arterial stenosis was excellent for fast (κ = 1.00) and good for conventional MRA (κ = 0.76). Thus, subjective image quality of visceral arteries remains good on fast MRA compared with conventional MRA, and the two techniques do not differ substantially in the grading of arterial stenosis, despite the markedly reduced acquisition time of fast MRA.     

MR imaging of fat

Fat has been used in many studies on magnetic resonance (MR) imaging as the tissue of reference in comparing regional signal intensities from various tissues using different imaging parameters. This is a retrospective study of 78 patients selected to assess the influence of different factors such as age, gender, obesity, and weight loss on the T1 and T2 relaxation parameters of fat in different areas of the body. The T1 values of fat were not influenced by the factors studied or by anatomic location of the fat. The T2 values were significantly lower in patients older than 65 years and in patients with significant weight loss caused by carcinoma or chronic disease. Nevertheless, these variations were small, with considerable overlap of the mean and rather large standard deviation values. In conclusion, fat is a valuable reference tissue for MR studies and is relatively uninfluenced by the factors studied.     

以反相位T_1加权肝脏MR信号强度丢失和内脏脂肪测量为生物标记研究肝脏脂肪变性

目的探讨MRI反相位T1WI以及脂肪抑制T2WI上肝脏信号强度(SI)丢失和体质量指数(BMI)是否与非酒精性脂肪性肝病(NAFLD)或丙型肝炎病毒(HCV)以及人类免疫     

Functional MR imaging evidence of altered functional activation in metabolic syndrome

BACKGROUND AND PURPOSE:MetS is a cluster of risk factors associated with significant cardiovascular morbidity and mortality and diminished cognitive function. Given that little is known about the early signs of brain vulnerability related to persistent metabolic dysfunction, we set out to determine whether cognitively healthy middle-aged individuals with MetS exhibit an altered cerebrovascular response to a cognitive challenge relative to those without MetS.MATERIALS AND METHODS:Forty neurologically healthy adults aged 40–60 years (19 with MetS and 21 healthy controls) performed a 2-back verbal working memory task during fMRI. We compared BOLD responses between the 2 groups in 8 a priori regions of interest previously shown to be associated with the 2-back in patients with cardiovascular disease.RESULTS:Age, education level, sex distribution, cognitive and emotional functioning, and task performance (accuracy and reaction time) were not different between the groups. Compared with healthy controls, individuals with MetS demonstrated a lower 2-back–related BOLD response in the right superior frontal gyrus, right superior parietal lobule, and left inferior parietal lobule.CONCLUSIONS:This study provides preliminary evidence that cognitively intact middle-aged individuals with MetS exhibit significant alterations in cerebrovascular response to a cognitive challenge. Our results also demonstrate that fMRI may identify early brain changes associated with MetS.

The number of elderly patients with dementia is expected to quadruple during the next 50 years.¹ In addition, a great number of older adults are projected to develop milder forms of cognitive impairment.¹ This trend is alarming because cognition is the most important determinant of health status, quality of life, and functional ability in older age.² Diminished cognitive capacity causes significant psychological, social, and economic hardship and adversely impacts a person''s ability to benefit from treatment for other medical problems.³ Due to the current paucity of treatments for dementia, management of treatable factors that place the brain at risk for subsequent cognitive decline is the primary line of defense, especially in cases in which vascular factors play a key role.^4–7MetS refers to a clustering of risk factors (ie, hypertension, hyperglycemia, dyslipidemia, and obesity) associated with increased cardiovascular morbidity and mortality.⁸ Growing evidence suggests that MetS is also harmful to cognition and that the cluster may have predictive value for cognitive decline over and above that of its individual components.^9–16 Older patients with MetS score lower on cognitive tests than age-matched healthy adults, particularly on measures of processing speed and executive functioning,¹⁷ cognitive domains that are associated with vascular cognitive impairment. Several studies have shown that middle-aged individuals with MetS are at higher risk of developing dementia in late life,¹⁸ yet accurate prediction of individual cognitive trajectories is difficult due to the low sensitivity of paper-and-pencil screening tests to subtle changes in intellectual functioning. Neuroimaging studies have shown promise in identifying individuals at risk for subsequent cognitive decline because these studies revealed that MetS is associated with early alterations in the structural integrity of cerebral white matter.^19–21BOLD fMRI has the potential to contribute further to our understanding of early cerebrovascular changes related to persistent metabolic dysfunction. Alterations in the BOLD response to cognitive challenges have been shown in cognitively asymptomatic patients with MS, HIV infection, and genetic risk for AD.^22–27 BOLD fMRI performed during cognitive tasks, therefore, can help elucidate the complex relationship between metabolic and vascular health, cerebrovascular support for cognitive function, and behavioral performance. An accurate model of the relationship between cerebrovascular health and persistent metabolic dysfunction at midlife could prove instrumental in increasing the success of broader efforts to prevent and treat vascular cognitive impairment.To our knowledge, no studies have examined functional neuroimaging in MetS. Accordingly, the aim of this study was to test the hypothesis that middle-aged adults with MetS would show altered patterns of brain activation (ie, BOLD responses) during a verbal working memory task. The chosen task requires selective attention, executive ability, and psychomotor speed, cognitive abilities typically affected in vascular-related cognitive impairment. As such, they may have particular relevance for MetS.     

