Michele Puglioli

Silent Cerebral Ischemia Detected With Diffusion-Weighted Imaging in Patients Treated With Protected and Unprotected Carotid Artery Stenting

Background and Purpose— Percutaneous transluminal angioplasty with stent (CAS) is an alternative method to endarterectomy in the revascularization of carotid artery stenosis. Protected CAS is currently used to prevent distal embolization. Diffusion-weighted MRI (DWI) is the most sensitive tool to evaluate silent cerebral ischemia. The purpose of this research was to assess the incidence of cerebral embolic lesions during CAS and to evaluate whether cerebral protection devices can reduce the number of silent cerebral ischemia with respect to unprotected CAS. Methods— Fifty-two patients with high-grade internal stenosis underwent CAS; 30 patients (group a) were treated with a cerebral protection device, and 22 (group b) were treated without it. All of the patients were evaluated preoperatively and postoperatively with fluid-attenuated inversion recovery and DWI sequences to depict the number of new embolic silent cerebral lesions. Results— Embolic silent cerebral lesions occurred in 30% of CAS. Cerebral protection devices reduce the number of new lesions significantly reducing the consistent lesions ipsilateral to the treated vessel. Inconsistent lesions do not differ in both groups of patients. Clinical, radiological, and procedural variables do not correlate with the appearance of new cerebral lesions. Conclusions— Embolic cerebral lesions detected with DWI are more frequent with unprotected CAS, although they are present also with the use of cerebral protection devices. Probably a part of silent cerebral lesions arise from the procedural maneuver in the aortic arch.

Contrast-Enhanced Three-Dimensional Magnetic Resonance Angiography of Atherosclerotic Internal Carotid Stenosis as the Noninvasive Imaging Modality in Revascularization Decision Making

Background and Purpose— In patients with severe internal carotid artery stenoses, thromboendarterectomy significantly reduces both ischemic stroke and the risk of more ischemic attacks. Digital subtraction angiography (DSA) is the accepted preoperative test to determine whether a high-grade stenosis is present and requires surgical therapy. However, DSA has a procedural risk of stroke between 0.7% and 1%. An accurate, noninvasive imaging protocol with no risk of severe complications would significantly increase the benefit of surgical treatment. The aims of the study were (1) to evaluate the diagnostic accuracy of contrast-enhanced magnetic resonance angiography (CEMRA) in detecting and grading internal carotid artery stenoses and (2) to assess the misclassification rate of vessels suitable for revascularization by CEMRA. Methods— Ninety-two patients with sonographic evidence of neck vessel stenosis were enrolled in the study. All patients were submitted to CEMRA and DSA. CEMRA images were evaluated for the presence of mild, moderate, or severe stenosis and occlusion. Results— Sensitivity, specificity, and diagnostic accuracy were 97%, 82%, and 92.5%, respectively. Agreement with DSA was optimal at &kgr;=0.87. The misclassification rate of CEMRA was 3.1% because of its tendency to overestimate the stenosis. Conclusions— The high diagnostic accuracy and limited misclassification rate suggest that CEMRA can be considered a powerful tool for the preoperative, noninvasive evaluation of atherosclerotic pathology of carotid arteries.

Epidural Spinal Cavernous Hemangioma

Study Design. Five cases of epidural spinal cavernous hemangioma submitted to magnetic resonance imaging and surgery were reviewed. Objective. To correlate different magnetic resonance imaging appearances of epidural spinal cavernous hemangioma with histologic findings. Summary of Background Data. Cavernous hemangioma is an uncommon vascular malformation that may occur anywhere in the central nervous system. Purely epidural lesions are very rare. Accurate correlation between magnetic resonance imaging appearances and histologic findings have not been reported in the literature. Methods. Five cases of epidural spinal cavernous hemangioma that had undergone magnetic resonance imaging evaluation followed by microsurgical removal, were retrospectively reviewed. Conventional spin‐echo T1‐, proton density‐ and T2‐weighted magnetic resonance images were obtained in all cases, and gadolinium was used in all but one. Two cases have also been evaluated with computed tomography. Results. In two cases, magnetic resonance imaging showed mixed low‐ and high‐signal intensity components in all sequences and pathologic examination showed degenerative phenomena and hemosiderin pigments. In the remaining three cases, magnetic resonance imaging showed low‐ or intermediate‐signal intensity on T1‐weighted and high‐signal intensity on proton density‐ and T2‐weighted images. In those cases, pathologic examination showed an absence of degenerative phenomena and no signs of hemorrhage. All patients underwent surgery by laminectomy and microsurgical resection. In all, significant improvement was obtained. Conclusions. Epidural spinal cavernous hemangioma has a different magnetic resonance imaging appearance probably because of the presence or absence of the degenerative phenomena and hemosiderin pigments. As in cerebral locations, mixed signal intensity in all sequences on magnetic resonance images might be indicative of cavernous hemangioma. Presumptive preoperative diagnosis of the lesion may render the surgical approach less invasive.

