磁共振波谱成像评价绝经前双侧卵巢切除术对骨髓脂肪的影响

目的探讨磁共振波谱成像(MRS)评估绝经前双侧卵巢切除术对腰椎骨髓脂肪的影响。方法收集32例接受子宫切除术和双侧卵巢切除术的患者(年龄47.4±2.8岁),分别在术前、术后第6个月、12个月行腰3椎体MRS扫描,测定骨髓脂肪分数(fat fraction,FF)。同时,定量CT测量L 3椎体松质骨容积骨密度(vBMD)。结果卵巢切除术后,腰椎vBMD呈现时序性降低而骨髓FF呈现急剧时序性增高。术后6个月骨髓FF及腰椎vBMD分别为(49.7±6.9)%、(134±22)mg/cc,FF急剧增加22.7%,而vBMD下降9.5%。术后12个月时骨髓FF及腰椎vBMD分别为(53.1±6.3)%、(128±24)mg/cc,分别较6个月时增高6.8%、降低4.5%。相关性分析示△vBMD6M-0M与△FF6M-0M(r=-0.801,P<0.001)、△vBMD12M-0M与△FF12M-0M(r=-0.769,P<0.001)以及△vBMD12M-6M与△FF12M-6M(r=-0.680,P<0.001)均存在负相关性。结论双侧卵巢切除术导致骨髓脂肪含量急剧增加,骨小梁密度减少。MRS测定卵巢切除术后骨髓脂肪或许可早于BMD探及骨髓分子生化成分变化。     

Use of Quantitative Vertebral Bone Marrow Fat Fraction to Assess Disease Activity and Chronicity in Patients with Ankylosing Spondylitis

ObjectiveWe quantitatively measured the fat fraction (FF) in the vertebrae of patients with ankylosing spondylitis (AS) using magnetic resonance imaging (MRI) and investigated the role of FF as an indicator of both active inflammation and chronicity.Materials and MethodsA total of 52 patients with AS who underwent spinal MRI were retrospectively evaluated. The FF values of the anterosuperior and anteroinferior corners of the bone marrow in the L1-S1 spine were assessed using the modified Dixon technique. AS activity was measured using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), AS Disease Activity Score (ASDAS), and serum inflammatory marker levels. AS disease chronicity was assessed by AS disease duration and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Univariable and multivariable regression analyses were conducted to investigate the correlation between FF and other clinical characteristics.ResultsThe mean FF ± standard deviation of the total lumbar spine was 43.0% ± 11.3%. At univariable analysis, spinal FF showed significant negative correlation with BASDAI (β = −0.474, p = 0.002) and ASDAS with C-reactive protein (ASDAS-CRP; β = −0.478, p = 0.002) and a significant positive correlation with AS disease duration (β = 0.440, p = 0.001). After adjusting for patient age, sex, and total mSASSS score, spinal FF remained significantly negatively correlated with BASDAI (β = −0.543, p < 0.001), ASDAS-CRP (β = −0.568, p < 0.001), and ASDAS with erythrocyte sedimentation rate (β = −0.533, p = 0.001). Spinal FF was significantly lower in patients with very high disease activity (ASDAS-CRP > 3.5) than in those with only high disease activity (2.1 ≤ ASDAS-CRP ≤ 3.5) (p = 0.010).ConclusionSpinal FF may help assess both AS disease activity and chronicity.     

Peritumoral Fat Content Correlates with Histological Prognostic Factors in Breast Carcinoma: A Study Using Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-squares Estimation (IDEAL)

Purpose:To correlate peritumoral fat content using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with histologic prognostic factors in breast carcinoma.Methods:This study consisted of 100 patients who were diagnosed with invasive carcinoma of breast and underwent breast MRI including IDEAL before surgery. The scan time of IDEAL fat fraction (FF) map imaging was 33 s. Four regions of interests (ROIs), which are a distance of 5 mm from the tumor edge, and one ROI in the mammary fat of the healthy side were set on the FF map. Then average peritumoral FF values (FFt), average FF values in the healthy side (FFh), and peritumoral fat ratio (pTFR: defined as FFt/FFh) were calculated. Histologically, the presence of lymph node metastasis and the MIB-1 index were evaluated.Results:FFt and pTFR for breast carcinoma with lymph node metastasis (79.27 ± 10.36 and 0.897 ± 0.078) were significantly lower than those without (86.23 ± 4.53 and 0.945 ± 0.032) (P < 0.001 and P = 0.005). Spearman rank correlation suggested that the FFt correlated with the MIB-1 index (r = −340, P = 0.001).Conclusion:Quantification of peritumoral fat using IDEAL-iron quantification is associated with the histologic prognostic factors, and may be a practical tool for therapeutic strategy of breast carcinoma.     

