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ABSTRACT |
Monday, May 1, 1:30 PM-3:30 PM
Abstracts 054-065
Moderators: Matthew F. Omojola, MB, BS and Michelle A. Michel, MD
1:30 PM
054. Predication of Early Hemorrhagic Transformation After Acute Stroke Using Parenchymal Enhancement and Hyperintensity MCA Sign
Guo G.1,2*; Wu R.H.1,2*; terBrugge K.2; Mikulis D.J.2; 1. Department of Radiology, The Second Hospital, Shantou University Medical College, Shantou, Guangdong, China; 2. Department of Medical Imaging, The Toronto Western Hospital, University of Toronto, Toronto, ON, Canada.
Address correspondence to G. Guo (james_guo2002{at}yahoo.ca)
Objective: To investigate the parenchymal enhancement and hyperintensity MCA sign on Gd-DTPA enhanced MRI in acute ischemic stroke patients to determine their associations with subsequent hemorrhagic transformation.
Materials and Methods: Twenty-four patients with ischemic stroke who underwent MR imaging within 4.9 hours (±1.4) of symptom onset were retrospectively reviewed. All of these patients underwent repeat at least one follow-up MR or CT studyat 1 week subsequently. Initial MR images were analyzed for parenchymal enhancement and hyperintensity MCA sign on T1-weighted imaging after Gd-DTPA administration.
Results: Ten (41.67%) patients were developed subsequent HT at follow-up imaging. (hemorrhagic group). The parenchymal enhancement was found in 6 hemorrhagic patients (p < 0.05); hyperintensity MCA sign was obtained in 5 hemorrhagic patients (p < 0.05); Fourteen patients who not developed subsequent HT (nonhemorrhagic group) were vascular enhancement alone. None of patient in nonhemorrhagic group had parenchymal enhancement and/or hyperintensity MCA sign.
Conclusion: Early parenchymal enhancement of stroke lesions and the hyperintensity MCA sign on T1WI after Gd-DTPA administration may be predictors of subsequent HT may help identify patients at risk.
055. 4D Evaluation of Saccular Aneurysm Phantom Pulsation Using 64-MDCT and Electrocardiographic (ECG) Gating
Yaghmai V.*; Rohany M.; Shaibani A.; Goodwin L.; Radiology, Northwestern University-Feinberg School of Medicine, Chicago, IL.
Address correspondence to V. Yaghmai (v-yaghmai{at}northwestern.edu)
Objective: To demonstrate pulsatile motion of a saccular aneurysm phantom during systole and diastole using high-resolution helical CT angiography and retrospective ECG gating.
Materials and Methods: Two saccular aneurysm models were created. One had uniform wall thickness and another had variable wall thickness with non-uniform wall compliance. Both had a maximal diameter of less than 1cm in size. Pulsatile flow in the aneurysms was achieved by a bellow pump (Iwaki America, MA, USA). The phantoms were scanned using a 64-channel multi-slice CT (Sensation Cardiac 64, Siemens Medical Solutions). The aneurysms were filled with diluted iodinated contrast material (250 HU) and scanned during continuous pulsation with a gantry rotation time of 0.33sec and a pitch of 0.2. Data was acquired as the scanner generated an artificial ECG tracing. Images were reconstructed using 0.6 mm section thickness and a 0.4 mm overlap. Raw data was reconstructed at 10% intervals during the R-R interval (total of 10 phases) and 4D images were evaluated using cine-mode. To maintain image quality, ECG-controlled tube current modulation was not utilized. Images were evaluated on a Siemens Leonardo workstation. Acquired images were compared with the phantom motion.
Results: Using this technique, pulsatile motion of the aneurysm was imaged. Image acquisition took approximately 5 seconds. There was excellent correlation between the motion of the phantom and the acquired cine-images. Asymmetric wall motion was demonstrated in the aneurysm where there was variance in wall compliance.
Conclusion: 4D evaluation of saccular aneurysms can be achieved rapidly by a 64-MDCT. Furthermore, wall motion abnormality and asymmetric motion of the wall can be demonstrated using this technique. This may be helpful when evaluating for mechanism of aneurysm rupture and treatment planning.
056. Follow up of Patients with Unruptured Intracranial Aneurysms using Spiral Computerized Tomography Angiography (CTA).
