Effects of Cognitive Behavioral Therapy on Neural Processing of Agoraphobia-Specific Stimuli in Panic Disorder and Agoraphobia.

BACKGROUND: Patients suffering from panic disorder and agoraphobia are significantly impaired in daily life due to anxiety about getting into a situation due to apprehension about experiencing a panic attack, especially if escape may be difficult. Dysfunctional beliefs and behavior can be changed with cognitive behavioral therapy; however, the neurobiological effects of such an intervention on the anticipation and observation of agoraphobia-specific stimuli are unknown. METHODS: We compared changes in neural activation by measuring the blood oxygen level-dependent signal of 51 patients and 51 healthy controls between scans before and those after treatment (group by time interaction) during anticipation and observation of agoraphobia-specific compared to neutral pictures using 3-T fMRI. RESULTS: A significant group by time interaction was observed in the ventral striatum during anticipation and in the right amygdala during observation of agoraphobia-specific pictures; the patients displayed a decrease in ventral striatal activation during anticipation from pre- to posttreatment scans, which correlated with clinical improvement measured with the Mobility Inventory. During observation, the patients displayed decreased activation in the amygdala. These activational changes were not observed in the matched healthy controls. CONCLUSIONS: For the first time, neural effects of cognitive behavioral therapy were shown in patients suffering from panic disorder and agoraphobia using disorder-specific stimuli. The decrease in activation in the ventral striatum indicates that cognitive behavioral therapy modifies anticipatory anxiety and may ameliorate abnormally heightened salience attribution to expected threatening stimuli. The decreased amygdala activation in response to agoraphobia-specific stimuli indicates that cognitive behavioral therapy can alter the basal processing of agoraphobia-specific stimuli in a core region of the fear network.

DTI fiber tractography of cerebro-cerebellar pathways and clinical evaluation of ataxia in childhood posterior fossa tumor survivors.

Pediatric posterior fossa (PF) tumor survivors experience long-term motor deficits. Specific cerebrocerebellar connections may be involved in incidence and severity of motor dysfunction. We examined the relationship between long-term ataxia as well as fine motor function and alteration of differential cerebellar efferent and afferent pathways using diffusion tensor imaging (DTI) and tractography. DTI-based tractography was performed in 19 patients (10 pilocytic astrocytoma (PA) and 9 medulloblastoma patients (MB)) and 20 healthy peers. Efferent Cerebello-Thalamo-Cerebral (CTC) and afferent Cerebro-Ponto-Cerebellar (CPC) tracts were reconstructed and analyzed concerning fractional anisotropy (FA) and volumetric measurements. Clinical outcome was assessed with the International Cooperative Ataxia Rating Scale (ICARS). Kinematic parameters of fine motor function (speed, automation, variability, and pressure) were obtained by employing a digitizing graphic tablet. ICARS scores were significantly higher in MB patients than in PA patients. Poorer ICARS scores and impaired fine motor function correlated significantly with volume loss of CTC pathway in MB patients, but not in PA patients. Patients with pediatric post-operative cerebellar mutism syndrome showed higher loss of CTC pathway volume and were more atactic. CPC pathway volume was significantly reduced in PA patients, but not in MB patients. Neither relationship was observed between the CPC pathway and ICARS or fine motor function. There was no group difference of FA values between the patients and healthy peers. Reduced CTC pathway volumes in our cohorts were associated with severity of long-term ataxia and impaired fine motor function in survivors of MBs. We suggest that the CTC pathway seems to play a role in extent of ataxia and fine motor dysfunction after childhood cerebellar tumor treatment. DTI may be a useful tool to identify relevant structures of the CTC pathway and possibly avoid surgically induced long-term neurological sequelae.

Cerebral white matter fractional anisotropy and tract volume as measured by MR imaging are associated with impaired cognitive and motor function in pediatric posterior fossa tumor survivors.

