Mahmoud Mageed - Academia.edu (original) (raw)

Papers by Mahmoud Mageed

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The sheep spine is widely used as a model for preclinical research in human medicine to test new ... more The sheep spine is widely used as a model for preclinical research in human medicine to test new spinal implants and surgical procedures. Therefore, precise morphometric data are needed. The present study aimed to provide computed tomographic (CT) morphometry of sheep thoracolumbar spine. Five adult normal Merino sheep were included in this study. Sheep were anaesthetised and positioned in sternal recumbency. Subsequently, transverse and sagittal images were obtained using a multi-detector-row helical CT scanner. Measurements of the vertebral bodies, pedicles, intervertebral disc and transverse processes were performed with dedicated software. Vertebral bodies and the spinal canal were wider than they were deep, most obviously in the lumbar vertebrae. The intervertebral discs were as much as 57.4% thicker in the lumbar than in the thoracic spine. The pedicles were higher and longer than they were wide over the entire thoracolumbar spine. In conclusion, the generated data can serve as a CT reference for the ovine thoracolumbar spine and may be helpful in using sheep spine as a model for human spinal research.

Objectives: Sheep are frequently used as animal models in experimental spinal injury studies. The... more Objectives: Sheep are frequently used as animal models in experimental spinal injury studies. Therefore, extensive knowledge of ovine spinal dimensions is essential for experimental design and interpretation of results obtained in these trials. This study aimed to obtain quantitative morphometrical data of the thoracolumbar dural sac in sheep and determine the anatomical relationship between the dural sac and the vertebral canal. Methods: Computed assisted myelography imaging was carried out in five adult German Black-Headed Mutton sheep under general anaesthesia. Transverse images were acquired with 2 mm slice thickness from the first thoracic to the sixth lumbar vertebrae. Sagittal and transverse diameters and the cross-sectional area of the dural sac and vertebral canal were measured. To determine the anatomical relationship between the dural sac and vertebral canal, the pedicle-dural sac distance (PPSD) and the epidural space as well as the SAC (available space for the dural sac) were calculated. Results: Sagittal diameters of the dural sac ranged from 5.1 to 12.0 mm. Transverse diameters ranged from 5.6 to 12.2 mm. The dural sac area covered 45.9% and 49.0% of the thoracic and lumbar vertebral canal area. The PDSD in the lumbar vertebrae was up to 15.8% larger than in the thoracic ones. The dural sac area was significantly positively correlated with the transverse diameter and area of the vertebral canal. Clinical significance: The lumbar vertebral canal contained more space for the dural sac, which seems to be safer for testing spinal implants.

Morphometrical analysis of the thoracolumbar dural sac in sheep using computed assisted myelography. Available from: https://www.researchgate.net/publication/260055191_Morphometrical_analysis_of_the_thoracolumbar_dural_sac_in_sheep_using_computed_assisted_myelography [accessed Apr 16, 2017].

Sheep are commonly used as a model for human spinal orthopaedic research due to their similarity ... more Sheep are commonly used as a model for human spinal orthopaedic research due to their similarity in morphological and biomechanical features. This study aimed to document the volumes of vertebral bodies and compare the generated results as well as morphometry of the sheep lumbar spine to human published data. For this purpose, computed tomography scans were carried out on five adult Merino sheep under general anaesthesia. Transverse 5 mm thick images were acquired from L1 to L6 using a multi-detector-row helical CT scanner. Volume measurements were performed with dedicated software. Four spinal indices and Pavlov's ratio were calculated. Thereafter, the generated data were compared to published literature on humans. The mean vertebral body volume showed an increase towards the caudal vertebrae, but there were no significant differences between the vertebral levels (P>0.05). Compared to humans, sheep vertebral body volumes were 48.6% smaller. The comparison of absolute values between both species revealed that sheep had smaller, longer and narrower vertebral bodies, thinner intervertebral discs, narrower spinal canal, longer transverse processes, shorter dorsal spinous processes and narrower, higher pedicles with more lateral angulations. The comparison of the spinal indices showed a good similarity to human in terms of the vertebral endplates and spinal canal. The results of this study may be helpful for using the sheep as a model for human orthopaedic spinal research if anatomical differences are taken into account.