Kang A.1; Ly S.1; Pisa M.2; Khalil T.1; Young N.1*; Dorsch N.3; 1. Radiology, Westmead Hospital, Sydney, NSW, Australia; 2. Centre for Health Services Research, Westmead Hospital, Sydney, NSW, Australia; 3. Neurosurgery, Westmead Hospital, Sydney, NSW, Australia.
Address correspondence to N. Young (rnyo{at}imag.wsahs.nsw.gov.au)
Objective: This is a study of one hundred and nineteen patients from 1997 to 2004, who have known unruptured intracranial aneurysms. The purpose of our study was to evaluate the indicators of growth and rupture of intracranial aneurysms in patients with computerized tomography angiography (CTA).
Materials and Methods: Patients were referred to the study by a neurosurgeon, neurologist or their general practitioner. All patients had spiral CT angiography on a single slice GE Hispeed unit and use of a 16 slice Toshiba unit from 2003. Images were reported on a Windows Workstation by a single radiologist.
Results: In total, there were 119 patients with 138 aneurysms. 41 patients (34.5%) were male and 78 patients (65.5%) were female. On initial CTA, 6 patients had 0 aneurysms (5%), 89 patients had 1 aneurysm (75%) and 24 patients had 2 aneurysms (20%). Of the 138 aneurysms, 120 were pre-existing and 18 de novo. 99 aneurysms were stable (71.8%), 29 aneurysms enlarged (21%), 1 aneurysm ruptured (0.7%) and 9 aneurysms decreased in size (6.5%). When considering size, aneurysms < 2 mm diameter: larger in 70% (12/17), aneurysms 2-6 mm diameter: larger in 13% (10/80), aneurysms 7-12 mm diameter: larger in 13% (4/31), rupture in 3.2% (1/31), aneurysms 13-24 mm diameter: larger in 30% (3/10). When considering aneurysm locations, AComm: larger in 17% (5/30), ICA: larger in 24% (7/29), MCA: larger in 16% (9/57), PComm: larger in 67% (2/3), Basilar: larger in 43% (6/14), Vertebrals: larger in 0% (0/3). 2 aneurysms in other locations were stable. 17/18 (94%) of the de novo aneurysms enlarged.
Conclusion: Spiral CTA is a useful tool in assessing patients with untreated intracranial aneurysms, to evaluate changes in size and the development of new aneurysms.
057. Absolute Quantification of Cerebral MR Perfusion: Serial Studies in Volunteers and Patients
Essig M.1*; Le Huu M.1; Moeller A.2; Kirchin M.3; Lodemann K.P.4; 1. Department of Radiology, German Cancer Research Center, Heidelberg, Germany; 2. Medical Imaging, Medical Imaging Heidelberg, Heidelberg, Germany; 3. Worldwide Medical Affairs, Bracco Imaging, Milan, Italy; 4. Clinical Department, Bracco Altana Pharma, Konstanz, Germany.
Address correspondence to M. Essig (m.essig{at}dkfz.de)
Objective: Perfusion MRI has proven useful for assessment of cerebrovascular diseases, brain tumors and dementia. For therapy monitoring an absolute or "semiabsolute" quantification is mandatory. Two crucial aspects of quantitative MR-perfusion are a robust and reliable arterial input function, and the amount of the relative signal reduction, which is the basis for the calculation of cerebral blood volume (CBV) and flow (CBF). Both requirements depend on the concentration and the T2-relaxivity of the contrast agents used. The present study evaluated the use of Gd-BOPTA (MultiHance, Bracco Diagnostics Inc.) for quantitative cerebral perfusion MRI.
Materials and Methods: A blinded randomized intra-individual comparative study was conducted in 12 healthy male volunteers and 30 patients with cerebral gliomas. Imaging parameters, slice positioning and contrast media application were standardized. Volunteers were examined with 0.1 and 0.2 mmol/kg, and patients with 0.1 mmol/kg Gd-BOPTA. For quantitative assessment, the percentage signal drop and the full width half maximum (FWHM) were assessed with ROIs placed in normal grey and white matter. The rCBV and rCBF values of gray and white matter were calculated and compared between the different imaging times. Two independent offsite readers evaluated image quality of the rCBV and rCBF maps with respect to grey and white matter and basal ganglia delineation.
