MK Values Research Articles

Fast diffusion kurtosis imaging for venous stroke caused by cerebral venous thrombosis

Background: Diffusion kurtosis imaging (DKI) has been found to be more precise than diffusion weighted imaging (DWI) for detecting irreversible infarction in acute ischemic stroke. This study aimed to evaluate whether fast DKI has distinctive advantages in detecting venous stroke caused by cerebral venous thrombosis (CVT). Methods: All data from patients diagnosed with venous stroke due to CVT and qualified for mechanical recanalization treatment were collected. Fast DKI and DWI were obtained both before and after revascularization therapy, and lesions were measured. Lesion volumes on T2 weighted imaging (T2WI) were followed up at six months. Results: A total of 11 patients were recruited. Compared to the contralateral brain, ADC values of the lesions in pre-operation increased significantly (1340.12±235.42 vs 919.75±128.98, P < 0.05), while MK decreased (0.59±0.11 vs 0.81±0.12, P < 0.05). And the same changing trend about ADC values (1258.94±185.08 vs 949.81±148.52, P < 0.05) and MK values (0.64±0.12 vs 0.83±0.12, P < 0.05) in post-operation. There was no significant difference in the volume of lesions between DKI and DWI during the same examination period (26.97 vs 29.28, Ppre > 0.05; 13.34 vs 13.14, Ppost > 0.05). However, the lesion volume after revascularization was significantly reduced compared to the first DKI and DWI examinations (26.97 vs 13.34, P < 0.05), and the same as DWI (29.28 vs 13.14, P < 0.05). Volume of T2WI lesions after the 6th month diminished significantly compared with both DKI lesions and DWI lesions before treatment (7.25 vs 26.97, P < 0.05; 7.25 vs 31.19, P < 0.05). Fast DKI had a higher signal to noise ratio (SNR) than traditional DKI and DWI. Conclusion: The MK of the venous stroke lesions decreased significantly in the subacute stage of CVT, suggesting reversible infarction. Fast DKI has more distinctive superiority in the evaluation of venous stroke. Fast DKI approach may hold great promise for patients in clinical setting because of a higher SNR than DWI. But the sample need to be further expanded because of only 11 patients recruited.

Restriction Spectrum Imaging and Diffusion Kurtosis Imaging for Assessing Proliferation Status in Rectal Carcinoma

To investigate the application of the three-compartment restriction spectrum imaging (RSI) model, diffusion kurtosis imaging (DKI), and diffusion-weighted imaging (DWI) in predicting Ki-67 status in rectal carcinoma. A total of 80 rectal carcinoma patients, including 47 high-proliferation (Ki-67> 50%) cases and 33 low-proliferation (Ki-67≤ 50%) cases, underwent pelvic MRI were enrolled. Parameters derived from RSI (f1, f2, and f3), DKI (MD and MK), and DWI (ADC) were calculated and compared between the two groups. Logistic regression (LR) analysis was conducted to identify independent predictors and assess combined diagnosis. Area under the receiver operating characteristic curve (AUC), DeLong analysis, and calibration curve analyses were performed to evaluate diagnostic performance. The patients with high-proliferation rectal carcinoma exhibited significantly higher f1 and MK values and significantly lower ADC, MD, f2, and f3 values than those with low-proliferation rectal carcinoma (P<0.05). LR analysis showed that MD, MK, and f2 were independent predictors for Ki-67 status in rectal carcinoma. Moreover, the combination of these three parameters achieved an optimal diagnostic efficacy (AUC = 0.877, sensitivity = 80.85%, specificity = 84.85%) that was significantly better than that obtained using ADC (AUC = 0.783, Z=2.347, P=0.019), f2 (AUC = 0.732, Z=2.762, P=0.006), and f3 (AUC = 0.700, Z=3.071, P=0.002). The combined diagnosis also showed good performance (AUC = 0.859) in the internal validation analysis based on 1000 bootstrap samples, while the calibration curve demonstrated that the combined diagnosis provided good stability. RSI, DKI, and DWI can effectively differentiate between patients with high- and low-proliferation rectal carcinoma. Furthermore, the MD, MK, and f2 imaging parameters may be a novel and promising combination biomarker for examining Ki-67 status in rectal carcinoma.

