F A Jolesz

Publications of F A Jolesz

• Image-guided neurosurgery at Brigham and Women's Hospital

  Authors: S.P. Dimaio, N. Archip, N. Hata, I.-F. Talos, S.K. Warfield, A. Majumdar, N. McDannold, K. Hynynen, P.R. Morrison, W.M.I.I.I. Wells, D.F. Kacher, R.E. Ellis, A.J. Golby, P.M. Black, F.A. Jolesz, R. Kikinis

  Engineering in Medicine and Biology Magazine, IEEE. 10/2006;

  In this article, we report efforts to integrate a number of state-of-the-art technologies for MRI-guided neurosurgery at the Brigham and Women's Hospital (BWH) in Boston. These include advancedIn this article, we report efforts to integrate a number of state-of-the-art technologies for MRI-guided neurosurgery at the Brigham and Women's Hospital (BWH) in Boston. These include advanced intraoperative imaging, image registration, visualization, navigation, minimally invasive ablative therapies, and robotics. This is part of a multidisciplinary Image-Guided Therapy Program that comprises several key research thrusts, including the surgical planning laboratory, magnetic resonance therapy (MRT), focused ultrasound surgery, thermal ablation, and neurosurgery

• Needle artifact localization in 3T MR images.

  Authors: S P DiMaio, D F Kacher, R.E. Ellis, G. Fichtinger, N Hata, G P Zientara, L P Panych, R Kikinis, F A Jolesz

  Studies in health technology and informatics. 02/2006; 119:120-5.

  This work explores an image-based approach for localizing needles during MRI-guided interventions, for the purpose of tracking and navigation. Susceptibility artifacts for several needles of varyingThis work explores an image-based approach for localizing needles during MRI-guided interventions, for the purpose of tracking and navigation. Susceptibility artifacts for several needles of varying thickness were imaged, in phantoms, using a 3 tesla MRI system, under a variety of conditions. The relationship between the true needle positions and the locations of artifacts within the images, determined both by manual and automatic segmentation methods, have been quantified and are presented here.

• DTI and MTR abnormalities in schizophrenia: analysis of white matter integrity.

  Authors: M Kubicki, H Park, C.-F. Westin, P G Nestor, R V Mulkern, S E Maier, M Niznikiewicz, E E Connor, J J Levitt, M Frumin, R Kikinis, F A Jolesz, R W McCarley, M E Shenton

  NeuroImage. 08/2005; 26(4):1109-18.

  Diffusion tensor imaging (DTI) studies in schizophrenia demonstrate lower anisotropic diffusion within white matter due either to loss of coherence of white matter fiber tracts, to changes in theDiffusion tensor imaging (DTI) studies in schizophrenia demonstrate lower anisotropic diffusion within white matter due either to loss of coherence of white matter fiber tracts, to changes in the number and/or density of interconnecting fiber tracts, or to changes in myelination, although methodology as well as localization of such changes differ between studies. The aim of this study is to localize and to specify further DTI abnormalities in schizophrenia by combining DTI with magnetization transfer imaging (MTI), a technique sensitive to myelin and axonal alterations in order to increase specificity of DTI findings. 21 chronic schizophrenics and 26 controls were scanned using Line-Scan-Diffusion-Imaging and T1-weighted techniques with and without a saturation pulse (MT). Diffusion information was used to normalize co-registered maps of fractional anisotropy (FA) and magnetization transfer ratio (MTR) to a study-specific template, using the multi-channel daemon algorithm, designed specifically to deal with multidirectional tensor information. Diffusion anisotropy was decreased in schizophrenia in the following brain regions: the fornix, the corpus callosum, bilaterally in the cingulum bundle, bilaterally in the superior occipito-frontal fasciculus, bilaterally in the internal capsule, in the right inferior occipito-frontal fasciculus and the left arcuate fasciculus. MTR maps demonstrated changes in the corpus callosum, fornix, right internal capsule, and the superior occipito-frontal fasciculus bilaterally; however, no changes were noted in the anterior cingulum bundle, the left internal capsule, the arcuate fasciculus, or inferior occipito-frontal fasciculus. In addition, the right posterior cingulum bundle showed MTR but not FA changes in schizophrenia. These findings suggest that, while some of the diffusion abnormalities in schizophrenia are likely due to abnormal coherence, or organization of the fiber tracts, some of these abnormalities may, in fact, be attributed to or coincide with myelin/axonal disruption.

