Intra-reader reliability of FDG PET volumetric tumor parameters: effects of primary tumor size and segmentation methods.

OBJECTIVE: To establish the effects of size and segmentation methods on intra-reader reliability of primary tumor metabolic tumor volume (MTV) and total glycolytic activity (TGA) in human solid tumors. METHODS: This is a retrospective study of 121 patients who had a baseline FDG PET/CT scan for oncologic staging. Volumetric parameter readings were performed in random order on two separate occasions, 12 weeks apart, by the same reader. The MTV and TGA were segmented using gradient and fixed maximum standardized uptake value (SUVmax) threshold methods. Intra-reader reliability was established by the intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS: The biases for MTV were 2.95, 14.76 and 11.13% for gradient segmentation, 38 and 50% SUVmax fixed threshold segmentations, respectively (p < 0.0001). For TGA, the corresponding biases were 0.76, 10.36 and 7.46% (p < 0.0001). There were no statistically significant differences in the biases between the first and second reads for MTV segmented for small and large volume tumors by the gradient method (p < 0.34) or 50% SUVmax threshold segmentation (p < 0.08). However, there were statistically significant differences in the corresponding biases for the 38% SUVmax threshold segmentation (p < 0.04). There were no statistically significant differences in the biases between the first and second reads for TGA segmented for small and large volume tumors (p < 0.98). CONCLUSION: Intra-reader reliability for primary tumor FDG MTV and TGA is affected by the tumor size and segmentation methods. The segmentation bias was smaller for gradient method than percentage fixed threshold method for MTV. The segmentation biases were smaller for TGA than MTV.

A proposed methodology to select radioisotopes for use in radionuclide therapy.

The American Journal of Neuroradiology has played a seminal role in the history of vertebral augmentation (VA). Because VA is increasingly being included in the multidisciplinary management of malignant vertebral compression fractures (VCFs), combined therapeutic approaches that include strategies to treat metastatic disease along with the fracture have become appealing options for patients. To that end, we recently investigated the dosimetric feasibility of treating malignant VCFs with radionuclide therapy. The goal would be to provide local control of the systemic disease beyond the pain relief and structural support provided by polymethylmethacrylate cement. The purpose of this article is to propose a methodology for evaluating radionuclides for use in radiation therapy that takes into account a number of factors including radiation characteristics, biochemical effects, production capacity, and safety. The goal of such a methodology is to introduce a systematic approach to selecting radionuclides in designing treatment regimens and future investigations and also to stimulate discussion and experimentation involving new radionuclides that may provide more effective treatments than the current isotopes in widespread use.

CT guided percutaneous calcaneoplasty: a case of metastatic intra-articular calcaneus fracture.

Symptomatic bone metastases to the calcaneus are rare.1 Minimally invasive percutaneous augmentation is an option in the palliative management of patients with metastatic bone disease, and has been commonly used in the setting of vertebral compression fractures.2 Calcaneal augmentation can potentially allow for earlier weight bearing and a shorter period of disability. A case report is presented of percutaneous intra-articular calcaneal fracture augmentation using polymethyl methacrylate.

Cerebral concussion in the monkey: an experimental model.

A statistically significant experimental model has been developed for reproducing head injury by impact in the monkey. Results with 80 monkeys subjected to occipital impact under specified conditions ( duration of phenomena, 1 to 10 milliseconds) enable the construction of curves relating the production of experimental cerebral concussion in 10, 50, and 90 percent of the monkeys to the average impulse of the blow in pounds-seconds, as well as to the average linear acceleration of the head. These curves are proposed as a baseline from which blows to various parts of the head, as well as nonimpacting impulsive loads, can be studied under various conditions of protection and according to varioucs time regimes.