Results: High quality MR perfusion maps were achieved with a single dose of Gd-BOPTA. The mean signal drop of 32% resulted in a good quality input function. Calculated rCBV and rCBF absolute values of the different ROIs were constant for both dosages within each subject, while differences between subjects were marginal. In the qualitative assessment, both readers found images after a 0.1 mmol/kg dose well suited for grey-white matter differentiation and the delineation of the basal ganglia. In the patient studies, all perfusion scans were of excellent diagnostic quality. Qualitative assessment suggested a clinical benefit from perfusion imaging with respect to lesion detection and delineation. In patients with glioma, differentiation between low grade and high grade tumors was possible.
Conclusion: Our results suggest that absolute quantification and high quality MR perfusion maps are possible with adequate software and the use of a higher relaxivity contrast agent. Intraindividual values were constant over time and interindividual differences were objective.
058. Intra-individual Crossover Comparison of Gadobenate Dimeglumine and Gadopentetate Dimeglumine in MRI of the Central Nervous System
Maravilla K.R.1*; Maldjian J.A.2; Schmalfuss I.M.3; Kuhn M.J.4; Bowen B.C.5; Wippold F.J.6; 2. Department of Radiology, University of Florida College of Medicine, Gainesville, FL; 1. Department of Radiology, University of Washington, Seattle, WA; 2. Department of Radiology, Wake Forest University, Winston-Salem, NC; 4. Department of Radiology, Southern Illinois University, Springfield, IL; 5. Department of Radiology, University of Miami, Miami, FL; 6. Department of Radiology, Washington University, St. Louis, MO.
Address correspondence to K.R. Maravilla (kmarav{at}u.washington.edu)
Objective: To compare safety and efficacy of 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA) and gadopentetate dimeglumine (Gd-DTPA) in MRI of lesions of thecentral nervous system (CNS) using a multicenter, double-blind, randomized, intra-individual, crossover design.
Materials and Methods: Patients referred for MRI of the CNS (n = 151) underwent two examinations at 1.5 T, one enhanced with 0.1 mmol/kg Gd-BOPTA and the other with 0.1 mmol/kg Gd-DTPA. Contrast injection was performed in blinded fashion and randomized order with 2-7 days between administrations. Imaging parameters and acquisition times were identical for the two examinations. Images were evaluated by three independent and blinded neuroradiologists in terms of diagnostic information (lesion border delineation, definition of disease extent, visualization of lesion internal morphology, lesion contrast enhancement, global diagnostic preference) and quantitative parameters (% lesion enhancement, contrast-to-noise ratio, CNR). Safety was assessed monitoring patients for adverse events (AE) for 24 hours after each injection.
Results: Readers 1, 2 and 3 demonstrated global diagnostic preference in 75, 89 and 103 patients, respectively, for Gd-BOPTA compared with only 7, 10 and 6 patients, respectively, for Gd-DTPA (p < 0.0001; all readers). Highly significant (p < 0.0001; all readers, all comparisons) superiority of Gd-BOPTA was demonstrated for all individual diagnostic information endpoints, for % lesion enhancement and for increased CNR. The AE rate was 9% with both agents. All AE were non-serious, and most were transient and self-resolving with both agents.
Conclusion: Gd-BOPTA provided significantly better contrast enhancement and diagnostic information compared to Gd-DTPA at equivalent dose. The two agents were equally safe and well tolerated.
059. Blinded Crossover Comparison of Gadobenate Dimeglumine and Gadopentetate Dimeglumine for Visualization and Assessment of Intra-axial Brain Tumors
Maldjian J.A.1*; Anzalone N.2; Schmalfuss I.M.3; Kremer S.4; Bowen B.C.5; Maravilla K.R.6; 1. Department of Radiology, Wake Forest University, Winston-Salem, NC; 2. Department of Neuroradiology, Hospital San Raffaele, Milan, Italy; 3. Department of Radiology, University of Florida, Gainesville, FL; 4. Department of Neuroradiology, University Hospital of Nancy, Nancy, France; 5. Division of Neuroradiology, University of Miami School of Medicine, Miami, FL; 6. Department of Radiology, University of Washington, Seattle, WA.