Correction on stress intensity factor of root within pipeline girth weld considering various geometric parameters

The study focuses on the stress intensity correction factor (Mk) for internal surface cracks located at the girth pipe root toe. To assess the impact of various parameters on Mk, three-dimensional finite element models are developed. These models take different types of misalignment, a range of variable-wall-thickness ratios, and initial crack depths into account. The findings reveal that the stress intensity correction factor Mk tends to increase with the rise in misalignment and variable-wall-thickness ratio. Conversely, an increase in the initial crack depth leads to a decrease in Mk. The study demonstrates that the Mk values, when accounting for different geometric factors, are significantly higher than those calculated using BS 7910. This suggests that the BS 7910 standard may provide overly optimistic predictions. As a result, a revised Mk formula is proposed, which generally maintains an error margin of less than 10 %. This modified formula offers a significant enhancement to prevailing codes and standards, furnishing a more dependable benchmark for the assessment of structural integrity in pipeline laying procedures.

Optimal design of optomechanical uncooled infrared focal plane array with integrated metalens

Optomechanical uncooled infrared (IR) detectors based on the thermal deformation of bi-material micro-cantilever have proved of significant potential in the IR imaging fields. However, compared to other uncooled infrared detectors, the optomechanical type relies on the mechanical deformation of the thermomechanical cantilevers, which compete for space with the absorbers and isolation beams, resulting in limited sensitivity. By integrating a designed metalens, large deformation, high thermal isolation, and high effective fill factor can be achieved simultaneously. Several pixel designs of optomechanical uncooled IR focal plane array (FPA) with designed integrated metalens are evaluated and optimized through numerical simulation. High thermal conversion efficiency and thermomechanical sensitivity μm K−1 are simultaneously achieved with an inherent noise-equivalent temperature difference(NETD) value of mK at the preset × pixels. Using Figure of Merit(FOM) as a comprehensive evaluation of NETD and response time, the optimized structure can be improved by up to 40% over the original structure.

Spatial and temporal characteristics of past droughts in New Brunswick (1971–2020)

AbstractThis study aimed to provide a historical picture from 1971 to 2020 of the state of droughts in New Brunswick (NB). More specifically, we wished to determine whether there were statistically significant trends using two drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation‐Evapotranspiration Index (SPEI). Monthly precipitation (rain and snow) and average maximum and minimum temperatures were obtained from 10 stations located in New Brunswick. Then, we applied Mann–Kendall and Sen's Slope's nonparametric tests to these two indices at a 1‐, 3‐, 6‐ and 12‐month timescale. The results have shown that the average value for the SPI and SPEI evolution throughout the study period indicated a decrease in indices values (at 95% confidence level). The temporal evolution of the SPI and SPEI were similar at various timescales regarding severities and intensities. However, there were still slight differences in the fluctuation values, especially during the last 20 years of the study period. At a 12‐month timescale, both indices indicated the driest years as being 2020, 2001 and 2004. The SPEI Miramichi, Saint John and Moncton stations had maximum negative MK values (−0.259, −0.221 and −0.215), respectively. As for spatial distribution, four stations located in the south stood out with the highest increase in dry conditions and significantly negative trends (meaning increased drought in this case). Stations in the northern part of the province (Bathurst and Charlo) show non‐significant trends. This study suggests a slight drought increase trend exists in New Brunswick, while an increase in annual precipitation is expected between 42 and 324 mm by 2100 according to climate scenario RCP8.5 of CMIP6.

Correlation of IVIM/DKI Parameters with Hypoxia Biomarkers in Fibrosarcoma Murine Models: Direct Control of MRI and Pathological Sections

To investigate whether intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) parameters correlate with hypoxia biomarkers, namely hypoxia inducible factor-1ɑ (HIF-1ɑ), carbonic anhydrase IX (CAIX), and pimonidazole (PIMO), in fibrosarcoma (FS) murine models. A model of 30 FS nude mice was established. All mice underwent magnetic resonance imaging (MRI) scans after which the IVIM (standard apparent diffusion coefficient [standard ADC], pure diffusion coefficient [D], pseudo-diffusion coefficient [D*], and perfusion fraction [f]) and DKI parameters (mean diffusion [MD], mean kurtosis [MK]) were obtained. Based on an MRI-pathology controlled method, correlations between each MRI parameter and hypoxia biomarkers were assessed by Pearson or Spearman tests. An independent sample t-test or Wilcoxon's rank sum test, and receiver operating characteristic curves were used to identify whether MRI parameters could differentiate between high and low expressions of hypoxia biomarkers. The IVIM/DKI parameters showed varying degrees of correlation with HIF-1α, CAIX, and PIMO expression. Among them, the D, f, and MK values could confirm HIF-1α expression, while D, f, and MK values could assess CAIX expression. Finally, standard D and MK values could evaluate PIMO expression levels. IVIM and DKI parameters can be used to reflect hypoxic biomarkers of FS and have the potential to detect tumor hypoxia.

