A questionnaire about radiation safety management of the draining-water system at nuclear medicine facilities

We conducted a questionnaire survey about radiation-safety management condition in Japanese nuclear medicine facilities to make materials of proposition for more reasonable management of medical radioactive waste. We distributed a questionnaire to institutions equipped with Nuclear Medicine facilities. Of 1,125 institutions, 642 institutes (52.8%) returned effective answers. The questionnaire covered the following areas: 1) scale of an institution, 2) presence of enforcement of radiotherapy, 3) system of a tank, 4) size and number of each tank, 5) a form of draining-water system, 6) a displacement in a radioactive rays management area, 7) a measurement method of the concentration of medical radioactive waste in draining water system, 8) planned and used quantity of radioisotopes for medical examination and treatment, 9) an average displacement of hospital for one month. In most institutions, a ratio of dose limitation of radioisotope in draining-water system was less than 1.0, defined as an upper limitation in ordinance. In 499 hospitals without facilities of hospitalization for unsealed radioisotope therapy, 473 hospitals reported that sum of ratios of dose limits in a draining-water system was less than 1.0. It was calculated by used dose of radioisotope and monthly displacement from hospital, on the premise that all used radioisotope entered in the general draining-water system. When a drainage including radioactivity from a controlled area join with that from other area before it flows out of a institution, it may be diluted and its radioactive concentration should be less than its upper limitation defined in the rule. Especially, in all institutions with a monthly displacement of more than 25,000 m3, the sum of ratio of the concentration of each radionuclide to the concentration limit dose calculated by used dose of radioisotope, indicated less than 1.0.     

Computer-aided detection in computed tomography colonography: current status and problems with detection of early colorectal cancer

PURPOSE: The aim of this study was to evaluate the usefulness of computer-aided detection (CAD) in diagnosing early colorectal cancer using computed tomography colonography (CTC). MATERIALS AND METHODS: A total of 30 CTC data sets for 30 early colorectal cancers in 30 patients were retrospectively reviewed by three radiologists. After primary evaluation, a second reading was performed using CAD findings. The readers evaluated each colorectal segment for the presence or absence of colorectal cancer using five confidence rating levels. To compare the assessment results, the sensitivity and specificity with and without CAD were calculated on the basis of the confidence rating, and differences in these variables were analyzed by receiver operating characteristic (ROC) analysis. RESULTS: The average sensitivities for the detection without and with CAD for the three readers were 81.6% and 75.6%, respectively. Among the three readers, only one reader improved sensitivity with CAD compared to that without. CAD decreased specificity in all three readers. CAD detected 100% of protruding lesions but only 69.2% of flat lesions. On ROC analysis, the diagnostic performance of all three readers was decreased by use of CAD. CONCLUSION: Currently available CAD with CTC does not improve diagnostic performance for detecting early colorectal cancer. An improved CAD algorithm is required for detecting flat lesions and reducing the false-positive rate.     

Decreased peroxynitrite inhibitory activity in induced sputum in patients with bronchial asthma

BACKGROUND: The production of peroxynitrite, an extremely potent oxidant, is increased in inflammatory lung disease. It is therefore important to measure antioxidant activity against peroxynitrite in epithelial lining fluid to examine the physiological effects of peroxynitrite in the airways of patients with asthma. This study was designed to determine whether peroxynitrite inhibitory activity in induced sputum is correlated with clinical characteristics and airway inflammatory indices in asthmatic patients. METHODS: Inflammatory indices were measured in induced sputum from 25 patients with asthma and 12 normal control subjects. Peroxynitrite inhibitory activity was also measured by monitoring rhodamine formation in sputum samples. RESULTS: Peroxynitrite inhibitory activity in induced sputum was significantly lower in asthmatic patients (52.4 (24.5)%) than in normal control subjects (92.1 (3.9)%, p<0.0001). Its activity was significantly correlated with forced expiratory volume in 1 second (FEV(1)) % predicted (r=0.774, p<0.0001) and bronchial hyperreactivity to methacholine (r=0.464, p=0.023). There was a significant negative correlation between peroxynitrite inhibitory activity and the degree of eosinophilic airway inflammation (% eosinophils, r=-0.758, p<0.0001; eosinophil cationic protein, r=-0.780, p<0.0001). CONCLUSIONS: Decreased peroxynitrite inhibitory activity occurs in induced sputum of asthmatic patients. Since even in patients with stable asthma the airway lining fluid lacks peroxynitrite inhibitory activity, large amounts of peroxynitrite, which are further increased during an acute asthma attack, would not be completely inactivated and asthmatic airways might have markedly increased susceptibility to peroxynitrite induced airway injury.     

Retroperitoneal bronchogenic cyst: a case report

A rare case of retroperitoneal bronchogenic cyst is presented. A 50-year-old man was referred to our hospital for an investigation of a retroperitoneal mass. Computed tomography and magnetic resonance imaging confirmed a retroperitoneal mass, about 4 cm in diameter, adjacent to the left kidney and spleen. On the basis of these imaging modalities, a definitive diagnosis of this mass could not be made. So, resection of the mass was performed. The removed mass was an unilocular cyst and filled with mucinous fluid. Histopathologically, the cyst wall was composed of a fibrovascular connective tissue containing mucus-secreting glands and cartilages and was lined by ciliated pseudostratified columnar epitherium. Thus, a diagnosis of bronchogenic cyst was made. Bronchogenic cysts are rare congenital anomalies of the primitive foregut and usually develop in the mediastinum and lung.     

