Independent Poor Prognostic Factors for True Progression after Radiation Therapy and Concomitant Temozolomide in Patients with Glioblastoma: Subependymal Enhancement and Low ADC Value

BACKGROUND AND PURPOSE:Subependymal enhancement and DWI have been reported to be useful MR imaging markers for identifying true progression. Our aim was to determine whether the subependymal enhancement pattern and ADC can differentiate true progression from pseudoprogression in patients with glioblastoma multiforme treated with concurrent chemoradiotherapy by using temozolomide.MATERIALS AND METHODS:Forty-two patients with glioblastoma multiforme with newly developed or enlarged enhancing lesions on the first follow-up MR images obtained within 2 months of concurrent chemoradiotherapy completion were included. Subependymal enhancement was analyzed for the presence, location, and pattern (local or distant relative to enhancing lesions). The mean ADC value and the fifth percentile of the cumulative ADC histogram were determined. A multiple logistic regression analysis was performed to identify independent factors associated with true progression.RESULTS:Distant subependymal enhancement (ie, extending >1 cm or isolated from the enhancing lesion) was significantly more common in true progression (n = 24) than in pseudoprogression (n = 18) (P = .042). The fifth percentile of the cumulative ADC histogram was significantly lower in true progression than in pseudoprogression (P = .014). Both the distant subependymal enhancement and the fifth percentile of the cumulative ADC histogram were independent factors associated with true progression (P = .041 and P = .033, respectively). Sensitivity and specificity for the diagnosis of true progression were 83% and 67%, respectively, by using both factors.CONCLUSIONS:Both the distant subependymal enhancement and the fifth percentile of the cumulative ADC histogram were significant independent factors predictive of true progression.

Glioblastoma multiforme (GBM) is the most common form of malignant primary brain tumor in adults,¹ which is notorious for its intrinsic aggressiveness and a dismal prognosis.^2,3 The current standard treatment for GBM is maximal safe tumor resection followed by radiation therapy with concurrent temozolomide (TMZ) and adjuvant TMZ.⁴Recently, the criteria for assessing therapeutic responses in high-grade gliomas have been updated by the Response Assessment in Neuro-Oncology (RANO) Working Group to address the limitations of the previous guideline.⁵ For instance, contrast enhancement, which has been regarded as a surrogate marker for tumor progression, has been reassessed as a nonspecific finding merely reflecting the passage of contrast material across a disrupted blood-tumor barrier.^6–11 In particular, radiologists and clinicians have increasingly recognized the occurrence of progressive MR imaging lesions immediately after completion of concurrent chemoradiotherapy (CCRT) with TMZ, which spontaneously improved without further treatment other than the adjuvant TMZ.^12–14 The treatment-related reaction is termed pseudoprogression and has received attention as a potential pitfall in the response evaluation. At present, owing to the lack of established findings in conventional contrast-enhanced MR imaging for the differential diagnosis of true progression from pseudoprogression,^9,10 RANO stresses that the diagnosis of true progression can be made within the first 12 weeks after completion of radiation therapy only if most of the new enhancement is located outside the radiation field or if there is pathologic confirmation of progressive disease.⁵During the past few decades, there has been extensive effort to identify imaging biomarkers for tumor progression. Among the many parameters derived from advanced MR imaging techniques, DWI has been consistently reported to be helpful in differentiating tumor progression from treatment-related changes or necrosis.^15–22 Meanwhile, most previous studies pertaining to the role of conventional MR imaging have not shown promising results.^9,23 Nevertheless, a recent study focusing on the conventional MR imaging findings has proposed subependymal enhancement as a useful MR imaging marker for differentiating true progression from pseudoprogression.²⁴ To our knowledge, however, no previous studies have conducted in-depth analysis of the subependymal enhancement, and its potential as an independent predictor for true progression remains elusive.The purpose of the present study was to determine whether the subependymal enhancement pattern and ADC can differentiate true progression from pseudoprogression in patients with GBM treated with radiation therapy and concomitant TMZ.     

低场磁共振成像对强直性脊柱炎的髋关节病变诊断价值

目的探讨低场磁共振成像(MRI)对强直性脊柱炎(AS)髋关节MRI表现,以提高AS的早期诊断。方法对52例AS髋关节的病例进行MRI横、冠状位扫描快速自旋回波(FSE)T2WI,作自旋回波(SE)T1WI,快速自旋回波(FSE-XL)T2WI+脂肪抑制,3D FW FGRE T1WI。男性40例,女性12例,年龄14~58岁,平均30.36岁。结果 52例共104个髋关节有不同程度异常MRI表现,其中累及双侧髋关节47例,单侧5例。MRI表现有:关节积液50例98个髋关节;骨髓水肿19例;关节软骨异常10例;关节面软骨下囊状骨破坏15例;骨质疏松25例;关节间隙狭窄3例;骨质增生和骨赘形成12例;附着点炎症10例。结论 MRI是显示AS的髋关节受累最有效的方法,可用于早期诊断和疾病活动期的评价,为临床治疗、预防提供客观依据。     

Measurement of Opening and Closing Angles of Aortic Valve Prostheses In Vivo Using Dual-Source Computed Tomography: Comparison with Those of Manufacturers' in 10 Different Types

Objective

The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers'' values and to compare CT-measured opening angles according to valve function.