~1H MRS对椎体骨髓研究初步应用

目的 探讨椎体骨髓脂肪含量(fat fraction,FF)在不同年龄组、性别的变化规律及与骨密度(bone mineral densities,BMD)的相关性.方法 对85名年龄21～70岁健康志愿者及20名已行腰椎双能量X线吸收测定(dual X-ray absorptionmetry,DXA)诊断为骨质疏松的老年男女进行前瞻性MR波谱分析,测定L_3椎体脂肪分数值(fat fraction,FF).健康志愿者按每10岁为一个年龄段,将其分为5组,每组16～18人.结果 21～30岁组、31～40岁组、41～50岁组、51～60岁组、>60岁组和骨质疏松组的FF分别为30.7%±4.4%、35.5%±6.8%、41.9%士6.6%、46.8%±5.5%、51.7%±5.2%和59.2%±7.4%;除>60岁组和骨质疏松组外,各组L_3椎体脂肪含量男性均比女性高(P<0.05),其中,41～50岁组中的男女差别最大,达11.1%.骨质疏松组FF与BMD呈负相关关系(γ=-0.6,P<0.01).结论 正常椎体骨髓脂肪含量随年龄而逐渐增加,~1H MRS可作为评价骨质量的新手段.     

动态增强MRI评价去势兔骨质疏松腰椎骨髓灌注:与BMD和MVD对照研究

目的用MR动态增强观察去势兔骨质疏松腰椎的骨髓灌注变化,并与骨密度(BMD)、免疫组织化学对照。材料与方法新西兰大白兔22只,随机分为2组(实验组12只,对照组10只)。双侧卵巢切除术后3、5、7个月分别行动态增强MRI和双能X线吸收测量法(DEXA)检测腰椎骨髓灌注的最大增强百分比(Emax)、增强斜率(ES)和BMD,并与组织的微血管密度(MVD)对照。结果双侧卵巢切除去势法(OVX)组兔在术后7个月时腰椎BMD与对照组相比明显降低(P<0.05)。术后3个月和5个月两组间腰椎的Emax和ES值均无明显差异(P>0.05);术后第7个月OVX组腰椎的灌注较对照组明显下降,Emax和ES值均明显降低(P<0.05);对照组腰椎骨髓MVD计数平均为67.58±11.6;而OVX组的MVD计数为39.32±9.54,明显少于对照组(P<0.05)。OVX组兔术后7个月腰椎动态增强MRI的Emax、ES和组织的MVD呈正相关(r分别为0.866和0.771,P<0.05);Emax、ES和腰椎BMD之间亦有明显的正相关性(r分别为0.714和0.820,P<0.05)。结论去势兔骨质疏松后腰椎骨髓的血液灌注明显下...     

Hydrocephalus: Ventricular Volume Quantification Using Three-Dimensional Brain CT Data and Semiautomatic Three-Dimensional Threshold-Based Segmentation Approach

ObjectiveTo evaluate the usefulness of the ventricular volume percentage quantified using three-dimensional (3D) brain computed tomography (CT) data for interpreting serial changes in hydrocephalus.Materials and MethodsIntracranial and ventricular volumes were quantified using the semiautomatic 3D threshold-based segmentation approach for 113 brain CT examinations (age at brain CT examination ≤ 18 years) in 38 patients with hydrocephalus. Changes in ventricular volume percentage were calculated using 75 serial brain CT pairs (time interval 173.6 ± 234.9 days) and compared with the conventional assessment of changes in hydrocephalus (increased, unchanged, or decreased). A cut-off value for the diagnosis of no change in hydrocephalus was calculated using receiver operating characteristic curve analysis. The reproducibility of the volumetric measurements was assessed using the intraclass correlation coefficient on a subset of 20 brain CT examinations.ResultsMean intracranial volume, ventricular volume, and ventricular volume percentage were 1284.6 ± 297.1 cm³, 249.0 ± 150.8 cm³, and 19.9 ± 12.8%, respectively. The volumetric measurements were highly reproducible (intraclass correlation coefficient = 1.0). Serial changes (0.8 ± 0.6%) in ventricular volume percentage in the unchanged group (n = 28) were significantly smaller than those in the increased and decreased groups (6.8 ± 4.3% and 5.6 ± 4.2%, respectively; p = 0.001 and p < 0.001, respectively; n = 11 and n = 36, respectively). The ventricular volume percentage was an excellent parameter for evaluating the degree of hydrocephalus (area under the receiver operating characteristic curve = 0.975; 95% confidence interval, 0.948–1.000; p < 0.001). With a cut-off value of 2.4%, the diagnosis of unchanged hydrocephalus could be made with 83.0% sensitivity and 100.0% specificity.ConclusionThe ventricular volume percentage quantified using 3D brain CT data is useful for interpreting serial changes in hydrocephalus.     

Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Pancreas: Comparison with Conventional Single-Shot Echo-Planar Imaging

ObjectiveTo investigate the image quality (IQ) and apparent diffusion coefficient (ADC) of reduced field-of-view (FOV) di-ffusion-weighted imaging (DWI) of pancreas in comparison with full FOV DWI.ResultsOn qualitative analysis, reduced FOV DWI showed better anatomic structure visualization (2.76 ± 0.79 at b = 0 s/mm² and 2.81 ± 0.64 at b = 400 s/mm²), lesion conspicuity (3.11 ± 0.99 at b = 0 s/mm² and 3.15 ± 0.79 at b = 400 s/mm²), IQ score (8.51 ± 2.05 at b = 0 s/mm² and 8.79 ± 1.60 at b = 400 s/mm²), and higher clinical utility (3.41 ± 0.64), as compared to full FOV DWI (anatomic structure, 2.18 ± 0.59 at b = 0 s/mm² and 2.56 ± 0.47 at b = 500 s/mm²; lesion conspicuity, 2.55 ± 1.07 at b = 0 s/mm² and 2.89 ± 0.86 at b = 500 s/mm²; IQ score, 7.13 ± 1.83 at b = 0 s/mm² and 8.17 ± 1.31 at b = 500 s/mm²; clinical utility, 3.14 ± 0.70) (p < 0.05). Artifacts were significantly improved on reduced FOV DWI (2.65 ± 0.68) at b = 0 s/mm² (full FOV DWI, 2.41 ± 0.63) (p < 0.001). On quantitative analysis, there were no significant differences between the 2 DWI sequences in ADCs of various pancreatic lesions and parenchyma (p > 0.05). ADCs of adenocarcinomas (1.061 × 10^-3 mm²/s ± 0.133 at reduced FOV and 1.079 × 10^-3 mm²/s ± 0.135 at full FOV) and neuroendocrine tumors (0.983 × 10^-3 mm²/s ± 0.152 at reduced FOV and 1.004 × 10^-3 mm²/s ± 0.153 at full FOV) were significantly lower than those of parenchyma (1.191 × 10^-3 mm²/s ± 0.125 at reduced FOV and 1.218 × 10^-3 mm²/s ± 0.103 at full FOV) (p < 0.05).ConclusionReduced FOV DWI of the pancreas provides better overall IQ including better anatomic detail, lesion conspicuity and subjective clinical utility.     

双能量CT虚拟去钙技术评价骨质疏松症的价值

目的 评估双能量CT（DECT）虚拟去钙（VNCa）技术定量评价骨质疏松症的应用价值。 方法 回顾性纳入55例慢性腰腿痛病人,其中男29例,女26例,平均年龄（49.8±12.1）岁。所有病人均行腰椎DECT扫描并采集定量CT（QCT）数据。通过修改双能量分析软件中虚拟平扫的配置文件,定量测量对比剂CT值（CM）、常规CT值（rCT）、钙浓度（CaD）及脂肪分数（FF）;利用QCT pro定量分析系统测量椎体的骨密度（BMD）。依据金标准BMD< 80 mg/cm³,将纳入的全部椎体（318个）分为骨质疏松组（OP,87个）和非骨质疏松组（NOP,231个）。采用组内相关系数（ICC）分析2名医师测量数据结果的一致性。采用独立样本t检验比较2组间DECT定量参数的差异。采用Pearson相关分析BMD与DECT定量参数的相关性,并建立多元线性回归模型,将由该模型计算得到的BMD表示为回归BMD（rBMD）,得出决定系数r²和rBMD的方程。以QCT的BMD值作为金标准,采用受试者操作特征（ROC）曲线评价rBMD、CM、CaD、FF的诊断效能。 结果 2名医生测量BMD和DECT定量参数的一致性较好（均ICC>0.75）。OP组的CM、rCT、CaD均低于NOP组,而FF高于NOP组（均P<0.05）。CM、rCT、CaD、FF值与BMD均具有相关性（r分别为0.885、0.947、0.877、-0.492,均P<0.05）。将CM、CaD、FF纳入回归模型计算得出:r²=0.915,rBMD=54.82-0.19×CM+20.03×CaD-1.24×FF。当rBMD的阈值为81.94 mg/cm³时诊断效能最高,其敏感度、特异度、AUC分别为90.04%、91.95%、0.966（0.940~0.983）。 结论 DECT的VNCa技术可作为一种BMD测量的补充方法,从骨矿物质及脂肪含量方面定量评价骨质疏松症。     

Monitoring Cerebral Perfusion Changes Using Arterial Spin-Labeling Perfusion MRI after Indirect Revascularization in Children with Moyamoya Disease

