Shigeyuki Yoshida

Three-dimensional multi-scale line filter for segmentation and visualization of curvilinear structures in medical images

This paper describes a method for the enhancement of curvilinear structures such as vessels and bronchi in three-dimensional (3-D) medical images. A 3-D line enhancement filter is developed with the aim of discriminating line structures from other structures and recovering line structures of various widths. The 3-D line filter is based on a combination of the eigenvalues of the 3-D Hessian matrix. Multi-scale integration is formulated by taking the maximum among single-scale filter responses, and its characteristics are examined to derive criteria for the selection of parameters in the formulation. The resultant multi-scale line-filtered images provide significantly improved segmentation and visualization of curvilinear structures. The usefulness of the method is demonstrated by the segmentation and visualization of brain vessels from magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), bronchi from a chest CT, and liver vessels (portal veins) from an abdominal CT.

3D Multi-scale line filter for segmentation and visualization of curvilinear structures in medical images

This paper describes a method for the enhancement of curvilinear structures like vessels and bronchi in 3D medical images. We develop a line-enhancement filter based on the eigenvalues of Hessian matrix aiming at both the discrimination of line structures from other structures and the recovery of original line structures from corrupted ones. The multi-scale responses of the line filters are integrated based on the equalization of noise level at each scale. The resulted multi-scale line filtered images provide significantly improved segmentation of curvilinear structures. The line-filtered images are also useful for the direct visualization of curvilinear structures by combining with a volume rendering technique even from conventional MR images. We show the usefulness of the method through the segmentation and visualization of vessels from MRA and MR images, and bronchi from CT images.

Invasive and noninvasive thymoma: distinctive CT features.

Purpose The purpose of this work was to evaluate the CT features of thymoma and to determine the most helpful findings in differentiating invasive from noninvasive thymoma. Method The CT scans from 27 patients with invasive thymoma and 23 with noninvasive thymoma were independently assessed by two observers without knowledge of their invasiveness. The presence and distribution of various CT findings were independently analyzed. Results Invasive thymomas were more likely to have lobulated (16/27, 59%) or irregular (6/27, 22%) contours than noninvasive thymomas (8/23, 35% and 1.5/23, 6%, respectively) (p < 0.05). Invasive thymomas had a higher prevalence of low attenuation areas within the tumor (16/27, 60%) than noninvasive thymomas (5/23, 22%) (p < 0.001) as well as foci of calcification (14.5/27, 54% vs. 6/23, 26%; p < 0.01). Conclusion The presence of lobulated or irregular contour, areas of low attenuation, and multifocal calcification is suggestive of invasive thymoma.

Adaptive statistical iterative reconstruction technique for pulmonary CT: image quality of the cadaveric lung on standard- and reduced-dose CT.

RATIONALE AND OBJECTIVES To evaluate thin-section computed tomography (CT) images of the lung reconstructed using adaptive statistical iterative reconstruction (ASIR) on standard- and reduced-dose CT. MATERIALS AND METHODS Eleven cadaveric lungs were scanned by multidetector-row CT with two different tube currents (standard dose, 400 mA; reduced dose, 10 mA). The degree of ASIR was classified into six different levels: 0% (non-ASIR), 20%, 40%, 60%, 80%, and 100% (maximum-ASIR). The ASIR (20%, 60%, and 100%) images were compared with the ASIR (0%) images and assessed visually by three independent observers for image quality using a 7-point scale. The evaluation items included abnormal CT findings, normal lung structures, and subjective visual noise. The median scores assigned by the three observers were analyzed statistically. Quantitative noise was calculated by measuring the standard deviation in a circular region of interest on each selected image of ASIR (0%-100%). RESULTS On standard-dose CT, the overall image quality significantly improved with increasing degree of ASIR (P ≤ .009, Wilcoxon signed-ranks test with Bonferroni correction). As ASIR increased, however, intralobular reticular opacities and peripheral vessels tended to be obscure. On reduced-dose CT, the overall image quality of ASIR (100%) was significantly better than that of ASIR (20%) (P ≤ .009). As ASIR increased, however, intralobular reticular opacities tended to be obscure. Using ASIR significantly reduced subjective and quantitative image noise on both standard- and reduced-dose CT (P < .001, Bonferroni/Dunns method). CONCLUSION ASIR improves the image quality by decreasing image noise. Maximum-ASIR may be needed for improving image quality on highly reduced-dose CT. However, excessive ASIR may obscure subtle shadows.

