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International Veterinary Epilepsy Task Force recommendations for a veterinary epilepsy-specific MRI protocol.

Rusbridge C, Long S, Jovanovik J, Milne M, Berendt M, Bhatti SF, De Risio L, Farqhuar RG, Fischer A, Matiasek K, Muñana K, Patterson EE, Pakozdy A, Penderis J, Platt S, Podell M, Potschka H, Stein VM, Tipold A, Volk HA - BMC Vet. Res. (2015)

Bottom Line: As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature.There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners.Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies.A 6-7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed.

View Article: PubMed Central - PubMed

Affiliation: Fitzpatrick Referrals, Halfway Lane, Eashing, Godalming, GU7 2QQ, Surrey, UK. ClareR@fitzpatrickreferrals.co.uk.

ABSTRACT
Epilepsy is one of the most common chronic neurological diseases in veterinary practice. Magnetic resonance imaging (MRI) is regarded as an important diagnostic test to reach the diagnosis of idiopathic epilepsy. However, given that the diagnosis requires the exclusion of other differentials for seizures, the parameters for MRI examination should allow the detection of subtle lesions which may not be obvious with existing techniques. In addition, there are several differentials for idiopathic epilepsy in humans, for example some focal cortical dysplasias, which may only apparent with special sequences, imaging planes and/or particular techniques used in performing the MRI scan. As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature.There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. A 6-7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed.

No MeSH data available.


Related in: MedlinePlus

Representative MRI from a 2.95 kg 5 year female entire Chihuahua dog that underwent a diagnostic investigation for cluster seizures. a Parasagittal image demonstrating the hippocampus and the planned imaging perpendicular to the long axis (b) Dorsal FLAIR images orientated perpendicular to long axis of the hippocampus demonstrating hyperintensity in the frontal lobe (short arrow). Although this protocol is optimised for detection of hippocampal lesions visualisation of other pathology is not compromised. c Dorsal T1W 3D images 1 mm slice thickness orientated perpendicular to long axis of the hippocampus. The scrolled structure of the hippocampus is clearly defined despite the small patient size. Furthermore the demarcation between white and grey matter can be appreciated (long arrow). d Post gadolinium T1W images are obtained in further investigation of the frontal lobe pathology. The patient was diagnosed subsequently with necrotising encephalitis. Images obtained in a 1.5 T MRI (Siemens Symphony, Erlangen, Germany)
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Fig10: Representative MRI from a 2.95 kg 5 year female entire Chihuahua dog that underwent a diagnostic investigation for cluster seizures. a Parasagittal image demonstrating the hippocampus and the planned imaging perpendicular to the long axis (b) Dorsal FLAIR images orientated perpendicular to long axis of the hippocampus demonstrating hyperintensity in the frontal lobe (short arrow). Although this protocol is optimised for detection of hippocampal lesions visualisation of other pathology is not compromised. c Dorsal T1W 3D images 1 mm slice thickness orientated perpendicular to long axis of the hippocampus. The scrolled structure of the hippocampus is clearly defined despite the small patient size. Furthermore the demarcation between white and grey matter can be appreciated (long arrow). d Post gadolinium T1W images are obtained in further investigation of the frontal lobe pathology. The patient was diagnosed subsequently with necrotising encephalitis. Images obtained in a 1.5 T MRI (Siemens Symphony, Erlangen, Germany)