ObjectiveTo assess the role of arterial spin-labeling (ASL) perfusion MRI in identifying cerebral perfusion changes after indirect revascularization in children with moyamoya disease.Materials and MethodsWe included pre- and postoperative perfusion MRI data of 30 children with moyamoya disease (13 boys and 17 girls; mean age ± standard deviation, 6.3 ± 3.0 years) who underwent indirect revascularization between June 2016 and August 2017. Relative cerebral blood flow (rCBF) and qualitative perfusion scores for arterial transit time (ATT) effects were evaluated in the middle cerebral artery (MCA) territory on ASL perfusion MRI. The rCBF and relative time-to-peak (rTTP) values were also measured using dynamic susceptibility contrast (DSC) perfusion MRI. Each perfusion change on ASL and DSC perfusion MRI was analyzed using the paired t test. We analyzed the correlation between perfusion changes on ASL and DSC images using Spearman''s correlation coefficient.ResultsThe ASL rCBF values improved at both the ganglionic and supraganglionic levels of the MCA territory after surgery (p = 0.040 and p = 0.003, respectively). The ATT perfusion scores also improved at both levels (p < 0.001 and p < 0.001, respectively). The rCBF and rTTP values on DSC MRI showed significant improvement at both levels of the MCA territory of the operated side (all p < 0.05). There was no significant correlation between the improvements in rCBF values on the two perfusion images (r = 0.195, p = 0.303); however, there was a correlation between the change in perfusion scores on ASL and rTTP on DSC MRI (r = 0.701, p < 0.001).ConclusionRecognizing the effects of ATT on ASL perfusion MRI may help monitor cerebral perfusion changes and complement quantitative rCBF assessment using ASL perfusion MRI in patients with moyamoya disease after indirect revascularization.     

Quantitative Analysis of Microperfusion in Contrast-Induced Nephropathy Using Contrast-Enhanced Ultrasound: An Animal Study

ObjectiveTo investigate imaging biomarkers of microperfusion in contrast-induced nephropathy (CIN) using contrast-enhanced ultrasound (CEUS).Materials and MethodsThe CIN model was fabricated by administering indomethacin (10 mg/kg), L-NAME (15 mg/kg), and iopamidol (10 mL/kg) to Sprague-Dawley rats. After 24 hours, CEUS was performed on CIN (n = 6) and control (n = 6) rats with sulphur hexafluoride microbubbles (SonoVue). From time-intensity curves obtained from the kidney arriving time (AT), acceleration time (AC), time to peak (TTP), and peak enhancement (PE) were measured and compared between the groups. After CEUS, the rats were sacrificed, and cell apoptosis markers were evaluated to confirm the development of CIN.ResultsAmong CEUS parameters, AT (7.8 ± 1.6 vs. 4.2 ± 0.5 s, p = 0.002), AC (4.7 ± 1.4 vs. 2.0 ± 0.4 s, p = 0.002), and TTP (12.5 ± 2.9 vs. 6.2 ± 0.6 s, p = 0.002) were significantly prolonged in the CIN group compared to controls. PE was significantly higher in the control group than in the CIN group (17.1 ± 1.9 vs. 12.2 ± 2.0 dB, p = 0.004). In kidney tissue, mRNA and protein levels of the apoptotic makers were significantly higher in the CIN group than in the control group (p = 0.003 and p = 0.002).ConclusionCEUS parameters can be used as imaging biomarkers for microperfusion in CIN. In rats with CIN, AT, AC, and TTP were significantly prolonged, while PE was significantly lower compared to controls.     

Free-Breathing Motion-Corrected Single-Shot Phase-Sensitive Inversion Recovery Late-Gadolinium-Enhancement Imaging: A Prospective Study of Image Quality in Patients with Hypertrophic Cardiomyopathy