Feasibility of diffusion kurtosis imaging in evaluating cervical spinal cord injury in multiple sclerosis.

This research aimed to assess gray matter (GM), white matter (WM), lesions of multiple sclerosis (MS) and the therapeutic effect using diffusion kurtosis imaging (DKI). From January 2018 to October 2019, 78 subjects (48 of MS and 30 of health) perform routine MR scan and DKI of cervical spinal cord. The MS patients were divided into 2 groups according to the presence or absence of T2 hyperintensity. DKI-metrics were measured in the lesions, normal-appearing GM and WM. Significant differences were detected in DKI metrics between MS and healthy (P < .05) and between patients with cervical spinal cord T2-hyperintense and without T2-hyperintense (P < .001). Compared to healthy, GM-mean kurtosis (MK), GM-radial kurtosis, and WM-fractional anisotropy, WM-axial diffusion were statistically reduced in patients without T2-hyperintense (P < .05). Significant differences were observed in DKI metrics between patients with T2-hyperintense after therapy (P < .05), as well as GM-MK and WM-fractional anisotropy, WM-axial diffusion in patients without T2-hyperintense (P < .05); Expanded Disability Status Scale was correlated with MK values, as well as Expanded Disability Status Scale scores and MK values after therapy. Our results indicate that DKI-metrics can detect and quantitatively evaluate the changes in cervical spinal cord micropathological structure.

Based on functional and histopathological correlations: is diffusion kurtosis imaging valuable for noninvasive assessment of renal damage in early-stage of chronic kidney disease?

To evaluate the potential of 3T magnetic resonance diffusion kurtosis imaging (DKI) in assessing the renal damage in early-stage of chronic kidney disease (CKD) patients with normal or slightly changed functional index, using histopathology as reference standard. 49 CKD patients and 18 healthy volunteers were recruited in this study. CKD patients were divided into two groups based on estimated glomerular filtration rate (eGFR): Study group I (eGFR ≥ 90ml/min/1.73m2 [n = 20]) and Study group II (eGFR < 90ml/min/1.73m2 [n = 29]). DKI was performed in all participants. The DKI parameters (mean kurtosis [MK], mean diffusivity [MD], fractional anisotropy [FA]) of renal cortex and medulla were measured. The differences of parenchymal MD, MK and FA values among the different groups were compared. The correlations between DKI parameters and clinicopathological characteristics were assessed. Diagnostic performance of DKI to assess renal damage in early-stage of CKD was analyzed. The cortex MD and MK showed significant difference among three groups (P < 0.05): trend of cortex MD: Study group II < Study group I < control group; trend of cortex MK: control group < Study group I < Study group II. The cortex MD and MK and medulla FA were correlated with eGFR and Interstitial fibrosis/Tubular atrophy score (0.3 < r < 0.5). Cortex MD and MK yielded an AUC of 0.752 for differentiating healthy volunteers from CKD patients with eGFR ≥ 90ml/min/1.73 m2. DKI shows potential in non-invasive and multi-parameter quantitative assessment of renal damage in early-stage of CKD patients and provide additional information for changes in renal function and histopathology.

Diffusion tensor and kurtosis imaging reveal microstructural changes in the trigeminal nerves of patients with trigeminal neuralgia.

To evaluate the use of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) for detection of microstructural changes in the trigeminal nerves of trigeminal neuralgia (TN) patients. Forty TN patients and 40 healthy controls were examined using 3T magnetic resonance imaging (MRI) to evaluate DTI and DKI parameters in trigeminal nerves. One-way ANOVA was used to test the differences in age, sex, and DTI and DKI parameters between the TN-affected sides, TN-unaffected sides, and controls. For parameters with inter-group differences, pairwise comparisons were performed. Then, the difference ratios (DRs) of the parameters with statistical differences were calculated and used for the receiver operating characteristic (ROC) analysis to assess their diagnostic performance. In addition, for the DTI and DKI parameter values with differences, we used pure DTI and DKI values to perform the ROC analysis. Compared to the unaffected sides and controls, the FA, MK, and Kr of the affected sides of TN patients were significantly reduced, while ADC was significantly increased (p < 0.05). The diagnostic efficiency of the FA DRs (AUC: 0.974; cutoff value: 0.038; sensitivity: 100%; specificity: 95.0%) was the highest among all DTI and DKI parameters. The DRs of FA and MK more efficiently diagnosed TN than pure FA and MK values. DTI and DKI allowed detection of microstructural changes in TN-affected trigeminal nerves. FA DR was the best independent predictor of microstructural changes in TN. Both DTI and DKI can be used for noninvasive quantitative evaluation of the changes in the microstructure of the cisternal segment of the cranial nerves in clinical practice. • Diffusion tensor imaging (DTI) can be used to evaluate the in vivo integrity of white matter and nerve fiber pathway. • Diffusion kurtosis imaging (DKI) has been shown to be considerable sensitive to microstructural changes. • DTI combined with DKI can comprehensively evaluate the status of the TN-affected trigeminal nerve.

