Continuous rate infusion of dexmedetomidine vs subcutaneous administration in anaesthetized horses undergoing MRI examination

Up to 2005, dexmedetomidine use had not been reported in equine. Since then, several experimental and clinical studies have been published. The main reason for this increase relies on its beneficial pharmacological profile, including short half-life and rapid redistribution (1). The aim of the study is to compare the clinical effects and recovery quality after continuous rate infusion (CRI) or subcutaneous administration of dexmedetomidine in horses undergoing general anaesthesia. Fourteen horses scheduled for MRI examination were included. All horses were sedated with acepromazine 0.03 mg kg-1 intravenously (IV) and detomidine 10 \ub5g kg-1 (IV). Anaesthesia was induced with ketamine 3 mg kg-1 (IV) and diazepam 0.04 mg kg-1 (IV) and maintained with isofluorane in 60% oxygen; end-tidal isoflurane concentration was maintained between 1.3-1.4 %. Horses were randomly divided in two groups. Group \u201cDex CRI\u201d received dexmedetomidine intravenously at 1 \ub5g kg-1 hour-1, group \u201cDex SC\u201d received 2 \ub5g kg-1 of dexmedetomidine subcutaneously every 60 minutes. If nystagmus or incessant fighting against ventilator occurred, ketamine rescue at 0.1 mg kg-1 was given. In case of sudden movements, thiopental 0.5-1.0 mg kg-1 IV was given. Ringer\u2019s lactate was given at 3 mL kg-1 hour-1, dobutamine was administered IV and the rate adjusted to maintain MAP>70 mmHg. Controlled mechanical ventilation using intermittent positive pressure ventilation was adjusted to maintain arterial carbon dioxide partial pressure between 38-45 mmHg. Heart rate, invasive arterial blood pressure, arterial blood gases, total dose of dobutamine administered, ketamine rescue needed, urine production were recorded. Time required until extubation and time to attain sternal and standing position were noted. The main anaesthesiologist assessed recovery quality graded on a standard scoring 5-point scale with a score of 1 representing the best recovery (2). Mann-Whitney U test was applied for non-parametric data and T-test for parametric data (p 640.05). There was no statistically differences in physiological intra-anaesthetic parameters, in body weight (kg) (CRI 521\ub153; SC 506\ub176), age (years) (CRI 10.7\ub12.1; SC 10.8\ub14.1), anaesthesia duration (min) (CRI 139\ub19.,7; SC 144\ub116.2), number of ketamine rescue needed (CRI 1\ub11.15; SC 0.5\ub11.13), recovery score (CRI 1.8\ub11,2; SC 1.5\ub10,5). Also time until extubation (min) (CRI 11.5\ub15.0; SC 9.7\ub12.6), time to attain sternal (min) (CRI 41.5\ub112.2; SC 49.7\ub16.0) and standing position (min) (CRI 50.7\ub114.6; SC 57.2\ub16.,0) were not statistically different. There was statistical significance in urine production (L) (CRI 8.0\ub13.5; SC 11.1\ub14.4) and total dobutamine mcg/kg/min (CRI 0.89\ub10.35; SC 0.56\ub10.18). Subcutaneous administration of dexmedetomidine has product similar clinical effects to those achieved with CRI. It has permitted a significative reduction in dobutamine administration and a more stable depth of anaesthesia confirmed by the lower number of rescue ketamine boluses required even if not statistically different. Further studies are required to evaluate different dosages both in CRI and subcutaneous administration

Peribulbar block in equine isolated heads : development of a single needle technique and tomographic evaluation

Peribulbar block (PPB) has been used in humans as a safer alternative to retrobulbar block (RBB). PBB, depends on the diffusion of anaesthetic solution into the muscle across the connective tissue and it is performed introducing the needle within the extraconal space. The advantages are fewer complications and palpebral akinesia. In Veterinary Medicine few studies describe this technique in dogs and cats (Shilo- Benjamini et al., 2013). The aim of the study is to determinate, in equine specimens, feasibility of inferior PBB with single needle injection, by using contrast medium (CM), and to evaluate thought Computed Tomography (CT) the distribution of the injected volume and regional anaesthesia likelihood. PBB was performed in 10 orbits. The mixture injected consisted of 20 ml of physiological solution and iodinated CM at 25%. Each periorbital area underwent three CT scans. A basal acquisition to assess the needle position before the injection, a second and third scan were performed immediately after injection, and after application of pressure on the periorbital surface area to promote CM diffusion. The injectate distribution at the base and within the extraocular muscle cone (EOMC) and around the optic nerve was evaluated and scored based on Shilo-Benjamini\u2019s work of 2017. The mean minimum distance between the tip of the needle and the optic was 2,23 mm \ub10,2. The mean volume distribution before pressure application was 23.56 cm3 \ub1 2.58 and after pressure application was 27.56 cm3 \ub1 4.8. The CM median distribution around the optic nerve at the base of the EOMC was of 117\ub0 prior pressure and 189\ub0 after pressure. The CM distribution within the EOMC was present in 1 orbit prior pressure and in 3 orbits after pressure. The CM distribution at the base of EOMC was considered unlikely to provide regional anaesthesia in 2 orbits, possible in 3 orbits and likely in 5. In the present study, intraconal distribution was not consistent. For this reason, the likelihood of achieving regional anaesthesia was evaluated at the EOMC base where through the optic foramen the oculomotor, trochlear nerve, ophthalmic branch of the trigeminal nerve, and the abducens travel to reach the orbit together with the optic nerve. Whereas the maxillary branch of the trigeminal nerve passes through the foramen rotundum (Carastro 2004). Therefore, despite the lack of intraconal distribution if the EOMC base had good distribution then it was considered likely to provide regional anaesthesia. This approach needs to be evaluated in clinical trials to assess its feasibility and effectiveness in locoregional anaesthesia; moreover, further investigations on equine PBB are mandatory with higher volumes of injectate and different approaches

