对比观察SWI与常规T1WI、T2WI、T2*WI显示肝硬化铁沉积结节的价值

目的评价SWI对肝硬化铁结节(SN)的检出率及其图像质量和检出结节数量,并与常规T1WI、T2WI、T2*WI对比。方法 128例肝硬化患者接受MR T1WI、T2WI、T2*WI和SWI。2名高年资放射科医师在SPIN图像处理软件上分别计算并比较4种图像上的SN检出率、SN与周围肝实质的信号强度比(SIR)、CNR,并计算SN的数量。结果 MR T1WI、T2WI、T2*WI和SWI的SN检出率分别为12.50%(16/128)、24.22%(31/128)、41.41%(53/128)和62.50%(80/128),SIR分别为0.85±0.16、0.58±0.17、0.50±0.20和0.36±0.21,CNR分别为9.15±5.79、9.77±5.49、11.49±4.57和13.93±5.64,SN的数量分别为(2.56±1.39)个/例、(16.27±12.32)个/例、(42.95±28.32)个/例和(72.31±62.99)个/例。SWI对SN的检出率明显高于T1WI、T2WI、T2*WI(χ2=26.86,P<0.05),SWI的SIR和CNR明显优于T1WI、T2WI、T2*WI(P均<0.05),SWI检出的SN数量明显多于T1WI、T2WI、T2*WI(P均<0.05)。结论 SWI在图像质量和SN的检出率以及检出数量上优于常规T1WI、T2WI和T2*WI,是检查肝硬化患者SN最敏感的方法,也是常规MR扫描的有益补充。     

T2-weighted magnetic resonance imaging of the liver: comparison of fat-suppressed GRASE with conventional spin echo, fat-suppressed turbo spin echo, and gradient echo at 1.0 T

BACKGROUND: Fat-suppressed T2-weighted gradient and spin echo (GRASE) magnetic resonance imaging in the liver was compared with three other sequences: conventional spin echo (SE), fat-suppressed and respiratory-triggered turbo SE (TSE), and fast field echo (FFE). METHODS: All sequences were applied in 48 prospective patients. Quantitative and qualitative analyses were performed. Biopsy or clinical follow-up established the final diagnosis of the lesions. RESULTS: GRASE showed the second best contrast-to-noise ratio, the second best artifact level, the same lesion detectability as TSE, and very short acquisition time. GRASE and TSE had the highest sensitivity, specificity, and accuracy. CONCLUSION: Fat-suppressed GRASE offers a fast and accurate method for imaging the liver.     

Cardiac phase contrast gradient echo MRI: measurement of myocardial wall motion in healthy volunteers and patients

A number of methods have been proposed for the noninvasive measurement of myocardial wall motion. The paper describes a strategy for assessing myocardial motion based on the sensitivity of the phase of the MR-signal to motion using a breath-hold phase contrast technique. A motion-sensitized and a motion-compensated MR-signal are measured during successive scans. The difference between the two MR-signals is used to calculate myocardial velocity in all three spatial dimensions. Postprocessing includes the transformation of the measured velocities into an internal coordinate system of the left ventricle. Also various presentation modes and further processing of the received velocity information are provided including calculation of global motion parameters. We examined 20 patients suffering from myocardial infarction. The overall left ventricular motion can be characterized by appropriate parameters describing the rotation and contraction or expansion, respectively. Regional motional disturbances are visualized using parametric images. Contrary to the highly consistent interindividual data in normal volunteers, patients showed significant localized motion deficits.     

T2WI及对比增强T1WI影像组学模型鉴别纤维型与非纤维型脑膜瘤

目的 观察T2WI及对比增强T1WI(T1C)影像组学模型鉴别纤维型与非纤维型脑膜瘤的价值。方法 回顾性分析423例经病理证实的单发低级别脑膜瘤患者,按7∶3比例分为训练集(n=296)和验证集(n=127);提取训练集T2WI和T1C中病灶3 376个影像组学特征,以SelectPercentile单因素分析法及最小绝对收缩和选择算子(LASSO)筛选最优影像组学特征,分别以分类器逻辑回归(LR)、支持向量机(SVM)、随机森林(RF)、线性SVC(LinearSVC)、自适应增强(Adaboost)及决策树(DT)构建鉴别纤维型与非纤维型脑膜瘤的影像组学模型,即模型_LR、模型_SVM、模型_RF、模型_linearSVC、模型_Adaboost及模型_DT,以验证集验证其效能。结果 基于T2WI和T1C共筛出13个最优影像组学特征,以之构建的模型_LR、模型_SVM、模型_RF、模型_linea...     

