DOI: 10.5061/dryad.mpg4f4rb5
title: Diagnostic performance of ultrasonography, bursography and standing magnetic resonance to detect navicular intrabursal pathology in horses with foot pain

description: Navicular intrabursal pathology is one of the most common causes of
 forelimb lameness in horses. An accurate diagnosis of which structure is
 involved is essential for therapy and prognosis. The study aimed
 to compare the diagnostic performance of ultrasonography, bursography, and
 standing magnetic resonance (MRI) imaging as diagnostic tools of the
 proximal navicular intrabursal pathology using bursoscopy as the gold
 standard. A total of 21 feet of 17 horses met the inclusion criteria. The
 feet underwent ultrasonography, followed by MRI, and thereafter
 bursography and bursoscopy. The images were interpreted blindly to
 document the presence or absence of the podotrochlear lesions. The lesions
 of interest were dorsal fibrillation and splits of the deep digital flexor
 tendon (DDFT), adhesions, and fibrocartilage defect of the navicular bone.
 The accuracy, specificity, sensitivity, positive predictive values, and
 negative predictive values were calculated. Furthermore, the kappa test
 was used to calculate the inter-observer agreement. The
 bursoscopy revealed lesions in 95% (20/21) of the feet. Eighteen dorsal
 fibrillation and eleven split lesions in the DDFT, nineteen fibrocartilage
 defects, and eight adhesions were identified. MRI showed accuracy of 95%
 (20/21) for dorsal fibrillation and 86% (9/21) for split lesions in the
 DDFT, whereas the accuracy for fibrocartilage defects was 60% (14/21).
 Adhesion formation with MRI was predicted correctly in only 57% (3/21) of
 the feet. Bursography showed with MRI similar accuracy regarding the
 adhesions. Moreover, bursography had an accuracy for fibrocartilage
 defects of 67% (20/21), and DDFT lesions were detected in 86% (18/21) of
 the feet. The ultrasound examination predicted DDFT lesions in 67% (14/21)
 of the feet, whereas its accuracy for adhesion lesions was 33% (10/21).
 (95% CI). The inter-observer agreement was the lowest for ultrasound
 compared to MRI and bursography. A combination of ultrasonography and
 bursography can be an alternative to standing MRI when the latter is not
 an option or as a complementary test.
description: <strong>2.1. Data collection</strong>
 This prospective blinded study was carried out between 2016 and
 2020 on client-owned adult sport non-racing horses referred with
 unilateral or bilateral forefoot lameness after obtaining the owners’
 approval. The horses were included in the study if the lameness was
 located in the hoof region via diagnostic analgesia, and 2) radiography,
 ultrasonography, and standing MRI of the foot were carried out, 3)
 bursography combined with bursa analgesia was performed within two weeks
 after the previous imaging modalities, and 4) bursoscopy was carried out
 within three weeks after the bursography. The exclusion criteria were
 negative podotrochlear bursa analgesia performed prior to the MRI or
 ultrasound of the foot. The inclusion was decided upon by an associated
 Diplomate of the European College of Veterinary Diagnostic Imaging (KG)
 and a German board-certified veterinary radiologist (MM). The sample size
 was based on convenience sampling, i.e., the number of animals meeting
 inclusion criteria during the study period. The diagnostic work-up was
 performed as part of the patient’s standard clinical evaluation.
 Therefore, no institutional animal care and use approval was
 required. <strong>2.2 Clinical
 examination </strong> The clinical examination
 was performed by an experienced German board-certified equine surgeon
 (GM). All horses were examined clinically on hard and soft surfaces, on
 the straight line, and on circles, either in the clinic facilities or in
 the stable. After gaits were evaluated,  flexion tests and hoof tester
 examination, the palmar digital nerve analgesia was applied just proximal
 to the ungular cartilage using 1 mL of mepivacaine with epinephrine,
 followed by a compression bandage [17]. The analgesia was considered
 positive if the lameness resolved or substantially improved after 5
 min.  <strong>2.3 Radiographic and sonographic
 examination</strong> Standard radiographs,
 including lateromedial, dorsopalmar, and dorso45°proximal-palmarodistal
 radiographs, were acquired after proper foot preparation. Subsequently,
 ultrasound examination of the podotrochlear apparatus was also performed
 on the same day by the same operator (GM) as described previously [9,18].
