Magnetic resonance imaging based on radiomics for differentiating T1-category nasopharyngeal carcinoma from nasopharyngeal lymphoid hyperplasia: a multicenter study.

PURPOSE: To investigate the role of magnetic resonance imaging (MRI) based on radiomics using T2-weighted imaging fat suppression (T2WI-FS) and contrast enhanced T1-weighted imaging (CE-T1WI) sequences in differentiating T1-category nasopharyngeal carcinoma (NPC) from nasopharyngeal lymphoid hyperplasia (NPH). MATERIALS AND METHODS: This study enrolled 614 patients (training dataset: n = 390, internal validation dataset: n = 98, and external validation dataset: n = 126) of T1-category NPC and NPH. Three feature selection methods were used, including analysis of variance, recursive feature elimination, and relief. The logistic regression classifier was performed to construct the radiomics signatures of T2WI-FS, CE-T1WI, and T2WI-FS + CE-T1WI to differentiate T1-category NPC from NPH. The performance of the optimal radiomics signature (T2WI-FS + CE-T1WI) was compared with those of three radiologists in the internal and external validation datasets. RESULTS: Twelve, 15, and 15 radiomics features were selected from T2WI-FS, CE-T1WI, and T2WI-FS + CE-T1WI to develop the three radiomics signatures, respectively. The area under the curve (AUC) values for radiomics signatures of T2WI-FS + CE-T1WI and CE-T1WI were significantly higher than that of T2WI-FS (AUCs = 0.940, 0.935, and 0.905, respectively) for distinguishing T1-category NPC and NPH in the training dataset (Ps all < 0.05). In the internal and external validation datasets, the radiomics signatures based on T2WI-FS + CE-T1WI and CE-T1WI outperformed T2WI-FS with no significant difference (AUCs = 0.938, 0.925, and 0.874 for internal validation dataset and 0.932, 0.918, and 0.882 for external validation dataset; Ps > 0.05). The radiomics signature of T2WI-FS + CE-T1WI significantly performed better than three radiologists in the internal and external validation datasets. CONCLUSION: The MRI-based radiomics signature is meaningful in differentiating T1-category NPC from NPH and potentially helps clinicians select suitable therapy strategies.

Abnormal Topological Organization of White Matter Structural Networks in Normal Tension Glaucoma Revealed via Diffusion Tensor Tractography.

BACKGROUND: Normal tension glaucoma (NTG) is considered a neurodegenerative disease with glaucomatous damage extending to diffuse brain areas. Therefore, this study aims to explore the abnormalities in the NTG structural network to help in the early diagnosis and course evaluation of NTG. METHODS: The structural networks of 46 NTG patients and 19 age- and sex-matched healthy controls were constructed using diffusion tensor imaging, followed by graph theory analysis and correlation analysis of small-world properties with glaucoma clinical indicators. In addition, the network-based statistical analysis (NBS) method was used to compare structural network connectivity differences between NTG patients and healthy controls. RESULTS: Structural brain networks in both NTG and NC groups exhibited small-world properties. However, the small-world index in the severe NTG group was reduced and correlated with a mean deviation of the visual field (MDVF) and retinal nerve fiber layer (RNFL) thickness. When compared to healthy controls, degree centrality and nodal efficiency in visual brain areas were significantly decreased, and betweenness centrality and nodal local efficiency in both visual and nonvisual brain areas were also significantly altered in NTG patients (all p < 0.05, FDR corrected). Furthermore, NTG patients exhibited increased structural connectivity in the occipitotemporal area, with the left fusiform gyrus (FFG.L) as the hub (p < 0.05). CONCLUSIONS: NTG exhibited altered global properties and local properties of visual and cognitive-emotional brain areas, with enhanced structural connections within the occipitotemporal area. Moreover, the disrupted small-world properties of white matter might be imaging biomarkers for assessing NTG progression.

Pretreatment dual-energy CT for predicting early response to induction chemotherapy and survival in nasopharyngeal carcinoma.

