Koun Sik Song

Useful Ct Findings for Predicting the Progression of Aortic Intramural Hematoma to Overt Aortic Dissection

Purpose The purpose of this work was to assess useful CT findings for predicting the progression of aortic intramural hematoma to aortic dissection. Method We analyzed the CT findings of 29 patients with aortic intramural hematoma with regard to the following: involved site, maximum thickness of hematoma, presence or absence of compression of true lumen, and pericardial and pleural effusion. CT findings were compared with those of the patients who progressed to aortic dissection (Group I) and those who did not (Group II). Each CT finding was evaluated with independent t test and Mann-Whitney U test (p < 0.05). Results Seven of 8 cases of Type A aortic intramural hematoma and 3 of 21 cases of Type B aortic intramural hematoma progressed to aortic dissection. The type of aortic intramural hematoma, maximum thickness of hematoma, compression of true lumen, and pericardial or pleural effusion were significantly different in Groups I and II. Conclusion Type A aortic intramural hematoma, maximum thickness of hematoma, compression of true lumen, and pericardial or pleural effusion are the useful CT findings for predicting the progression of aortic intramural hematoma to aortic dissection.

Acute and chronic complications of aortic intramural hematoma on follow-up computed tomography: incidence and predictor analysis.

Objective: To ascertain the incidence of acute and chronic complications of aortic intramural hematoma (IMH) and to analyze the predictors of the development of each complication. Materials and Methods: This retrospective study includes 107 consecutive patients diagnosed with aortic IMH by means of computed tomography (CT) during the period from January 1998 to December 2003 and followed up with serial CT examinations (median follow-up period, 320 days). There were 36 patients with type A and 71 with type B IMH. Initial and follow-up CT scans were reviewed, with special attention given to the development of complications, such as increase in the thickness of IMH, clinical and hemodynamic evolution requiring urgent surgery, and development of aortic dissection and/or aneurysm. If each complication developed within 30 days after the initial episode, we classified it as an acute complication; the others were classified as chronic complications. The time interval between the initial and the subsequent CT examination showing each complication was recorded. To identify the predictors of each complication, we analyzed the demographic and CT findings with regard to the following factors: age, sex, maximum thickness of the hematoma, maximum aortic diameter on initial CT examination, ulcerlike projection (ULP) on initial and follow-up CT examinations, and the degree of atherosclerosis. The Cox proportional hazards regression model with stepwise multivariate analyses was used to determine the significant predictors of each complication. Results: Sixteen patients had acute complications consisting of aortic dissection (n = 7), aortic aneurysm (n = 6), and acute clinical and hemodynamic evolution requiring operation (n = 3). Three additional patients with aortic dissection (n = 1) and aneurysm (n = 2) underwent emergency surgery. Twenty-three patients with chronic complications had aortic dissection (n = 3), and aortic aneurysm (n = 20). Cox proportional hazards regression model revealed that the maximal diameter of involved aorta is the only significant predictor of the development of acute complications (P = 0.006), whereas the age (P = 0.040), type A IMH (P = 0.015), presence of ULP (P = 0.015), and newly developed ULP as revealed on follow-up CT examination (P = 0.032) were significant predictors of the development of chronic complications. With regard to the aortic dissection in 10 patients (9.3%; type A/B ratio, 5:5; median time interval, 34 days), Cox proportional hazards regression model revealed that the maximal thickness of the hematoma is the only significant predictor (P = 0.018). Twenty-one saccular and 5 fusiform aneurysms (24.3%) developed, as revealed on follow-up CT examinations (median time interval, 180 days). The presence of ULP (P = 0.030), type A (P = 0.038) and the maximal thickness of the hematoma (P = 0.017) were significant predictors for the development of an aneurysm. Conclusions: The maximum thickness of a hematoma on the initial CT is the significant factor predicting the development of aortic dissection and aortic aneurysm. Patients with type A IMH and ULP, as revealed by initial and short-term follow-up CT examinations, should be carefully followed up with subsequent CT examination to monitor the development of an aortic aneurysm, which is a relatively common chronic complication of IMH.

Semi-automatic measurement of the airway dimension by computed tomography using the full-with-half-maximum method: a study of the measurement accuracy according to the orientation of an artificial airway.

Objective To develop an algorithm to measure the dimensions of an airway oriented obliquely on a volumetric CT, as well as assess the effect of the imaging parameters on the correct measurement of the airway dimension. Materials and Methods An airway phantom with 11 poly-acryl tubes of various lumen diameters and wall thicknesses was scanned using a 16-MDCT (multidetector CT) at various tilt angles (0, 30, 45, and 60°). The CT images were reconstructed at various reconstruction kernels and thicknesses. The axis of each airway was determined using the 3D thinning algorithm, with images perpendicular to the axis being reconstructed. The luminal radius and wall thickness was measured by the full-width-half-maximum method. The influence of the CT parameters (the size of the airways, obliquity on the radius and wall thickness) was assessed by comparing the actual dimension of each tube with the estimated values. Results The 3D thinning algorithm correctly determined the axis of the oblique airway in all tubes (mean error: 0.91 ± 0.82°). A sharper reconstruction kernel, thicker image thickness and larger tilt angle of the airway axis resulted in a significant decrease of the measured wall thickness and an increase of the measured luminal radius. Use of a standard kernel and a 0.75-mm slice thickness resulted in the most accurate measurement of airway dimension, which was independent of obliquity. Conclusion The airway obliquity and imaging parameters have a strong influence on the accuracy of the airway wall measurement. For the accurate measurement of airway thickness, the CT images should be reconstructed with a standard kernel and a 0.75 mm slice thickness.

