Shuzo Kanasaki

CT Diagnosis of Acute Mesenteric Ischemia from Various Causes

OBJECTIVE Acute mesenteric ischemia can be caused by various conditions such as arterial occlusion, venous occlusion, strangulating obstruction, and hypoperfusion associated with nonocclusive vascular disease, and the CT findings vary widely depending on the cause and underlying pathophysiology. The aim of this article is to review the CT appearances of acute mesenteric ischemia in various conditions. CONCLUSION Recognition of characteristic CT appearances and the variations associated with each cause may help in the accurate interpretation of CT in the diagnosis of mesenteric ischemia.

Gastrointestinal tract perforation: CT diagnosis of presence, site, and cause

Gastrointestinal tract perforation is an emergent condition that requires prompt surgery. Diagnosis largely depends on imaging examinations, and correct diagnosis of the presence, level, and cause of perforation is essential for appropriate management and surgical planning. Plain radiography remains the first imaging study and may be followed by intraluminal contrast examination; however, the high clinical efficacy of computed tomographic examination in this field has been well recognized. The advent of spiral and multidetector-row computed tomographic scanners has enabled examination of the entire abdomen in a single breath-hold by using thin-slice sections that allow precise assessment of pathology in the alimentary tract. Extraluminal air that is too small to be detected by conventional radiography can be demonstrated by computed tomography. Indirect findings of bowel perforation such as phlegmon, abscess, peritoneal fluid, or an extraluminal foreign body can also be demonstrated. Gastrointestinal mural pathology and associated adjacent inflammation are precisely assessed with thin-section images and multiplanar reformations that aid in the assessment of the site and cause of perforation.

Assessment of small bowel motility function With cine-MRI using balanced steady-state free precession sequence

To evaluate the use of cine‐magnetic resonance imaging (MRI) with a steady‐state free precession sequence to monitor and assess small bowel motility.

Polyorethaoe-covered nitinol strecker stents as primary palliative treatment of malignant biliary obstruction

AbstractPurpose: To evaluate the clinical efficacy of the polyure-thane-covered Nitinol Strecker stent in the treatment of patients with malignant biliary obstruction. Methods: Twenty-three covered stents produced by us were placed in 18 patients with malignant biliary obstruction. Jaundice was caused by cholangiocarcinoma (n=5), pancreatic Cancer (n=6), gallbladder Cancer (n=4), metastatic lymph nodes (n=2), and tumor of the papilla (n=1). Resulrs: The mean patency period of the Stents was 37.5 weeks (5–106 weeks). Recurrent obstructive jaundice occurred in two patients (11%). Adequate biliary drainage over 50 weeks or until death was achieved in 17 of 18 patients (94.4%). Late cholangitis was observed in two patients whose stents bridged the ampulla of Vater. Other late severe complications were not encountered. Conclusion: Although more study is necessary, our results suggest the clinical efficacy of our covered Nitinol Strecker stent in the management of obstructive jaundice caused by malignant diseases.

Preliminary study on statistical shape model applied to diagnosis of liver cirrhosis

In computational anatomy, statistical shape model (SSM) is used for the quantitative evaluation of variations in the shapes of different organs. This paper focuses on the construction of a SSM of the liver and its application to computer-assisted diagnosis of cirrhosis. We prove the potential application of SSMs in the classification of normal and cirrhotic livers. In constructing a SSM of the liver, we first normalize volume data followed by the construction of the model using principal component analysis. The coefficients of the model are used as indicators of liver pathology. The effectiveness of the constructed model is evaluated by the classification accuracy of both normal and abnormal data.

Computer-Aided Diagnosis and Quantification of Cirrhotic Livers Based on Morphological Analysis and Machine Learning

It is widely known that morphological changes of the liver and the spleen occur during the clinical course of chronic liver diseases. In this paper, we proposed a morphological analysis method based on statistical shape models (SSMs) of the liver and spleen for computer-aided diagnosis and quantification of the chronic liver. We constructed not only the liver SSM but also the spleen SSM and a joint SSM of the liver and the spleen for a morphologic analysis of the cirrhotic liver in CT images. The effective modes are selected based on both its accumulation contribution rate and its correlation with doctors opinions (stage labels). We then learn a mapping function between the selected mode and the stage of chronic liver. The mapping function was used for diagnosis and staging of chronic liver diseases.