Myocardial T2* mapping: influence of noise on accuracy and precision

Background

Pixel-wise, parametric T2* mapping is emerging as a means of automatic measurement of iron content in tissues. It enables quick, intuitive interpretation and provides the potential benefit of spatial context between tissues. However, pixel-wise mapping uses much lower SNR data to estimate T2* when compared to region-based mapping thereby decreasing both its accuracy and precision. In this study, the effects that noise has on the precision and accuracy of pixel-wise T2* mapping were investigated and techniques to mitigate those effects are proposed.

Methods

To study precision across T2* mapping techniques, a pipeline to estimate the pixel-wise standard deviation (SD) of the T2* based on the fit residuals is proposed. For validation, a Monte-Carlo analysis was performed in which T2* phantoms were scanned N = 64 times, the true SD was measured and compared to the estimated SD. To improve accuracy and precision, the automatic truncation method for mitigating noise bias was extended to pixel-wise fitting by using an SNR scaled image reconstruction and truncating low SNR measurements. Finally, the precision and accuracy of non-linear regression with and without automatic truncation, were investigated using Monte-Carlo simulations.

Results

Measured and estimated SD’s were >99.9% correlated for non-linear regression with and without truncation. Non-linear regression with automatic truncation was shown to be the best mapping technique for improving accuracy and precision in low T2* and low SNR measurements.

Conclusions

A method for applying an automatic truncation method to pixel-wise T2* mapping that reduces T2* overestimation due to noise bias was proposed. A formulation for estimating pixel-wise standard deviation (SD) maps for T2* that can serve as a quality map for interpreting images and for comparison of imaging protocols was also proposed and validated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12968-015-0115-3) contains supplementary material, which is available to authorized users.     

Differentiation and stability of T helper 1 and 2 cells derived from naive human neonatal CD4+ T cells, analyzed at the single-cell level

The development of CD4+ T helper (Th) type 1 and 2 cells is essential for the eradication of pathogens, but can also be responsible for various pathological disorders. Therefore, modulation of Th cell differentiation may have clinical utility in the treatment of human disease. Here, we show that interleukin (IL) 12 and IL-4 directly induce human neonatal CD4- T cells, activated via CD3 and CD28, to differentiate into Th1 and Th2 subsets. In contrast, IL-13, which shares many biological activities with IL-4, failed to induce T cell differentiation, consistent with the observation that human T cells do not express IL-13 receptors. Both the IL-12-induced Th1 subset and the IL-4-induced Th2 subset produce large quantities of IL-10, confirming that human IL-10 is not a typical human Th2 cytokine. Interestingly, IL- 4-driven Th2 cell differentiation was completely prevented by an IL-4 mutant protein (IL-4.Y124D), indicating that this molecule acts as a strong IL-4 receptor antagonist. Analysis of single T cells producing interferon gamma or IL-4 revealed that induction of Th1 cell differentiation occurred rapidly and required only 4 d of priming of the neonatal CD4+ T cells in the presence of IL-12. The IL-12-induced Th1 cell phenotype was stable and was not significantly affected when repeatedly stimulated in the presence of recombinant IL-4. In contrast, the differentiation of Th2 cells occurred slowly and required not only 6 d of priming, but also additional restimulation of the primed CD4+ T cells in the presence of IL-4. Moreover, IL-4-induced Th2 cell phenotypes were not stable and could rapidly be reverted into a population predominantly containing Th0 and Th1 cells, after a single restimulation in the presence of IL-12. The observed differences in stability of IL-12- and IL-4-induced human Th1 and Th2 subsets, respectively, may have implications for cytokine-based therapies of chronic disease.     

T helper 1 and T helper 2 cells are pathogenic in an antigen-specific model of colitis.

