Combined texture analysis of dynamic contrast-enhanced MRI with histogram analysis of diffusion kurtosis imaging for predicting IDH mutational status in gliomas.

BACKGROUND: Non-invasive detection of isocitrate dehydrogenase (IDH) mutational status in gliomas is clinically meaningful for molecular stratification of glioma; however, it remains challenging. PURPOSE: To investigate the usefulness of texture analysis (TA) of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and histogram analysis of diffusion kurtosis imaging (DKI) maps for evaluating IDH mutational status in gliomas. MATERIAL AND METHODS: This retrospective study enrolled 84 patients with histologically confirmed gliomas, comprising IDH-mutant (n = 34) and IDH-wildtype (n = 50). TA was performed for the quantitative parameters derived by DCE-MRI. Histogram analysis was performed for the quantitative parameters derived by DKI. Unpaired Student's t-test was used to identify IDH-mutant and IDH-wildtype gliomas. Logistic regression and receiver operating characteristic (ROC) curve analyses were used to compare the diagnostic performance of each parameter and their combination for predicting the IDH mutational status in gliomas. RESULTS: Significant statistical differences in the TA of DCE-MRI and histogram analysis of DKI were observed between IDH-mutant and IDH-wildtype gliomas (all P < 0.05). Using multivariable logistic regression, the entropy of Ktrans, skewness of Ve, and Kapp-90th had higher prediction potential for IDH mutations with areas under the ROC curve (AUC) of 0.915, 0.735, and 0.830, respectively. A combination of these analyses for the identification of IDH mutation improved the AUC to 0.978, with a sensitivity and specificity of 94.1% and 96.0%, respectively, which was higher than the single analysis (P < 0.05). CONCLUSION: Integrating the TA of DCE-MRI and histogram analysis of DKI may help to predict the IDH mutational status.

Diffusion-relaxation correlation spectrum imaging for predicting tumor consistency and gross total resection in patients with pituitary adenomas: a preliminary study.

OBJECTIVE: To evaluate the ability of diffusion-relaxation correlation spectrum imaging (DR-CSI) to predict the consistency and extent of resection (EOR) of pituitary adenomas (PAs). METHODS: Forty-four patients with PAs were prospectively enrolled. Tumor consistency was evaluated at surgery as either soft or hard, followed by histological assessment. In vivo DR-CSI was performed and spectra were segmented following to a peak-based strategy into four compartments, designated A (low ADC), B (mediate ADC, short T2), C (mediate ADC, long T2), and D (high ADC). The corresponding volume fractions ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]) along with the ADC and T2 values were calculated and assessed using univariable analysis for discrimination between hard and soft PAs. Predictors of EOR > 95% were analyzed using logistic regression model and receiver-operating-characteristic analysis. RESULTS: Tumor consistency was classified as soft (n = 28) or hard (n = 16). Hard PAs presented higher [Formula: see text] (p = 0.001) and lower [Formula: see text] (p = 0.013) than soft PAs, while no significant difference was found in other parameters. [Formula: see text] significantly correlated with the level of collagen content (r = 0.448, p = 0.002). Knosp grade (odds ratio [OR], 0.299; 95% confidence interval [CI], 0.124-0.716; p = 0.007) and [Formula: see text] (OR, 0.834, per 1% increase; 95% CI, 0.731-0.951; p = 0.007) were independently associated with EOR > 95%. A prediction model based on these variables yielded an AUC of 0.934 (sensitivity, 90.9%; specificity, 90.9%), outperforming the Knosp grade alone (AUC, 0.785; p < 0.05). CONCLUSION: DR-CSI may serve as a promising tool to predict the consistency and EOR of PAs. CLINICAL RELEVANCE STATEMENT: DR-CSI provides an imaging dimension for characterizing tissue microstructure of PAs and may serve as a promising tool to predict the tumor consistency and extent of resection in patients with PAs. KEY POINTS: • DR-CSI provides an imaging dimension for characterizing tissue microstructure of PAs by visualizing the volume fraction and corresponding spatial distribution of four compartments ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]). • [Formula: see text] correlated with the level of collagen content and may be the best DR-CSI parameter for discrimination between hard and soft PAs. • The combination of Knosp grade and [Formula: see text] achieved an AUC of 0.934 for predicting the total or near-total resection, outperforming the Knosp grade alone (AUC, 0.785).

Temporal changes in plaque characteristics after treatment and their relationship with stroke recurrence: a quantitative study using magnetic resonance imaging.

