***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Introduction Since digital subtraction angiography ( DSA ) carries a low risk of morbidity , and is associated with patient discomfort and higher cost , our objective was to determine whether high-resolution 3-D time-of-flight MR angiography ( TOF-MRA ) at 3 T may replace DSA in the follow-up of patients after coiling of an intracranial aneurysm . Methods This prospect i ve study included 50 consecutive patients with a ruptured and subsequently coiled intracranial aneurysm . All patients were followed up at a mean of 14 months after coiling with DSA and high-resolution 3-D TOF-MRA at 3 T generating 0.02 mm3 isotropic voxels . One examiner used DSA and TOF-MR angiograms to assess the need for and risk of retreatment ; these data were used to calculate intermodality agreement . Another two examiners independently assessed aneurysm occlusion by DSA and TOF-MRA according to the Raymond scale ; these data were used to calculate interobserver agreement . Results Discrepancies between DSA and TOF-MRA were found in three patients ( intermodality agreement κ = 0.86 ) . While DSA indicated complete aneurysm occlusion , TOF-MRA showed small neck remnants in the three patients . Coils on all DSA projections obscured these three neck remnants . Interobserver agreement was higher for DSA ( κ = 0.82 ) than for TOF-MRA ( κ = 0.68 ) , which was in part due to the complexity of the information provided by TOF source images and reconstructions . Conclusion 3-D TOF-MRA at 3 T is not only an adjunctive tool but is ready to replace DSA in the follow-up of patients with previously coiled intracranial aneurysms . Additional DSA may only be performed in complex and not clearly laid out aneurysms BACKGROUND AND PURPOSE Digital subtraction angiography ( DSA ) is used to follow-up intracranial aneurysms treated with detachable coils to identify recurrence and determine need for additional treatment . However , DSA is invasive and involves a small risk of neurologic complications . We assessed the feasibility and usefulness of 3D time-of-flight ( TOF ) MR angiography ( MRA ) performed at 3 T compared with DSA for the follow-up of coil-treated intracranial aneurysms . METHODS In a prospect i ve study , 20 consecutive patients with 21 intracranial aneurysms treated with coils underwent DSA and nonenhanced and enhanced multiple overlapping thin-slab acquisition 3D TOF MRA at 3 T on the same day at a mean follow-up of 6 months ( range , 4 - 14 months ) after coil placement . MRA images were evaluated for presence of artifacts , presence and size of aneurysm remnants and recurrences , patency of parent and branch vessels , and added value of contrast material enhancement . MRA and DSA findings were compared . RESULTS Interobserver agreement of MRA was good , as was agreement between MRA and DSA . All three recurrences that needed additional treatment were detected with MRA . Minor disagreement occurred in four cases : three coil-treated aneurysms were scored on MRA images as having a small remnant , whereas on DSA images these aneurysms were occluded ; the other aneurysm was scored on MRA images as having a small remnant , whereas on DSA images this was a small recurrence . Use of contrast material had no additional value . Coil-related MR imaging artifacts were minimal and did not interfere with evaluation of the occlusion status of the aneurysm . CONCLUSION High-spatial-resolution 3D TOF MRA at 3 T is feasible and useful in the follow-up of patients with intracranial aneurysms treated with coil placement Background and Purpose — The purpose of this study was to estimate the performance measures of MR angiography ( MRA ) in the diagnosis of aneurysm residual flow after coil occlusion . Methods — Patients having at least 1 cerebral aneurysm treated with coil occlusion were prospect ively and consecutively enrolled . Time of flight and contrast-enhanced MRA were performed the same day of