 Briefly, the palmar area of the pastern was prepared for sonography. The
 images were acquired transversely and longitudinally using a 7.5MHz
 micro-convex transducer (EDGE, Fujifilm Sonosite, Inc., Bothell, WA, USA)
 in a comparable manner with the foot in a non-weight-bearing position. The
 frequency was adjusted to achieve better image quality, and the focus was
 set at the level of the DDFT. The angle contrast ultrasound technique
 (ACUST) [19] was used to increase the conspicuity of the DDFT lobes and
 surrounding soft tissues to enhance evaluation of the dorsal border.
 Moreover, ACUST is the only possible way to image the DDFT in the
 suprasapodeme region due to the hoof configuration and subsequent oblique
 insonation angle. The transcuneal approach was not realised, since only
 the proximal bursa was the area of interest.
 <strong>2.4 Standing MRI material and
 protocol</strong> The foot MRI was acquired with
 a 0.27T MRI scanner (Hallmarq Veterinary Imaging Ltd., Guildford, UK) in a
 standing position under sedation. Images were obtained using gradient
 recall echo, fast spin echo, and short tau inversion recovery (STIR)
 sequences in sagittal, transverse, and dorsal planes (Table 1). The
 transverse images were angled perpendicular to the DDFT in the supra- and
 infrasesamoidean region. In addition to the standard basic protocol, an
 additional transverse proton density and high-resolution T2 FSE sequences
 were acquired, depending on the findings observed at the time of the
 acquisition by the radiologist performing the examination. 
 <strong>2.5 Bursography</strong>
 The bursography was performed simultaneously with intrathecal
 diagnostic analgesia using the lateral approach as described previously
 [20]. Briefly, a 3 mL mixture of 1:1 positive contrast agent and local
 anaesthetic (1.5 mL mepivacaine, Intra-Epicaine 20mg/mL, Dechra Veterinary
 Products Deutschland GmbH, Aulendorf, Germany, and 1.5 mL Solutrast, 250
 mgI/mL Iopamedol, Bracco Imaging Deutschland GmbH, Konstanz, Germany) was
 injected intrathecally under aseptic conditions. Immediately after the
 intrathecal injection, lateromedial and palmaro-45°-proximal-palmarodistal
 oblique radiographs of the navicular region were acquired. After 5 min,
 the results of the analgesia were evaluated and considered positive if a
 significant improvement in or abolishment of the lameness was
 observed. <strong>2.6
 Bursoscopy</strong>  All surgeries were performed
 by the same operator (GM) using a standard transthecal approach [15], and
 treatments were administered as needed. Briefly, after positioning the
 animal in dorsal recumbency and after routine surgical preparation, the
 arthroscopic and instrumental portals were created just proximal to the
 ungular cartilage. The T-ligament was sharply dissected, and the bursa was
 inspected. Using motorized blades, arthroscopic scissors, and an
 arthroscopic punch, the lesions were debrided. During the surgical
 debridement, the arthroscopic and instrumental portals were often
 exchanged. Eventually, after copiously flushing, the portals were closed,
 and a sterile bandage was applied.  <strong>2.7
 Image analysis</strong> Diagnostic and surgical
 findings were reviewed by independent, experienced observers who were
 blinded to the history, clinical examination, or tentative diagnosis of
 these horses. The ultrasound, bursography, and MRI images were anonymized
 in DICOM format to enable the operator to adjust the contrast windows
 level and width as required. The bursoscopy images and clips were provided
 in JPEG and MP4 format, respectively.  The bursography
 was assessed by a board-certified European College of Veterinary
 Diagnostic Imaging radiologist (ZJ). The MRI and ultrasound findings were
 interpreted by an American College of Veterinary Radiology-certified
 radiologist (NW). Since the same operator had to evaluate the modalities
 of the same patient, the ultrasonography images were evaluated six months
 after the MRI to avoid possible bias. The bursoscopy images and videos
 were assessed by a member of the board of the European College of
 Veterinary Surgeons (BB).   To assess interobserver
 agreement of all three diagnostic modalities, the interpretation of all
 findings was performed independently and blinded by an experienced
 radiologist (MM, German board-certified veterinary radiologist) and one
 board-certified radiologist (NW, ZJ). The assessment protocols were
 collected and adapted from literature [6,7,10,11,13] by the first author
 and approved by the observers. The proximal navicular bursa was reviewed
 for the following lesions: 1) fibrocartilage defects of the proximal
 aspect of the navicular bone flexor surface (bursography, MRI), 2)
 adhesions/synovial masses (ultrasound, bursography, MRI), 3) split of DDFT
 (ultrasound, bursography, MRI), and 4) dorsal border lesion/tendinopathy
 of DDFT (ultrasound, bursography, MRI). In case of DDFT tendinopathy and
 fibrocartilage defects, the location was also reviewed (lateral/medial).