Background: Intracranial atherosclerotic disease (ICAD) is the major cause of ischemic stroke. Despite aggressive medical therapy, around 15% of patients with ICAD experience recurrence. The aim of the present study was to evaluate the temporal changes in intracranial arteriosclerotic plaques after medical treatment based on vessel wall magnetic resonance imaging (VWMRI) and to explore their relationship with stroke recurrence. Methods: A total of 67 symptomatic patients with ICAD who underwent initial and follow-up VWMRI were recruited into this retrospective cohort study. Stroke recurrence was defined as an ipsilateral stroke symptom after the initial attack. The clinical characteristics and plaque features, including stenosis ratio (measured based on luminal diameter or area), plaque thickness, plaque burden (PB), enhancement ratio (ER), and enhancement grade, were evaluated and compared between the initial and follow-up examinations. Changes in plaque characteristics were compared between patients with or without recurrence by univariable analyses. Multivariable regression was performed to investigate imaging markers for recurrent stroke. Results: The median interval between baseline and follow-up VWMRI was 334 days. A total of 13 cases (19.4%) experienced a stroke recurrence. After treatment, significant decreases in the stenosis ratio (area), PB, and ER were observed in cases without recurrence (all P<0.05), while no significant difference in plaque features was found for cases with recurrence. Univariable analyses showed that changes in stenosis ratio (area), plaque thickness, PB, and ER were significantly different between patients with and without recurrence (all P<0.05). Multivariable regression indicated that PB change was the only significant marker associated with stroke recurrence [odds ratio (OR) =1.112 per 1% increase, 95% confidence interval (CI): 1.010 to 1.224, P=0.031]. Conclusions: Patients with arteriosclerotic plaques who benefit from medical treatment show obvious decreases in stenosis (area), PB, and ER. The progression of PB may serve as an independent marker for predicting stroke recurrence.

Highly accelerated compressed sensing time-of-flight magnetic resonance angiography may be reliable for diagnosing head and neck arterial steno-occlusive disease: a comparative study with digital subtraction angiography.

INTRODUCTION: We aimed to investigate the utility of compressed sensing time-of-flight magnetic resonance angiography (CS TOF-MRA) for diagnosing intracranial and cervical arterial stenosis by using digital subtraction angiography (DSA) as the reference standard. METHODS: Thirty-seven patients with head and neck arterial stenoses who underwent CS TOF-MRA and DSA were retrospectively enrolled. The reconstructed resolution of CS TOF-MRA was 0.4 × 0.4 × 0.4 mm3. The scan time was 5 min and 2 s. The image quality of CS TOF-MRA was independently ranked by two neuroradiologists in 1031 arterial segments. The luminal stenosis grades on CS TOF-MRA and DSA were analyzed in 61 arterial segments and were compared using the Wilcoxon signed-rank test. The ability of CS TOF-MRA to predict moderate to severe stenosis or occlusion was analyzed. RESULTS: The image quality of most arterial segments (95.2%) on CS TOF-MRA was excellent. Arterial segments with low image quality were mainly the V3-4 segments of the vertebral artery. The majority of arterial stenoses (62.3%) were located in the cervical internal carotid artery. The luminal stenosis grades of CS TOF-MRA were concordant with that of DSA in 50 of 61 segments (p = 0.366). CS TOF-MRA had a sensitivity of 84.4% and a specificity of 88.5% for predicting moderate to severe stenosis. For detecting occlusion lesions, it had a sensitivity of 100% and a specificity of 94.1%. CONCLUSION: CS TOF-MRA provides adequate image quality within a reasonable acquisition time and is a reliable tool for diagnosing head and neck arterial steno-occlusive disease. KEY POINTS: • CS TOF-MRA provides a relatively large coverage (16 cm), high resolution (0.4 × 0.4 × 0.4 mm3) and good image quality of head and neck arteries within 5 min and 2 s. • The diagnostic accuracy of CS TOF-MRA in the assessment of moderate to severe stenosis and occlusion was comparable with that of DSA. • Arterial segments with low image quality were mainly the V3 and V4 segments of the vertebral artery.

Texture Analysis of High b-Value Diffusion-Weighted Imaging for Evaluating Consistency of Pituitary Macroadenomas.