ObjectiveMotion-corrected averaging with a single-shot technique was introduced for faster acquisition of late-gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging while free-breathing. We aimed to evaluate the image quality (IQ) of free-breathing motion-corrected single-shot LGE (moco-ss-LGE) in patients with hypertrophic cardiomyopathy (HCM).Materials and MethodsBetween April and December 2019, 30 patients (23 men; median age, 48.5; interquartile range [IQR], 36.5–61.3) with HCM were prospectively enrolled. Breath-held single-shot LGE (bh-ss-LGE) and free-breathing moco-ss-LGE images were acquired in random order on a 3T MR system. Semi-quantitative IQ scores, contrast-to-noise ratios (CNRs), and quantitative size of myocardial scar were assessed on pairs of bh-ss-LGE and moco-ss-LGE. The mean ± standard deviation of the parameters was obtained. The results were compared using the Wilcoxon signed-rank test.ResultsThe moco-ss-LGE images had better IQ scores than the bh-ss-LGE images (4.55 ± 0.55 vs. 3.68 ± 0.45, p < 0.001). The CNR of the scar to the remote myocardium (34.46 ± 11.85 vs. 26.13 ± 10.04, p < 0.001), scar to left ventricle (LV) cavity (13.09 ± 7.95 vs. 9.84 ± 6.65, p = 0.030), and LV cavity to remote myocardium (33.12 ± 15.53 vs. 22.69 ± 11.27, p < 0.001) were consistently greater for moco-ss-LGE images than for bh-ss-LGE images. Measurements of scar size did not differ significantly between LGE pairs using the following three different quantification methods: 1) full width at half-maximum method; 23.84 ± 12.88% vs. 24.05 ± 12.81% (p = 0.820), 2) 6-standard deviation method, 15.14 ± 10.78% vs. 15.99 ± 10.99% (p = 0.186), and 3) 3-standard deviation method; 36.51 ± 17.60% vs. 37.50 ± 17.90% (p = 0.785).ConclusionMotion-corrected averaging may allow for superior IQ and CNRs with free-breathing in single-shot LGE imaging, with a herald of free-breathing moco-ss-LGE as the scar imaging technique of choice for clinical practice.     

Radiofrequency versus Ethanol Ablation for Treating Predominantly Cystic Thyroid Nodules: A Randomized Clinical Trial

ObjectiveTo compare single-session radiofrequency ablation (RFA) and ethanol ablation (EA) for treating predominantly cystic thyroid nodules (PCTNs).ResultsThe mean volume reduction was 87.5 ± 11.5% for RFA (n = 22) and 82.4 ± 28.6% for EA (n = 24) (p = 0.710; mean difference [95% confidence interval], 5.1% [-8.0 to 18.2]), indicating no significant difference. Regarding the secondary outcomes, therapeutic success (p = 0.490), mean symptom (p = 0.205) and cosmetic scores (p = 0.710) showed no difference. There were no major complications in either group (p > 0.99).ConclusionThe therapeutic efficacy of RFA is not superior to that of EA; therefore, EA might be preferable as the first-line treatment for PCTNs.     

Serial Observations of Muscle and Fat Mass as Prognostic Factors for Deceased Donor Liver Transplantation

ObjectiveMuscle depletion in patients undergoing liver transplantation affects the recipients'' prognosis and therefore cannot be overlooked. We aimed to evaluate whether changes in muscle and fat mass during the preoperative period are associated with prognosis after deceased donor liver transplantation (DDLT).Materials and MethodsThis study included 72 patients who underwent DDLT and serial computed tomography (CT) scans. Skeletal muscle index (SMI) and fat mass index (FMI) were calculated using the muscle and fat area in CT performed 1 year prior to surgery (1 yr Pre-LT), just before surgery (Pre-LT), and after transplantation (Post-LT). Simple aspects of serial changes in muscle and fat mass were analyzed during three measurement time points. The rate of preoperative changes in body composition parameters were calculated (preoperative ΔSMI [%] = [SMI at Pre-LT − SMI at 1 yr Pre-LT] / SMI at Pre-LT × 100; preoperative ΔFMI [%] = [FMI at Pre-LT − FMI at 1 yr Pre-LT] / FMI at Pre-LT × 100) and assessed for correlation with patient survival.ResultsSMI significantly decreased during the preoperative period (mean preoperative ΔSMI, −13.04%, p < 0.001). In the multivariable analysis, preoperative ΔSMI (p = 0.016) and model for end-stage liver disease score (p = 0.011) were independent prognostic factors for overall survival. The mean survival time for patients with a threshold decrease in the preoperative ΔSMI (≤ −30%) was significantly shorter than for other patients (p = 0.007). Preoperative ΔFMI was not a prognostic factor but FMI increased during the postoperative period (p = 0.009) in all patients.ConclusionA large reduction in preoperative SMI was significantly associated with reduced survival after DDLT. Therefore, changes in muscle mass during the preoperative period can be considered as a prognostic factor for survival after DDLT.     

A study of using a deep learning image reconstruction to improve the image quality of extremely low-dose contrast-enhanced abdominal CT for patients with hepatic lesions

