Modern imaging of the infarct core and the ischemic penumbra in acute stroke patients: CT versus MRI.

Thrombolysis has become an approved therapy for acute stroke. However, many stroke patients do not benefit from such treatment, since the presently used criteria are very restrictive, notably with respect to the accepted time window. Even so, a significant rate of intracranial hemorrhage still occurs. Conventional cerebral computed tomography (CT) without contrast has been proposed as a selection tool for acute stroke patients. However, more-modern MRI and CT techniques, referred to as diffusion- and perfusion-weighted imaging and perfusion-CT, have been introduced, which afford a comprehensive noninvasive survey of acute stroke patients as soon as their emergency admission, with accurate demonstration of the site of arterial occlusion and its hemodynamic and pathophysiological repercussions for the brain parenchyma. The objective of this article is to present the advantages and drawbacks of CT and MRI in the evaluation of acute stroke patients.

Multimodal CT in stroke imaging: new concepts.

A multimodal CT protocol provides a comprehensive noninvasive survey of acute stroke patients with accurate demonstration of the site of arterial occlusion and its hemodynamic tissue status. It combines widespread availability with the ability to provide functional characterization of cerebral ischemia, and could potentially allow more accurate selection of candidates for acute stroke reperfusion therapy. This article discusses the individual components of multimodal CT and addresses the potential role of a combined multimodal CT stroke protocol in acute stroke therapy.

18F-FDOPA PET/MRI fusion in patients with primary/recurrent gliomas: initial experience.

BACKGROUND AND PURPOSE: (18)F-FDOPA PET demonstrates higher sensitivity and specificity for gliomas than traditional [(18)F] FDG PET imaging. However, PET provides limited anatomic localization. The purpose of this study was to determine whether (18)F-FDOPA PET/MRI fusion can provide precise anatomic localization of abnormal tracer uptake and how this activity corresponds to MR signal abnormality. METHODS: Two groups of patients were analyzed. Group I consisted of 21 patients who underwent (18)F-FDOPA PET and MRI followed by craniotomy for tumor resection. Group II consisted of 70 patients with a pathological diagnosis of glioma that had (18)F-FDOPA PET and MRI but lacked additional pathologic follow-up. Fused (18)F-FDOPA PET and MRI images were analyzed for concordance and correlated with histopathologic data. RESULTS: Fusion technology facilitated precise anatomical localization of (18)F-FDOPA activity. In group I, all 21 cases showed pathology-confirmed tumor. Of these, (18)F-FDOPA scans were positive in 9/10 (90%) previously unresected tumors, and 11/11 (100%) of recurrent tumors. Of the 70 patients in group II, concordance between MRI and (18)F-FDOPA was found in 49/54 (90.1%) of patients with sufficient follow-up; in the remaining 16 patients concordance could not be determined due to lack of follow-up. (18)F-FDOPA labeling was comparable in both high- and low-grade gliomas and identified both enhancing and non-enhancing tumor equally well. In some cases, (18)F-FDOPA activity preceded tumor detection on MRI. CONCLUSION: (18)F-FDOPA PET/MRI fusion provides precise anatomic localization of tracer uptake and labels enhancing and non-enhancing tumor well. In a small minority of cases, (18)F-FDOPA activity may identify tumor not visible on MRI.

Prospective evaluation of multislice computed tomography versus plain radiographic cervical spine clearance in trauma patients.

BACKGROUND: The objective of this study was to compare the utility of plain radiographs to multislice computed tomography (MCT) for cervical spine (c-spine) evaluation. We hypothesized that plain radiographs add no clinically relevant diagnostic information to MCT in the screening evaluation of the c-spine of trauma patients. METHODS: This was a prospective, unblinded, consecutive series of injured patients requiring c-spine evaluation that were imaged with three-view plain films and MCT (occiput to T1 with 3-dimensional reconstruction). The final discharge diagnosis based on all prospectively collected clinical data, MCT, and plain films was utilized as the gold standard for the sensitivity calculation. RESULTS: From October 2004 to February 2005, 667 trauma patients requiring c-spine evaluation were enrolled. Average age was 35.4 years and 70% were male. The mechanism of injury was blunt in 99% and 48.7% occurred as a result of motor vehicle collision. Sixty of 667 (9%) sustained acute c-spine injuries. MCT had a sensitivity of 100% and specificity of 99.5%. Plain films had a sensitivity of 45% and specificity of 97.4%. Plain radiography missed 15 of 27 (55.5%) clinically significant c-spine injuries. CONCLUSION: MCT outperformed plain radiography as a screening modality for the identification of acute c-spine injury in trauma patients. All clinically significant injuries were detected by MCT. Plain films failed to identify 55.5% of clinically significant fractures identified by MCT and added no clinically relevant information.

