首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
A 12‐year‐old mixed breed dog was presented for evaluation of progressive paraparesis and ataxia. Magnetic resonance (MR) imaging was performed and identified multifocal intradural spinal cord mass lesions. The lesions were hyperintense in T2‐weighted sequences, isointense to mildly hyperintense in T1‐weighted sequences with strong contrast enhancement of the intradural lesions and spinal cord meninges. Spinal cord neoplasia was suspected. A diagnosis of intramedullary spinal cord histiocytic sarcoma, confined to the central nervous system, was confirmed histopathologically. Spinal cord histiocytic sarcoma is a rare neoplasm, but should be included in the differential diagnosis for dogs with clinical signs of myelopathy.  相似文献   

2.
T2*‐weighted magnetic resonance imaging (MRI) has been reported to help improve detection of intracranial hemorrhage and is widely used in human neuroimaging. To assess the utility of this technique in small animals, interpretations based on this sequence were compared with those based on paired T2‐weighted and fluid‐attenuated inversion recovery (FLAIR) sequences in 200 dogs and cats that underwent brain MRI for suspected intracranial disease. Two sets of images (T2 + FLAIR and T2*) were reviewed separately in random order unaccompanied by patient information and were interpreted as normal or abnormal based on whether intracranial abnormalities were seen. The number and location of intracranial lesions were recorded. Eighty‐five studies were considered normal and 88 were considered abnormal based on both sets of images, with good agreement (κ = 0.731) between the two. Susceptibility artifact was present in 33 cases (16.5%) on T2*‐weighted images. In 12 cases (6%) a total of 69 lesions were seen on T2*‐weighted images that were not seen on T2/FLAIR, all of which were associated with susceptibility artifact caused by presumed intracranial hemorrhage. Pseudolesions were seen on T2*‐weighted images in five cases, none of which were associated with susceptibility artifact. Abnormalities were seen on T2/FLAIR images that were not seen on T2*‐weighted images in 35 cases, confirming that T2* does not replace standard spin echo sequences. These results support inclusion of T2*‐weighted sequences in small animal brain MRI studies and indicate that that a large number of abnormalities (especially hemorrhagic lesions) can go undetected if it is not performed.  相似文献   

3.
The suitability of low‐field magnetic resonance (MR) imaging for assessment of articular cartilage has been questioned, based on insufficient image quality. The purposes of this study were to describe the MR anatomy of the normal distal interphalangeal (DIP) cartilage, and to evaluate the sensitivity and accuracy of low‐field MR imaging for identification of cartilage erosions that were created ex vivo. Imaging sequences included sagittal and dorsal multiple‐oblique T1‐weighted gradient‐recalled echo (GRE) and sagittal dual echo sequences. In the thickest regions, normal cartilage appeared as a trilaminar structure on high‐resolution T1‐weighted GRE sequences. All 8 mm large full‐thickness erosions were correctly identified (100% sensitivity and accuracy) using T1‐weighted GRE sequences. Sensitivity and accuracy ranged from 80% to 100% and 10% to 80%, respectively, for detecting focal full‐thickness erosions and from 35% to 80% and 35% to 60%, respectively, for detecting partial thickness erosions, using T1‐weighted GRE sequences. Superficial irregularities were not diagnosed using any sequence. Overall, fewer cartilage alterations were detected with sagittal dual echo sequences than with sagittal T1‐weighted GRE sequences. The dorsal multiple‐oblique plane was useful to detect linear dorsopalmar erosions. A combination of T1‐weighted GRE sequences in two planes has potential for identification of severe DIP cartilage erosion in anesthetized horses using low‐field MR imaging.  相似文献   