OBJECTIVES: To evaluate the predictive performance of pretreatment dual-energy CT (DECT) for early response to induction chemotherapy and survival in nasopharyngeal carcinoma (NPC). METHODS: In this retrospective study, 56 NPC patients who underwent pretreatment DECT scans with posttreatment follow-up were enrolled. The DECT-derived normalised iodine concentration (nIC), effective atomic number (Zeff), 40-180 keV (20 keV interval), and Mix-0.3 value of the tumour lesions were measured to predict the early response to induction chemotherapy and survival in nasopharyngeal carcinoma. The Mann‒Whitney U test, ROC analysis, Kaplan‒Meier method with log-rank test, and Cox proportional hazards model were performed to evaluate the predictive performance of DECT parameters, respectively. RESULTS: Among all DECT-derived parameters, ROC analysis showed the predictive performances of nIC and Zeff values for early objective response to induction chemotherapy (AUCs of 0.803 and 0.826), locoregional failure-free survival (AUCs of 0.786 and 0.767), progression-free survival (AUCs of 0.856 and 0.731) and overall survival (AUCs of 0.765 and 0.799) in NPC patients, respectively (all p < 0.05). Moreover, multivariate analysis showed that a high nIC value was an independent predictor of poor survival in NPC. In addition, survival analysis indicated that NPC patients with higher nIC values in primary tumours tend to have lower 5-year locoregional failure-free survival, progression-free survival and overall survival rates than those with lower nIC values. CONCLUSIONS: DECT-derived nIC and Zeff values can predict early response to induction chemotherapy and survival in NPC; in particular, a high nIC value is an independent predictive factor of poor survival in NPC. CLINICAL RELEVANCE STATEMENT: Preoperative dual-energy computed tomography may provide predictive value for early response and survival outcomes in patients with nasopharyngeal carcinoma, and facilitate their clinical management. KEY POINTS: • Pretreatment dual-energy computed tomography helps to predict early response to therapy and survival in NPC. • NIC and Zeff values derived from dual-energy computed tomography can predict early objective response to induction chemotherapy and survival in NPC. • A high nIC value is an independent predictive factor of poor survival in NPC.

Dual-energy CT for the detection of skull base invasion in nasopharyngeal carcinoma: comparison of simulated single-energy CT and MRI.

BACKGROUND: Skull base invasion in nasopharyngeal carcinoma (NPC) was shown to be a poor negative prognostic factor, and dual-energy CT (DECT) has heralded a new approach to detect this condition. The study aims to evaluate the value of DECT for detection of skull base invasion in NPC and compare the diagnostic performance of DECT with those of simulated single-energy CT (SECT) and MRI. METHODS: The imaging findings of 50 NPC patients and 31 participants in control group which underwent DECT examinations were assessed in this retrospective study. The skull base invasions were evaluated using 5-point scale by two blind observers. ROC analysis, Mcnemar test, paired t test, weighted K statistics and intraclass correlation coefficient were performed to evaluate the diagnostic performance of simulated SECT, MRI and DECT. RESULTS: Quantitative analysis of DECT parameters showed higher normalized iodine concentration and effective atomic number values in sclerosis and lower values in erosion than those in normal bones (both p < 0.05). Compared with simulated SECT and MRI, the diagnostic sensitivity for DECT was significantly improved from 75% (simulated SECT) and 84.26% (MRI) to 90.74% (DECT) (both p < 0.001), specificity from 93.23% and 93.75% to 95.31 (both p < 0.001), accuracy from 86.67% and 90.33% to 93.67%, and AUC from 0.927 and 0.955 to 0.972 (both p < 0.05), respectively. CONCLUSIONS: DECT demonstrates better diagnostic performance than simulated SECT and MRI for detecting skull base invasions in NPC, even those slight bone invasions in early stage, with higher sensitivity, specificity and accuracy.

The alterations of brain network degree centrality in patients with neovascular glaucoma: a resting-state fMRI study.

PURPOSE: To explore the alterations of whole brain functional network using the degree centrality (DC) analysis in neovascular glaucoma (NVG) and the correlation between DC values and NVG clinical indices. MATERIALS AND METHODS: Twenty NVG patients and twenty normal controls (NC), closely matched in age, sex, and education, were recruited for this study. All subjects underwent comprehensive ophthalmologic examinations and a resting-state functional magnetic resonance imaging (rs-fMRI) scan. The differences in DC values of brain network between NVG and NC groups were analyzed, and correlation analysis was performed to explore the relationships between DC values and clinical ophthalmological indices in NVG group. RESULTS: Compared with NC group, significantly decreased DC values were found in the left superior occipital gyrus and left postcentral gyrus, while significantly increased DC values in the right anterior cingulate gyrus and left medial frontal gyrus in NVG group. (All P < 0.05, FDR corrected). In the NVG group, the DC value in left superior occipital gyrus showed significantly positive correlations with retinal nerve fiber layer (RNFL) thickness (R = 0.484, P = 0.031) and mean deviation of visual field (MDVF) (R = 0.678, P = 0.001). Meanwhile, the DC value in the left medial frontal gyrus demonstrated significantly negative correlations with RNFL (R = - 0.544, P = 0.013) and MDVF (R = - 0.481, P = 0.032). CONCLUSIONS: NVG exhibited decreased network degree centrality in visual and sensorimotor brain regions and increased degree centrality in cognitive-emotional processing brain region. Additionally, the DC alterations might be complementary imaging biomarkers to assess disease severity.