Mentions: There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, complement pathological studies, is economical, simple to perform and can be adapted for both low and high field machines. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. We propose the following protocols (Tables 6 and 7). During protocol set-up, it is recommended that different parameters (such as flip angle) are trialed in order to obtain the optimal balance between grey-white matter contrast and SNR (for information on MR parameters for 0, 2, 1.5 and 3T see Additional files 1, 2 and 3). Both protocols start with obtaining a sagittal sequence. Due to the difference in anatomical definition this is a T2W sequence in high field machines and T1W sequence in low field machines. In addition to identifying gross structural pathology the sagittal images allow assessment of cerebellar atrophy according to the protocol described by Thames and others [37]. Using parasagittal images the long axis of the hippocampus is identified (Figs. 4, 5, 6, 7, 8 and 9). The hippocampus forms the medial wall of the temporal horn of the lateral ventricle and is delineated on parasagittal images by the contrasting cerebrospinal fluid. After identification of the hippocampus, T2W and sequences are orientated parallel and perpendicular to the long axis of the hippocampus (Figs. 4 and 7). T2W and FLAIR are acknowledged to be optimal for detection of epileptic lesions in humans in particular hippocampal changes (Figs. 2 and 3) and therefore in humans two FLAIR sequences would be obtained [38], however, it is recognized that performing two FLAIR sequences may increase scanning time significantly therefore we recommend that at a minimum a dorsal FLAIR sequence perpendicular to the long axis of the hippocampus is obtained with an option for an additional transverse sequence parallel to the long axis of the hippocampus. In high field scanners a transverse gradient echo or similar sequences sensitive to detection of hemosiderin and / or calcification should be obtained. Like the other images this transverse image is also orientated parallel to the hippocampus. In low field scanners additional T1W sequences are recommended (Table 5). Some high field machines may be able to obtain good resolution 3D TW1 images (Figs. 3, 8 and 10). For these the acquired slice thickness is 1 mm or less giving improved chance of lesion detection, better white and grey matter definition and can be processed after imaging into any anatomical plane including oblique. Furthermore this will facilitate volumetric measurements and to enable co-registration with other modalities or sequential MRI examinations [13, 38]. If this is not possible then a dorsal T1W sequence oriented along the long axis of the hippocampus is suggested. As indicated above there is an argument against routine paramagnetic contrast administration however it is acknowledged that many veterinary neurologists would feel a MRI study of an epileptic patient was incomplete without this therefore these sequences are an optional extra. However if pathology was detected in the unenhanced study, post-gadolinium sequences would be indicated (Fig. 10). Recommended slice thickness is 3 mm or less for high field machines and 4 mm or less for low field machines. Such a protocol would give 6–7 sequences for a high field machine and 6–7 sequences on a low field machine (not including optional paramagnetic contrast enhancement).Table 6


International Veterinary Epilepsy Task Force recommendations for a veterinary epilepsy-specific MRI protocol.

Rusbridge C, Long S, Jovanovik J, Milne M, Berendt M, Bhatti SF, De Risio L, Farqhuar RG, Fischer A, Matiasek K, Muñana K, Patterson EE, Pakozdy A, Penderis J, Platt S, Podell M, Potschka H, Stein VM, Tipold A, Volk HA - BMC Vet. Res. (2015)

Representative MRI from a 2.95 kg 5 year female entire Chihuahua dog that underwent a diagnostic investigation for cluster seizures. a Parasagittal image demonstrating the hippocampus and the planned imaging perpendicular to the long axis (b) Dorsal FLAIR images orientated perpendicular to long axis of the hippocampus demonstrating hyperintensity in the frontal lobe (short arrow). Although this protocol is optimised for detection of hippocampal lesions visualisation of other pathology is not compromised. c Dorsal T1W 3D images 1 mm slice thickness orientated perpendicular to long axis of the hippocampus. The scrolled structure of the hippocampus is clearly defined despite the small patient size. Furthermore the demarcation between white and grey matter can be appreciated (long arrow). d Post gadolinium T1W images are obtained in further investigation of the frontal lobe pathology. The patient was diagnosed subsequently with necrotising encephalitis. Images obtained in a 1.5 T MRI (Siemens Symphony, Erlangen, Germany)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4594743&req=5