A combination of cisplatin-eluting gelatin microspheres and flavopiridol enhances anti-tumour effects in a rabbit VX2 liver tumour model.

The aim of this study was to investigate whether the combination of cisplatin-eluting gelatin microspheres (GMSs) and flavopiridol enhances anti-tumour effects in a rabbit VX2 liver tumour model. Tumour-bearing rabbits (n = 21) were divided into five groups and infused from the proper hepatic artery. Group 1 (n = 5) received cisplatin-eluting GMSs (1 mg kg(-1)) and flavopiridol (3 mg kg(-1)), group 2 (n = 5) cisplatin-eluting GMSs alone (1 mg kg(-1)), Group 3 (n = 5) flavopiridol (3 mg kg(-1)), Group 4 (n = 3) GMSs alone (1 mg kg(-1)), and Group 5 (n = 3) was the control group receiving physiological saline (1 ml kg(-1)). On days 0 and 7 after procedures the liver tumour volume was measured using a horizontal open MRI system and the relative tumour volume growth rates for 7 days after treatment were calculated. On T(1) weighted images, the tumours were visualised as circular, low-intensity areas just below the liver surface. After treatment, the signals remained similar. The relative tumour volume growth rate for 7 days after treatment was 54.2+/-22.4% in Group 1, 134.1+/-40.1% in Group 2,166.7+/-48.1% in Group 3, 341.8+/-8.6% in Group 4 and 583.1+/-46.9% in Group 5; the growth rate was significantly lower in Group 1 than the other groups (p<0.05). We concluded that in our rabbit model of liver tumours the combination of cisplatin-eluting GMSs and flavopiridol was effective.

Imaging findings of primary hepatic carcinoid tumor with an emphasis on MR imaging: case study

Carcinoid tumors are slow-growing tumors originating in the neuroendocrine cells, and occur most frequently within the gastrointestinal tract. Although the liver is the most common site for metastatic carcinoid tumors, primary hepatic carcinoid tumors are exceedingly rare and reports of the imaging findings have been very scarce. We herein report imaging findings with an emphasis on magnetic resonance imaging in two cases of primary hepatic carcinoid tumors. In both cases, the tumors showed cystic areas with hemorrhagic components and early enhanced solid areas.

Automated assessment of small bowel motility function based on three-dimensional zero-mean normalized cross correlation

In this paper, we propose an automated method for assessment of small bowel contraction movement based on a three-dimensional zero-mean normalized cross correlation method (3D-ZNCC) with cine-MRI. The correlation value between frames is proportional to area change of the small bowel and the temporal area change can be used as a measure of the small bowel contraction movement. In the conventional two-dimensional zero-mean normalized correlation (2D-ZNCC) method, only frame A and frame B are used for calculation of correlation between frame A and frame B. Since a complex shape change of the intestine is irregular, it was difficult to detect contraction movement. In order to solve this problem, we propose to use 3D ZNCC, in which sequence frames are used for correlation calculations instead of single frame. Since not only spatial changes, but also temporal changes are included, we can detect the contraction movement correctly. Experimental results show that our method is better than conventional method.

Efficient shape representation and statistical shape modeling of the liver using spherical harmonic functions (SPHARM)

In the field of medical image analysis, the three-dimensional (3-D) shape representation and modeling of anatomic structures using only a few parameters is an important issue, and can be applied to computer assisted diagnosis, surgical simulations, visualization, and many other medical applications. In this paper, we show that the 3D anatomical structure such as the liver can be represented by a few coefficients of spherical harmonic functions (SPHARM). We also propose to use SPHARM based shape representation for statistical shape modeling. Since the dimension of SPHARM based shape representation vector is much lower than the conventional shape representation using coordinates of surface points, our proposed method can be used for small number of training samples and enhance the computation cost.