MRI SEQUENCES T1: Provides good anatomical detail Fat = white Fluid= black T2: Emphasises the presence of fluid Fluid = white Fat= White (less than in T1) $9$1(:&$67/(

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T1

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MRI SEQUENCES STIR: Suppresses the fat signal Very sensitive to detect bone abnormalities. FAT= BLACK PDW: (proton density weighted): good detail and emphasises the distribution of fluid. Greater GREY SCALE $9$1(:&$67/(

STIR

Why MRI? ‡ ‡

PDW

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MRI General considerations: ‡ Signal:noise ratio ‡ Field strength ‡ Coil technology ‡ Sequences and parameters

‡ ‡ ‡

Magnetic Resonance Imaging is a cross sectional imaging modality Excellent contrast between soft tissue and bone Very sensitive to bony changes Allows cartilage assessment Combination of sequences allows further characterisation of the type of injury

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MRI Magnetic Resonance Imaging: ‡ Advanced medical imaging technology. ‡ The physics of MRI make this modality a very sensitive tool for detecting soft tissue and bone pathology. 05,UHOLHVRQWKHEHKDYLRXU RISURWRQV + ZLWKLQWKHERG\ZKHQZLWKLQD PDJQHWLFILHOG

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MRI CASES

MRI SEQUENCES USED IN MUSCULO-SKELETAL IMAGING T2

T1

EXTREMELY IMPORTANT !!!

Clinical history

Nerve blocks

Joint block

PDW

STIR

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NAVICULAR FRACTURE

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MRI EQUIPMENT AT THE UVTHC

‡4 year old WB gelding ‡History: Positive to palmar digital (p.d.) block ‡No radiological abnormalities were visualised ‡Worse after intrabursal treatment.

0.3 Tesla (low field magnet) Open magnet

NAVICULAR DISEASE ‡ ‡ ‡ ‡

8 year old warmblood History: RF intermittent lameness Palmar digital block positive Radiographs: medial vascular channel abnormally shaped.

LOW FIELD MRI Advantages : ‡ No general anaesthesia is required ‡ Less susceptible to artifacts ‡ Less susceptible to accidents ‡ Provides excellent contrast

NAVICULAR DISEASE

3rd TARSAL BONE CYST

‡ 9 Year old dressage stallion ‡ History: intermittent lameness in both front feet. ‡Lameness improved after short period of rest ‡ Positive response to p.d. block ‡ Radiographs: mild enthesiophytes proximal navicular bone ‡ \HDUROGTXDUWHUKRUVHVWDOOLRQ

Abnormal

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