| PurposeTo assess the value of detecting the pathognomonic signs of peripheral lung cancer byusing multi-direction adjusting multi-planar reformation (MPR) after multi-slice spiralCT isotropic scanning.MethodsForty five cases with pathologically proved peripheral lung cancer were scanned bymulti-slice spiral CT using isotropic scanning parameters (Slice thickness 5.0mm,slicespacing 5.0mm, 0.6 mm collimation) Then, raw data was reconstructed using threedimensional canonical algorithm with 1.0mm slice thickness and 75% reconstructioninterval. MPR was performed in the workstation. (1) We obtained the multiple planarreconstruction (MPR) images along the orientation of vessels and bronchus, andobserved the manifestation of vessel convergence and CT bronchus sign of the tumor.MPR images were compared with thin-slice axial images. (2) The center of lungcancer was regarded as a fixed point aroud which images were rotated separatelysurround the X, Y and Z axis to seek for the best image. Interior and margin sign ofthe tumour observed in MPR were compared with thin-slice axial images. Tworadiologists analysis the images independently with double-blind method inworkstation.Results1 The relationship between tumor and the structures around the tumor : (1) The relationship between the tumor and the bronchus: 39 cases can be demonstrated by MPR. The displaying rate of MPR of MPR was higher than that of thin-slice axial images (P <0.05). The relations of the peripheral lung cancer and bronchus were divided into 4 types. Type I and I were most common in this study.(2) The relationship between tumor and nearby blood vessels: According to the degree and numbers of vessels, the vascular convergence sign was divided into 3 grades. Most of the cases belonged to grade I and grade II in our study. According to the type of blood vessel, the vascular convergence sign was divided into 3 types: type I (pulmonary artery is superiority); type II, (pulmonary arteries and veins were difficult to differentiate the superior vessels); type III (pulmonary vein is superiority).(3) The relationship between the tumor and the pleural membrane: The pleural membrane around chest wall demonstrated by MPR was similar to the axial image. But MPR provided higher demonstration of the interlobar pleura than axial thin-slice images.2 Detection of basic signs of peripheral lung cancer on MPR(1) Comparing with thin-slice axial images, MPR provided higher detecting rate in showing CT bronchus sign, deep lobulation, vascular convergence sign and break of interlobar pleura(P<0.05).The incidence of the speculation and pleural indentation detected on the MPR images was similar to that on the axial thin-section images.(2) Multi-direction adjusting MPR had an advantage over axial thin-section images in judging the presence of the vacuolar sign and CT bronchus sign.(3) Multi-slice spiral CT with MPR was superior to axial thin-slice images in detecting the presence and the numbers of the signs of peripheral lung cancer (P<0.05).Conclusion1 MSCT MPR achieved the practical significance of the isotropic scanning, We could obtain many random positions and the same level resolution images only need axis position scanning one time without increasing radiation and t expense.2 MPR was more suit to observing and understanding the relationship of tumor and bronchus. Using axial images and MPR together were expected to guide bronchofibroscope to draw the materials effectively.3 Multi-direction adjusting MPR could demonstrate the location of the tumor and adjacent relations around the tumor accurately. It provided the higher detecting rate and the distinguishing ability of the tumor interior and the peripheral characteristic sign.ApplicationMulti-slice spiral CT with MPR provides more information for diagnosis and differential diagnosis about peripheral lung cancer, and plays an important role in guiding bronchofibroscope to biopsy and in evaluating tumor before the surgery. With universal application of multi-slice spiral CT, MPR will become the standard diagnostic procedure of the peripheral lung cancer.
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