Intra-arterial versus intra venous contrast-enhanced computed tomography of the equine head.

BACKGROUND: The anatomical complexity of the horse's head limits the abilities of radiography. Computed tomography (CT) in combination with contrast enhanced CT is used more often for diagnosing various head pathology in horses. The objective of this study was to compare intravenous and intra-arterial contrast-enhancement techniques and describe normal and abnormal contrast enhancement in the horse's head. RESULTS: All 24 horses included in the study recovered without complication from the procedures. Compared to the pre-contrast studies, post-contrast studies showed significant contrast enhancement in the pituitary gland (IA: p < 0.0001; IV: p < 0.0001), IA nose septum (p = 0.002), nose mucosa (IA: p < 0.0001; IV: p = 0.02), parotid salivary gland (IA: p < 0.0001; IV p < 0.0001), cerebrum (IA: p < 0.0001; IV: p < 0.0001), rectus capitis muscle (IA: p < 0.0001; IV p = 0.001), IA temporal muscle (p < 0.0001), IA masseter muscle (p <0.0001) and IV brainstem (p = 0.01). No significant contrast enhancement was seen in the eye (IA: p = 0.23; IV p = 0.33), tongue (IA p = 0.2; IV p = 0.57), IA brainstem (p = 0.88), IV nose septum (p = 0.26), IV temporal muscle (p = 0.09) and IV masseter muscle (p = 0.46). Three different categories of abnormal enhancement were detected: a strong vascularised mass, an enhanced rim surrounding an unenhanced structure and an inflamed anatomical structure with abnormal contrast enhancement. CONCLUSION: Using the intra-arterial technique, similar contrast enhancement is achieved using less contrast medium compared to the intravenous technique. And a potential major advantage of the IA technique is the ability to evaluate lesions that are characterized by increased blood flow. Using the intravenous technique, a symmetrical and homogenous enhancement is achieved, however timing is more crucial and the contrast dosage is more of influence in the IV protocol. And a potential major advantage of the IV technique is the ability to evaluate lesions that are characterized by increased vascular permeability. Knowing the different normal contrast enhancement patterns will facilitate the recognition of abnormal contrast enhancements.

Magnetic resonance imaging of the canine elbow: an anatomic study.

OBJECTIVES: To describe the normal anatomy of the soft tissues stabilizing the canine elbow observed by magnetic resonance (MR) imaging. STUDY DESIGN: Descriptive study. ANIMALS: Cadavers of large breed dogs (n=3). METHODS: Immediately after euthanasia, T1- and T2-weighted MR images of both elbows of each dog were made in sagittal, transverse, and dorsal planes. Elbows were removed from the cadavers, embedded in a water bath, and frozen. Slab sections of the frozen elbows were obtained and matched with the MR images. RESULTS: On anatomic sections, all musculoskeletal structures could be identified. T1-weighted MR images provided the best anatomic detail, whereas T2-weighted MR images were best for synovial cavities. All musculoskeletal structures identified on the anatomic sections were visible on the MR images. The flexor tendons were best seen on the images in the sagittal and dorsal planes, whereas the flexor carpi ulnaris tendon was best seen on the transverse images. The extensor tendons and the lateral collateral ligament were visible on the images in transverse and dorsal planes. The biceps brachii and triceps muscles and tendons were best seen on the sagittal MR images. CONCLUSIONS: MR is a useful imaging technique to observe the soft tissues of the canine elbow. CLINICAL RELEVANCE: This anatomic atlas could be used as a guide for interpretation of MR images of elbow disorders such as tendon, ligament, or muscle injuries.

Pre- and posttreatment ultrasonography of the thyroid gland in hyperthyroid cats.

Ultrasonography is useful for assessing the morphology of the thyroid gland in hyperthyroid cats. Our aim was to describe the ultrasonographic changes of the thyroid gland in hyperthyroid cats after 131I therapy. Ultrasonography was performed in 15 hyperthyroid cats at initial presentation and 6 months after 131I using a multifrequency linear transducer set at 12 MHz. The following criteria were evaluated: length, width, height, volume, shape, homogeneity, and vascularity, using Power Doppler. Pretreatment, 10 cats had bilaterally abnormal thyroid lobes, four cats one abnormal lobe with the contralateral lobe being normal or reduced in size, and one cat with one normal lobe and one lobe not visible. Six months after 131I therapy, there was a reduction in median volume from 819 to 210 mm3, reduced rounding, reduced heterogeneity, and decreased vascularity. In conclusion, ultrasonography may be used to monitor thyroid changes in order to assess 131I treatment response. Further studies are necessary to determine whether ultrasonography could contribute to the detection of a relapsing course of hyperthyroidism.