In Stent Restenosis Predictors after Carotid Artery Stenting

Purpose. The long-term efficacy of carotid artery stenting is debated. Predictors of stent restenosis are not fully investigated. Our aim was to assess the incidence of long term restenosis after CAS and to identify some predictors of restenosis. Methods. We retrospectively selected 189 treated patients and we obtained the survival Kaplan-Meier curves for overall survival, for freedom from stroke or death and from restenosis. To correlate clinical, radiological, and procedural variables to stent restenosis, an univariate analysis was performed while to determine independent predictors of restenosis, a multivariate analysis was applied. Results. At 1, 3, and 5 years, the cumulative overall survival rate was 98%, 94%, and 92% with a cumulative primary patency rate of 87%, 82.5%, and 82.5%. The percentage residual stenosis after CAS and multiple stents deployment were independent predictors of restenosis, while diabetes and tumors are suggestive but not significant predictors of restenosis. Conclusions. In our CAS experience, encouraging long-term results seem to derive from both neurological event free rate and restenosis incidence. Adequate recanalization of the treated vessel is important to limit the development of stent restenosis. Multiple stents deployment, and with less evidence, diabetes, or neoplasms has to be considered to facilitate restenosis.

Contrast-enhanced three-dimensional MR angiography of neck vessels: does dephasing effect alter diagnostic accuracy?

Abstract. The aim of this study was to evaluate diagnostic accuracy of contrast-enhanced MRA (CEMRA) compared with digital subtraction angiography (DSA) in studying neck vessels of 48 patients. In three groups of patients, we used three MRA protocols differing for voxel size to assess if intravoxel dephasing effects could modify accuracy of CEMRA. Accuracy and correlation with DSA results were calculated in all patients and separately in the three groups. A qualitative analysis of the likeness between morphology of the stenosis in CEMRA and DSA images was also assessed. In all patients accuracy and agreement with DSA were 96% and k=0.85 in subclavian arteries, 96% and k=0.84 in vertebral artery, 97% and k=0.88 in common carotid arteries, and 94% and k=0.86 in internal carotid arteries. In the three groups accuracy and agreement with DSA did not show any significant difference. Qualitative analysis of CEMRA and DSA images revealed a better agreement in depicting the morphology of stenosis using a smaller voxel size. The CEMRA represents a powerful tool for the non-invasive evaluation of neck vessels. Overestimation trend of CEMRA is confirmed and the reduction of voxel size, decreasing the dephasing intravoxel effect, allows to have a better overlapping of stenosis morphology on CEMRA compared with DSA, but it does not yield diagnostic gain in the stenosis grading.

Spontaneous regression of intracranial arteriovenous malformation

Spontaneous regression of an arteriovenous malformation is rare. When complete or partial regression occurs, an associated factor is usually involved, such as intracranial hemorrhage, surgery, radiation therapy, or a new neurological deficit. Another case in which the resolution was totally spontaneous is presented here. We discuss the importance of transcranial doppler revealing the hemodynamic changes in the cerebral arteries in the presence of an AVM and when the latter is thrombosed. Several mechanisms for regression are considered, and we focus on the dissection of the afferent vessel, pointing out the role of such an event in the natural history of AVM.

Optimizing the Balance Between Radiation Dose and Image Quality in Pediatric Head CT: Findings Before and After Intensive Radiologic Staff Training

OBJECTIVE The purpose of this study was to assess the radiation dose and image quality of pediatric head CT examinations before and after radiologic staff training. MATERIALS AND METHODS Outpatients 1 month to 14 years old underwent 215 unenhanced head CT examinations before and after intensive training of staff radiologists and technologists in optimization of CT technique. Patients were divided into three age groups (0-4, 5-9, and 10-14 years), and CT dose index, dose-length product, tube voltage, and tube current-rotation time product values before and after training were retrieved from the hospital PACS. Gray matter conspicuity and contrast-to-noise ratio before and after training were calculated, and subjective image quality in terms of artifacts, gray-white matter differentiation, noise, visualization of posterior fossa structures, and need for repeat CT examination was visually evaluated by three neuroradiologists. RESULTS The median CT dose index and dose-length product values were significantly lower after than before training in all age groups (27 mGy and 338 mGy ∙ cm vs 107 mGy and 1444 mGy ∙ cm in the 0- to 4-year-old group, 41 mGy and 483 mGy ∙ cm vs 68 mGy and 976 mGy ∙ cm in the 5- to 9-year-old group, and 51 mGy and 679 mGy ∙ cm vs 107 mGy and 1480 mGy ∙ cm in the 10- to 14-year-old group; p < 0.001). The tube voltage and tube current-time values after training were significantly lower than the levels before training (p < 0.001). Subjective posttraining image quality was not inferior to pretraining levels for any item except noise (p < 0.05), which, however, was never diagnostically unacceptable. CONCLUSION Radiologic staff training can be effective in reducing radiation dose while preserving diagnostic image quality in pediatric head CT examinations.