Zusammenfassung: Schmerzen in der proximopalmaren Metakarpalregion werden bei Pferden häufig als ... more Zusammenfassung: Schmerzen in der proximopalmaren Metakarpalregion werden bei Pferden häufig als Lahmheitsursache angesehen. Dabei ist die Diagnostik schwierig, oft wird per Ausschlussverfahren gearbeitet. Aus diesem Grund werden zunehmend verschiedene bild-gebende Verfahren ergänzend eingesetzt. Deren Aussagekraft ist dabei jedoch sehr unterschiedlich. Zuerst wird regelmäßig eine Röntgen-untersuchung durchgeführt, wobei bekannt ist, dass diese wenig sensitiv ist und viele Pferde keine Veränderungen aufweisen. Interessant ist in diesem Zusammenhang, inwiefern die Auswertung der Röntgenbilder durch unterschiedlich ausgebildete Untersucher einen Einfluss auf Sensitivität und Spezifität sowohl bei Röntgen-als auch bei szintigraphischen Untersuchungen aufweist. Hierfür wurden Pferde retrospektiv untersucht, bei denen sowohl röntgenologische als auch szintigraphische Untersuchungen durchgeführt wurden. 32 Beine von 23 Pferden erfüllten die Einschlusskriterien für eine Kontroll-und eine Untersuchungsgruppe. Die Röntgenbilder und Szintigramme der Pferde wurden von drei verschiedenen Untersuchern unterschiedlicher Erfahrung subjektiv verblindet beurteilt. Die Ergebnisse wiesen für beide Modalitäten nach, dass positive und negative Vorhersagewerte mit steigender Erfahrung des Untersuchers ansteigen. Bei der Röntgendiagnostik zeigte sich eine mittelmäßige Sensitivität (60,6 %) im Durchschnitt aller Untersucher, die Spezifität war etwas höher (65,1%) und der positive Vor-hersagwert erschien mäßig (50,9 %). Im Vergleich zur Röntgendiagnostik war die Szintigraphie deutlich sensitiver (90,9 %), die Spezifität (95,2 %) sowie der positive Vorhersagewert (90,9 %) ergaben bessere Ergebnisse. Der durchschnittliche Inter-Beurteiler Kappa erschien mit 0,23 gering für Röntgenbilder und etwas besser für Szintigramme (0,62). Die Übereinstimmung der beiden erfahrenen Beurteiler war für die Szintigraphie deutlich besser (0,93) als in allen anderen Varianten. Zusammenfassend kann bei der subjektiven Auswertung radiologi-scher und szintigraphischer Bilder im Bereich des proximopalmaren Metakarpus von einem erheblichen Einfluss der Erfahrung des Unter-suchers ausgegangen werden, der beim Röntgen deutlicher ausfällt. Die Röntgendiagnostik weist eine moderate Sensitivität und Spezifität auf. Mittels szintigraphischer Diagnostik kann dies verbessert werden. Es besteht eine geringe Übereinstimmung bei der Interpretation der Röntgenbilder und eine etwas bessere bei der Auswertung der Szintigramme. Der Kombination mehrerer diagnostischer Methoden wird nach wie vor ein hoher Stellenwert zugesprochen. Interobserver agreement, sensitivity and specificity for the diagnosis of horses with proximopalmar metacarpal lameness using radiography and scintigraphy – A retrospective study Lameness originating from the proximal metacarpal region is known as one of the most common causes of lameness in horses. Differential diagnosis is based on the exclusion of other possible causes. Diagnostic imaging modalities, such as radiography, ultrasonography and scintigraphy, are often used to ensure an accurate diagnosis. Radiography is used routinely, in clinical practice, often as the first modality to assess the integrity of the bone. However, radiography has been reported as an insensitive modality to assess changes in proximal meta-carpal region such as desmitis and/or insertion desmopathy of the proximal suspensory ligament, which can lead cause lameness. In addition , radiographs of this area can be difficult to interpret. Increased opacity of the proximal lateral aspect of the third metatarsal bone can be seen in some clinically normal horses, often bilaterally. This may reflect increased loading of the lateral aspect of the bone and stress-related remodeling. Nuclear scintigraphy can be extremely helpful in identifying stress-related bone injury typified by moderate or intense focal increased radiopharmaceutical uptake (IRU). However, a small proportion of horses with primary proximal suspensory desmitis show a similar pattern and intensity of IRU. Other horses with proximal suspensory desmitis have much less intense IRU compared with horses with a primary stress-related bone injury and, in many horses with primary suspensory ligament injury, radiopharmaceutical uptake is normal. Interestingly, these reports did not take the experience level of the interpreter into account. The current study therefore aimed to document the influence of the interpreter's experience on sensitivity and specificity of radiography and scintigraphy as diagnostic modalities for diagnosis proximal palmar metacarpal lameness. We hypothesised that sensitivity and specificity of radiography and scintigraphy for the diagnosis of proximal palmar metacarpal lameness increases with the experience of the interpreter. For this purpose, the medical records of horses which underwent a radiographic as well as scintigraphic examination of the proximal metacarpal region were reviewed. 32 limbs of 23 horses met the inclusion criteria of the study. Thereafter the horses were divided into two groups. The control group included the horses which were sound or had lameness located elsewhere than the proximal metacarpal region. The lame group included horses, which were diagnosed with lameness located at proximal metacarpal region using clinical examination, local anesthesia and other diagnostic modalities such as computed tomography, ultrasound and magnetic resonance imaging. The radiographs and the scintigraphs of each horse were examined blindly by three different interpreters with different levels of experience (certified radiologist, resident of ECVDI and intern). The results showed that the interpreter with high experience had higher positive and negative predicting value in both modalities compared to the less experienced interpreter. Radiography showed a sensitivity of 60.6 % and specificity of 65.1% with a positive predictive value of 50.9 % for all interpreters combined. In contrast, scintigraphy showed higher sensitivity (90.1%) and specificity (95 %) as well as positive predictive value (90.9 %) compared to radiography. The interobserver agreement was tested using Cohen kappa test and revealed bad agreement (0.23) between the interpreters for radiography, whereas it was better for scintigraphy (0.62). The agreement between the Interobserver-Übereinstimmung, Sensitivität und Spezifität bei der Röntgen-und Szintigraphiediagnostik M. Mageed et al.