BACKGROUND: Disease and therapy cause brain damage and subsequent functional loss in pediatric patients with posterior fossa tumors. Treatment-related toxicity factors are resection in patients with pilocytic astrocytoma (PA) and, additionally, cranio-spinal irradiation together with chemotherapy in patients with medulloblastoma (MB). We tested whether damage to white matter (WM) as revealed by diffusion tensor MR imaging (DTI) correlated with specific cognitive and motor impairments in survivors of pediatric posterior fossa tumors. PROCEDURES: Eighteen MB (mean age ± SD, 15.2 ± 4.9 y) and 14 PA (12.6 ± 5.0 y) survivors were investigated with DTI on a 3-Tesla-MR system. We identified fractional anisotropy (FA) of WM, the volume ratio of WM to gray matter and cerebrospinal fluid (WM/GM + CSF), and volume of specific frontocerebellar tracts. Ataxia was assessed using the International Cooperative Ataxia Rating Scale (ICARS), while the Wechsler Intelligence Scale for Children determined full-scale intelligence quotients (FSIQ). Amsterdam Neuropsychological Tasks (ANT) was used to assess processing speed. Handwriting automation was analyzed using a digitizing graphic tablet. RESULTS: The WM/GM + CSF ratio correlated significantly with cognitive measures (IQ, P = 0.002; ANT baseline speed, P = 0.04; ANT shifting attention, P = 0.004). FA of skeletonized tracts correlated significantly with FSIQ (P = 0.008), ANT baseline speed (P = 0.028) and ANT shifting attention (P = 0.045). Moreover, frontocerebellar tract volumes correlated with both the FSIQ (P = 0.011) and ICARS (P = 0.007). CONCLUSION: DTI provides a method for quantification of WM damage by tumor and by therapy-associated effects in survivors of pediatric posterior fossa tumors. DTI-derived WM integrity may be a representative marker for cognitive and motor deterioration.

Fronto-cerebellar fiber tractography in pediatric patients following posterior fossa tumor surgery.

OBJECTIVE: Fronto-cerebellar association fibers (FCF) are involved in neurocognitive regulatory circuitry. This may also be relevant for cerebellar mutism syndrome (CMS) as a complication following posterior fossa tumor removal in children. In the present study, we investigated FCF by diffusion tensor imaging in affected children and controls. METHODS: Diffusion-weighted MR imaging at 3 T (GE) allowed tractography of FCF using a fiber tracking algorithm software (Brainlab 2.6) in 29 patients after posterior fossa tumor removal and in 10 healthy peers. Fiber tract volumes were assessed and fiber signals were evaluated in a semiquantitative manner along the anatomical course. RESULTS: Volumes of FCF revealed significant diminished values in pediatric patients with symptoms of CMS (19.3 ± 11.7 cm(3)) when compared with patients without symptoms of CMS (26.9 ± 11.9 cm(3)) and with healthy peers (36.5 ± 13.82 cm(3)). In medulloblastoma patients, the volume of FCF was also significantly reduced in patients with symptoms of CMS despite having the same antitumor therapy. In semiquantitative analysis of the fiber tract signals, differences were observed in the superior cerebellar peduncles and midline cerebellar structures in patients with symptoms of CMS. CONCLUSION: Using DTI, which allows the visualization of fronto-cerebellar fiber tracts, lower FCF tract volumes and diminished fiber signal intensities at the level of the superior cerebellar peduncles and in midline cerebellar structures were identified in patients with postoperative symptoms of CMS. Our study refers to the role of a neural circuitry between frontal lobes and the cerebellum being involved in neurocognitive impairment after posterior fossa tumor treatment in children.

Supratentorial neurometabolic alterations in pediatric survivors of posterior fossa tumors.