• MRI-based thermometry and thermal dosimetry during focused ultrasound thermal ablation of uterine leiomyomas

  Authors: N. McDannold, C. Tempany, E.A. Stewart, F.A. Jolesz, K. Hynynen

  Ultrasonics Symposium, 2004 IEEE; 09/2004

  MRI-based temperature imaging and thermal dosimetry were tested during focused ultrasound treatments of uterine leiomyomas (fibroids). Imaging data from the treatment of 62 fibroids in 50 women wereMRI-based temperature imaging and thermal dosimetry were tested during focused ultrasound treatments of uterine leiomyomas (fibroids). Imaging data from the treatment of 62 fibroids in 50 women were analyzed to test the ability of thermal dose maps acquired during treatment to predict the resulting non-perfused area in contrast-enhanced images acquired immediately after treatment. Also, the variation in the peak temperature rise achieved was compared between patients and between sonications within treatments. On average, the non-perfused area was 1.9±0.7 times as large as the area that achieved a thermal dose of 240 equivalent min at 43°C. The non-perfused area agreed better with a lower threshold; it was 1.2±0.4 times as large as the area that achieved a thermal dose of ≥18 equivalent min at 43°C. Agreement was better for smaller treatments. For large treatments at least, the non-perfused area was clearly enlarged by vascular occlusion to regions within the fibroid that were outside that directly targeted. Variations in the peak temperature rise were as large as a factor of two for similar acoustic parameters, both between patients and within individual treatments. These results demonstrate the need and usefulness of quantitative temperature mapping during focused ultrasound surgery.

• Large volume blood-brain barrier disruption by low frequency focused ultrasound: a method for targeted drug delivery and molecular imaging

  Authors: K. Hynynen, N. McDannold, N. Vykhodtseva, S. Raymond, F.A. Jolesz, N. Sheikov

  Ultrasonics Symposium, 2004 IEEE; 09/2004

  The paper explores the feasibility of using low frequency image guided focused ultrasound as a noninvasive method to temporarily disrupt the blood-brain barrier (BBB) at targeted locations. ThisThe paper explores the feasibility of using low frequency image guided focused ultrasound as a noninvasive method to temporarily disrupt the blood-brain barrier (BBB) at targeted locations. This method could provide a means for targeted delivery of therapeutic or diagnostic agents to the brain. Brains of rabbits were targeted with 20 s burst sonications (10 ms, repetition frequency, 1 Hz.) using a focused ultrasound transducer (frequency, 260 kHz; diameter, 10 cm; radius of curvature, 8 cm) in a clinical magnetic resonance imaging (MRI) scanner. The peak rarefactional pressure amplitude during the burst was varied between 0.2 and 0.9 MPa. Each sonication was performed 10 s after an intravenous injection of an ultrasound contrast agent (Optison^®). The disruption of the BBB was evaluated by injecting MRI contrast agent (Magnevist^®). The animals were sacrificed at different times between 4 h and 5 weeks, after which histology or electron microscopy evaluation was performed. The results demonstrated that low frequency ultrasound bursts could induce local, reversible disruption of the BBB without undesired long-term effects. Electron microscopy showed that a large particle (horseradish peroxidase; molecular weight 40 kDa) could be delivered through the BBB disruption. This frequency is desirable since it can be focused through the intact skull without significant distortion of the ultrasound beam.

• Non-invasive opening of BBB by focused ultrasound.

  Authors: K Hynynen, N McDannold, N. Vykhodtseva, F A Jolesz

  Acta neurochirurgica. Supplement. 02/2003; 86:555-8.

  Blood brain barrier (BBB) is a major barrier for delivering therapeutic agents in the brain. In this study we investigated the feasibility of open the BBB by using focused ultrasound. Rabbit brainsBlood brain barrier (BBB) is a major barrier for delivering therapeutic agents in the brain. In this study we investigated the feasibility of open the BBB by using focused ultrasound. Rabbit brains were exposed to pulsed focused ultrasound while injecting ultrasound contrast agent containg microbubbles intravenously. The BBB opening was measured after the sonications by injecting MRI contrast agent i.v. and evaluating the local enhancement in the brain. Low ultrasound powers and pressure amplitudes were found to cause focal enhancement. Before sacrificing the animals trypan blue was also injected i.v.. After the sacrifice of the animals blue spots were found in the brain in the sonicated locations. This method may have potential for targeted delivery of macromolecules in the brain.

