EQUINE VETERINARY EDUCATION / AE / MARCH 2015


137


TABLE 1: Number of horses with dental disease and number of affected teeth identified clinically and by each imaging modality


No. horses with dental disease


Clinical Radiography Computed tomography


32 29 32


No. horses with number of teeth involved


1


24 14 19


acquisition data. The same scan area was repeated after i.v. injection of iohexol (Omnipaque)5 (1 ml/kg bwt) in 7 cases. Fistulography was performed in 2 additional cases from Group A and a dacryocystography in another case from Group B. Parameters used for CT scans were 120 kV, 200 mA and 1 s


tube rotation time, or 120 kV, 250 mAand 0.75 s for the first and second scanner, respectively.


Image analysis Image review was performed using DICOM viewing software6. Two observers, one board certified radiologist and one PhD student, simultaneously reviewed the images including radiographs when available, in a randomised order. Interpretation was reached by consensus. Examiners were blinded to the clinical presentation, surgical findings and final diagnosis.


Data evaluation Interpretation based on combined radiographic (in Groups A and B) and CT findings were compared with clinical, surgical and pathological findings, where available. Specific evaluation criteria were used in each group. The


following characteristics were evaluated separately on radiographs and CT in Group A: presence or absence of dental disease including periapical tooth root infection (consisting of disruption of the lamina dura denta, widening of the periodontal space, root resorption and sclerosis of the surrounding alveolar bone) and tooth fractures, side and number of teeth affected. Presence of bony abnormalities, cementomas and draining tracts were also noted. All paranasal sinuses were separately classified as normal, containing fluid lines, or having an overall increase in opacity. When a mass was observed, its shape, size, density and border definition were described. The characteristics described only for CT were presence of gas within the pulp cavity and presence of gas within the infundibulum. The presence or absence of cortical destruction, sclerosis and periosteal proliferation was recorded as dorsal/ventral, palatal/lingual, or buccal in location. Respiratory mucosa was measured at the thickest point in each paranasal sinus and arbitrarily defined as normal when measuring less than 5mm in thickness (Henninger et al. 2003). In Group B, osseous abnormalities including periosteal


reaction, lytic changes, presence or absence of fractures and draining tracts were recorded. Articular abnormalities were recorded separately. Tympanic bulla content, shape and wall thickness changes were also noted. Evaluation criteria in Group C included origin of a mass,


presence or absence of mass effect, mass size, shape, density, attenuation value and border definition. Local tissue invasion, lymphadenopathy and presence of osseous changes were also recorded. Recorded cerebral abnormalities were defined


2 8


14 13


3 0


1 0


Premolars 18


24 21


Affected teeth Molars 22


21 24


Total 40


45 45


as intra- or extra-axial. Lesion type, number (defined as focal or multifocal) and location were recorded according to brain region. The presence of contrast enhancement, brain herniation (transtentorial or foramen magnum) and mass effect (deviation of the falx cerebri from midline or compression of the lateral ventricle) were also recorded.


Statistical analysis Contingency tables were constructed to classify horses from Group A according to their radiography and CT results. For dental disease, estimates of sensitivity (Se), specificity (Sp) and positive and negative predictive values (PPV and NPV) were calculated for each technique using clinical and surgical findings as a gold standard. For sinus involvement, these same estimates were calculated for radiographic findings, using CT results as the gold standard. Confidence intervals were associated to each of the estimates, using 95% as a confidence level. Where calculated values were within the 90–100% range, the exact method was used (Blyth 1986).


Results


A total of 59 horses met the inclusion criteria; 42 in Group A,11 in Group B and6in Group C. Represented breeds were 14 Warmbloods, 14 Thoroughbreds, 12 Quarter Horses, 5 Peruvian Paso, 2 Ponies, 3 Clydesdales, 2 Arabians, 2 Morgan and one each of the following breeds: Andalusian, Appaloosa, Friesian, Haflinger and Lusitan. There were 2 stallions, 31 geldings and 26 mares. The mean age was 11.4 years (range 22 days–25 years).


Dental and sinonasal disease (Group A) This group of 42 horses consisted of 32 dental disease, 6 sinus cysts, one osteoma, 2 progressive ethmoid haematomas and one choanal stenosis. Diagnosis was confirmed surgically in all the horses, except in one horse that was treated conservatively and the osteoma and choanal stenosis that was confirmed post mortem. All horses had a preoperative CT (including all previously mentioned image reconstructions) and radiographs. Three horses also had a repeat CT for recurrent problems. Fistulogram through the draining tract in the facial region was performed in 2 horses. Number of horses with periapical tooth root infection and


number of affected teeth identified by each imaging modality, compared with clinical findings are included in Table 1.


Based on clinical examination and surgical findings, 40


teeth were found to be clinically affected and 33 were treated surgically. In 25 of the 32 horses (78%) radiographs identified at least


one of the clinically affected teeth, while in 7 of the 32 horses (22%) none of the clinically affected teeth were identified. Sensitivity, specificity, positive and negative predictive values for diagnosing dental disease using radiography and CT are


© 2015 EVJ Ltd


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88