Diagnostic accuracy of stereotactic brain biopsy for intracranial neoplasia in dogs: Comparison of biopsy, surgical resection, and necropsy specimens

T2-FLAIR imaging-based radiomic features for predicting early postoperative recurrence of grade II gliomas

Aim: To develop and validate a T2-weighted-fluid attenuated inversion recovery (T2-FLAIR) images-based radiomics model for predicting early postoperative recurrence (within 1 year) in patients with low-grade gliomas (LGGs).Methods: A retrospective analysis was performed by collecting clinical, pathological and magnetic resonance imaging (MRI) data from patients with LGG between 2017 and 2022. Regions of interest were delineated and radiomic features were extracted from T2-FLAIR images using 3D-Slicer software. To minimize redundant features, the Least Absolute Shrinkage and Selection Operator (LASSO) regression algorithm was used. Patients were categorized into two groups based on recurrence status: the recurrence group (RG) and the non-recurrence group (NRG). Radiomic features were used to develop models using three machine learning approaches: logistic regression (LR), random forest (RF) and support vector machine (SVM). The performance of the radiomic features was validated using fivefold cross-validation.Results: After rigorous screening, 105 patients met the inclusion criteria, and five radiomic features were identified. After 5-folds cross-validation, the average areas under the curves for LR, RF and SVM were 0.813, 0.741 and 0.772, respectively.Conclusion: T2-FLAIR-based radiomic features effectively predicted early recurrence in postoperative LGGs.

Biopsy of Brain Lesions

Brain biopsy is essential for accurate diagnosis but is frequently avoided in veterinary medicine because of doubts about its safety, reliability, and clinical value. Data available from human and veterinary investigations suggest that such doubts are largely unwarranted. Many devices are available to guide minimally invasive biopsy but some can be costly to purchase and use, which can be problematic in veterinary medicine. Nowadays, costs can be substantially reduced by using 3-dimensional-printed guides.

Common Neurologic Diseases in Geriatric Dogs

The increase in the canine geriatric population means that veterinarians are more often confronted with diseases that are more prevalent in patients in this age group. As in other organ systems, degenerative, neoplastic, and vascular diseases are the most prevalent neurologic disorders in older dogs. A neurological disease in an older dog poses a challenge for the clinician due to the presence of concomitant diseases and age-related changes that make it difficult to interpret the neurological examination. In addition, given the age of the patients, some owners do not allow advanced imaging tests, and it is necessary to establish the most likely presumptive diagnosis to initiate treatment. Although many of these diseases can cause clinical signs that can be very upsetting, some of them can be managed with symptomatic therapy and have a good prognosis, such as idiopathic vestibular syndrome. Moreover, advances in and the greater availability of therapeutic options such as surgery and radiation therapy may increase survival and quality of life in diseases with a more serious prognosis, such as tumours. The aim of this review is to summarize the clinical presentation, diagnosis, and treatment of the more frequent diseases affecting the central nervous systems of geriatric dogs.

The T2-FLAIR mismatch sign as an imaging biomarker for oligodendrogliomas in dogs

BACKGROUND

In humans, the T2-weighted (T2W)-fluid-attenuated inversion recovery (FLAIR) mismatch sign (T2FMM) is a specific imaging biomarker for the isocitrate dehydrogenase 1 (IDH1)-mutated, 1p/19q non-codeleted low-grade astrocytomas (LGA). The T2FMM is characterized by a homogeneous hyperintense T2W signal and a hypointense signal with a hyperintense peripheral rim on FLAIR sequences. In gliomas in dogs, the T2FMM has not been described.

HYPOTHESES/OBJECTIVES

In dogs with focal intra-axial brain lesions, T2FMM will discriminate gliomas from other lesions. The T2FMM will be associated with the LGA phenotype and presence of microcysts on histopathology. Interobserver agreement for T2FMM magnetic resonance imaging (MRI) features will be high.

