Norihisa Nitta

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.

The first trial of phase contrast imaging for digital full-field mammography using a practical Molybdenum x-ray tube

Rationale and Objectives:The image quality of a newly developed full-field digital phase contrast mammography (PCM) system and of a conventional screen-film (SF) mammography system were compared via images of a phantom and receiver operating characteristic (ROC) analysis of clinical images. Methods:Magnified (1.75×) PCM images were scanned (sampling rate, 43.75 &mgr;m) and then reduced to original-sized, 25-micron pixel images printed on photothermographic film. Along with corresponding SF images, the phantom images were evaluated subjectively, and the clinical images of 38 patients were subjected to ROC analysis of mass and microcalcification. Results:In the image quality of a phantom, the PCM exceeded the SF. In both mass and microcalcification, the ROC analysis Az values of the PCM clinical images surpassed those of the SF images. Conclusion:The PCM provides better images than the SF. Clinical trials suggest superior detection of both mass and microcalcification by full-field digital PCM over conventional SF mammography.

MR Imaging of the Normal Appendix and Acute Appendicitis

To describe the MR appearance of the normal appendix and the MR imaging characteristics of acute appendicitis with correlation to pathological severity.

Asialoerythropoietin Prevents Contrast-Induced Nephropathy

Strategies to prevent contrast-induced nephropathy (CIN) are suboptimal. Erythropoietin was recently found to be cytoprotective in a variety of nonhematopoietic cells, so it was hypothesized that the nonhematopoietic erythropoietin derivative asialoerythropoietin would prevent CIN. Nephropathy was induced in rats by injection of the radiocontrast medium Ioversol in addition to inhibition of prostaglandin and nitric oxide synthesis. Administration of a single dose of asialoerythropoietin before the induction of nephropathy significantly attenuated the resulting renal dysfunction and histologic renal tubular injury. Contrast-induced apoptosis of renal tubular cells was inhibited by asialoerythropoietin both in vivo and in vitro, and this effect was blocked by a Janus kinase 2 (JAK2) inhibitor in vitro. Furthermore, phospho-JAK2/signal transducer and activator of transcription 5 (STAT5) and heat-shock protein 70 increased after injection of asialoerythropoietin, suggesting that the effects of asialoerythropoietin may be mediated by the activation of the JAK2/STAT5 pathway. Overall, these findings suggest that asialoerythropoietin may have potential as a new therapeutic approach to prevent CIN given its ability to preserve renal function and directly protect renal tissue.

Diaphragmatic motion in the sitting and supine positions: Healthy subject study using a vertically open magnetic resonance system

To determine the postural difference of diaphragmatic motion between the sitting and supine positions.

Newly Developed Biodegradable Stents for Benign Gastrointestinal Tract Stenoses: A Preliminary Clinical Trial

We developed an Ultraflex-type stent by knitting polylactic acid monofilaments. The purpose of this study was to evaluate the stent’s clinical usefulness for treating benign stenoses in the gastrointestinal tract. The radial force of the biodegradable stent was compared with those of commercially available metallic stents. The measured radial force of the new biodegradable stent was higher than that of commercially available metallic stents. The biodegradable stents were applied in 2 patients with benign gastrointestinal stenoses. The first patient was a 19-year-old female with esophageal stenosis, due to drinking of caustic potash in an attempt to commit suicide. The second patient was a 75-year-old male who had a stenosis at the anastomotic site after esophageal cancer resection. In both cases, the placement of the stent was performed successfully, and the patients’ complaints improved immediately after stent placement. There were no complications during stent placement. The stenosis had not recurred at the six-month follow-up examination. In conclusion, the newly developed biodegradable stents were useful in treating benign stenoses of the alimentary tract.

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.

