Computed Tomographic Assessment of Individual Paranasal Sinus Compartment and Nasal Conchal Bulla Involvement in 300 Cases of Equine Sinonasal Disease

Three-Dimensional Segmentation of Equine Paranasal Sinuses in Multidetector Computed Tomography Datasets: Preliminary Morphometric Assessment Assisted with Clustering Analysis

The paranasal sinuses, a bilaterally symmetrical system of eight air-filled cavities, represent one of the most complex parts of the equine body. This study aimed to extract morphometric measures from computed tomography (CT) images of the equine head and to implement a clustering analysis for the computer-aided identification of age-related variations. Heads of 18 cadaver horses, aged 2-25 years, were CT-imaged and segmented to extract their volume, surface area, and relative density from the frontal sinus (FS), dorsal conchal sinus (DCS), ventral conchal sinus (VCS), rostral maxillary sinus (RMS), caudal maxillary sinus (CMS), sphenoid sinus (SS), palatine sinus (PS), and middle conchal sinus (MCS). Data were grouped into young, middle-aged, and old horse groups and clustered using the K-means clustering algorithm. Morphometric measurements varied according to the sinus position and age of the horses but not the body side. The volume and surface area of the VCS, RMS, and CMS increased with the age of the horses. With accuracy values of 0.72 for RMS, 0.67 for CMS, and 0.31 for VCS, the possibility of the age-related clustering of CT-based 3D images of equine paranasal sinuses was confirmed for RMS and CMS but disproved for VCS.

Comparison of equine paranasal sinus trephination complications and outcome following standing computed tomography, radiography and sinoscopy guided approaches for the treatment of sinusitis

OBJECTIVE

The recent availability of standing computed tomography (CT) for equine paranasal sinus disease has enhanced diagnosis and enabled more targeted surgery compared to radiography and sinoscopy. To date, there have been no studies which have critically evaluated the benefit of preoperative CT versus radiography and sinoscopy on complications and outcome in horses undergoing sinus trephination.

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 229 equids.

METHODS

The medical records of equids (229) presented for sinusitis treated via trephination that had CT, radiography and/or sinoscopy at time of surgery between 2009 and 2022 were reviewed. Outcome and complications were evaluated for six different pre- and intraoperative imaging modalities.

RESULTS

The six groups did not differ in demographics or disease category, though equids with less weight (p = .0179) and shorter disease duration (p = .0075) were more likely to have radiography and sinoscopy based surgical planning. Short-term postoperative complications occurred in 30.1% and were higher in groups using preoperative CT imaging (p = .01), with hemorrhage being the most common surgical complication. Following initial trephination surgery, 57.0% (127/223) of cases resolved and there was no difference between the imaging groups. Final resolution after follow-up medical or surgical treatment increased to 94.6% (211/223) and was not different between the imaging groups or between primary or secondary sinusitis. Additional nasal fenestrations to improve sinonasal drainage, maxillary septal bulla fenestrations and trephinations to treat nasal conchal bullae were made in the CT groups.

CLINICAL SIGNIFICANCE

CT provided additional diagnostic information and enabled different surgical approaches but did not improve resolution in this study population.

Three-Dimensional Segmentation Assisted with Clustering Analysis for Surface and Volume Measurements of Equine Incisor in Multidetector Computed Tomography Data Sets

Dental diagnostic imaging has progressed towards the use of advanced technologies such as 3D image processing. Since multidetector computed tomography (CT) is widely available in equine clinics, CT-based anatomical 3D models, segmentations, and measurements have become clinically applicable. This study aimed to use a 3D segmentation of CT images and volumetric measurements to investigate differences in the surface area and volume of equine incisors. The 3D Slicer was used to segment single incisors of 50 horses' heads and to extract volumetric features. Axial vertical symmetry, but not horizontal, of the incisors was evidenced. The surface area and volume differed significantly between temporary and permanent incisors, allowing for easy eruption-related clustering of the CT-based 3D images with an accuracy of >0.75. The volumetric features differed partially between center, intermediate, and corner incisors, allowing for moderate location-related clustering with an accuracy of >0.69. The volumetric features of mandibular incisors' equine odontoclastic tooth resorption and hypercementosis (EOTRH) degrees were more than those for maxillary incisors; thus, the accuracy of EOTRH degree-related clustering was >0.72 for the mandibula and >0.33 for the maxilla. The CT-based 3D images of equine incisors can be successfully segmented using the routinely achieved multidetector CT data sets and the proposed data-processing approaches.

Use of a novel helical fan beam imaging system for computed tomography of the head and neck in sedated standing horses: 120 cases (2019–2020)

OBJECTIVE

To evaluate the diagnostic capabilities of a novel helical fan beam CT system used for imaging of horses with clinical problems of the head and neck.

ANIMALS

120 horses.

PROCEDURES

Medical records were reviewed of horses presented for CT of the head or neck at 2 university hospitals. The following data were recorded: age, sex, breed, presenting complaint, sedation used for imaging, scanning time, procedure time, other diagnostic imaging methods performed, imaging diagnosis, clinical diagnosis, and complications during imaging.

RESULTS

Quarter Horses and Warmbloods were the most common breeds, and the most common complaint was nasal discharge. The head (101/120 [84%] horses) was scanned most frequently, and the most common diagnoses were primary dental disease and a space-occupying lesion of the paranasal sinuses. Nuchal bursitis was the most common imaging diagnosis in the neck region. Procedure time ranged from 20 to 45 minutes with a scanning time of 30 to 40 seconds. No complications with horse sedation occurred, and horses tolerated scanning well. An imaging diagnosis was more frequently achieved with CT (109/120 [91%] horses) than with planar digital radiography (23/61 [38%] horses).

