Tatsuya Gomi

A two-step ligand exchange reaction generates highly water-dispersed magnetic nanoparticles for biomedical applications

The high-temperature thermolysis of fatty acid–iron complexes generates magnetic nanoparticles (MNPs) of a precisely controlled size coated with fatty acids and dispersed in oil. Because they are water-immiscible, MNPs are unsuitable for water-based biomedical applications. Ligand exchange reactions that transform oil- into water-dispersed MNPs have attracted considerable attention, but are difficult to perform. In this paper, we report the successful preparation of size-controlled and highly water-dispersed MNPs, which have 4, 8 and 20 nm diameter by a unique two-step ligand exchange reaction. As temporary ligands, we selected thiomalic acid (TMA), which possesses moderate affinity toward MNPs and is soluble in both oil and water to remove fatty acids by XANES analyses. Next we selected the citric acids as secondary ligands for TMA-exchanged MNPs to be highly dispersed in water to remove TMA from the surface of MNPs. And the resulting highly water-dispersed MNPs are expected to be available as MRI contrast agents and hyperthermia carriers.

Evaluation of the acute adverse reaction of contrast medium with high and moderate iodine concentration in patients undergoing computed tomography

PurposeThe aim of this prospective study was to evaluate and compare acute adverse reactions between contrast medium containing moderate and high concentrations of iodine in patients undergoing computed tomography (CT).Materials and methodsA total of 945 patients undergoing enhanced CT were randomly assigned to receive one of two doses of contrast medium. We then prospectively investigated the incidence of adverse reactions. Iopamidol was used as the contrast medium, with a high concentration of 370 mg I/ml and a moderate concentration of 300 mg I/ml. The frequency of adverse reactions, such as pain at the injection site and heat sensation, were determined.ResultsAcute adverse reactions were observed in 2.4% (11/458) of the moderate-concentration group compared to 3.11% (15/482) of the high-concentration group; there was no significant difference in incidence between the two groups. Most adverse reactions were mild, and there was no significant difference in severity. One patient in the high-concentration group was seen to have a moderate adverse reaction. No correlation existed between the incidence of adverse reactions and patient characteristics such as sex, age, weight, flow amount, and flow rate. The incidence of pain was not significantly different between the two groups. In contrast, the incidence of heat sensation was significantly higher in the high-concentration group.ConclusionsThe incidence and severity of acute adverse reactions were not significantly different between the two groups, and there were no severe adverse reactions in either group.

Primary cardiac synovial sarcoma: a case report and literature review.

Primary cardiac synovial sarcoma is a rare disease. A 51‐year‐old man visited our hospital with the chief complaint of palpitations and shortness of breath while exercising. Copious bloody pericardial effusion and a multicystic intrapericardial tumor were detected. A primary cardiac malignant tumor was suspected, an open‐chest tumor resection was performed with the objectives of diagnosis and treatment. Histologically, the tumor cells were uniformly spindle‐shaped with an ovoid or oval nucleus, they had proliferated in fascicular fashion. In addition myxoid degeneration, a hemangiopericytomatous vascular pattern and pseudorosette formation were seen in some areas of the tumor. Based on the histopathological and immunohistochemical findings and reverse transcription polymerase chain reaction detection of SS18‐SSX1 fusion transcripts, a monophasic fibrous type synovial sarcoma was diagnosed. Postoperative radiation therapy was administered and there had been no recurrence 9 months after the surgery.

Wandering spleen with gastric volvulus and intestinal non-rotation in an adult male patient

We report an extremely rare case of wandering spleen (WS) complicated with gastric volvulus and intestinal non-rotation in a male adult. A 22-year-old man who had been previously treated for Wilson disease was admitted with severe abdominal pain. Radiological findings showed WS in the midline of the pelvic area. The stomach was mesenteroaxially twisted and intestinal non-rotation was observed. Radiology results did not show any evidence of splenic or gastrointestinal (GI) infarction. Elective emergency laparoscopy confirmed WS and intestinal non-rotation; however, gastric volvulus was not observed. It was suspected that the stomach had untwisted when gastric and laparoscopic tubes were inserted. Surgery is strongly recommended for WS because of the high risk of serious complications; however, some asymptomatic adult patients are still treated conservatively, such as the patient in this study. The present case is reported with reference to the literature.