Detection of Clustered Microcalcifications on Mammograms Using Surrounding Region Dependence Method and Artificial Neural Network

Clustered microcalcifications on X-ray mammograms are an important sign in the detection of breast cancer. A statistical texture analysis method, called the surrounding region dependence method (SRDM), is proposed for the detection of clustered microcalcifications on digitized mammograms. The SRDM is based on the second-order histogram in two surrounding regions. This method defines four textural features to classify region of interests (ROIs) into positive ROIs containing clustered microcalcifications and negative ROIs of normal tissues. The database is composed of 64 positive and 76 negative ROI images, which are selected from digitized mammograms with a pixel size of 100 × 100 μm2 and 12 bits per pixel. An ROI is selected as an area of 128 × 128 pixels on the digitized mammograms. In order to classify ROIs into the two types, a three-layer backpropagation neural network is employed as a classifier. A segmentation of individual microcalcifications is also proposed to show their morphologies. The classification performance of the proposed method is evaluated by using the round-robin method and a free-response receiver operating-characteristics (FROC) analysis. A receiver operating-characteristics (ROC) analysis is employed to present the results of the round-robin testing for the case of several hidden neurons. The area under the ROC curve, Az, is 0.997, which is achieved in the case of 4 hidden neurons. The FROC analysis is performed on 20 cropped images. A cropped image is selected as an area of 512 × 512 pixels on the digitized mammograms. In terms of the FROC, a sensitivity of more than 90% is obtained with a low false-positive (FP) detection rate of 0.67 per cropped image.

Intravascular papillary endothelial hyperplasia of the lung.

Intravascular papillary endothelial hyperplasia (IPEH) is a benign vascular endothelial proliferation, which is usually confined to the lumen of preexisting vessels or vascular malformation. IPEH usually presents as a single lesion, and it rarely involves the lung. We describe a rare case of intrapulmonary IPEH presented by multiple variably sized, well-defined nodules occurring in a 52-year-old woman.

Automatic measurement of oblique-oriented airway dimension at volumetric CT: effect of imaging parameters and obliquity of airway with FWHM method using a physical phantom

This study is conducted to assess the influence of various CT imaging parameters and airway obliquity, such as reconstruction kernel, field of view, slice thickness, and obliquity of airway on automatic measurement of airway wall thickness with FWHM method and physical phantom. The phantom, consists of 11 poly-acryl tubes with various inner lumen diameters and thickness, was used in this study. The measured density of the wall was 150HU. The airspace outside of tube was filled with poly-urethane foam, whose density was -900HU, which is similar density of emphysema region. CT images, obtained with MDCT (Sensation 16, Siemens), was reconstructed with various reconstruction kernel (B10f, B30f, B50f, B70f and B80f), different field of views (180mm, 270mm, 360mm), and different thicknesses (0.75, 1, and 2 mm). The phantom was scanned at various oblique angles (0, 30, 45, 60 degree). Using in-house airway measurement software, central axis of oblique airway was determined by 3D thinning algorithm and CT image perpendicular to the axis was reconstructed. The luminal area, outer boundary, and wall thickness was measured by FWHM method at each image. Actual dimension of each tube and measured CT values on each CT data set was compared. Sharper reconstruction kernel, thicker image thickness, and larger oblique angle of airway axis results in decrease of measured wall thickness. There was internal interaction between imaging parameters and obliquity of airway on the accuracy of measurement. There was a threshold point of 1-mm wall thickness, below which the measurement failed to represent the change of real thickness. Even using the smaller FOV, the accuracy was not improved. Usage of standard kernel (B50f) and 0.75mm thickness results in the most accurate measurement results, which is independent of obliquity of airway. (Mean error: 0 Degree 0.067±0.05mm, 30 Degree 0.076±0.09, 45 Degree 0.074±0.09, 60 Degree 0.091±0.09). In this imaging parameters, there was no significant difference (paired t-test : p > 0.05) between actual measurement and each oblique angle measurement. The accuracy of airway wall measurement was strongly influenced by imaging parameters and obliquity of airway. For the accurate measurement, independent of obliquity, we recommend the CT images reconstructed with 0.75mm slice thickness and B50f or B30f with sharpening filter.

CT Findings of Diffuse Esophageal Spasm: Case Report

We report the CT findings of diffuse esophageal spasm (DES) in a patient with dysphagia. Although an uncommon condition, DES should be included in the differential diagnosis if relatively long and symmetric segmental esophageal wall thickening and an epiphrenic esophageal diverticulum are noted at CT.

The Role of HRCT in the Follow-Up Evaluation of Diffuse Interstitial Pulmonary Fibrosis

Background: Because of the power of HRCT to detect the minute changes in lung parenchyme and the advantage of noninvasiveness, it may be the ideal method of follow-up evaluation of the patients with diffuse interstitial pulmonary fibrosis. So the aim of the study is to find out whether the change of HRCT during the course of the disease can represent the change in symptom and pulmonary function test. Method: Thirteen patients with diagnosis of diffuse interstitial pulmonary fibrosis who had more than two times of HRCT during the course of disease were studied. The extent of the disease in HRCT was measured at three levels using image analyzer. The ralationship between the percent change in the disease extent in HRCT, symptom score, and pulmonary function tests were analysed. Results: The change of disease extent in HRCT has good correlation with the change in dyspnea and diffusion capacity(r=0.716, p=0.0012). But there was no correlation between the change of HRCT and FVC or TLC. Also significant inverse correlation was noted between the change in dyspnea and diffusion capacity(r=-0.707, p=0.0047). Conclusion: These data suggest that HRCT may be a good method of follow-up in diffuse interstitial pulmonary fibrosis.