Preliminary research of the classification of the brain acute stroke lesions by the Diffusion Kurtosis Imaging (DKI) and Diffusion Weighted Imaging (DWI) parameters.

Diffusion-weighted magnetic resonance imaging (DWI) is a mature scanning technique. With high sensitivity in detecting cerebral infractions, it has become an essential part of the clinical evaluation of acute stroke. However, with the update in medical ideals and treatment, clinicians are now focusing on distinguishing between reversible and irreversible brain tissue damage rather than detecting ischaemic lesions alone. We supposed that Diffusion Kurtosis Imaging (DKI) could classify heterogeneous DWI lesions, deepening the understanding of tissue injury. We systematically studied the different parameters of DKI in acute stroke patients in the literature. We collected 41 patients (26 male, 15 female), including different infarctions with acute cerebral infarction in different brain regions. Of all patients, 20 were single-infarction, while others were multi-infarctions. In this paper, we categorized acute cerebral infarction lesions into two types according to the parametric characteristics of both DKI and DWI. Type I means the DKI and DWI were matched, and Type II means the DKI and DWI were mismatched. Based on each parametric map, the region of interest (ROI) is outlined in each most severe lesion area (as large as possible in the center of the lesion). In the control group, ROIs of the same size are located in the corresponding regions of the contralateral hemisphere. In both Type I and Type II, all parameters conform to a normal distribution. An independent sample T-test was used to compare the differences between each group. In Type I, we found the FA, MD, Da, Dr, MK and Ka values were statistically different (P< 0.05), while in Type II, only the MK and Ka values were statistically different (P< 0.05). DKI, compared to DWI, can provide more imaging information about intracranial ischemic infarction, which can deepen the understanding of the mechanism of ischemic tissue damage. Our classification of the brain acute stroke lesions by DKI parameters and DWI may help us rediscover the real core of infraction.

Soft tissue sarcoma: intravoxel incoherent motion and diffusion kurtosis imaging parameters correlate with the histological grade and Ki-67 expression.

Accurate prediction of the histological grade and Ki-67 expression of soft tissue sarcoma (STS) before surgery is essential for the subsequent diagnosis, treatment, and prognostic evaluation of patients. To evaluate intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) in predicting the histological grade and Ki-67 expression of STS. A total of 40 patients underwent 3-T MRI, including conventional sequences; IVIM and DKI parameters were obtained. All patients were divided into a low-grade (grade 1 and grade 2) group and a high-grade (grade 3) group through pathological analysis. Ki-67 expression of each lesion was calculated. Chi-square test, independent sample t-test, Mann-Whitney U test, Pearson, Spearman, and receiver operating characteristic curve analysis were performed. There were 17 patients in the low-grade group and 23 in the high-grade group. Ki-67 expression was in the range of 10%-80%. D value was inversely correlated with Ki-67 expression. MK value showed a moderate positive correlation with Ki-67 expression. Regarding histological grading, only the peritumoral enhancement was statistically different between low- and high-grade STS on conventional MRI (P=0.024). The high-grade group had significantly higher MK value and lower D and MD value than the low-grade group. MK value showed the best diagnostic performance. The combination of MK and MD yielded the highest specificity (88.24%), and the combination of D, MK, and MD yielded the best area under the curve value (0.841) and sensitivity (95.65%). IVIM and DKI parameters were correlated with Ki-67 expression and could help differentiate between low- and high-grade STS.

Preliminary Feasibility Study on Diffusion Kurtosis Imaging to Monitor the Early Functional Alterations of Kidneys in Streptozocin-Induced Diabetic Rats