Objective:To investigate the feasibility of using deep learning image reconstruction (DLIR) to significantly reduce radiation dose and improve image quality in contrast-enhanced abdominal CT.Methods:This was a prospective study. 40 patients with hepatic lesions underwent abdominal CT using routine dose (120kV, noise index (NI) setting of 11 with automatic tube current modulation) in the arterial-phase (AP) and portal-phase (PP), and low dose (NI = 24) in the delayed-phase (DP). All images were reconstructed at 1.25 mm thickness using ASIR-V at 50% strength. In addition, images in DP were reconstructed using DLIR in high setting (DLIR-H). The CT value and standard deviation (SD) of hepatic parenchyma, spleen, paraspinal muscle and lesion were measured. The overall image quality includes subjective noise, sharpness, artifacts and diagnostic confidence were assessed by two radiologists blindly using a 5-point scale (1, unacceptable and 5, excellent). Dose between AP and DP was compared, and image quality among different reconstructions were compared using SPSS20.0.Results:Compared to AP, DP significantly reduced radiation dose by 76% (0.76 ± 0.09 mSv vs 3.18 ± 0.48 mSv), DLIR-H DP images had lower image noise (14.08 ± 2.89 HU vs 16.67 ± 3.74 HU, p < 0.001) but similar overall image quality score as the ASIR-V50% AP images (3.88 ± 0.34 vs 4.05 ± 0.44, p > 0.05). For the DP images, DLIR-H significantly reduced image noise in hepatic parenchyma, spleen, muscle and lesion to (14.77 ± 2.61 HU, 14.26 ± 2.67 HU, 14.08 ± 2.89 HU and 16.25 ± 4.42 HU) from (24.95 ± 4.32 HU, 25.42 ± 4.99 HU, 23.99 ± 5.26 HU and 27.01 ± 7.11) with ASIR-V50%, respectively (all p < 0.001) and improved image quality score (3.88 ± 0.34 vs 2.87 ± 0.53; p < 0.05).Conclusion:DLIR-H significantly reduces image noise and generates images with clinically acceptable quality and diagnostic confidence with 76% dose reduction.Advances in knowledge:(1) DLIR-H yielded a significantly lower image noise, higher CNR and higher overall image quality score and diagnostic confidence than the ASIR-V50% under low signal conditions. (2) Our study demonstrated that at 76% lower radiation dose, the DLIR-H DP images had similar overall image quality to the routine-dose ASIR-V50% AP images.     

Apparent diffusion coefficient and fractional anisotropy in the vertebral bone marrow

Purpose:

To assess the state of cancellous tissue we analyzed the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in vertebral bone marrow.

Materials and Methods:

With 1.5 T magnetic resonance imaging (MRI), single‐shot diffusion echo planar imaging was used with b factors of 0 and 1000 s/mm², diffusion‐sensitizing gradient in six directions, sensitivity encoding technique, effective TE of 74 msec, and TR of 1800 msec. ADC and FA were determined in the lumbar vertebral body of 11 normal subjects (age 31 632–635 years), and then compared with the bone mineral density (BMD) obtained with dual‐energy x‐ray absorptiometry (DXA). Moreover, fat fraction (FF) of the bone marrow was measured with spectral presaturation with inversion recovery (SPIR) in the same subject.

Results:

A strong negative correlation was found between ADC and BMD for low or moderate FF in vertebral bone marrow. Moreover, a significant positive correlation was noted between ADC and FF in this region. There was a positive correlation between FA and BMD, and no correlation between FA and FF in the vertebral bone marrow.

Conclusion:

Diffusion analyses with ADC and FA make it possible to obtain more detailed information on the structure of cancellous tissue and bone metabolism. J. Magn. Reson. Imaging 2010;31:632–635. © 2010 Wiley‐Liss, Inc.     

Ultrasound-Guided Delivery of siRNA and a Chemotherapeutic Drug by Using Microbubble Complexes: In Vitro and In Vivo Evaluations in a Prostate Cancer Model

ObjectiveTo evaluate the effectiveness of ultrasound and microbubble-liposome complex (MLC)-mediated delivery of siRNA and doxorubicin into prostate cancer cells and its therapeutic capabilities both in vitro and in vivo.ResultsConfocal microscopy demonstrated substantial intracellular uptake of MLCs in LNCaP, which expresses higher levels of Her2 than PC-3. The viability of LNCaP cells was significantly reduced after the delivery of MLCs loaded with siRNA and doxorubicin (85.0 ± 2.9%), which was further potentiated by application of ultrasound (55.0 ± 3.5%, p = 0.009). Survivin expression was suppressed in vivo in LNCaP tumor xenograft model following the ultrasound and MLC-guided delivery of siRNA (77.4 ± 4.90% to 36.7 ± 1.34%, p = 0.027).ConclusionMicrobubble-liposome complex can effectively target prostate cancer cells, enabling intracellular delivery of the treatment agents with the use of ultrasound. Ultrasound and MLC-mediated delivery of survivin-targeted siRNA and doxorubicin can induce prostate cell apoptosis and block survivin expression in vitro and in vivo.     