Comparazione del constrast enhancement in esami ortopedici ad RM del paziente equino tramite bassi volumi di mezzo di contrasto inoculati per via arteriosa distrettuale e giugulare

Scopo del lavoro. La Risonanza Magnetica (RM) riveste ad oggi un importante ruolo nella dia- gnostica ortopedica equina, permettendo di identificare in modo efficace sia alterazioni a carico dei tessuti mineralizzati che dei tessuti molli. Non sempre per\uf2 tali alterazioni hanno una rilevanza di tipo clinico. Infatti, lesioni croniche caratterizzate dalla presenza di tessuto cicatriziale rimangono visibili anche quando non pi\uf9 responsabili della zoppia dei soggetti esaminati. Inoltre, la presenza di lesioni subdole pu\uf2 non essere riconosciuta attraverso un esame che preveda un protocollo standard. Per ovviare a questi problemi, in medicina umana si \ue8 ormai diffuso l\u2019impiego di mezzo di contra- sto (m.d.c.) somministrato per via endovenosa (i.v.). Il m.d.c. consente di discriminare tra lesioni at- tive e in via di guarigione ed identificare lesioni altrimenti poco evidenti. Per quanto attiene il paziente equino a conoscenza degli autori in letteratura esistono solo due stu- di che descrivano l\u2019utilizzo di m.d.c. in RM nella diagnosi di patologie tenodesmiche1,2 e ne preve- dono la somministrazione per via i.v. Nel lavoro proposto da Puchalski et al. (2007), invece, il m.d.c. viene somministrato per via endo-arteriosa (i.a.) ma l\u2019esame \ue8 stato condotto per mezzo di un tomografia computerizzata a raggi x. Lo scopo del presente studio \ue8 quello di descrivere e confrontare l\u2019utilizzo di m.d.c. sia per via i.v. che per via i.a. in RM, in cavalli affetti da zoppia localizzata alla regione del piede. Materiali e metodi. Nello studio sono stati inclusi cavalli con zoppia localizzata al piede e sotto- posti ad esame RM in cui sia stato somministrato m.d.c. per via i.v. o i.a. Sono state acquisite sequenze T3DT1, Dual Echo, STIR nei differenti piani di scansione. \uc8 stato poi somministrato m.d.c. (Gadodiamide) per via i.v. al dosaggio di 0,1 ml/kg attraverso la v.giugulare destra oppure per via i.a. ad un dosaggio di 0,02 ml/kg attraverso la a.arteria radiale o in quella me- tatarsale. Sono quindi state acquisite sequenze T3DT1 in post-contrasto. Per mezzo di un software dedicato, nelle immagini acquisite in pre e post-contrasto \ue8 stata misura- ta l\u2019intensit\ue0 di segnale dei pixel di regioni di interesse (ROI) in punti prestabiliti (in assenza di al- terazioni patologiche) e nelle aree in cui sono state osservate alterazioni a carico delle strutture te- nodesmiche. Per poter valutare il grado di presa di contrasto, sono state calcolate le ratio tra il valore della ROI pre e post-contrasto. Risultati. Nello studio sono stati inclusi 6 soggetti; in 2 cavalli il m.d.c. \ue8 stato somministrato per via i.v., in 3 soggetti per via i.a. attraverso l\u2019arteria radiale e in 1 per via i.a. attraverso l\u2019arteria me- tatarsale. In tutti i soggetti, il valore maggiore della ratio \ue8 stato osservato a livello di a. digitale palmare me- diale, di articolazione interfalangea distale, di corticale dorsale di P2. Le strutture che hanno dimo- strato un maggior contrast enhancement in presenza di patologia sono state il tendine flessore pro- fondo del dito (DDFT), la spongiosa del navicolare ed i tessuti peritendinei. In assenza di patolo- gia, il DDFT non ha mostrato incremento significativo di segnale dopo somministrazione di m.d.c. Conclusioni. Come descritto da Judy et al. (2010) Le sequenze acquisite in post-contrasto hanno permesso di riconoscere non solo lesioni gi\ue0 visibili in assenza di m.d.c. e di verificare quali tra que- ste fossero responsabili della sintomatologia in atto, ma hanno anche consentito di mettere in evi- denza alterazioni altrimenti non riconoscibili, soprattutto a carico di tessuti peritendinei e legamen- to impari distale. In 4 soggetti \ue8 stato riscontrato tessuto cicatriziale che, successivamente all\u2019inoculazione di m.d.c. \ue8 stato classificato come \u201creattivo\u201d. L\u2019elevato valore della ratio della corticale dorsale di P2 osser- vato nel presente lavoro ed in contrasto con quanto descritto in letteratura1, \ue8 verosimilmente da ri- tenersi riconducibile ad un artefatto da volume parziale. Nel presente studio \ue8 stato verificato come anche in RM sia possibile l\u2019impiego di m.d.c. per via sia i.v. che i.a. I vantaggi derivanti dalla som- ministrazione per via i.a. derivano dal minor dosaggio di m.d.c. richiesto, che consente di contene- re i costi e di ridurre i possibili effetti collaterali legati al farmaco soprattutto in pazienti anziani o affetti da patologie renali ed epatiche. Inoltre, nei cavalli in cui il m.d.c. \ue8 stato somministrato per via i.v. i valori delle ratio nei punti prestabiliti (e quindi confrontabili) sono stati inferiori rispetto a quelli ottenuti in cavalli in cui era stata effettuata l\u2019inoculazione i.a. Ulteriori studi sono tuttavia ne- cessari per verificare quale tra le due metodiche di somminitrazione garantisca un migliore contrast enhancement e se la somministrazione i.a. possa essere utilizzata anche in \u201cstanding RM\u201d. Concludendo, seppure siano esigui gli studi a riguardo, si pu\uf2 affermare che l\u2019utilizzo di m.d.c. per via sia i.v. che i.a. nell\u2019indagine RM di patologie ortopediche nel cavallo, sia da ritenersi molto uti- le, soprattutto per l\u2019identificazione e la classificazione di patologie tenodesmiche