PURPOSE: Therapy and tumor-related effects such as hypoperfusion, internal hydrocephalus, chemotherapy, and irradiation lead to significant motor and cognitive sequelae in pediatric posterior fossa tumor survivors. A distinct proportion of those factors related to the resulting late effects is hitherto poorly understood. This study aimed at separating the effects of neurotoxic factors on central nervous system metabolism by using H-1 MR spectroscopy to quantify cerebral metabolite concentrations in these patients in comparison to those in age-matched healthy peers. METHODS AND MATERIALS: Fifteen patients with World Health Organization (WHO) I pilocytic astrocytoma (PA) treated by resection only, 24 patients with WHO IV medulloblastoma (MB), who additionally received chemotherapy and craniospinal irradiation, and 43 healthy peers were investigated using single-volume H-1 MR spectroscopy of parietal white matter and gray matter. RESULTS: Concentrations of N-acetylaspartate (NAA) were significantly decreased in white matter (p < 0.0001) and gray matter (p < 0.0001) of MB patients and in gray matter (p = 0.005) of PA patients, compared to healthy peers. Decreased creatine concentrations in parietal gray matter correlated significantly with older age at diagnosis in both patient groups (MB patients, p = 0.009, r = 0.52; PA patients, p = 0.006, r = 0.7). Longer time periods since diagnosis were associated with lower NAA levels in white matter of PA patients (p = 0.008, r = 0.66). CONCLUSIONS: Differently decreased NAA concentrations were observed in both PA and MB groups of posterior fossa tumor patients. We conclude that this reflects a disturbance of the neurometabolic steady state of normal-appearing brain tissue due to the tumor itself and to the impact of surgery in both patient groups. Further incremental decreases of metabolite concentrations in MB patients may point to additional harm caused by irradiation and chemotherapy. The stronger decrease of NAA in MB patients may correspond to the additional damage of combined irradiation and chemotherapy on neuroaxonal cell viability and number.

Perfusion imaging of cerebral arteriovenous malformations: a study comparing quantitative continuous arterial spin labeling and dynamic contrast-enhanced magnetic resonance imaging at 3 T.

Assessment of hemodynamics in arteriovenous malformations (AVMs) is important for estimating the risk of bleeding as well as planning and monitoring therapy. In tissues with perfusion values significantly higher than cerebral cortex, continuous arterial spin labeling (CASL) permits both adequate representation and quantification of perfusion. Thirteen patients who had cerebral AVMs were examined with two magnetic resonance imaging (MRI) techniques: perfusion imaging using a CASL technique with two delay times, 800 and 1200 ms, and T(2)-weighted dynamic contrast-enhanced MRI (T(2)-DCE-MRI). The signal-to-noise ratio obtained in our study with the CASL technique at 3 T was sufficient to estimate perfusion in gray matter. Both nidal and venous perfusion turned out larger by factors of 1.71±2.01 and 2.48±1.51 in comparison to T(2)-DCE-MRI when using CASL at delay times of 800 and 1200 ms, respectively. Moreover, the venous and nidal perfusion values of the AVMs measured at T(2)-DCE-MRI did not correlate with those observed at CASL. Evaluation of average perfusion values yielded significantly different results when using a shorter versus a longer delay time. Average gray matter perfusion was 15.8% larger when measured at delay times of w=800 ms versus w=1200 ms, while nidal perfusion was 15.7% larger and venous perfusion was 34.6% larger, respectively. In conclusion, the extremely high perfusion within an AVM could be successfully quantified using CASL. A shorter postlabeling delay time of w=800 ms seems to be more appropriate than a longer time of w=1200 ms because of possible inflow of unlabeled spins at the latter.

Effects of short-term stress-like cortisol on cerebral metabolism: a proton magnetic resonance spectroscopy study at 3.0 T.

Preclinical and clinical studies suggest that glucocorticoids disturb cognitive performance and neuronal integrity. MR spectroscopy studies have tried to track these effects and correlate long-term effects of glucocorticoids with concentration changes of cerebral metabolites. However, a systematic spectroscopic study on short-term exposure to corticosteroids, in a dosage sufficient to impair memory performance, is lacking. Thus, it is not known when glucocorticoid effects become visible at 1H-MRS in vivo. Therefore, employing localized 1H-MRS at 3T we quantitatively investigated the effects of a 4-day cortisol exposure (160 mg/d) on brain metabolites in vivo in a double blind and placebo-controlled cross-over study of 21 healthy subjects. Spectroscopic measurements were performed in four different brain regions, including the posterior cingulate gyrus, right frontal white matter, left and right anterior hippocampus using the PRESS method. Our results show, after 4 days of cortisol intake and despite a nearly 3-fold increase in serum cortisol concentration, for none of the investigated metabolites a significant corticosteroid-induced concentration change. Our results show that contrary to reported long-term effects, short-term hydrocortisone exposure at a stress-like dosage does not lead to changes of prominent cerebral metabolites, including N-acetylaspartate, creatine and phosphocreatine, choline-containing metabolites, myo-inositol and glutamate.

Differences in supratentorial damage of white matter in pediatric survivors of posterior fossa tumors with and without adjuvant treatment as detected by magnetic resonance diffusion tensor imaging.