Dysregulated T cell responses to enteric bacteria have been implicated as a common mechanism underlying pathogenesis in rodent models of colitis. However, the bacterial species and T cell specificities that induce disease have been poorly defined. We have developed a model system in which target antigen, bacterial host, and corresponding T cell specificity are defined. OVA-specific T cells from DO11.RAG-2(-/-) TCR transgenic mice were transferred into RAG-2(-/-) recipients whose intestinal tracts were colonized with OVA-expressing or control Escherichia coli. Transfer of antigen-naive DO11.RAG-2(-/-) T cells into recipients colonized with OVA-E. coli resulted in enhanced intestinal recruitment and cell cycling of OVA-specific T cells; however, there was no development of disease. In contrast, transfer of polarized T helper (Th) 1 and Th2 populations resulted in severe wasting and colitis in recipients colonized with OVA-expressing but not control E. coli. The histopathologic features of disease induced by Th1 and Th2 transfers were distinct, but disease severity was comparable. Induction of disease by both Th1 and Th2 transfers was dependent on bacterially associated OVA. These results establish that a single bacterially associated antigen can drive the progression of colitis mediated by both Th1 and Th2 cells and provide a new model for understanding the immunoregulatory interactions between T cells responsive to gut floral antigens.     

Oxidative stress parameters and keap 1 variants in T2DM: Association with T2DM,diabetic neuropathy,diabetic retinopathy,and obesity

IntroductionChronic hyperglycemia activates the inflammatory pathways and oxidative stress mechanisms with consequent damage to nerve tissue and retina. The Keap1‐Nrf2 pathway acts as one of the most important antioxidant pathways of the organism. Variants of Keap1 could affect susceptibility to diabetes and its complications.MethodsIn a case‐control study, 400 individuals included type 2 diabetes mellitus (T2DM) patients without complication, with neuropathy, with retinopathy, and healthy individuals were investigated. The levels of glutathione (GSH), glutathione peroxidase (GPx), malondialdehyde (MDA), and total antioxidant capacity (TAC) were measured using chemical methods. Using the PCR‐RFLP method, the Keap1 (rs11085735) variants were identified.ResultsNeuropathic patients had significantly lower levels of GSH, GPx, and TAC and higher levels of total oxidative status (TOS), MDA, and oxidative stress index (OSI) compared to T2DM patients without complication and controls. Lower levels of GSH and GPx and a higher level of MDA were observed in patients with retinopathy compared with controls. Obesity was associated with significantly lower GPx activity and higher TOS. A significantly higher Keap1 AA genotype was found in patients with neuropathy than T2DM without complication and controls. The presence of Keap1 AA genotype correlated with lower GPx activity compared to CC genotype.ConclusionsOur study suggests the role of reduced antioxidant system and Keap1 variants in the pathogenesis of T2DM and its complications of neuropathy and retinopathy and also obesity in enhanced oxidative stress. Monitoring oxidative stress parameters in diabetic patients, especially those with complication and their treatment with antioxidants is suggested.     

Assessment of activity levels for CYP2D6*1, CYP2D6*2, and CYP2D6*41 genes by population pharmacokinetics of dextromethorphan

The pharmacokinetics of dextromethorphan (DM) is markedly influenced by cytochrome P450 2D6 (CYP2D6) enzyme polymorphisms. The aim of this study was to quantify the effects of the CYP2D6*1, *2, and *41 variants on DM metabolism in vivo and to identify other sources of pharmacokinetic variability. Concentrations of DM and dextrorphan (DO) in plasma and urine were evaluated in 36 healthy Caucasian men. These volunteers participated in three clinical studies and received a single oral dose of 30?mg DM-HBr. Data were modeled simultaneously using the population pharmacokinetics NONMEM software. A five-compartment model adequately described the data. The activity levels of the alleles assessed differed significantly. The clearance attributable to an individual CYP2D6*1 copy was 2.5-fold higher as compared with CYP2D6*2 (5,010 vs. 2,020?l/h), whereas the metabolic activity of CYP2D6*41 was very low (85?l/h). Urinary pH was confirmed as a significant covariate for DM renal clearance. These results refine genotype-based predictions of pharmacokinetics for DM and presumably for other CYP2D6 substrates as well.     

