磁共振水成像对脊柱疾病诊断中的应用价值

目的:探讨磁共振水成像技术对脊柱疾病诊断的应用价值。方法:采用快速高级自旋回波(FASE)、重T2WI及脂肪抑制序列对300例病人检查行磁共振椎管水成像(MRmyelography,MRM)。结果:MRM显示正常25例,MRM异常275例,清楚显示原发病变与邻近脊髓腔、脊髓、神经根的相关关系。结论:MRM具有无创伤、无辐射、速度快,不需对比剂,患者易接受的特点。MRM与常规MRI图像结合可获得全面、客观的病变信息,MRM图像可取代X线脊髓造影和CT脊髓造影。     

Cryptococcal neuroradiological lesions correlate with severity during cryptococcal meningoencephalitis in HIV-positive patients in the HAART era

Cryptococcal meningoencephalitis has an overall global mortality rate of 20% in AIDS patients despite antifungals. There is a need for additional means of precise assessment of disease severity. We thus studied the radiological brain images available from 62 HIV-positive patients with cryptococcocal meningoencephalitis to analyse the brain lesions associated with cryptococcosis in relationship with disease severity, and the respective diagnostic contribution of magnetic resonance (MR) versus computed tomography (CT). In this retrospective multicenter analysis, two neuroradiologists blindly reviewed the brain imaging. Prospectively acquired clinical and mycological data were available at baseline and during follow-up. Baseline images were abnormal on 92% of the MR scans contrasting with 53% of the CT scans. MR/CT cryptococcosis-related lesions included mass(es) (21%/9%), dilated perivascular spaces (46%/5%) and pseudocysts (8%/4%). The presence compared to absence of cryptococcosis-related lesions was significantly associated with high serum (78% vs. 42%, p = 0.008) and CSF (81% vs. 50%, p = 0.024) antigen titers, independently of neurological abnormalities. MR detected significantly more cryptococcosis-related lesions than CT for 17 patients who had had both investigations (76% vs. 24%, p = 0.005). In conclusion, MR appears more effective than CT for the evaluation of AIDS-associated cerebral cryptococcosis. Furthermore, brain imaging is an effective tool to assess the initial disease severity in this setting. Given this, we suggest that investigation for cryptococcosis-related lesions is merited, even in the absence of neurological abnormality, if a high fungal burden is suspected on the basis of high serum and/or CSF antigen titers.     

CT 与X线诊断肠梗阻的临床价值探讨

目的：探讨腹部X 线与CT 扫描鉴别急性肠梗阻的准确性,为临床诊断提供参考。方法：选取2011年8 月-2013 年8 月我院 收治的66 例急性肠梗阻患者的临床资料进行回顾分析。所有患者均经手术活检或病理诊断证实为急性肠梗阻。术后患者均行腹 部X 线及CT扫描检查,对两种方法判断肠梗阻的发生、梗阻部位、类型及病因与手术病理结果进行比较,评价并分析两种检查 方法的准确率。结果：66 例肠梗阻患者中,X线检出率为89.39%,CT 检出率为95.45%。X 线诊断小肠梗阻准确率为72.10%,CT 为86.05%;X线诊断结肠梗阻准确率为69.57%,CT 为86.96%。X线诊断肿瘤准确率为69.57%,CT 为86.96%;X线诊断肠粘连 准确率为67.86%,CT 为82.14%;X 线诊断肠套叠准确率为60.00%,CT 为80.00%;X线诊断单纯性机械性肠梗阻准确率为78.72%,CT为82.98%;X线诊断绞窄性肠梗准确率为73.68%,CT 为78.95 %。CT 对肠梗阻部位、病因及类型的诊断准确率高于腹部X 线片,差异具有统计学意义(P<0.05)。结论：腹部X 线与CT 用于诊断急性肠梗阻具有较高的准确率,但CT 对于肠梗阻部位、梗阻类型及梗阻病因的诊断优于X线片。     

X-ray study in infants of the first year of life who had congenital heart diseases: traditions, specific features, new capacities