ANIMALS

One hundred eighty-six dogs with histopathologically diagnosed focal intra-axial lesions on brain MRI including oligodendrogliomas (n = 90), astrocytomas (n = 47), undefined gliomas (n = 9), cerebrovascular accidents (n = 33), and inflammatory lesions (n = 7).

METHODS

Two blinded raters evaluated the 186 MRI studies and identified cases with the T2FMM. Histopathologic and immunohistochemical slides of T2FMM cases were evaluated for morphologic features and IDH1-mutations and compared to cases without the T2FMM. Gene expression analyses were performed on a subset of oligodendrogliomas (n = 10) with and without T2FMM.

RESULTS

The T2FMM was identified in 14/186 (8%) of MRI studies, and all dogs with T2FMM had oligodendrogliomas (n = 12 low-grade [LGO], n = 2 high-grade [HGO]; P < .001). Microcystic change was significantly associated with the T2FMM (P < .00001). In oligodendrogliomas with T2FMM, IDH1-mutations or specific differentially expressed genes were not identified.

CONCLUSION AND CLINICAL IMPORTANCE

The T2FMM can be readily identified on routinely obtained MRI sequences. It is a specific biomarker for oligodendroglioma in dogs, and was significantly associated with non-enhancing LGO.

Volumetric assessment and longitudinal changes of subcortical structures in formalinized Beagle brains

High field MRI is an advanced technique for diagnostic and research purposes on animal models, such as the Beagle dog. In this context, studies on neuroscience applications, e.g. aging and neuro-pathologies, are currently increasing. This led to a need for reference values, in terms of volumetric assessment, for the structures typically involved. Nowadays, several canine brain MRI atlases have been provided. However, no reports are available regarding the measurements’ reproducibility and little is known about the effect of formalin on MRI segmentation. Here, we assessed the segmentation variability of selected structures among operators (two operators segmented the same data) in a sample of 11 Beagle dogs. Then, we analyzed, for one Beagle dog, the longitudinal volumetric changes of these structures. We considered four conditions: in vivo, post mortem (after euthanasia), ex vivo (brain extracted and studied after 1 month in formalin, and after 12 months). The MRI data were collected with a 3 T scanner. Our findings suggest that the segmentation procedure was overall reproducible since only slight statistical differences were detected. In the post mortem/ ex vivo comparison, most structures showed a higher contrast, thereby leading to greater reproducibility between operators. We observed a net increase in the volume of the studied structures. This could be justified by the intrinsic relaxation time changes observed because of the formalin fixation. This led to an improvement in brain structure visualization and segmentation. To conclude, MRI-based segmentation seems to be a useful and accurate tool that allows longitudinal studies on formalin-fixed brains.

Bioactivity of Biomass and Crude Exopolysaccharides Obtained by Controlled Submerged Cultivation of Medicinal Mushroom Trametes versicolor

The aim of this study is to characterize the bioactivity of mycelial biomass and crude exopolysaccharides (EPS) produced by Trametes versicolor NBIMCC 8939 and to reveal its nutraceutical potential. The EPS (1.58 g/L) were isolated from a culture broth. The macrofungal biomass was rich in protein, insoluble dietary fibers and glucans. The amino acid composition of the biomass was analyzed and 18 amino acids were detected. Three mycelial biomass extracts were prepared and the highest total polyphenol content (16.11 ± 0.14 mg GAE/g DW) and the total flavonoid content (5.15 ± 0.03 mg QE/g DW) were found in the water extract. The results indicated that the obtained EPS were heteropolysaccharides with glucose as the main building monosaccharide and minor amounts of mannose, xylose, galactose, fucose and glucuronic acid. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the complex structure of the crude EPS. Five probiotic lactic acid bacteria strains were used for the determination of the prebiotic effect of the crude EPS. The anti-inflammatory potential was tested in vitro using cell line HT-29. The significant decrease of IL-1 and IL-8 and increase of TGF-beta expression revealed anti-inflammatory potential of the crude exopolysaccharides from T. versicolor.