Liver MR imaging: comparison of respiratory triggered fast spin echo with T2-weighted spin-echo and inversion recovery

Background: The purpose of this study was to compare a fast spin-echo sequence combined with a respiratory triggering device (R. trig. FSE) with conventional T2-weighted spin-echo (CSE) and inversion recovery (STIR) sequences for the detection of focal hepatic lesions. Methods: We performed a prospective study of 33 consecutive patients with known or suspected hepatic tumors. All patients underwent R. trig. FSE, CSE, and STIR imaging at 1.5 T. Acquisition times were 10.7 min for the CSE sequence and ranged from 12 to 15 min for STIR and from 5 to 7 min for R. trig FSE. For each sequence, liver–spleen contrast-to-noise ratio (CNR) and liver–lesion CNR were determined quantitatively. Image artifact and sharpness were graded by using a four-point scale on each sequence by two independent readers. Both readers also independently identified hepatic lesions (up to a maximum of eight per patient). For patients with focal lesions, the total number of lesions detected (on each sequence) and the minimum size of detected lesions were also determined by each reader. Results: No significant difference was detected between R. trig. FSE and CSE or STIR in either liver–spleen CNR or liver–lesion CNR. R. trig. FSE images were equivalent to CSE and superior to STIR in sharpness (p < 0.01) and presence of artifact (p < 0.01). R. trig. FSE detected a higher number of lesions (reader 1: n = 92, reader 2: n = 86) than CSE (reader 1: n = 70, reader 2: n = 69) and a significantly higher number than STIR (reader 1: n = 71, reader 2: n = 76). Lesion structure was significantly better defined with R. trig. FSE than with STIR (p < 0.01) and CSE (p < 0.05). Conclusions: Compared with CSE and STIR, R. trig. FSE produces hepatic images of comparable resolution and detects an increased number of focal hepatic lesions in a shorter period of time. Received: 5 April 1995/Accepted: 2 May 1995     

Type 1 T helper and type 2 T helper cells: Functions,regulation and role in protection and disease

Summary Two very distinct cytokine secretion patterns have been defined amoung murine CD4⁺ T cells. Type 1 helper (T_H1), but not type 2 helper (T_H2), cells produce interleukin (IL)-2, gamma-interferon (IFN-γ) and tumour necrosis factor-β, whereas T_H2, but not T_H1, cells express IL-4, IL-5, IL-6 and IL-10. The different cytokine patterns lead to different functions of the two types of T cell. In general, T_H2 cells are excellent helpers for B-cell antibody secretion, particularly IgE responses. On the other hand T_H1 cells induce delayed-type hypersensitivity reactions. There is general agreement that the different functional subsets of T_H cells arise post-thymically from a common pool of precursors and as a consequence of activation of antigen. However, the factors affecting differentiation of T_H precursors into the T_H1 or T_H2 subsets are still unclear. Mutual cross-regulation between T_H1 (via IFN-γ) and T_H2 (via IL-10) has also been reported. Recently, human T cell clones similar to murine T_H1 and T_H2 cells have been demonstrated. Most allergen- or helminthic antigen-specific CD4⁺ human T cell clones have a T_H2 phenotype, whereas the majority of T-cell clones specific for mycobacterial antigens or antigens responsible for type IV hypersensitivity exhibit a T_H1 phenotype. Human T_H2 clones provide B-cell help for IgE synthesis, whereas most T_H1 clones are cytolytic for antigen-presenting cells, including B lymphocytes. It is highly probable that the selective or preferential activation of CD4⁺ T-cell subsets secreting defined patterns of cytokines is of major importance in determining the class of immune effector function, thus influencing both protection and immunopathology.     

Association of UGT1A1*6, UGT1A1*28, or ABCC2 c.3972C>T genetic polymorphisms with irinotecan‐induced toxicity in Asian cancer patients: Meta‐analysis

Effects of UGT1A1*6 and UGT1A1*28 genetic polymorphisms on irinotecan‐induced severe toxicities in Asian cancer patients are inconclusive. Also, ABCC2 c.3972C>T may affect toxicity of irinotecan. The aim was to assess the aggregated risk of neutropenia or diarrhea in Asian cancer patients taking irinotecan and inherited UGT1A1*6, UGT1A1*28, or ABCC2 c.3972C>T genetic variants. A PubMed literature search for eligible studies was conducted. Odds ratios (ORs) were measured using RevMan software where p values <0.05 were statistically significant. Patients that inherited both UGT1A1*6 and UGT1A1*28 genetic variants (heterozygous: UGT1A1*1/*6 + *1/*28 and homozygous: UGT1A1*6/*6 + *28/*28) were significantly associated with increased risk of neutropenia and diarrhea compared to patients with UGT1A1*1/*1 (neutropenia: OR 2.89; 95% CI 1.97–4.23; p < 0.00001; diarrhea: OR 2.26; 95% CI 1.71–2.99; p < 0.00001). Patients carrying homozygous variants had much stronger effects in developing toxicities (neutropenia: OR 6.23; 95% CI 3.11–12.47; p < 0.00001; diarrhea: OR 3.21; 95% CI 2.13–4.85; p < 0.00001) than those with heterozygous variants. However, patients carrying the ABCC2 c.3972C>T genetic variant were not significantly associated with neutropenia (OR 1.67; 95% CI 0.98–2.84; p = 0.06) and were significantly associated with a reduction in irinotecan‐induced diarrhea (OR 0.31; 95% CI 0.11–0.81; p = 0.02). Asian cancer patients should undergo screening for both UGT1A1*6 and UGT1A1*28 genetic variants to reduce substantially irinotecan‐induced severe toxicities.

