Objective: Recent studies of the corpus callosum (CC) in HIV have demonstrated significant reductions in the overall volume as well as alterations in the diffusion characteristics for small discrete regions of interest (ROIs). The purpose of this study was to examine the relationship between the diffusion tensor imaging (DTI) scalar metrics for several functionally related areas of the midsagittal CC and cognition among a group of CD4 stratified HIV infected patients.

Participants and Methods: Participants included 23 well characterized HIV infected patients and 10 demographically matched controls. The HIV infected patients were divided into two groups according to CD4 cell (n=11,<350; n=12,>350) to examine the influence of disease burden. Patients and controls were administered a battery of neuropsychological tests and underwent MRI including DTI.

The midsagittal CC was partitioned into seven functionally relevant areas using the Witelson protocol. FA and MD in each of these areas was examined for alterations relative to measures of disease burden. The relationship between these scalar metrics and several cognitive domains was also examined.

Results: Results demonstrated a dose effect for scalar metrics according to disease status and CD4 count with the controls having the best FA/MD values, higher CD4 cell count patients having middle FA/MD values, and lower CD4 cell count patients having the worst FA/MD values. These differences were more pronounced in the anterior regions of the CC and were significant statistically when comparing controls and HIV infected patients. Trends toward significance were noted when comparing the two HIV groups with increased disease burden having the most effect on diffusion values. FA/MD values in the anterior portions of the CC demonstrated robust relationships with measures of motor speed, semantic fluency, and free memory recall.

Conclusions: This study demonstrated alterations in FA/MD of the midsagittal CC with the most alteration occurring in the anterior regions. Furthermore, these alterations are associated with cognitive deficits often observed in HIV infected patients. Combined, these findings demonstrate the utility of DTI when examining the CNS and cognitive effects of HIV.



Your abstract entitled "Altered Diffision Scalar Metrics in the Midsagittal Corpus Callosum are Associated with Cognition Among HIV Patients" has been submitted. Please keep this confirmation until you receive your disposition via email on or around November 13^th, 2006. New this year: edits to the abstract (other than designating a different category) may be made online after submission up until the deadline of 5:30 pm EDT, October 3^rd, 2006 (please note that you will not receive an updated confirmation email when making additional edits).
Abstract Number
	U-155

Young Investigator Award or International Scholarship
Young Investigator	No
International Scholar	No

Conflict of Interest
Conflict of Interest	No

Previously Presented or Published
Previously Presented or Published	No

Category and Keywords
Category	U. Novel Diagnostic Technologies and New Monitoring Tools
Keywords	Diffusion Tensor Imaging, Cognition

Authors and Affiliations
Authors and Affiliations	David Tate*^1,2, Robert Paul³, Kathryn Coop¹, Timothy Flanigan¹, Song Zhang⁴, David Laidlaw⁴, and Karen Tashima¹ Center for AIDS Research, The Miriam Hospital, Providence, RI USA¹~ Center for Neurological Imaging, Brigham and Women`s Hospital, Boston, MA USA²~ University of St. Louis, St. Louis, MO USA³~ and Brown University, Providence, RI USA⁴
Emails	David Tate (dftate@bwh.harvard.edu) Robert Paul (paulro@umsl.edu) Kathryn Coop (kcoop@lifespan.org) Timothy Flanigan (tflanigan@lifespan.org) Song Zhang (szhang@cse.msstate.edu) David Laidlaw (dhl@cs.brown.edu) Karen Tashima (ktashima@lifespan.org)

Abstract
Title	Altered Diffision Scalar Metrics in the Midsagittal Corpus Callosum are Associated with Cognition Among HIV Patients

Body
Objective: Recent studies of the corpus callosum (CC) in HIV have demonstrated significant reductions in the overall volume as well as alterations in the diffusion characteristics for small discrete regions of interest (ROIs). The purpose of this study was to examine the relationship between the diffusion tensor imaging (DTI) scalar metrics for several functionally related areas of the midsagittal CC and cognition among a group of CD4 stratified HIV infected patients. Participants and Methods: Participants included 23 well characterized HIV infected patients and 10 demographically matched controls. The HIV infected patients were divided into two groups according to CD4 cell (n=11,<350; n=12,>350) to examine the influence of disease burden. Patients and controls were administered a battery of neuropsychological tests and underwent MRI including DTI. The midsagittal CC was partitioned into seven functionally relevant areas using the Witelson protocol. FA and MD in each of these areas was examined for alterations relative to measures of disease burden. The relationship between these scalar metrics and several cognitive domains was also examined. Results: Results demonstrated a dose effect for scalar metrics according to disease status and CD4 count with the controls having the best FA/MD values, higher CD4 cell count patients having middle FA/MD values, and lower CD4 cell count patients having the worst FA/MD values. These differences were more pronounced in the anterior regions of the CC and were significant statistically when comparing controls and HIV infected patients. Trends toward significance were noted when comparing the two HIV groups with increased disease burden having the most effect on diffusion values. FA/MD values in the anterior portions of the CC demonstrated robust relationships with measures of motor speed, semantic fluency, and free memory recall. Conclusions: This study demonstrated alterations in FA/MD of the midsagittal CC with the most alteration occurring in the anterior regions. Furthermore, these alterations are associated with cognitive deficits often observed in HIV infected patients. Combined, these findings demonstrate the utility of DTI when examining the CNS and cognitive effects of HIV.

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