ABSTRACT
BACKGROUND: Limited data exist about the use, efficacy, and prognostic factors influencing outcome when CyberKnife is used to treat dogs with intracranial neoplasia. OBJECTIVES: To determine the prognosis and associated prognostic factors for dogs that were imaged, determined to have primary intracranial tumors, and treated with CyberKnife radiotherapy. ANIMALS: Fifty-nine dogs treated with CyberKnife radiotherapy for primary intracranial tumors. METHODS: Retrospective medical record review of cases from January 2010 to June 2016. Data extracted from medical records included signalment, weight, seizure history, tumor location, tumor type (based on imaging), gross tumor volume, planned tumor volume, treatment dates, radiation dose, recurrence, date of death, and cause of death. RESULTS: The median progression-free interval (PFI) was 347 days (range 47 to 1529 days), and the median survival time (MST) was 738 days (range 4 to 2079 days). Tumor location was significantly associated with PFI when comparing cerebrum (median PFI 357 days; range 47-1529 days) versus cerebellum (median PFI 97 days; range 97-168 days) versus brainstem (median PFI 266 days; range 30-1484 days), P = .03. Additionally, the presumed tumor type was significantly associated with MST (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Use of Cyberknife and SRT might improve MST, compared with RT, in dogs with intracranial neoplasia.
Subject(s)
Brain Neoplasms , Dog Diseases , Radiosurgery , Animals , Brain Neoplasms/radiotherapy , Brain Neoplasms/veterinary , Dog Diseases/radiotherapy , Dog Diseases/surgery , Dogs , Neoplasm Recurrence, Local/veterinary , Radiosurgery/veterinary , Retrospective Studies , Treatment OutcomeABSTRACT
PURPOSE: A noninvasive method to monitor intratumoral Doxil delivery in individual patients during targeted tumor therapy is important to predict treatment response. The purpose of this study was to determine if a small tracer dose of technetium-99m (99mTc)-labeled liposomes could be used to quantify the effect of local hyperthermia on intratumoral Doxil extravasation. EXPERIMENTAL DESIGN: Experiments were carried out in a rat fibrosarcoma model with transplanted thigh tumors. Liposomes of approximately same size and composition as Doxil were radiolabeled using [technetium-99m (99mTc)]exametazime. Eight treatment groups received either Doxil, a tracer dose or a large dose of 99mTc-labeled liposomes, or a combination of tracer and Doxil, with or without hyperthermia. This design was chosen to assure that coadministration of both liposomal formulations did not influence their intratumoral distribution. Hyperthermia was done for 45 minutes. Scintigraphic images were obtained at 5 and 18 hours. At 18 hours, tumors were removed and gamma counts as well as doxorubicin concentrations were measured. RESULTS: Intratumoral extravasation of the 99mTc-labeled tracer could be imaged scintigraphically under normothermic and hyperthermic conditions. The thermal enhancement ratio was slightly higher for radiolabeled liposomes than for doxorubicin concentration. However, there was a significant positive correlation of intratumoral doxorubicin concentration and intratumoral uptake of the radiolabeled tracer (expressed as percentage of the injected dose per gram of tissue). Coadministration of radiolabeled liposomes did not negatively influence the amount of drug delivered with Doxil. CONCLUSIONS: The use of a radiolabeled tracer has potential value to monitor drug delivery and estimate the effect of an intervention aimed to increase liposomal accumulation, such as local hyperthermia.
Subject(s)
Doxorubicin/pharmacokinetics , Doxorubicin/therapeutic use , Fibrosarcoma/therapy , Hyperthermia, Induced/methods , Liposomes/administration & dosage , Technetium Tc 99m Exametazime/administration & dosage , Animals , Antibiotics, Antineoplastic/pharmacokinetics , Antibiotics, Antineoplastic/therapeutic use , Combined Modality Therapy/methods , Diagnostic Imaging/methods , Dose-Response Relationship, Drug , Drug Carriers/administration & dosage , Feasibility Studies , Female , Liposomes/pharmacokinetics , Radioactive Tracers , Rats , Thigh/radiation effects , Tumor Cells, Cultured , Xenograft Model Antitumor AssaysABSTRACT
Determination of urolith mineral composition is critical for management of urolithiasis in dogs and cats. Using computed tomography, urolith physical density, and hence chemical composition, can be quantified using mean beam attenuation measurements (Hounsfield units; HU). This study was designed to establish in vitro reference ranges for three types of compositionally pure uroliths retrieved from dogs. Sixty-six canine uroliths (22 uric acid, 21 calcium oxalate, 14 struvite, nine mixed or compound) were placed in a phantom array. Uroliths were scanned at 120 kVp, 200 mA, and 80 kVp, 200 mA. The region of interest (ROI) for mean HU calculation was determined using two techniques, and reference ranges were calculated for each kVp using either ROI technique. HU for urolith types of pure composition were statistically different (Wilcoxon's two-sample test, P < 0.0083 [Bonferonni correction with six comparisons for total P < 0.05]) using both ROI techniques at either kVp. Struvite uroliths were not statistically different from mixed or compound uroliths. The accuracy for determination of composition of pure uroliths ranged from 86% to 93%; the prediction accuracy for each urolith mineral type and for all uroliths in general was highest when the ROI was hand-drawn just within the visible urolith border at 80 kVp. Technique of ROI determination and kVp that yielded the highest sensitivity, specificity, and positive and negative predictive values varied for each urolith type. Therefore, in this study, HU could be used to differentiate three types of uroliths of pure mineral composition in vitro. Further studies are needed to determine the predictive value of HU in vivo.