 The lesions were reported as present or absent, grading the severity
 according to the worst lesion in that both lobes were affected, and their
 position (medial vs lateral vs both). Lesions not evaluated with
 bursoscopy were purposely excluded from the study. The
 fibrocartilage was defined as normal if it appeared as a uniform
 radiolucent area 1 to 2 mm in thickness covering the flexor surface of the
 navicular bone in bursography. In MRI, the fibrocartilage was considered
 abnormal if irregularity of the flexor surface was evident without a
 compact defect associated with subjective thinning and change in signal of
 the palmar fibrocartilage.  Adhesion was defined in
 bursography as focal interruption of the contrast column between the
 navicular bone and the dorsal margins of the DDFT. It was the authors’
 decision to use the term adhesion as a synonym for both synovial masses
 and adhesions [21].  An adhesion was diagnosed in MRI and ultrasound when
 there was a discontinuity in the navicular bursa fluid between two
 structures lining the proximal pouches, with or without extraneous tissue
 present.  During the surgery, adhesions were identified as an abnormal
 band of tissue connecting two structures.  A split of
 the DDFT was diagnosed in bursography if there was a linear accumulation
 of contrast agent inside the dorsal area of the DDFT lobe. In MRI, the
 split was defined as narrow linear areas of increased signal intensity on
 T1 sequences at the suprasesamoidean portion of DDFT. In ultrasound, the
 DDFT lesion was defined as a heterogeneous hypoechogenic line extending
 through the DDFT lobe.  A dorsal fibrillation of the
 DDFT was defined in bursography as loss of the smooth margin of the palmar
 surface of the bursa. In MRI, this lesion was characterised as
 irregularity of the dorsal margin of the DDF tendon visible on T1, PD, T2,
 and STIR FSE sequence, whereas in ultrasound examination, it was defined
 as interruption of the dorsal margin of the DDFT with or without
 isoechogenic structures originating from DDFT and protruding into the
 navicular bursa.   <strong>2.8. Statistical
 assessment   </strong> Statistical analyses were
 performed by the first author in collaboration with an external medical
 statistician using SPSS V.23 (SPSS Software, IBM Munich Center GmbH,
 Munich, Germany). The statistical analyses included calculating the
 sensitivity, specificity, and accuracy, and the positive and negative
 predictive values for each modality using bursoscopy as the gold standard
 with a 95% confidence interval. Weighted kappa values for each lesion’s
 grade with 95% confidence intervals were calculated to assess
 inter-observer agreement in MRI, bursography, and ultrasound as follows:
 Kappa &lt;0  as “no agreement”; Kappa = 0.0 to 0.20 as “poor
 agreement”; Kappa = 0.21 to 0.40 as “fair agreement”; Kappa = 0.41 to 0.60
 as “moderate agreement”; Kappa = 0.61 to 0.80 as “substantial agreement”;
 Kappa = 0.81 to 1.00 as “almost perfect agreement” [22]. The prevalence
 rate of each lesion was used as reported previously [7].
