-
Shinichi Ohta,
Norihisa Nitta,
Shobu Watanabe,
Yuki Tomozawa,
Akinaga Sonoda, Hideji Otani,
Keiko Tsuchiya,
Ayumi Nitta-Seko,
Atsuko Yamamoto,
Masashi Takahashi,
Kiyoshi Murata
[show abstract]
[hide abstract]
ABSTRACT: PURPOSE: To evaluate the embolic effect and degradability of gelatin microspheres (GMS) using various degrees of cross-linkage and particle sizes in rabbit renal artery embolization. METHODS: Four types of GMS were used, as follows: 2 types of cross-linkage and 2 types of particle size. Twenty-four rabbits (6 in each group) were used for the renal artery embolization. Renal angiography was performed before and after embolization of right renal artery. Follow-up renal angiography was performed 2 days (n = 2), 5 days (n = 2), and 15 days (n = 2) after embolization in each group, and then kidneys were removed for histopathological evaluation. Vascular areas of the angiography were measured by Image J software, and the reperfusion rate was calculated. In renal specimens, residual GMS were checked and the degree of degradation was classified according to a 4-point scale. RESULTS: The mean amounts of large- and small-particle-size GMS injected were 15.0 and 34.3 mg, respectively. Tissue necrosis was confirmed in each group; however, no difference was observed among groups. Renal reperfusion was observed more with small GMS than with large GMS. Renal reperfusion was also observed more with low cross-linked GMS than with high cross-linked GMS. In histopathological specimens, large GMS were confirmed in lobar artery, and small GMS were confirmed in lobular artery. Low cross-linked GMS completely degraded 15 days after embolization. In contrast, high cross-linked GMS were persistent 15 days after embolization. CONCLUSION: Degree of cross-linkage and particle size affected degradability and reperfusion.
CardioVascular and Interventional Radiology 12/2012; · 2.09 Impact Factor
-
Norihisa Nitta,
Shinichi Ohta,
Akinaga Sonoda,
Shobu Watanabe, Hideji Otani,
Yuki Tomozawa,
Ayumi Nitta-Seko,
Keiko Tsuchiya,
Kenichi Mukaisho,
Masashi Takahashi,
Kiyoshi Murata,
Yasuhiko Tabata
[show abstract]
[hide abstract]
ABSTRACT: Abstract Purpose: To evaluate the embolic effect and degradability of gelatin microspheres (GMS) and Gelpart particles (GPS) in dogs subjected to hepatic embolization. Material and methods: We subjected 20 beagles to embolization of the hepatic artery (HA) and assessed the embolic effects of GMS measuring 500 μm in dry and 1 mm in wet state and of 1-mm GPS, porous gelatin embolic particles. We obtained celiac angiographs before and immediately after embolization and two, 14, and 28 days later; the livers were histopathologically evaluated. Reperfusion of HA was assessed by inspecting the arterial branches. We checked the liver specimens for residual GMS, injury to surrounding tissues, and inflammatory changes, and investigated embolic formation in the HA. Results: The mean amount of injected GMS and GPS was 15.5 and 14.5 mg, respectively. While none of the dogs manifested HA reperfusion two days post-embolization, there was angiographic evidence of complete reperfusion 28 days after embolization. In all dogs, histopathological study showed arterial inflammatory changes and injury of surrounding tissues irrespective of the embolization materials used. These findings were pronounced on day 28 in dogs injected with GMS. Conclusion: There was no difference in the embolic effects of GMS and GPS nor in their degradability in dogs subjected to hepatic embolization.
Minimally invasive therapy & allied technologies: MITAT: official journal of the Society for Minimally Invasive Therapy 08/2012; · 1.33 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We followed the 4-week course of implanted VX2 tumors in rabbits and compared MRI and pathological findings to determine the appropriate time for starting therapy in animal liver tumor models.
We used 18 Japanese white rabbits. The VX2 liver tumor was harvested from one tumor-bearing rabbit and implanted in the liver of the other 17 rabbits. They were then sacrificed at 1 (n = 5), 2 (n = 3), 3 (n = 4), and 4 weeks (n = 5) after implantation and MRI study. Using MRI scans and/or pathological specimens of individual rabbits, we evaluated the tumor survival ratio, the major tumor axes, intrahepatic metastases, and peritoneal dissemination.