Metabolic alterations in the visual pathway of retinitis pigmentosa rats: A longitudinal multimodal magnetic resonance imaging study with histopathological validation.

Because retinitis pigmentosa (RP) has been shown to cause degenerative changes in the entire visual pathway, there is an urgent need to perform longitudinal assessments of RP-induced degeneration and identify imaging protocols to detect this degeneration as early as possible. In this study, we assessed a transgenic rat model of RP by using complementary noninvasive magnetic resonance imaging techniques, namely, proton magnetic resonance spectroscopy (1 H-MRS), to investigate the metabolic changes in RP. Our study demonstrated decreased concentrations and ratios to creatine (Cr) of N-acetylaspartate (NAA), glutamate (Glu), γ-aminobutyric acid (GABA), and taurine (Tau), whereas myo-inositol (Ins) and choline (Cho) were increased in the visual cortex of Royal College of Surgeons (RCS) rats compared with control rats (p < 0.05). Furthermore, with the progression of RP, the concentrations of NAA, Glu, GABA, and Tau, and the ratios of GABA/Cr and Tau/Cr significantly decreased over time, whereas the concentrations of Ins and Cho and the ratio of Ins/Cr significantly increased over time (p < 0.05). In addition, in RCS rats, NAA/Cr decreased significantly from 3 to 4 months postnatal (p < 0.001), and Cho/Cr increased significantly from 4 to 5 months postnatal (p = 0.005). Meanwhile, the 1 H-MRS indicators in 5-month postnatal RCS rats could be confirmed by immunohistochemical staining. In conclusion, with the progression of RP, the metabolic alterations in the visual cortex indicated progressive reprogramming with the decrease of neurons and axons, accompanied by the proliferation of gliocytes.

Extramedullary Plasmacytoma of the Sinonasal Cavity: Magnetic Resonance Imaging Characteristics With Readout-Segmented Diffusion-Weighted Imaging and Dual-Energy Computed Tomography Features.

PURPOSE: To determine magnetic resonance imaging (MRI) with readout-segmented diffusion-weighted imaging (RESOLVE-DWI) and dual-energy computed tomography (DECT) features of sinonasal extramedullary plasmacytoma (SN-EMP). METHODS: The MRI and/or DECT of 10 patients with SN-EMP confirmed by pathology were retrospectively reviewed. Apparent diffusion coefficient (ADC) values of RESOLVE-DWI were analyzed in 9 patients. The quantitative parameters derived from DECT, including the iodine concentration (IC), effective atomic number, and the slope (k) of spectral attenuation curve, were measured in 3 patients. RESULTS: On conventional MRI, typical lesions were well defined (7 of 9), and isointense to the brain on both T1WI and T2WI (9 of 9). Most lesions presented with marked enhancement on contrast-enhanced T1WI without significant necrosis (8 of 9). Notably, multiple flow-void signals were observed in all lesions (9 of 9). On RESOLVE-DWI, the average ADC value was 0.55 × 10-3 mm2/s, and the normalized ADC value was 0.66 ± 0.04. On DECT, the average values of IC, effective atomic number, and slope (k) was 2.7 mg/mL, 8.62, and 3.8, respectively. CONCLUSIONS: Some typical MRI features (well-defined mass, isointensity to the brain, marked enhancement without obvious cystic changes, multiple flow voids, and a lower ADC value) strongly suggest the diagnosis of SN-EMP. The quantitative parameters derived from RESOLVE-DWI and DECT may provide more information for the diagnosis of SN-EMP.