description: # Diagnostic performance of ultrasonography, bursography and standing
 magnetic resonance to detect navicular intrabursal pathology in horses
 with foot pain
 [https://doi.org/10.5061/dryad.mpg4f4rb5](https://doi.org/10.5061/dryad.mpg4f4rb5) ## Description of the data and file structure ### Files and variables #### File: Outcome\_and\_shoes\_of\_the\_patients.xlsx 10.32 KB **Description:** Signalment of the population of this study: 1. horse (registration number of patient ) 2. gender (stallion, mare, gelding) 3. birth year (when the horse was born) 4. breed (warmblood, paint horse) 5. limb (Right, Left) 6. discipline (dressage, Jumping, eventing) 7. outcome (sound, lame) 8. laser intra-OP (Y/N) 9. Shoes (egg-bar, wedge 5°) 10. age (age in years of the patient on OP-day)   #### File: Bursography\_ZJ.xlsx 10.01 KB **Description:** blind assessment of the bursography from Zoe Joostens. **In the first sheet** ID = registration number of the patient 1. Fibrocartilage: Defect in the fibrocartilage surface of the navicular bone. (N= no, M=mild, Mo= moderate, S= severe) 2. DDFT fibrillation = defect in the dorsal surface of the deep digital flexor tendon in the proximal area of the navicular bursa. Measurements same as above. 3. DDFT split LAT = Split lesion beginning from the dorsal surface of the DDFT in the lateral proximal area of the navicular bursa. Same measurements as above. 4. DDFT split MED = Split lesion beginning from the dorsal surface of the DDFT in the med proximal area of the navicular bursa. Same measurements as above. 5. Bursitis = Inflammation of the navicular bursa (change of the bursa shape in the contrast radiography). Measurements same as above. 6. Adhesions =  Fibrous structures inside the proximal area of the navicular bursa. Y=yes, N=no. **In the second sheet:** same values as in sheet 1, but assessment with Y/N. #### File: Bursography\_MM.xlsx 9.33 KB **Description:** blind assessment of the bursography from Mahmoud Mageed. ID = registration number of the patient. Fibrocartilage defect, adhesions, DDFT fibrillation, and DDFT splits were evaluated with Y/N.  #### File: Bursography\_GM\_unblind.xlsx 9.33 KB **Description:** Unblind assessment of the bursography from Grigorios Maleas. ID = registration number of the patient. Fibrocartilage defect, adhesions, DDFT fibrillation, and DDFT splits were evaluated with Y/N. #### File: Criteria\_für\_Observations.docx **Description:** criteria for the observers in these variables: 1) fibrocartilage defect, 2) adhesions, 3) DDFT fibrillation, and 4) DDFT splits. Observation in the following diagnostic modalities: MRI, ultrasound, contrast radiography, and bursoscopy.  #### File: MRI\_Natasha\_Werpy\_and\_MM.xlsx **Description:** MRI description for the patients from two blind observers. Sheet 1 = NW, Natasha_Werpy. Sheet 2 = MM, Mahmoud Mageed. For both sheets. Fibrocartilage defect, adhesions, DDFT fibrillation, and DDFT splits were evaluated with Y/N.  #### File: Bursoscopy\_Bruce\_and\_GM.xlsx **Description:** blind and unblinded evaluation of the bursoscopy. Sheet 1 = BB, Bruce Bladon (blind observer) Sheet 2 = GM, Grigorios Maleas (unblind observer) For both sheets: Fibrocartilage defect, adhesions, DDFT fibrillation, and DDFT splits were evaluated with Y/N.  #### File: Ultrasound\_NW\.xlsx 9.5 KB **Description:** blind assessment of the ultrasound images from Natasha Werpy.   