4.
In order to compare the accuracy of MR sequences for diagnosis of meningeal disease, MR images of the brain, and histopathologic specimens including the meninges of 60 dogs were reviewed retrospectively by independent observers in a cross‐sectional study. MR images included T1‐weighted pre‐ and postgadolinium images, subtraction images, T2‐weighted images, and T2‐weighted fluid‐attenuated inversion‐recovery (FLAIR) images. Pathologic changes affected the pachymeninges in 16 dogs, leptomeninges in 35 dogs, and brain in 38 dogs. The meninges were normal in 12 dogs. Meninges were classified histopathologically as normal (grade 0), slightly or inconsistently affected (grade 1), or markedly affected (grade 2). When applying relaxed pathologic criteria (grades 0 and 1 considered normal), the results of ROC analysis (area under curve, AUC) were: T1‐weighted postcontrast images 0.74; subtraction images 0.7; T2‐weighted images 0.68; FLAIR images 0.56. The difference in AUC between T1‐weighted postgadolinium images and FLAIR images was significant (P = 0.04). AUC for FLAIR images was not significantly different from 0.5. When applying strict pathologic criteria (only grade 0 considered normal), none of the MR sequences had AUC significantly different from 0.5. On the basis of T1‐weighted postgadolinium images and subtraction images, correct anatomic classification of lesions occurred more often for pachymeningeal than leptomeningeal lesions (P < 0.001). Overall, MR imaging had low sensitivity for diagnosis of meningeal pathology in dogs, particularly for changes affecting the leptomeninges. Subtraction images had similar accuracy to T1‐weighted postgadolinium images for meningeal lesions in dogs. T2‐weighted FLAIR images appear to have limited diagnostic utility for meningeal lesions.  相似文献   

5.
Intracranial hemangioma is a rare intraaxial hemorrhagic neoplasm with imaging characteristics similar to other intracranial hemorrhagic lesions. We describe two canine cerebral hemangiomas that appeared as poorly circumscribed intraaxial compressive lesions that were predominantly hypointense on T2 sequences and heterogeneously contrast enhancing. Both lesions had perilesional edema and were hypointense on T2*‐gradient recalled echo sequences, consistent with hemorrhage. In one tumor a short partial peripheral rim was present, which was suggestive of hemosiderin deposition. Cerebral hemangioma should be included as a differential for hemorrhagic intracranial lesions.  相似文献   

6.
  相似文献   

7.
We compared the ability of 1.5 T magnetic resonance imaging (MRI), computed tomography (CT), and computed radiography (CR) to evaluate noncartilaginous structures of the equine metacarpophalangeal joint (MCP), and the association of imaging changes with gross cartilage damage in the context of osteoarthritis. Four CR projections, helical single‐slice CT, and MRI (T1‐weighted gradient recalled echo [GRE], T2*‐weighted GRE with fast imaging employing steady‐state acquisition [FIESTA], T2‐weighted fast spin echo with fat saturation, and spoiled gradient recalled echo with fat saturation [SPGR‐FS]) were performed on 20 racehorse cadaver forelimbs. Osteophytosis, synovial effusion, subchondral bone lysis and sclerosis, supracondylar lysis, joint fragments, bone marrow lesions, and collateral desmopathy were assessed with each modality. Interexaminer agreement was inferior to intraexaminer agreement and was generally moderate (i.e., 0.4<κ<0.6). Subchondral bone sclerosis scores using CT or MRI were correlated significantly with the reference quantitative CT technique used to assess bone mineral density (P<0.0001). Scores for subchondral lysis and osteophytosis were higher with MRI or CT vs. CR (P<0.0001). Although differences between modalities were noted, osteophytosis, subchondral sclerosis, and lysis as well as synovial effusion were all associated with the degree of cartilage damage and should be further evaluated as potential criteria to be included in a whole‐organ scoring system. This study highlights the capacity of MRI to evaluate noncartilaginous changes in the osteoarthritic equine MCP joint.  相似文献   