• Surgical navigation in the open MRI.

  Authors: A Nabavi, D T Gering, D F Kacher, I F Talos, W M Wells, R Kikinis, P McL Black, F A Jolesz

  Acta neurochirurgica. Supplement. 02/2003; 85:121-5.

  The introduction of MRI into neurosurgery has opened multiple avenues, but also introduced new challenges. The open-configuration intraoperative MRI installed at the Brigham and Women's Hospital inThe introduction of MRI into neurosurgery has opened multiple avenues, but also introduced new challenges. The open-configuration intraoperative MRI installed at the Brigham and Women's Hospital in 1996 has been used for more than 500 open craniotomies and beyond 100 biopsies. Furthermore the versatile applicability, employing the same principles, is evident by its frequent use in other areas of the body. However, while intraoperative scanning in the SignaSP yielded unprecedented imaging during neurosurgical procedures their usage for navigation proved bulky and unhandy. To be fully integrated into the procedure, acquisition and display of intraoperative data have to be dynamic and primarily driven by the surgeon performing the procedure. To use the benefits of computer-assisted navigation systems together with immediate availability of intraoperative imaging we developed a software package. This "3D Slicer" has been used routinely for biopsies and open craniotomies. The system is stable and reliable. Pre- and intraoperative data can be visualized to plan and perform surgery, as well as to accommodate for intraoperative deformations, "brain shift", by providing online data acquisition.

• Future perspectives in intraoperative imaging.

  Authors: F A Jolesz

  Acta neurochirurgica. Supplement. 02/2003; 85:7-13.

  Of all the advances in imaging science in the past twenty years, none has had a greater impact than Magnetic Resonance Imaging. Since its introduction as a diagnostic tool in the mid-1980's, MRI hasOf all the advances in imaging science in the past twenty years, none has had a greater impact than Magnetic Resonance Imaging. Since its introduction as a diagnostic tool in the mid-1980's, MRI has evolved into the premier neuroimaging modality, and with the addition of higher field magnets, we are able to achieve spatial resolution of such superb quality that even the most exquisite details of the brain anatomy can be visualized. With the implementation of intraoperative, neurosurgical MRI, we can not only monitor brain shifts and deformations; we can achieve intraoperative navigation using intraoperative image updates. In the future, intraoperative MRI can be used not only to localize, target, and resect brain tumors and other lesions but also to fully comprehend the surrounding cortical and white matter functional anatomy. In addition to the inclusion of new imaging methods such as diffusion tensor imaging, new therapeutic methods will be applied. Especially encouraging are the promising results in MRI-guided Focused Ultrasound Surgery, in which the non-invasive thermal ablation of tumors is monitored and controlled by MRI. With the clinical introduction of these advances, intraoperative MRI is changing the face of Neurosurgery today.

• Voxel-based morphometric analysis of gray matter in first episode schizophrenia.

  Authors: M Kubicki, M E Shenton, D F Salisbury, Y Hirayasu, K Kasai, R Kikinis, F A Jolesz, R W McCarley

  NeuroImage. 12/2002; 17(4):1711-9.