Dual-energy CT in differentiating benign sinonasal lesions from malignant ones: comparison with simulated single-energy CT, conventional MRI, and DWI.

OBJECTIVES: To explore the value of dual-energy CT (DECT) for differentiating benign sinonasal lesions from malignant ones, and to compare this finding with simulated single-energy CT (SECT), conventional MRI (cMRI), and diffusion-weighted imaging (DWI). METHODS: Patients with sinonasal lesions (38 benign and 34 malignant) who were confirmed by histopathology underwent DECT, cMRI, and DWI. DECT-derived parameters (iodine concentration (IC), effective atomic number (Eff-Z), 40-180 keV (20-keV interval), virtual non-enhancement (VNC), slope (k), and linear-mixed 0.3 (Mix-0.3)), DECT morphological features, cMRI characteristics, and ADC value of benign and malignant tumors were compared using t test or chi-square test. Receiver operating characteristic (ROC) curve was performed to evaluate the diagnostic performance, and the area under the ROC curve (AUC) was compared using the Z test to select the optimal diagnostic approach. RESULTS: Significantly higher DECT-derived single parameters (IC, Eff-Z, 40 keV, 60 keV, 80 keV, slope (k), Mix-0.3) were found in malignant lesions than those of benign sinonasal lesions (all p < 0.004, Bonferroni correction). Combined quantitative parameters (IC, Eff-Z, 40 keV, 60 keV, 80 keV, slope (k)) can improve the diagnostic efficiency for discriminating these two entities. Combination of DECT quantitative parameters and morphological features can further improve the overall diagnostic performance, with AUC, sensitivity, specificity, and accuracy of 0.935, 96.67%, 90.00%, and 93.52%. Moreover, the AUC of DECT was higher than those of Mix-0.3 (simulated SECT), cMRI, DWI, and cMRI+DWI. CONCLUSIONS: Compared with simulated SECT, cMRI, and DWI, DECT appears to be a more accurate imaging technique for differentiating benign from malignant sinonasal lesions. KEY POINTS: • DE can differentiate benign sinonasal lesions from malignant ones based on DECT-derived qualitative parameters. • DECT appears to be more accurate in the diagnosis of sinonasal lesions when compared with simulated SECT, cMRI, and DWI.

BLADE turbo gradient- and spin-echo in the assessment of sinonasal lesions: a comprehensive comparison of image quality in readout-segmented echo-planar imaging.

BACKGROUND: A two-dimensional turbo gradient-echo and spin-echo diffusion-weighted pulse sequence with a non-Cartesian BLADE trajectory (TGSE BLADE) can eliminate image artifacts and distortion with clinically acceptable scan times. This process has the potential to overcome the shortcomings of current diffusion-weighted imaging (DWI) techniques, especially in the sinonasal region. PURPOSE: To investigate the feasibility of TGSE BLADE in the assessment of sinonasal lesions and compare the quality of TGSE BLADE with RESOLVE images both qualitatively and quantitatively. MATERIAL AND METHODS: A total of 36 patients with sinonasal lesions were included in this prospective study. DW images acquired using TGSE BLADE and RESOLVE were performed with the same acquisition time. Two independent observers evaluated the qualitative parameters (overall image quality, lesion visibility, and geometric distortion) and quantitative parameters (geometric distortion ratio [GDR], signal-to-noise ratio [SNR], contrast, contrast-to-noise ratio [CNR], and apparent diffusion coefficient [ADC] value) of the two sequences. RESULTS: Qualitative assessment revealed that TGSE BLADE exhibited higher overall image quality (P < 0.001) and lesion visibility (P < 0.001) and less geometric distortion (P < 0.001) than RESOLVE. Quantitative assessment showed that TGSE BLADE images exhibited higher contrast (P < 0.001) and CNR (P < 0.001) and lower GDR (P < 0.05) and SNR (P < 0.001) than RESOLVE images. The ADC value of TGSE BLADE was significantly lower than that of RESOLVE (P < 0.05). CONCLUSION: TGSE BLADE can reduce susceptibility artifacts and geometric distortion more than RESOLVE and appears to be a promising diffusion imaging sequence for the assessment of sinonasal lesions.

Magnetic resonance imaging investigations reveal that PM2.5 exposure triggers visual dysfunction in mice.