8.
Early detection of liver metastases may improve the prognosis for successful treatment in dogs with primary tumors. Hepatobiliary‐specific contrast agents have been shown to allow an increase in magnetic resonance imaging (MRI) detection of liver metastases in humans. The purpose of this prospective study was to test the feasibility for using one of these agents, gadobenate dimeglumine, to detect liver metastases in dogs. Ten consecutive dogs known to have a primary tumor were recruited for inclusion in the study. All dogs were scanned using the same protocol that included a T2‐weighted respiratory‐triggered sequence, T1 VIBE, diffusion‐weighted imaging, and 3D‐FLASH before and after dynamic injection of gadobenate dimeglumine contrast medium. Delayed imaging was performed less than 30 min after injection and up to 60 min in two cases. Histological analysis of liver lesions identified in delayed phases was performed for each case and confirmed metastatic origin. In all cases, lesion number detected in hepatobiliary contrast‐enhanced sequences was statistically higher than in other sequences. Optimal lesion detection occurred with a 3D‐FLASH sequence acquired in the transverse plane and less than 30 min after injection. Findings indicated that gabobenate dimeglumine enhanced MRI is a feasible technique for detecting liver metastases in dogs.  相似文献   

9.
Reasons for performing study: To determine the reliability of 2 magnetic resonance imaging (MRI) systems for detection of cartilage and bone lesions of the equine fetlock. Objectives: To test the hypotheses that lesions in cartilage, subchondral and trabecular bone of the equine fetlock verified using histopathology can be detected on high‐ and low‐field MR images with a low incidence of false positive or negative results; that low‐field images are less reliable than high‐field images for detection of cartilage lesions; and that combining results of interpretation from different pulse sequences increases detection of cartilage lesions. Methods: High‐ and low‐field MRI was performed on 19 limbs from horses identified with fetlock lameness prior to euthanasia. Grading systems were used to score cartilage, subchondral and trabecular bone on MR images and histopathology. Sensitivity and specificity were calculated for images. Results: High‐field T2*‐weighted gradient echo (T2*W‐GRE) and low‐field T2‐weighted fast spin echo (T2W‐FSE) images had high sensitivity but low specificity for detection of cartilage lesions. All pulse sequences had high sensitivity and low–moderate specificity for detection of subchondral bone lesions and moderate sensitivity and moderate–high specificity for detection of trabecular bone lesions (histopathology as gold standard). For detection of lesions of trabecular bone low‐field T2*W‐GRE images had higher sensitivity and specificity than T2W‐FSE images. Conclusions: There is high likelihood of false positive results using high‐ or low‐field MRI for detection of cartilage lesions and moderate–high likelihood of false positive results for detection of subchondral bone lesions compared with histopathology. Combining results of interpretation from different pulse sequences did not increase detection of cartilage lesions. MRI interpretation of trabecular bone was more reliable than cartilage or subchondral bone in both MR systems. Potential relevance: Independent interpretation of a variety of pulse sequences may maximise detection of cartilage and bone lesions in the fetlock. Clinicians should be aware of potential false positive and negative results.  相似文献   

10.
Tendon injuries are common in athletic humans and horses. Ultrasonography is the diagnostic method of choice in horses with tendon injuries but there is increasing application of magnetic resonance (MR) imaging to monitor and follow‐up tendon healing. A core lesion was created in the superficial digital flexor tendon (SDFT) of each forelimb of four horses. One of the four horses was euthanized at 2, 4, 8, and 12 weeks after creation of the lesion. MR examinations of the SDFT were performed immediately post mortem in a 1.5 T Siemens Symphony magnet and compared with histologic findings. Measurements from the MR images were also compared to ultrasonographic measurements available from the same lesions. Tendon lesions appeared as well‐circumscribed hyperintensities in the core of the SDFT on all pulse sequences. Lesions were most conspicuous on fat‐suppressed fast low angle shot (FLASH) sequences and least conspicuous on T2 transverse dual turbo spin echo (T2 TSE) sequences. The signal‐difference‐to‐noise ratio decreased with the age of the lesion in all sequences in this study. Twelve‐week‐old lesions were not visible on T2 TSE images but in all other sequences the lesion remained hyperintense. The lesion volume and maximum cross‐sectional area of core lesions were significantly smaller in T2 TSE images than in other MR sequences. The lesion volume and maximum cross‐sectional area of core lesions were significantly larger in proton density, T1, and FLASH sequences and significantly smaller in T2 sequences than when measured from ultrasonographic images. Through comparison between sequences, MR imaging may be able to provide information on various stages of tendon healing.  相似文献   

