Yo Won Choi

Low-dose and standard-dose unenhanced helical computed tomography for the assessment of acute renal colic: prospective comparative study.

Purpose: To compare the efficacy of low-dose and standard-dose computed tomography (CT) for the diagnosis of ureteral stones. Material and Methods: Unenhanced helical CT was performed with both a standard dose (260 mAs, pitch 1.5) and a low dose (50 mAs, pitch 1.5) in 121 patients suspected of having acute renal colic. The two studies were prospectively and independently interpreted for the presence and location of ureteral stones, abnormalities unrelated to stone disease, identification of secondary signs, i.e. hydronephrosis and perinephric stranding, and tissue rim sign. The standard-dose CT images were interpreted by one reviewer and the low-dose CT images independently by two reviewers unaware of the standard-dose CT findings. The findings of the standard and low-dose CT scans were compared with the exact McNemar test. Interobserver agreements were assessed with kappa analysis. The effective radiation doses resulting from two different protocols were calculated by means of commercially available software to which the Monte-Carlo phantom model was given. Results: The sensitivity, specificity, and accuracy of standard-dose CT for detecting ureteral stones were 99%, 93%, and 98%, respectively, whereas for the two reviewers the sensitivity of low-dose CT was 93% and 95%, specificity 86%, and accuracy 92% and 94%. We found no significant differences between standard-dose and low-dose CT in the sensitivity and specificity for diagnosing ureter stones (P>0.05 for both). However, the sensitivity of low-dose CT for detection of 19 stones less than or equal to 2 mm in diameter was 79% and 68%, respectively, for the two reviewers. Low-dose CT was comparable to standard-dose CT in visualizing hydronephrosis and the tissue rim sign. Perinephric stranding was far less clear on low-dose CT. Low-dose CT had the same diagnostic performance as standard-dose CT in diagnosing alternative diseases. Interobserver agreement between the two low-dose CT reviewers in the diagnosis of ureter stones and alternative diseases, the identification of secondary signs, and tissue rim sign were high, with kappa values ranging from 0.769 to 0.968. On standard-dose CT scans, the calculated mean effective radiation dose was 7.30 mSv for males and 10.00 mSv for females. On low-dose CT scans, the calculated mean effective radiation dose was 1.40 mSv for males and 1.97 mSv for females. Conclusion: Compared with standard scans using 260 mAs, low-dose unenhanced helical CT using a reduced tube current of 50 mAs results in a concomitant decrease in the radiation dose of 81%. Although low-dose CT was limited in its ability to depict small-sized calculi less than or equal to 2 mm, it is still comparable to standard-dose CT for the diagnosis of ureter stones and alternative disease.

Benign tumors of the tracheobronchial tree: CT-pathologic correlation.

OBJECTIVE The purpose of this essay is to illustrate the CT findings of variable benign tumors of the tracheobronchial tree and to correlate the CT and pathologic findings in 17 patients. CONCLUSION The tracheal tumors were eccentric, well-defined, polypoid masses in all cases. The endobronchial tumors were masses confined within the bronchus in all cases, and atelectasis or pneumonia of the distal parenchyma was frequently associated. Of the six hamartomas, one was a fatty mass, and two were nodules with calcification. The others were soft-tissue-density nodules. The lipomas manifested as fat density on CT scans in both cases. The other benign tumors were low-attenuating, soft-tissue-density masses without characteristic findings on CT scans.

Bronchiolitis obliterans syndrome in lung transplant recipients: correlation of computed tomography findings with bronchiolitis obliterans syndrome stage.

The purpose of this study was to correlate the extent of computed tomographic (CT) findings with the severity of respiratory dysfunction in lung transplant recipients with bronchiolitis obliterans syndrome (BOS). Eighty-nine conventional and 61 thin-section CT scans performed in 44 transplant recipients (17 bilateral, 27 single) with BOS were reviewed for mosaic attenuation, degree of bronchial dilation, bronchial thickening, central and peripheral bronchiectasis, mucus plugging, and air trapping. Findings on conventional and thin-section CT scans were correlated with BOS stage for bilateral and single-lung transplant recipients. In bilateral-lung recipients, a significant correlation existed, although weak, between BOS stage and findings of degree of bronchial dilation (P < 0.01), bronchial wall thickening (P = 0.01), peripheral bronchiectasis (P = 0.01), and mosaic attenuation (P = 0.01) on conventional CT; and bronchial wall thickening (P = 0.01) and mosaic attenuation (P = 0.03) on thin-section CT. In single-lung recipients, BOS stage correlated only with the finding of central bronchiectasis (P = 0.02) on conventional CT scans. No correlation was found between the extent of air trapping and BOS stage in either single- or bilateral-lung transplant recipients. CT findings are relatively poor indices of airflow obstruction in lung transplant recipients with BOS, particularly in those with single-lung transplants for emphysema.