Cerebral Perfusion Pressure is Maintained in Acute Intracerebral Hemorrhage: A CT Perfusion Study

BACKGROUND AND PURPOSE:Although blood pressure reduction has been postulated to result in a fall in cerebral perfusion pressure in patients with intracerebral hemorrhage, the latter is rarely measured. We assessed regional cerebral perfusion pressure in patients with intracerebral hemorrhage by using CT perfusion source data.MATERIALS AND METHODS:Patients with acute primary intracerebral hemorrhage were randomized to target systolic blood pressures of <150 mm Hg (n = 37) or <180 mm Hg (n = 36). Regional maps of cerebral blood flow, cerebral perfusion pressure, and cerebrovascular resistance were generated by using CT perfusion source data, obtained 2 hours after randomization.RESULTS:Perihematoma cerebral blood flow (38.7 ± 11.9 mL/100 g/min) was reduced relative to contralateral regions (44.1 ± 11.1 mL/100 g/min, P = .001), but cerebral perfusion pressure was not (14.4 ± 4.6 minutes⁻¹ versus 14.3 ± 4.8 minutes⁻¹, P = .93). Perihematoma cerebrovascular resistance (0.34 ± 0.11 g/mL) was higher than that in the contralateral region (0.30 ± 0.10 g/mL, P < .001). Ipsilateral and contralateral cerebral perfusion pressure in the external (15.0 ± 4.6 versus 15.6 ± 5.3 minutes⁻¹, P = .15) and internal (15.0 ± 4.8 versus 15.0 ± 4.8 minutes⁻¹, P = .90) borderzone regions were all similar. Borderzone cerebral perfusion pressure was similar to mean global cerebral perfusion pressure (14.7 ± 4.7 minutes⁻¹, P ≥ .29). Perihematoma cerebral perfusion pressure did not differ between blood pressure treatment groups (13.9 ± 5.5 minutes⁻¹ versus 14.8 ± 3.4 minutes⁻¹, P = .38) or vary with mean arterial pressure (r = −0.08, [−0.10, 0.05]).CONCLUSIONS:Perihematoma cerebral perfusion pressure is maintained despite increased cerebrovascular resistance and reduced cerebral blood flow. Aggressive antihypertensive therapy does not affect perihematoma or borderzone cerebral perfusion pressure. Maintenance of cerebral perfusion pressure provides physiologic support for the safety of blood pressure reduction in intracerebral hemorrhage.

Patients with intracerebral hemorrhage (ICH) most often present with elevated blood pressure (BP), but acute treatment remains controversial.^1,2 Despite the results of recent randomized controlled trials of BP management demonstrating no excess of adverse clinical events,^3,4 many physicians are reluctant to aggressively use antihypertensive agents in the acute phase of ICH. This relucence is primarily based on persisting theoretic concerns that there is a zone of tissue at risk for ischemic injury surrounding the acute hematoma.⁵ In addition, more recent MR imaging studies have suggested that subacute ischemic injury occurs in areas remote from the hematoma, including borderzone (BZ, also known as watershed) regions.^6–11 The etiology of these ischemic injuries has been postulated to be hemodynamic compromise secondary to BP reduction.¹⁰ Studies of CBF in the perihematoma region indicate that this region is relatively hypoperfused, but not severely enough to result in ischemia.^12–14 Previous PET studies have demonstrated that the perihematoma region is, in fact, hypometabolic, likely secondary to the primary brain injury, and that the oxygen extraction fraction is not elevated, indicating the absence of misery perfusion.^12,15 Nonetheless, it is possible that reduction of BP will result in a fall in cerebral perfusion pressure (CPP), subsequently precipitating ischemia.¹⁶ In the Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT), we demonstrated that acute BP reduction is not associated with a significant fall in CBF.¹⁷ It has been demonstrated, however, that CPP is more sensitive than CBF or CBV to changes in blood pressure.¹⁸ The relationship between CPP and BP reduction in patients with intracerebral hemorrhage is unknown.Global CPP is normally calculated as the difference between the mean arterial pressure and intracranial pressure, which requires insertion of an intraventricular manometer. Monitoring of intracranial pressure and CPP is generally reserved for patients with a decreased level of consciousness and/or obstructive hydrocephalus requiring ventricular drainage. In these cases, current consensus guidelines recommend that BP be titrated to ensure that CPP is between 50 and 70 mm Hg.^19,20 In addition, global CPP may not reflect local variations in intracranial pressure due to the mass effect of a hematoma, particularly in small hematomas.²¹ Measurements of regional CPP might inform clinical BP management decisions. With PET, it has been demonstrated that CPP can be calculated as a ratio of CBF to CBV.¹⁸ We adapted this technique by using CTP source data from ICH ADAPT to assess local CPP in acute ICH. We tested the hypothesis that aggressive antihypertensive therapy reduces CPP in the perihematoma and borderzone regions.     

