Low-dose celiac CT angiography with fixed current-time product / 中华放射学杂志

Objective To characterize the feasibility of low-dose CT angingraphy on 16-slice multislice computed tomography (16-MSCT), and its relationship to the noise in the pre-contrast image and enhancement value.Methods Forty-three consecutive patients (male 21, female 22, mean age 59 years, median age 56 years) underwent abdominal 16-MSCT (Toshiba Aquilion 16) with constant scanning parameters including 120 kVp, a 0.5-second gantry rotation time, a pitch of 0.938: 1, and 16×1-mm detector collimation.The mA was set at 200 in the pre-contrast scan and 160 in the contrast-enhanced scan.The arterial phase images were retrospectively reconstructed with 1-mm slice thickness, 0.8 mm interval.The pre-contrast noise was defined as the standard deviation (SD) of the aorta at the level of right posterior crura of diaphragm.The enhancement of aorta was also measured at level of celiac artery.The volume rendering of CT angiography was made and classified into three grades (excellent, good, bad).Receiver operating characteristic curve (ROC) was used to evaluate the relationship between the image quality of CT angiography and noise in the pre-contrast image and enhancement value.Results Twenty-five cases had the aorta enhancement between 300.0--400.0 HU.The sensitivity and specificity of excellent CTA image was 75% and 62%, respectively when the SD was 12.00.Eighteen cases had the aorta enhancement more than 400.0 HU.The sensitivity and specificity of excellent CTA image was all 100% when the SD was 12.25, and 100% and 75%, respectively when the SD was 13.35.The area under curve of CTA image quality and enhancement in receiver-operated characteristic analysis was O.907.The enhancement was more than 356.7 HU when the sensitivity and specificity of excellent CTA image was 100% and 60%, respectively, and 389.8 HU when 78% and 80%.When the enhancement was more than 442.4 HU, the specificity of excellent CTA image was 100%.Conclusions MSCT angiography with low radiation dose is feasible.Good CT angiography demands great enhancement, and then, the needed mAs is lower when the SD is smaller.

CT in Combination with MRI in Diagnosis and Differential Diagnosis of Chondrosarcoma / 实用放射学杂志

Objective To investigate CT in combination with MRI in diagnosing and differential diagnosing chondrosarcoma.Methods CT and MRI findings pathologically in 19 cases of chondrosarcoma proved were analyzed retrospectively.Results On CT,the tumors appeared as bony destruction in 15 cases,soft tissue masses in 14 cases,and with multiple calcifications in different shape.Postcontrast CT scan demonstrated peripheral and septal enhancement in 2 cases,and inhomogeneous enhancement in 3 cases.On MRI,the chondrosarcomas were hypointense or isointense on T1WI,heterogeneous hyperintense on T2WI.Postcontrast MRI demonstrated peripheral and septal enhancement with wreath-or honeycomb-like appearance in 9 cases,heterogeneous enhancement in 2 cases,obvious enhancement in 2 cases.On fat-suppression T2WI,the boundary and size of lesions were demonstrated clearly.The phylloid and cauliflower-like shape of tumors were displayed better on sagital and coronal position.Conclusion CT and MRI are both important in diagnosis and differetial diagnosis of chondrosarcoma,the combination of the two methods may improve the diagnosing accuracy of this tumor and minimize misdiagnosis.

Application of Multi-slice Spiral CT Three Dimensional Reconstruction in Diagnosis of Mechanical Intestinal Obstruction / 实用放射学杂志

Objective To investigate the diagnostic Value of multi-slice spiral CT 3-Dimensional reconstruction in intestinal obstruction.Methods 28 Patients with malignant lesions of colon underwent volume scanning using multislice helical CT.Four types of reconstruction included multiple planner reconstruction(MPR),CT virtual colonoscopy(CTVC),shaded surface display(SSD)and raysum.The results were compared with those of colonoscopy and patholog.Results CT diagnostic accurate rate was 100%,and the accurate rate of the cause was 96% in intestinal obstruction,including primary or secondary neoplasms(18/28),abhesions(2/28),bowel torsion(2/28)and external or internal hernias(3/28) and gallstone ileus(3/28).Conclusion There were advantages and disadvantages in diagnosis of mechanical intestinal obstruction with MPR,CTVC,SSD and Raysum respectively.The combined use of the four post-processing technigues can be more helpful to precise localizing and qualitative diagnosis of lesions.MPR should be the optimal post-processing technigues for the diagnosis of intestinal obstruction

CT Diagnostic Value of Gastrointestinal Stromal Tumors / 实用放射学杂志

Objective To analyze CT features of gastrointestinal stromal tumors(GIST) and to evaluate its value in diagnosis of thedisease.Methods Both plain and enhanced CT findings in 32 cases with GIST pathologically-proved were retrospectively analyzed.Gastrointestinal air-barium double contrast radiography was performed in 15 patients . Results The tumors originated from the stomach (n=18),jejunum(n=4),ileum(n=3),esophagus(n=2),mesentery(n=2),ascending colon(n=1),rectum(n=1) and greater omentum(n=1).Of 32 GIST,12 were benign and 20 were malignant.In benign GIST ,the diameter of the tumor was less than 5cm,with clear margin and homogeneous density.In malignant GIST,the diameter of the tumor was more than 7 cm,the tumors were lobular in shape ,with necrosis within the tumor ,the tumor had large and deep ulcers,invasion of adjacent tissues and metastasis.The positive predictive value of CT for location of GTST was 96.9%(31/32),the positive predictive value of CT for differentiation of benign and malignant GIST was 93.8%(30/32).Conclusion CT is of great value in diagnosis of GIST.It can be considered as a supplement to X-ray barium meal examination and can provide useful informations for early diagnosis and for the evaluation of the treatment and prognosis.

CT Value in Examining Intestinal Tumor Obstruction / 实用放射学杂志

Objective To analyze the CT features of intestinal tumor obstruction, and explore its CT value.Methods CT manifestation and clinical materials of intestinal tumor obstruction proved by surgical findings or endoscopy biopsy in 35 cases were analyzed restrospectively, and compared with the results of surgery-pathology and endoscopy. Results CT findings were consistence with the results of surgery-pathology and endoscopy in 33 of 35 cases. The CT diagnostic accuracy of intestinal obstruction was 100%. And the accuracy of the cause was 94%, including colon carcinoma in 25, lyphoma in 5, gastrointestinal stromal tumor in 2, and lipoma in 3.Conclusion CT has unique advantage in examining intestinal tumor obstruction, not only for definiting the existence of the obstruction, but also locating the site of obstruction diagnosing the cause and chosing the appropriate treatment.