11.
Diseases of paranasal sinuses and nasal passages in horses can be a diagnostic challenge because of the complex anatomy of the head and limitations of many diagnostic modalities. Our hypothesis was that magnetic resonance (MR) imaging would provide excellent anatomical detail and soft tissue resolution, and would be accurate in the diagnosis of diseases of the paranasal sinuses and nasal passages in horses. Fourteen horses were imaged. Inclusion criteria were lesions located to the sinuses or nasal passages that underwent MR imaging and subsequent surgical intervention and/or histopathologic examination. A low field, 0.3 tesla open magnet was used. Sequences in the standard protocol were fast spin echo T2 sagittal and transverse, spin echo T1 transverse, short‐tau inversion recovery (STIR) dorsal, gradient echo 3D T1 MPR dorsal (plain and contrast enhanced), spin echo T1 fatsat (contrast enhanced). Mean scan time to complete the examination was 53 min (range 39–99 min). Lesions identified were primary or secondary sinusitis (six horses), paranasal sinus cyst (four horses), progressive ethmoid hematoma (two horses), and neoplasia (two horses). The most useful sequences were fast spin echo T2 transverse and sagittal, STIR dorsal and FE3D MPR (survey and contrast enhanced). Fluid accumulation, mucosal thickening, presence of encapsulated contents, bone deformation, and thickening were common findings observed in MR imaging. In selected horses, magnetic resonance imaging is a useful tool in diagnosing lesions of the paranasal sinuses and nasal passages.  相似文献   

12.
Central European tick‐borne encephalomyelitis can be challenging to diagnose in dogs because the virus may not be detected in blood and cerebrospinal fluid (CSF) after the first viremic stage of the disease. The purpose of this retrospective case series study was to describe 3 Tesla magnetic resonance imaging (3T MRI) findings in a sample of dogs with a confirmed diagnosis of tick‐borne encephalomyelitis. Dogs were included if they had neurological signs consistent with tick‐borne encephalomyelitis, history of a stay in endemic areas for tick‐borne encephalomyelitis virus, 3T MRI of the brain and/or spinal cord, cerebrospinal fluid changes compatible with viral infection and positive antibody titers in cerebrospinal fluid or pathologic confirmation of tick‐borne encephalomyelitis. Twelve dogs met inclusion criteria. Ten out of 12 patients had 3T MRI lesions at the time of presentation. One patient had persistent lesions in follow‐up MRI. The 3T MRI findings included bilateral and symmetrical gray matter distributed lesions involving the thalamus, hippocampus, brain stem, basal nuclei, and ventral horn on the spinal cord. All lesions were hyperintense in T2‐weighted sequences compared to white matter, iso‐ to hypointense in T1‐weighted, nonenhancing, and had minimal or no mass effect or perilesional edema. Six patients survived while the remaining six dogs were euthanized. Necropsy revealed neuronophagia and gliosis of the gray matter of the affected regions seen in 3T MRI, in addition to the cerebellum. Findings from the current study indicated that tick‐borne encephalomyelitis should be included in the differential diagnosis list for dogs with the above described 3T MRI characteristics.  相似文献   

13.
A 10‐year‐old, castrated male domestic short‐haired cat was presented with an acute history of seizures, lethargy, anorexia, vomiting, and dyspnea. Magnetic resonance imaging of the brain showed multifocal areas of gray matter T2‐weighted hyperintensity. The lesions did not enhance with intravenous contrast. The cat was diagnosed at necropsy with feline systemic reactive angioendotheliomatosis, a rare vascular proliferative disorder for which a treatment has not yet been identified. This report is the first to describe associated magnetic resonance imaging changes for this disease.  相似文献   

