Resonance Imaging Features Of Lesions Research Articles

Magnetic resonance imaging characteristics of lesions relate to the difficulty of peripheral arterial endovascular procedures

ObjectiveLimitations with current peripheral arterial imaging modalities make selection of patients for percutaneous vascular interventions difficult. The purpose of this study was to determine whether a novel preprocedural magnetic resonance imaging (MRI) method can identify lesions that would be more challenging to cross during percutaneous vascular intervention. MethodsFourteen patients with peripheral arterial disease underwent MRI before their intervention. A novel steady-state free precession flow-independent magnetic resonance (MR) angiogram was used to locate lesions, and an ultrashort echo time image was used to characterize hard lesion components including calcium and dense collagen. Lesions were characterized as hard if ≥50% of the lumen was occluded with calcium or collagen (as determined by MR image characteristics) in the hardest cross section within the lesion. The primary outcome was the time it took to cross a guidewire through the target lesion. The secondary outcome was the need for stenting. ResultsOf 14 lesions, 8 (57%) were defined as hard and 6 (43%) were soft on the basis of MR image characteristics. Hard lesions took significantly longer to cross than soft lesions (average, 14 minutes 49 seconds vs 2 minutes 17 seconds; P = .003). Hard lesions also required stenting more often than soft lesions (Fisher exact test, P = .008). Of 14 lesions, 2 (14%) could not be crossed with a guidewire, and both lesions were hard. MR images also detected occult patencies and noncalcified hard lesions that could not be seen on X-ray angiography. ConclusionsMRI can be used to determine which peripheral arterial lesions are more difficult to cross with a guidewire. Future work will determine whether MRI lesion characterization can predict long-term endovascular outcomes to aid in procedure planning.

Thrombosed Arteriovenous Malformations: A Type of Occult Vascular Malformation

Thrombosed arteriovenous malformations (AVMs) are the predominant type of occult vascular malformation and do not seem to differ significantly in clinical or radiographic presentation from other types of occult vascular malformations. Thrombosed AVMs and occult vascular malformations occasionally present with symptoms secondary to subacute or occult hemorrhage that requires operation. The histopathology of thrombosed AVMs and occult vascular malformations does not seem to have prognostic significance. Five patients with histologically verified thrombosed AVMs are reported. Two patients had previous incomplete resection of histologically proven thrombosed AVMs and presented with recurrence and bleeding. Two patients presented with seizures and headaches, and one patient presented with hemiparesis and headache. All histology specimens had evidence of hemorrhage. The pathological findings of these lesions seem variable; two specimens contained a mixture of cavernous angioma and AVM. Two previously resected lesions had been defined histologically as thrombosed AVMs. Successful excision of the lesions was accomplished in four patients, and one patient had stereotactic biopsy. The magnetic resonance imaging characteristics of lesions seem to add a degree of specificity over computed tomography and angiography. We have found that the literature poorly describes the natural history and histology of these lesions. Conservative management for seizures and headaches due to thrombosed AVMs may not be warranted because of a propensity for hemorrhage and recurrence.