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The composition and source of brain emboli during cardiac surgery
scribed around the abnormal metabolites in the stroke hemisphere and mirrored to the contralateral hemisphere to measure t h e s u m of abnormal metabolites in white matter. Results: The table s h o w s the SPECT defect volume size and the corresponding abnormal metabolites. In all patients the stroke hemisphere had greater Ch/NA and Cr/NA abnormalities compared to the uninvolved hemisphere. C o n c l u s i o n : Distant cerebral abnormalities caused by diaschisis from stroke can be quantified using rCBF brain SPECT and high field 1H spectroscopic imaging. The direct results of axonal m e m b r a n e undercutting is best reflected as a decrease in Cr relative to Ch indicating there is m e m b r a n e integrity loss and lower metabolism in diaschisis. L e a r n i n g O b j e c t i v e s : l . The attendees should be able to list two mechanisms of stroke recovery. 2. The attendees should be able to list three important 1H spectroscopic metabolites in the brain.
4-25 Neuroimaging Findings in Cardiac Transplant Recipients Esat I. Memisoglu, MD, Temple University Hospital, Philadelphia, PA Borislav Nikolov, MD, Naveed Akhtar, MD, Jeffrey Greenstein, MD, Orest B. Boyko, MD, PhD P u r p o s e : To evaluate the neuroimaging brain findings in cardiac transplant patients and to explore the need to design a prospective study. M a t e r i a l s a n d M e t h o d s : W e retrospectively analyzed the medical records of 340 patients w h o u n d e r w e n t orthotopic cardiac transplantation b e t w e e n January 1993 and April 1997 at our institution. Crauial CT and/or MRI were obtained in 130 patients (Pre-transplant N=48, Mean age=52 and post-transplant N=82, Mean age=53) for evaluation of various neurological symptoms. Post-transplant imaging was performed at a m e a n of 14 m o n t h s aft~lrf,~l~ery. Results: Mild to m o d e r a t e ! ~ l l ~ l ~ r~']!ed in 16 (33%) pre and 21 (26%) p ~ s t ~ l a ~ ~ d l ~ ' ~ ' . ~ r g e vessel stroke was noted in 13 (27%) pre~ltl~l 1~1~'26%) post transplant patients. Periventricular white matter disease was noted in 8(17%) pre and 31 (38%) post transplant patients. Other less c o m m o n abnormalities were found in 8 (17%) pre and 12 (15%) post transplant patients. Conclusion: A high incidence of large vessel stroke is noted with no significantly increased stroke risk after transplantation. There is a greater incidence of periventricular white matter disease in the post transplant group w h i c h m a y be related to immtmosuppressive medications and or cerebrovaseular autoregulation. Significant cerebral atrophy was identified in b o t h groups with similar incidence and degree of atrophy indicating stability of brain volume. No infectious complication was identified. These findings suggest a favorable post transplant neurological course. Systematic and prospective studies are necessary for further evaluation of the neurological processes in cardiac transplant recipients. L e a r n i n g Objectives: 1. Identify t h e cerebral imaging findings after cardiac transplantation. 2. Understand the need to design a prospective study.
4-26 The Composition and Source of Brain Emboli During Cardiac Surgery Dixon M. Moody, MD, Bowman Gray School of Medicine, WinstonSalem, NC, Robert F. Brooker, MD, William R. Brown, PhD, Hani S. Ghazi-Birry, MD, DPhil, David A. Stump, PhD, J o h n W. Hammon, MD, et al P u r p o s e : To investigate the etiology of the p e r m a n e n t cognitive dec rement found in 16-38% of patients following cardiac surgery supported by cardiopulmonary bypass (CPB). M a t e r i a l s a n d M e t h o d s : Brains from patients (n=36) w h o died within four days of CPB and patients without CPB (n=40) were analyzed by alkaline phosphatase enzyme histochemistry w h i c h stains afferent, but not efferent microvessels. Brains were also examined with
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laser-activated microprobe mass spectrometry analysis (LAMMA) to detect the presence of metal poisoning. Results: Millions of lipid microemboli presenting as small capillary/arteriolar dilatations (SCADs), ranging in size from 10 to 50 # m were found in all CPB subjects and not in those without CPB. LAMMA on h u m a n s (n=6) detected a 5-40 increased concentration of aluminum and silicon in SCADs and surrounding neuropll. In dogs (n=13), using the exact CPB apparatus employed in humans, w e found 10 times the n u m b e r of SCADs in brain arterioles (p <.005) of animals in w h i c h shed blood from the thoracic cavity was returned to the circuit via suction and filtration t h r o u g h the cardiotomy reservoir. C o n c l u s i o n : Most lipid microemboli occurring during CPB can be traced to cardiotomy suction. Furthermore, they contain large quantifies of AI and Si. L e a r n i n g Objectives: T h e s e experiments present n e w information in the etiology of brain complications of heart surgery.