Degradable Gelatin Microspheres as an Embolic Agent: an Experimental Study in a Rabbit Renal Model

Objective To investigate the basic characteristics of degradable gelatin microspheres (GMSs), including their embolic behavior and degradation periods when they are used as embolic materials in the renal arteries of rabbit models. Materials and Methods Based on the GMS particle size, 24 kidneys were divided into 3 groups of eight kidneys, and each group was embolized with a different GMS particle size (group 1:35-100 µm, group 2: 100-200 µm, and group 3: 200-300 µm). From each group, two rabbits were sacrificed immediately after embolization (day 0), and a pair of rabbits from each group underwent an angiogram and were sacrificed on days 3, 7, and 14, respectively, after embolization. The level of arterial occlusion, the pathological changes in the renal parenchyma, and the degradation of the GMSs were evaluated angiographically and histologically. Results A follow-up angiogram on days 0, 3, 7, and 14 revealed the presence of wedge-shaped poorly-enhanced areas in the parenchymal phase as seen in all groups. The size of these areas tended to increase with the particle diameter, and persisted up to day 14. On days 3, 7, and 14, parenchymal infarctions were observed histologically in all cases, and this observation corresponded with the parenchyma being supplied by the embolized arteries. GMSs of group 1 mainly reached the interlobular arteries, while those of group 3 mainly reached the interlobar arteries. In all but two cases, the GMSs were identified histologically even on day 14, and sequential degradation was histologically identified in all GMS groups. Conclusion GMSs can be used as degradable embolic materials which can control the level of embolization.

Measurement of Focal Ground-glass Opacity Diameters on CT Images: Interobserver Agreement in Regard to Identifying Increases in the Size of Ground-Glass Opacities

PURPOSE To evaluate interobserver agreement in regard to measurements of focal ground-glass opacities (GGO) diameters on computed tomography (CT) images to identify increases in the size of GGOs. MATERIALS AND METHODS Approval by the institutional review board and informed consent by the patients were obtained. Ten GGOs (mean size, 10.4 mm; range, 6.5-15 mm), one each in 10 patients (mean age, 65.9 years; range, 58-78 years), were used to make the diameter measurements. Eleven radiologists independently measured the diameters of the GGOs on a total of 40 thin-section CT images (the first [n = 10], the second [n = 10], and the third [n = 10] follow-up CT examinations and remeasurement of the first [n = 10] follow-up CT examinations) without comparing time-lapse CT images. Interobserver agreement was assessed by means of Bland-Altman plots. RESULTS The smallest range of the 95% limits of interobserver agreement between the members of the 55 pairs of the 11 radiologists in regard to maximal diameter was -1.14 to 1.72 mm, and the largest range was -7.7 to 1.7 mm. The mean value of the lower limit of the 95% limits of agreement was -3.1 ± 1.4 mm, and the mean value of their upper limit was 2.5 ± 1.1 mm. CONCLUSION When measurements are made by any two radiologists, an increase in the length of the maximal diameter of more than 1.72 mm would be necessary in order to be able to state that the maximal diameter of a particular GGO had actually increased.

Natural History of Pulmonary Subsolid Nodules: A Prospective Multicenter Study

Introduction: The purpose of this study was to evaluate the natural course of the progression of pulmonary subsolid nodules (SSNs). Materials and Methods: Eight facilities participated in this study. A total of 795 patients with 1229 SSNs were assessed for the frequency of invasive adenocarcinomas. SSNs were classified into three categories: pure ground‐glass nodules (PGGNs), heterogeneous GGNs (HGGNs) (solid component detected only in lung windows), and part‐solid nodules. Results: The mean prospective follow‐up period was 4.3 ± 2.5 years. SSNs were classified at baseline as follows: 1046 PGGNs, 81 HGGNs, and 102 part‐solid nodules. Among the 1046 PGGNs, 13 (1.2%) developed into HGGNs and 56 (5.4%) developed into part‐solid nodules. Among the 81 HGGNs, 16 (19.8%) developed into part‐solid nodules. Thus, the SSNs at the final follow‐up were classified as follows: 977 PGGNs, 78 HGGNs, and 174 part‐solid nodules. Of the 977 PGGNs, 35 were resected (nine minimally invasive adenocarcinomas [MIAs], 21 adenocarcinomas in situ [AIS], and five atypical adenomatous hyperplasias). Of the 78 HGGNs, seven were resected (five MIAs and two AIS). Of the 174 part‐solid nodules, 49 were resected (12 invasive adenocarcinomas, 26 MIAs, 10 AIS, and one adenomatous hyperplasia). For the PGGNs, the mean period until their development into part‐solid nodules was 3.8 ± 2.0 years, whereas the mean period for the HGGNs was 2.1 ± 2.3 years (p = 0.0004). Conclusion: This study revealed the frequencies and periods of development from PGGNs and HGGNs into part‐solid nodules. Invasive adenocarcinomas were diagnosed only among the part‐solid nodules, corresponding to 1% of all 1229 SSNs.