Case Report: Clinical Use of a Patient-Individual Magnetic Resonance Imaging-Based Stereotactic Navigation Device for Brain Biopsies in Three Dogs

Three-dimensional (3D) printing techniques for patient-individual medicine has found its way into veterinary neurosurgery. Because of the high accuracy of 3D printed specific neurosurgical navigation devices, it seems to be a safe and reliable option to use patient-individual constructions for sampling brain tissue. Due to the complexity and vulnerability of the brain a particularly precise and safe procedure is required. In a recent cadaver study a better accuracy for the 3D printed MRI-based patient individual stereotactic brain biopsy device for dogs is determined compared to the accuracies of other biopsy systems which are currently used in veterinary medicine. This case report describes the clinical use of this 3D printed MRI-based patient individual brain biopsy device for brain sampling in three dogs. The system was characterized by a simple handling. Furthermore, it was an effective and reliable tool to gain diagnostic brain biopsy samples in dogs with no significant side effects.

Comparison of linear and volumetric criteria for the determination of therapeutic response in dogs with intracranial gliomas

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.

Clinical use of a new frameless optical neuronavigation system for brain biopsies: 10 cases (2013-2020)

OBJECTIVES

The aim of the retrospective study was to describe the brain biopsy procedure using a new frameless optical neuronavigation system and to report diagnostic yield and complications associated with the procedure.

MATERIALS AND METHODS

The medical records for all dogs with forebrain lesions that underwent brain biopsy with a frameless optical neuronavigation system in a single referral hospital between 2013 and 2020 were retrospectively analysed. Following data were collected: signalment, neurological signs, diagnostic findings, number of brain biopsy samples, sampled region, complications, duration of hospitalisation, whether the samples were diagnostic and histopathological diagnoses. The device consists of a computer workstation with navigation software, an infrared camera, patient tracker and reflective instruments. The biopsy needle was equipped with reflective spheres, so the surgeon could see the position of the needle during sampling the intracranial lesion free handed through a mini-burr hole.

RESULTS

Ten dogs were included. Absolute diagnostic yield based on specific histopathological diagnosis was 73.9%. Three dogs had immune-mediated necrotizing encephalitis, two dogs showed a necrotizing leukoencephalitis and two dogs a meningoencephalitis of unknown origin. In two dogs, the brain specimen showed unspecific changes. In one dog, the samples were non-diagnostic. Seven dogs showed no neurological deterioration, one dog mild temporary ataxia and two dogs died within 36 hours post brain biopsy.

CLINICAL SIGNIFICANCE

In these 10 dogs, the frameless optical neuronavigation system employed was useful to gain diagnostic brain biopsy samples. Considering the mortality rate observed, further studies are needed to confirm the safety of this procedure and prove its actual clinical effectiveness.

Feasability of a Frameless Brain Biopsy System for Companion Animals Using Cone-Beam CT-Based Automated Registration