The paper analyzes the experience with ultrafast computed tomography (CT) used for 4 years to examine 178 babies with complicated congenital heart diseases (CHD), admitted to A.N. Bakulev Research Center of Cardiovascular Surgery, Russian Academy of Medical Sciences, for surgical treatment. It shows the comparative capacities of X-ray study, CT, and catheterized angiography in the diagnosis of CHD and concomitant lung diseases in patients of the first year of life in terms of the physiological and anatomic features of the course of disease. A complex of noninvasive radiation studies is shown to be of high informative value in evaluating the actual anatomy of complicated cardiac and pulmonary anomalies and in detecting the predictors of respiratory complications. The introduction of CT into the traditional algorithm of preoperative examination of patients with CHD has resulted in a considerable reduction in intracardiac diagnostic studies in neonates and infants of the first year of life.     

Magnetic resonance cholangiopancreatography and a problem in diagnosis of hepatopancreatoduodenal diseases

Based on the findings of 54 magnetic resonance studies, the authors used 19 of them authors to study the types of normalcy. A role of the new noninvasive technique magnetic resonance cholangiopancreatography (MRCPG) in the diagnosis of hepatopancreatoduodenal diseases is assessed. The potentialities of MRCPG in the detection of most common diseases and malformations of the biliary system are demonstrated. Comparative studies of MRCPG and endoscopic retrograde cholangiopancreatography (ERCPG) were conducted in 18 cases. The paper shows a methodological approach to MRCPG and analyzes the studies by describing the MR semiotics of major diseases. Emphasis is laid on how it is important to combine routine MRI and MRCPG in certain diagnostic situations. The authors consider that MRCPG is able to replace X-ray endoscopic studies and primarily ERCPG in diagnostic terms, by reserving their therapeutical functions for itself. MRCPG has great potentialities that, require further investigations and analysis.     

CT与X线诊断肠梗阻的临床价值探讨

目的：探讨腹部X线与CT扫描鉴别急性肠梗阻的准确性,为临床诊断提供参考。方法：选取2011年8月-2013年8月我院收治的66例急性肠梗阻患者的临床资料进行回顾分析。所有患者均经手术活检或病理诊断证实为急性肠梗阻。术后患者均行腹部X线及CT扫描检查,对两种方法判断肠梗阻的发生、梗阻部位、类型及病因与手术病理结果进行比较,评价并分析两种检查方法的准确率。结果：66例肠梗阻患者中,X线检出率为89．39％,CT检出率为95．45％。X线诊断小肠梗阻准确率为72．10％,CT为86．05％;X线诊断结肠梗阻准确率为69．57％,CT为86．96％。X线诊断肿瘤准确率为69．57％,CT为86．96％;X线诊断肠粘连准确率为67．86％,CT为82．14％;X线诊断肠套叠准确率为60．00％,CT为80．00％;X线诊断单纯性机械性肠梗阻准确率为78．72％,CT为82．98％;X线诊断绞窄性肠梗准确率为73．68％,CT为78．95％。CT对肠梗阻部位、病因及类型的诊断准确率高于腹部X线片,差异具有统计学意义（P〈0．05）。结论：腹部X线与CT用于诊断急性肠梗阻具有较高的准确率,但CT对于肠梗阻部位、梗阻类型及梗阻病因的诊断优于X线片。     

Current complex noninvasive diagnosis of parathyroid tumors

The diagnosis of bulky formations of the parathyroid glands (PTG) has become possible since current high-resolution techniques of visualization, such as ultrasound study (USS), computed tomography (CT), magnetic resonance imaging (MRI), were introduced into practice. The presence of clinical and/or laboratory signs of hyperparathyroidism (HPT) is a signal to initiate a goal-oriented search for abnormal PTG formations. The complex diagnosis of HPT involves the methods of detecting osteoporosis ranging from routine X-ray study of the hand and foot to more in-depth techniques: dichromatic X-ray absorptiometry (DXA) and quantitative CT (QCT). USS is an excellent method for screening if abnormal PTC changes are suspected; however, negative USS results in the presence of clinical and/or laboratory signs of HPT should not stop a diagnostic search. CT with intravenous contrast bolus specifies the site and structure of an formation, has some advantage in detecting retrosternal tumors. Due to its high tissue contrast, three-dimensional images, none ionizing radiation and osseous structural artefacts, MRI becomes a preferable tool for studying PTG when they are typically or atypically located. Needle biopsy is required when noninvasive methods cannot characterize the pattern of an abnormal PTG formation properly or their results are contradictory.     