CLINICAL RELEVANCE

The helical fan beam CT system had fast scanning times and could be used safely for routine imaging of the teeth and sinuses in horses. The caudal extent of scanning in the neck region was limited by the shape of the horse’s neck and thorax.

The Role of Computed Tomography in Imaging Non-neurologic Disorders of the Head in Equine Patients

Computed tomography (CT) imaging of the head in equine patients is now commonly performed as CT scanners are more readily available. Head CT has proven valuable in evaluating spatially complex anatomic structures, where radiographic superimposition, or restricted access via endoscopy or ultrasound, limit complete evaluation of the disease process. Head CT has been demonstrated to be incredibly valuable in the evaluation of dental and paranasal sinus disease, disease of the hyoid apparatus and ear, and in evaluation of skull trauma. CT is an excellent modality for assessment of both osseous and soft tissue structures; however, evaluation of complex vascular anatomy and determination of tissue viability is limited without the use of contrast agents. Therefore, various contrast agent protocols including intravenous and intraarterial iodinated contrast administration techniques have been established. CT also has limitations in the evaluation of brain and spinal cord disease, for which magnetic resonance imaging (MRI) has major advantages. Head CT images are most commonly evaluated in transverse planes. However, standard multiplanar reconstructions of the head including dorsal and parasagittal planes improve the understanding of spatially complex disease processes. These reconstructions can be crucial for accurate identification of diseased teeth and determination of the extent and severity of osseous and paranasal sinus disease. Head CT examinations are becoming an increasingly important diagnostic tool in the evaluation of horses with head disorders, and CT imaging findings are an important aspect in the clinical decision-making process. The following review discusses the indications, benefits, and technical considerations for the use of computed tomography (CT) in evaluating non-neurologic head pathologies in equine patients.

Multidetector CT and cone-beam CT have substantial agreement in detecting dental and sinus abnormalities in equine cadaver heads

The performance of cone-beam CT (CBCT) systems compared to conventional helical multidetector CT (MDCT) imaging of the equine head is unknown. The aim of this prospective, method-comparison study was to compare the ability of CBCT and MDCT to detect abnormalities in equine cadaver heads. Eleven equine cadaver heads were scanned using a CBCT scanner and a 64-slice MDCT scanner. Consensus evaluations for CBCT and MDCT scans were performed by three observers. Identified abnormalities were grouped into subcategories with a focus on dental abnormalities. Kappa agreement values between detected abnormalities for CBCT and MDCT methods were calculated. Of 468 teeth evaluated, 122 (26.1%) were found to have abnormalities (including in 58 infundibula and 7 pulps) using MDCT and 105 (22.4%) were found to have abnormalities (including in 52 infundibula and 2 pulps) using CBCT. The agreement between CBCT and MDCT was almost perfect for overall detection of dental abnormalities (k = 0.90) with k = 1 for diastema k = 0.95 for clinical crown abnormalities, and k = 0.93 for infundibular abnormalities. However, the detection of pulp changes by CBCT was only moderate k = 0.44. Increased scatter radiation, non-calibrated Hounsfield Unit and artefacts in CBCT images made accurate identification of the pulp density difficult. In conclusion, CBCT results were similar to conventional MDCT for the majority of dental abnormalities, however, pulp abnormalities were not reliably identified using CBCT, potentially limiting its clinical use for detecting endodontic disease in its current form. Further comparison with more cases with confirmed dental disease and studies in clinical cases are warranted.

A long-term study of sinoscopic treatment of equine paranasal sinus disease: 155 cases (2012-2019)

BACKGROUND

There is little objective information concerning the intra- and post-operative complications or the long-term outcome of sinoscopic treatment of equine sinus disorders.

OBJECTIVES

To document the long-term outcome, including intra-operative complications, reasons for treatment failure and other complications, in horses undergoing standing sinoscopic treatment of sinus disorders.

STUDY DESIGN

Retrospective clinical study.

METHODS

Records of sinus disease cases presented to The University of Edinburgh Veterinary School between January 2012 and July 2019 were reviewed. Follow-up information was obtained from clinical records and a telephone questionnaire.

RESULTS

Long-term follow up for 155 cases treated sinoscopically showed that 108/155 (69.7%) fully responded to their initial treatment. Concurrent intranasal lesions were identified in 37.4% of cases. Sinusotomy was later required in 10 cases to improve surgical access or sinonasal drainage. Reasons for failure to fully respond to the initial treatment (n = 47) included: intra-sinus bone sequestra (n = 9), inspissated exudate (n = 6) or insects (n = 2); similar material and/or infected conchal bullae in the middle meatus (n = 7); persistent oro-maxillary fistulae (n = 4), misdiagnosed dental apical infections (n = 4); impaired sinonasal drainage (n = 4), progressive ethmoid haematoma regrowth (n = 3) and undiagnosed causes (n = 5). Further treatment of 43 of these cases (67% as outpatients) showed 34/43 cases fully responding to their second treatment. Only 4/155 cases (2.6%) required sinonasal fenestration. In the long term, 149/155 cases (96.1%) showed full and 2/155 cases (1.3%) showed partial improvement. Sinoscopy portal wound infection occurred in nine cases.

MAIN LIMITATIONS

The length of time between treatment and obtaining follow-up information in some cases. Advances in knowledge and techniques over the duration of the study.

CONCLUSIONS

Sinoscopic treatment is a minimally-invasive technique causing minimal morbidity and was successful in 96.1% of cases. Meticulous care should be taken to ensure that bony sequestrae and inspissated exudate are fully removed from the sinuses and nasal cavity during sinoscopic treatments.