Low-dose Spiral CT: Application to surface-rendered three-dimensional imaging of central airways

Purpose The purpose of this work was to assess the utility of low-dose spiral CT for three-dimensional imaging of the central airways. Method Spiral CT was performed in 15 patients using two tube currents (50 and 240 mA), producing 30 CT data sets. Surface-rendered virtual bronchoscopy (VB) and shaded surface display (SSD) images were assessed by three radiologists for image quality. The radiologists were also asked to compare 15 matched pairs each of 50 and 240 mA VB and SSD images, blindly select the 240 mA image, and record differences in diagnostic quality between the matched images. Results No significant difference in image quality was noted with 50 or 240 mA. Only 51.1% of 240 mA SSD and 51.1% of 240 mA VB images were correctly identified. Differences in diagnostic quality, noted in 84.4% of SSD and 33% of VB image pairs, were not ascribed to image noise. Conclusion Image quality of surface-rendered three-dimensional images of the central airways is preserved using a lower tube current.

Subaortic left innominate vein: radiologic findings and consideration of embryogenesis.

To propose a hypothesis about the embryogenesis of the subaortic left innominate vein, the authors reviewed the radiologic features of 14 patients diagnosed with subaortic left innominate vein made by computed tomography or magnetic resonance imaging scan. The authors retrospectively analyzed the level of the aortic arch, associated aortic arch anomalies, and the presence or absence of obliteration of the prevascular space. A high aortic arch was seen in 10 patients, five with a cervical, two with a right and, one with a double aortic arch. The prevascular space was occupied by the aortic arch, the great arteries, or both in all 10 patients with a high arch. In the remaining four patients with a normal aortic arch, the prevascular space was preserved, but abnormal elongation of the aortic segment between the left common carotid artery and the left subclavian artery was seen in three. The authors postulate that precardinal anastomosis can develop in any pathway where there is the available space. In the presence of abnormal elongation of the aortic arch and resultant widening of the subaortic space, the chance of the development of a subaortic left innominate vein increases.

Comparison between transauricular and transfemoral arterial access for hepatic artery angiography in a rabbit model.

PURPOSE To evaluate the feasibility of transauricular arterial access and compare the procedure time needed for hepatic artery angiography via transfemoral versus transauricular arterial access in a rabbit model. MATERIALS AND METHODS This study was approved by the research animal care and use committee. Twenty rabbits were divided into transfemoral (n = 10) and transauricular access groups (n = 10). The procedure consisted of shaving the hair, obtaining intraarterial access, performing hepatic artery angiography, and repairing the access site. A Mann-Whitney U test was used to compare the two groups in terms of the total procedure time and the time needed for each step. RESULTS Hepatic artery angiography was technically feasible in all animals in both groups. The time required for shaving was 55 seconds ± 9.9 in the transfemoral access group; shaving was unnecessary in the transauricular access group. The times needed to obtain intraarterial access, perform hepatic artery angiography, repair the access site, and perform the entire procedure in the transfemoral and transauricular access groups were as follows: 503.3 s ± 211.8 and 97 s ± 83.3 (P < .001), 229.6 s ± 90 and 310.7 s ± 211 (P = .705), 305.5 s ± 80.6 and 90 s ± 0 (P < .001), and 1,038 s ± 265.9 and 497.7 s ± 256.9 (P = 0.001), respectively. CONCLUSIONS Hepatic artery angiography is technically feasible via transauricular arterial access. The major advantages of transauricular arterial access versus transfemoral arterial access include a procedure time reduced by the omission of shaving and surgical cutdown.