Complications of cerebral arteriovenous malformation embolization: multivariate analysis of predictive factors.

OBJECTIVE: Embolization is an important therapeutic modality in the multidisciplinary management of arteriovenous malformations (AVM); however, prior series have reported a wide variability in overall complication rates caused by embolization (10-50% neurological deficit, 1-4% mortality). In this study, we reviewed our experience with AVM embolization and analyzed factors that might predict complications and clinical outcomes after AVM embolization. METHODS: We analyzed our combined neurovascular unit's results with AVM embolization from 1993 to 2004 for the following outcomes measures: 1) clinically significant complications, 2) technical complications without clinical sequelae, 3) discharge Glasgow Outcome Scale score, and 4) death. To determine embolization efficacy, we analyzed perioperative blood transfusion and rate of AVM obliteration. Univariate and multivariate analyses were performed for patient age, sex, history of rupture, history of seizure, associated aneurysms, AVM size, deep venous drainage, eloquent location, Spetzler-Martin grade, number of embolization stages, number of pedicles embolized, and primary treatment modality. RESULTS: Over an 11 year period, 295 embolization procedures (761 pedicles embolized) were performed in 168 patients with embolization as the primary treatment modality (n = 16) or as an adjunct to surgery (n = 124) or radiosurgery (n = 28). There were a total of 27 complications in this series, of which 11 were clinically significant (6.5% of patients, 3.7% per procedure), and 16 were technical complications (9.5% of patients, 5.4% per procedure). Excellent or good outcomes (Glasgow Outcome Scale > or = 4) were observed in 152 (90.5%) patients. Unfavorable outcomes (Glasgow Outcome Scale 1-3) as a direct result of embolization were both 3.0% at discharge and at follow-up, with a 1.2% embolization-related mortality. In the 124 surgical patients, 96.8% had complete AVM obliteration after initial resection, and 31% received perioperative transfusion (mean 1.4 units packed red blood cells per surgical patient). Predictors of unfavorable outcome caused by embolization by univariate analysis were deep venous drainage (P < 0.05), Spetzler-Martin Grade III to V (P < 0.05), and periprocedural hemorrhage (P < 0.0001) and by multivariate analysis were Spetzler-Martin III to V (odds ratio 10.6, P = 0.03) and periprocedural hemorrhage (odds ratio 17, P = 0.004). CONCLUSION: In a single-center, retrospective, nonrandomized study, 90.5% of patients had excellent or good outcomes after AVM embolization, with a complication rate lower than previously reported. Spetzler-Martin grade III to V and periprocedural hemorrhage were the most important predictive factors in determining outcome after embolization.

Safety of heparinization for cerebral aneurysm coiling soon after external ventriculostomy drain placement.

OBJECTIVE: Our practice has been to heparinize patients for cerebral aneurysm coiling even after recent external ventriculostomy drain (EVD) placement. The current medical literature cites a 12.5% symptomatic hemorrhage rate with heparinization after recent EVD placement. We reviewed our experience to determine our level of safety with this practice. METHODS: A search of our prospectively collected computerized aneurysm database revealed that from February 1998 to February 2004, 356 aneurysms were coiled, of which 119 patients had had recent EVD placement before coiling. During the same time period, 251 subarachnoid hemorrhage patients underwent EVD placement without coiling or heparinization. We reviewed the head computed tomographic scan reports and medical records to determine the incidence of EVD-related hemorrhage in heparinized patients compared with nonheparinized patients. RESULTS: There was only 1 patient in the heparinized group who had a symptomatic EVD-related hemorrhage attributable to heparinization (0.8%) and 11 patients with asymptomatic EVD-related hemorrhage (9.2%). Among the nonheparinized patients, there were 3 patients who had symptomatic EVD-related hemorrhages (1.2%) and 22 patients with asymptomatic EVD-related hemorrhages (8.8%) (P = not significant for both symptomatic and asymptomatic EVD-related hemorrhages). The time interval between EVD placement and heparinization in the heparinized patient with symptomatic EVD-related hemorrhage was 0.5 day; the mean time interval in the heparinized patients with asymptomatic EVD-related hemorrhage was 0.8 day; and in the heparinized patients with no hemorrhage, it was 0.8 day. The peak activated prothrombin time of the heparinized patient with symptomatic EVD-related hemorrhage was >150 seconds, the mean peak activated prothrombin time of the heparinized patients with asymptomatic EVD-related hemorrhage was 73.1 seconds, and that of the heparinized patients with no hemorrhage was 90.3 seconds. CONCLUSION: Heparinization for cerebral aneurysm coiling can be safely performed even after EVD placement within 24 hours, particularly if the activated prothrombin time is kept strictly controlled.