| Objective: To investigate the difference of signal intensity in diffusion-weighted magnetic resonance(MR)imaging between central lung carcinoma and obstructive atelectasis,and differential efficacy of apparent diffusion coefficient(ADC)different b value for both.Methods: 57 cases(40 males,16 females;age range,40 ~ 80 years;mean age,61years),which had diagnosed to be central lung carcinoma with obstructive atelectasis and treated in our hospital from May 2013 to May 2014,were collected.All the cases were diagnosed by bronchoscopy for lung carcinoma(34 cases of squamous cell carcinoma,14 cases of adenocarcioma cell carcinoma,6 cases of small cell carcinoma,3 cases were unknown pathologically and had diagnosed lung carcinoma according to clinical and image findings).With patients' consent,57 patients were given Siemens1.5T superconductive MRI scan in our department.Standard T1 WI and T2 WI axial scanning,with parameters as TR(repetition time)/TE(echo time)=3740ms/80 ms,FOV(field of view)=300mm×400mm,matrix=384×207,slice thickness= 6mm,layer spacing=1mm.Diffusion-weighted imaging(DWI)axial scanning with a diffusion sensitive factor b value at 200,500,800 s/mm~2,and parameters as TR/TE=2800ms/70 ms,NEX=4,BW(band width)=1500,FOV=300mm×430mm,matrix=128×128,slice thickness= 3mm,layer spacing=1mm.Patients were asked to be at supine position and in eupnea.T1 WI,T2WI,and DWI axial images at varied b value were obtained by respiratory navigation technology.Two diagnostician with more than 10 years experience were asked to jointly read these MRI images,not informed of patients' pathological types.They first compared the signal intensity differences in T1 WI,T2WI images of lung carcinoma and of atelectasis,then compared signal intensity differences on ADC images generated automatically by Siemens Synogo workstation and on DWI images under varied b value.Different DWI signal intensity under different b value was measured,and corresponding ADC values were calculated.ADC values of lung carcinoma and of atelectasis under different b value were compared,and by using ROC curve to find out the cutoff ADC value under a b value for differentiating central lung carcinoma from atelectasis,and the specificity and sensitivity of differential diagnosis for both.Results: Signal intensity contrast in T1 WI image of lung carcinoma and atelectasis was too poor to differentiate them.Resolution of T2 WI image was much higher than that of T1 WI,and the signal intensity of lung carcinoma in T2 WI image was lower than that on atelectasis T2 WI image.In 57 cases,25 cases were distinguished by this.In DWI images,differences of signal identity of central lung carcinoma and atelectasis was more prominent,and signal boundary between both was clearer.In ADC images,which generated automatically by workstation,lung carcinoma images showed a slightly lower signal,while atelectasis showed equal or slightly higher signal.Through this comparison,we distinguished 44 cases in 57 cases.As the b value increased,ADC values of lung carcinoma and atelectasis decreased gradually.At each b value,ADC values of central lung carcinoma was lower than that of atelectasis.When b value was taken at 200 s / mm~2,500 s / mm~2,800 s / mm~2 respectively,area under the curve was0.7565,0.8769 and 0.8279 respectively.This shows that the b value at 800 s / mm~2 has the highest diagnostic efficacy.The cutoff ADC value was 1.46×10-3mm~2/ s,and the sensitivity and specificity in differential diagnosis of central lung carcinoma with atelectasis were 77.2% and 71.9%.atelectasis.DWI shows high sensitivity and specificity in differentiating central lung carcinoma and atelectasis.At each b(b=200 s/mm~2,500 s/mm~2,800 s/mm~2)value,ADC values of central lung carcinoma cases are lower than that of atelectasis.when b value is 800 s / mm~2,the area under ROC is biggest,and the diagnostic efficacy is the highest,and the cutoff ADC value of both cases is 1.46×10-3mm~2/ s.Conclusion: T2 WI is valuable to differential diagnosis of central lung carcinoma andPart ? Diagnostic efficacy of apparent diffusion coefficient of different b value in diagnosing different pathological types of lung lesionsObjective: To analyze ADC differences in different lung pathological type lesions in DWI images and explore the differential diagnostic efficacy of ADC values