Browsing by Author "Shinn, Richard Levon"

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    Comparison of linear and volumetric criteria for the determination of therapeutic response in dogs with intracranial gliomas
    Garcia Mora, Josefa Karina; Robertson, John L.; Hsu, Fang-Chi; Shinn, Richard Levon; Larson, Martha M.; Rylander, Christopher G.; Whitlow, Christopher T.; Debinski, Waldemar; Davalos, Rafael V.; Daniel, Gregory B.; Rossmeisl, John H. Jr. (Wiley, 2022-05)
    Background: Brain tumor therapeutic responses can be quantified from magnetic resonance images (MRI) using 1- (1D) and 2-dimensional (2D) linear and volumetric methods, but few studies in dogs compare these techniques. Hypotheses: Linear methods will be obtained faster, but have less agreement than volumetric measurements. Therapeutic response agreement will be highest with the total T2W tumor volumetric (TTV) method. Therapeutic response at 6-weeks will correlate with overall survival (OS). Animals: Forty-six dogs with intracranial gliomas. Methods: Prospective study. Three raters measured tumors using 1D and 2D linear, TTV, and contrast-enhancing volumetric (CEV) techniques on 143 brain MRI to determine agreement between methods, define therapeutic responses, and assess relations with OS. Results: Raters performed 1D the fastest (2.9 ± 0.57 minutes) and CEV slowest (17.8 ± 6.2 minutes). Inter- and intraobserver agreements were excellent (intraclass correlations ≥.91) across methods. Correlations between linear (1D vs 2D; ρ >.91) and volumetric (TTV vs CEV; ρ >.73) methods were stronger than linear to volumetric comparisons (ρ range,.26-.59). Incorporating clinical and imaging data resulted in fewer discordant therapeutic responses across methods. Dogs having partial tumor responses at 6 weeks had a lower death hazard than dogs with stable or progressive disease when assessed using 2D, CEV, and TTV (hazard ration 2.1; 95% confidence interval, 1.22-3.63; P =.008). Conclusions and Clinical Importance: One-dimensional, 2D, CEV, and TTV are comparable for determining therapeutic response. Given the simplicity, universal applicability, and superior performance of the TTV, we recommend its use to standardize glioma therapeutic response criteria.
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    Evaluation of Neurofilament Light Chain as a Biomarker in Dogs with Structural and Idiopathic Epilepsy
    Fowler, Kayla Marie (Virginia Tech, 2023-05-31)
    The objective of this prospective cohort study is to assess the use of neurofilament light chain (NfL) as a biomarker for diagnostic and therapeutic monitoring in dogs with idiopathic and structural epilepsy. A total of 50 dogs (36 idiopathic epilepsy and 14 structural epilepsy) were enrolled to contribute a total of 58 samples (52 serum and 6 cerebrospinal fluid (CSF)). Dogs diagnosed with structural epilepsy received magnetic resonance imaging (MRI). Dogs were grouped into acute seizures when they had a generalized seizure within the last 7 days and chronic seizures when they had no observed generalized seizures for the previous 30 days. Both serum and CSF NfL concentrations were measured using single molecule array technology (Simoa). The median serum concentration of NfL in dogs with structural epilepsy was 109 [11.4-741.3] pg/mL and 17.7 [5.8-188] pg/mL in dogs with idiopathic epilepsy regardless of the interictal interval. Serum NfL concentration was significantly increased in dogs with structural epilepsy when compared with dogs with idiopathic epilepsy (p < 0.001). There was no significant difference in NfL concentration in dogs with an interictal interval of 7 days compared to dogs with an interictal interval of 30 days. In dogs with seizures, serum NfL concentration may help discriminate between structural and idiopathic epilepsy. Future studies are needed to determine its role in differentiating true seizure events from seizure mimics.
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    Magnetization Transfer and Diffusion Tensor Imaging in Dogs with Intervertebral Disc Herniation
    Shinn, Richard Levon (Virginia Tech, 2020-07-14)
    Background: Quantitative imaging surrogates of myelin and axonal integrity using magnetization transfer and diffusion tensor imaging may provide beneficial prognostic details on long-term post-surgical recovery in dogs with spinal cord injury (SCI) secondary to intervertebral disc herniation (IVDH). Hypothesis: Magnetization transfer ratio (MTR), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) will be significantly different in patients with a successful outcome compared to patients with an unsuccessful outcome. Animals: 61 dogs with SCI secondary to IVDH were included in the final analysis. All dogs had to undergo surgical correction for SCI secondary to IVDH and be followed out for 12 weeks. Methods: Prospective cohort study. MTR, MD, AD, RD, and FA were calculated in dogs with SCI secondary to IVDH. A Wilcoxon signed-rank test was used to compare MTR, MD, AD, RD, and FA values between patients with a successful outcome and patients with an unsuccessful outcome. Statistical significance was set at p<0.05. For quantitative imaging surrogates with a significant relationship with outcome, a receiver operator characteristic (ROC) curve analysis was performed and the sensitivity and specificity for predicting successful outcome. Results: MTR (p=0.0013) was significantly lower in patients with a successful outcome compared to patients with an unsuccessful outcome. FA (p=0.435) was not significantly between groups. MD (p=0.0006), AD (p=0.0008) and RD (p=0.0002) were significantly higher in patients with a successful outcome compared to patients with an unsuccessful outcome. ROC curves were performed for MTR, AD and RD. If MTR was ≤ 53, AD ≥ 1.7 × 10-3mm2/s or RD ≥ 0.37 × 10-3 mm2/s, this resulted in a sensitivity of 96.3% and specificity of 100 in predicting a successful outcome. Conclusion and clinical relevance: MTR, MD, AD, and RD were helpful in predicting successful outcome in canine patients with surgically treated SCI secondary to IVDH. A larger cohort is needed for further evaluation.