Clinical Study On Diagnosis Of Pulmonary Space-occupying Diseases With Dual-energy Subtraction Technique

【Background and Object】Pulmonary diseases especially for space-occupying lesions are one main andcommon danger of human health. The clinical signs. and symptoms of pulmonaryspace-occupying lesions are often vague or nonspecific, therefore early diagnosis andtherapy is the key point to elevate cure rate and decrease death rate. The medicalimageology including radiography, CT and MRI is the important examination aboutpulmonary space-occupying lesions. Although the application of CT and MRI ispopular now, conventional radiography, characterized with convenience; easyperformance; cheapness and low dose, is the main examination in diagnosing chestdiseases and plays the important role in diseases' prevention diagnosis andtherapeutic effect observation,.In the conventional chest radiography, the respiratory tract and pulmonary fieldsoverlapped with mediastinum; disphragmatic muscles; ribs and collarbones can't beviewed clearly, which confine the detection of lesions and observation on theirimaging features, meanwhile make diagnosis more difficult even bring misseddiagnosis and misdiagnosis. The invention of digital radiography brings huge changesfor X-ray diagnosis on account of its low dose; fast collection and abundant imaging information, which show pulmonary fine structures more clearly than conventionalchest radiography. However, the overlapped images of pulmonary and bony thoraxstill exist, so the observation, analysis and diagnosis on part pulmonary diseases areconfined yet.Dual Energy Subtraction (DES) retrieves the shortcoming of conventional X-rayand DR chest radiography. Dual Energy Subtraction based on DR, according to thedifference of X-ray's attenuation way in bone and soft tissue, generates thecharacteristic views: a soft-tissue image with the bones "subtracted" and an simpleimage of the bones, which improve the image resolution largely and elevate thedetection rate and diagnosis exact rate on pulmonary space-occupying lesionsobviously combination with original image.The capability of displaying on normal pulmonary markings and diagnosis onpulmonary space-occupying lesions with conventional digital radiography (CDR) andDES soft-tissue image are compared in this study. The following contents arediscussed: (1) the value of displaying on normal pulmonary markings with CDR andDES chest radiography provides some rationale for study pulmonary diseases withDES technique; (2) the value of diagnosis and differential diagnosis on pulmonaryspace-occupying lesions with CDR and DES chest radiography provides moreimaging information than CDR and provides practical guidance for clinical studywith DES technology.【Materials and methods】1. Clinical information(1) From January 2005 to January 2007, 30 health patients (14 men and16women; mean age: 38 years; range: 24～55 years) of all patients performed DESwere involved according to some related standards (detail in P₃). (2) From January2005 to January 2007, of all patients performed DES, 78 patients (51 men and 27women; mean age: 54 years; range: 21～83 years) with pulmonary space-occupyingdiseases were involved according to some related standards (detail in P₁₃). The caseswere 24 benign lesions (mean age: 48 years; range: 21～78 years) which includedpulmonary tuberculosis (13 cases), organized pneumonia (4 cases), fibrosclerosisnodules (2 cases), nosomycosis (2 cases), inflammatorypseudotumor (1 case),hamartoma (1 case) and pulmonary abscess (1 case); and 54 malignant lesions (meanage: 57 years; range: 22～83 years) which included pulmonary cancer (51 cases) andmetastatic tumor (3cases). (3) From January 2005 to January 2007, of all patientsperformed DES, 4 patients related with differential diagnosis were involved: thyroidlesion (1 case), tracheocarcinoma (1 case), mediastinal and hilar lymph nodescalcification (1 case), osseous metastasis (1 case).2. Equipment and methodsChest radiographs were acquired using direct digital radiography chest system(Revolution XR/d, GE Medical System). All patients' standard PA radiographs wereperformed with CDR and DES at the same time. All examination were permitted bypatients. Breathholding after deep inspiration, the images were acquired in adual-exposure technique with 200 msec between high-(120-KV, 320-mA) and low-(60-KV, 200mA) energy exposure. The exposure conditions were controlledautomatically on the basis of patients' body type. Before the examination, patientswere guided to control respiration in order to cooperate with doctors. The three DESimages consisted of CDR chest radiograph as well as DES soft-tissue image and thebone image.3. Pulmonary zones about observation pulmonary markingsAccording to literatures and principle of pulmonary markings' distribution,pulmonary fields were divided into 12 zones: right upper lateral/left upper lateral—R1/L1, right upper medial/left upper medial—R2/L2, right middle lateral/left middle lateral—R3/L3, right middle medial/left middle medial—R4/L4, right lower lateral/leftlower lateral—R5/L5, right lower medial/left lower medial—R6/L6.4. Image evaluationDisplayer: double screens liquid crystal display, EIZO G11 type.PACS: START-PACS invented independently by Southern Medical University.The CDR and DES images were downloaded from PACS to hard disk ofcomputers. Four experienced