Medical whole-body positron emission tomography (PET), one of the most successful molecular imaging technologies, has been widely used in the fields of cancer diagnosis, cardiovascular disease diagnosis and cranial nerve study. But, on the other hand, the sensitivity, spatial resolution and signal-noise-ratio of the commercial medical whole-body PET systems still have some shortcomings and a great room for improvement. The sensitivity, spatial resolution and signal-noise-ratio of PET system are largely affected by the performances of the scintillators and the photo detectors. The design of a PET system is usually a trade-off in cost and performance. A better image quality can be achieved by optimizing and balancing the key components which affect the system performance the most without dramatically increases in cost. With the development of the scintillator, photo-detector and high speed electronic system, the performance of medical whole-body PET system would be dramatically improved. In this paper, we report current progresses and discuss future directions of the developments of technologies in medical whole-body PET system.
ObjectiveTo investigate the clinical outcome of Ponte osteotomy for old osteoporotic multi-segment vertebral fracture combined with thoracolumbar kyphosis in elderly. MethodsBetween April 2007 and December 2012, 11 elderly patients with thoracolumbar kyphosis caused by old osteoporotic multi-segment vertebral fracture received Ponte osteotomy. There were 4 males and 7 females, with an average age of 69 years (range, 62-76 years) and with an average disease duration of 4 years (range, 10 months to 7 years). A total of 51 vertebrae was involved in fracture, including T5 in 1, T8 in 1, T9 in 1, T10 in 5, T11 in 8, T12 in 11, L1 in 11, L2 in 10, and L3 in 3. Based on Frankel classification, there were 9 cases of grade E and 2 cases of grade D. The Cobb angle of thoracolumbar kyphosis and the distance of sagital plane between C7 plump line and the posterior superior corner of S1 (sagittal vertical axis distance, SVA) were measured at pre-operation, at 2 weeks after operation, and last follow-up. The effectiveness of the treatment was appraised by visual analogue scale (VAS). ResultsAll the operations were successfully completed. Cerebrospinal fluid leakage occurred in 3 cases, and was cured after symptomatic treatment. Eleven patients were followed up 22 months on average (range, 7-38 months). Back pain symptoms, the appearance, and the trunk balance were significantly improved after operation. Postoperatively neurological symptoms were not aggravated. In 2 cases of grade D, 1 case recovered to grade E, and 1 case had no improvement. Osseous fusion was observed at 6.7 months on average (range, 5-9 months) in 10 patients except 1 patient who had no complete fusion at 7 months after operation. There was no infection, failure of internal fixation, or other complications. At 2 weeks after operation and last follow-up, the VAS score, Cobb angle, and SVA were significantly improved when compared with preoperative ones (P<0.05), but no significant difference was found between at 2 weeks and last follow-up (P>0.05). The correction rate of Cobb angle was 70.6%±2.2% at 2 weeks after operation and was 66.7%±1.3% at last follow-up, showing no significant difference (t=25.20, P=0.13). ConclusionPonte osteotomy is effective for old osteoporotic multi-segment vertebral fracture combined with thoracolumbar kyphosis in elderly. It can obtain satisfactory sagittal balance.