16-Detector multislice CT in the detection of stress fractures: a comparison with skeletal scintigraphy.

AIMS: To test the hypothesis that the improved resolution afforded by 16-detector computed tomography (CT) would translate to better stress fracture detection when compared with skeletal scintigraphy. MATERIALS AND METHODS: Thirty-three cases of suspected stress fractures in 26 patients were investigated using skeletal scintigraphy and 16-detector CT performed on the same day. Planar images of the lower limbs were taken 3h post-injection of 400MBq (99m)Tc-methylene diphosphonate ((99m)Tc-MDP). (99m)Tc-MDP uptake was quantified at suspected fracture sites. CT was performed using a 16-detector multisection machine employing 0.75mm detectors and images reconstructed in 0.5mm increments. Examinations were reported independently and discordant results were compared at follow-up. RESULTS: At initial reporting scintigraphy identified fractures in 13 of the 33 cases and CT identified four of the 33. In one case, on review of the CT images, a fracture was present in the distal fibula that was not initially identified. This resulted in eight scintigraphic-positive CT-negative discordant cases. The (99m)Tc-MDP uptake was significantly lower in the discordant fracture group compared with the concordant group (p<0.01). CONCLUSIONS: Despite technological advances in CT, scintigraphy appeared to detect more stress fractures. As such, multidetector CT should not be used as a routine initial investigation in stress fracture detection. The potential use of (99m)Tc-MDP quantification at fracture sites is of interest and may be worth further investigation.

Fast CT for aortic dissection.

Results were evaluated in 81 patients with suspected acute aortic dissection who were examined on a fast CT system capable of a 1 s data acquisition time. 17 patients had Type A and nine had Type B dissections. Radiological assessment provided 78 confident reports and expressed some uncertainty about the diagnosis in three patients. Overall sensitivity for aortic dissection was 96.2% and specificity was 96.4%. When 78 confident reports alone were considered, both sensitivity and specificity reached 100%. Reconstruction of data at 100 ms intervals allowed discrimination between artefacts in the ascending aorta and Type A dissections. CT can often be used as the single investigation prior to surgery for acute Type A dissections.