PURPOSE: To elucidate morphologic correlates of brain dysfunction in pediatric survivors of posterior fossa tumors by using magnetic resonance diffusion tensor imaging (DTI) to examine neuroaxonal integrity in white matter. PATIENTS AND METHODS: Seventeen medulloblastoma (MB) patients who had received surgery and adjuvant treatment, 13 pilocytic astrocytoma (PA) patients who had been treated only with surgery, and age-matched healthy control subjects underwent magnetic resonance imaging on a 3-Tesla system. High-resolution conventional T1- and T2-weighted magnetic resonance imaging and DTI data sets were obtained. Fractional anisotropy (FA) maps were analyzed using tract-based spatial statistics, a part of the Functional MRI of the Brain Software Library. RESULTS: Compared with control subjects, FA values of MB patients were significantly decreased in the cerebellar midline structures, in the frontal lobes, and in the callosal body. Fractional anisotropy values of the PA patients were not only decreased in cerebellar hemispheric structures as expected, but also in supratentorial parts of the brain, with a distribution similar to that in MB patients. However, the amount of significantly decreased FA was greater in MB than in PA patients, underscoring the aggravating neurotoxic effect of the adjuvant treatment. CONCLUSIONS: Neurotoxic mechanisms that are present in PA patients (e.g., internal hydrocephalus and damaged cerebellar structures affecting neuronal circuits) contribute significantly to the alteration of supratentorial white matter in pediatric posterior fossa tumor patients.

High-resolution depiction of the cranial nerves in the posterior fossa (N III-N XII) with 2D fast spin echo and 3D gradient echo sequences at 3.0 T.

PURPOSE: The objective of this study was to evaluate the influence of high-resolution imaging obtainable with the higher field strength of 3.0 T on the visualization of the brain nerves in the posterior fossa by using T(2)-weighted fast spin echo (FSE) and fast imaging employing steady-state gradient echo (GRE) sequences as the most suitable techniques to visualize each of the cranial nerves. MATERIALS AND METHODS: In total, 20 nerves were investigated on MR images of 12 volunteers each and selected for comparison, respectively, with the FSE sequences with 5-mm and 2-mm section thicknesses and GRE sequences acquired with a 3.0-T scanner and a quadrature head coil. The resulting MR images were evaluated by three independent readers who rated image quality according to depiction of anatomic detail and contrast with use of a rating scale. RESULTS: In general, decrease of the slice thickness showed a significant increase in the detection of nerves as well as in the image quality characteristics. As expected, artifacts were prominent in high-field imaging of the posterior fossa with GRE sequences. Nevertheless, comparing FSE and GRE imaging, the course of brain nerves and brainstem vessels was visualized best with use of the three-dimensional (3D) pulse sequence, although with respect to structural identification and contrast according to the rating scale, observer scores were not significantly improved. CONCLUSION: The comparison revealed the clear advantage of a thin section. The increased resolution enabled immediate identification of all brainstem nerves. Although image quality is impaired at GRE at high field strength, this sequence most distinctly and confidently depicted pertinent structures and enables 3D reconstruction in order to illustrate complex relations of the brainstem.

Decreased bilateral cortical representation patterns in writer's cramp: a functional magnetic resonance imaging study at 3.0 T.

Functional magnetic resonance imaging was used to characterize patterns of cortical activation in response to sensory and motor tasks in patients with writer's cramp. 17 patients and 17 healthy subjects were examined during finger-tapping, index finger flexion, and electrical median nerve stimulation of both hands during electromyographic monitoring. SPM2 was used to evaluate Brodmann area (BA) 4, 1, 2, 3, 6, 40. Patients showed decreased activation in the left BA 4 with motor tasks of both hands and the left BA 1-3 with right finger-tapping. With left finger-tapping there was bilateral underactivation of single areas of the somatosensory cortex. Patients exhibited decreased activation in the bilateral BA 6 with left motor tasks and in the right BA 6 with right finger-tapping. Patients had decreased activation in bilateral BA 40 with finger-tapping of both hands. The findings suggest decreased baseline activity or an impaired activation in response to motor tasks in BA 1-4, 6, 40 in patients with writer's cramp for the dystonic and the clinically unaffected hand.