Acute appendicitis following endoscopic mucosal resection of cecal adenoma

Endoscopic mucosal resection (EMR) allows the removal of flat or sessile lesions, laterally spreading tumors, and carcinoma of the colon or the rectum limited to the mucosa or the superficial submucosa. Acute appendicitis is the most common abdominal emergency requiring emergency surgery, and it is also a rare complication of diagnostic colonoscopy and therapeutic endoscopy, including EMR. In the case presented here, a 53-year-old female underwent colonoscopy due to a positive fecal occult blood test and was diagnosed with cecal adenoma. She was referred to our hospital and admitted for treatment. The patient had no other symptoms. EMR was performed, and 7 h after the surgery, the patient experienced right -lower abdominal pain. Laboratory tests performed the following day revealed a WBC count of 16000/mm(3), a neutrophil count of 14144/mm(3), and a C-reactive protein level of 2.20 mg/dL, indicating an inflammatory response. Computed tomography also revealed appendiceal wall thickening and swelling, so acute appendicitis following EMR was diagnosed. Antibiotics were initiated leading to total resolution of the symptoms, and the patient was discharged on the sixth post-operative day. Pathological analysis revealed a high-grade cecal tubular adenoma. Such acute appendicitis following EMR is extremely rare, and EMR of the cecum may be a rare cause of acute appendicitis.

Radial MRI during free breathing in contrast-enhanced hepatobiliary phase imaging

Background Use of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for diagnosis of hepatic tumors has been previously reported. Fat-saturated 3D T1-weighted gradient echo sequence (TIGRE) imaging using a breath-hold technique is usually used for dynamic studies and hepatobiliary phase Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). In cases where the patient has difficulty holding their breath, this scanning method can be difficult. Purpose To investigate the usefulness of a fat-saturated T1-weighted spin-echo (SE) sequence using a radial read-out (radial acquisition regime-SE, RADAR-SE) during free breathing for hepatobiliary phase Gd-EOB-DTPA-enhanced MRI. Material and Methods Images were acquired at 1.5 T. First, a phantom with diluted Gd-EOB-DTPA was scanned using the TIGRE sequence and the RADAR-SE sequence. Contrast ratios of the sequences were compared. Next, the hepatobiliary phase was imaged in 62 patients using the TIGRE sequence with breath-hold and the RADAR-SE during free breathing. Qualitative and quantitative evaluations were compared. Results In the phantom study, RADAR-SE had a higher contrast ratio than TIGRE. In the clinical study, artifacts were more conspicuous in RADAR-SE compared to TIGRE images in the qualitative evaluation. However, RADAR-SE images were equal to or better than TIGRE images in patients who had difficulty holding their breath. The signal intensity ratio of the liver was statistically higher using RADAR-SE than TIGRE. Conclusion RADAR-SE can be useful for hepatobiliary phase Gd-EOB-DTPA-enhanced MRI in patients who have difficulty holding their breath.

Development of diffusion-weighted image using a 0.3T open MRI.

The purpose of this study was to develop a new technique for diffusion-weighted MRI (DWI) with a low-field scanner. DWI is becoming important for assessment of acute stroke. Until recently DWI required expensive technology. We developed multishot-DWI sequence for 0.3T open type MR imager. We prospectively studied forty patients on this 0.3T MRI and compared this DWI to single-shot-DWI by 1.5T-MRI. Group A: Twenty-four patients with acute cerebral infarctions detected by 1.5T-DWI were re-examined using 0.3T-DWI within 24 hours. Sixteen patients with acute cerebral infarctions detected by 0.3T-DWI were re-examined using 1.5T-DWI within 24 hours. In 22 (92%) of 24 cases, 0.3T-DWI showed high signal. In the other two patients, motion artifact distorted 0.3T-DWI. Group B: In all 16 patients, all infarctions detected by 0.3T-DWI showed high signal on 1.5T-DWI. These preliminary data show that, as long as the patient is able to keep still, multishot-DWI can be acquired successfully on a 0.3T open type MRI system.