Materials and Methods

A total of 140 patients with 10 different types of mechanical aortic valves, who underwent dual-source cardiac CT, were included. Opening and closing angles were measured on CT images. Agreement between angles in normally functioning valves and the manufacturer values was assessed using the interclass coefficient and the Bland-Altman method. CT-measured opening angles were compared between normal functioning valves and suspected dysfunctioning valves.

Results

The CT-measured opening angles of normally functioning valves and manufacturers'' values showed excellent agreement for seven valve types (intraclass coefficient [ICC], 0.977; 95% confidence interval [CI], 0.962-0.987). The mean differences in opening angles between the CT measurements and the manufacturers'' values were 1.2° in seven types of valves, 11.0° in On-X valves, and 15.5° in ATS valves. The manufacturers'' closing angles and those measured by CT showed excellent agreement for all valve types (ICC, 0.953; 95% CI, 0.920-0.972). Among valves with suspected dysfunction, those with limitation of motion (LOM) and an increased pressure gradient (PG) had smaller opening angles than those with LOM only (p < 0.05).

Conclusion

Dual-source cardiac CT accurately measures opening and closing angles in most types of mechanical aortic valves, compared with the manufacturers'' values. Opening angles on CT differ according to the type of valve dysfunction and a decreased opening angle may suggest an elevated PG.     

Effects of MR Parameter Changes on the Quantification of Diffusion Anisotropy and Apparent Diffusion Coefficient in Diffusion Tensor Imaging: Evaluation Using a Diffusional Anisotropic Phantom

Objective

To validate the usefulness of a diffusional anisotropic capillary array phantom and to investigate the effects of diffusion tensor imaging (DTI) parameter changes on diffusion fractional anisotropy (FA) and apparent diffusion coefficient (ADC) using the phantom.

Materials and Methods

Diffusion tensor imaging of a capillary array phantom was performed with imaging parameter changes, including voxel size, number of sensitivity encoding (SENSE) factor, echo time (TE), number of signal acquisitions, b-value, and number of diffusion gradient directions (NDGD), one-at-a-time in a stepwise-incremental fashion. We repeated the entire series of DTI scans thrice. The coefficients of variation (CoV) were evaluated for FA and ADC, and the correlation between each MR imaging parameter and the corresponding FA and ADC was evaluated using Spearman''s correlation analysis.

Results

The capillary array phantom CoVs of FA and ADC were 7.1% and 2.4%, respectively. There were significant correlations between FA and SENSE factor, TE, b-value, and NDGD, as well as significant correlations between ADC and SENSE factor, TE, and b-value.

Conclusion

A capillary array phantom enables repeated measurements of FA and ADC. Both FA and ADC can vary when certain parameters are changed during diffusion experiments. We suggest that the capillary array phantom can be used for quality control in longitudinal or multicenter clinical studies.     

Primary Pulmonary Low-Grade Angiosarcoma Characterized by Mismatch between 18F-FDG PET and Dynamic Contrast-Enhanced CT

We report a rare case of primary pulmonary low-grade angiosarcoma on dynamic contrast-enhanced CT and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT imaging. A 38-year-old, asymptomatic woman was hospitalized because of an abnormality on chest radiography. A dynamic contrast-enhanced chest CT showed a 1.2 cm-sized irregular-margined nodule with strong and persistent enhancement in the right lower lobe. The lesion had low metabolic activity on an ¹⁸F-FDG PET/CT scan. The patient underwent a wedge resection for the lesion, and pathology revealed a primary pulmonary low-grade angiosarcoma.     

MSCT对健康成人肾上腺体积的测量研究

目的探讨MSCT对健康成人肾上腺体积的测量研究。方法选取2013年1月~2014年6月190例健康体检者作为研究对象,采用多层螺旋CT行增强扫描测量肾上腺体积的大小,着重观察健康成人双侧肾上腺的检出率及其与性别、年龄、体重、身高、血压等参数的关系。结果健康成人双侧肾上腺检出率为100%,左侧平均体积为(2803.18±869.74)mm3,明显大于右侧的(2010.82±726.33)mm3,比较差异有统计学意义(P0.05);男性肾上腺总体积、左侧平均体积、右侧平均体积分别为(5436.91±1576.07)mm3、(3021.48±930.45)mm3、(2448.07±764.95)mm3,均明显大于女性的,(4260.83±1510.34)mm3、(2589.85±880.61)mm3、(1634.90±796.38)mm3,差异有统计学意义(P0.05);双侧肾上腺体积56岁后缩小;肾上腺体积与体重呈正相关,与身高、血压无明显相关性。结论 MSCT可简便、准确测量肾上腺体积,是测量肾上腺的有效方法,为肾上腺病变的影像学诊断提供可靠依据,值得临床推广使用。