OBJECTIVES: To investigate how PM2.5 exposure affects the microstructure, metabolites or functions of the visual system. METHODS: C57BL/6J mice were randomly assigned to groups exposed to the filtered air (the control group) or the concentrated ambient PM2.5 (the PM2.5 group). Visual evoked potentials (VEP), electroretinograms (ERG), diffusion tensor imaging (DTI), proton magnetic resonance spectroscopy (1H-MRS) and resting-state functional MRI (rsfMRI) were performed. Parameters were obtained and compared between the two groups, including latencies and amplitudes of the P1 wave, N1 wave and P2 wave from VEP, latencies and amplitudes of the a wave and b wave from ERG, fractional anisotropy (FA), mean diffusion (MD), axial diffusivity (AD) and radial diffusivity (RD) from DTI, visual cortex (VC) metabolites from 1H-MRS, and regional homogeneity (ReHo) from rsfMRI. RESULTS: Compared with the values of the control group, the PM2.5 group showed a prolonged N1 latency (43.11 ±â€¯7.94 ms vs. 38.75 ±â€¯4.60 ms) and lowered P1 amplitude (5.62 ±â€¯4.38 µV vs. 8.56 ±â€¯5.92 µV) on VEP (all p < 0.05). On ERG, the amplitude of the a wave was lowered (- 91.39 ±â€¯56.29 µV vs. - 138.68 ±â€¯89.05 µV), the amplitude of the b wave was lowered (194.38 ±â€¯126.27 µV vs. 284.72 ±â€¯170.99 µV), and the latency of the b wave was prolonged (37.78 ±â€¯10.72 ms vs. 33.01 ±â€¯4.34 ms) than the values of the control group (all p < 0.05). DTI indicated FA increase in the bilateral piriform cortex (Pir), FA decrease in the bilateral somatosensory cortex (S) and the bilateral striatum (Stri), AD decrease in the bilateral VC, the right S and the bilateral Pir, MD decrease in the bilateral Pir, and RD decrease in the bilateral Pir in the PM2.5 mice (all p < 0.05, Alphasim corrected). 1H-MRS showed Glutamate (Glu) increase and Phosphocholine (PCh) increase in the VC of the PM2.5 group than those of the control group (PCh 1.63 ±â€¯0.25 vs. 1.50 ±â€¯0.25; PCh/total creatine(tCr) 0.19 ±â€¯0.03 vs. 0.18 ±â€¯0.03; Glu 10.46 ±â€¯1.50 vs. 9.60 ±â€¯1.19; Glu/tcr 1.23 ±â€¯0.11 vs. 1.12 ±â€¯0.11) (all p < 0.05). rsfMRI showed higher ReHo in the PM2.5 mice in the left superior colliculus, the left motor cortex, the hippocampus, the periaqueductal gray and the right mesencephalic reticular formation (all p < 0.01, AlphaSim corrected). CONCLUSIONS: This study revealed that PM2.5 exposure triggered visual dysfunction, and altered microstructure, metabolite and function in the retina and visual brain areas along the visual system.

Dual-energy CT in predicting Ki-67 expression in laryngeal squamous cell carcinoma.

PURPOSE: To investigate whether multiple dual-energy computed tomography (DECT) parameters can noninvasively predict the Ki-67 expression (associated with survival and prognosis) in laryngeal squamous cell carcinoma (LSCC). METHODS: Eighty-eight patients with histologically proven LSCC were retrospectively reviewed. Multiple DECT-derived parameters were measured and correlated with Ki-67 expression by Spearman correlation analysis. Comparisons of the DECT-derived parameters between tumors with low- and high-level expression of Ki-67 were made with the t-tests. RESULTS: The iodine concentration (IC), normalized IC (NIC), effective atomic number (Zeff), 40-80 keV, and slope (k) values were positively correlated with Ki-67 expression (all p < 0.05, rho=0.367-0.548). Among all DECT-derived parameters, NIC value had the highest r value in correlation with Ki-67 expression. The IC, NIC, Zeff, 40-80 keV, and slope (k) values were significantly higher in LSCC with high Ki-67 expression than in those with low Ki-67 expression (all p < 0.05). CONCLUSIONS: Multiple DECT-derived parameters (IC, NIC, Zeff, 40-80 keV, and slope (k)) can be used as predictors of survival and prognosis in LSCC, among which the NIC value is the strongest.

Altered spontaneous neuronal activity and functional connectivity pattern in primary angle-closure glaucoma: a resting-state fMRI study.