Diagnostic value of whole body bone scan in horses

Scintigraphy is widely used in the assessment of musculoskeletal disorders and often it is considered as a screening tool in lame or poor performing horses. It is proved that nuclear scintigraphy is useful in highlighting the presence of lesions undetectable by clinical examination, in horses that do not respond to local analgesic blocks or with intermittent lameness[1]. Despite the usefulness of bone scan is proven, in a recent report, Quiney et al. observed that false-negative results predominate and may lead to missed diagnosis[2]. The aim of this study is to analyze the diagnostic usefulness of whole body bone scan in horses referred for lameness or poor performance. For this retrospective study, bone scans acquired at the Ospedale Veterinario Universitario di Lodi between July 2014 and February 2019 were reviewed. In the study have been included only horses that had a whole body bone scan. On the basis of the history, horses were classified as poor performing, for localized lameness or non-localized lameness. Scintigraphic findings were organized in five categories: definitive diagnosis, localization of the lameness, no findings related to the present clinical signs, findings of unlikely clinical significance and findings that need further investigations. A contingency table and a chi-squared test were used for the statistical analysis. One hundred and eighty horses underwent scintigraphy and 102 were included in the study; twenty-one horses were referred for lameness localized using diagnostic analgesia while in 44 horses the source of lameness was not identified. Thirty-seven horses had an history of poor performance. Statistical analysis highlighted that the only correlation between clinical history and scintigraphic findings was between horse referred for poor performance and findings of unlikely clinical significance (59,5% of horses with a poor performance diagnosis). A final diagnosis or localization of the source of pain were observed respectively in the 5.9% and in the 29.4% of horses. In 11 subjects (10.8%) were found increased radiopharmaceutical uptakes (IRU) of uncertain clinical significant that needed further investigations using analgesic blocks. In the 20% of cases, all referred for lameness, no findings related to the present clinical signs were found. In order to increase the capability of bone scintigraphy, it is mandatory to consider that the sensitivity and specificity are higher in specific regions[2] and the interpretation of the relevance of IRU must be based on detailed clinical examination. In conclusion, we confirm that whole body bone scintigraphy should not be considered a diagnostic screening especially in poor performing horses and that localization of lameness can improve the possibility of a positive result. [1] Dyson S.J. Musculoskeletal scintigraphy of the equine athlete. Semin Nucl Med, 44:4-14, 2014. [2] Quiney L., Ireland J., Dyson S.J. Evaluation of the diagnostic accuracy of skeletal scintigraphy in lame and poorly performing sports horses. Vet Radiol Ultrasound, 59:477-489, 2018

Brain imaging in rabbits : preliminary results of CBF variation by different anaestethic drugs