4-27 High-Resolution T2.Weighted Fast Spin-Echo MRI of the Pituitary: Comparison with Tl-Weighted Imaging without and with Contrast Leo J. Wolansky, MD, UMDNJ/NewJersey Medical School, Newark, NJ, Jamb Ibrahim, Huey-Jen Lee, MD, Satyaveni B. Rao, MD, Robert Brautigan, MD P u r p o s e : To compare high-resolution (512 " 256) T2-weighted fast spin-echo (T2-FSE) vs. Tl-weighted MRI with gadolinimn (Gd-T1) and without gadolinium (Plain-T1) in evaluating the pituitary gland. M a t e r i a l s a n d M e t h o d s : 50 consecutive patients had coronal and sagittal MRI scans of the pituitary gland including high-resolution T2weighted fast spin-echo, non-contrast Tl-weighted images, and gadolimum-enhanced Tl-weighted images. Blinded readings were performed by two readers. Results: All sequences demonstrated comparable specificities: T2FSE: 88%, T1-Gd: 86.8%; plain-Tl: 86.5%. The most sensitive sequence was Gd-TI: 76.4%, followed by T2-FSE: 76.4%, and plain-Tl: 60.6%. Positive predictive value was highest for T2-FSE (80.9%). Negative predictive value was highest for Gd-T1 (85.9%). C o n c l u s i o n s : While contrast-enhanced MRI had the highest sensitivity of all, T2-FSE was substantially m o r e sensitive than plain-T1. For non-contrast imaging of the pituitary, T2-FSE appears to be a valuable sequence, possibly superior to plain-T1. L e a r n i n g Objective: High-resolution T2-FSE of the pituitary can be performed rapidly (2 minutes and 12 seconds) and appears to be valuable in pituitary imaging.
4-28 Intracranial Gadolinium Enhanced FLAIR Imaging Esat I. Memisoglu, MD, Temple University Hospital, Philadelphia, PA Jaya Nath, MD, Naveed Akhtar, MD, Orest B. Boyko, MD, PhD P u r p o s e : To evaluate the appearance of the normal and abnormal gadolininm e n h a n c e d patterns of the brain on fast fluid inversion recovery (FLAIR) images and to determine the clinical utility of post contrast FLAIR imaging. M a t e r i a l s a n d M e t h o d s : W e report our experience with gadollniuni e n h a n c e d FLAIR on 723 patients obtained in the last 18 m o n t h s at our institution. Pre and post contrast FLAIR sequences were compared to post contrast T1 weighted imaging. In vitro imaging of serially diluted gadolinium in test tubes was performed to further define the normal signal intensity of contrast on FLAIR. Results: Post contrast FLAIR images were without hyperintense signal in major venous sinuses with less pulsatile flow artifacts. Cortical veins demonstrated flow void on post contrast FLAIR although enh a n c e m e n t was noted on spin echo imaging making the distinction of slow flow veins from leptomeningeal e n h a n c e m e n t more conspicuous. C o n c l u s i o n : Post contrast FLAIR imaging has an important role in evaluation of patients with leptomeningeal disease based on the supe-
4-25 Neuroimaging Findings in Cardiac Transplant Recipients Esat I. Memisoglu, MD, Temple University Hospital, Philadelphia, PA Borislav Nikolov, MD, Naveed Akhtar, MD, Jeffrey Greenstein, MD, Orest B. Boyko, MD, PhD P u r p o s e : To evaluate the neuroimaging brain findings in cardiac transplant patients and to explore the need to design a prospective study. M a t e r i a l s a n d M e t h o d s : W e retrospectively analyzed the medical records of 340 patients w h o u n d e r w e n t orthotopic cardiac transplantation b e t w e e n January 1993 and April 1997 at our institution. Crauial CT and/or MRI were obtained in 130 patients (Pre-transplant N=48, Mean age=52 and post-transplant N=82, Mean age=53) for evaluation of various neurological symptoms. Post-transplant imaging was performed at a m e a n of 14 m o n t h s aft~lrf,~l~ery. Results: Mild to m o d e r a t e ! ~ l l ~ l ~ r~']!ed in 16 (33%) pre and 21 (26%) p ~ s t ~ l a ~ ~ d l ~ ' ~ ' . ~ r g e vessel stroke was noted in 13 (27%) pre~ltl~l 1~1~'26%) post transplant patients. Periventricular white matter disease was noted in 8(17%) pre and 31 (38%) post transplant patients. Other less c o m m o n abnormalities were found in 8 (17%) pre and 12 (15%) post transplant patients. Conclusion: A high incidence of large vessel stroke is noted with no significantly increased stroke risk after transplantation. There is a greater incidence of periventricular white matter disease in the post transplant group w h i c h m a y be related to immtmosuppressive medications and or cerebrovaseular autoregulation. Significant cerebral atrophy was identified in b o t h groups with similar incidence and degree of atrophy indicating stability of brain volume. No infectious complication was identified. These findings suggest a favorable post transplant neurological course. Systematic and prospective studies are necessary for further evaluation of the neurological processes in cardiac transplant recipients. L e a r n i n g Objectives: 1. Identify t h e cerebral imaging findings after cardiac transplantation. 2. Understand the need to design a prospective study.