BACKGROUND: Preoperative evaluation of the consistency of pituitary macroadenomas is important for neurosurgeons to prepare the surgical plan. PURPOSE: To evaluate the diagnostic performance of texture analysis (TA) of diffusion-weighted imaging (DWI) at a standard b-value (b = 1000 s/mm2 ) and a high b-value (b = 2000 s/mm2 ) for their ability to assess the tumor consistency of pituitary macroadenomas. STUDY TYPE: Retrospective. POPULATION/SUBJECTS: Fifty patients with histologically confirmed pituitary macroadenomas were classified as soft (n = 37) or hard (n = 13) types. FIELD STRENGTH/SEQUENCE: Coronal T2 -weighted imaging (T2 WI), Readout Segmentation of Long Variable Echo-trains (RESOLVE) DWI at b = 1000 s/mm2 and b = 2000 s/mm2 were acquired with 3.0T MRI. ASSESSMENT: The corresponding apparent diffusion coefficient (ADC) maps (ADC1000 and ADC2000 ) were registered to T2 WI. Regions of interest (ROIs) were manually drawn along the solid part of the tumor from the coregistered T2 WI-ADC images. The texture parameters from T2 WI, ADC1000 , and ADC2000 were acquired. STATISTICAL TESTS: The texture parameters were compared between the two types by using unpaired Student's t-test. Receiver operating characteristic (ROC) curves and logistic regression analyses were used to assess their diagnostic performance. RESULTS: Significant differences in TA parameters of ADC1000 and ADC2000 were observed between soft and hard types (P < 0.05 for all), whereas the TA of T2 WI resulted in no significant difference (P > 0.05 for all). TA of ADC2000 provided a superior diagnostic performance compared with that of ADC1000 (P = 0.038). A combination of mean value and entropy of ADC2000 yielded an AUC, a sensitivity, and a specificity of 0.911, 78.4% and 92.3%, respectively. DATA CONCLUSION: TA of ADC values were useful for assessing the tumor consistency of pituitary macroadenomas. ADC2000 may facilitate better type discrimination. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1507-1513.

Application of Monochromatic Imaging and Metal Artifact Reduction Software in Computed Tomography Angiography after Treatment of Cerebral Aneurysms.

PURPOSE: This study aimed to evaluate the image quality and degree of metal artifact reduction using the new-generation gemstone spectral imaging (GSI) and metal artifact reduction software (MARs) and to demonstrate the optimal monochromatic energy level for dual-energy cerebral computed tomography angiography (CTA) in patients with intracranial aneurysm after endovascular treatment. MATERIAL AND METHODS: A total of 20 patients with cerebral aneurysms treated with coils or clips underwent CTA using gemstone spectral computed tomography. Artifact index was calculated at each energy level with and without MARs. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated on all axial images with MARs; subjective evaluation was done by using a 4-point scale and a 3-point scale for assessing noise and vessel contrast, respectively, and compared between the monochromatic energy levels. RESULTS: The artifact index value of group GSI-MARs was significantly lower than that of group GSI at each monochromatic energy level (all, P < 0.01). Contrast-to-noise ratio and SNR of the parent arteries decreased as the energy increased from 40 to 140 keV in group GSI-MARs (all, P < 0.01). Signal-to-noise ratio and CNR between each 2 adjacent monochromatic energy level showed significant difference (all, P < 0.01). Subjective evaluation showed that a monochromatic energy level between 40 and 70 keV provided the optimal image quality. CONCLUSION: Gemstone spectral imaging with MARs could reduce metal artifacts and improve the image quality of cerebral CTA after coil or clip treatment. The new generation of GSI could provide better CNR and SNR at lower energy level, and the best image quality was obtained at energy level 40 to 70 keV for GSI-MARs.

Intergrating conventional MRI, texture analysis of dynamic contrast-enhanced MRI, and susceptibility weighted imaging for glioma grading.

BACKGROUND: The application of conventional magnetic resonance imaging (MRI) in glioma grading is limited and non-specific. PURPOSE: To investigate the application values of MRI, texture analysis (TA) of dynamic contrast-enhanced MRI (DCE-MRI) and intratumoral susceptibility signal (ITSS) on susceptibility weighted imaging (SWI), alone and in combination, for glioma grading. MATERIAL AND METHODS: Fifty-two patients with pathologically confirmed gliomas who underwent DCE-MRI and SWI were enrolled in this retrospective study. Conventional MRIs were evaluated by the VASARI scoring system. TA of DCE-MRI-derived parameters and the degree of ITSS were compared between low-grade gliomas (LGGs) and high-grade gliomas (HGGs). The diagnostic ability of each parameter and their combination for glioma grading were analyzed. RESULTS: Significant statistical differences in VASARI features were observed between LGGs and HGGs ( P < 0.05), of which the enhancement quality had the highest area under the curve (AUC) (0.873) with 93.3% sensitivity and 80% specificity. The TA of DCE-MRI derived parameters were significantly different between LGGs and HGGs ( P < 0.05), of which the uniformity of Ktrans had the highest AUC (0.917) with 93.3% sensitivity and 90% specificity. The degree of ITSS was significantly different between LGGs and HGGs ( P < 0.001). The AUC of the ITSS was 0.925 with 93.3% sensitivity and 90% specificity. The best discriminative power was obtained from a combination of enhancement quality, Ktrans- uniformity, and ITSS, resulting in 96.7% sensitivity, 100.0% specificity, and AUC of 0.993. CONCLUSION: Combining conventional MRI, TA of DCE-MRI, and ITSS on SWI may help to improve the differentiation between LGGs and HGGs.