Bilateral medial frontal infarction in a case of azygous anterior cerebral artery stenosis.

We describe the unusual case of a 63-year-old woman with a history of arterial hypertension who presented a sudden weakness of the lower limbs followed by mutism, akinesia and dyspraxia. Magnetic resonance images showed a bilateral medial frontal infarction. Digital subtraction angiography documented a right azygous anterior cerebral artery with severe stenosis in its sub-callosal tract; the left anterior cerebral artery showed mild hypoplasia with only sub-frontal and fronto-polar branches. No embolic source was documented. Afterwards the patient presented a gradual and partial recovery of both motor and cognitive functions.

Reproducibility of BOLD localization of interictal activity in patients with focal epilepsy: intrasession and intersession comparisons.

ObjectSimultaneous EEG-fMRI recordings allow the identification of haemodynamic changes induced by neuronal activity during ictal or interictal epileptiform events (IEDs). We evaluated the reproducibility of continuous EEG-fMRI (cEEG-fMRI) in patients with focal epilepsy.Materials and methodsWe studied 15 patients with focal epilepsy (8 cryptogenic and 7 symptomatic) and frequent interictal abnormalities. Each patient underwent two cEEG-fMRI acquisitions (runs) in the same day (session) and 8 patients repeated the examination after one month. cEEG-fMRI reproducibility was defined by the existence of partially overlapping clusters between activation maps obtained from different runs.ResultsWe detected IEDs in 40 out of 46 EEG-fMRI runs and a related significant BOLD-response in all 40 runs. A prevalent positive BOLD response was detected in 12 patients and a prevalent negative response in 3 subjects. Statistical maps included a mean of 10 significant clusters. Nearly 30% of clusters were reproducible in both intrasession and intersession comparisons, with a mean overlap of 30%. Reproducibility did not differ between positive and negative BOLD-responses.DiscussionAmong the reproducible clusters, those with the highest percentage of overlap were concordant with the EEG electric field in all patients and they were localized in the same lobe as the brain lesion in patients with symptomatic epilepsy. We hypothesize that reproducible clusters could be more consistently related to the irritative zone than non-reproducible ones.ConclusionThe evaluation of cluster reproducibility could improve our knowledge of IED-related BOLD response. Moreover, it could enhance the reliability of cEEG-fMRI to identify the irritative zone in focal epileptic patients.

Primary angiitis of the central nervous system: Report of eight cases from a single Italian center

The primary angiitis of the central nervous system (PACNS) is a rare and potentially fatal form of vasculitis with unknown etiology. Headache and encephalopathy are the most frequent symptoms. Neuroimaging plays an important role in the diagnosis, but the pattern of abnormal findings is not specific. In some cases brain biopsy is mandatory. PACNS is often described as a diagnostic and therapeutic challenge for clinicians considering the lack of univocal diagnostic criteria and paucity of studies evaluating the long-term outcome. This brief work reports how we managed eight patients with PACNS from diagnosis to long-term follow up treatment. Headache and focal acute neurological deficits were the most common symptoms. Magnetic resonance imaging (MRI) was abnormal in all patients with different patterns of infarctions or intraparenchymal/subarachnoid hemorrhages or their combination. Cerebral angiography demonstrated pathological findings compatible with vasculitis in all cases. Other causes of encephalopathy were ruled out. Patients with severe clinical and neuroradiological findings were treated with steroids and immunosuppressive therapy using cyclophosphamide/methotrexate. Patients with less aggressive PACNS, were treated with steroids only. In one case with multiple relapses infliximab was used after first-line immunosuppressive therapy failure. PACNS suspicion is based on the combination of demographic/clinical and MRI findings and the exclusion of other causes of multifocal encephalopathy. A positive angiography has a diagnostic value in an adequate clinical field. A strict collaboration of neurologists, neuroradiologists, and immunoreumatologists is essential in the management of PACNS both in the diagnostic and therapeutic phases.