Comparison of High Resolution Ct Findings of Sarcoidosis, Lymphoma, and Lymphangitic Carcinoma: Is There Any Difference of Involved Interstitium?

PURPOSE The purpose of this study was to determine distinguishing features of three diseases that are distributed along the lymphatics. METHOD CT scans of 40 patients with lymphangitic carcinomatosis, 41 with sarcoidosis, and 44 with malignant lymphoma were retrospectively reviewed. We evaluated the degree of involvement of the interlobular septa, bronchovascular structures, subpleural interstitium, and other CT findings. RESULTS The number of thickened interlobular septa and the extent of involvement of the subpleural interstitium in lymphangitic carcinomatosis were higher than those in sarcoidosis and malignant lymphoma (p<0.0001). Nodules of >1 cm in diameter were more often seen in malignant lymphoma (41.0%) than in the other two diseases (p < 0.001). Bilateral distribution was more common in sarcoidosis (100%) than in the others (p<0.001). CONCLUSION The major difference among lymphangitic carcinomatosis, sarcoidosis, and malignant lymphoma is the greater involvement of the interlobular septa and subpleural interstitium in lymphangitic carcinomatosis than in either sarcoidosis or malignant lymphoma.

Commercially Available Computer-Aided Detection System for Pulmonary Nodules on Thin-Section Images Using 64 Detectors-Row CT: Preliminary study of 48 cases

RATIONALE AND OBJECTIVES Most studies of computer-aided detection (CAD) for pulmonary nodules have focused on solid nodule detection. The aim of this study was to evaluate the performance of a commercially available CAD system in the detection of pulmonary nodules with or without ground-glass opacity (GGO) using 64-detector-row computed tomography compared to visual interpretation. MATERIALS AND METHODS Computed tomographic examinations were performed on 48 patients with existing or suspicious pulmonary nodules on chest radiography. Three radiologists independently reported the location and pattern (GGO, solid, or part solid) of each nodule candidate on computed tomographic scans, assigned each a confidence score, and then analyzed all scans using the CAD system. A reference standard was established by a consensus panel of different radiologists, who found 229 noncalcified nodules with diameters > or = 4 mm. True-positive and false-positive results and confidence levels were used to generate jackknife alternative free-response receiver-operating characteristic plots. RESULTS The sensitivity of GGO for 3 radiologists (60%-80%) was significantly higher than that for the CAD system (21%) (McNemars test, P < .0001). For overall and solid nodules, the figure-of-merit values without and with the CAD system were significantly different (P = .005-.04) on jackknife alternative free-response receiver-operating characteristic analysis. For GGO and part-solid nodules, the figure-of-merit values with the CAD system were greater than those without the CAD system, indicating no significant differences. CONCLUSION Radiologists are significantly superior to this CAD system in the detection of GGO, but the CAD system can still play a complementary role in detecting nodules with or without GGO.

Respiratory change in size of honeycombing: inspiratory and expiratory spiral volumetric CT analysis of 97 cases.

PURPOSE The purpose of this study was twofold: to evaluate the change in size of honeycomb cysts with respiration using inspiratory-expiratory spiral volumetric CT (I-E SVCT) and to establish the pathologic basis of this change. METHOD Ninety-seven patients, who had honeycombing associated with end-stage pulmonary fibrosis on end-inspiratory 1 to 2 mm collimation high-resolution CT (HRCT), underwent I-E SVCT (3 mm collimation, pitch 1, breath-hold time 20 s, reconstruction interval 1 mm, FOV 16-20 cm, high frequency algorithm). I-E SVCT scans were assessed on images obtained in the transverse plane and volumetric sagittal, coronal, and oblique reformations. The histologic findings were assessed in four inflated and fixed lungs that showed honeycombing at postmortem HRCT. RESULTS In 63 patients (65%), a small percentage of the cysts did not change in size at end-expiration, while in the remaining patients, all the cysts decreased in size. Assessment of volumetric multiplanar reformations showed that cysts that decreased in size during exhalation communicated with airways and represented bronchiolectasis rather than true cysts, while the other cysts did not communicate with the airways. Similar findings were found in pathologic specimens. CONCLUSION The majority of, but not all, honeycomb cysts seen on HRCT represent dilated bronchioles that communicate with the proximal airways and change in size with respiration.