4-26 The Composition and Source of Brain Emboli During Cardiac Surgery Dixon M. Moody, MD, Bowman Gray School of Medicine, WinstonSalem, NC, Robert F. Brooker, MD, William R. Brown, PhD, Hani S. Ghazi-Birry, MD, DPhil, David A. Stump, PhD, J o h n W. Hammon, MD, et al P u r p o s e : To investigate the etiology of the p e r m a n e n t cognitive dec rement found in 16-38% of patients following cardiac surgery supported by cardiopulmonary bypass (CPB). M a t e r i a l s a n d M e t h o d s : Brains from patients (n=36) w h o died within four days of CPB and patients without CPB (n=40) were analyzed by alkaline phosphatase enzyme histochemistry w h i c h stains afferent, but not efferent microvessels. Brains were also examined with
748
laser-activated microprobe mass spectrometry analysis (LAMMA) to detect the presence of metal poisoning. Results: Millions of lipid microemboli presenting as small capillary/arteriolar dilatations (SCADs), ranging in size from 10 to 50 # m were found in all CPB subjects and not in those without CPB. LAMMA on h u m a n s (n=6) detected a 5-40 increased concentration of aluminum and silicon in SCADs and surrounding neuropll. In dogs (n=13), using the exact CPB apparatus employed in humans, w e found 10 times the n u m b e r of SCADs in brain arterioles (p <.005) of animals in w h i c h shed blood from the thoracic cavity was returned to the circuit via suction and filtration t h r o u g h the cardiotomy reservoir. C o n c l u s i o n : Most lipid microemboli occurring during CPB can be traced to cardiotomy suction. Furthermore, they contain large quantifies of AI and Si. L e a r n i n g Objectives: T h e s e experiments present n e w information in the etiology of brain complications of heart surgery.
4-27 High-Resolution T2.Weighted Fast Spin-Echo MRI of the Pituitary: Comparison with Tl-Weighted Imaging without and with Contrast Leo J. Wolansky, MD, UMDNJ/NewJersey Medical School, Newark, NJ, Jamb Ibrahim, Huey-Jen Lee, MD, Satyaveni B. Rao, MD, Robert Brautigan, MD P u r p o s e : To compare high-resolution (512 " 256) T2-weighted fast spin-echo (T2-FSE) vs. Tl-weighted MRI with gadolinimn (Gd-T1) and without gadolinium (Plain-T1) in evaluating the pituitary gland. M a t e r i a l s a n d M e t h o d s : 50 consecutive patients had coronal and sagittal MRI scans of the pituitary gland including high-resolution T2weighted fast spin-echo, non-contrast Tl-weighted images, and gadolimum-enhanced Tl-weighted images. Blinded readings were performed by two readers. Results: All sequences demonstrated comparable specificities: T2FSE: 88%, T1-Gd: 86.8%; plain-Tl: 86.5%. The most sensitive sequence was Gd-TI: 76.4%, followed by T2-FSE: 76.4%, and plain-Tl: 60.6%. Positive predictive value was highest for T2-FSE (80.9%). Negative predictive value was highest for Gd-T1 (85.9%). C o n c l u s i o n s : While contrast-enhanced MRI had the highest sensitivity of all, T2-FSE was substantially m o r e sensitive than plain-T1. For non-contrast imaging of the pituitary, T2-FSE appears to be a valuable sequence, possibly superior to plain-T1. L e a r n i n g Objective: High-resolution T2-FSE of the pituitary can be performed rapidly (2 minutes and 12 seconds) and appears to be valuable in pituitary imaging.
4-28 Intracranial Gadolinium Enhanced FLAIR Imaging Esat I. Memisoglu, MD, Temple University Hospital, Philadelphia, PA Jaya Nath, MD, Naveed Akhtar, MD, Orest B. Boyko, MD, PhD P u r p o s e : To evaluate the appearance of the normal and abnormal gadolininm e n h a n c e d patterns of the brain on fast fluid inversion recovery (FLAIR) images and to determine the clinical utility of post contrast FLAIR imaging. M a t e r i a l s a n d M e t h o d s : W e report our experience with gadollniuni e n h a n c e d FLAIR on 723 patients obtained in the last 18 m o n t h s at our institution. Pre and post contrast FLAIR sequences were compared to post contrast T1 weighted imaging. In vitro imaging of serially diluted gadolinium in test tubes was performed to further define the normal signal intensity of contrast on FLAIR. Results: Post contrast FLAIR images were without hyperintense signal in major venous sinuses with less pulsatile flow artifacts. Cortical veins demonstrated flow void on post contrast FLAIR although enh a n c e m e n t was noted on spin echo imaging making the distinction of slow flow veins from leptomeningeal e n h a n c e m e n t more conspicuous. C o n c l u s i o n : Post contrast FLAIR imaging has an important role in evaluation of patients with leptomeningeal disease based on the supe-