Preliminary Study On The Evaluation Of Pulmonary Occupying Lesions By Free Breathing Magnetic Resonance Imaging Sequences

Part Ⅰ Evaluation of morphology of pulmonary occupying lesions by three kinds of free breathing magnetic resonance imaging sequencesObjective:According to the standard of CT images,the morphological characteristics of pulmonary lesions collected and displayed by Star-VIBE,GRASP-VIBE and 3D-SPACE free breathing MRI sequences were evaluated,and the effectiveness of these three sequences in the display and imaging evaluation of this kind of lesions was discussed.Materials and methods:Patients with lung space occupying lesions who met the inclusion criteria were prospectively collected and underwent plain chest CT scan and MR scanning of the above three free respiratory sequences.At first,the two imaging doctors scored the image quality of MR independently.Then,in the case of unknown pathological results,the morphological signs of each space occupying lesion on CT and MR images were evaluated and recorded independently:maximum diameter of lesion,speculation,lobulation,cavitation,bubblelike attenuation,pleural indentation and lymph node enlargement in the hilar or mediastinum.The subjective scores of the two doctors were analyzed by Kappa test.The image quality scores of the three sequences were compared by Kruskal-Wallis H test.If there is any difference,the paired Wilcoxon symbolic rank test is used for further pairwise comparison.The image quality scores of the three sequences were compared by Kruskal-WallisH test.If there is any difference,the paired Wilcoxon symbolic rank test is used for further pairwise comparison.Using the subject working characteristic curve(ROC),as the standard,the sensitivity and specificity of the three sequences of images in showing the morphological signs of pulmonary space occupying lesions were compared,and the area under the ROC curve(AUC)was calculated.Results:Forty-nine patients were included in this study.Of the 49 space occupants,41 were lung cancer(9 cases of squamous cell carcinoma,27 cases of adenocarcinoma and 5 cases of small cell carcinoma),and the other 8 were benign lesions(4 cases of pulmonary tuberculosis and 4 cases of inflammation).The two imaging doctors showed good consistency in the scores of MR image quality and the morphological signs of the lesions on CT and MR images(Kappa values are 0.84-1.00,p<0.05).There were significant differences in image quality scores among the three free respiratory sequences.The score of edge and artifact(less artifact)in GRASP-VIBE sequence was higher than that in Star-VIBE sequence,and the latter was higher than that in 3D-SPACE sequence.In the overall image quality score,GRASP-VIBE sequence was higher than Star-VIBE and 3D-SPACE sequence,but there was no significant difference between the latter two sequences.There was no significant difference in the maximum diameter of lung space occupying foci between the three MR sequences and CT images.Compared with CT images,burr sign and lymph node enlargement sign showed well in GRASP-VIBE sequence,but not in the other two sequences.The display of lobulation sign,cavity or vacuole sign was better in the three free respiratory sequences,and the display effect was GRASP-VIBE,STAR-VIBE and 3D-SPACE from good to poor.Pleural indentation sign showed well in 3D-SPACE sequence,but not in the other two sequences.Conclusion:Three free respiratory magnetic resonance imaging sequences,Star-VIBE,GRASP-VIBE and 3D-SPACE,have their own advantages in showing different morphological features of pulmonary space-occupying lesions.Combined with multi-sequence parameters,multi-directional observation,free respiratory magnetic resonance imaging sequence can be used as a potential supplementary means to observe the morphological characteristics of lung space-occupying lesions.Especially for patients who are unable to cooperate with respiratory patients and radiation-sensitive people,magnetic resonance free respiratory sequence has a broad application prospect.Part Ⅱ Evaluation of blood perfusion of pulmonary lesions by DCE-MRI with free breathing GRAPP-VIBE sequenceObjective:Quantitative analyze the blood perfusion of pulmonary space occupying lesions by DCE-MRI of free respiration GRASP-VIBE sequence,and to compare the differences of quantitative perfusion parameters between different histological sources and different pathological stages(contrast enhancement,CE)-CT images were compared to explore the application value of MR technique in functional imaging evaluation of pulmonary occupying lesionsMaterials and methods:The patients with pulmonary space occupying lesions who met the inclusion criteria were prospectively collected and DCE-MRI of chest CT plain scan,enhanced scan and free respiration GRASP-VIBE sequence were performed successively.In the absence of pathological results,The region of interest(region of interest,ROI)was delineated by an imaging physician with experience in the diagnosis of chest disease in the parenchyma of the lesion on CT images and avoiding necrosis,calcification,bleeding and cystic change in the lesion.The net increment of CT enhancement is calculated and measured.The original DCE-MRI images were input into OmniKinetics(GEHealthcare)full quantitative post-processing workstation,and the Extended Tofts Linear two-compartment model of drug hemodynamics was used for perfusion analysis.The following quantitative parameter diagrams were obtained:volume transfer constant(Kfrans),reflux rate constant(Kep),extracellular volume fraction(Ve)and area under concentration-time curve(iAUC).Referring to the position and size of the ROI drawn on the CT image,draw the corresponding ROI,on these parameter diagrams and extract the parameter values.First of all,the correlation between the Ktrans value,Kep value,Ve value,IAUC value and the net increment value of CT enhancement was analyzed.Then grouped according to the following methods,and according to the number of groups and the type of data distribution,single factor variance analysis(ANOVA),unpaired t test were used to compare the differences of the above parameters between groups in turn:①All selected patients were divided into lung cancer group,tuberculosis group and inflammation group②All patients with lung cancer were divided into lung squamous cell carcinoma group,lung adenocarcinoma group and small cell lung cancer group.③All patients with lung cancer were divided into large lung cancer group with maximum diameter>3cm and small lung cancer group with maximum diameter ≤3cm.④All patients with lung cancer were divided into metastasis positive group and metastasis negative group according to whether there was mediastinum or hilar lymph node short diameter≥1cm.Results:Forty-three patients were included in this study,including 35 cases of lung cancer(9 cases of squamous cell carcinoma,21 cases of adenocarcinoma,5 cases of small cell lung cancer),4 cases of tuberculosis and 4 cases of inflammation.Of the 35 lung cancer foci,21 were large lung cancer and 14 were small lung cancer.Lymph node metastasis was positive in 22 cases and negative in 13 cases.The value,Ve value and iAUC value extracted from all lesions were significantly positively correlated with the net enhancement of CT enhancement(r=0.448,p<0.05;r=0.623,p<0.001;r=0.545,p<0.001),but there was no significant correlation between Kep value and CT enhanced net increment(r=0.213,p>0.05).Group①The Ktrans value,Ve value and iAUC value in the inflammatory group were significantly higher than those in the lung cancer group(p<0.05),but there was no significant difference between the inflammatory group and the lung cancer group(p>0.05).In addition,the Kfrans value,Ve value,Kep value and iAUC value in the lung cancer group were significantly higher than those in the tuberculosis group(p<0.05).There was no significant difference in quantitative perfusion parameters between groups②,③and④(p>0.05).Conclusion:It is feasible to evaluate the blood perfusion of pulmonary occupying lesions by DCE-MRI of free breathing GRASP-VIBE sequence。This technique not only has the advantages of high spatial resolution and high temporal resolution,but also the quantitative perfusion parameters obtained are the same as CE-CT,which can better reflect the hemodynamic characteristics of the lesion.This can provide a certain reference value for the differentiation of solid components such as pulmonary inflammation,lung cancer and tuberculosis.