The aim of this study was to investigate the potential of diffusion kurtosis imaging (DKI) to assess the early renal functional undulation of diabetic mellitus (DM). Fifty-seven Sprague-Dawley (SD) rats were randomly divided into two groups and eventually 48 rats were included in this study: the normal control (CON) group and diabetic mellitus (DM) group. Weeks 0, 4, 8, and 12 after the diabetes model was successfully established, all the rats were scanned on the 3.0T MRI. The DKI derived parameters of renal parenchyma, including fractional anisotropy (FAco, FAme), mean diffusivity (MDco, MDme), and mean kurtosis (MKco, MKme) were measured. Their alteration over time was analyzed and then correlated with urine volume (UV), blood urea nitrogen (BUN), and serum creatinine (Scr) using Pearson correlation analysis. Finally, hematoxylin and eosin (H&E) staining was performed on the kidneys of the two groups. There was a decreasing trend in FA, MK, and MD values over time in diabetic rats. Also, the gradually worsening histological damage of kidneys was noted over time in diabetic rats. The cortical FA and MK values and medullary FA, MK and MD values of diabetic rats were significantly lower than those of controls at most time points after DM induction. In addition, negative correlations were revealed between the BUN and FAco (r=-0.43, p = 0.03) or FAme value (r=-0.49, p = 0.01). The cortical MK value was moderately correlated with UV (r=-0.46, p = 0.03) and BUN (r=-0.55, p = 0.01). The preliminary findings suggest that DKI might be an effective and sensitive tool to assess the early changes of renal function impairment in diabetic rats. The FA values of the cortex and medulla and the MK value of the cortex are sensitive markers in detecting renal injury in diabetic rats.

Diagnostic value of multi-model high-resolution diffusion-weighted MR imaging in breast lesions: Based on simultaneous multi-slice readout-segmented echo-planar imaging

PurposeTo investigate the diagnostic value of multi-model high-resolution diffusion-weighted MR imaging (DWI) in breast lesions, with a comparison of simultaneous multi-slice readout-segmented echo-planar imaging (SMS rs-EPI) and single-shot EPI (ss-EPI). Materials and MethodsThis retrospective study was approved by the institutional ethics committee and included 120 patients with 122 breast lesions (25 benign and 97 malignant). All patients underwent breast DWI with multi-b values (0, 50, 100, 200, 400, 800, 1200, and 2000 s/mm2) based on both SMS rs-EPI and ss-EPI on a 3.0 T MR scanner. Quantitative DWI-derived parameters including ADC, MK, MD, D, D*, and f were calculated based on mono-exponential (Mono), intravoxel incoherent motion (IVIM), diffusion kurtosis (DKI) models. Meanwhile, both DWI sequences were qualitatively evaluated with respect to overall image quality, lesion conspicuity, image artifact, geometric distortion, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and lesion contrast. The differences in DW-derived parameters, image quality, and diagnostic performance were statistically compared between SMS rs-EPI and ss-EPI groups. ResultsThe SMS rs-EPI produced higher Contrast, CNR and lower SNR than ss-EPI (p < 0.01). The image quality of SMS rs-EPI was superior to ss-EPI either in subjective or objective evaluation. There was no significant difference between the SMS rs-EPI and ss-EPI for either MD or the D* (p > 0.05). However, the MK and f between the two sequences showed significant differences (p < 0.05). Spearman’s correlation coefficient displayed good linear correlation for MK values (r = 0.73, 95% CI 0.617–0.857), MD values (r = 0.88, 95% CI 0.814–0.926), ADC values (r = 0.93, 95% CI 0.869–0.948) and D values (r = 0.93, 95% CI 0.856–0.948) between SMS rs-EPI and ss-EPI. Spearman’s correlation coefficient for f values (r = 0.25, 95% CI 0.226–0.559) and D* values (r = 0.22, 95% CI 0.025–0.348) were fair and no correlation between the two sequences. MK values have the highest diagnostic value in differentiating benign and malignant breast lesions. ConclusionsHigh-resolution multi-model DWI based on SMS rs-EPI technique can provide superior image quality and lesion characterization, with comparable diagnostic performance as compared with ss-EPI DWI in differentiating benign and malignant breast lesions. Of different DWI-derived parameters, MK values showed the best diagnostic performance.

Three-dimensional arterial spin labeling and diffusion kurtosis imaging in evaluating perfusion and infarct area size in acute cerebral ischemia.