In the last decades the animal model has been usually considered as a research tool, especially for functional studies and brain imaging. Although general anesthesia and sedation are fundamental requirements to perform nuclear imaging in veterinary patients, very few studies have been published on the effect of anesthesia itself, on brain perfusion. Brain SPECT in humans is widely applied to assess brain perfusion mainly in awake patients. The aim of the study was to evaluate general brain perfusion in rabbits through a non-invasive nuclear medicine technique, before and after the administration of different anesthetic protocols commonly used for veterinary patients. Ten male New Zeland White rabbits of 6 months of age were enrolled in the prospective study. Before SPECT examinations, the rabbits underwent CT studies of the skull in order to exclude any gross malformations or lesions and to acquire images for CT/SPECT fusion. 99mTc-HMPAO brain SPECT scans were acquired with a single head gamma camera: circular orbit, continuos rotation 10 seconds/step and 120 steps. During the first session 99mTc-HMPAO was IV injected in two groups of five awake rabbits, with a randomized selection. The first one was subsequently anesthetized with propofol and the other with dexmedetomidine. The same procedure was repeated three weeks later when the injection of the radiopharmaceutical was performed after the induction of general anaesthesia. The brain perfusion uptake index (BPUi%) was calculated as the percentage ratio between total counts in the brain and injected activity. Rabbits anesthetized with propofol showed exactly the same tracer distribution in both injection condition: awake or asleep. The radiopharmaceutical was concentrated in the brain but a generalized distribution was observed also in the facial muscles. On the contrary when dexmedetomidine was used, rabbits anesthetized after the 99mTc-HMPAO injection showed a distribution similar to propofol group, while when the radiotracer was injected after the anesthetic drug, a generalized reduction of the uptake was observed especially in extra-encephalic tissues. The average BPUi% values were about 1.6% for all rabbits anesthetized with propofol and for rabbits injected with 99mTc-HMPAO before dexmedetomidine administration. Animals injected with 99mTc- HMPAO after dexmedetomidine administration showed a lower value of BPUi% equal to about 1.25 %. Although the major limitation of our study is the small number of subjects analyzed, our results showed that when propofol is used as anesthetic drug, any difference in brain perfusion occurred if the radiotracer was injected prior or before anesthesia. On the contrary the vasocostriction of dexmedetomidine is responsible of a mild reduction of the IRU in the brain and a good inhibition of tracer uptake in other tissues. These preliminary data suggest that the use of propofol in uncooperative patients, that need sedation before brain perfusion studies, could not influence the CBF. On the other hand the results of the CBF in rabbits medicated with dexmedetomidine before tracer injection, suggest a possible neuronal protective proprieties of this drug

Spleen hematoma in a ferret: imaging and surgical findings

Spleen hematoma is not an uncommon pathology in the ferret, nevertheless it has been poorly described in literature. A 5,5 years old male neutered ferret was referred for anorexia and gastrointestinal disorders. Physical examination revealed a no painful moderate abdominal distension. Radiographic examination of the abdomen revealed a mass of 20mm in diameter in the spleen. A complete blood analysis was carried out and revealed a mild leukocytosis. The mass was further investigated by ultrasonography (US) that confirmed the presence of an hypoechoic rounded lesion within the splenic parenchyma. Differential diagnoses included spleen hematomas, coronavirus infection, lymphoma or lymphosarcoma. The size and morphology of the mass and the blood values has been monitored frequently by ultrasound and no fine needle aspiration was performed in order to avoid bleeding. To better characterize the lesion a multidetector Computed Tomography (CT) pre and post-contrast examination of the chest and abdomen was performed and revealed a huge intraparenchymal hypoattenuating mass in the apex of the spleen (35 mm in diameter), showing a mild enhancement on post-contrast sequences. Because of US and CT finding was suggestive of a benign infiltrative pathology, a splenectomy was recommended. Five days later the patient was admitted to surgery in emergency because the mass was lacerated spontaneously. The histologic examination of the mass confirmed a spleen hematoma. Spleen hematoma should be considered as a differential diagnosis in case of or nodular lesions or splenomegaly in the ferret

Injuries at the articular surface of the proximal phalanx and third metacarpal/metatarsal bone in horses, detected with low-field magnetic resonance imaging: 13 case (2010-2017)