Does contrast enhancement on CT suggest tumor response for chemotherapy in small cell carcinoma of the lung

Purpose The purpose of this article is to assess the correlation between contrast enhancement on CT and the tumor reduction ratio in small cell carcinoma of the lung after first-line chemotherapy. Materials and Methods Twenty-eight patients with small cell carcinoma of lung underwent preenhancement and postenhancement CT scans before and after first-line chemotherapy, followed by second-line chemotherapy in 7 patients who had relapsed. The authors retrospectively analyzed the correlation between the tumor reduction ratio and the CT numbers of contrast enhancement in each case by multiple regression analysis using SPSS. Results The mean tumor-reduction ratio was 58.2 ± 43.2% after first-line chemotherapy, and the mean CT enhancement was 33.2 ± 11.0 Hounsfield units (HU). The correlation coefficient between the tumor reduction ratio and the CT numbers of contrast enhancement was 0.57 (r2 = 0.32), and p value was < 0.002. After chemotherapy, more than 90% tumor reduction was seen in 11 patients. They revealed an average 41.9 ± 7.6 HU tumor enhancement. Less than 50% tumor reduction was seen in 10 patients. They revealed an average 26.2 ± 7.9 HU tumor enhancement. If these criteria of 30 HU contrast enhancement and 80% tumor reduction ratio were applied as a guide for chemotherapy response, the sensitivity, specificity, positive predictive value, and negative predictive value would be calculated as 85.7%, 84.6%, 85.7%, and 84.6%, respectively. Conclusion In small cell carcinoma of the lung, it is statistically proven that the more enhanced tumor on CT, the better response to chemotherapy. Tumor enhancement of 30 HU is a suggestive guide for chemotherapy response in patients with small cell carcinoma.

Mucormycosis of the central airways: CT findings in three patients.

Computed tomographic (CT) findings are described in three diabetic patients with central airways mucormycosis. The CT findings of the tracheobronchial mucormycosis include enhancing areas of mural thickening (n = 3), luminal narrowing (n = 3), intramural air (n = 3), low-attenuation nonenhancing bronchial wall thickening (n = 2), and bronchonodal fistula formation (n = 1). These CT features in a diabetic patient should raise a high index of suspicion for tracheobronchial mucormycosis, particularly when typical radiographic features of pulmonary tuberculosis are absent.

Characteristics of Coronary Artery to Pulmonary Artery Fistula on Coronary Computed Tomography Angiography

Objective The aim of the study was to evaluate the characteristics of coronary artery-to-pulmonary artery fistula (CPAF) found by coronary computed tomography (CT) angiography. Methods Among 10,121 cases of coronary CT angiography performed for 7 years, we found 32 cases of CPAF. We retrospectively evaluated the demographics, clinical symptoms, and anatomical characteristics such as the origin, number of origins, course, opening site of the fistula, and the presence of aneurysmal changes (defined as dilatation 1.5 times the diameter of the origin). We also categorized the fistula openings according to size compared with that of the proximal left anterior descending coronary artery. Results The patients were 14 men and 18 women with a mean (range) age of 56.5 (34–86) years. Nineteen patients had no related symptoms, and the other 13 patients had symptoms such as angina, chest discomfort, palpitations, or shoulder pain. Among these patients, 2 patients were diagnosed with coronary artery disease. The origins of CPAF were single (n = 15, 46.9%) or multiple (n = 17, 53.1%). The CPAFs arose most commonly from the conus branch of the right coronary artery (n = 20, 62.5%) and proximal left anterior descending (n = 17, 53.1%). All CPAFs coursed anteriorly to the main pulmonary artery and drained into the anterolateral aspect. Twenty-five patients (78.1%) exhibited aneurysmal changes. The openings were small in 13 (40.6%), medium in 13 (40.6%), and large in 6 (18.8%) patients. Conclusions More than half of patients with CPAF had no related symptoms. Coronary artery-to-pulmonary artery fistula may have a single origin or multiple origins. All of the CPAFs coursed anteriorly to the main pulmonary artery and drained into the anterolateral aspect; the CPAFs identified here frequently exhibited aneurysmal changes.

Telangiectatic pulmonary arteriovenous malformation.

Telangiectatic pulmonary arteriovenous malformation is defined as a pulmonary arteriovenous malformation involving every segmental artery of at least one lobe of the lung. The authors report a case of telangiectatic pulmonary arteriovenous malformation in the left lower lobe of the lung.