14.
An 8‐year‐old, male Boxer was examined for an acute onset of ambulatory paraparesis. Neurologic examination was consistent with a T3‐L3 myelopathy. Myelography revealed an extradural spinal cord compression in the region of the T10‐T13 vertebrae. On magnetic resonance (MR) imaging, a well‐defined epidural mass lesion was detected. The mass was mildly hyperintense on T1‐weighted, hyperintense on T2‐weighted and STIR images compared to normal spinal cord and enhanced strongly and homogenously. Postmortem examination confirmed a primary epidural hemangiosarcoma. Findings indicated that the MRI characteristics of spinal epidural hemangiosarcoma may mimic other lesions including meningioma and epidural hemorrhages/hematomas of non‐neoplastic etiology.  相似文献   

15.
Evaluation of the canine temporomandibular joint (TMJ) is important in the clinical diagnosis of animals presenting with dysphagia, malocclusion and jaw pain. In humans, magnetic resonance imaging (MRI) is the modality of choice for evaluation of the TMJ. The objectives of this study were to establish a technical protocol for performing MRI of the canine TMJ and describe the MRI anatomy and appearance of the normal canine TMJ. Ten dogs (one fresh cadaver and nine healthy live dogs) were imaged. MRIs were compared with cadaveric tissue sections. T1‐weighted (T1‐W) transverse closed‐mouth, T1‐W sagittal closed‐mouth, T1‐W sagittal open‐mouth, and T2‐W sagittal open‐mouth sequences were obtained. The condylar process of the mandible and the mandibular fossa of the temporal bone were hyperintense to muscle and isointense to hypointense to fat on T1‐W images, mildly hyperintense to muscle on T2‐W images, and were frequently heterogeneous. The articular disc was visible in 14/20 (70%) TMJs on T1‐W images and 13/20 (65%) TMJs on T2‐W images. The articular disc was isointense to hyperintense to muscle on T1‐W images and varied from hypointense to hyperintense to muscle on T2‐W images. The lateral collateral ligament was not identified in any joint. MRI allows evaluation of the osseous and certain soft tissue structures of the TMJ in dogs.  相似文献   

16.
Susceptibility weighted imaging (SWI) is a high resolution, fully velocity‐compensated, three‐dimensional gradient echo (GE) MRI technique. In humans, SWI has been reported to be more sensitive than T2*‐weighted GE sequences in the identification of both intracranial hemorrhage and intra‐vascular deoxyhemoglobin. However, published clinical studies comparing SWI to T2*‐weighted GE sequences in dogs are currently lacking. The aim of this retrospective, observational study was to compare SWI and T2*‐weighted GE sequences in a group of dogs with intracranial disease. Medical records were searched for dogs that underwent a brain MRI examination that included T2*‐weighted GE and SWI sequences. The presence and appearance of non‐vascular and vascular signal voids observed on T2*‐weighted GE and SWI were compared. Thirty‐two dogs were included with the following diagnoses: presumed and confirmed intracranial neoplasia (27), cerebrovascular accidents (3), and trauma (2). Hemorrhagic lesions were significantly more conspicuous on SWI than T2*‐weighted GE sequences (P < .0001). Venous structures were well defined in all SWI sequences, and poorly defined in all dogs on T2*‐weighted GE. Susceptibility weighted imaging enabled identification of vascular abnormalities in 30 of 32 (93.8%) dogs, including: neovascularization in 19 of 32 (59.4%) dogs, displacement of perilesional veins in five of 32 (15.6%) dogs, and apparent dilation of perilesional veins in 10 of 32 (31.3%) dogs. Presence of neovascularization was significantly associated with T1‐weighted post‐contrast enhancement (P = .0184). Hemorrhagic lesions and venous structures were more conspicuous on SWI compared to T2*‐weighted GE sequences. Authors recommend adding SWI to standard brain protocols in dogs for detecting hemorrhage and identifying venous abnormalities for lesion characterization.  相似文献   