The aim of the present study was to evaluate the use of a novel intraoperative cone-beam computed tomography (CBCT)-based automated registration system for frameless stereotactic brain biopsy in companion animals. An experimental cadaveric study evaluated thalamic and piriform lobe target site needle placement error in three dogs and three cats without a history of intracranial disease. Diagnostic accuracy and diagnostic yield were prospectively evaluated in twenty-four client-owned dogs and four cats with intracranial disease. Twenty-one procedures were performed post mortem (eighteen dogs and three cats), and seven biopsy procedures were performed in alive patients (six dogs and one cat). Procedural duration was evaluated in ten post mortem and four living patients. Outcome was evaluated in six dogs and one cat. In dogs, the calculated median needle placement error was 1.8 mm (range 0.71–2.84 mm) and 1.53 mm (range 1.45–1.99 mm) for piriform lobe and thalamus target sites, respectively. In cats, the calculated median needle placement error was 0.79 mm (range 0.6–1.91 mm) for the piriform lobe target site and 1.29 mm (range 0.47–2.69 mm) for the thalamic target site. The diagnostic yield was 96.4% (95% CI 0.81–0.99), the diagnostic accuracy was 94.4% (95% CI 0.72–0.99). Median total procedural duration for post mortem biopsies was 57.5 min (range 41–69 min). Median total procedural duration for intra vitam biopsies was 122.5 min (range 103–136 min). Three dogs were discharged 1 day after biopsy and one dog after 6 days. Two dogs and one cat were euthanized 24 and 48 h after biopsy. Intraoperative CBCT-based automated image registration for frameless stereotactic biopsies in companion animals is capable of providing diagnostic brain biopsy specimens independent of skull size and morphology with diagnostic yield and accuracy comparable to published values for diverse frameless and frame-based stereotaxy systems used in veterinary medicine. Duration of the procedure is not negatively affected and within the published range with other systems. Mobile intraoperative CBCT-based registration combined with neuronavigation delivers diagnostic brain biopsies in companion animals.

A Radiomics Model for Predicting Early Recurrence in Grade II Gliomas Based on Preoperative Multiparametric Magnetic Resonance Imaging

Objective

This study aimed to develop a radiomics model to predict early recurrence (<1 year) in grade II glioma after the first resection.

Methods

The pathological, clinical, and magnetic resonance imaging (MRI) data of patients diagnosed with grade II glioma who underwent surgery and had a recurrence between 2017 and 2020 in our hospital were retrospectively analyzed. After a rigorous selection, 64 patients were eligible and enrolled in the study. Twenty-two cases had a pathologically confirmed recurrent glioma. The cases were randomly assigned using a ratio of 7:3 to either the training set or validation set. T1-weighted image (T1WI), T2-weighted image (T2WI), and contrast-enhanced T1-weighted image (T1CE) were acquired. The minimum-redundancy-maximum-relevancy (mRMR) method alone or in combination with univariate logistic analysis were used to identify the most optimal predictive feature from the three image sequences. Multivariate logistic regression analysis was then used to develop a predictive model using the screened features. The performance of each model in both training and validation datasets was assessed using a receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA).

Results

A total of 396 radiomics features were initially extracted from each image sequence. After running the mRMR and univariate logistic analysis, nine predictive features were identified and used to build the multiparametric radiomics model. The model had a higher AUC when compared with the univariate models in both training and validation data sets with an AUC of 0.966 (95% confidence interval: 0.949–0.99) and 0.930 (95% confidence interval: 0.905–0.973), respectively. The calibration curves indicated a good agreement between the predictable and the actual probability of developing recurrence. The DCA demonstrated that the predictive value of the model improved when combining the three MRI sequences.

Conclusion

Our multiparametric radiomics model could be used as an efficient and accurate tool for predicting the recurrence of grade II glioma.

Outcome After Radiation Therapy in Canine Intracranial Meningiomas or Gliomas

AIM

To characterize a group of dogs diagnosed with meningioma or glioma treated with radiation therapy and assess the clinical impact of diagnosis and radiation protocol on survival time.

PATIENTS AND METHODS

Canine patient records from a single veterinary referral hospital, between 2011 and 2015, were searched for intracranial tumour cases treated with radiation therapy, as a sole modality. Thirty-two dogs were included.

RESULTS

Median survival times were 524 days [95% confidence interval (CI)=287-677] in total, 512 days (95% CI=101-682) for the glioma group and 536 days (95% CI=249-677) for the meningioma group. No significant difference in survival was detected when using a definitive or a palliative protocol (p=0.130), nor other prognostic factors were found.

CONCLUSION

Our results highlight the efficacy of radiation therapy in the treatment of canine meningioma, as well as glioma, suggesting a change in the current perception of the response of glial tumours to radiation.