Introduction Injuries to the fetlock region are common in horses used for athletic purposes and Magnetic Resonance Imaging (MRI) is diffusely used to diagnose bone injuries (1-3). Despite the classification used in human medicine (4), in the equine practice the terms \u201cshort incomplete fracture\u201d, \u201cstress fractures\u201d, \u201cfissure, transchondral fracture\u201d and \u201costeochondral fracture\u201d are often used interchangeably. The purpose of the study was to report the case details, diagnostic imaging findings and outcomes in sport horses with a diagnosis of traumatic injuries at the articular surfaces of metacarpophalangeal and metatarsophalangeal joint (MCPJ/MTPJ) and verify if it is possibile to differentiate between subchondral, chondral and osteochondral fracture using a low-field MRI under general anesthesia. Material and methods Magnetic Resonance examination of horses referred for lameness localised to the fetlock region over a 7-year period were reviewed. Horses were selected for inclusion in the study that had MRI findings suggestive of primary bone lesion involving the articular surface of third metacarpal/metatarsal bone (MCIII/MTIII) or proximal phalanx (P1). Signalment, detailed clinical history, athletic use, MRI findings and follow-up informations were recorded. On the basis of MRI patterns, injuries at the articular surface were classified as osteochondral fractures (OF), chondral fractures (CF), or subchondral fractures (SF) (4). Lesions were identified as an OF when defect of cartilaginous lining and/or signal change of the cartilage layer was observed in association with subchondral bone marrow lesion and arcuate or linear irregular signal change in the subchondral bone. In the SF there was no involvement of the cartilaginous lining, while in the CF there is a displaced fragment and no alteration of the subchondral black line. Results Thirteen horses have been included in the study; five horses were used for show jumping, four for flat race, two for monta vaquera and two for eventing and dressage, respectively. The median age was 8.5 years of age, with a range between 2 and 16 yo. All horses had unilateral lameness, seven horses with acute onset, while six had a chronic lameness (>12 weeks). The degree of lameness varied from grades 2/5 to 4/5. In four horses lameness was localised to the hindlimb. In four horses a subtle, radiolucent, ill-defined line was observed in the radiographic views, suggestive of short incomplete fracture. Six horses had MRI findings suggestive of OF (impacted type) involving the sagittal groove of P1 in three cases, the medial aspect of P1 in one horse and the medial condyle of MCIII/MTIII in two horses. Seven horses had SF at the medial condyle of MCIII/MTIII in three cases, at the lateral condyle of MCIII/MTIII in two cases and involving the sagittal goove of the proximal phalanx in the last two cases. No MRI findings suggestive of CF were observed in the present study. In six horses no other abnormalities were detected while in seven cases additional alterations were observed, including mild desmopathy of MCPJ/MTPJ collateral ligaments, desmopathy of the suspensory ligament branches, oblique sesamoidean ligament alteration or adhesions between deep digital flexor tendon and distal sesamoidean impar ligament. All horses were treated with a period of rest; four horses received a therapy with biphosphonates and one horse was treated with intra-articular jaluronic acid. Median time of the final follow up was 32 weeks (range: 12 to 40 weeks). Of the 13 horses included in the study, nine (69%) were sound and returned to thier previous athletic use. Three horses were still lame due to MCPJ/MTPJ pain while another one was lame due to pain localised to the suspensory ligament origin. Conclusion In equine practice, the terms osteochondral fractures, tranchondral fractures, short fracture and incomplete fracture were used interchangeably. Differentiating between osteochondral and subchondral fractures is mandatory for an accurate prognosis (4). Even if low-field MRI has a low sensitivity in detecting articular surface damage (3,5), in the present study was possible to discriminate between OF and SF in all cases. Fat-suppressed images had the capability to enhance occult bone lesions like bone marrow traumatic damage. Fat-suppressed and T1-Weighted sequences allowed to detect defect in the overlying articular surface. Despite the results reported by Gold et al. (2017) in the present study 70% of cases returned to previous athletic levels (1). Considering that all horses with a diagnosis of subchondral fracture were sound at the time of re-check while horses still lame had osteochondral fracture, we can speculate that subchondral fracture has a better prognosis. In our study all horses underwent a period of rest and none received a surgical management. Differentiating between SF and OF could help the surgeon in the treatment choice, conservative in case of subchondral injuries and surgical when cartilage involvement was detected (6,8). In the report of Smith at all. (2017), of 12 cases with a diagnosis of short incomplete fracture or osteochondral fracture, 11 returned to race after surgical repair. Even if radiographic examination can, in some cases, identify short incomplete fractures, magnetic resonance examination allows to evaluate the presence of cartilage involvement, bone marrow lesions and simultaneous soft tissue abnormalities (6). The early diagnosis of these lesions is mandatory to prevent repetiteve loading on damaged bone and possible extension to the cortex (7) that can led to catastrophic injuries In conclusion, MRI has to be considered the best imaging technique in the evaluation of an incomplete fractures, in order to differentiate between osteochondral and subchondral fractures for the elective treatment of a specific pathological entity

Injuries at the articular surface of the proximal phalanx and third metacarpal/metatarsal bone in horses, detected with low-field magnetic resonance imaging: 13 case (2010-2017)

