Hideji Otani

Imaging of pulmonary emphysema: A pictorial review

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.

Atherosclerotic imaging using 4 types of superparamagnetic iron oxides: new possibilities for mannan-coated particles.

PURPOSE We used magnetic resonance imaging (MRI) and histologic techniques to compare the uptake by the rabbit atherosclerotic wall of 4 types of superparamagnetic iron oxide (SPIO) particles, i.e. SPIO, mannan-coated SPIO (M-SPIO), ultrasmall SPIO (USPIO), and mannan-coated USPIO (M-USPIO). MATERIALS AND METHODS All experimental protocols were approved by our institutional animal experimentation committee. We intravenously injected 12 Watanabe heritable hyperlipidemic rabbits with one of the 4 types of SPIO (0.8 mmol Fe/kg). Two other rabbits served as the control. The rabbits underwent in vivo contrast-enhanced magnetic resonance angiography (MRA) before- and 5 days after these injections; excised aortae were subjected to in vitro MRI. In the in vivo and in vitro studies we assessed the signal intensity of the vessels at identical regions of interest (ROI) and calculated the signal-to-noise ratio (SNR). For histologic assessment we evaluated the iron-positive regions in Prussian blue-stained specimens. RESULTS There were significant differences in iron-positive regions where M-USPIO>USPIO, M-SPIO>SPIO, USPIO>SPIO (p<0.05) but not between M-USPIO and M-SPIO. The difference between the pre- and post-injection SNR was significantly greater in rabbits treated with M-USPIO than USPIO and in rabbits injected with M-SPIO than SPIO (p<0.05). On in vitro MRI scans SNR tended to be lower in M-USPIO- and M-SPIO- than USPIO- and SPIO-treated rabbits (p<0.1). CONCLUSION Histologic and imaging analysis showed that mannan-coated SPIO and USPIO particles were taken up more readily by the atherosclerotic rabbit wall than uncoated SPIO and USPIO.

Histological study of the biodynamics of iron oxide nanoparticles with different diameters.

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.

Enhanced Intestinal Motility during Oral Glucose Tolerance Test after Laparoscopic Sleeve Gastrectomy: Preliminary Results Using Cine Magnetic Resonance Imaging.

Background Enhanced secretion of glucagon-like peptide-1 (GLP-1) has been suggested as a possible mechanism underlying the improvement in type 2 diabetes mellitus (T2DM) after laparoscopic sleeve gastrectomy (LSG). However, the reason for enhanced GLP-1 secretion during glucose challenge after LSG remains unclear because LSG does not include intestinal bypass. In this study, we focused on the effects of LSG on GLP-1 secretion and intestinal motility during the oral glucose tolerance test (OGTT) using cine magnetic resonance imaging (MRI) before and 3 months after LSG. Methods LSG was performed in 12 obese patients with a body mass index >35 kg/m2. Six patients had T2DM. OGTT was performed before and 3 months after the surgery. Body weight, hemoglobin A1c (HbA1c), and GLP-1 levels during OGTT were examined, and intestinal motility during OGTT was assessed using cine MRI. Results Body weight was significantly decreased after surgery in all the cases. HbA1c was markedly decreased in all the diabetic subjects. In all cases, GLP-1 secretion during OGTT was enhanced and cine MRI showed markedly increased intestinal motility at 15 and 30 min during OGTT after LSG. Conclusions LSG leads to accelerated intestinal motility and reduced intestinal transit time, which may be involved in the mechanism underlying enhanced GLP-1 secretion during OGTT after LSG.

Time-course studies of implanted rabbit VX2 liver tumors to identify the appropriate time for starting hepatic arterial embolization in animal models.

Purpose: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.

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.

Evaluation of the embolic effect and degradability of gelatin microspheres and gelpart particles

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.

Asialoerythropoietin ameliorates bleomycin-induced acute lung injury in rabbits by reducing inflammation.

Acute lung injury, a critical illness characterized by acute respiratory failure with bilateral pulmonary infiltrates, remains unresponsive to current treatments. The condition involves injury to the alveolar capillary barrier, neutrophil accumulation and the induction of proinflammatory cytokines followed by lung fibrosis. In the present study, a rabbit model of bleomycin-induced acute lung injury was established to examine the effects of asialoerythropoietin (AEP), an agent with tissue-protective activities, on pulmonary inflammation. Six Japanese white rabbits were randomly divided into two equal groups. Acute lung injury was induced in all rabbits by intratracheally injecting bleomycin. The control group was injected with bleomycin only; the experimental (AEP) group was injected intravenously with AEP (80 μg/kg) prior to the bleomycin injection. Computed tomography (CT) studies were performed seven days later. The CT inflammatory scores of areas exhibiting abnormal density and the pathological inflammatory scores were recorded as a ratio on a 7×7 mm grid. The CT and pathological inflammatory scores were significantly different between the control and AEP groups [122±10 and 16.3±1.5 (controls) vs. 71±8.5 and 9.7±1.4 (AEP), respectively; P<0.01]. Thus, the present study revealed that AEP prevents bleomycin-induced acute lung injury in rabbits.

Flat-panel detector computed tomography imaging: observer performance in detecting pulmonary nodules in comparison with conventional chest radiography and multidetector computed tomography.

Purpose 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. Materials and Methods 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. Results 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. Conclusion The detectability of pulmonary nodules was better on images of FPD-CT than on CXRs.

Ultra-low-dose computed tomography system with a flat panel detector: assessment of radiation dose reduction and spatial and low contrast resolution

PurposeThe 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.Materials and methodsA 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).ResultsMinimal 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.ConclusionConsidering 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.