Feasibility and accuracy of 3D printed patient-specific skull contoured brain biopsy guides

Objective

Design 3D printed skull contoured brain biopsy guides (3D‐SCGs) from computed tomography (CT) or T1‐weighted magnetic resonance imaging (T1W MRI).

Study Design

Feasibility study.

Sample Population

Five beagle dog cadavers and two client‐owned dogs with brain tumors.

Methods

Helical CT and T1W MRI were performed on cadavers. Planned target point was the head of the caudate nucleus. Three‐dimensional‐SCGs were created from CT and MRI using commercially available open‐source software. Using 3D‐SCGs, biopsy needles were placed into the caudate nucleus in cadavers, and CT was performed to assess needle placement accuracy, followed by histopathology. Three‐dimensional‐SCGs were then created and used to perform in vivo brain tumor biopsies.

Results

No statistical difference was found between the planned target point and needle placement. Median needle placement error for all planned target points was 2.7 mm (range: 0.86–4.5 mm). No difference in accuracy was detected between MRI and CT‐designed 3D‐SCGs. Median needle placement error for the CT was 2.8 mm (range: 0.86–4.5 mm), and 2.2 mm (range: 1.7–2.7 mm) for MRI. Biopsy needles were successfully placed into the target in the two dogs with brain tumors and biopsy was successfully acquired in one dog.

Conclusion

Three‐dimensional‐SCGs designed from CT or T1W MRI allowed needle placement within 4.5 mm of the intended target in all procedures, resulting in successful biopsy in one of two live dogs.

Clinical Significance

This feasibility study justifies further evaluation of 3D‐SCGs as alternatives in facilities that do not have access to stereotactic brain biopsy.

Canine presumed glial brain tumours treated with radiotherapy: Is there an inferior outcome in tumours contacting the subventricular zone?

Post-treatment outcome in canine glial tumours is described with a broad range of survival times between 2 and 28 months. After surgery or radiation therapy, the tumours may progress locally or spread within the central nervous system. It is unknown if tumour- or patient-specific factors influence prognosis. In humans, glioblastoma involving the subventricular zone has been found to recur distantly, with shortened time to progression and overall survival. We included 32 dogs irradiated for a presumptive primary glial brain tumour in this retrospective cohort study. Tumours were grouped relative to subventricular zone contact and overt ventricular invasion assessing pre-treatment magnetic resonance images. Median time to progression (TTP) for all cases was 534 days (95%CI, 310-758), with a significantly shorter TTP in dogs with lesions at the subventricular zone (median TTP, 260 vs. 687 days; p = .049). Tumours at the subventricular zone progressed more often (p = .001), and more likely as CNS-metastasis (52.9% vs. 13.3%, p = .028). Median overall survival (OS) was 489 days (95%CI, 147-831) and median tumour-specific survival 609 days (95%CI, 382-835). Involvement of the subventricular zone was significantly associated with a shorter tumour-specific survival (median, 306 vs. 719 days; p = .044). Glial tumours contacting the subventricular zone in dogs have a shorter tumour-specific survival and a higher rate of progression and CNS-metastasis. Despite local tumour control, metastasis must be considered and should prompt further treatment approaches.

Fluctuation of Clinical Signs With Near-Syncopal Episodes in a Dog With Gliomatosis Cerebri: A Diagnostic Challenge