BACKGROUNDEarly thrombolytic therapy is crucial to treat acute cerebral infarction, especially since the onset of thrombolytic therapy takes 1-6 h. Therefore, early diagnosis and evaluation of cerebral infarction is important.AIMTo investigate the diagnostic value of magnetic resonance multi-delay three-dimensional arterial spin labeling (3DASL) and diffusion kurtosis imaging (DKI) in evaluating the perfusion and infarct area size in patients with acute cerebral ischemia.METHODSEighty-four patients who experienced acute cerebral ischemia from March 2019 to February 2021 were included. All patients in the acute stage underwent magnetic resonance-based examination, and the data were processed by the system’s own software. The apparent diffusion coefficient (ADC), average diffusion coefficient (MD), axial diffusion (AD), radial diffusion (RD), average kurtosis (MK), radial kurtosis (fairly RK), axial kurtosis (AK), and perfusion parameters post-labeling delays (PLD) in the focal area and its corresponding area were compared. The correlation between the lesion area of cerebral infarction under MK and MD and T2-weighted imaging (T2WI) was analyzed.RESULTSThe DKI parameters of focal and control areas in the study subjects were compared. The ADC, MD, AD, and RD values in the lesion area were significantly lower than those in the control area. The MK, RK, and AK values in the lesion area were significantly higher than those in the control area. The MK/MD value in the infarct lesions was used to determine the matching situation. MK/MD < 5 mm was considered matching and MK/MD ≥ 5 mm was considered mismatching. PLD1.5s and PLD2.5s perfusion parameters in the central, peripheral, and control areas of the infarct lesions in MK/MD-matched and -unmatched patients were not significantly different. PLD1.5s and PLD2.5s perfusion parameter values in the central area of the infarct lesions in MK/MD-matched and -unmatched patients were significantly lower than those in peripheral and control areas. The MK and MD maps showed a lesion area of 20.08 ± 5.74 cm2 and 22.09 ± 5.58 cm2, respectively. T2WI showed a lesion area of 19.76 ± 5.02 cm2. There were no significant differences in the cerebral infarction lesion areas measured using the three methods. MK, MD, and T2WI showed a good correlation.CONCLUSIONDKI parameters showed significant difference between the focal and control areas in patients with acute ischemic cerebral infarction. 3DASL can effectively determine the changes in perfusion levels in the lesion area. There was a high correlation between the area of the infarct lesions diagnosed by DKI and T2WI.

Multiparameter Magnetic Resonance Quantitative Evaluation of Pancreatic Cancer with Vascular Invasion.

Objective To analyze the value of multiparameter magnetic resonance (mpMRI) in the diagnosis of pancreatic cancer with vascular invasion from two aspects: morphology and function, so as to provide a reliable diagnostic basis for preparing the clinical treatment plans. Methods Totally 31 case data of pancreatic cancer patients diagnosed in our hospital from January 2020 to March 2021 were enrolled in this study. All patients underwent multiparameter magnetic resonance imaging (T1WI, T2WI, DKI, and DCE-MRI) before surgery, and then all patients underwent pancreatic cancer surgery. Two experienced radiologists analyzed these obtained images according to the image reports and combined them with the pathological results. Taking pathological results as gold standard, the sensitivity, specificity, and accuracy of quantitative parameters derived from T2WI, DKI, DCE, T2WI + DKI, T2WI + DCE, and T2WI + DKI + DCE for the diagnostic capabilities of pancreatic cancer vascular invasion were calculated using diagnostic laboratory methods. Kappa consistency test was used to estimate the consistency of two radiologists' diagnosis and analysis. The images obtained by DKI sequence were input into the postprocessing software MITK-Diffusion v2014.10.02, The images obtained from DCE sequence were processed by the Tissue 4D software on the Siemens syngo via workstation to calculate and analyze each tumor ROI's MD, MK values from DKI, and Ktrans, Kep, Ve values from DCE. Independent samples t-test was used to compare the parameters of pancreatic cancer with vascular invasion group (16 cases) and nonvascular invasion group (15 cases). ROC curve was used to analyze the efficacy of each parameter in diagnosing pancreatic cancer vascular invasion. Results The sensitivity, specificity, and accuracy of T2WI were 62.5%, 53.5%, and 58.1%; those of DKI were 56.3%, 60.0%, and 58.1%; those of DCE were 68.8%, 60.0%, and 64.5%; those of T2WI + DKI were 68.8%, 66.7%, and 67.7%; those of T2WI + DCE were 75.0%, 66.7%, and 71.1%; those of T2WI + DKI + DCE were 81.2%, 73.3%, and 77.4%, respectively. These two diagnostic radiologists analyzed image data with good consistency, Kappa = 0.834. MD, MK, Ktrans, Kep, and Ve were significantly different between the vascular invasion group and the nonvascular invasion group (p < 0.05). Each parameter's AUC of ROC curve was 0.773, 0.829, 0.794, 0.802, and 0.846 (p < 0.05). Take MD = 2.285 × 10−3 mm/s2, MK = 0.72, Ktrans = 0.103, Kep = 0.337, and Ve = 0.353 as thresholds; the sensitivity of these parameters to diagnose vascular invasion of pancreatic cancer was 73.33%, 75%, 87.5%, 68.8%, and 68.8%. The specificity of them was 75%, 80%, 60%, 86.7%, and 86.7%, respectively. Conclusion The combined analysis of T2WI + DKI + DCE can improve the specificity and accuracy of diagnostic efficiency of vascular invasion of pancreatic cancer and provide an important diagnostic basis for pancreatic cancer's preoperative treatment.