Plasma homocysteine levels and intracranial plaque characteristics: association and clinical relevance in ischemic stroke.

BACKGROUND: Elevated plasma homocysteine (Hcy) is an independent risk factor for ischemic stroke. This study aimed to evaluate the association between Hcy levels and intracranial plaque characteristics and to investigate their clinical relevance in ischemic stroke. METHODS: Ninety-four patients with intracranial atherosclerosis (ICAS) were enrolled. Plasma Hcy levels were measured. Intracranial plaque characteristics including plaque enhancement, stenosis ratio, T2 and T1 hyperintense components were assessed on high-resolution magnetic resonance imaging. Logistic regression model was constructed to analyze the association between high Hcy levels and plaque characteristics, and their synergistic effects to predict the likelihood for ischemic stroke, while adjusting for demographics and traditional atherosclerotic risk factors. RESULTS: Elevated Hcy level was associated with strong plaque enhancement independently of age, sex, serum creatinine levels and other atherosclerotic risk factors ((P < 0.001, OR 6.00, 95% confidence interval [CI] 2.28-15.74). Both strong plaque enhancement (P = 0.026, OR 5.63, 95% CI 1.23-25.81) and high Hcy level (P = 0.018, OR 6.20, 95% CI 1.36-28.26) were correlated with acute ischemic stroke. The combination of them strengthened the ability to stratify the likelihood for ischemic stroke, with an improved area under the receiver operating characteristic curve (AUC) of 0.871, significantly higher than that of strong plaque enhancement (0.755) and high Hcy level (0.715) alone (P < 0.05 for both). CONCLUSIONS: High Hcy level appears to have association with intracranial strong plaque enhancement. The combined assessment of plasma Hcy levels and plaque enhancement may improve ischemic stroke risk stratification.

Plaque Distribution and Characteristics in Low-Grade Middle Cerebral Artery Stenosis and Its Clinical Relevance: A 3-Dimensional High-Resolution Magnetic Resonance Imaging Study.

OBJECTIVES: The significance of atherosclerotic plaques in the parental artery with low-grade stenosis remains undetermined. We used three-dimensional high-resolution magnetic resonance imaging (3D HR-MRI) to investigate plaque distribution and characteristics of low-grade middle cerebral artery (MCA) stenosis and its clinical relevance with stroke events. METHODS: We retrospectively studied 22 symptomatic patients and 24 asymptomatic patients with low-grade MCA stenosis (<50%). By 3D HR-MRI, each identified plaque was classified as either culprit (plaque on the ipsilateral side of a stroke) or nonculprit (plaques in asymptomatic patients or not within the vascular territory of a stroke). Plaque enhancement grades and distribution were assessed and compared between the groups. The association between plaque enhancement and distribution and ischemic stroke was evaluated. RESULTS: We identified 22 culprit plaques and 31 nonculprit plaques. More culprit plaques showed contrast enhancement compared to the nonculprit plaques (95.5% versus 29.0%, P <.001). Culprit plaques were more frequently superiorly distributed than the nonculprit plaques (46.9% versus 17.5%, P <.01). Contrast enhancement (odds ratio [OR] 17.0, 95% confidence interval [CI] 3.7-77.4) and superior distribution (OR 4.2, 95% CI 1.4-12.1) of a plaque were associated with a recent ischemic stroke, of which single subcortical infarctions accounted for the largest percentage (50%). CONCLUSIONS: Contrast enhancement and superior distribution may serve as indicators of culprit plaques in low-grade MCA stenosis, and they were significantly related to a recent ischemic stroke.

Ectopic meningioma in a patient with neurofibromatosis Type 2: a case report and review of the literature.

Ectopic meningioma occurring in the region of parapharyngeal space is rare in clinical practice and brings great challenge in its diagnosis. This report details such a case in a 14-year-old girl with neurofibromatosis Type 2, which is a highly infrequent association. The clinical manifestations, imaging findings, and pathological manifestations are described, and the relevant literature is reviewed to highlight characteristic imaging findings of ectopic meningiomas.

MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.

BACKGROUND: Intracranial plaque characteristics are associated with stroke events. Differences in plaque features may explain the disconnect between stenosis severity and the presence of ischemic stroke. PURPOSE: To investigate the relationship between plaque characteristics and downstream perfusion changes, and their contribution to the occurrence of cerebral infarction beyond luminal stenosis. STUDY TYPE: Case control. SUBJECTS: Forty-six patients with symptomatic middle cerebral artery (MCA) stenosis (with acute cerebral infarction, n = 30; without acute cerebral infarction, n = 16). FIELD STRENGTH/SEQUENCE: 3.0T with 3D turbo spin echo sequence (3D-SPACE). ASSESSMENT: Luminal stenosis grade, plaque features including lesion T2 and T1 hyperintense components, plaque enhancement grade, and plaque distribution were assessed. Brain perfusion was evaluated on mean transient time maps based on the Alberta Stroke Program Early CT score (MTT-ASPECTS). STATISTICAL TESTS: Plaque features, grade of luminal stenosis, and MTT-ASPECTS were compared between two groups. The association between plaque features and MTT-ASPECTS were assessed using Spearman's correlation analysis. Multivariate logistic regression and receiver operating characteristic (ROC) curves were constructed to assess the effect of significant variables alone and their combination in determining the occurrence of cerebral infarction. RESULTS: Stronger enhanced plaques were associated with downstream lower MTT-ASPECTS (P = 0.010). Plaque enhancement grade (P = 0.039, odds ratio [OR] 5.9, 95% confidence interval [CI] 1.1-32) and MTT-ASPECTS (P = 0.003, OR 2.6, 95% CI 1.4-4.7) were associated with a recent cerebral infarction, whereas luminal stenosis grade was not (P = 0.128). The combination of MTT-ASPECTS and plaque enhancement grade provided incremental information beyond luminal stenosis grade alone. The area under the receiver operating characteristic curve (AUC) improved from 0.535 to 0.921 (P < 0.05). DATA CONCUSION: Strongly enhanced plaques are associated with a higher likelihood of downstream perfusion impairment. Plaque enhancement and perfusion evaluation may play a complementary role to luminal stenosis in determining the occurrence of acute cerebral infarction. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017.

Orbital benign and malignant lymphoproliferative disorders: Differentiation using semi-quantitative and quantitative analysis of dynamic contrast-enhanced magnetic resonance imaging.

OBJECTIVES: To assess the value of dynamic contrast-enhanced MR imaging (DCE-MRI) in differentiating benign from malignant orbital lymphoproliferative disorders (OLPDs). METHODS: Thirty-nine patients with orbital lymphoproliferative disorders (21 malignant and 18 benign) underwent DCE-MRI scan for pre-treatment evaluation from March 2013 to December 2015. Both semi-quantitative (TTP, AUC, Slopemax) and quantitative (Ktrans, kep, ve) parameters were calculated, and compared between two groups. Receiver operating characteristic (ROC) curve analyses were used to determine the diagnostic value of each significant parameter. RESULTS: Malignant OLPDs showed significantly higher kep, lower ve, and lower AUC than benign OLPDs, while no significant differences were found on Ktrans, TTP and Slopemax. ROC analyses indicated that ve exhibited the best diagnostic performance in predicting malignant OLPDs (cutoff value, 0.211; area under the curve, 0.896; sensitivity, 76.2%; specificity, 94.9%), followed by kep (cutoff value, 0.853; area under the curve, 0.839; sensitivity, 85.7%; specificity, 89.9%). CONCLUSION: DCE-MRI and specially its derived quantitative parameters of kep and ve are promising metrics for differentiating malignant from benign OLPDs.

Radiological indeterminate vestibular schwannoma and meningioma in cerebellopontine angle area: differentiating using whole-tumor histogram analysis of apparent diffusion coefficient.