17.
Bone marrow lesions (BMLs) (also known as ‘bone bruises’, ‘bone oedema’, ‘bone contusions’ and ‘occult fractures’) within the middle phalanx were diagnosed by standing low field magnetic resonance imaging (MRI) in 7 horses. The lesions were characterised by low signal intensity on T1‐ and T2*‐weighted gradient echo sequences, mildly increased signal intensity on T2 fast spin echo sequences, and high signal intensity on short tau inversion recovery (STIR) sequences. Four distinct patterns of abnormal signal were identified: BML associated with osteoarthritis of either the proximal or distal interphalangeal joints; BML associated with soft tissue injury; BML associated with acute trauma; and BML unassociated with any other injury or lameness (assumed to represent bone response to biomechanical stress). Repeat MRI was undertaken in 4 cases. In most cases the BML resolved with rest and time, although lameness was persistent in 2 horses (one of which had an associated osteoarthritis of the proximal interphalangeal joint).  相似文献   

18.
The T2*‐weighted gradient recalled echo sequence is a sensitive means to detect blood degradation products. While not a routine sequence in magnetic resonance imaging of the spine in small animals, it can provide additional valuable information in select cases. The goal of this retrospective, cross‐sectional study was to describe findings when acquiring this sequence during magnetic resonance imaging examination of the spine in small animals. The University of Tennessee's veterinary radiology database was searched for dogs and cats that underwent magnetic resonance imaging for suspect spinal disease in which a T2*‐weighted gradient recalled echo sequence was acquired and susceptibility artifact was identified. The following information was recorded: signalment, clinical signs, location and appearance of susceptibility artifact, and final diagnosis. Thirty‐nine cases were included in the study. Extradural susceptibility artifacts were observed in cases of intervertebral disc herniation with or without associated hemorrhage (n = 28), extradural hemorrhage associated with spinal trauma (n = 2), hemophilia (n = 1), and in a cystic extradural mass (n = 1). Remaining lesions displaying susceptibility artifact were intramedullary and included presumptive acute noncompressive nucleus pulposus extrusion (n = 2), hematoma (n = 1), hemangiosarcoma metastasis (n = 1), intramedullary disc extrusion (n = 1), presumptive meningomyelitis (n = 1), and a mass of undetermined etiology (n = 1). Inclusion of a T2*‐weighted gradient recalled echo sequence may be helpful in spinal magnetic resonance imaging when standard imaging sequences are ambiguous or intramedullary lesions are observed.  相似文献   

19.
An 8‐year‐old domestic short‐haired cat was presented with anorexia, lethargy, ataxia and one episode of consciousness loss. A midline vertically orientated, biconcave, extra‐axial mass originating from the basioccipital bone was detected on magnetic resonance images of the head. The mass was T1W iso‐ to hypointense when compared with normal grey matter, T2W hyperintense with small areas of isointensity and heterogeneously enhanced with contrast. Multiple signal voids were observed on T2* images. Histopathological evaluation confirmed a chordoma. To the authors’ knowledge this is the first report of the imaging characteristics of a chordoma affecting the skull base in a cat.  相似文献   

20.
The normal neonatal canine brain exhibits marked differences from that of the mature brain. With development into adulthood, there is a decrease in relative water content and progressive myelination; these changes are observable with magnetic resonance imaging (MRI) and are characterized by a repeatable and predictable time course. We characterized these developmental changes on common MRI sequences and identified clinically useful milestones of transition. To accomplish this, 17 normal dogs underwent MRI of the brain at various times after birth from 1 to 36 weeks. Sequences acquired were T1‐weighted (T1W), T2‐weighted (T2W), fluid attenuated inversion recovery, short tau inversion recovery, and diffusion weighted imaging sequences. The images were assessed subjectively for gray and white matter relative signal intensity and results correlated with histologic findings. The development of the neonatal canine brain follows a pattern that qualitatively matches that observed in humans, and which can be characterized adequately on T1W and T2W images. At birth, the relative gray matter to white matter signal intensity of the cortex is reversed from that of the adult with an isointense transition at 3–4 weeks on T1W and 4–8 weeks on T2W images. This is followed by the expected mature gray matter to white matter relative intensity that undergoes continued development to a mostly adult appearance by 16 weeks. On the fluid attenuated inversion recovery sequence, the cortical gray and white matter exhibit an additional signal intensity reversal during the juvenile period that is due to the initial high relative water content at the subcortical white matter, with its marked T1 relaxation effect.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号