MR of hereditary hemorrhagic telangiectasia: prevalence and spectrum of cerebrovascular malformations.

PURPOSE: Our goal was to describe the prevalence and types of cerebral vascular malformations (CVMs) seen with MR imaging in patients with hereditary hemorrhagic telangiectasia (HHT). METHODS: We reviewed retrospectively the brain MR images of 184 consecutive patients with HHT. Catheter angiography was performed in 17 patients with CVMs detected on MR images. RESULTS: MR imaging revealed 63 CVMs in 42 patients. Classic arteriovenous malformations (n = 10) had a conspicuous network of vessels with flow voids and enlarged adjacent pial vessels. Apparent venous malformations (n = 5) were best seen after administration of contrast material as a prominent vessel coursing through normal brain parenchyma. Indeterminate vascular malformations (n = 48) had a spectrum of appearances characterized by variable combinations of heterogeneous signal intensity, enhancement, or hemosiderin. Angiography in 17 patients revealed 47 CVMs. Forty-six were arteriovenous malformations (AVMs), including 25 CVMs not seen with MR imaging and 21 CVMs that by MR criteria included 8 AVMs and 13 indeterminate vascular malformations. Angiography confirmed 1 venous malformation seen with MR imaging but failed to detect 3 indeterminate lesions revealed by MR imaging. CONCLUSION: MR imaging of a large cohort of consecutive patients with HHT revealed a CVM prevalence of 23% (42/184). Most CVMs (48/63) have an atypical appearance for vascular malformations on MR images. Angiographic correlation suggests that MR imaging underestimates the prevalence of CVMs and that the majority of indeterminate CVMs, despite their variable MR appearance, are AVMs.

Clinical experience with gadolinium contrast agents in spinal MR imaging.

Gadolinium contrast agents represent one of the most important advances in MR imaging of spinal disease. Many abnormalities that affect the epidural, intradural extramedullary, and intramedullary compartments demonstrate contrast enhancement, the pattern of which often provides specific diagnostic information. This is particularly true of neoplastic diseases such as primary glioma and leptomeningeal tumor spread. Gadolinium contrast also finds vital application in differentiating herniated disc from epidural fibrosis in the failed-back surgery syndrome, as well as hypointense disc from enhancing tumor in select cases. Certain demyelinating and inflammatory processes also have predictable MR manifestations that facilitate accurate diagnosis.

Gated magnetic resonance imaging of the intracranial cerebrospinal fluid spaces.

The pulsatile nature CSF flow in the cerebral aqueduct has been demonstrated by du Boulay using air cineventriculography, a technique which disturbs normal CSF dynamics. To investigate this phenomenon non-invasively, we studied 35 normal volunteers using high-resolution, cardiac-gated magnetic resonance imaging (MRI). Specifically, we wished to document changes in size, configuration and signal intensity of the CSF spaces as they related to time in the cardiac cycle. Results show that changes in size and configuration were measurable in the third ventricle only (size increased during systole in 7 of the 35 volunteers). Except for the lateral ventricles, some loss in signal intensity was seen in all CSF spaces at least during systole, in all 35 volunteers-findings consistent with du Boulay's. However, contrary to du Boulay's observations, asymmetric loss of signal, consistent with pulsatile CSF flow, was demonstrated in the foramen of Monro in 15 of the 35 volunteers. Based on the pattern of signal void at the level of the foramen of Monro and on the expansion of the third ventricle during systole we propose a theory of synchronous CSF flow at the foramen of Monro and aqueduct, which unifies our MRI findings with du Boulay's cineventriculographic observations.