Descending myelography with water-soluble contrast agents using methods of lateral puncture of the great occipital cistern]

A method of lateral puncture of the great occipital cistern for descending myelography with water soluble contrast substances was employed. It was used in 150 neurosurgical inpatients aged 4 to 70 with various diseases of the spinal marrow and its coats. A new water soluble drug iopamidol-200 (or 300) (Bracco, Italy) was used for diagnosis of spinal tumors. The drug dosage was worked out for adults as well as for children. A study was made of possible side-effects on a vast clinical material (80 patients). The new contrast substance iopamidol possesses better tolerance by patients and better roentgenocontrast properties than amipack.     

Development and application of a multimodal contrast agent for SPECT/CT hybrid imaging

Hybrid or multimodality imaging is often applied in order to take advantage of the unique and complementary strengths of individual imaging modalities. This hybrid noninvasive imaging approach can provide critical information about anatomical structure in combination with physiological function or targeted molecular signals. While recent advances in software image fusion techniques and hybrid imaging systems have enabled efficient multimodal imaging, accessing the full potential of this technique requires development of a new toolbox of multimodal contrast agents that enhance the imaging process. Toward that goal, we report the development of a hybrid probe for both single photon emission computed tomography (SPECT) and X-ray computed tomography (CT) imaging that facilitates high-sensitivity SPECT and high spatial resolution CT imaging. In this work, we report the synthesis and evaluation of a novel intravascular, multimodal dendrimer-based contrast agent for use in preclinical SPECT/CT hybrid imaging systems. This multimodal agent offers a long intravascular residence time (t(1/2) = 43 min) and sufficient contrast-to-noise for effective serial intravascular and blood pool imaging with both SPECT and CT. The colocalization of the dendritic nuclear and X-ray contrasts offers the potential to facilitate image analysis and quantification by enabling correction for SPECT attenuation and partial volume errors at specified times with the higher resolution anatomic information provided by the circulating CT contrast. This may allow absolute quantification of intramyocardial blood volume and blood flow and may enable the ability to visualize active molecular targeting following clearance from the blood.     

Atherosclerotic plaque imaging using phase-contrast X-ray computed tomography

Reliable, noninvasive imaging modalities to characterize plaque components are clinically desirable for detecting unstable coronary plaques, which cause acute coronary syndrome. Although recent clinical developments in computed tomography (CT) have enabled the visualization of luminal narrowing and calcified plaques in coronary arteries, the identification of noncalcified plaque components remains difficult. Phase-contrast X-ray CT imaging has great potentials to reveal the structures inside biological soft tissues, because its sensitivity to light elements is almost 1,000 times greater than that of absorption-contrast X-ray imaging. Moreover, a specific mass density of tissue can be estimated using phase-contrast X-ray CT. Ex vivo phase-contrast X-ray CT was performed using a synchrotron radiation source (SPring-8, Japan) to investigate atherosclerotic plaque components of apolipoprotein E-deficient mice. Samples were also histologically analyzed. Phase-contrast X-ray CT at a spatial resolution of 10-20 mum revealed atherosclerotic plaque components easily, and thin fibrous caps were detected. The specific mass densities of these plaque components were quantitatively estimated. The mass density of lipid area was significantly lower (1.011 +/- 0.001766 g/ml) than that of smooth muscle area or collagen area (1.057 +/- 0.001407 and 1.080 +/- 0.001794 g/ml, respectively). Moreover, the three-dimensional assessment of plaques could provide their anatomical information. Phase-contrast X-ray CT can estimate the tissue mass density of atherosclerotic plaques and detect lipid-rich areas. It can be a promising noninvasive technique for the investigation of plaque components and detection of unstable coronary plaques.     