PURPOSE: To explore the alterations of spontaneous neuronal activity and functional connectivity pattern using fractional amplitude of low-frequency fluctuation (fALFF) and functional connectivity (FC) in patients with primary angle-closure glaucoma (PACG) and fALFF relationship with the glaucoma clinical indices. MATERIALS AND METHODS: Forty-two PACG patients and 21 normal controls were enrolled in this study. Resting-state functional magnetic resonance imaging was firstly analyzed by fALFF and brain regions with altered fALFF between groups were selected as seeds for the further FC analysis. The relationships between fALFF/FC values of abnormal regions and ophthalmological measures, including mean deviation of visual field (MDVF) and retinal nerve fiber layer (RNFL) thickness, were also analyzed. RESULTS: Compared with NC, PACG had significant lower fALFF values in the left cuneus, left middle temporal gyrus, right middle temporal gyrus, and right precentral gyrus, while higher fALFF values in the bilateral superior frontal gyrus (P < 0.05 after correction). Furthermore, PACG showed increased FC between left cuneus and bilateral superior frontal gyrus/bilateral posterior cingulate gyrus; between left middle temporal gyrus and bilateral superior frontal gyrus; and between right middle temporal gyrus and bilateral insular (P < 0.05 after correction). In addition, in the PACG group, the mean fALFF values of the left cuneus were positively correlated with MDVF (R = 0.419, P = 0.005) and RNFL thickness (R = 0.322, P = 0.038). Meanwhile, the mean fALFF values of bilateral superior frontal gyrus were negatively correlated with MDVF (R = - 0.454, P = 0.003) and RNFL thickness (R = - 0.556, P < 0.001). CONCLUSIONS: PACG exhibited abnormal spontaneous neural activity and connectivity in several brain regions mainly associated with visual and visual-related functions. In addition, the fALFF values of the left cuneus and bilateral superior frontal gyrus may be complementary biomarkers for assessing the disease severity.

Dual-energy CT in the differentiation of stage T1 nasopharyngeal carcinoma and lymphoid hyperplasia.

PURPOSE: To explore the value of dual-energy CT for the differentiation between stage T1 nasopharyngeal carcinoma (NPCT1) and lymphoid hyperplasia (LH). METHOD: Patients with histopathological proven nasopharyngeal lesions (stage T1 NPCs, n = 30; LHs, n = 47) who underwent dual-energy CT were enrolled in this retrospective study. Quantitative parameters derived from dual-energy CT were measured. Statistical analyses were performed using the independent sample t-test, Wilcoxon rank sum test, and receiver operating characteristic curve (ROC) analysis. RESULTS: There was significantly higher iodine concentration (IC), normalized iodine concentration (NIC, to internal jugular vein) in NPCT1 compared with LH (p < 0.001). The effective atomic number (Zeff) was significantly higher in NPCT1 than that in LH (p < 0.001). The virtual monochromatic images (VMIs) at 50 keV-110 keV (20 keV-interval) of NPCT1 were all significantly higher than those of LH (all p <0.001). The slope (k) value of spectral attenuation curve was also significantly higher in NPCT1 than LH (p < 0.001). There was no significant difference in virtual noncontrast (VNC) and 130 keV-190 keV (20 keV-interval) between the NPCT1 and LH. For discriminating NPCT1 from LH, the area under curve (AUC) using 70 keV was the highest in all single parameter (AUC, 0.92; sensitivity, 80.00 %; specificity, 91.49 %). Combined multiple parameters (IC, NIC, Zeff, 50 keV, 70 keV, 90 keV, slope (k)) by performing multivariate logistic regression model significantly improve the diagnostic capability in differentiating these two entities, with AUC, sensitivity, and specificity values of 0.99, 93.33 %, 97.87 %, respectively. CONCLUSIONS: Dual-energy CT can be helpful for the differentiation between NPCT1 and LH lesions.

Whole-tumor histogram analysis of monoexponential and advanced diffusion-weighted imaging for sinonasal malignant tumors: Correlations with histopathologic features.

