Radiomics models based on non-enhanced MRI can differentiate chondrosarcoma from enchondroma / 南方医科大学学报

OBJECTIVE@#To develop and validate radiomics models based on non-enhanced magnetic resonance (MR) imaging for differentiating chondrosarcoma from enchondroma.@*METHODS@#We retrospectively evaluated a total of 68 patients (including 27 with chondrosarcoma and 41 with enchondroma), who were randomly divided into training group (=46) and validation group (=22). Radiomics features were extracted from TWI and TWI-FS sequences of the whole tumor by two radiologists independently and selected by Low Variance, Univariate feature selection, and least absolute shrinkage and selection operator (LASSO). Radiomics models were constructed by multivariate logistic regression analysis based on the features from TWI and TWI-FS sequences. The receiver-operating characteristics (ROC) curve and intraclass correlation coefficient (ICC) analyses of the radiomics models and conventional MR imaging were performed to determine their diagnostic accuracy.@*RESULTS@#The ICC value for interreader agreement of the radiomics features ranged from 0.779 to 0.923, which indicated good agreement. Ten and 11 features were selected from the TWI and TWI-FS sequences to construct radiomics models, respectively. The areas under the curve (AUCs) of TWI and TWI-FS models were 0.990 and 0.925 in training group and 0.915 and 0.855 in the validation group, respectively, showing no significant differences between the two sequence-based models (>0.05). In all the cases, the AUCs of the two radiomics models based on TWI and TWI-FS sequences and conventional MR imaging were 0.955, 0.901 and 0.569, respectively, demonstrating a significantly higher diagnostic accuracy of the two sequence-based radiomics models than conventional MR imaging (<0.01).@*CONCLUSIONS@#The radiomics models based on TWI and TWI-FS non-enhanced MR imaging can be used for the differentiation of chondrosarcoma from enchondroma.

Accelerated Time-of-Flight Magnetic Resonance Angiography with Sparse Undersampling and Iterative Reconstruction for the Evaluation of Intracranial Arteries

OBJECTIVE: To compare the image quality of three-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) with sparse undersampling and iterative reconstruction (sparse TOF) with that of conventional TOF MRA. MATERIALS AND METHODS: This study included 56 patients who had undergone sparse TOF MRA for intracranial artery evaluation on a 3T MR scanner. Conventional TOF MRA scans were also acquired from 29 patients with matched acquisition times and another 27 patients with matched scanning parameters. The image quality was scored using a five-point scale based on the delineation of arterial vessel segments, artifacts, overall vessel visualization, and overall image quality by two radiologists independently, and the data were analyzed using the non-parametric Wilcoxon signed-rank test. Contrast ratios (CRs) of vessels were compared using the paired t test. Interobserver agreement was calculated using the kappa test. RESULTS: Compared with conventional TOF at the same spatial resolution, sparse TOF with an acceleration factor of 3.5 could reduce acquisition time by 40% and showed comparable image quality. In addition, when compared with conventional TOF with the same acquisition time, sparse TOF with an acceleration factor of 5 could also achieve higher spatial resolution, better delineation of vessel segments, fewer artifacts, higher image quality, and a higher CR (p < 0.05). Good-to-excellent interobserver agreement (κ: 0.65–1.00) was obtained between the two radiologists. CONCLUSION: Compared with conventional TOF, sparse TOF can achieve equivalent image quality in a reduced duration. Furthermore, using the same acquisition time, sparse TOF could improve the delineation of vessels and decrease image artifacts.

Correlation research of renal perfusion and diffusion function using MRI in renal allograft early after renal transplantation / 中华放射学杂志

Objective To explore the correlationships between microperfusion diffusion indexes derived from intravoxel incoherent motion(IVIM)and perfusion values measured by arterial spin labeling (ASL)in renal allograft. Methods A total of 76 renal allograft recipients and 26 age-matched volunteers (group 0)were included in this prospective study. All subjects were underwent conventional MRI, IVIM and ASL MRI which were performed in the oblique-sagittal plane. Seventy-six recipients were divided into two groups based on the estimated glomerular filtration rate(eGFR):recipients with good allograft function(group 1, eGFR≥ 60 ml · min-1 · 1.73m-2,n=44)and recipients with impaired allograft function(group 2, eGFR0.05), but RBF value was significantly lower(P<0.05). The ADCslow, ADCfast, PF and RBF values of renal cortex were significantly lower in allografts with impaired function compared to allografts with good function(all P<0.01). In renal allografts, there were significant positive correlations between cortical ADCslow, ADCfast, PF, RBF value and eGFR(r values were 0.604, 0.552, 0.579 and 0.673, all P<0.01). Cortical ADCfast and PF value exhibited a significant correlation with RBF for recipients(r values were 0.501 and 0.423, all P<0.01). Conclusion Cortical ADCfast and PF values derived from IVIM and RBF measured by ASL show a significant positive correlation in renal allografts.