Address correspondence to J.A. Maldjian (maldjian{at}wfubmc.edu)
Objective: To compare the enhancement of intra-axial CNS lesions after 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA) and 0.1 mmol/kg gadopentetate dimeglumine (Gd-DTPA).
Materials and Methods: A multicenter, double-blind, randomized, crossover comparison was conducted in 92 patients with primary or secondary intra-axial brain tumors. Each patient underwent two MR examinations at 1.5 T, one with Gd-BOPTA and one with Gd-DTPA with 2-7 days between administrations. T1wSE and T2wFSE sequences were acquired pre-dose with post-dose repetition of the T1wSE sequence (performed at an identical post-dose acquisition time). Three fully blinded readers independently evaluated all images in terms of degree and quality of diagnostic information (lesion border delineation, definition of disease extent, visualization of lesion internal morphology, lesion contrast enhancement, global diagnostic preference) and quantitative parameters (% lesion enhancement, contrast-to-noise ratio). Differences were tested statistically with the Wilcoxon signed rank test. Reader agreement was assessed using weighted kappa statistics.
Results: All readers noted significantly (p < 0.0001) better diagnostic information and contrast enhancing performance for Gd-BOPTA for all lesion visualization endpoints and quantitative determinations. Readers 1, 2 and 3 considered contrast enhancement and diagnostic information to be superior in 48 (52%), 58 (63%) and 61 (66%) patients, respectively, after Gd-BOPTA compared with 4 (4%), 5 (5%) and 3 (3%) patients after Gd-DTPA (p < 0.0001). Similar differences were noted for all other determinations. Agreement between the three readers was good (kappa > 0.4, all determinations).
Conclusion: Gadobenate dimeglumine permits significantly improved enhancement of intra-axial CNS lesions, potentially enabling improved patient management and pre-surgical planning.
060. Iodine Contrast Material Dose Optimization for Multi-detector Row CT of Neck by Using Dual-phase Injection Technique (Work-in-Progress)
Namasivayam S.*; Kalra M.K.; Pottala K.; Hudgins P.; Radiology, Emory University Hospital, Atlanta, GA.
Objective: To compare arterial, venous and mucosal enhancement in MDCT of neck with 150, 100, and 75 ml of 350 mg I/mL contrast material, by using a dual-phase injection technique.
Materials and Methods: IRB approval was obtained. Two study cohorts of 26 consecutive subjects underwent MDCT of neck with a contrast material dose of 100 mL injected as 40 mL at 2 mL/second, and 60 mL at 3 mL/s (mean age, 49 years; M:F, 9:17) or 75 mL injected as 35 mL at 1.4 mL/s, and 40 mL at 3.5 mL/s (mean age, 52 years; M:F, 15:11). A control cohort of 26 subjects (mean age, 54 years; M: F, 12:14) received 150 mL injected as 100 mL at 2 mL/s, and 50 mL at 1 mL/s. Scan delay was 45 seconds for all groups. Fifteen additional subjects were scanned with 75 mL contrast and a 55-second-delay. Remaining scanning parameters were held constant. Scan duration was recorded. Two radiologists compared images of control and study cohorts for arterial, venous and mucosal enhancement, and overall image quality using a five-point scale (1-unacceptable, 5-excellent). In addition, CT attenuation measurements of common carotid artery (CCA), and internal jugular vein (IJV) were measured. Data were analyzed with student t test, and kruskal wallis test.
Results: Scan durations were comparable for the three groups (p = 0.21-0.74). There was no significant difference (p = 0.25-0.98) between the overall image quality of three study groups. Both radiologists reported acceptable enhancement in all subjects of 100 mL dose cohort. All patients of 150 mL dose cohort had acceptable arterial enhancement (scores 3). Four patients had unacceptable enhancement (venous, n = 2; mucosal, n = 2) with 150 mL dose cohort. All patients had acceptable arterial and venous enhancement with 75 mL. Ten patients had substandard mucosal enhancement with 75 mL. Enhancement of CCA (289.6 H±84.1) was significantly greater with 75 mL when compared to 100 mL (249.8 H±62.7), and 150 mL (212 H±55.6) (p = 0.029). Similarly, IJV enhancement with 75 mL (305.6 H±80.7) was greater than IJV enhancement with 100 mL (247.8 H±65.5), and 150 mL (192.9 H±58.2) (p = 0.003). All patients had acceptable mucosal enhancement in the 55-second-delay and 75 mL dose.