On Some Generalizations of the Property B Problem of an n-Uniform Hypergraph

The extremal problem of hypergraph colorings related to the Erdős–Hajnal property B-problem is considered. Let k be a natural number. The problem is to find the value of mk(n) equal to the minimal number of edges in an n-uniform hypergraph that does not admit 2-colorings of the vertex set such that every edge of the hypergraph contains at least k vertices of each color. In this paper, we obtain new lower bounds for mk(n).

Prediction of Prognostic Factors and Genotypes in Patients With Breast Cancer Using Multiple Mathematical Models of MR Diffusion Imaging.

PurposeTo explore the clinical value of apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM), and diffusion kurtosis imaging (DKI) based on diffusion-weighted MRI (DW-MRI) for predicting genotypes and prognostic factors of breast cancer.Materials and MethodsA total of 227 patients with breast cancer confirmed by pathology were reviewed retrospectively. Diffusion-weighted imaging (DWI), IVIM, and DKI were performed in all patients. The corresponding ADC, true diffusion coefficient (D), perfusion-related diffusion coefficient (D*), perfusion fraction (f), mean diffusion rate (MD), and mean kurtosis value (MK) were measured. Multivariate logistic regression analysis and receiver operating characteristic (ROC) curve were used to analyze the diagnostic efficacy in predicting the Nottingham prognostic index (NPI), the expression of antigen Ki-67, and the molecular subtypes of breast cancer. The nomogram of the combined genotype-prediction model was established based on the multivariate logistic regression model results.ResultsD* and MK values were significantly higher in the high-grade Nottingham group (NPI ≥ 3.4) than the low-grade Nottingham group (NPI < 3.4) (p < 0.01). When D* ≥ 30.95 × 10−3 mm2/s and MK ≥ 0.69, the NPI tended to be high grade (with areas under the curve (AUCs) of 0.712 and 0.647, respectively). The combination of D* and MK demonstrated the highest AUC of 0.734 in grading NPI with sensitivity and accuracy of 71.7% and 77.1%, respectively. Additionally, higher D*, f, and MK and lower ADC and D values were observed in the high Ki-67 than low Ki-67 expression groups (p < 0.05). The AUC of the combined model (D + D* + f + MK) was 0.755, being significantly higher than that of single parameters (Z = 2.770~3.244, p = 0.001~0.006) in distinguishing high from low Ki-67 expression. D* and f values in the Luminal A subtype were significantly lower than in other subtypes (p < 0.05). Luminal B showed decreased D value compared with other subtypes (p < 0.05). The HER-2-positive subtype demonstrated increased ADC values compared with the Luminal B subtype (p < 0.05). Luminal A/B showed significantly lower D, D*, MD, and MK than the non-Luminal subtypes (p < 0.05). The combined model (D + D* + MD + MK) showed an AUC of 0.830 in diagnosing the Luminal and non-Luminal subtypes, which is significantly higher than that of a single parameter (Z = 3.273~4.440, p < 0.01). f ≥ 54.30% [odds ratio (OR) = 1.038, p < 0.001] and MK ≥ 0.68 (OR = 24.745, p = 0.012) were found to be significant predictors of triple-negative subtypes. The combination of f and MK values demonstrated superior diagnostic performance with AUC, sensitivity, specificity, and accuracy of 0.756, 67.5%, 77.5%, and 82.4%, respectively. Moreover, as shown in the calibration curve, strong agreements were observed between nomogram prediction probability and actual findings in the prediction of genotypes (p = 0.22, 0.74).ConclusionDWI, IVIM, and DKI, as MR diffusion imaging techniques with different mathematical models showed potential to identify the prognosis and genotype of breast cancer. In addition, the combination of these three models can improve the diagnostic efficiency and thus may contribute to opting for an appropriate therapeutic approach in clinic treatment.

Characterization of Clinical Symptoms of Cervical Spondylotic Myelopathy Based on DKI Imaging Parameter Ratios.