  Voxel-based morphometry (VBM) may afford a more rapid and extensive survey of gray matter abnormalities in schizophrenia than manually drawn region of interest (ROI) analysis, the current goldVoxel-based morphometry (VBM) may afford a more rapid and extensive survey of gray matter abnormalities in schizophrenia than manually drawn region of interest (ROI) analysis, the current gold standard in structural MRI. Unfortunately, VBM has not been validated by comparison with ROI analyses, nor used in first-episode patients with schizophrenia or affective psychosis, who lack structural changes associated with chronicity. An SPM99-based implementation of VBM was used to compare a group of 16 patients with first-episode schizophrenia and a group of 18 normal controls and, as a further comparison, 16 first-episode patients with affective psychosis. All groups were matched for age and handedness. High spatial resolution structural images were normalized to the SPM99 template and then segmented, smoothed, and subjected to an ANCOVA. Schizophrenia vs control group comparisons: Voxel-by-voxel comparison of gray matter densities showed that only the left STG region was significantly different when corrected for multiple comparisons (P <.05), consistent with our previously reported manual ROI results. Analysis of the extent of voxel clusters, replicated with permutation analyses, revealed group differences in bilateral anterior cingulate gyri and insula (not previously examined by us with manually drawn ROI) and unilateral parietal lobe, but not in medial temporal lobe (where our ROI analysis had shown differences). However, use of a smaller smoothing kernel and a small volume correction revealed left-sided hippocampal group differences. Affective psychosis comparisons: When the same statistical thresholding criteria were used, no significant differences between affective psychosis patients and controls were noted. Since a major interest was whether patients with affective psychosis shared some anatomical abnormalities with schizophrenia, we applied a small volume correction and searched within the regions that were significantly less dense in schizophrenia compared to control subjects. With this statistical correction, the insula showed, bilaterally, the same pattern of differences in affective disorder subjects as that in schizophrenic subjects, whereas both left STG and left hippocampus showed statistical differences between affectives and schizophrenics, indicating the abnormalities specific to first-episode schizophrenia. These findings suggest both the promise and utility of VBM in evaluating gray matter abnormalities. They further suggest the importance of comparing VBM findings with more traditional ROI analyses until the reasons for the differences between methods are determined.

• Processing and visualization for diffusion tensor MRI.

  Authors: C.-F. Westin, S E Maier, H Mamata, A Nabavi, F A Jolesz, R Kikinis

  Medical image analysis. 07/2002; 6(2):93-108.

  This paper presents processing and visualization techniques for Diffusion Tensor Magnetic Resonance Imaging (DT-MRI). In DT-MRI, each voxel is assigned a tensor that describes local water diffusion.This paper presents processing and visualization techniques for Diffusion Tensor Magnetic Resonance Imaging (DT-MRI). In DT-MRI, each voxel is assigned a tensor that describes local water diffusion. The geometric nature of diffusion tensors enables us to quantitatively characterize the local structure in tissues such as bone, muscle, and white matter of the brain. This makes DT-MRI an interesting modality for image analysis. In this paper we present a novel analytical solution to the Stejskal-Tanner diffusion equation system whereby a dual tensor basis, derived from the diffusion sensitizing gradient configuration, eliminates the need to solve this equation for each voxel. We further describe decomposition of the diffusion tensor based on its symmetrical properties, which in turn describe the geometry of the diffusion ellipsoid. A simple anisotropy measure follows naturally from this analysis. We describe how the geometry or shape of the tensor can be visualized using a coloring scheme based on the derived shape measures. In addition, we demonstrate that human brain tensor data when filtered can effectively describe macrostructural diffusion, which is important in the assessment of fiber-tract organization. We also describe how white matter pathways can be monitored with the methods introduced in this paper. DT-MRI tractography is useful for demonstrating neural connectivity (in vivo) in healthy and diseased brain tissue.

• Airway imaging in humans using hyperpolarized helium-3 MRI

  Authors: E.L. McKinstry, A.C. Tooker, K.S. Hong, P. Costello, F A Jolesz, M S Albert

  [Engineering in Medicine and Biology, 2002. 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] EMBS/BMES Conference, 2002. Proceedings of the Second Joint; 02/2002

  Most hyperpolarized gas MRI, involving dynamic imaging of the human lungs, requires specialized ultra-fast MRI pulse sequences or the necessity for multiple breaths of hyperpolarized helium. Thus,Most hyperpolarized gas MRI, involving dynamic imaging of the human lungs, requires specialized ultra-fast MRI pulse sequences or the necessity for multiple breaths of hyperpolarized helium. Thus, most current dynamic imaging techniques are not ideal for a clinical setting. By using a standard fast GRE pulse sequence on a GE Signa 1.5 T clinical MRI scanner outfitted with heterodyne functionality, we have developed a clinically feasible method for dynamic human lung imaging of the airways. The technique presented here exploits the non-renewability of hyperpolarized gas to achieve the first distal human airway images with up to 7^th generation resolution of airways. Additionally, this approach requires only a single inspiration of hyperpolarized helium. The airway images achieved may provide unique information about possible causes of pulmonary airway constriction diseases.

