Intraoperative fluorescence perfusion assessment should be corrected by a measured subject-specific arterial input function.

SIGNIFICANCE: The effects of varying the indocyanine green injection dose, injection rate, physiologic dispersion of dye, and intravenous tubing volume propagate into the shape and magnitude of the arterial input function (AIF) during intraoperative fluorescence perfusion assessment, thereby altering the observed kinetics of the fluorescence images in vivo. AIM: Numerical simulations are used to demonstrate the effect of AIF on metrics derived from tissue concentration curves such as peak fluorescence, time-to-peak (TTP), and egress slope. APPROACH: Forward models of tissue concentration were produced by convolving simulated AIFs with the adiabatic approximation to the tissue homogeneity model using input parameters representing six different tissue examples (normal brain, glioma, normal skin, ischemic skin, normal bone, and osteonecrosis). RESULTS: The results show that AIF perturbations result in variations in estimates of total intensity of up to 80% and TTP error of up to 200%, with the errors more dominant in brain, less in skin, and less in bone. Interestingly, error in ingress slope was as high as 60% across all tissue types. These are key observable parameters used in fluorescence imaging either implicitly by viewing the image or explicitly through intensity fitting algorithms. Correcting by deconvolving the image with a measured subject-specific AIF provides an intuitive means of visualizing the data while also removing the source of variance and allowing intra- and intersubject comparisons. CONCLUSIONS: These results suggest that intraoperative fluorescence perfusion assessment should be corrected by patient-specific AIFs measured by pulse dye densitometry.

Central xanthoma of the jaw in association with Noonan syndrome.

Xanthomas are histiocytic lesions of the skin, soft tissue, and bone and are generally considered to be reactive in nature. When they arise in the bones of the jaw, they are referred to as central xanthomas. New evidence supports the hypothesis that central xanthomas are a separate and distinct entity from their extragnathic counterparts. Noonan syndrome (NS) is an autosomal dominant disorder that has been associated with giant cell lesions, which also commonly occur in the jaw. We present a case of a 15-year-old boy with NS who presented with a radiolucent lesion of the mandible that on excision was found to be a central xanthoma. Although giant cell lesions have been well described in NS, xanthomas of the jaw have not been reported. We will also discuss the entities that must be excluded before making a diagnosis of central xanthoma, as this can affect both treatment and follow-up.

Intraosseous ameloblastoma.

Ameloblastomas are benign slow-growing aggressive neoplasms with a poorly understood potential for rare metastasis. They are capable of reaching large sizes with extensive local bone erosion and destruction. They are composed of a mixture of ameloblastic epithelium and mesenchyme and arise from rests of outer and inner enamel epithelium and dental lamina. Microscopically, ameloblastomas are recognizable from their recapitulation of embryologic ameloblasts and stellate reticulum. There are 3 subtypes: the conventional or solid-multicystic variant, the unicystic variant, and the desmoplastic variant. Treatment planning for a given tumor includes consideration of location, primary versus recurrent, size, presence of cortical perforation, and age and health of the patient. Complete excision is recommended for conventional and desmoplastic variants. The unicystic variant requires additional subtyping to determine the best treatment approach.