Fig10: Representative MRI from a 2.95 kg 5 year female entire Chihuahua dog that underwent a diagnostic investigation for cluster seizures. a Parasagittal image demonstrating the hippocampus and the planned imaging perpendicular to the long axis (b) Dorsal FLAIR images orientated perpendicular to long axis of the hippocampus demonstrating hyperintensity in the frontal lobe (short arrow). Although this protocol is optimised for detection of hippocampal lesions visualisation of other pathology is not compromised. c Dorsal T1W 3D images 1 mm slice thickness orientated perpendicular to long axis of the hippocampus. The scrolled structure of the hippocampus is clearly defined despite the small patient size. Furthermore the demarcation between white and grey matter can be appreciated (long arrow). d Post gadolinium T1W images are obtained in further investigation of the frontal lobe pathology. The patient was diagnosed subsequently with necrotising encephalitis. Images obtained in a 1.5 T MRI (Siemens Symphony, Erlangen, Germany)
Mentions: There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, complement pathological studies, is economical, simple to perform and can be adapted for both low and high field machines. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. We propose the following protocols (Tables 6 and 7). During protocol set-up, it is recommended that different parameters (such as flip angle) are trialed in order to obtain the optimal balance between grey-white matter contrast and SNR (for information on MR parameters for 0, 2, 1.5 and 3T see Additional files 1, 2 and 3). Both protocols start with obtaining a sagittal sequence. Due to the difference in anatomical definition this is a T2W sequence in high field machines and T1W sequence in low field machines. In addition to identifying gross structural pathology the sagittal images allow assessment of cerebellar atrophy according to the protocol described by Thames and others [37]. Using parasagittal images the long axis of the hippocampus is identified (Figs. 4, 5, 6, 7, 8 and 9). The hippocampus forms the medial wall of the temporal horn of the lateral ventricle and is delineated on parasagittal images by the contrasting cerebrospinal fluid. After identification of the hippocampus, T2W and sequences are orientated parallel and perpendicular to the long axis of the hippocampus (Figs. 4 and 7). T2W and FLAIR are acknowledged to be optimal for detection of epileptic lesions in humans in particular hippocampal changes (Figs. 2 and 3) and therefore in humans two FLAIR sequences would be obtained [38], however, it is recognized that performing two FLAIR sequences may increase scanning time significantly therefore we recommend that at a minimum a dorsal FLAIR sequence perpendicular to the long axis of the hippocampus is obtained with an option for an additional transverse sequence parallel to the long axis of the hippocampus. In high field scanners a transverse gradient echo or similar sequences sensitive to detection of hemosiderin and / or calcification should be obtained. Like the other images this transverse image is also orientated parallel to the hippocampus. In low field scanners additional T1W sequences are recommended (Table 5). Some high field machines may be able to obtain good resolution 3D TW1 images (Figs. 3, 8 and 10). For these the acquired slice thickness is 1 mm or less giving improved chance of lesion detection, better white and grey matter definition and can be processed after imaging into any anatomical plane including oblique. Furthermore this will facilitate volumetric measurements and to enable co-registration with other modalities or sequential MRI examinations [13, 38]. If this is not possible then a dorsal T1W sequence oriented along the long axis of the hippocampus is suggested. As indicated above there is an argument against routine paramagnetic contrast administration however it is acknowledged that many veterinary neurologists would feel a MRI study of an epileptic patient was incomplete without this therefore these sequences are an optional extra. However if pathology was detected in the unenhanced study, post-gadolinium sequences would be indicated (Fig. 10). Recommended slice thickness is 3 mm or less for high field machines and 4 mm or less for low field machines. Such a protocol would give 6–7 sequences for a high field machine and 6–7 sequences on a low field machine (not including optional paramagnetic contrast enhancement).Table 6

Bottom Line: As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature.There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners.Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies.A 6-7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed.

View Article: PubMed Central - PubMed

Affiliation: Fitzpatrick Referrals, Halfway Lane, Eashing, Godalming, GU7 2QQ, Surrey, UK. ClareR@fitzpatrickreferrals.co.uk.

ABSTRACT
Epilepsy is one of the most common chronic neurological diseases in veterinary practice. Magnetic resonance imaging (MRI) is regarded as an important diagnostic test to reach the diagnosis of idiopathic epilepsy. However, given that the diagnosis requires the exclusion of other differentials for seizures, the parameters for MRI examination should allow the detection of subtle lesions which may not be obvious with existing techniques. In addition, there are several differentials for idiopathic epilepsy in humans, for example some focal cortical dysplasias, which may only apparent with special sequences, imaging planes and/or particular techniques used in performing the MRI scan. As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature.There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. A 6-7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed.

No MeSH data available.


Related in: MedlinePlus