Study Highlights

• WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?

Cancer patients taking irinotecan and inheriting either UGT1A1*6 or UGT1A1*28 genetic polymorphisms or a combination of these variants (UGT1A1*6 + UGT1A1*28) are associated with severe toxicities such as neutropenia or diarrhea, but the aggregated risk is highly inconsistent, especially in Asian cancer patients. Also, the ABCC2 c.3972C>T genetic polymorphism is associated with irinotecan‐induced toxicities.

• WHAT QUESTION DID THIS STUDY ADDRESS?

Is the combination of UGT1A1*6 and UGT1A1*28 genetic polymorphisms or ABCC2 c.3972C>T genetic variant associated with severe neutropenia or diarrhea in Asian cancer patients?

• WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?

Asian cancer patients, irrespective of the type of cancer, who carried both the UGT1A1*6 and UGT1A1*28 genetic variants were significantly associated with increased risk of neutropenia and diarrhea compared to patients with UGT1A1*1/*1, and the effects were even more striking in cancer patients with homozygous variants than those with heterozygous variants. In addition, dose‐dependent analysis indicated that a high dose of irinotecan (>150 mg/m²) was significantly associated with diarrhea in cancer patients that carried both the UGT1A1*6 and UGT1A1*28 genetic variants compared to patients on medium and low doses of irinotecan. However, patients carrying the ABCC2 c.3972C>T genetic variant were not significantly associated with irinotecan‐induced toxicities.

• HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?

The results presented in this meta‐analysis will greatly enhance the clinical practice of irinotecan therapy considering UGT1A1*6 and UGT1A1*28 pharmacogenetics. The findings of this study will also assist clinicians in suggesting genotyping for UGT1A1*6 and UGT1A1*28 polymorphisms prior to administering irinotecan therapy as part of standard care and may advance the translation of irinotecan pharmacogenetics to the bedside.     

Hindered diffusion of MRI contrast agents in rat brain extracellular micro‐environment assessed by acquisition of dynamic T1 and T2 maps

The knowledge of brain tissues characteristics (such as extracellular space and tortuosity) represents valuable information for the design of optimal MR probes for specific biomarkers targeting. This work proposes a methodology based on dynamic acquisition of relaxation time maps to quantify in vivo MRI contrast agent concentration after intra‐cerebral injection in rat brain. It was applied to estimate the hindered diffusion in brain tissues of five contrast agents with different hydrodynamic diameters (Dotarem® ≈ 1 nm, P846 ≈ 4 nm, P792 ≈ 7 nm, P904 ≈ 22 nm and Gd‐based emulsion ≈ 170 nm). In vivo apparent diffusion coefficients were compared with those estimated in an obstacle‐free medium to determine brain extracellular space and tortuosity. At a 2 h imaging timescale, all contrast agents except the Gd‐based emulsion exhibited significant diffusion through brain tissues, with characteristic times compatible with MR molecular imaging (<70 min to diffuse between two capillaries). In conclusion, our experiments indicate that MRI contrast agents with sizes up to 22 nm can be used to perform molecular imaging on intra‐cerebral biomarkers. Our quantification methodology allows a precise estimation of apparent diffusion coefficients, which is helpful to calibrate optimal timing between contrast agent injection and MRI observation for molecular imaging studies. Copyright © 2012 John Wiley & Sons, Ltd.     

Type 1 T helper and type 2 T helper cells: functions, regulation and role in protection and disease.