• Registration of 3-D intraoperative MR images of the brain using a finite-element biomechanical model.

  Authors: M. Ferrant, A Nabavi, B. Macq, F A Jolesz, R Kikinis, S K Warfield

  IEEE transactions on medical imaging. 01/2002; 20(12):1384-97.

  We present a new algorithm for the nonrigid registration of three-dimensional magnetic resonance (MR) intraoperative image sequences showing brain shift. The algorithm tracks key surfaces of objectsWe present a new algorithm for the nonrigid registration of three-dimensional magnetic resonance (MR) intraoperative image sequences showing brain shift. The algorithm tracks key surfaces of objects (cortical surface and the lateral ventricles) in the image sequence using a deformable surface matching algorithm. The volumetric deformation field of the objects is then inferred from the displacements at the boundary surfaces using a linear elastic biomechanical finite-element model. Two experiments on synthetic image sequences are presented, as well as an initial experiment on intraoperative MR images showing brain shift. The results of the registration algorithm show a good correlation of the internal brain structures after deformation, and a good capability of measuring surface as well as subsurface shift. We measured distances between landmarks in the deformed initial image and the corresponding landmarks in the target scan. Cortical surface shifts of up to 10 mm and subsurface shifts of up to 6 mm were recovered with an accuracy of 1 mm or less and 3 mm or less respectively.

• Evaluation of three-dimensional finite element-based deformable registration of pre- and intraoperative prostate imaging.

  Authors: A Bharatha, M Hirose, N Hata, S K Warfield, M. Ferrant, K H Zou, E Suarez-Santana, J. Ruiz-Alzola, A D'Amico, R A Cormack, R Kikinis, F A Jolesz, C M Tempany

  Medical physics. 01/2002; 28(12):2551-60.

  In this report we evaluate an image registration technique that can improve the information content of intraoperative image data by deformable matching of preoperative images. In this study,In this report we evaluate an image registration technique that can improve the information content of intraoperative image data by deformable matching of preoperative images. In this study, pretreatment 1.5 tesla (T) magnetic resonance (MR) images of the prostate are registered with 0.5 T intraoperative images. The method involves rigid and nonrigid registration using biomechanical finite element modeling. Preoperative 1.5 T MR imaging is conducted with the patient supine, using an endorectal coil, while intraoperatively, the patient is in the lithotomy position with a rectal obturator in place. We have previously observed that these changes in patient position and rectal filling produce a shape change in the prostate. The registration of 1.5 T preoperative images depicting the prostate substructure [namely central gland (CG) and peripheral zone (PZ)] to 0.5 T intraoperative MR images using this method can facilitate the segmentation of the substructure of the gland for radiation treatment planning. After creating and validating a dataset of manually segmented glands from images obtained in ten sequential MR-guided brachytherapy cases, we conducted a set of experiments to assess our hypothesis that the proposed registration system can significantly improve the quality of matching of the total gland (TG), CG, and PZ. The results showed that the method statistically-significantly improves the quality of match (compared to rigid registration), raising the Dice similarity coefficient (DSC) from prematched coefficients of 0.81, 0.78, and 0.59 for TG, CG, and PZ, respectively, to 0.94, 0.86, and 0.76. A point-based measure of registration agreement was also improved by the deformable registration. CG and PZ volumes are not changed by the registration, indicating that the method maintains the biomechanical topology of the prostate. Although this strategy was tested for MRI-guided brachytherapy, the preliminary results from these experiments suggest that it may be applied to other settings such as transrectal ultrasound-guided therapy, where the integration of preoperative MRI may have a significant impact upon treatment planning and guidance.

• Neurosurgical suite of the future. II.

  Authors: F A Jolesz

  Neuroimaging clinics of North America. 12/2001; 11(4):581-92.

  The role of imaging in diagnosis and therapy has been accepted by physicians. This favorable reception of minimally invasive procedures resulted in the recognition of the feasibility of image-guidedThe role of imaging in diagnosis and therapy has been accepted by physicians. This favorable reception of minimally invasive procedures resulted in the recognition of the feasibility of image-guided approaches. Although radiology has combined imaging with various novel therapeutic methods, the full use of advanced imaging technology has not yet been accomplished. The current trend is the evolution of integrated therapy delivery systems in which advanced imaging modalities are closely linked with high performance computing. Obviously, the operating room of the future will accommodate various instruments, tools and devices, which are attached to the imaging systems and controlled by image-based feedback.