All tumor transplantations were successful. At 1 week, 56.25% of the implanted tumors were visualized on MRI scans. At 2 weeks or later, all transplanted rabbits were confirmed to be tumor-bearing on MRI scans. At 3 weeks after implantation, the tumor size was similar on MRI scans and in pathological specimens. There were no intra-hepatic metastases or peritoneal disseminations within 2 weeks of tumor transplantation.
We suggest that in studies of implanted VX2 models addressing the treatment of solid hepatic tumors, it may be prudent to start hepatic arterial embolization at 2 weeks after implantation.
Oncology 06/2011; 80(1-2):92-6. · 2.27 Impact Factor
-
Shobu Watanabe,
Norihisa Nitta,
Shinichi Ohta,
Akinaga Sonoda, Hideji Otani,
Yuki Tomozawa,
Ayumi Nitta-Seko,
Keiko Tsuchiya,
Toyohiko Tanka,
Masashi Takahashi,
Kiyoshi Murata
[show abstract]
[hide abstract]
ABSTRACT: This study was designed to evaluate the anti-tumor effects of miriplatin-lipidol and fine-powder cisplatin-lipiodol suspensions.
Assessment of the cytotoxicity of two drugs was performed: a soluble derivative of miriplatin (DPC) and fine-powder cisplatin. We randomly divided 15 rabbits with transplanted VX2 liver tumors into three equal groups. They were infused via the proper hepatic artery with a miriplatin-lipiodol suspension (ML), a fine-powder cisplatin-lipiodol suspension (CL), or saline (control) and the tumor growth rate was determined on MR images acquired before and 7 days after treatment. The concentration of platinum (PCs) in blood was assayed immediately, and 10, 30, and 60 min, and 24 h and 7 days after drug administration. Its concentration in tumor and surrounding normal liver tissues was determined at 7 days postadministration.
At high concentrations, fine-powder cisplatin exhibited stronger cytotoxicity than DPC. At low concentrations, both agents manifested weak cytotoxicity. While there was no difference between the tumor growth rate of the ML and the CL groups, the difference between the controls and ML- and CL-treated rabbits was significant. The blood PCs peaked at 10 min and then gradually decreased over time. On the other hand, no platinum was detected at any point after the administration of ML. There was no difference between the ML and CL groups in the PCs in tumor tissues; however, in normal hepatic tissue, the PCs were higher in ML- than CL-treated rabbits.
We confirmed the anti-tumor effect of ML and CL. There was no significant difference between the anti-tumor effect of ML and CL at 7 days postadministration.
CardioVascular and Interventional Radiology 05/2011; 35(2):399-405. · 2.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To examine the feasibility of quantitative high-resolution computed tomography (HRCT) findings to monitor the stage of bleomycin-induced pulmonary fibrosis in rabbits by correlating HRCT and pathologic scores and analyzing sequential changes on HRCT images using regional volume histograms.
Lung fibrosis was induced by injecting bleomycin intratracheally into 23 Japanese white rabbits. Rabbits were randomly separated into seven groups depending on follow-up period (12-hour, 24-hour, 3-day, 7-day, 14-day, 21-day, and 28-day). Four-row HRCT examinations were performed at any of the seven time points in each follow-up period and just after bleomycin administration in addition to pre-bleomycin administration as the baseline scan. Scores of consolidation, homogenous ground-glass opacity (GGO), inhomogeneous GGO, reticulolinear shadow, and honey-comb formation were recorded as ratio of affected area to total cross-section in four transaxial planes. Inflammatory and fibrous changes were scored histopathologically. Correlations between HRCT and pathologic findings were assessed. Sequential changes on HRCT images in areas with pathologically confirmed fibrosis were assessed on volume histograms of cubic regions of interest (ROI) using quantitative parameters.
Consolidation and inhomogeneous GGO exhibited fair correlations with inflammation scores (r = 0.273, P = .009, and r = 0.393, P < .001); reticulolinear shadow and inhomogeneous GGO had a fair and good correlation, respectively, with fibrous scores (r = 0.327, P = .001, and r = 0.579, P < .001). Inhomogeneous GGO was hardly detected on regional images at 21 and 28 days after bleomycin administration. As to mean computed tomography attenuation, skewness, and kurtosis, inhomogeneous GGO differed from reticulolinear shadow and consolidation.
Using appropriate ROI settings, quantitative assessment of inhomogeneous GGO with regional volume histograms enables us to monitor the progression of lung fibrosis by sequential observations.