MRI和螺旋CT增强在肝脏占位性病变诊断中的价值比较

目的:对比分析MRI和螺旋CT增强在肝脏占位性病变诊断中的价值。方法:以2012年7月-2016年5月我院收治的临床考虑为肝脏占位性病变70例患者为研究对象,将70例患者根据入组先后顺序分为两组,35例行增强CT扫描,35例行动态增强MRI扫描,比较两组患者的病理诊断结果、病灶个数及直径、增强CT及MRI的诊断结果和检查过程中的不良反应及耐受性。结果:CT增强组和MRI增强组的肝脏占位性病变的病理诊断、病变类型、分布及病灶个数(71 vs 70)、病灶直径(2.25±2.01 cm vs2.19±1.98 cm)比较差异均无统计学意义(P0.05);以病理诊断结果为金标准,MRI增强组的总诊断符合率为85.71%,CT增强组的总诊断符合率为77.14%,MRI增强组的总诊断符合率高于CT增强组,但差异无统计学意义(P0.05);CT增强组共发生2例不良反应,均为轻度恶心,MRI增强组未出现造影剂不良反应,CT增强组的不良反应发生率(5.71%vs 0.00%)及视觉模拟评分法(VAS)评分(1.25 0.96分vs 0.71 0.56分)均显著高于MRI增强组(P0.05)。结论:CT增强和MRI增强扫描对于肝脏占位性病变的诊断均具有较高的临床价值,其中MRI增强扫描的安全性和耐受性更高,临床医师可根据患者的经济状态、身体状态等因素的综合评估,选择合适的检查手段,必要时可两者联合检查,以提高诊断的准确性。     

Analysis of TaqMan Array Cards Data by an Assumption-Free Improvement of the maxRatio Algorithm Is More Accurate than the Cycle-Threshold Method

Quantitative PCR diagnostic platforms are moving towards increased sample throughput, with instruments capable of carrying out thousands of reactions at once already in use. The need for a computational tool to reliably assist in the validation of the results is therefore compelling. In the present study, 328 residual clinical samples provided by the Public Health England at Addenbrooke''s Hospital (Cambridge, UK) were processed by TaqMan Array Card assay, generating 15 744 reactions from 54 targets. The amplification data were analysed by the conventional cycle-threshold (CT) method and an improvement of the maxRatio (MR) algorithm developed to filter out the reactions with irregular amplification profiles. The reactions were also independently validated by three raters and a consensus was generated from their classification. The inter-rater agreement by Fleiss'' kappa was 0.885; the agreement between either CT or MR with the raters gave Fleiss'' kappa 0.884 and 0.902, respectively. Based on the consensus classification, the CT and MR methods achieved an assay accuracy of 0.979 and 0.987, respectively. These results suggested that the assumption-free MR algorithm was more reliable than the CT method, with clear advantages for the diagnostic settings.     

High-Field Proton Magnetic Resonance Spectroscopy of a Swine Model for Axonal Injury

Abstract: A miniature swine model for diffuse brain injury has recently been developed that replicates the inertial loading conditions associated with rotational acceleration during automotive accidents. The swine model induces diffuse axonal pathology without macroscopic injury such as contusions and hematomas, thus affording a unique opportunity to study axonal injury with noninvasive techniques such as magnetic resonance imaging (MRI) and spectroscopy (MRS). In the present study, we evaluated this diffuse injury model with proton MRS, in vivo, using a high-field (4.0-T) MR scanner, since MRS has been demonstrated as a sensitive probe for detecting neurochemical abnormalities. Our study examined a region of the swine brain at timepoints before and after brain injury. Spectroscopic results indicate that N -acetylaspartate/creatine is diminished by at least 20% in regions of confirmed axonal pathology, whereas conventional MRI did not detect any abnormalities. These findings suggest that MRS has high sensitivity in diagnosing microscopic pathology following diffuse brain injury.     