PURPOSE: To assess the role of whole-tumor histogram analysis of apparent diffusion coefficient (ADC) maps in differentiating radiological indeterminate vestibular schwannoma (VS) from meningioma in cerebellopontine angle (CPA). MATERIALS AND METHODS: Diffusion-weighted (DW) images (b = 0 and 1000 s/mm2) of pathologically confirmed and radiological indeterminate CPA meningioma (CPAM) (n = 27) and VS (n = 12) were retrospectively collected and processed with mono-exponential model. Whole-tumor regions of interest were drawn on all slices of the ADC maps to obtain histogram parameters, including the mean ADC (ADCmean), median ADC (ADCmedian), 10th/25th/75th/90th percentile ADC (ADC10, ADC25, ADC75 and ADC90), skewness and kurtosis. The differences of ADC histogram parameters between CPAM and VS were compared using unpaired t-test. Multiple receiver operating characteristic (ROC) curves analysis was used to determine and compare the diagnostic value of each significant parameter. RESULTS: Significant differences were found on the ADCmean, ADCmedian, ADC10, ADC25, ADC75 and ADC90 between CPAM and VS (all p values < 0.001), while no significant difference was found on kurtosis (p = 0.562) and skewness (p = 0.047). ROC curves analysis revealed, a cut-off value of 1.126 × 10-3 mm2/s for the ADC90 value generated highest area under curves (AUC) for differentiating CPAM from VS (AUC, 0.975; sensitivity, 100%; specificity, 88.9%). CONCLUSIONS: Histogram analysis of ADC maps based on whole tumor can be a useful tool for differentiating radiological indeterminate CPAM from VS. The ADC90 value was the most promising parameter for differentiating these two entities.

Diagnosis and stage of Graves' ophthalmopathy: Efficacy of quantitative measurements of the lacrimal gland based on 3-T magnetic resonance imaging.

The aim of the present study was to determine the efficacy of quantitative measurements of the lacrimal gland based on 3-T magnetic resonance (MR) imaging in the diagnosis and staging of Graves' ophthalmopathy (GO). The study retrospectively enrolled 33 patients with GO (the GO group) and 24 healthy volunteers [the healthy control (HC) group] with orbit MR imaging performed using a 3-T MR scanner. Quantitative parameters of the lacrimal gland, including axial length, axial width, axial area, coronal length, coronal width, coronal area, volume and signal intensity ratio (SIR) of the lacrimal gland to the ipsilateral temporal muscle were measured. The difference of quantitative parameters between the GO and HC groups, or between active and inactive GO groups were evaluated using a Student's t-test. Receiver operating characteristic analyses were used to evaluate the diagnostic value of the significant parameters in discriminating patients with GO from healthy controls, or discriminating active from inactive GO. All the quantitative measurements of the GO patients were significantly larger than those of the healthy controls (P<0.05), with the exception of the coronal length (P=0.150). Axial and coronal width had the best efficacy in discriminating patients with GO from healthy controls. Only SIR was found to be different between the active and inactive GO groups (P=0.001). Setting a SIR of 2.57 as the threshold value, the optimal efficacy was achieved (area under the curve, 0.711; sensitivity, 57.7%; specificity, 77.5%) in discriminating between active and inactive GO. Quantitative measurements of the lacrimal gland based on 3-T MR imaging may assist in the diagnosis and stage of GO.

Utility of histogram analysis of ADC maps for differentiating orbital tumors.

PURPOSE: We aimed to evaluate the role of histogram analysis of apparent diffusion coefficient (ADC) maps for differentiating benign and malignant orbital tumors. METHODS: Fifty-two patients with orbital tumors were enrolled from March 2013 to November 2014. Pretreatment diffusion-weighted imaging was performed on a 3T magnetic resonance scanner with b factors of 0 and 800 s/mm2, and the corresponding ADC maps were generated. Whole-tumor regions of interest were drawn on all slices of the ADC maps to obtain histogram parameters, including ADCmean, ADCmedian, standard deviation (SD), skewness, kurtosis, quartile, ADC10, ADC25, ADC75, and ADC90. Histogram parameter differences between benign and malignant orbital tumors were compared. The diagnostic value of each significant parameter in predicting malignant tumors was established. RESULTS: Age, ADCmean, ADCmedian, quartile, kurtosis, ADC10, ADC25, ADC75, and ADC90 parameters were significantly different between benign and malignant orbital tumor groups, while gender, location, SD, and skewness were not significantly different. The best diagnostic performance in predicting malignant orbital tumors was achieved at the threshold of ADC10=0.990 (AUC, 0.997; sensitivity, 96.2%; specificity, 100%). CONCLUSION: Histogram analysis of ADC maps holds promise for differentiating benign and malignant orbital tumors. ADC10 has the potential to be the most significant parameter for predicting malignant orbital tumors.

Feasibility study of using intravoxel incoherent motion mri to detect parotid gland abnormalities in early-stage Sjögren syndrome patients.