A 2-year-old Bull Mastiff cross Boxer neutered male dog was evaluated because of 2-month history of non-progressive right head tilt and mild vestibular ataxia. MRI of the brain revealed a faint T2W, FLAIR, DWI and ADC heterogenous hyperintense and T1W isointense intra-axial lesion with indistinct margins at the level of the pons and medulla oblongata. The lesion did not show any susceptibility artefact on T2* GRE images or contrast enhancement and CSF analysis was normal. Analysis of the spectra from MRS of the thalamus not promptly available at the time of the MRI study revealed a decreased level of NAA, as seen in people with gliomatosis cerebri. The dog represented 3 weeks later and, on this occasion, displayed left-sided head tilt, left-sided postural reaction deficits and near-syncopal episodes associated with state of confusion. Repeated MRI revealed a larger non-enhancing intra-axial lesion with a more hyperintense signal than previously described. CSF was normal and PCR of CSF for infectious diseases was negative. Thoracic and abdominal computed tomography did not reveal any primary or metastatic process. Immunosuppressive treatment was attempted and the dog remained stable over 5 days, then developed generalized tonic-clonic seizures which led to status epilepticus and death. Histopathology supported the diagnosis of gliomatosis cerebri. Gliomatosis cerebri remains difficult to diagnose ante-mortem, due to the broad age of onset and the variable duration and wide range of clinical signs. The mismatch between MRI findings and clinical presentation, the fluctuating clinical signs with near-syncopal episodes associated with a state of confusion, the presence of an infiltrative brain disease as depicted on MR imaging and a normal CSF analysis, should prompt the clinician to consider possible diagnosis of a widespread infiltrative neoplasm. Although, MRS may help narrow the differential diagnosis in favor of a neoplastic lesion, the overall prognosis remains poor.

Risk factors for adverse events occurring after recovery from stereotactic brain biopsy in dogs with primary intracranial neoplasia

BACKGROUND

Stereotactic brain biopsy (SBB) allows for histopathologic diagnosis of brain tumors. Adverse events (AE) occur in 5 to 29% of dogs after SBB, but risk factors associated with developing AE are poorly described.

OBJECTIVE

Identify clinicopathologic, diagnostic imaging, or procedural variables that are associated with AE in dogs after SBB.

ANIMALS

Twenty-nine dogs with brain tumors.

METHODS

Retrospective, case-control study. Dogs had laboratory investigations performed before SBB, as well as clinical examinations and diagnostic imaging of the brain before and after SBB. Cases experienced AE after SBB including transient exacerbation of preexisting neurologic deficits, transient new deficits, or permanent neurologic deficits. Controls had SBB performed without AE. Fisher's exact and Student's t tests were used to examine associations between the postulated risk factors and AE.

RESULTS

Adverse events occurred in 8/29 (27%) dogs, and 7/8 AE (88%) were transient. Cases were significantly more likely to have T2W-heterogenous tumors (88 versus 38%; P = .04) and lower platelet counts (194.75 ± 108.32 versus 284.29 ± 68.54 ×103 /mm3 , P = .006). Dogs with gradient echo signal voids present on baseline imaging were significantly more likely to have hemorrhage present after biopsy, and 7/8 (88%) of cases had hemorrhage on imaging after SBB.

CONCLUSION AND CLINICAL IMPORTANCE

Twenty-seven percent of dogs undergoing SBB experience AE, with the majority of AE resolving with 1 week. Platelet counts should be ≥185 000/mm3 to minimize risk of SBB-associated AE. Observation of intracranial hemorrhage after biopsy can have important clinical implications, as this was observed in 88% of dogs with AE.

Radiomics Features Predict CIC Mutation Status in Lower Grade Glioma

MRI in combination with genomic markers are critical in the management of gliomas. Radiomics and radiogenomics analysis facilitate the quantitative assessment of tumor properties which can be used to model both molecular subtype and predict disease progression. In this work, we report on the Drosophila gene capicua (CIC) mutation biomarker effects alongside radiomics features on the predictive ability of CIC mutation status in lower-grade gliomas (LGG). Genomic data of lower grade glioma (LGG) patients from The Cancer Genome Atlas (TCGA) (n = 509) and corresponding MR images from TCIA (n = 120) were utilized. Following tumor segmentation, radiomics features were extracted from T1, T2, T2 Flair, and T1 contrast enhanced (CE) images. Lasso feature reduction was used to obtain the most important MR image features and then logistic regression used to predict CIC mutation status. In our study, CIC mutation rarely occurred in Astrocytoma but has a high probability of occurrence in Oligodendroglioma. The presence of CIC mutation was found to be associated with better survival of glioma patients (p < 1e−4, HR: 0.2445), even with co-occurrence of IDH mutation and 1p/19q co-deletion (p = 0.0362, HR: 0.3674). An eleven-feature model achieved glioma prediction accuracy of 94.2% (95% CI, 94.03–94.38%), a six-feature model achieved oligodendroglioma prediction accuracy of 92.3% (95% CI, 91.70–92.92%). MR imaging and its derived image of gliomas with CIC mutation appears more complex and non-uniform but are associated with lower malignancy. Our study identified CIC as a potential prognostic factor in glioma which has close associations with survival. MRI radiomic features could predict CIC mutation, and reflect less malignant manifestations such as milder necrosis and larger tumor volume in MRI and its derived images that could help clinical judgment.