Prevention of Acute Lung Allograft Rejection in Rat by CTLA4Ig

CTLA4 immunoglobulin (CTLA4Ig), which binds with a high affinity to B7-1 and B7-2, interrupts T-cell activation by inhibiting costimulatory signal. CTLA4Ig has been used in hopes of achieving antigen-specific tolerance induction in several solid organ transplants. In lung allograft rejection, however, its use has been controversial in terms of its effect on prevention of rejection. In the present study, the effect of murine CTLA4Ig on rat-lung allograft rejection was investigated. Rat left-lung transplantation was performed in an RT1 incompatible donor (Brown Norway; BN)-recipient (F344) combination. All allografts (n = 12) without any treatment were rejected within 7 days after transplantation. A single injection of murine form CTLA41g at a dose of 100 microg intraperitoneally (ip) or intravenously (iv) on day 1 post-transplantation achieved long-term graft survival (>90days) in 2/5 (40%) and 3/8 (38%), respectively. Moreover, 6/7 (86%) allografts in rats that received iv injection of 500 microg CTLA4Ig survived more than 90days. Allograft survival in the CTLA4Ig 500 microg iv recipient group was significantly longer than that in the no-treatment control or control immunoglobulin group (p <0.01). Four out of seven recipients bearing functional allografts for more than 90 days with the CTLA4Ig treatment accepted donor-specific skin grafts, whereas all third-party skin grafts (n=3) were rejected. Prevention of rat-lung allograft rejection could be achieved by intravenous administration of CTLA4Ig, resulting in long-term allograft survival with acceptance of donor-specific skin grafts.     

Rupture of previously documented asymptomatic unruptured aneurysms--aneurysm size: risk factor for aneurysm rupture

The natural history of asymptomatic unruptured aneurysms is not clear. We conducted a follow up study of 100 patients (since 1993) with 122 asymptomatic unruptured aneurysms that had not been operated on. We report five patients with previously documented asymptomatic unruptured aneurysms smaller than 10 mm in diameter that subsequently ruptured. Among the 100 patients, five had suffered subarachnoid hemorrhage (SAH) due to rupturing of an aneurysm. Of the 5 cases, 1 was male and 4 were female, with ages ranging from 59-73 years (mean age, 68 years). The aneurysms were on the MCA in 3, on the BA-SCA in 1, on the IC-PC in 1. The maximal diameter of the aneurysms at diagnosis ranged from 4.5 to 8 mm. The period from discovery to SAH was from 4 to 69 months and the cumulative rate of rupture of the aneurysms was 1.5 percent per year. Four of the 5 cases increased in size after the rupture. In our series, 2 of the 5 cases showed enlargement and the development of an aneurysmal bleb in the follow up MRA and 3D-CTA. The present study demonstrates that five asymptomatic unruptured aneurysms less than 10 mm in diameter subsequently ruptured. We ought to seriously consider the assertion published in the New England Journal of Medicine (Dec. 10, 1998), that unruptured aneurysms less than 10 mm in diameter have a very low probability of subsequent rupture.     

Development of port-site metastasis after pneumoperitoneum

Background: Port-site metastasis is a critical problem in laparoscopic cancer surgery; the pathogenesis and means of prevention are still unclear. The aim of this study was to clarify by scanning electron microscopy the initial morphologic changes in the development of port-site metastasis. Methods: Fifteen nude mice were injected with human gastric cancer (MKN 45) cells. Mice were killed on days 0, 3, and 8 (n = 5 each day) after intraperitoneal injection of 5 × 105 cancer cells and carbon dioxide (CO2) pneumoperitoneum at 4–6 mmHg for 20 min. The abdominal wall with the port sites was harvested and examined under both light and scanning electron microscopy. Results: Immediately after CO2 pneumoperitoneum (day 0), the abdominal peritoneum was peeled away and the muscular layer was destroyed at the port site in all mice. Several cancer cells were attached to the injured port sites. On day 3, the subperitoneal tissue and muscular layer defects were replaced by granulation tissue, and several cancer cells were observed in the subperitoneal tissue. On day 8, a small nodule was macroscopically visible at the port site; it was completely covered by mesothelial cells and consisted of numerous cancer cells. Conclusions: Free cancer cells appear to attach to the injured port sites immediately after CO2 pneumoperitoneum, and these are associated with the development of port-site metastasis after laparoscopic cancer surgery.     

Complete paralysis of the quadriceps muscle caused by traumatic iliacus hematoma: a case report

 A 15-year-old girl who developed traumatic iliacus hematoma and complete paralysis of the quadriceps muscle is reported. The current case and literature review revealed that incomplete quadriceps paralysis associated with traumatic iliacus hematoma is likely to progress to complete paralysis in days or weeks as a result of increased intracompartmental pressure. However, surgical decompression of the femoral nerve could produce good results even in patients who have complete quadriceps paralysis preoperatively. Received: April 9, 2002 / Accepted: June 28, 2002 Offprint requests to: K. Tamai