PURPOSE: To determine whether intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) could detect parotid gland abnormalities in Sjögren's syndrome (SS) patients who were not identified by conventional MRI. MATERIALS AND METHODS: Ten consecutive patients with clinically proven SS who were not identified by conventional MRI were assessed by IVIM MRI with a 3.0T MRI scanner. Quantitative parameters (tissue diffusivity, D; pseudodiffusion coefficient, D*; perfusion fraction, f) derived from IVIM MRI were compared between the SS group and healthy control group (n = 15). A receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of each significant parameter. RESULTS: Excellent inter- and intrareader agreements were obtained during the measurement of D, f, and D* values (interreader, 0.980, 0.942, and 0.883; intrareader, 0.991, 0.952, and 0.896, respectively). All three parameters of the SS group were significantly higher than those of the healthy group (D, 1.049 ± 0.056 × 10(-3) mm(2) /s vs. 0.976 ± 0.116 × 10(-3) mm(2) /s, P = 0.012; D*, 20.410 ± 1.786 × 10(-3) mm(2) /s vs. 18.764 ± 2.433 × 10(-3) mm(2) /s, P = 0.013; f, 0.207 ± 0.003 vs. 0.182 ± 0.002, P = 0.004). ROC analysis showed that the f value had the best diagnostic performance (AUC, 0.712; Sensitivity, 0.80; Specificity, 0.57; Cutoff value, 0.185) in detecting the parotid gland abnormalities in early SS patients. CONCLUSION: IVIM MRI detected parotid gland abnormalities in early-stage SS patients. J. Magn. Reson. Imaging 2016;43:1455-1461.

Orbital Indeterminate Lesions in Adults: Combined Magnetic Resonance Morphometry and Histogram Analysis of Apparent Diffusion Coefficient Maps for Predicting Malignancy.

RATIONALE AND OBJECTIVES: The aim of this study was to evaluate the added value of histogram analysis of apparent diffusion coefficient (ADC) maps in differentiating indeterminate orbital malignant tumors from benign tumors, compared to using magnetic resonance (MR) morphological features alone. MATERIALS AND METHODS: We retrospectively evaluated 54 patients with orbital tumors from March 2013 to February 2015. All the patients were assessed by both routine MR and diffusion-weighted imaging, and divided into benign group and malignant group. Routine MR imaging features and histogram parameters derived from ADC maps, including mean ADC (ADCmean), median ADC (ADCmedian), standard deviation, skewness, kurtosis, and 10th and 90th percentiles of ADC (ADC10 and ADC90), were compared between two groups. Univariate and multivariate logistic regression analyses were used to identify the most valuable variables in predicting malignancy. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic value of significant variables. RESULTS: Multivariate logistic regression analysis indicated that two or more quadrants involved, iso-intense on T2-weighted imaging (T2WI), and ADC10 were significant predictors for orbital malignancy. By using model 2 (iso-intense on T2WI + two or more quadrants involved + ADC10 < 0.990) as the criterion, higher AUC and specificity could be achieved than by using model 1 (iso-intense on T2WI + two or more quadrants involved) alone, (model 2 vs model 1; area under curve (AUC), 0.827 vs 0.793; sensitivity, 65.4% vs 69.2%; specificity, 100% vs 89.3%). CONCLUSIONS: Iso-intense on T2WI, two or more quadrants involved, and ADC10 are risk factors for orbital malignancy. Histogram analysis of ADC map might provide added value in predicting orbital malignancy.

Intravoxel incoherent motion MR imaging measurements of the bilateral parotid glands at 3.0-T MR: effect of age, gender and laterality in healthy adults.

OBJECTIVE: To investigate the effect of age, gender and laterality on the intravoxel incoherent motion (IVIM) MR imaging measurements of parotid glands in healthy participants at 3.0-T MRI. METHODS: A total of 108 healthy participants were prospectively recruited. IVIM MRI scan was performed using a 3.0-T MR scanner, and corresponding parameters (perfusion fraction, f; pseudodiffusion coefficient, D*; tissue diffusivity, D) were derived from biexponential fitting of IVIM data. Pearson correlation analysis was performed to determine the association between the IVIM MRI parameters and age. The parameter difference between male and female participants or between left and right parotid glands was compared using unpaired or paired t test, respectively. RESULTS: Excellent interreader and intrareader agreements on the measurements of IVIM MRI parameters were achieved. Both D and f values correlated inversely with the age in both left and right parotid glands (p < 0.05) while D* value did not (p > 0.05). Male participants had higher IVIM MRI parameters than the female participants in both left and right glands (p < 0.05). No significant differences were found in the IVIM MRI parameters between left and right glands in both male and female participants (p > 0.05). CONCLUSION: The IVIM MRI parameters are age and gender dependent, but not laterality dependent. Age- and gender-related effect should be taken into consideration in future IVIM MRI studies for parotid glands. ADVANCES IN KNOWLEDGE: (1) Both D and f values correlated inversely with the age in healthy parotid glands, while D* value did not. (2) The parotid glands of males showed higher IVIM MRI parameters than that of females. (3) There were no significant differences on the IVIM MRI parameters between the left and right glands. (4) Age- and gender-related effect should be taken into consideration in future IVIM MRI studies for parotid glands.