Introduction Injuries to the fetlock region are common in horses used for athletic purposes and Magnetic Resonance Imaging (MRI) is diffusely used to diagnose bone injuries (1-3). Despite the classification used in human medicine (4), in the equine practice the terms \u201cshort incomplete fracture\u201d, \u201cstress fractures\u201d, \u201cfissure, transchondral fracture\u201d and \u201costeochondral fracture\u201d are often used interchangeably. The purpose of the study was to report the case details, diagnostic imaging findings and outcomes in sport horses with a diagnosis of traumatic injuries at the articular surfaces of metacarpophalangeal and metatarsophalangeal joint (MCPJ/MTPJ) and verify if it is possibile to differentiate between subchondral, chondral and osteochondral fracture using a low-field MRI under general anesthesia. Material and methods Magnetic Resonance examination of horses referred for lameness localised to the fetlock region over a 7-year period were reviewed. Horses were selected for inclusion in the study that had MRI findings suggestive of primary bone lesion involving the articular surface of third metacarpal/metatarsal bone (MCIII/MTIII) or proximal phalanx (P1). Signalment, detailed clinical history, athletic use, MRI findings and follow-up informations were recorded. On the basis of MRI patterns, injuries at the articular surface were classified as osteochondral fractures (OF), chondral fractures (CF), or subchondral fractures (SF) (4). Lesions were identified as an OF when defect of cartilaginous lining and/or signal change of the cartilage layer was observed in association with subchondral bone marrow lesion and arcuate or linear irregular signal change in the subchondral bone. In the SF there was no involvement of the cartilaginous lining, while in the CF there is a displaced fragment and no alteration of the subchondral black line. Results Thirteen horses have been included in the study; five horses were used for show jumping, four for flat race, two for monta vaquera and two for eventing and dressage, respectively. The median age was 8.5 years of age, with a range between 2 and 16 yo. All horses had unilateral lameness, seven horses with acute onset, while six had a chronic lameness (>12 weeks). The degree of lameness varied from grades 2/5 to 4/5. In four horses lameness was localised to the hindlimb. In four horses a subtle, radiolucent, ill-defined line was observed in the radiographic views, suggestive of short incomplete fracture. Six horses had MRI findings suggestive of OF (impacted type) involving the sagittal groove of P1 in three cases, the medial aspect of P1 in one horse and the medial condyle of MCIII/MTIII in two horses. Seven horses had SF at the medial condyle of MCIII/MTIII in three cases, at the lateral condyle of MCIII/MTIII in two cases and involving the sagittal goove of the proximal phalanx in the last two cases. No MRI findings suggestive of CF were observed in the present study. In six horses no other abnormalities were detected while in seven cases additional alterations were observed, including mild desmopathy of MCPJ/MTPJ collateral ligaments, desmopathy of the suspensory ligament branches, oblique sesamoidean ligament alteration or adhesions between deep digital flexor tendon and distal sesamoidean impar ligament. All horses were treated with a period of rest; four horses received a therapy with biphosphonates and one horse was treated with intra-articular jaluronic acid. Median time of the final follow up was 32 weeks (range: 12 to 40 weeks). Of the 13 horses included in the study, nine (69%) were sound and returned to thier previous athletic use. Three horses were still lame due to MCPJ/MTPJ pain while another one was lame due to pain localised to the suspensory ligament origin. Conclusion In equine practice, the terms osteochondral fractures, tranchondral fractures, short fracture and incomplete fracture were used interchangeably. Differentiating between osteochondral and subchondral fractures is mandatory for an accurate prognosis (4). Even if low-field MRI has a low sensitivity in detecting articular surface damage (3,5), in the present study was possible to discriminate between OF and SF in all cases. Fat-suppressed images had the capability to enhance occult bone lesions like bone marrow traumatic damage. Fat-suppressed and T1-Weighted sequences allowed to detect defect in the overlying articular surface. Despite the results reported by Gold et al. (2017) in the present study 70% of cases returned to previous athletic levels (1). Considering that all horses with a diagnosis of subchondral fracture were sound at the time of re-check while horses still lame had osteochondral fracture, we can speculate that subchondral fracture has a better prognosis. In our study all horses underwent a period of rest and none received a surgical management. Differentiating between SF and OF could help the surgeon in the treatment choice, conservative in case of subchondral injuries and surgical when cartilage involvement was detected (6,8). In the report of Smith at all. (2017), of 12 cases with a diagnosis of short incomplete fracture or osteochondral fracture, 11 returned to race after surgical repair. Even if radiographic examination can, in some cases, identify short incomplete fractures, magnetic resonance examination allows to evaluate the presence of cartilage involvement, bone marrow lesions and simultaneous soft tissue abnormalities (6). The early diagnosis of these lesions is mandatory to prevent repetiteve loading on damaged bone and possible extension to the cortex (7) that can led to catastrophic injuries In conclusion, MRI has to be considered the best imaging technique in the evaluation of an incomplete fractures, in order to differentiate between osteochondral and subchondral fractures for the elective treatment of a specific pathological entity

Injuries at the articular surface of bone in horses detected with low-field magnetic resonance imaging: 13 cases (2010-2017)

