Imaging of mandible invasion by oral squamous cell carcinoma using computed tomography, cone-beam computed tomography and bone scintigraphy with SPECT.

OBJECTIVES: The objective of this paper is to evaluate the predictability of preoperative tumour bone invasion of the mandible by squamous cell carcinoma of the oral cavity using CT, cone-beam CT and bone scintigraphy with SPECT. MATERIAL AND METHODS: Eighty-four patients who had received CT, SPECT or cone-beam computed tomography (CBCT), as well as a further 48 patients who undergone all these investigations for preoperative evaluation of bone invasion were included in the study. A case-control analysis and the receiver operating characteristics were performed. Histological results of bone specimens served as the gold standard for assessment of bone invasion. RESULTS: CBCT and SPECT showed a comparable sensitivity for bone invasion (93 % [CI 0.816-0.972] and 96 % [CI 0.867-0.990], respectively) which was significantly higher than that of CT (63 % [CI 0.488-0.752]). Further, CBCT obtained higher specificity than SPECT (62 % [CI 0.478-0.743] and 48 % [CI 0.342-0.614], respectively), whereas CT showed the best specificity among the investigation methods (81 % [CI 0.677-0.896]). CONCLUSIONS: CT scan provides by its high specificity and positive predictive value a precise imaging technique for clinical routine. However, CBCT shows a much higher sensitivity for cortical bone invasion and a better negative predictive value. With a significantly lower exposure dose it can rule out this invasion effectively and prevent overtreatment. CLINICAL RELEVANCE: Considering the high-resolution images delivered by CBCT along with minimized artefacts in the mandible it provides an alternative imaging technique, which could be combined and accomplished with another soft-tissue imaging modality like MRI to obtain optimal hard and soft-tissue visualisation in patients with squamous cell carcinoma of the oral cavity.

Faster nerve regeneration after sciatic nerve injury in mice over-expressing basic fibroblast growth factor.

Basic fibroblast growth factor (FGF-2) is expressed in the peripheral nervous system and is up-regulated after nerve lesion. It has been demonstrated that administration of FGF-2 protects neurons from injury-induced cell death and promotes axonal regrowth. Using transgenic mice over-expressing FGF-2 (TgFGF-2), we addressed the importance of endogenously generated FGF-2 on sensory neuron loss and sciatic nerve regeneration. After sciatic nerve transection, wild-type and transgenic mice showed the same degree of cell death in L5 spinal ganglia. Also, the number of chromatolytic, eccentric, and pyknotic sensory neurons was not changed under elevated levels of FGF-2. Morphometric evaluation of intact nerves from TgFGF-2 mice revealed no difference in number and size of myelinated fibers compared to wild-type mice. One week after crush injury, the number of regenerated axons was doubled and the myelin thickness was significantly smaller in transgenic mice. After 2 and 4 weeks, morphometric analysis and functional tests revealed no differences in recovery of sensory and motor nerve fibers. To study the role of FGF-2 over-expression on Schwann cell proliferation during the early regeneration process, we used BrdU-labeling to mark dividing cells. In transgenic mice, the number of proliferating cells was significantly increased distal to the crush site compared to wild-types. We propose that endogenously synthesized FGF-2 influences early peripheral nerve regeneration by regulating Schwann cell proliferation, axonal regrowth, and remyelination.