• Neuronavigation in interventional MR imaging. Frameless stereotaxy.

  Authors: F A Jolesz, R Kikinis, I F Talos

  Neuroimaging clinics of North America. 12/2001; 11(4):685-93, ix.

  The main thrust of diagnostic MR imaging is to discern normal and pathologic patient morphology and function. Intraprocedural imaging, however, serves a different goal: to furnish the surgeon orThe main thrust of diagnostic MR imaging is to discern normal and pathologic patient morphology and function. Intraprocedural imaging, however, serves a different goal: to furnish the surgeon or interventionalist with updates on intraoperative changes and how they may modify preintervention data. Although researchers have not established whether MR image-guided therapy can improve clinical outcomes and reduce complication rates definitively, the intraoperative and preoperative data generated will improve the ability of every neurosurgeon to navigate in the surgical field more accurately.

• Intraoperative MR systems. Midfield approaches.

  Authors: R B Schwartz, D F Kacher, R S Pergolizzi, F A Jolesz

  Neuroimaging clinics of North America. 12/2001; 11(4):629-44.

  Intraoperative MR imaging provides an unrestricted view of intracranial structures and lesions that has revolutionized the way that neurosurgery is performed in the authors' institution.Intraoperative MR imaging provides an unrestricted view of intracranial structures and lesions that has revolutionized the way that neurosurgery is performed in the authors' institution. Intraoperative imaging allows the practitioner to update and adjust the approach to intracranial lesions continuously. With this system, important anatomic and vascular structures can be successfully avoided; boundaries of low-grade tumors can be accurately defined, and foci of possible higher grade within these lesions can be identified; foci of high-grade astrocytomas can be differentiated from radiated brain; hyperacute hemorrhage or infarction during and after procedures can be determined; and the possible communication of cystic collections with CSF can be ascertained. These advantages provide a level of comfort to the surgeon and a presumptive margin of safety to the patient that is unattainable during conventional surgical approaches, and given the choice, the authors' neurosurgeons would prefer to operate in the interventional magnet. Preliminary reports concerning the efficacy and usefulness of MR-guided navigational tools for the performance of neurosurgery are encouraging, as noted earlier, Wirtz et al have shown that the more extensive removal of glioblastomas afforded by intraoperative MR leads to significantly prolonged patient survival compared with conventional surgery. Further outcomes analysis must be performed, however, to determine whether these new techniques significantly decrease overall long-term morbidity or increase survival in those patients who have low-grade astrocytomas.

• Prefrontal cortex, negative symptoms, and schizophrenia: an MRI study.

  Authors: C G Wible, J Anderson, M E Shenton, A Kricun, Y Hirayasu, S Tanaka, J J Levitt, B F O'Donnell, R Kikinis, F A Jolesz, R W McCarley

  Psychiatry research. 12/2001; 108(2):65-78.

  The present study measured prefrontal cortical gray and white matter volume in chronic, male schizophrenic subjects who were characterized by a higher proportion of mixed or negative symptoms thanThe present study measured prefrontal cortical gray and white matter volume in chronic, male schizophrenic subjects who were characterized by a higher proportion of mixed or negative symptoms than previous patients that we have evaluated. Seventeen chronic male schizophrenic subjects and 17 male control subjects were matched on age and handedness. Regions of interest (ROI) were measured using high-resolution magnetic resonance (MR) acquisitions consisting of contiguous 1.5-mm slices of the entire brain. No significant differences were found between schizophrenic and control subjects in mean values for prefrontal gray matter volume in either hemisphere. However, right prefrontal white matter was significantly reduced in the schizophrenic group. In addition, right prefrontal gray matter volume was significantly correlated with right hippocampal volume in the schizophrenic, but not in the control group. Furthermore, an analysis in which the current data were combined with those from a previous study showed that schizophrenic subjects with high negative symptom scores had significantly smaller bilateral white matter volumes than those with low negative symptom scores. White matter was significantly reduced in the right hemisphere in this group of schizophrenic subjects. Prefrontal volumes were also associated with negative symptom severity and with volumes of medial-temporal lobe regions - two results that were also found previously in schizophrenic subjects with mostly positive symptoms. These results underscore the importance of temporal-prefrontal pathways in the symptomatology of schizophrenia, and they suggest an association between prefrontal abnormalities and negative symptoms.

