Method of duplicating film using the CR system: evaluation of detectability in a simulated nodule.

PURPOSE: Since film processors used for screen-film systems have been decreasing recently, it is becoming difficult to develop duplicating film (Dup film) used conventionally. The purpose of this study was to evaluate the usefulness of the method of duplicating film using a computed radiography (CR) system. MATERIALS AND METHODS: The process of duplicating film using CR is 1) to eliminate energy accumulated on the imaging plate (IP) using white light, 2) to accumulate energy on the whole surface, and 3) to place the original film in piles. 4) After an exposure of white light, duplicated films can be obtained by CR system. In order to evaluate the reproducibiliy of our system, duplicated films were read by experienced observers and receiver operating characteristic (ROC) analysis was carried out. Observers read 50 images with a simulated nodule and 50 images without a simulated nodule. RESULTS: The average Az values were 0.94 for the original films, 0.91 for films duplicated using Dup film, and 0.90 for films duplicated using the CR system. When the two-tailed paired-T test was performed for each result, there were no statistically significant differences at p<0.05. CONCLUSION: The detectability of a simulated nodule for films duplicated using the CR system did not differ from the detectability of films duplicated using Dup film. This method may be a reasonable substitute for the conventional duplication system.

[Study of multiple cerebral aneurysms comprised of both ruptured and unruptured aneurysm--an analysis of incidence rate with respect to site and size].

The purpose of this investigation was to study the incidence rate of rupture with respect to the site and size of multiple cerebral aneurysms that include both ruptured and unruptured aneurysms. Site and size were investigated in 58 cases of this type of multiple cerebral aneurysm. All cerebral aneurysms were examined with MR angiography, 3D-CT angiography and digital subtraction angiography, as well as seeing measured using 3D-CT or digital subtraction angiography. As regards the site of the 58 ruptured cerebral aneurysms under study, 18 were internal carotid aneurysms (C2 or C3: 4 cases, IC-PC: 12 cases, IC-ancho.: 1 case, IC terminal: 1 case), 25 were anterior communicating aneurysms, 10 were middle cerebral aneurysms, 4 were anterior cerebral aneurysms and 1 case was a VA-PICA aneurysm. The ruptured internal carotid aneurysms were 4.0-21.0 mm in size, the anterior communicating aneurysms were 1.8-13 mm, the middle cerebral aneurysms were 2.0-21.3 mm, the anterior cerebral aneurysms were 3.2-9.1 mm, and the VA-PICA aneurysm was 4.4 mm. The sites of the 89 unruptured cerebral aneurysms break down as follows: 29 were internal carotid aneurysms (C2 or C3: 4 cases, IC-PC: 10 cases, IC-ancho.: 10 cases, IC terminal: 5 cases), 18 were anterior communicating aneurysms, 34 were middle cerebral aneurysms, and there were 5 cases of posterior circulation aneurysm. In size, the unruptured internal carotid aneurysms were 1.0-18.3 mm, the anterior communicating aneurysms were 1.0-6.5 mm, the middle cerebral aneurysms were 1.0-10.3 mm, the anterior cerebral aneurysms were 1.0-3.3 mm, and the posterior circulation aneurysms were 2.2-17.3 mm. Out of 58 ruptured cerebral aneurysms, 44 were of the largest size category, and 53 (91.4%) were in the largest size category and/or anterior communicating aneurysms. The accumulated incidence rate of rupture of anterior communicating aneurysms rose suddenly upon reaching 2 mm in size, and after reaching 3 mm, these aneurysms accounted for a nearly uniform 55%-60% of the incidence rate of rupture. The accumulated incidence rate of rupture of IC-PC aneurysms rose drastically at 4 mm in size with the data describing a parabolic slope when graphed. IC-PC aneurysms represented a uniform 55% of the incidence rate of rupture after reaching 8 mm in size. The accumulated incidence rate of rupture of middle cerebral aneurysms rose in a gently sloping parabola beginning at 4 mm, and stabilized at 20% upon reaching 10 mm. These results suggest that each site is associated with a characteristic size and rate of aneurismal rupture. Special attention should thus be paid to large and anterior communicating aneurysms when operating on multiple cerebral aneurysms.