In recent years, people's living conditions have significantly improved, and their lifestyles have been diversified. However, the incidence of various diseases has also increased with it, including cervical spondylotic myelopathy (CSM). Spinal cord cervical spondylosis is one of the spinal cord compression disorders that can be severely disabling and accounts for 10% to 15% of all cervical spondylosis. In this paper, DKI image processing technology is used to study the symptoms of cervical spondylosis, which is helpful to help them explore the symptoms and causes. The onset of cervical spondylosis has a longer period of time, and the period of conservative treatment will inevitably require a longer period of time. The clinical symptoms of cervical spinal cord compression are mainly pain, and after the cervical spinal cord nerve is compressed, ischemia and hypoxia will occur, the nerve sensitivity will increase, and the patient will have reflex neck muscle pain symptoms. This causes degeneration of the patient's intervertebral disc tissue, degeneration of facet joints, ossification of the posterior longitudinal ligament, and formation of spurs on the posterior edge of the vertebral body. The condition will become more complicated, so it is very important to identify the characteristics of the clinical symptoms of cervical spondylotic myelopathy to help patients with cervical spondylosis recover. This paper identifies the clinical symptoms of cervical spondylosis based on the parameter ratio method of Diffusional Kurtosis Imaging (DKI). The current state of diffusion kurtosis imaging and the treatment of cervical spondylosis and the treatment operation are introduced, and the image enhancement technology in medical imaging is used to analyze the disc herniation of each segment in the overflexion, neutral and hyperextension positions. After comparing the FA, MK, and MD values in the spinal cord between the normal group and the patient group, the results showed that the FA, MD and MK values in the patient group were lower than those in the normal group, and the findings showed that the MD and MK values were positively correlated with the JOA score, reflecting that as the clinical symptoms of spinal cervical spondylosis worsened. The size and number of cervical intervertebral disc bulge on the hyperextension image is obvious and the number increases (especially the C4/5, C5/6, and C6/7 intervertebral discs with greater mobility), and the highest is 0.82 and 27%, respectively.

Application of Diffusion Weighted Imaging Techniques for Differentiating Benign and Malignant Breast Lesions.

To explore the value of apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM), and diffusional kurtosis imaging (DKI) based on diffusion weighted magnetic resonance imaging (DW-MRI) in differentiating benign and malignant breast lesions. A total of 215 patients with breast lesions were prospectively collected for breast MR examination. Single exponential, IVIM, and DKI models were calculated using a series of b values. Parameters including ADC, perfusion fraction (f), tissue diffusion coefficient (D), perfusion-related incoherent microcirculation (D*), average kurtosis (MK), and average diffusivity (MD) were compared between benign and malignant lesions. ROC curves were used to analyze the optimal diagnostic threshold of each parameter, and to evaluate the diagnostic efficacy of single and combined parameters. ADC, D, MK, and MD values were significantly different between benign and malignant breast lesions (P<0.001). Among the single parameters, ADC had the highest diagnostic efficiency (sensitivity 91.45%, specificity 82.54%, accuracy 88.84%, AUC 0.915) and the best diagnostic threshold (0.983 μm2/ms). The combination of ADC and MK offered high diagnostic performance (sensitivity 90.79%, specificity 85.71%, accuracy 89.30%, AUC 0.923), but no statistically significant difference in diagnostic performance as compared with single-parameter ADC (P=0.268). The ADC, D, MK, and MD parameters have high diagnostic value in differentiating benign and malignant breast lesions, and of these individual parameters the ADC has the best diagnostic performance. Therefore, our study revealed that the use of ADC alone should be useful for differentiating between benign and malignant breast lesions, whereas the combination of MK and ADC might improve the diagnostic performance to some extent.

Value of multiple models of diffusion-weighted imaging for improving the nodal staging of preoperatively node-negative rectal cancer.

To investigate the parameters of multiple diffusion-weighted imaging (DWI) models for improving nodal staging of preoperatively node-negative rectal cancer. A total of 74 rectal cancer patients without suspected metastatic lymph nodes on conventional MRI who underwent direct surgical resection between November 2018 and January 2020 were enrolled in this prospective study. DWI parameters of mono-exponential model (ADC), intravoxel incoherent motion (D, D* and f), stretched exponential model (DDC and α), and diffusion kurtosis imaging (MD and MK) within the whole tumor were measured to predict the nodal staging in rectal cancer patients. The D*, DDC, and MK values were significantly different in patients with pN0 and pN1-2 (all P < 0.001). The D*, DDC, and MK showed good diagnostic performance with the area under the receiver operating characteristic (AUC) of 0.788, 0.827 and 0.799. Multivariate analysis indicated D* (odds ratio, OR = 1.163, P = 0.003) and DDC (OR = 0.007, P = 0.019) as significant predictors of nodal staging. The combination of DDC and D* demonstrated superior diagnostic performance with the AUC, sensitivity, specificity and accuracy of 0.872, 0.800, 0.932 and 0.878, respectively. Multiple functional DWI parameters were potential to identify the rectal cancer patients with micro-nodal involvement for accurate treatment.