Conclusion: With dual-phase injection technique, 75 mL contrast material dose resulted in acceptable arterial and venous enhancement with MDCT of neck. Acceptable mucosal enhancement was also achieved when the delay was increased to 55 seconds. Study is in progress for further contrast material dose reduction to 50 mL.
061. Increases in Fractional Anisotropy Values in Normal Infants during the First Year of Life
Provenzale J.M.*; Liang L.; DeLong D.; White L.E.; Radiology, Occupational and Physical Therapy, Duke University Medical Center, Durham, NC.
Address correspondence to J.M. Provenzale (prove001{at}mc.duke.edu)
Objective: In previous work [1], developmental increases in FA in early childhood (ages 12-72 months) were greater in non-compact white matter compared to compact white matter. Our present purpose was to determine if this differential maturation is manifest in the first year of life. Our hypothesis was that fractional anisotropy (FA) values on diffusion tensor images increase at a greater rate in non-compact white matter (WM) regions relative to compact WM regions in the first year of life.
Materials and Methods: Fifty-four children (36 boys, 18 girls, mean age 5.3 months) under one year of age underwent conventional MR imaging and diffusion tensor imaging (DTI) with gradient encoding in 6 directions (b value of 1,000 s/mm2) on a 1.5 T MR scanner. FA values were measured in 3 compact WM structures (posterior limb of internal capsule, genu and splenium of corpus callosum) and 2 non-compact WM regions (frontal and parietal WM) by a single observer blinded to age using a standard region of interest of 44+4 mm2. Linear regression models for the FA values versus age were fit and found to be adequate. A MANOVA test was used to compare the average of the age regression coefficients for the compact WM structures to that of the non-compact WM structures.
Results: At birth, FA values in compact WM were nearly half their adult value, indicating significant structural maturation. In contrast, non-compact WM values at birth were barely discernible above noise. Despite these early differences, FA increased at nearly the same rate in both compact and non-compact WM increased FA throughout the first year of life. However, contrary to our hypothesis, the rate of increase was slightly greater for compact WM, with an advantage of 0.006 per month (SE 0.0016, p < 0.001).
Conclusion: Compact WM achieves higher FA earlier in brain development and continues to increase at a slightly greater rate in the first year than non-compact WM, although the rate of increase is slightly greater for non-compact WM in the ensuing 1-4 years [1]. Thus, the maturation of cerebral WM, assessed with DTI, is nonuniform among brain structures and across early postnatal development.
1. McGraw P, Liang L, Provenzale JM. Evaluation of normal age-related changes in anisotropy during childhood with diffusion-tensor imaging. AJR 2002; 179:1515-1522
062. AHA Type 6 Atherosclerotic Plaque Identified by MRI is Associated with Ipsilateral Acute and Hyperacute TIA/IS
Parmar J.P.*; Kramer C.M.; Mugler J.P.; Baskurt E.; Altes T.A.; Rogers W.J.; Department of Radiology, University of Virginia, Charlottesville, VA.
Address correspondence to J.P. Parmar (jp5ka{at}virginia.edu)
Objective: Atherosclerotic plaque rupture is thought to cause TIA and ischemic stroke (IS). Our aim was to examine the relationship between acute or hyperacute TIA/IS and AHA type VI atherosclerotic plaque.
Materials and Methods: Seventy-three consecutive patients referred for acute stroke protocol MRI/MRA examination underwent additional T1- and T2-weighted carotid bifurcation imaging using 3D variable excitation turbo spin echo black blood MRI imaging. Two blinded reviewers performed plaque gradings according to the MRI modified AHA system. Clinical outcome and brain MR results were obtained via chart review.
Results: Image quality for MR plaque characterization was adequate in 56/73 (77%) patients (30 male, mean age 64.3, SD 16.0). 26 patients had IS with acute/hyperacute brain MR diffusion abnormality, 14 patients had TIA diagnosis, and, 30 patients had no cerebral ischemia. Four TIA/IS patients had non carotid etiology for TIA/IS, yielding 52 patients: 104 paired watershed vessel/cerebral hemisphere observations. 16/104 (15%) demonstrated type VI plaque with ipsilateral TIA/IS. 66/104 (63%) demonstrated lesions other than type VI and had no ipsilateral TIA/IS. Positive predictive value of 59% and negative predictive value of 86% were observed. The association between plaque type VI and ipsilateral TIA/IS was significant, p < 0.001. No statistically significant association was observed between severe stenosis and outcome.