Evaluation of size,morphology, concentration,and surface effect of gold nanoparticles on X-ray attenuation in computed tomography

Increasing attention has been focused on the use of nanostructures as contrast enhancement agents in medical imaging, especially in computed tomography (CT). To date, gold nanoparticles (GNPs) have been demonstrated to have great potential as contrast agents for CT imaging. This study was designed to evaluate any effect on X-ray attenuation that might result from employing GNPs with a variety of shapes, sizes, surface chemistries, and concentrations. Gold nanorods (GNRs) and spherical GNPs were synthesized for this application. X-ray attenuation was quantified by Hounsfield unit (HU) in CT. Our findings indicated that smaller spherical GNPs (13 nm) had higher X-ray attenuation than larger ones (60 nm) and GNRs with larger aspect ratio exhibited great effect on X-ray attenuation. Moreover, poly ethylene glycol (PEG) coating on GNRs declined X-ray attenuation as a result of limiting the aggregation of GNRs. We observed X-ray attenuation increased when mass concentration of GNPs was elevated. Overall, smaller spherical GNPs can be suggested as a better alternative to Omnipaque, a good contrast agent for CT imaging. This data can be also considered for the application of gold nanostructures in radiation dose enhancement where nanoparticles with high X-ray attenuation are applied.     

Transcutaneous electrical stimulation of the spinal cord: A noninvasive tool for the activation of stepping pattern generators in humans

A new method for the activation of spinal locomotor networks (SLN) in humans by transcutaneous electrical spinal cord stimulation (tESCS) has been described. The tESCS applied in the region of the T11-T12 vertebrae with a frequency of 5?C40 Hz elicited involuntary step-like movements in healthy subjects with their legs suspended in a gravity-neutral position. The amplitude of evoked step-like movements increased with increasing tESCS frequency. The frequency of evoked step-like movements did not depend on the frequency of tESCS. It was shown that the hip, knee, and ankle joints were involved in the evoked movements. It has been suggested that tESCS activates the SPG (SLN) through in part, via the dorsal roots that enter the spinal cord. tESCS can be used as a noninvasive method in rehabilitation of spinal pathology.     

Magnetic resonance imaging: present and future applications

Magnetic resonance (MR) imaging has created considerable excitement in the medical community, largely because of its great potential to diagnose and characterize many different disease processes. However, it is becoming increasingly evident that, because MR imaging is similar to computed tomography (CT) scanning in identifying structural disorders and because it is more costly and difficult to use, this highly useful technique must be judged against CT before it can become an accepted investigative tool. At present MR imaging has demonstrated diagnostic superiority over CT in a limited number of important, mostly neurologic, disorders and is complementary to CT in the diagnosis of certain other disorders. For most of the remaining organ systems its usefulness is not clear, but the lack of ionizing radiation and MR''s ability to produce images in any tomographic plane may eventually prove to be advantageous. The potential of MR imaging to display in-vivo spectra, multinuclear images and blood-flow data makes it an exciting investigative technique. At present, however, MR imaging units should be installed only in medical centres equipped with the clinical and basic research facilities that are essential to evaluate the ultimate role of this technique in the care of patients.     

Applications cliniques de l’imagerie hybride TEP-IRM

This paper reports the results of a preliminary study evaluating the feasibility and performance of a first whole body hybrid PET/MR scanner allowing sequential acquisition of co-registered MR and PET images. Sixty-two patients underwent whole body PET/MR imaging immediately after a clinical PET/CT. The hybrid device consists of a 3T MR and a time-of-flight PET scanner sharing a single bed allowing sequential acquisition of co-registered MR and PET images. Imaging protocols included a whole body MR used for attenuation correction of PET followed by high-resolution diagnostic MR. Image analysis included visual identification of radiotracer uptake in tumors and measurement of standardized uptake values (SUV) in tumoral lesions and in normal organs. PET images acquired in the PET/MR with a delay of 85 ± 22 minutes (range 49–120 minutes) showed perfect correlation and identical diagnostic quality compared to PET/CT. In 42 patients (68%), additional high-resolution MR sequences were acquired for clinical diagnosis showing excellent quality without any visually detectable artifacts. SUV measurements of tumor lesions obtained after correction with MR attenuation maps showed an excellent correlation with PET/CT (R² = 0.89 and R² = 0.95 for mean and maximum tissue uptake respectively). Due to the delay between the two studies, changes in tracer uptake biodistribution of normal tissue were observed. Our preliminary data show that whole body PET/MR is clinically applicable in oncologic patients yielding a comparable diagnostic performance as PET/CT with respect to lesion detection and localization.     