Aim of the study The purpose of the study was to report the case details, diagnostic imaging findings and outcomes in sport horses with a diagnosis of traumatic injuries (osteochondral, chondral and subchondral fractures) at the articular surfaces of metacarpophalangeal and metatarsophalangeal joint (MCPJ/MTPJ). Material and methods Magnetic Resonance (MRI) examination of horses referred for lameness localised to the fetlock region over a 7-year period were reviewed. Horses were selected for inclusion in the study that had MRI findings suggestive of primary bone lesion involving the articular surface of third metacarpal/metatarsal bone (MCIII/MTIII) or proximal phalanx (P1). Signalment, detailed clinical history, athletic use, MRI findings and follow-up informations were recorded. On the basis of MRI patterns, injuries at the articular surface were classified as osteochondral fractures (OF), chondral fractures (CF), or subchondral fractures (SF) (1). Lesions were identified as an OF when defect of cartilaginous lining and/or signal change of the cartilage layer was observed, in association with subchondral bone marrow lesion and arcuate or linear irregular signal change in the subchondral bone. In the SF there was no involvement of the cartilaginous lining, while in the CF there is a displaced fragment and no alteration of the subchondral black line. Results Thirteen horses have been included in the study; five horses were used for show jumping, four for flat race, two for monta vaquera and two for eventing and dressage, respectively. All horses had unilateral lameness, 12 horses with acute onset, while six had a chronic lameness (>12 weeks). The degree of lameness varied from grades 2/5 to 4/5. In four horses lameness was localised to the hindlimb. In four horses radiographic findings suggestive of short incomplete fractures were observed. Six horses had MRI findings suggestive of OF (impacted type) involving the sagittal groove of P1 in three cases, the medial aspect of P1 in one horse and the medial condyle of MCIII/MTIII in 2 horses. Seven horses had SF at the medial condyle of MCIII/MTIII in 3 cases, at the lateral condyle of MCIII/MTIII in 2 cases and involving the sagittal goove of the proximal phalanx in the last two cases. In six horses no other abnormalities were detected while in seven cases additional alterations were observed, including mild desmopathy of MCPJ/MTPJ collateral ligaments, desmopathy of the suspensory ligament branches, oblique sesamoidean ligament alteration or adhesions between deep digital flexor tendon and distal sesamoidean impar ligament. All horses were treated with a period of rest; four horses received a therapy with biphosphonates and one horse was treated with intra-articular jaluronic acid. Median time of the final follow up was 32 weeks (range: 12 to 40 weeks). Of the 13 horses included in the study, nine (69%) were sound and returned to thier previous athletic use. Three horses were still lame due to MCPJ/MTPJ pain while another one was lame due to pain localised to the suspensory ligament origin. Conclusion In equine practice, the terms osteochondral fractures, tranchondral fractures, short fracture and incomplete fracture were used interchangeably. Differentiating between osteochondral and subchondral fractures is mandatory for an accurate prognosis (1). Even if low-field MRI has a low sensitivity in detecting articular surface damage (2, 3), in the present study was possible to discriminate between OF and SF in all cases. Despite the results reported by Gold et al. (2017) in the present study 70% of cases returned to previous athletic levels (4). All horses with a diagnosis of SF were sound at the time of re-check while horses still lame had OF. In our study all horses underwent a period of rest and none received a surgical management. Differentiating between SF and OF could help the surgeon in the treatment choice, conservative in case of subchondral injuries and surgical when cartilage involvement was detected (5). Even if radiographic examination can identify short incomplete fractures, magnetic resonance examination allows to evaluate the presence of cartilage involvement, bone marrow lesions and soft tissue abnormalities (5). In conclusion, MRI has to be considered the best imaging technique in the evaluation of an incomplete fractures, in order to differentiate between OF and SF and opt for the elective treatment of a specific pathological entity

Magic angle nella RM a bassa intensità di campo: è solo un errore di posizionamento?