Assessment of renal cortex blood flow with arterial spin labeling MRI in patients with type 2 diabetes / 中国医学影像技术

Objective To investigate the value of arterial spin labeling (ASL) MRI in evaluation of renal cortex perfusion in patients with type 2 diabetes.Methods Fifty patients with type 2 diabetes were enrolled and divided into simple diabetes (SD) group (n=25) and diabetes kidney disease (DKD) group (n=25) according to suffering from DKD or not.Based on estimated glomerular filtration rate (eGFR),DKD group were further divided into mild disease subgroup (n=11,eGFR≥ 60 ml/[min · 1.73m2]) and moderate-severe disease subgroup (n=14,eGFR＜60 ml/[min · 1.73m2]).Twenty-five healthy volunteers were recruited as control group at the same time.ASL MRI were performed on all participants.The cortical renal blood flow (RBF) of bilateral kidneys were measured by 2 radiologists.The consistency between 2 radiologists was analyzed.Statistical analysis were conducted to analysis the differences in cortical RBF among different groups.Correlation analysis were performed to evaluate the relationship between RBF and eGFR in type 2 diabetes patients.Results Cortical RBF values measured by two radiologists showed high consistency (all ICC＞0.90).There was significant difference in cortical RBF among control group ([269.71±33.28]ml/[100 g · min]),SD group ([258.52±42.30]ml/[100 g · min]),mild disease group ([242.86±56.86]ml/[100 g · min]) and moderate-severe disease group ([173.39±27.16]ml/ [100 g· min];F=20.66,P＜0.01).Moreover,the RBF in moderate-severe disease group was significantly lower than those in other groups (all P＜0.01).And no significant differences of RBF was found among the remainder groups (P=0.064,0.320).RBF in type 2 diabetes patients was positively correlated to eGFR (r=0.646,P＜0.001).Conclusion ASL MRI is a valuable tool to quantitatively assess the renal perfusion in patients with type 2 diabetes mellitus,which can provide potential imaging indicator as RBF for the functional evaluation of kidney.

Feasibility study of dynamic contrast enhanced magnetic resonance imaging qualita-tive diagnosis of musculoskeletal tumors / 北京大学学报(医学版)

Objective:To investigate the feasibility of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)parameters in differentiating musculoskeletal tumors with different behaviours of pathological findings before therapy.Methods:A total of 34 subjects of musculoskeletal tumors were in-volved in this retrospective analysis.DCE-MRI was performed using a fat-saturated 3 D VIBE (volumetric interpolated breath-hold exam)imaging sequence with following parameters:FA,10 degree;TR/TE, 5.6/2.4 ms;slice thickness,4.0 mm with no intersection gap;field of view,310 mm ×213 mm;ma-trix,256 ×178;voxel size,1 .2 mm ×1 .2 mm ×4.0 mm;parallel imaging acceleration factor.The ac-tuation time for the DCE-MRI sequence was 255 s with a temporal resolution of 5 s and 40 image vo-lumes.Using pathological results as a gold standard,tumors were divided into benign,borderline and malignant tumors.Toft’s model was used for calculation of Ktrans (volume transfer constant),Ve (extra-vascular extracellular space distribute volume per unit tissue volume)and Kep(microvascular permeability reflux constant).Those parameters were compared between the lesions and the control tissues using paired t-tests.The one-way analysis of variance was used to assess the difference among benign,border-line and malignant tumors.P values 0.05 ).Conclusion:DCE-MRI technique is useful to evaluate the pathological behaviour of musculoske-letal tumors.The quantitative analysis of DCE parameters in conjunction with conventional MR images can improve the accuracy of musculoskeletal tumor qualitative analysis.