at varied b(b=200 s/mm~2,500 s/mm~2,800 s/mm~2)values.Methods: 62 lung lesions cases(38 males,24 females;age range,40-80 years;mean age,61 ages),which were diagnosed after CT examination,were collected in our hospital from May 2013 to May 2014.All pathology results obtained by bronchoscopy,lung biopsy or patient follow-up.In these cases,6 are of small cell lung carcinoma,11 of squamous cell carcinoma,8 of well-differentiated adenocarcinoma,13 of poorly differentiated adenocarcinoma and 24 cases of benign lesions(8 cases of inflammatory,5cases of atelectasis,4 cases of TB ball,2 cases of sarcoidosis,2 cases of hamartoma,2cases of adenoma,1 case of transparent cell tumor).With patients' consent,all 62 patients were given Siemens 1.5T superconductive MRI scan in our department.Standard T1 WI and T2 WI axial scanning,with parameters as TR/TE=3740ms/80 ms,FOV=300mm×400mm,matrix=384×207,slice thickness= 6mm,layer spacing=1mm.Diffusion-weighted imaging(DWI)axial scanning with a diffusion sensitive factor b values at 200,500,800s/mm~2,and parameters as TR/TE=2800ms/70 ms,NEX=4,BW=1500,FOV=300mm×430mm,matrix=128×128,slice thickness= 3mm,layer spacing=1mm.Patients were asked to be at supine position and in eupnea.T1 WI,T2WI,and DWI axial images at varied b values were obtained by respiratory navigation technology.Measuring the signal intensity of different lung lesions in DWI images at varied b values on the same level,then using certain formula to calculate corresponding ADC values and note them down.Respectively to compare ADC values differences of different lung lesions at the same b values.To compare diagnostic efficacy of ADC values at different b values for different lesions.To compare ADC differences at varied b values in different lung pathological types and with varying degrees of differentiation of lung lesions.By using ROC curve to compare diagnostic efficacy of pulmonary malignant tumor and benign masses at varied b values,and find out the best cutoff ADC values and specificity and sensitivity in differential diagnosis.Results: ADC values of both benign lesions and malignant tumor under three sets of b value(respectively take 200,500,800s/mm~2)decreased gradually with the increasing b values.At the same b value,ADC values of benign lesions were significantly higher than that of malignant tumor.There was a certain overlap among the ADC values of different pathological types of lung carcinoma.ADC values of well-differentiated adenocarcinoma were higher than that of other histological types of lung carcinoma.ADC values of small cell lung carcinoma was lower than that of non-small cell lung carcinoma.When the b value was 200,500,800s/mm~2 respectively,the area under ROC curve(AUC)corresponding to ADC values of well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma respectively were 0.7458,0.7667,0.8250;that of lung benign lesions and malignant tumor were 0.8059,0.8432,0.8980 respectively;that of small cell lung carcinoma and non-small cell lung carcinoma were0.8177,0.8073,0.8750 respectively.All numbers above have diagnostic significance.When b value was taken at 800 s/mm~2,the AUC was the largest,and diagnostic efficacy was the highest;the cutoff ADC values of well-differentiated adenocarcinomas and low differentiated adenocarcinomas was 1.65×10-3mm~2/s,and the correspondingly sensitivity and specificity was 72.4% and 76.7% respectively;the cutoff ADC values of lung benign lesions and malignant tumor was 1.71×10-3mm~2/s,the correspondingly sensitivity and specificity was 95.8% and 80.0% respectively;the cutoff ADC values of small cell lung carcinoma and non-small cell lung carcinoma was 0.98×10-3mm~2/s,the correspondingly sensitivity and specificity was 83.3% and 84.4% respectively.Conclusion: In DWI images,the ADC values are of great value to distinguish between benign and malignant lesions of the lungs.Under the same b value,the ADC values of benign lesion is significantly higher than that of malignant lesions.The same b values(respectively take 200,500,800s/mm~2),ADC values are significant for diagnosing lung carcinoma of different pathological types;and when take a b value at 800 s/mm~2,diagnostic efficacy for well-differentiated adenocarcinomas and low differentiated adenocarcinomas is the highest. |
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