Assessment of in vivo 1H magnetic resonance spectroscopy in the liver: a review.

With increased availability of magnetic resonance (MR) systems at ultra-high field strength for clinical studies, other organs besides the brain have received renewed consideration for MR spectroscopy (MRS). Because signal-to-noise ratio and chemical shift increase proportional to the static magnetic field, a concomitant increase in signal intensity and spectral resolution of metabolite resonances can be exploited. Improved resolution of adjacent metabolite peaks would not only provide for more accuracy of metabolite identification but also metabolite quantification. While the superiority of high-field imaging and spectroscopy has already been demonstrated clearly in the brain, this article reviewed issues around 1H MRS of the liver. These include optimization strategies such as coil technology, minimizing of motion artefacts using breath-holding and postprocessing of the spectra. Moreover, we reviewed the pertinent experience hitherto reported in the literature on potential clinical issues where liver MRS may be useful. These included determination and characterization of liver fat content, liver tumours and focal lesions. While these applications have been used experimentally, liver MRS does not yet have a clearly defined role in the clinical management of any disease state. Accordingly, it remains primarily a research modality to date.

High-resolution MRI of the wrist and finger joints in patients with rheumatoid arthritis: comparison of 1.5 Tesla and 3.0 Tesla.

The goal of this study was to compare magnetic resonance (MR) image quality at different field strengths for evaluating lesions in wrist and finger joints of patients with rheumatoid arthritis (RA) in order to determine whether the higher field strength provides diagnostic gain. The hand mainly affected in 17 RA patients was examined at 1.5 Tesla (T) and 3.0 T with comparable MR imaging (MRI) protocols. MR images were reviewed twice by two experienced radiologists using the Rheumatoid Arthritis MRI Scoring System (RAMRIS) of the OMERACT (Outcome Measures in Rheumatoid Arthritis Clinical Trials) group. Image quality was rated on a five-point scale using Friedmann's test and Kendall's W-test for statistical analysis. Image comparison revealed better image quality at higher field strength. Image quality of T1-weighted images was rated 14-22% better at 3.0 T compared with 1.5 T by both readers. Moreover, the rating for the T2-weighted-images acquired at 3.0 T was one point better in the five-point scale used. Inter-reader correlation for image quality, bone erosions/defects, edema and synovitis ranged between 0.6 and 0.9 at 3.0 T and between 0.6 and 0.8 at 1.5 T. Intra-reader correlation for these parameters was high at 0.8-1.0. MRI image quality of RA hands is superior at 3.0 T, while an acceptable image quality is achieved at 1.5 T, which improves the evaluation of extent of bone edema, synovitis and identification of small bone erosions.

MR colonoscopy at 3.0 T: comparison with 1.5 T in vivo and a colon model.

PURPOSE: Retrospectively, magnetic resonance (MR) colonography images obtained from a colon model and in routine examinations of patients screened for polyps were compared in terms of whether, and to what degree, image quality improved at a higher field strength of 3.0 T compared to 1.5 T. MATERIALS AND METHODS: One hundred twenty-eight MR colonography images from 40 patients, of whom 20 had each been scanned at 1.5 and 3.0 T, respectively, using a four-element phased-array torso coil, were compared. At both field strengths, imaging included T1-weighted fat-suppressed spoiled gradient-echo (T1-fs-GE), T2/T1-weighted fast imaging employing steady-state acquisition (FIESTA), and T2-weighted single-shot fast spin-echo (T2-SSFSE), with breath-hold technique. Using receiver operating characteristic analysis performed by seven readers, the three types of images from the colon model and from 20 patients each at 1.5 and 3.0 T were compared. While a time window of 20 s was allowed for picture assessment in a chance-generated succession of images on a monitor, image quality was rated with a score of 1-5 (1=very good; 5=very bad). Statistical significance was calculated with Mann-Whitney U test. RESULTS: At both field strengths, T2-SSFSE images received the best ratings, followed by FIESTA images (P=.001). Although, overall, the 3.0-T images obtained scores worse than those of the 1.5-T images, a better detection of phantom polyps was noted in the colon model (P=.001). CONCLUSION: Although MR colonography with the breath-hold technique using the same four-element phased-array coil at 3.0 and 1.5 T does not perform better at a higher field strength in general, an improved detection of small polyps may be obtained.