Magnetic Resonance Imaging for Diagnosis of Mandibular Involvement from Head and Neck Cancers: A Systematic Review and Meta-Analysis

Background

Diagnosis of mandibular involvement caused by head and neck cancers is critical for treatment. We performed a meta-analysis to determine the diagnostic efficacy of MR for distinguishing mandibular involvement caused by head and neck cancers.

Methods

Thirteen databases were searched electronically and hand-searching was also done. Two reviewers conducted study inclusion, data extractions, and quality assessment of the studies independently. Meta-disc 1.4 and STATA 11.0 were used to conduct the meta-analysis.

Results

16 studies involving a total of 490 participants underwent MR examinations and were accounted for in this meta-analysis. Among the included studies, 2 had high risk of bias, while the rest had unclear risk of bias. Meta-regression showed that the slight clinical and methodological heterogeneities did not influence the outcome (P>0.05). Meta-analysis indicated that the MR for the diagnosis of mandibular involvement had a pooled sensitivity (SEN) of 78%, specificity (SPE) of 83%, positive likelihood ratio (+LR) of 3.80, negative likelihood ratio (-LR) of 0.28, diagnostic odds ratio (DOR) of 28.94, area under curve (AUC) of 0.9110, and Q* of 0.8432. Two studies detected the diagnostic efficacy of MR for the mandibular medullar invasion, and only one study reported the inferior alveolar canal invasion, which made it impossible to include it in our meta-analysis. In comparing to CT, MR had a higher SEN without statistical significance (P = 0.08), but a significantly lower SPE (P = 0.04). The synthesized diagnostic efficacy (AUC and Q*) on mandibular involvement was similar between the two modalities (P>0.05).

Conclusions

Present clinical evidence showed that MR had an acceptable diagnostic value in detecting mandibular involvement caused by head and neck cancers. MR exceeded CT in diagnosing patients with mandibular invasion (higher sensitivity than CT) but was less efficacious to exclude patients without the mandibular invasion (lower specificity than CT).     

New concepts in characterization of ischemically injured myocardium by MRI

New concepts regarding the assessment of ischemic myocardial injuries have been addressed in this Minireview using magnetic resonance imaging (MRI). MRI, with its different techniques, brings not only anatomic, but also physiologic, information on ischemic heart disease. It has the ability to measure identical parameters in preclinical and clinical studies. MRI techniques provide the ideal package for repeated and noninvasive assessment of myocardial anatomy, viability, perfusion, and function. MR contrast agents can be applied in a variety of ways to improve MRI sensitivity for detecting and assessing ischemically injured myocardium. With MR contrast agents protocol, it becomes possible to identify ischemic, acutely infarcted, and peri-infarcted myocardium in occlusive and reperfused infarctions. Necrosis specific and nonspecific extracellular contrast-enhanced MRI has been used to assess myocardial viability. Contrast-enhanced perfusion MRI can explore the disturbances in large (angiography) and small coronary arteries (myocardial perfusion) as the underlying cause of myocardial dysfunction. Perfusion MRI has been used to measure myocardial perfusion (ml/min/g) and to demonstrate the difference in transmural myocardial blood flow. Information on no-reflow phenomenon is derived from dynamic changes in regional signal intensity after bolus injection of MR contrast agents. Another development is the near future availability of blood pool MR contrast agents. These agents are able to assess microvascular permeability and integrity and are advantageous in MR angiography (MRA) due to their persistence in the blood. Noncontrast-enhanced MRI such as cine MRI at rest/stress, sodium MRI, and MR spectroscopy also have the potential to noninvasively assess myocardial viability in patients. Futuristic applications for MRI in the heart will focus on identifying coronary artery disease at an early stage and the beneficial effects of new therapeutic agents such as intra-arterial gene therapy. MR techniques will have great future in the drug discovery process and in testing the effects of drugs on myocardial biochemistry, physiology, and morphology. Molecular imaging is going to bloom in this decade.