Computed Tomography Values Calculation and Volume Histogram Analysis for Various Computed Tomographic Patterns of Diffuse Lung Diseases

Objective: The aim of this study was to determine the computed tomography (CT) values of various pulmonary abnormalities in cubic region of interest (ROI) and square ROI and evaluate the CT findings by histogram analysis in the ROI. Methods: The study included 89 patients with the following 8 pulmonary CT patterns: normal lung, ground-glass attenuation, fine reticular opacity, coarse reticular opacity, honeycombing, airspace consolidation, nodular opacity, and emphysema. Cubic and square ROIs were selected in each CT pattern, and 5 values (contrast, variance, entropy, skewness, and kurtosis) were calculated. Results: In the histogram of ground-glass attenuation, fine reticular opacity, and coarse reticular opacity, peaks had moved to the right compared with the normal lung. Only emphysema had higher contrast and lower entropy than the normal lung (P < 0.001). The other abnormalities had lower contrast and higher entropy than the normal lung. Conclusions: In conclusion, the shapes of histograms were characteristic of various abnormalities of the lung, and the values reflected the histogram quantitatively.

Colonic lipoma with florid vascular proliferation and nodule-aggregating appearance related to repeated intussusception.

A unique case of repeatedly intussuscepted colonic lipoma mimicking an epithelial tumor in a 50‐year‐old man is reported. The tumor was located in the ascending colon and was approximately 5 cm in diameter. Colonoscopic and barium‐enema examinations suggested a huge epithelial tumor because of its nodule‐aggregating appearance. In contrast, computed tomography examination showed a fatty element in the core of the lesion. The biopsy specimens suggested a primary angiomatous lesion because of its pronounced vascular proliferation. Because the presumed diagnoses based on the examinations were different, the preoperative diagnosis was not confirmed. The tumor was composed of intramural lipoma with a multiple polypoid mucosa overlay. This lesion was unique in that the lipoma appeared to be within the muscularis propria and the multiple polypoid appearance of its covering mucosa. The mucosal changes including florid vascular proliferation, fibromuscular obliteration and epithelial regeneration suggested a reparative process, with ischemic damage due to the effects of intussusception being the most likely event. It should be kept in mind that even a simple lipoma can have a unique appearance reminiscent of epithelial tumor when it repeatedly experiences intussusception.

3-Dimensional Images Processed by Multislice CT was Efficacious to Determine the Suitable Hepatectomy for a Case of Liver Metastasis of Colon Cancer.

マルチスライスCTより作成した3次元画像が術式決定に有用であった大腸癌肝転移の1例を報告する. 症例は63歳の男性. 他院で下行結腸癌の手術を受け経過観察中, 肝転移を指摘され当院を受診した. 肝CT水平断像で腫瘍はS3を中心にS4に進展しており, 左葉切除が必要であると考えられた.CT肝動脈造影検査で左肝動脈は左胃動脈より分枝し, これが腫瘍に流入していることが示された.CT門脈造影検査では, 腫瘍は門脈P3本幹と離れていることが示された. 以上より左肝動脈を切離の後, 門脈P3本幹を温存したS3部分切除が妥当であると判断され, これらの画像に推奨された手術が可能であった. 近年, 低侵襲で多くの情報が得られるマルチスライスCTが普及しつつあるが, 肝臓外科領域での有用性についてはあまり報告されていない. 本症例に肝切除を行うに際して, マルチスライスCT は適切な術式の決定に有用であった.