Correlation between cognitive function and the association fibers in patients with Alzheimer's disease using diffusion tensor imaging.

White matter (WM) changes, along with well-characterized cortical abnormalities, occur in patients with Alzheimer's disease (AD). We investigated the integrity of WM tracts within association fibers by the use of fractional anisotropy (FA), and the relationship between FA values and cognitive function in patients with AD. Neuropsychological examination and conventional MRI, as well as diffusion tensor imaging, (DTI) were conducted on 12 patients with mild to moderate AD and 18 cognitively healthy volunteers. DTI was performed to measure FA in the bilateral inferior fronto-occipital fasciculus (IFOF) and the superior longitudinal fasciculus (SLF). Mini-Mental State Examination (MMSE) scores and Montreal Cognitive Assessment (MoCA) values were used to evaluate cognitive function and the Clinical Dementia Rating (CDR) scale was used as a staging tool for dementia severity. FA measures were analyzed and correlated with neuropsychological data. No patient showed any WM tract abnormality on either T1-weighted or T2-weighted MRI. However, the FA values in the bilateral IFOF and SLF and the MoCA scores in patients with AD were significantly decreased (p<0.05) compared to the controls. Furthermore, the decreased FA values in the SLF were positively correlated with cognitive function (MMSE scores - right: r=0.672, p=0.033, left: r=0.919, p<0.01; MoCA values - right: r=0.747, p=0.013, left: r=0.679, p=0.031). Our findings confirmed that the loss of integrity of microstructural WM connectivity has a role in the cognitive decline of patients with AD. The data also suggest that the FA values of the SLF may be used as a clinical marker of cognitive function.

Clinical evaluation and follow-up outcome of diffusion tensor imaging-based functional neuronavigation: a prospective, controlled study in patients with gliomas involving pyramidal tracts.

OBJECTIVE: To evaluate diffusion tensor imaging (DTI)-based functional neuronavigation in surgery of cerebral gliomas with pyramidal tract (PT) involvement with respect to both perioperative assessment and follow-up outcome. METHODS: A prospective, randomized controlled study was conducted between 2001 and 2005. A consecutive series of 238 eligible patients with initial imaging diagnosis of cerebral gliomas involving PTs were randomized into study (n = 118) and control (n = 120) groups. The study cases underwent DTI and three-dimensional magnetic resonance imaging scans. The maps of fractional anisotropy were calculated for PT mapping. Both three-dimensional magnetic resonance imaging data sets and fractional anisotropy maps were integrated by rigid registration, after which the tumor and adjacent PT were segmented and reconstructed for presurgical planning and intraoperative guidance. The control cases were operated on using routine neuronavigation. RESULTS: There was a trend for high-grade gliomas (HGGs) in the study group to be more likely to achieve gross total resection (74.4 versus 33.3%, P < 0.001). There was no significant difference of low-grade gliomas resection between the two groups. Postoperative motor deterioration occurred in 32.8% of control cases, whereas it occurred in only 15.3% of the study cases (P < 0.001). The 6-month Karnofsky Performance Scale score of study cases was significantly higher than that of control cases (86 +/- 20 versus 74 +/- 28 overall, P < 0.001; 93 +/- 10 versus 86 +/- 17 for low-grade gliomas, P = 0.013; and 77 +/- 27 versus 53 +/- 32 for HGGs, P = 0.001). For 81 HGGs, the median survival of study cases was 21.2 months (95% confidence interval, 14.1-28.3 mo) compared with 14.0 months (95% confidence interval, 10.2-17.8 mo) of control cases (P = 0.048). The estimated hazard ratio for the effect of DTI-based functional neuronavigation was 0.570, representing a 43.0% reduction in the risk of death. CONCLUSION: DTI-based functional neuronavigation contributes to maximal safe resection of cerebral gliomas with PT involvement, thereby decreasing postoperative motor deficits for both HGGs and low-grade gliomas while increasing high-quality survival for HGGs.