Combined Radiofrequency Ablation and Double Anti-Angiogenic Protein Therapy to Increase Coagulation Efficacy: An Experimental Study in a Murine Renal Carcinoma Model

ObjectiveTo evaluate whether suppression of tumor microvasculature by double anti-angiogenic protein (DAAP) treatment could increase the extent of radiofrequency ablation (RFA)-induced coagulation in a murine renal cell carcinoma model.ResultsThe contrast enhancement ratio for tumor vascularization on CEUS was significantly lower in the DAAP treated group than in DAAP-untreated group (30.2 ± 9.9% vs. 77.4 ± 17.3%; p = 0.021). After RFA, the mean coagulation diameter was 0 mm for no-therapy group, 6.7 ± 0.7 mm for the RFA only group and 8.5 ± 0.4 mm for the RFA with DAAP group (ANOVA, p < 0.001). The area of viable mitochondria within the tumor was 27.9 ± 3.9% in no-therapy group, 10.3 ± 4.5% in the RFA only group, and 2.1 ± 0.7% in the RFA with DAAP group (ANOVA, p < 0.001).ConclusionOur results suggest the potential value of combining RFA with anti-angiogenic therapy.     

Spinal multiparametric MRI and DEXA changes over time in men with prostate cancer treated with androgen deprivation therapy: a potential imaging biomarker of treatment toxicity

Objectives

To explore changes in bone mineral density (BMD) measured by DEXA and MRS fat fraction (FF), Dixon FF, and ADC in lower spinal vertebral bodies in men with prostate cancer treated with androgen deprivation therapy (ADT).

Methods

Twenty-eight men were enrolled onto a clinical trial. All received ADT. DEXA imaging was performed at baseline and 12 months. L-spine MRI was done at baseline and 6 months.

Results

The number of patients who underwent DEXA, Dixon, ADC, and MRS at baseline/follow-up were 28/27, 28/26, 28/26, and 22/20. An increase in FF was observed from T11 to S2 (average 1 %/vertebra). There was a positive correlation between baseline MRS FF and Dixon FF (r?=?0.85, p?<?0.0001) and a negative correlation between MRS FF and ADC (r?=?-0.56, p?=?0.036). Over 6 months, MRS FF increased by a median of 25 % in relative values (p?=?0.0003), Dixon FF increased (p?<?0.0001) and ADC values decreased (p?=?0.0014). Men with >5 % BMD loss after 1 year had triple the percentage increase in MRS FF at 6 months (61.1 % vs. 20.9 %, p?=?0.19).

Conclusions

Changes are observed on L-spine MRI after 6 months of ADT. Further investigation is warranted of MRS change as a potential predictive biomarker for later BMD loss.

Key Points

? Spinal marrow fat fraction increases after 6 months of androgen deprivation therapy. ? More inferior vertebral bodies tend to have higher fat fractions. ? MRS fat fraction changes were associated with later changes in DEXA BMD.

     

Reliability of respiratory-triggered two-dimensional cine k-adaptive-t-autocalibrating reconstruction for Cartesian sampling for the assessment of biventricular volume and function in patients with repaired tetralogy of Fallot

Objective:To compare left ventricular (LV) and right ventricular (RV) volume, function, and image quality of a respiratory-triggered two-dimensional (2D)-cine k-adaptive-t-autocalibrating reconstruction for Cartesian sampling (2D kat-ARC) with those of the standard reference, namely, breath-hold 2D balanced steady-state free precession (2D SSFP), in patients with repaired tetralogy of Fallot (TOF).Methods:30 patients (14 males, mean age 32.2 ± 13.9 years) underwent cardiac magnetic resonance, and 2D kat-ARC and 2D SSFP images were acquired on short-axis view. Biventricular end-diastolic volume (EDV) and end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and LV mass (LVM) were analysed.Results:The 2D kat-ARC had significantly shorter scan time (35.2 ± 9.1 s vs 80.4 ± 16.7 s; p < 0.0001). Despite an analysis of image quality showed significant impairment using 2D kat-ARC compared to 2D SSFP cine (p < 0.0001), the two sequences demonstrated no significant difference in terms of biventricular EDV, LVESV, LVSV, LVEF, and LVM. However, the RVESV was overestimated for 2D kat-ARC compared with that for 2D SSFP (73.8 ± 43.2 ml vs 70.3 ± 44.5 ml, p = 0.0002) and the RVSV and RVEF were underestimated (RVSV = 46.2±20.5 ml vs 49.4 ± 20.4 ml, p = 0.0024; RVEF = 40.2±12.7% vs. 43.5±14.0%, p = 0.0002).Conclusion:Respiratory-triggered 2D kat-ARC cine is a reliable technique that could be used in the evaluation of LV volumes and function.Advances in knowledge:2D cine kat-ARC is a reliable technique for the assessment LV volume and function in patients with repaired TOF.