Scopo del lavoro. Nell\u2019interpretazione delle immagini di Risonanza Magnetica (RM) deve essere tenuto in considerazione che la posizione delle strutture tenodesmiche rispetto al campo magnetico pu\uf2 provocare un aumento di segnale delle stesse, mimando una lesione1,2,3,4,5,6. Tale artefatto viene definito \u201cMagic Angle\u201d ed \ue8 gi\ue0 stato descritto in letteratura a carico dei leg. collaterali (CL) del- l\u2019articolazione interfalangea distale (DIPJ)2,3,5,6 del tendine flessore profondo del dito (DDFT)1,4,5 e dei legamenti sesamoidei obliqui (OSL)3. Tale artefatto pu\uf2 presentarsi utilizzando sia sistemi RM ad alto che basso campo quando le strutture anatomiche prima elencate si posizionano a circa 54\ub0 rispetto al campo magnetico (CM). In nessuno studio per\uf2 vengono descritte le alterazioni di se- gnale riconducibili a Magic Angle a carico degli OSL utilizzando posizionamenti che mimino di- fetti conformazionali dell\u2019estremit\ue0 distale del cavallo (Toe-in/Toe-out). Lo scopo del presente stu- dio \ue8 quello di verificare la presenza di Magic Angle a carico degli OSL nel cavallo, utilizzando un tomografo a basso campo con CM verticale e posizionando l\u2019arto in modo tale da simulare difetti conformazionali. Gli autori si propongono inoltre di verificare quali sequenze, tra quelle comune- mente inserite in un protocollo standard, siano le pi\uf9 sensibili a tale artefatto. Materiali e metodi. Sono stati sottoposti ad esame RM utilizzando un tomografo a basso campo n=3 arti isolati sinistri di soggetti sottoposti ad eutanasia per ragioni non correlate allo studio. Ogni arto \ue8 stato posizionato mantenendo l\u2019asse sagittale perpendicolare al CM, mimando il posiziona- mento \u201cin-vivo\u201d con il soggetto in decubito laterale sinistro. Per ogni arto sono state eseguite scan- sioni RM lungo il piano trasversale, utilizzando un protocollo standard previsto per esami clinici in cavalli affetti da zoppia che comprendeva sequenze pesate in T1, T2, Proton Density (PD) e se- quenze ad inversione con soppressione del segnale lipidico (STIR). Per verificare l\u2019assenza di le- sioni a carico degli OSL sono state acquisite le scansioni mantenendo l\u2019arto in posizione neutra (0\ub0). Successivamente, ogni arto \ue8 stato ruotato lungo l\u2019asse sagittale di 4\ub0, 8\ub0, 12\ub0 e 16\ub0, sia in senso orario che antiorario e per ciascun grado di rotazione il protocollo RM \ue8 stato ripetuto. L\u2019intensit\ue0 di segnale a carico degli OSL \ue8 stata misurata in ogni sequenza e per ogni posiziona- mento impiegando un software dedicato. Ogni misurazione \ue8 stata ripetuta tre volte ed \ue8 stata poi calcolata la media. Il test t di sudent \ue8 stato quindi utilizzato per valutare la significativit\ue0 dell\u2019in- cremento di segnale rispetto alla media. La significativit\ue0 \ue8 stata ritenuta positiva con a=0,05. Risultati. Il segnale a carico OSL laterale e mediale con l\u2019arto in posizione neutra era pressoch\ue9 so- vrapponibile. \uc8 stato invece osservato come all\u2019aumentare del grado di rotazione si verificasse un aumento dell\u2019intensit\ue0 di segnale a carico dell\u2019uno o dell\u2019altro legamento. Infatti, ruotando l\u2019arto in senso orario (+4\ub0, +8\ub0, +12\ub0, +16\ub0) \ue8 stato osservato un incremento lineare di segnale dell\u2019OSL me- diale, posto verso l\u2019alto. Viceversa, ruotando l\u2019arto in senso antiorario, l\u2019aumento d\u2019intensit\ue0 del se- gnale si \ue8 verificato a carico dell\u2019OSL laterale, posto verso il basso. Nonostante l\u2019incremento linea- re di segnale e la corrispondenza tra localizzazione dell\u2019iperintensit\ue0 e direzione della rotazione, una significativit\ue0 statistica \ue8 stata osservata solo con rotazioni di 16\ub0 e -16\ub0. Conclusioni. Nel presente studio \ue8 stato osservato come, in tutte le sequenze, ad un incremento del grado di rotazione corrispondesse un aumento del segnale legamentoso riconducibile a Magic An- gle. \uc8 stata inoltre riscontrata una stretta relazione tra localizzazione dell\u2019iperintensit\ue0 e direzione della rotazione. Gli scarsi valori di significativit\ue0 statistica possono essere ricondotti alla ridotta nu- merosit\ue0 del campione ma soprattutto agli elevati valori di deviazione standard dovuti alla presen- za di segnale disomogeneo caratteristico degli OSL. Sebbene in letteratura sia stato descritto che l\u2019aumento del Tempo di Eco (TE) possa ridurre, fino ad annullare, la presenza del Magic Angle6, nel presente studio, utilizzando le sequenze normal- mente impiegate in esami RM di tipo clinico, tale evenienza non \ue8 stata osservata. Un corretto posizionamento dell\u2019arto all\u2019interno del CM \ue8 indispensabile per ovviare alla compar- sa del Magic Angle. Tuttavia, in presenza di rotazioni del piede secondo il piano soleare identifica- bili come Toe in/Toe out, \ue8 opportuno prestare molta attenzione all\u2019aumento di segnale osservabile a carico degli OSL al fine di non commettere errori nella diagnosi ed interpretare la presenza di un artefatto come una desmopatia. Per questa ragione, in accordo con altri autori3, si consiglia di con- siderare come segno di patologia legamentosa non solo l\u2019iperintensit\ue0 di segnale ma anche varia- zioni nelle dimensioni e nella forma e l\u2019eventuale presenza di entesiofiti