the DSA follow-up . The degree of aneurysm occlusion and dimensions of the residual flow were evaluated by independent readers at MRA and digital subtraction angiogram . MRA performance measures were estimated in a cross-sectional analysis and repeated in subgroups of aneurysm sizes and locations . MRA predictive values for recurrence were also estimated using a longitudinal design . Results — We obtained 167 aneurysm evaluations for each imaging modality . Class 3 residual flow was seen on digital subtraction angiogram follow-up in 27 % . The sensitivity and specificity of MRA was 88 % ( 95 % CI , 80–94 ) and 79 % ( 95 % CI , 67–88 ) , respectively . The positive predictive value for a Class 3 recurrence was 67 % ( 95 % CI , 51–80 ) and the negative predictive value was 93 % ( 95 % CI , 86–97 ) . Time-of-flight MRA underestimated the length of the residual flow ( P=0.039 ) , whereas contrast-enhanced MRA overestimated its width ( P<0.0001 ) . MRA sensitivity for a Class 3 residual flow was lower for aneurysms < 6 mm ( P=0.01 ) . Conclusions — MRA has sufficient accuracy for screening of aneurysm residual flow after coil occlusion . Due to its lower negative predictive value , recurrent aneurysms should be confirmed with digital subtraction angiogram before planning a retreatment . Routine use of MRA to follow small aneurysms should wait better estimation of its performance in this particular subgroup Background and Purpose — We sought to better define the morbidity of endovascular Guglielmi detachable coil ( GDC ) treatment of unruptured cerebral aneurysms and to discuss its role in the prevention of subarachnoid hemorrhage . Methods — We conducted an observational study from August 1992 to June 1999 of 125 unruptured aneurysms treated with GDC in 116 patients : 91 women ( 78.4 % ) and 25 men ( 21.6 % ) , aged 30 to 78 years ( mean age , 50.6 years ) . Immediate and late clinical results were recorded for any neurological event or hemorrhage related to the treated unruptured aneurysm . Angiographic results are reported as immediate , early ( 2 to 12 months ) , intermediate ( 12 to 30 months ) , and late follow-up ( > 30 months ) . Results — Immediate angiographic results showed complete obliteration ( class 1 ) in 59 ( 47.2 % ) or residual neck ( class 2 ) in 53 aneurysms ( 42.4 % ) , leaving 6 residual aneurysms ( 4.8 % ) and 7 failures ( 5.6 % ) . Early follow-up angiograms , available in 100 treated aneurysms ( 84 % ) , revealed class 1 in 52 % and class 2 in 41 % . Intermediate angiograms , available in 53 aneurysms ( 44.5 % ) , showed class 1 in 47.2 % and class 2 in 43.4 % , while late results , available in 37 lesions ( 31.1 % ) , had class 1 and 2 in 48.6 % and 37.8 % , respectively . Six patients suffered a permanent neurological deficit at last follow-up ( 5.2 % ) , with a good outcome in 5 patients and fair outcome in 1 patient . There was no mortality . There was no aneurysmal rupture during a mean clinical follow-up of 32.1 months . Conclusions — Endovascular treatment with GDC for unruptured aneurysms is relatively safe . Its role in the prevention of aneurysmal rupture remains to be determined , preferably by a r and omized study BACKGROUND AND PURPOSE : Blood-pool agents are promising in the imaging of small vessels with slow or complex flow . Our aim was to compare blood-pool contrast-enhanced MR angiography ( BPCE-MRA ) using gadofosveset trisodium ( Vasovist ) with 3D time-of-flight MRA ( TOF-MRA ) in the follow-up of intracranial aneurysms after endovascular therapy . MATERIAL S AND METHODS : We included 32 patients with a total of 37 coiled aneurysms . MRAs in the early steady-state phase were performed on a 1.5 T scanner within 8 days of digital subtraction angiography ( DSA ) . Two radiologists independently analyzed TOF-MRA and BPCE-MRA images . Consensus was reached by review involving a third neuroradiologist . DSA images were interpreted separately by an interventional radiologist . Findings were assigned to 1 of 3 categories : 1 ) complete occlusion , 2 ) residual neck , and 3 ) residual aneurysm . RESULTS : Follow-up DSA demonstrated 13 complete obliterations ( class 1 ) , 13 residual necks ( class 2 ) , and 11 residual aneurysms ( class 3 ) . Weighted κ statistics showed substantial concordance of TOF-MRA and DSA ( 0.664 ) as well as BPCE-MRA and DSA ( 0.724 ) ratings . Comparison between TOF-MRA and BPCE-MRA found excellent agreement ( 0.818 ) with only 6 ( 16.2 % ) discrepancies . For detecting residual flow , the difference in accuracy of both MRA techniques ( 83.8 % versus 91.9 % ) was not significant ( McNemar , P = 1.000 ) . BPCE-MRA showed a tendency towards higher sensitivity and specificity ( 91.7 % and 92.3 % , respectively ) compared with TOF-MRA ( 87.5 % and 76.9 % ) . CONCLUSIONS : In classifying the completeness of endovascular cerebral aneurysm therapy , we found that BPCE-MRA and 3D TOF-MRA showed very good agreement . The use of Vasovist did not lead to a significantly increased accuracy of MRA follow-up BACKGROUND AND PURPOSE : MR angiography ( MRA ) is increasingly used as a noninvasive imaging technique for the follow-up of coiled intracranial aneurysms . However , the need for contrast enhancement has not yet been eluci date d. We compared 3D time-of-flight MRA ( TOF-MRA ) and contrast-enhanced MRA ( CE-MRA ) at 3 T with catheter angiography . MATERIAL S AND METHODS : Sixty-seven patients with 72 aneurysms underwent TOF-MRA , CE-MRA , and catheter-angiography 6 months after coiling .  Occlusion status on MRA was classified as adequate ( complete and neck remnant ) or incomplete by 2 independent observers . For TOF-MRA and CE-MRA , interobserver agreement , intermodality agreement , and correlation with angiography were assessed by κ statistics . RESULTS : Catheter-angiography revealed incomplete occlusion in 12 ( 17 % ) of the 69 aneurysms ; 3 aneurysms were excluded due to MR imaging artifacts . Interobserver agreement was good for CE-MRA ( κ = 0.77 ; 95 % confidence interval [ CI ] , 0.55–0.98 ) and very good for TOF-MRA ( κ = 0.89 ; 95 % CI , 0.75–1.00 ) . Correlation of TOF-MRA and CE-MRA with angiography was good . The sensitivity of TOF-MRA and CE-MRA was 75 % ( 95 % CI , 43%–95 % ) ; the specificity of TOF-MRA was 98 % ( 95 % CI , 91%–100 % ) and of CE-MRA , 97 % ( 95 % CI , 88%–100 % ) . All 5 incompletely occluded aneurysms , which were additionally treated , were correctly identified with both MRA techniques . Areas under the receiver operating characteristic curve for TOF-MRA and CE-MRA were 0.90 ( 95 % CI , 0.79–1.00 ) and 0.91 ( 95 % CI , 0.79–1.00 ) . Intermodality agreement between TOF-MRA and CE-MRA was very good ( κ = 0.83 ; 95 % CI , 0.65–1.00 ) , with full agreement in 66 ( 96 % ) of the 69 aneurysms . CONCLUSIONS : In this study , TOF-MRA and CE-MRA at 3 T were equivalent in evaluating the occlusion status of intracranial aneurysms after coiling . Because TOF-MRA does not involve contrast administration , this method is preferred over CE-MRA In the GRADE approach , r and omized trials start as high- quality evidence and observational studies as low- quality evidence , but both can be rated down if most of the relevant evidence comes from studies that suffer from a high risk of bias . Well-established limitations of r and omized trials include failure to conceal allocation , failure to blind , loss to follow-up , and failure to appropriately consider the intention-to-treat principle . More recently recognized limitations include stopping early for apparent benefit and selective reporting of outcomes according to the results . Key limitations of observational studies include use of inappropriate controls and failure to adequately adjust for prognostic im 
    Output:
    
Both TOF-MRA and contrast-enhanced MRA are shown to be highly accurate for detection of any recanalization in intracranial aneurysms treated with endovascular coil occlusion