Conclusion: Type 6 carotid bifurcation region plaque identified by MRI was associated with ipsilateral acute TIA/IS, while stenosis was not. These findings suggest that TIA/IS etiology is more commonly associated with the type of underlying plaque rather than severe stenosis.
063. Comparison of High-spatial Resolution (HR) MRA at 3T with b-flow Ultrasound for the Grading of Carotid Artery Stenosis (CAS)
Michaely H.J.1*; Clevert D.A.1; Nael K.2; Kramer H.1; Reiser M.F.1; Schoenberg S.O.1; 1. Institute of Clinical Radiology, University of Munich, Grosshadern Campus, Munich, Germany; 2. Department of Cardiovascular Radiology, UCLA, Los Angeles, CA.
Address correspondence to H.J. Michaely (henrik.michaely{at}med.uni-muenchen.de)
Objective: To compare HR-MRA at 3T with state of the art ultrasound for the grading of CAS.
Materials and Methods: 12 patients (mean age 63.3 years) with ultrasound (GE Logiq 9) proven CAS underwent HR-MRA at 3T (Siemens Tim TRIO) using a fast elliptic-centric GRE-sequence (TR/TE - 3.14/1.04s, voxel size 0.7x0.7x0.8mm3, acquisition time 18s, parallel imaging acceleration factor 3) after the administration of 15ml Gd-BOPTA (Multihance, Bracco-Altana Pharma). The degree of stenosis was determined by two radiologists in consensus as area stenosis (cross sectional view) and diameter stenosis (coronal or sagittal view) on the MRA reconstructions. Reconstructions were always tilted to best follow the vessel or perpendicularly meet the vessel. For the ultrasound exam a 12MHz probe was utilized and b-flow, color-coded duplex ultrasound and power-Doppler were measured to assess the maximal systolic and enddiastolic velocity in the stenotic segment. Based on the peak systolic velocity CAS were graded as either low-grade (75%). Correlations were used for statistical analysis.
Results: All MR examinations were of diagnostic quality. The correlation between the MRA results and the US results was very good for high-grade CAS (r = 0.88, p = 0.001) for both diameter and area stenosis, while the correlation for low-grade and intermediate CAS was worse (r < 0.78, p = 0.02). The area stenosis hereby seemed to be superior.
Conclusion: HR-MRA at 3T seems to be as exact as state-of-the-art ultrasound for the grading of CAS even for filiform stenosis, particularly when the area stenosis is used.
064. How Effective is a 3D-Time-resolved Echo-shared Angiographic Technique (TREAT) in the Detection of Hemodynamically Significant Carotid Artery Stenosis?
Michaely H.J.*; Herrmann K.A.; Nael K.; Reiser M.F.; Schoenberg S.O.; Institute of Clinical Radiology, University of Munich - Grosshadern Campus, Munich, Germany.
Address correspondence to H.J. Michaely (henrik.michaely{at}med.uni-muenchen.de)
Objective: To evaluate the efficacy of TREAT in the detection of hemodynamically significant carotid artery stenosis (CAS) by assessment of flow delay.