A pilot study of optical neuronavigation-guided brain biopsy in the horse using anatomic landmarks and fiducial arrays for patient registration

Background

Optical neuronavigation‐guided intracranial surgery has become increasingly common in veterinary medicine, but its use has not yet been described in horses.

Objectives

To determine the feasibility of optical neuronavigation‐guided intracranial biopsy procedures in the horse, compare the use of the standard fiducial array and anatomic landmarks for patient registration, and evaluate surgeon experience.

Animals

Six equine cadaver heads.

Methods

Computed tomography images of each specimen were acquired, with the fiducial array rigidly secured to the frontal bone. Six targets were selected in each specimen. Patient registration was performed separately for 3 targets using the fiducial array, and for 3 targets using anatomic landmarks. In lieu of biopsy, 1 mm diameter wire seeds were placed at each target. Postoperative images were coregistered with the planning scan to calculate Euclidian distance from the tip of the seed to the target.

Results

No statistical difference between registration techniques was identified. The impact of surgeon experience was examined for each technique using a Mann‐Whitney U test. The experienced surgeon was significantly closer to the intended target (median = 2.52 mm) than were the novice surgeons (median = 6.55 mm) using the fiducial array (P = .001). Although not statistically significant (P = .31), for the experienced surgeon the median distance to target was similar when registering with the fiducial array (2.47 mm) and anatomic landmarks (2.58 mm).

Conclusions and Clinical Importance

Registration using both fiducial arrays and anatomic landmarks for brain biopsy using optical neuronavigation in horses is feasible.

Accuracy of a magnetic resonance imaging-based 3D printed stereotactic brain biopsy device in dogs

BACKGROUND

Brain biopsy of intracranial lesions is often necessary to determine specific therapy. The cost of the currently used stereotactic rigid frame and optical tracking systems for brain biopsy in dogs is often prohibitive or accuracy is not sufficient for all types of lesion.

OBJECTIVES

To evaluate the application accuracy of an inexpensive magnetic resonance imaging-based personalized, 3D printed brain biopsy device.

ANIMALS

Twenty-two dog heads from cadavers were separated into 2 groups according to body weight (<15 kg, >20 kg).

METHODS

Experimental study. Two target points in each cadaver head were used (target point 1: caudate nucleus, target point 2: piriform lobe). Comparison between groups was performed using the independent Student's t test or the nonparametric Mann-Whitney U Test.

RESULTS

The total median target point deviation was 0.83 mm (range 0.09-2.76 mm). The separate median target point deviations for target points 1 and 2 in all dogs were 0.57 mm (range: 0.09-1.25 mm) and 0.85 mm (range: 0.14-2.76 mm), respectively.

CONCLUSION AND CLINICAL IMPORTANCE

This magnetic resonance imaging-based 3D printed stereotactic brain biopsy device achieved an application accuracy that was better than the accuracy of most brain biopsy systems that are currently used in veterinary medicine. The device can be applied to every size and shape of skull and allows precise positioning of brain biopsy needles in dogs.