Academic radiology 03/2011; 18(6):672-81. · 2.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The aim of this study was to compare the detectability of lung nodules on images obtained with a flat-panel detector computed tomography (FPD-CT) system and by chest radiographs (CXRs) using receiver-operating characteristic (ROC) analysis.
FPD-CT was conducted with the patients in the sitting position. For the CXR study, the patients stood erect. Our study population consisted of 26 individuals ranging in age from 50 to 83 years. The reference standard was based on the interpretations obtained by consensus of 2 radiologists on multidetector CT images for the presence or absence of nodules. Four other radiologists independently assessed and recorded the absence or presence of lung nodules and their location on FPD-CT and CXR images. ROC analysis was used to evaluate lung nodule detectability by both imaging modalities.
Two radiologists identified 34 nodules whose diameter was 5 to 42 mm (mean, 19.3 mm) in 23 of the 26 study participants on the multidetector CT images. Overall, analysis of variance for ROC analysis showed that FPD-CT was significantly better in detecting nodules than CXR (P=0.02). The estimated mean Az value was 0.9818±0.0083 with FPD-CT and 0.7610±0.0908 with CXR. The sensitivity for nodule detection on FPD-CT and CXR images was 79.4% and 33.8%, respectively.
The detectability of pulmonary nodules was better on images of FPD-CT than on CXRs.
Journal of thoracic imaging 02/2011; 27(1):51-7. · 1.42 Impact Factor
-
Keiko Tsuchiya,
Norihisa Nitta,
Akinaga Sonoda,
Ayumi Nitta-Seko,
Shinichi Ohta, Hideji Otani,
Masashi Takahashi,
Kiyoshi Murata,
Katsutoshi Murase,
Satoshi Nohara,
Kenichi Mukaisho
[show abstract]
[hide abstract]
ABSTRACT: The biodynamics of ultrasmall and small superparamagnetic iron oxide (USPIO and SPIO, respectively) particles that were injected intraperitoneally into 36 C57BL/6 mice were investigated chronologically. Their distribution was studied histologically at six time points by measuring iron-positive areas (μm²) in organ sections stained with Prussian blue. The uptake of the differently sized particles was also compared by cultured murine macrophages (J774.1). Iron-positive areas in the liver were significantly larger in the mice injected with USPIO than those injected with SPIO at the first three time points (P < 0.05). The amount of USPIO in the lung parenchyma around the airway was larger than that of SPIO at four time points (P < 0.05); distribution to the lymph nodes was not significantly different. The amount of iron was significantly larger in SPIO- than USPIO-treated cultured cells (P < 0.05). In conclusion, it is suggested that intra peritoneally injected USPIO particles could be used more quickly than SPIO to make Kupffer images of the liver and that both agents could help get lymph node images of similar quality.
International Journal of Nanomedicine 01/2011; 6:1587-94. · 3.13 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To compare flat-panel detector (FPD) radiography and film-screen (FS) radiography in detectability of faint shadows documented as ground-glass attenuation (GGA) areas in images of computed tomography (CT).
Study population was comprised of 50 patients who underwent FS and another 50 patients who underwent FPD. Standard of reference (SOR) was determined on the basis of area of GGA in all cross-sections of CT, in terms of GGA extent and presence or absence of GGA in each trisected lung fields (GGA distribution). Eight radiologists assessed the GGA extent with the 5-grade scale and the GGA distribution. Inter-observer variances of the GGA extents and distributions, degree of divergences and correspondence in the GGA extent and distributions with SOR, were compared between the FS and FPD by the jackknife method and Fisher's exact test.
Inter-observer variance in the GGA extent and distribution were slightly larger in the FS than in the FPD. The GGA extent scale corresponded with SOR in the FS statistically significantly better (p=0.001), as the correct ratio was 0.428 in the FS and 0.310 in the FPD. Divergence in the GGA extent scale with SOR was smaller in the FS, as average kappa pseudo-value of Kendall's rank correlation coefficient was 0.474 in the FS and 0.433 in the FPD.
These results indicate that some lesions of GGA documented in CT may not be reflected and are difficult to be detected in chest X-ray radiographs with the FPD.