• Noninvasive MR imaging-guided focal opening of the blood-brain barrier in rabbits.

  Authors: K Hynynen, N McDannold, N. Vykhodtseva, F A Jolesz

  Radiology. 10/2001; 220(3):640-6.

  PURPOSE: To determine if focused ultrasound beams can be used to locally open the blood-brain barrier without damage to surrounding brain tissue and if magnetic resonance (MR) imaging can be used toPURPOSE: To determine if focused ultrasound beams can be used to locally open the blood-brain barrier without damage to surrounding brain tissue and if magnetic resonance (MR) imaging can be used to monitor this procedure. MATERIALS AND METHODS: The brains of 18 rabbits were sonicated (pulsed sonication) in four to six locations, with temporal peak acoustic power ranging from 0.2 to 11.5 W. Prior to each sonication, a bolus of ultrasonographic (US) contrast agent was injected into the ear vein of the rabbit. A series of fast or spoiled gradient-echo MR images were obtained during the sonications to monitor the temperature elevation and potential tissue changes. Contrast material-enhanced MR images obtained minutes after sonications and repeated 1-48 hours later were used to depict blood-brain barrier opening. Whole brain histologic evaluation was performed. RESULTS: Opening of the blood-brain barrier was confirmed with detection of MR imaging contrast agent at the targeted locations. The lowest power levels used produced blood-brain barrier opening without damage to the surrounding neurons. Contrast enhancement correlated with the focal signal intensity changes in the magnitude fast spoiled gradient-echo MR images. CONCLUSION: The blood-brain barrier can be consistently opened with focused ultrasound exposures in the presence of a US contrast agent. MR imaging signal intensity changes may be useful in the detection of blood-brain barrier opening during sonication.

• MR imaging-guided prostate biopsy with surgical navigation software: device validation and feasibility.

  Authors: N Hata, M Jinzaki, D Kacher, R Cormak, D Gering, A Nabavi, S G Silverman, A V D'Amico, R Kikinis, F A Jolesz, C M Tempany

  Radiology. 08/2001; 220(1):263-8.

  Magnetic resonance (MR) imaging--guided prostate biopsy in a 0.5-T open imager is described, validated in phantom studies, and performed in two patients. The needles are guided by using fastMagnetic resonance (MR) imaging--guided prostate biopsy in a 0.5-T open imager is described, validated in phantom studies, and performed in two patients. The needles are guided by using fast gradient-recalled echo and T2-weighted fast spin-echo images. Surgical navigation software provided T2-weighted images critical to targeting the peripheral zone and the tumor. MR imaging can be used to guide prostate biopsy.

• Line scan diffusion tensor MRI of the cervical spinal cord in preterm infants.

  Authors: B P Murphy, G P Zientara, P S Huppi, S E Maier, P D Barnes, F A Jolesz, J J Volpe

  Journal of magnetic resonance imaging : JMRI. 07/2001; 13(6):949-53.

  Line scan diffusion tensor magenetic resonance imaging (DT-MRI) of the cervical spinal cord was demonstrated in vivo for unsedated preterm (gestational age 24-30 weeks at birth), very low birthweightLine scan diffusion tensor magenetic resonance imaging (DT-MRI) of the cervical spinal cord was demonstrated in vivo for unsedated preterm (gestational age 24-30 weeks at birth), very low birthweight (birthweight 620-1300 g) infants at postmenstrual ages from 29-40 weeks. Scalar invariant measures of diffusion [apparent diffusion coefficient (ADC) and relative anisotropy (RA)] determined from a cervical cord region of interest in each case are reported, characterizing the maturational status of the normal third trimester and newborn spinal cord. Mean ADC of 11 infants was 1.2 +/- 0.1 microm(2)/msec and the mean RA was 24.3 +/- 4.9%. Normal infant cord neural fiber tract morphology was visualized using a mapping of the predominant diffusion tensor eigenvector. Potential clinical applications of line scan DT-MRI of the spinal cord of preterm and term newborns for assessment of spinal cord injury are discussed. J. Magn. Reson. Imaging 2001;13:949-953.