Two very distinct cytokine secretion patterns have been defined among murine CD4+ T cells. Type 1 helper (TH1), but not type 2 helper (TH2), cells produce interleukin (IL)-2, gamma-interferon (IFN-gamma) and tumour necrosis factor-beta, whereas TH2, but not TH1, cells express IL-4, IL-5, IL-6 and IL-10. The different cytokine patterns lead to different functions of the two types of T cell. In general, TH2 cells are excellent helpers for B-cell antibody secretion, particularly IgE responses. On the other hand TH1 cells induce delayed-type hypersensitivity reactions. There is general agreement that the different functional subsets of TH cells arise post-thymically from a common pool of precursors and as a consequence of activation of antigen. However, the factors affecting differentiation of TH precursors into the TH1 or TH2 subsets are still unclear. Mutual cross-regulation between TH1 (via IFN-gamma) and TH2 (via IL-10) has also been reported. Recently, human T cell clones similar to murine TH1 and TH2 cells have been demonstrated. Most allergen- or helminthic antigen-specific CD4+ human T cell clones have a TH2 phenotype, whereas the majority of T-cell clones specific for mycobacterial antigens or antigens responsible for type IV hypersensitivity exhibit a TH1 phenotype. Human TH2 clones provide B-cell help for IgE synthesis, whereas most TH1 clones are cytolytic for antigen-presenting cells, including B lymphocytes. It is highly probable that the selective or preferential activation of CD4+ T-cell subsets secreting defined patterns of cytokines is of major importance in determining the class of immune effector function, thus influencing both protection and immunopathology.     

慢性乙型肝炎、乙型肝炎肝硬化与HLA—DRB1＊0701、DRB1＊1301—2等位基因的关联性

目的探讨乙型肝炎肝硬化与HLA—DRB1＊0701、DRB1＊1301—2等位基因的关联性。方法采用聚合酶链反应一序列特应性引物（PCRSSP）方法以健康人（39例）作对照,对吉林地区汉族32例慢性乙型肝炎患者和26例乙型肝炎肝硬化患者HI,ADRB1＊0701、DRB1＊13012等位基因进行了检测。结果慢性乙型肝炎组和乙型肝炎肝硬化组分别与健康对照组比较,发现慢性乙型肝炎组和乙型肝炎肝硬化组HLA-DRB1＊0701等位基因频率明显高于健康对照组（10．9％vs1．3％,13．5％vs1．3％,P〈0．05）,DRB1＊1301-2等位基因频率在3组间的差异无统计学意义（P〉0．05）。结论HLA—DRB1＊0701等位基因与吉林地区汉族人与慢性乙型肝炎和乙型肝炎肝硬化相关,可能是慢性乙型肝炎、乙型肝炎肝硬化的易感基因。     

MR imaging of cervical carcinoma: comparison among T2-weighted,dynamic, and postcontrast T1-weighted images with histopathological correlation

Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images. Received: 10 November 1995/Accepted after revision: 13 March 1996     

Combined measurement of perfusion,venous oxygen saturation,and skeletal muscle T2* during reactive hyperemia in the leg

Background

The function of the peripheral microvascular may be interrogated by measuring perfusion, tissue oxygen concentration, or venous oxygen saturation (SvO₂) recovery dynamics following induced ischemia. The purpose of this work is to develop and evaluate a magnetic resonance (MR) technique for simultaneous measurement of perfusion, SvO₂, and skeletal muscle T₂*.

Methods

Perfusion, Intravascular Venous Oxygen saturation, and T₂* (PIVOT) is comprised of interleaved pulsed arterial spin labeling (PASL) and multi-echo gradient-recalled echo (GRE) sequences. During the PASL post-labeling delay, images are acquired with a multi-echo GRE to quantify SvO₂ and T₂* at a downstream slice location. Thus time-courses of perfusion, SvO₂, and T₂* are quantified simultaneously within a single scan. The new sequence was compared to separately measured PASL or multi-echo GRE data during reactive hyperemia in five young healthy subjects. To explore the impairment present in peripheral artery disease patients, five patients were evaluated with PIVOT.

Results

Comparison of PIVOT-derived data to the standard techniques shows that there was no significant bias in any of the time-course-derived metrics. Preliminary data show that PAD patients exhibited alterations in perfusion, SvO₂, and T₂* time-courses compared to young healthy subjects.

Conclusion

Simultaneous quantification of perfusion, SvO₂, and T₂* is possible with PIVOT. Kinetics of perfusion, SvO₂, and T₂* during reactive hyperemia may help to provide insight into the function of the peripheral microvasculature in patients with PAD.