European journal of radiology 06/2009; 75(3):384-90. · 2.65 Impact Factor
-
Yukihiro Nagatani,
Norihisa Nitta,
Masashi Takahashi,
Noriaki Tezuka,
Yasutaka Nakano,
Mitsuru Ikeda,
Yuki Kirino,
Keiji Hashimoto, Hideji Otani,
Yoko Murakami,
Kiyoshi Murata
[show abstract]
[hide abstract]
ABSTRACT: The aim of this study was to introduce a prototype cone-beam computed tomography system equipped with a flat panel detector (FPD-CT system) and measure its radiation dose and spatial and lowcontrast resolution.
A patient was rotated in a sitting position, and cone beam data were acquired with the flat panel detector from a fixed X-ray tube. Absorbed dose, spatial and low-contrast resolution, and variation in the CT attenuation value were assessed quantitatively in the acrylic phantom. The visibility of normal blood vessels in clinical images of seven patients was analyzed qualitatively by five board-certified radiologists. These quantitative and qualitative data were compared between the FPD-CT system and multidetector row CT (MDCT).
Minimal low-contrast sensitivity and a moderate spatial resolution were demonstrated in images of central lung fields acquired by FPD-CT. The absorbed dose in the FPD-CT system decreased to approximately 2.5% of the dose in the MDCT system.
Considering crossover structures in normal blood vessels and bronchi in the central areas of lung fields, this result implies that fairly acceptable spatial resolution can be realized with FPD-CT for detection and frequent follow-up of pulmonary abnormalities in the central lung fields.
Radiation Medicine 01/2009; 26(10):627-35.
-
[show abstract]
[hide abstract]
ABSTRACT: To determine the feasibility of assessment of arterial stiffness with multiphase analysis of data sets of retrospectively electrocardiogram (ECG)-gated multidetector row computed tomography (MDCT) coronary angiography by comparing wall stiffness of the descending aorta between patients under chronic hemodialysis and age-matched controls undergoing imaging for by-pass graft.
We retrospectively assessed 33 patients composed of 10 hemodialysis patients and 23 age-matched control subjects, who underwent MDCT to evaluate the coronary arterial lesions and pulse wave velocity (PWV) measurement. Scan data were reconstructed at 25 phases between 0% and 96% of the R-R intervals with an increment of 4%. Pixel-based measurements of arterial dimensions were performed at 1 cross-section of the descending aorta in a transaxial plane including the aortic valve at its widest. Aortic distensibility (AD) was calculated as follows: AD = (maximal dimension -- minimal dimension)/minimal dimension x pulse pressure. Comparison in the AD was performed between the hemodialysis patients and control subjects. Correlation between the AD and PWV were assessed separately in the patients under hemodialysis and age-matched controls.
AD was significantly smaller in patients under hemodialysis than in age-matched controls. The square of PWV correlated better with the inverse of the AD in the control subjects compared to patients on hemodialysis.
Multiphase analysis in ECG-gated MDCT enables us to assess stiffness of the descending aorta objectively and noninvasively.
Investigative Radiology 04/2008; 43(3):195-201. · 4.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The term 'emphysema' is generally used in a morphological sense, and therefore imaging modalities have an important role in diagnosing this disease. In particular, high resolution computed tomography (HRCT) is a reliable tool for demonstrating the pathology of emphysema, even in subtle changes within secondary pulmonary lobules. Generally, pulmonary emphysema is classified into three types related to the lobular anatomy: centrilobular emphysema, panlobular emphysema, and paraseptal emphysema. In this pictorial review, we discuss the radiological--pathological correlation in each type of pulmonary emphysema. HRCT of early centrilobular emphysema shows an evenly distributed centrilobular tiny areas of low attenuation with ill-defined borders. With enlargement of the dilated airspace, the surrounding lung parenchyma is compressed, which enables observation of a clear border between the emphysematous area and the normal lung. Because the disease progresses from the centrilobular portion, normal lung parenchyma in the perilobular portion tends to be preserved, even in a case of far-advanced pulmonary emphysema. In panlobular emphysema, HRCT shows either panlobular low attenuation or ill-defined diffuse low attenuation of the lung. Paraseptal emphysema is characterized by subpleural well-defined cystic spaces. Recent topics related to imaging of pulmonary emphysema will also be discussed, including morphometry of the airway in cases of chronic obstructive pulmonary disease, combined pulmonary fibrosis and pulmonary emphysema, and bronchogenic carcinoma associated with bullous lung disease.
International Journal of COPD 02/2008; 3(2):193-204.