Factors associated with delayed gastric emptying in patients with stent placement for malignant gastric outlet obstruction

Background and study aims: Delayed gastric emptying (DGE) is an important factor in determining the clinical outcome in patients with stent placement for malignant gastric outlet obstruction but the factors associated with DGE remain unclear. The aim of this study was to investigate whether clinicopathologic data could be used to identify the factors for DGE in such patients. Patients and methods: A prospective, single-arm, observational clinical study was performed in a referral hospital in Japan. A total of 54 patients with stent placement for malignant gastric outlet obstruction were enrolled. A gastric emptying scintigraphy test was performed 1 week after stent placement. The relationship between DGE and clinicopathologic factors was investigated, and also the relationship between DGE and stent patency time, eating period (when the patient was able to maintain oral intake), and survival time. Results: A total of 38.9 % (21 /54) of patients had DGE. The following were identified as independent predictive factors of DGE: opioid use (odds ratio, 5.32; 95 % confidence interval [95 %CI], 1.07 – 26.41; p = 0.04), chemotherapy before stent placement (odds ratio, 8.03; 95 %CI, 1.85 – 34.95; p = 0.006), and smaller stent diameter (odds ratio, 13.59; 95 %CI, 1.72 – 107.41; p = 0.01). No relationship was found between DGE and the level of oral intake, stent patency time, eating period, and survival time. Conclusions: The factors associated with DGE after stent placement include those associated with the patient’s tumor as well as factors relating to their treatment, including stenting. The clinical and functional results after stent placement appear to be unrelated to the gastric emptying findings.

Revisit image control for pediatric chest radiography

PurposeThe aim of this study was to analyze the fraction defectiveness and efficacy of the patient immobilization device (PID) for pediatric chest radiography.Materials and methodsWe examined 840 plain chest radiographs in six hospitals, including four childrens hospitals and two general hospitals. The mean age of the patients was 1.9 years (range 0–5 years). Two board-qualified pediatric radiologists rated (into three grades, by consensus) the degree of inspiration, rotation, lordosis, scoliosis, and cutoff or coning as well as the quality of the chest radiographs.ResultsThe incidence of “poor” and “very poor” quality examinations was 2/140 and 3/140 in each of two childrens hospitals using PID. The corresponding figures were 9/139 and 17/140 in the two childrens hospitals that did not use PID. The general hospital using PID had 14/140 “poor” and “very poor” examinations. The general hospital that did not use PID had 28/140 “poor” and “very poor” examinations. Thus, statistically better quality chest radiography was obtained with the use of PID (P < 0.001). Likewise, rotation, lordosis, and scoliosis were less frequently diagnosed as present when PID was used (P < 0.001, 0.001, 0.05). Cutoff or coning had no relation to the use of PID (P = 0.13). No significant difference was found between the degree of inspiration and the use of PID (P = 0.56).ConclusionFraction defectiveness in the general hospital that did not use PID was as much as 14 times higher than that of the childrens hospitals that used PID. The patient immobilization device is recommended for hospitals with technologists not specifically trained for pediatric examination.

Evaluation of the changes in signals from the spleen using ferucarbotran

PurposeBecause superparamagnetic iron oxide is actively taken into the reticuloendothelial system, the signal intensity observed on T2-weighted images is reduced not only in the liver but also in the spleen. There is no difference in the reduction in signal intensity in the liver after contrast between the ferumoxides and ferucarbotran, but the reduction in signal intensity in the spleen is considerable. In the present study, we examined the efficacy of T2*-weighted imaging to compensate for the reduction in signal intensity in the spleen by administering ferucarbotran.Materials and methodsWe examined the images obtained from 35 patients who underwent MRI with ferucarbotran. T2-weighted images and T2*-weighted images were obtained before and after administration of ferucarbotran, and the changes in signal intensity in the liver and spleen were then analyzed.ResultsA reduction in signal intensity was observed in the liver by both T2- and T2*-weighted imaging. In the spleen, the signal intensity was reduced on T2-weighted images but was not reduced on T2*-weighted images.ConclusionThe reduction in signal intensity due to administration of ferucarbotran is low in the spleen. Thus, it was considered necessary to approach the problem of diagnosing ectopic splenic tissue using ferucarbotran with caution.