Objective:To quantitatively study the perfusion of pulmonary parenchyma in periphery of the lung cancer by spectral CT and to investigate the changes of the perfusion and to compare the difference of pulmonary parenchyma perfusion in distinct classifi-cation of the lung cancer. Methods:Eighty-one patients with lung cancer confirmed by pathology underwent chest unenhanced CT and enhanced CT scanning with spectral CT. The iodine contribution of pulmonary parenchyma from the lung cancer and corre-sponding mirror area in iodine-based material decomposition images of arterial phase were measured

then the average iodine concentration（ICa）was obtained. The difference of ICa between periphery of lung cancer and corresponding mirror area in all patients

central and peripheral type were analyzed and compared respectively. And the difference of ICa in periphery of lung cancer in different locations（central and peripheral type）

size（A group was d≤3 cm

B group was 3<d≤7 cm）

pathological types（squamous carcinoma

adenocarcinoma and small cell lung cancer）and degree of differentiation（low

low-middle and middle differentiation）were analyzed and compared. Results:（1）The ICa in periphery of the 81 lung cancer（1.26±0.42）mg/m L

the 32 central lung cancer（1.12±0.33）mg/m L and 49 peripheral lung cancer（1.35±0.45）mg/m L were all significantly lower than those in the corresponding mirror area（1.65±0.61）mg/m L

（1.63±0.69）mg/m L and（1.66±0.56）mg/m L（P <0.01）.（2） The ICa in periphery of the central lung cancer（1.12±0.33）mg/m L was significantly lower than that in periphery of the peripheral lung cancer（1.35 ±0.45） mg/m L（P<0.01）

and the ICa in periphery of the 10 cases of small cell lung cancer（0.94 ±0.20） mg/m L was lower than that in periphery of the 37 cases of squamous cell carcinoma（1.23 ±0.40）mg/m L and the 34 cases of adenocarcinoma（1.37±0.45）mg/m L（P<0.05）

but there was no significant difference between the latter two（P >0.05）.（3） The ICa in periphery of cancer had no significant difference（P>0.05）between different tumor sizes or between different degrees of differentiation. Conclusion:The perfusion of periphery of the lung cancer is generally reduced

furthermore

it is lower in periphery of the central lung cancer than that in periphery of the peripheral lung cancer

and it is lower in periphery of the small cell lung cancer than that in periphery of the non-small-cell lung cancer. The features of the spectral CT perfusion in periphery of the lung cancer have theoretical and clinical values.