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【Objective】To comparatively evaluate the single role and to discuss the feasibility of combining application in the diagnosis of solitary pulmonary nodules(SPN) with 18F-FDG Dual Head Tomography Coincidence(DHTC) and CT scan by the study of 220 cases.【Methods】From 2009 Aug to 2010 Oct,220 undiagnosed SPN in Shanghai Pulmonary Disease Hospital were examined with DHTC and CT scan.We used visual analysis ,and marked abnormal radioiodine points in the images of DHTC,according to the degree,the SPNs were divided into 5 levels,and defined level 0~1 as benign(negative), level 2~4 as malignant(positive); according to the features in CT, the SPNs were divided into 5 levels, level 1~3 as benign(negative), level 4~5 as malignant(positive).When the DHTC’s diagnosis disagreed with CT’s, we applied these principles:if d<1.5cm ,we chose CT’s result,if d≥1.5cm,we added the levels of CT and DHTC, if the summation was greater than (equal to) 4,and the DHTC’s level was also greater than (equal to) 3,the SPN was thought to be malignant, if the summation was less than 4,and the DHTC’s level was also less than 3,the SPN was thought to be benign.The diagnosis of CT,DHTC and CT combined with DHTC were compared with postoperative pathological outcome.The diagnostic values of CT,DHTC and CT combined with DHTC were assessed by calculating sensitivity,specificity,accuracy,positive and negative predictive value.All data were analyzed with SPSS17.0 for significance by using theχ2-test.Values of P<0.05 were accepted as significance.【Results】 There were 190 malignant and 30 benign nodules in the 220 SPNs.In all 190 malignant nodules,there were 144 adenocarcinnma(including pure 103 Ads,8 BAC,33 Ads combined with BAC),26 squamous carcinomas,20 adenosquamors carcinomas.In 30 benign nodules,10 organized pneumonia,8 tuberculomas,4 cryptococcus,4 sclerosing hemangioma,3 hamartoma,1 bronchocele.In CT results,138 of 190 malignant nodules were diagnosed as positive and 52 as negative,18 of 30 benign nodules were diagnosed as positive and 12 as negative;in DHTC results,118 of 190 malignant nodules were diagnosed as positive and 72 as negative,7 of 30 benign nodules were diagnosed as positive and 23 as negative;in CT combined with DHTC results,160 of 190 malignant nodules were diagnosed as positive and 30 as negative,10 of 30 benign nodules were diagnosed as positive and 20 as negative. The sensitivity, specificity,accuracy,positive and negative predictive value of CT,DHTC and CT combined with DHTC prediction were:73%,40%,68%,88%,19%;62%,77%,64%,94%,24%;84%,67%,82%,94%,40%.To evaluate SPN,compared with CT,the combined group had significant difference in all indexes besides positive predictive value(χ2=7.527,10.909,6.278,4.286,P<0.05);but with DHTC, the combined group didn’t have significance in specificity and positive predictive value(χ2=0.739,4.763;P>0.05); DHTC had similar sensitivity and superior specificity to CT (χ2=4.788,8.297;P<0.05). We divided 220 SPNs into 4 groups by its size: 0~1.0cm(M:B11/6),1.0~1.5cm(36/8),1.5~2.0cm(70/5),2.0~3.0cm(73/11).The indexes of CT prediction in the four groups were: 18%, 50%, 29%, 40%, 25%; 67%, 38%, 61%, 83%, 20%; 71%, 0,67%, 91%, 0;85%, 55%, 81%, 93%, 35%. The indexes of DHTC prediction were: 9%, 100%, 41%, 100%, 38%; 33%, 75%, 41%, 86%, 20%; 66%, 60%, 65%, 96%, 11%;81%,73%,80%,95%,36%. The indexes of combined group prediction were: 27%, 83%, 47%, 75%, 38%; 75%, 63%, 73%, 90%, 36%; 84%, 80%, 84%, 98%, 27%; 95%, 55%, 90%, 93%, 60%. Sensitivity, accuracy and negative predictive value of CT combined with DHTC predicting SPNs with different size were higher than CT and DHTC solely.However,only compared with DHTC,the 1.0~1.5cm,1.5~2.0cm and 2.0~3.0 cm groups had significant difference in sensitivity(χ2=12.587,6.438,6.337;P<0.05),the 1.0~1.5 cm and 1.5~2.0 cm groups had significant difference in accuracy (χ2=9.078, 6.908; P<0.05 ); there were no difference among CT, DHTC and the combined group in specificity, positive predictive value (χ2=3.827, 2.305, 6.700, 1.071; 1.079, 0.659, 3.469, 0.394; P>0.05 ); the sensitivity of CT predicting SPNs with different size was better than DHTC, but only the 1.0~1.5 cm group have significant difference in sensitivity (χ2=8.000, P<0.05 ).【Conclusion】The values of 18F-FDG DHTC and CT scan were obvious in the evaluation of SPN,but the characters of SPN had overlaps in the qualitatively and size different nodules. Because of DHTC’s resolution limit ,most of the SPNs between 0 to 1.5 cm had negative 18F-FDG uptake,the sensitivity was lower than CT,so we can choose CT to get the qualitative analysis of these SPNs. The sensitivity of CT combined with DHTC predicting SPNs between 1.5 to 3.0 cm was higher than CT and DHTC solely,so we can choose combined diagnosis.The CT result was positive,while DHTC negative,we can reexamine it with CT scan in 3 months;do this,we can reduce CT’s false positive and DHTC’s false negative to improve the accuracy of diagnosis. CT combined with DHTC is an effective and accurate method to locate and qualitative SPN,which not only combine the anatomy with functional information, but also the high sensitivity of CT with high specificity of DHTC.As for its high accuracy,many patients can avoid unnecessary biopsies and surgeries,so it not only reduce the trauma,but save much cost, CT combined with DHTC have good value to diagnose SPNs in clinical applications.
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