Companion animal models of neurological disease

Clinical translation of novel therapeutics that improve the survival and quality of life of patients with neurological disease remains a challenge, with many investigational drug and device candidates failing in advanced stage clinical trials. Naturally occurring inherited and acquired neurological diseases, such as epilepsy, inborn errors of metabolism, brain tumors, spinal cord injury, and stroke occur frequently in companion animals, and many of these share epidemiologic, pathophysiologic and clinical features with their human counterparts. As companion animals have a relatively abbreviated lifespan and genetic background, are immunocompetent, share their environment with human caregivers, and can be clinically managed using techniques and tools similar to those used in humans, they have tremendous potential for increasing the predictive value of preclinical drug and device studies. Here, we review comparative features of spontaneous neurological diseases in companion animals with an emphasis on neuroimaging methods and features, illustrate their historical use in translational studies, and discuss inherent limitations associated with each disease model. Integration of companion animals with naturally occurring disease into preclinical studies can complement and expand the knowledge gained from studies in other animal models, accelerate or improve the manner in which research is translated to the human clinic, and ultimately generate discoveries that will benefit the health of humans and animals.

Canine Primary Intracranial Cancer: A Clinicopathologic and Comparative Review of Glioma, Meningioma, and Choroid Plexus Tumors

In the dog, primary intracranial neoplasia represents ~2-5% of all cancers and is especially common in certain breeds including English and French bulldogs and Boxers. The most common types of primary intracranial cancer in the dog are meningioma, glioma, and choroid plexus tumors, generally occurring in middle aged to older dogs. Much work has recently been done to understand the characteristic imaging and clinicopathologic features of these tumors. The gross and histologic landscape of these tumors in the dog compare favorably to their human counterparts with many similarities noted in histologic patterns, subtype, and grades. Data informing the underlying molecular abnormalities in the canine tumors have only begun to be unraveled, but reveal similar pathways are mutated between canine and human primary intracranial neoplasia. This review will provide an overview of the clinicopathologic features of the three most common forms of primary intracranial cancer in the dog, delve into the comparative aspects between the dog and human neoplasms, and provide an introduction to current standard of care while also highlighting novel, experimental treatments that may help bridge the gap between canine and human cancer therapies.

Diagnostic accuracy of stereotactic brain biopsy for intracranial neoplasia in dogs: Comparison of biopsy, surgical resection, and necropsy specimens

Background

Stereotactic brain biopsy (SBB) is a technique that allows for definitive diagnosis of brain lesions. Little information is available regarding the diagnostic utility of SBB in dogs with intracranial diseases.

Objective

To investigate the diagnostic accuracy (DA) of SBB in dogs with brain tumors.

Animals

Thirty‐one client‐owned dogs that underwent SBB followed by surgical resection or necropsy examinations.

Methods

Retrospective observational study. Two pathologists blinded to SBB and reference standard diagnoses reviewed histologic specimens and typed and graded tumors according to World Health Organization and revised canine glioma classification criteria. Agreement between tumor type and grade from SBB were compared to reference standards and assessed using kappa statistics. Patient and technical factors associated with agreement also were examined.

Results

Stereotactic brain biopsy specimens were obtained from 24 dogs with gliomas and 7 with meningiomas. Tumor type agreement between SBB and the reference standard was observed in 30/31 cases (κ = 0.95). Diagnostic concordance was perfect for meningiomas. Grade agreement among gliomas was observed in 18/23 cases (κ = 0.47). Stereotactic brain biopsy underrepresented the reference standard glioma grade in cases with disagreement. The DA of SBB was 81%, with agreement noted in 56/69 biopsy samples. Smaller tumors and fewer SBB specimens obtained were significantly associated with diagnostic discordance.

Conclusions and Clinical Importance

The DA of SBB readily allows for the diagnosis of common brain tumors in dogs. Although glioma grade discordance was frequent, diagnoses obtained from SBB are sufficient to currently inform therapeutic decisions. Multiple SBB specimens should be collected to maximize DA.