Brain motion: measurement with phase-contrast MR imaging.

Brain motion during the cardiac cycle was measured prospectively in 10 healthy volunteers by using a phase-contrast cine magnetic resonance (MR) pulse sequence. The major cerebral lobes, diencephalon, brain stem, cerebellum, cerebellar tonsils, and spinal cord were studied. The overall pattern of brain motion showed caudal motion of the central structures (diencephalon, brain stem, and cerebellar tonsils) shortly after carotid systole, with concurrent cephalic motion of the major cerebral lobes and posterior cerebellar hemisphere. Peak brain displacement was in the range of 0.1-0.5 mm for all the structures except the cerebellar tonsils, which had greater displacement (0.4 mm +/- 0.16 [mean +/- standard error of mean]). Caudal motion of the central structures did not occur simultaneously but progressed in a caudal-to-rostral and posterior-to-anterior sequence, being seen first in the cerebellar tonsils and then later in the diencephalon (hypothalamus). Caudal motion of the low brain stem and cerebellar tonsil was simultaneous with caudal motion of cerebrospinal fluid in the cervical subarachnoid space. Oscillatory flow in the aqueduct was delayed compared with brain stem motion.     

代谢综合征患者腹内脂肪与心血管损害的关系

目的分析代谢综合征(MS)患者腹部脂肪分布及与心血管损害的关系。方法108例住院患者分为MS组(70例),高血压组(EH,22例),2型糖尿病组(T2DM,16例),计算三组腹内脂肪面积(VA)、腹壁脂肪面积(SA)及VA/SA,并分析它们与左室重量(LVM)、左室重量指数(LVMI)、颈动脉内膜中层厚度(IMT)、心肌缺血的关系。结果MS组患者较EH组和T2DM组VA显著增高(115·69±48·72cm2vs69·96±25·41cm2、55·96±29·75cm2,P均<0·01),VA≥80cm2组较VA<80cm2组LVM、LVMI均明显升高(186±70gvs155±44g,51±17g/m2vs44±13g/m2,P均<0·05),VA/SA≥0·75组较VA/SA<0·75组左、右侧IMT均明显增厚(0·90±0·41mmvs0·75±0·21mm,0·89±0·32mmvs0·77±0·21mm,P均<0·05),VA≥100cm2组心肌缺血率和缺血程度明显高于VA<100cm2组(P<0·05)。收缩压、舒张压、VA导致IMT增厚的OR值有显著意义。结论代谢综合征时腹内脂肪明显堆积,其堆积的程度与心血管损害的程度密切相关,且腹内脂肪是心血管损害的独立影响因素。     

Development of the pineal gland: measurement with MR.

PURPOSETo use MR imaging in the analysis of the size of the normal pineal gland in infants, children, and adolescents.METHODSWe retrospectively analyzed the size of the pineal gland in 249 patients (129 male and 120 female) aged 2 weeks to 20 years old. The maximum length (L), height (H), and width (W) of the gland were determined from a combination of sagittal, coronal, and axial MR images obtained on a 1.5-T scanner. The volume was calculated by using the formula 1/2 x L x H x W.RESULTSThe size of the pineal gland was significantly smaller in patients younger than 2 years old than in older patients. The size of the pineal gland increased until 2 years of age and remained stationary between the ages of 2 and 20 years. We found a large variation in size among all age groups. No difference in size was noted between males and females.CONCLUSIONThis study establishes norms for pineal gland size in infants younger than 2 years old and in children and adolescents 2 to 20 years old as detected with MR imaging. Knowledge of the size of the normal pineal gland is important in the detection of abnormalities of the pineal gland, particularly neoplasms.     

MR measurement of coronary blood flow.

The functional significance of coronary arterial stenosis can be evaluated by measuring the pharmacological flow reserve. Magnetic resonance (MR) imaging has a unique potential for noninvasive measurement of coronary blood flow and flow reserve in the native coronary artery and bypass graft. Restenosis after coronary balloon angioplasty and stenting in the left anterior descending artery can be detected noninvasively with serial MR measurements of the coronary flow reserve. Further refinement of the MR pulse sequences to improve spatial and temporal resolutions may permit accurate quantification of blood flow volume and flow reserve in all major coronary arterial branches. MR assessments of blood flow volume and flow pattern allow noninvasive detection of significant stenosis in the coronary artery bypass graft as well. By integrating MR blood flow measurement in the coronary sinus and cine MR assessment of left ventricular myocardial mass, altered myocardial micro-circulation in patients with diffuse myocardial diseases, such as hypertrophic cardiomyopathy and cardiac transplant, has been documented. J. Magn. Reson. Imaging 1999;10:728-733.