BACKGROUND: The histopathological basis of monoexponential diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI) in the characterization of sinonasal malignant tumors is still unclear. PURPOSE: To explore the correlations of histogram metrics from monoexponential DWI, IVIM, and DKI with histopathologic features in sinonasal malignant tumors. STUDY TYPE: Retrospective. SUBJECTS: In all, 76 patients with sinonasal malignant tumors. FIELD STRENGTH/SEQUENCE: Fourteen different b values (b = 0, 50, 100, 150, 200, 250, 300, 350, 400, 800, 1000, 1500, 2000, and 2500 sec/mm2 ) were used to perform different DWI models at 3.0T. ASSESSMENT: The whole-tumor histogram metrics were calculated on the apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), diffusion kurtosis (K), and diffusion coefficient (Dk) maps. Histopathologic features, including nuclear, cytoplasmic, cellular, stromal fractions, and the nuclear-to-cytoplasmic (N/C) ratio, were measured. STATISTICAL TESTS: Spearman correlations and stepwise multiple linear regression analyses were performed to determine the correlations between histogram metrics and histopathologic features. RESULTS: ADC, Dk, and f histogram metrics showed significant correlations with investigated histopathologic features; D and K histogram metrics were significantly correlated with cellular, stromal, and nuclear fractions (all P < 0.05). Significant correlations between the 75th percentile of D and cytoplasmic fraction and between the kurtosis of K and the N/C ratio were observed (P < 0.05). The skewness of Dk, K, and the 75th percentile of D were independently associated with cellular and nuclear fractions; the skewness of Dk and K were independently associated with stromal fraction (P < 0.05). DATA CONCLUSION: Monoexponential and advanced DWI histogram parameters were significantly correlated with histopathologic features in sinonasal malignancies. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:273-285.

Diffusion Kurtosis Imaging and Intravoxel Incoherent Motion in Differentiating Nasal Malignancies.

OBJECTIVES/HYPOTHESIS: To evaluate the usefulness of diffusion kurtosis imaging (DKI) and intravoxel incoherent motion (IVIM) in the differentiation of sinonasal malignant tumors (SNMTs) with different histological types. STUDY DESIGN: Retrospective observational and diagnostic study. METHODS: Sixty-five patients with SNMTs who underwent DKI and IVIM were enrolled in this retrospective study, including 27 squamous cell carcinomas (SCCs), 13 olfactory neuroblastomas (ONBs), 14 malignant melanomas (MMs) and 11 lymphomas. The kurtosis (K) and diffusion coefficient (Dk) from DKI and the pure diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), and the product of D* and f (f∙D*) from IVIM were measured. Kruskal-Wallis and Dunn multiple comparison tests with Bonferroni correction, receiver operating characteristic curve, and logistic regression analyses were used for statistical analysis. RESULTS: Lymphomas demonstrated the highest K values but lowest Dk, D, D*, f, and f∙D* values among these four malignant tumors. ONBs exhibited high K values and MMs had highest D*, f, and f∙D* values. The cutoff value of ≤0.887 × 10-3 mm2 /sec for f∙D* provided a sensitivity, specificity, and an accuracy of 100%, 98.1%, and 98.5%, respectively, for differentiating lymphomas from the other three entities. The combination of f∙D* and D values showed a sensitivity of 92.9% and a specificity of 92.5% for the discrimination of MMs from ONBs and SCCs. The K value was useful for differentiating ONBs from SCCs, with a threshold value of 0.942 (sensitivity, 84.6%; specificity, 63.0%). CONCLUSIONS: The combined use of DKI and IVIM is helpful for differentiating among four histological types of SNMTs. LEVEL OF EVIDENCE: 3 Laryngoscope, 2019.

Differentiation between sinonasal natural killer/T-cell lymphomas and diffuse large B-cell lymphomas by RESOLVE DWI combined with conventional MRI.