Materials and Methods: 33 patients (15 female, 18 male, age 69.7 ± 9.2) with suspected CAS underwent high resolution (HR)-MRA of the supraaortic vessels. HR-MRA was performed on a 1.5T MR-system (Siemens Sonata) using a fast 3D-GRE sequence with parallel imaging (TR/ TE / Voxel size /iPAT factor - 3.76 ms/ 1.24 ms/ 0.9 x 0.7 x 0.9 mm3/2) and a bolus of 15 ml of gadobutrol. Time-resolved MRA was performed with a 3D-TREAT sequence (TR/ TE / Voxel size /iPAT factor - 2.29 ms/ 0.95 ms/ 2.0 x 1.4 x 2.0 mm3/ 2) acquiring 23 3D data sets, one every 2.3 s after the injection of a 10 ml bolus of gadobutrol. TREAT combines view-sharing techniques to undersample k-space together with parallel imaging techniques to maximize temporal and spatial resolution. The presence of CAS and the vessel area within and 2cm after the CAS was determined on multiplanar reconstructions. The degree of stenosis (%) was calculated as (1-(area of stenosis/reference area))*100 based on HR-MRA data as a reference. CAS > 75% were considered hemodynamically significant. For semiquantitative assessment of flow changes, signal-intensity over time curves (SIVTC) were generated from TREAT data using commercially available software (Mean Curve, Siemens). Regions of interest were placed in both common and internal carotid arteries. SIVTCs in the common carotid arteries served as reference for the determination of delayed flow in the stenotic vessel. T-tests were performed for statistical analysis.
Results: All TREAT measurements were diagnostic. No CAS was present in 8 patients, 11 patients had CAS < 75% and 13 patients had CAS > 75%. In patients without CAS, no flow delay was found. Flow delay was identified in 2/11 patients with CAS < 75% (18.2%) and in 11/14 patients (78.5%, p = 0.014) with CAS > 75%. Mean flow delay with CAS < 75% was 0.3 frames whereas with CAS > 75% the mean flow delay was 1.6 frames.
Conclusion: TREAT is an easily applicable and effective tool to monitor flow delay in stenotic carotid arteries. The identification of flow delay on TREAT imaging is highly indicative of a hemodynamically significant CAS.
065. 64-MDCT Angiography in the Assessment of ICA Stenosis: Comparison with Color Doppler, Power Doppler and B-flow Ultrasound
Clevert D.A.1*; Stickel M.2; Michaely H.1; Stautz P.1; Flach P.1; Becker C.1; Jung E.M.3; Reiser M.1; 1. Department of Clinical Radiology, University of Munich-Grosshadern, Munich, Germany; 2. Department of Surgery, University of Munich-Grosshadern, Munich, Germany; 3. Department of Clinical Radiology, Passau, Passau, Germany.
Address correspondence to D.A. Clevert (Clevert{at}web.de)
Objective: To compare the diagnostic accuracy of 64-slice multislice CT angiography (64-MDCTA) and color doppler (CD), power doppler (PD) and B-flow ultrasound in the grading of extracranial high degree internal carotid artery (ICA) stenosis.
Materials and Methods: 37 patients with 43 known or suspected ICA-stenoses underwent MDCTA (Somatom Sensation 64, Siemens Medical Systems, Forchheim, Germany). Collimation was 64x0.6 mm, rotation time 0.33 s, Pitch 1, slice thickness 0.75 mm, reconstruction interval 0.5 mm. 120 ml Solutrast 300 (Bracco) were injected at a flow rate of 5 ml/s, followed by 50 ml saline. Bolus tracking was used. CT angiograms were analyzed for caliber irregularities, presence of intravascular thrombus, and presence of calcified plaques. In color doppler sonography, power doppler and B-Flow (Logiq 9, GE Healthcare, Milwaukee, WI), the degree of stenosis (NASCET-criteria), the maximum peak systolic velocity at the stenotic site and the poststenotic flow parameters were evaluated. The results were correlated with CTA, CD, PD and B-Flow, the intraoperative findings and clinical follow-up.
Results: Using the 64-MDCTA, excellent visualization of vessels was achieved in all cases. 28/43 had stenoses between 70-80%, 10/43 had stenoses between 80-90% and were correctly detected in CTA and CD/PD/B-flow. Filiform ICA stenoses were seen with CD in 3, PD in 4 and with B-Flow in 5 cases. In 3 cases of filiform ICA stenoses, CTA overrated the degree of stenosis in the presence of extensive calcified plaques. In these cases, no residual lumen could be detected at MDCTA. Intraoperative findings in these cases showed filiform stenoses.
Conclusion: 64-MDCTA is highly accurate in the detection and grading of ICA stenoses between 70-90%. There is an excellent correlation with CD, PD and B-flow ultrasound. In cases of filiform stenoses and extensive calcified plaques, MDCTA may overrate the grade of stenosis. In these cases, ultrasound was more accurate in detection of a residual lumen. Duplex sonography is useful for screening purposes.
* Will present paper
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