radiologists participated in this study. Not given anyclinical information and results, the radiologists presented images alone inside theworkroom with suitable moisture, temperature and light. No limit was imposed onread time and postprocessing function of PACS. The following contents wereobserved: (1) the capability displaying pulmonary markings in different fields of 30normal CDR and DES chest radiographs. (2) qualitation (benign or malignant)diagnosis and imaging features of every lesion in 78 cases with pulmonary space--occupying CDR and DES chest radiographs.To be familiar with pulmonary zones, criterions, observation contents andoperative procedure, preliminary experiments were performed before formalexperiments.5. Statistics analysis(1) The most opinion among 4 experienced radiologists was considered as thefinal statistical datum. If every radiologist's result isn't coincident or coincident rateamong 4 radiologists is same, the final results were acquired by discussion of everyradiologist.(2) In different pulmonary zones of 30 health objects, the number of displayingpulmonary markings well or badly was analyzed in DES and CDR chest radiographs.It was analyzed if there was difference between DES and CDR chest radiographs andwhich was better between them. (3) Compared with gold standard, the exact rate of qualitation diagnosis onbenign and malignant lesions was analyzed. In total 78 cases, 54 malignant cases and24 benign cases, it was analyzed separately that if there was difference in diagnosiscapability between DES and CDR chest radiographs and which was better betweenthem.(4) Compared with benign space-occupying lesions, the specificity andsensitivity of diagnosis on malignant space-occupying lesions with CDR and DESwere analyzed.McNemar analysis was performed with spss10.0 software. Probability values＜0.05 were considered statistically significant.【Results】1. After statistical analysis about 30 health objects, there was statisticalsignificance (P＜0.05) in the difference about displaying on pulmonary markingsbetween CDR and DES chest radiographs, it was better in DES than CDR. This 8pulmonary zones were as follows:In right upper medial (R2) zone, better manifestation rate were 73.3% in DESand 26.7% in CDR; P=0.007. In right middle lateral (R3) zone, better manifestationrate were 76.6% in DES and 26.7% in CDR; P=0.006. In right middle medial (R4)zone, better manifestation rate were 80.0% in DES and 26.7% in CDR; P=0.002. Inright lower lateral (R5) zone, better manifestation rate were 70.0% in DES and 30.0%in CDR; P=0.029.In left upper medial (L2) zone, better manifestation rate were 73.3% in DES and30.0% in CDR; P=0.015. In left middle lateral (L3) zone, better manifestation ratewere 73.3% in DES and 30.0% in CDR; P=0.019. In left middle medial (L4) zone,better manifestation rate were 80.0% in DES and 23.3% in CDR; P=0.002. In leftlower lateral (L5) zone, better manifestation rate were 76.7% in DES and 23.3% in CDR; P=0.004.2. In 30 health objects, there wasn't statistical significance (P＞0.05) in thedifference about displaying on pulmonary markings between CDR and DES chestradiographs. This 4 pulmonary zones were as follows:In right upper lateral (R1) zone, better manifestation rate were 53.3% in DESand 46.7% in CDR; P=0.845. In left upper lateral (L1) zone, better manifestation ratewere 63.3% in DES and 43.3% in CDR; P=0.327. In right lower medial (R6) zone,better manifestation rate were 63.3% in DES and 40.0% in CDR; P=0.230. In leftlower medial (L6) zone, better manifestation rate were 36.7% in DES and 60.0% inCDR; P=0.230.3. Of 78 patients with pulmonary space-occupying lesions, the results aboutstatistical analysis showed: (1) There was statistical significance (P=0.007) in thedifference about exact rate of diagnosis on total 78 cases; it was better in DES chestradiographs (76.9%) than CDR (62.8%). (2) There was statistical significance(P=0.012) in the difference about exact rate of diagnosis on 54 malignant cases; itwas better in DES chest radiographs (81.5%) than CDR (64.8%). (3) There wasn'tstatistical significance (P=0.625) in the difference about exact rate of diagnosis on 24benign cases; although it was better in DES chest radiographs (66.7%) than CDR(58.3%).4. Of 54 patients with pulmonary malignant space-occupying lesions, thesensitivity were 64.8% (CDR) and 81.5% (DES), the specificity were 58.3% (CDR)and 66.7% (DES).【Conclusion】1. Bronchus' trend is certain coincident with shape and distribution ofpulmonary markings which can reflect some information about bronchus. In DESsoft-tissue chest radiographs with small artifact and few overlapping zones, pulmonary markings are viewed better than CDR chest radiographs, which providereliable rationale for pulmonary diseases with DES technique and has large referencevalue in imaging diagnosis on pulmonary space-occupying lesions such asinflammatoryp seudotumor, metastatic tumor and bronchiogenic cancer et al.2. For imaging diagnosis and differential diagnosis on pulmonary space-occupying lesions (especially for malignant tumor), DES image provide moreabundant information than CDR chest radiographs. Compared with CDR chestradiographs, DES image have certain dominance which benefits to elevate accuraterate, specificity and sensitivity of diagnosis on pulmonary space-occupying lesionsand cut down misdiagnosis rate of it with simple CDR.