OBJECTIVE: To explore the feasibility of using RESOLVE DWI combined with conventional magnetic resonance imaging (MRI) to discriminate between sinonasal NKTLs and DLBCLs and to investigate the correlation between ADC value and Ki-67 expression in the two subtypes of NHLs. MATERIALS AND METHODS: Sixty patients with NKTLs and twenty-six patients with DLBCLs in the sinonasal region who were confirmed by histopathology underwent high-resolution DWI and conventional MRI. The apparent diffusion coefficients (ADCs) and conventional MRI features associated with NKTLs and DLBCLs were compared using multivariate logistic regression. Receiver operating characteristic (ROC) curve analysis was performed, and the area under the curve (AUC) values for conventional MRI and MRI in combination with DWI were compared to determine the diagnostic performances of the approaches in the differentiation of NKTLs and DLBCLs. Spearman's rank correlations were used to analyze the correlation between ADC value with the higher AUC and Ki-67 expression. RESULTS: For conventional MRI, localization in the nasal cavity and poor or moderate enhancement indicated an NKTL, whereas localization in the paranasal sinus and intense enhancement indicated a DLBCL, with sensitivity, specificity and area under the curve(AUC)value of 88.5%, 85.0% and 0.883, respectively. A combination with a cut-off ADC value of 0.646 × 10-3 mm2/s yielded sensitivity, specificity and AUC values of 100.0%, 80.0% and 0.951, respectively. A significant difference between the AUCs for conventional MRI and MRI in combination with DWI (p = 0.02) was identified. Ki-67 expression of NKTLs was significantly lower than that of DLBCLs (p < 0.001). Besides, there was an inversely poor correlation between them in the overall sample (r = -0.395, p < 0.001). However, the ADC value was not significantly correlated with Ki-67 LI in neither NKTLs nor DLBCLs (both p > 0.05). CONCLUSIONS: Location and enhancement degree were the most valuable conventional MRI features for differentiating between NKTLs and DLBCLs. A combination of DWI and MRI could significantly improve the differential performance. ADC values may be used to noninvasively evaluate the proliferation level of sinonasal NHLs.

Metabolic Alterations Within the Primary Visual Cortex in Early Open-angle Glaucoma Patients: A Proton Magnetic Resonance Spectroscopy Study.

PURPOSE: To detect changes in metabolites and explore cortical plasticity at the metabolic level within the primary visual cortex through proton magnetic resonance spectroscopy in early open-angle glaucoma (OAG) patients. METHODS: A total of 23 symmetrically bilateral early OAG patients and 21 normal controls (NC) were recruited as the early OAG group and NC group, respectively. All subjects underwent a proton magnetic resonance examination, and then, the N-acetylaspartate (NAA), glutamine-glutamate (Glx), myo-inositol (Ins), choline (Cho), and creatine (Cr) concentrations within the bilateral primary visual cortex were determined. The mean NAA/Cr ratio, mean Cho/Cr ratio, mean Glx/Cr ratio, and mean Ins/Cr ratio of the bilateral sides were compared between early OAG patients and NC using the independent samples t test. RESULTS: Compared with NC, the mean Glx/Cr ratio (corrected P=0.003) in primary visual cortex was significantly higher, whereas the mean Ins/Cr ratio (corrected P=0.001) was statistically lower in early OAG patients. However, no apparent difference was found in the mean Cho/Cr ratio or mean NAA/Cr ratio between the OAG group and NC group. CONCLUSIONS: Abnormal metabolites were found in our study through proton magnetic resonance spectroscopy and could contribute to cortical plasticity of the primary visual cortex in early OAG patients.

White Matter Abnormalities and Correlation With Severity in Normal Tension Glaucoma: A Whole Brain Atlas-Based Diffusion Tensor Study.

Purpose: To detect injury of whole brain white matter (WM) in normal tension glaucoma (NTG) patients by using diffusion tensor imaging (DTI) and to analyze the correlations between DTI parameters and glaucoma indices. Methods: Twenty mild, 17 moderate, and 18 severe NTG patients as well as 25 normal subjects were enrolled in this study. Atlas-based diffusion tensor analysis was performed to measure the fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). One-way analyses of variance were used for comparisons of DTI parameters between NTG subgroups and normal control (NC) group. The relationships between DTI parameters and glaucoma indices were also assessed by Pearson's correlation and "broken-stick" analyses. Results: As compared with NC subjects, significantly decreased FA and AD and increased MD and RD were observed in the bilateral posterior thalamic radiation, bilateral sagittal stratum, bilateral cingulum-hippocampus, and bilateral fornix/stria terminalis in NTG patients. The DTI parameters of these WM regions correlated with the mean deviation of visual field (MDVF) and retinal nerve fiber layer (RNFL) thickness. Additionally, there was a tipping point between MDVF and DTI parameters as well as between MDVF and RNFL thickness. Conclusions: Atlas-based DTI analysis was capable of indicating WM damage in the four regions associated with visual and visual-related functions in NTG patients, and it could also be used for investigating disease progression and pathologic changes. In addition, WM impairment and RNFL thinning occurred before patients showed detectable visual field loss.