Capillary telangiectasias of the pons. Does diffusion-weighted MR increase diagnostic accuracy?

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Abstract

Background and Purpose

Capillary telangiectasias are benign lesions of the brainstem which are sometimes difficult to distinguish from other lesions in standard MRI. The purpose of this study was to evaluate if diffusion-weighted imaging (DWI) could help to improve diagnostic accuracy.

Methods

148 MR examinations of patients with pontine lesions were evaluated retrospectively and revealed capillary telangiectasia (n = 18), presumed microvascular disease (n = 20), encephalitis disseminata (n = 21), pontine myelinolysis (n = 16), tumor (n = 20), acute infarction (n = 20), subacute infarction (n = 13) and chronic infarction (n = 20).

All patients were examined using identical measurement parameters for DWI, Fluid attenuated inversion recovery, T2-weighted turbo spin-echo, and T1-weighted spin-echo before and after application of contrast agent in transverse orientation.

Results

All capillary telangiectasias showed low signal intensity in DWI and significant contrast enhancement after application of gadolinium. Hypointense signal on DWI was very rare for the remaining lesions: only 1 pontine myelinolysis, 1 tumor, 4 subacute infarctions, and 19 chronic infarctions also revealed low signal intensity on DWI. The combination of high signal intensity on T1-weighted post-contrast images and low signal intensity on DWI was found for all capillary telangiectasias, but only for 1/20 tumor and for 4/13 subacute infarctions. These lesions could be differentiated by their clinical course and/or MRI follow-up examinations.

The results of the visual assessment were confirmed by quantitative evaluation.

Conclusion

DWI seems to be a useful adjunct for the diagnosis of capillary telangiectasias which will facilitate the differential diagnosis concerning tumorous, inflammatory and ischemic lesions.

Introduction

Capillary telangiectasias refer to the cerebrovascular malformations of the central nervous system. They were first described by Russell and Rubinstein in 1959 [1]. Histologically they are composed of multiple thin walled capillary-like vessels separated by regular cerebral parenchyma which distinguishes them from cavernomas. Their most common localization is the brainstem, especially the pons. Much less common localizations are the cerebral hemispheres or the spine. The lesions have diameters ranging from several millimeters to 2 centimeters.

Their true incidence is not known. Based on autopsy reports they have a prevalence of approximately 0.4% representing 16–20% of all vascular malformations of the pons [2].

The clinical value of this lesion is still in discussion. In most cases they have a benign history. It is not clear yet if they lead to relevant clinical symptoms. Many different symptoms are mentioned in literature. Besides dizziness, nausea, ataxia, speech disorder, hyperreflexia, ptosis or paresthesia there is – to our knowledge – only one published case with a malign fatal progress [3].

Major complications such as ischemic infarcts, bleedings or change of local perfusion are rare. Most bleedings seem to arise from other associated vascular malformations such as cavernomas.

Magnetic resonance imaging (MRI) represents the standard of reference in diagnostic imaging of capillary telangiectasias. In most cases they are not detectable by catheter angiography or computed tomography (CT). Several typical and atypical features were described for MRI. But even using MRI the diagnosis is sometimes ambiguous. The lesions can be confused with other lesions, especially infectious and ischemic, as well as demyelinating or metastatic disease.

Because of the usually benign progress of capillary telangiectasias and the lack of therapeutic options invasive procedures should be avoided. To enable this a high specificity of diagnostic imaging methods is requested.

In a case report Fellner et al. already demonstrated the hypointense signal characteristics of a capillary telangiectasia using diffusion-weighted imaging (DWI) [4].

In this study we wanted to assess the accuracy and diagnostic benefit of DWI in characterizing capillary telangiectasias. Therefore we compared the MRI images of 18 patients with capillary telangiectasia to 130 consecutive patients with different pons lesions.

Section snippets

Material and methods

148 consecutive patients (83 male, 65 female, age ranging from 6 to 84 years (median age 56.6 ± 18.5 standard deviation)) with infratentorial lesions were evaluated retrospectively. In all patients the performed sequences used identical measurement parameters. To assess the characteristic appearance of capillary telangiectasias they were compared to other relevant pathologies located within or near the pons (e.g. neoplasms, inflammatory lesion, demyelinating disease, ischemic lesion).

According to

Results

Details of the visual evaluation are listed in Table 1 followed by ROI evaluation in Table 2.

The visual evaluation (Table 1) revealed hypointense (11/18) or isointense (7/18) signal of capillary telangiectasias compared to the surrounding pons tissue (Fig. 1a) in T1-weighted images. In T2-weighted images the lesions appeared isointense (6/18) or hyperintense (12/18) (Fig. 1b). Contrast enhanced T1-weighted images showed hyperintense signal in all capillary telangiectasias having an irregular

Discussion

Cerebral vascular malformations are classified into arteriovenous malformation (AVM), developmental venous anomalias (DVA), cavernomas and capillary telangiectasias. AVM, DVA and cavernomas have well known MRI criteria. AVM and DVA are detectable by angiography while cavernomas and capillary telangiectasias are usually not visible.

The current literature describes divergent criteria for MR imaging in capillary telangiectasias. Just a solid contrast uptake in T1-weighted sequences seems to be a

Conclusion

Regarding brainstem lesions, a high signal intensity in T1-weighted contrast enhanced images in combination with low signal intensity in DWI is an important and useful MRI indicator for a capillary telangiectasia. Especially the use of DWI enables a better differentiation of capillary telangiectasias to metastases or demyelinating lesions, which can show very similar appearance in standard MR sequences. Therefore, in the imaging of pontine lesions, we would recommend to apply diffusion-weighted

Conflict of interest

None.

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