DDFT fibrillations, bursitis, DDFT splits, and adhesions were evaluated with Y/N. #### File: Ultrasound\_MM.xlsx 9.14 KB **Description:** blind assessment of the ultrasound images from Mahmoud Mageed. DDFT fibrillations, bursitis, DDFT splits, and adhesions were evaluated with Y/N. #### File: Ultrasound\_GM.xlsx 9.32 KB **Description:** Unblind assessment of the ultrasound images. DDFT fibrillations, bursitis, DDFT splits, and adhesions were evaluated with Y/N. #### File: Diagnostic value bursoscopy\_US.xlx 11.57 KB **Description**: Statistical analyses between buscoscopy and ultrasound were performed by the first author in collaboration with an external medical statistician using SPSS V.23 (SPSS Software, IBM Munich Center GmbH, Munich, Germany). Sheet 1: comparison - end- results. DDFT fibrillations, DDFT splits, and adhesions were evaluated with Y/N in all patients (ID = number of registration). Sheet 2: Statistic: True/false, yes and no from ultrasound. The statistical analyses included calculating the sensitivity, specificity, and accuracy, and the positive and negative predictive values for ultrasound using bursoscopy as the gold standard with a 95% confidence interval (95% CI). ### File: Diagnostic value bursoscopy\_Rad.xlx 10.86 KB **Description**: Statistical analyses between buscoscopy and bursography (contrast-radiography) were performed by the first author in collaboration with an external medical statistician using SPSS V.23 (SPSS Software, IBM Munich Center GmbH, Munich, Germany). Sheet 1 Y_N = true and false, yes and no of bursography. Sheet 2 statistic: The statistical analyses included calculating the sensitivity, specificity, and accuracy, and the positive and negative predictive values for bursography using bursoscopy as the gold standard with a 95% confidence interval (95% CI). ### File: Diagnostic value bursoscopy\_MRI.xlx 12.13 KB **Description**: Statistical analyses between bursoscopy and MRI.  Sheet 1: Comparison - end results. DDFT fibrillations, DDFT splits, adhesions, and fibrocartilage values were evaluated with Y/N. Sheet 2:  Statistic: True/false, yes and no from ultrasound. The statistical analyses included calculating the sensitivity, specificity, and accuracy, and the positive and negative predictive values for MRI using bursoscopy as the gold standard with a 95% confidence interval (95% CI). Weighted kappa values for each lesion’s grade with 95% confidence intervals were calculated to assess inter-observer agreement in MRI, bursography, and ultrasound as follows: Kappa &lt;0  as “no agreement”; Kappa = 0.0 to 0.20 as “poor agreement”; Kappa = 0.21 to 0.40 as “fair agreement”; Kappa = 0.41 to 0.60 as “moderate agreement”; Kappa = 0.61 to 0.80 as “substantial agreement”; Kappa = 0.81 to 1.00 as “almost perfect agreement”. #### File: Population.zip **Description:** images of the patients/population of the study. There are 17 horses and 21 feet. Registration number of each horse, with L = left foot, and with R = right foot. Example images or videos of the lesions with contrast radiography, ultrasound, MRI, and surgery are included in each case. Videos' description 15_Patient_212641: Video Bursoscopy 1 (prior debridement from fibrillations) Video Bursoscopy 2 (post debridement of fibrillations of DDFT). 17_Patient 135505: Video Bursoscopy: Adhesions in the navicular bursa and debridement. 18_Patient 188986: Video Bursoscopy: Adhesions/Synovial mass and resection. Fibrocartilage defects in the navicular bone. 19_Patient_168778: Video Bursoscopy: adhesion and resection with shaver. #### **File: [kappa\_tests\_summury\_MRI\_US\_Rads.xlsx](https://datadryad.org/downloads/pre_submit/4041387 "Download from Dryad")** **Description:** Weighted kappa values for each lesion’s grade with 95% confidence intervals were calculated to assess inter-observer agreement in MRI, (Rad) bursography, and ultrasound (US) as follows: Kappa &lt;0  as “no agreement”; Kappa = 0.0 to 0.20 as “poor agreement”; Kappa = 0.21 to 0.40 as “fair agreement”; Kappa = 0.41 to 0.60 as “moderate agreement”; Kappa = 0.61 to 0.80 as “substantial agreement”; Kappa = 0.81 to 1.00 as “almost perfect agreement”. ## Access information Other publicly accessible locations of the data Data was derived from the following sources: * Tierklinik in Luesche GmbH * Grigorios Maleas, Equuria GbR