Local arterial infusion of superparamagnetic iron oxide particles in hepatocellular carcinoma: A feasibility and 3.0 T MRI study.

OBJECTIVES: We sought to prove feasibility of selective arterial infusion of superparamagnetic iron oxide (SPIO) particles in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: We studied 13 patients with HCC who underwent modified transarterial chemoembolization (TACE). Six patients received concurrent infusion of Ferucarbotran (Resovist, Schering, Berlin, Germany) in tumor-feeding arteries, and another 6 received MFL AS (MagForce, Nanotechnologies, Berlin, Germany). The iron content of both dispersions was 3.92 mg. One patient served as a control. All patients underwent magnetic resonance imaging (MRI) as baseline and immediate follow-up investigation. RESULTS: Selective arterial infusion of both SPIO particles resulted in significant intratumoral signal intensity decrease on T1-weighted sequences (P < 0.0001), which was greater after MagForce infusion compared with Resovist (P = 0.002). Only minimal amounts of dispersed particles were found in adjacent normal liver parenchyma. No change in intratumoral signal intensity was noted when ferromagnetic particles were omitted. CONCLUSIONS: Modified TACE with selective arterial infusion of SPIO particles can be used for precise tumor targeting in patients with HCC, for which MagForce appeared superior to Resovist.

Intrinsically radiopaque iodine-containing polyvinyl alcohol as a liquid embolic agent: evaluation in experimental wide-necked aneurysms.

OBJECT: To evaluate iodine-containing polyvinyl alcohol (I-PVA) as a precipitating liquid embolic agent, implant characteristics--including radiopacity, setting behavior, and biocompatibility--were studied in an aneurysm model in swine. METHODS: Twelve broad-based carotid artery (CA) sidewall aneurysms were surgically constructed in six pigs. Iodine-containing polyvinyl alcohol dissolved in dimethyl sulfoxide (DMSO) was injected during temporary balloon occlusion bridging the aneurysm neck. Control angiography as well as multidetector row computerized tomography (CT) angiography was performed after 4 weeks. Harvested aneurysms were investigated histopathologically and by 3-tesla high-field magnetic resonance (MR) imaging. The mean degree of aneurysm occlusion achieved was 96%. In two aneurysms a minimal protrusion of I-PVA into the CA lumen was observed. During one embolization, leakage of the liquid embolic agent due to DMSO-induced damage of the microcatheter resulted in CA occlusion. Aneurysms embolized with I-PVA could be discriminated clearly from the parent artery on CT angiograms because there was no beam-hardening artifact. High-field MR imaging allowed a detailed depiction of the liquid embolic distribution within the aneurysm. Histologically, a mild to moderate inflammatory response was found in successfully embolized aneurysms, and the polymer mass was frequently covered by a membrane of fibroblasts and endothelial cells. CONCLUSIONS: Iodine-containing polyvinyl alcohol is a ready-to-use liquid embolic agent clearly visible under fluoroscopy; additives are not required. The setting behavior allows for controlled delivery in aneurysm cavities. Histological studies performed 4 weeks after embolization revealed no sign of toxic tissue response to the liquid embolic agent. Overall, I-PVA exhibits interesting implant characteristics in that radiopaque admixtures are not necessary, thus allowing for artifact-free evaluation of treated aneurysms by using CT and MR angiography.

The effect of thermotherapy using magnetic nanoparticles on rat malignant glioma.

Thermotherapy using magnetic nanoparticles is a new technique for interstitial hyperthermia and thermoablation based on magnetic field-induced excitation of biocompatible superparamagnetic nanoparticles. To evaluate the potential of this technique for minimally invasive treatment, we carried out a systematic analysis of its effects on experimental glioblastoma multiforme in a rat tumor model. Tumors were induced by implantation of RG-2-cells into the brains of 120 male Fisher rats. Animals were randomly allocated to 10 groups of 12 rats each, including controls. Animals received two thermotherapy treatments following a single intratumoral injection of two different magnetic fluids (dextran- or aminosilane-coated iron-oxide nanoparticles). Treatment was carried out on days four and six after tumor induction using an alternating magnetic field applicator system operating at a frequency of 100 kHz and variable field strength of 0-18 kA/m. The effectiveness of treatment was determined by the survival time of the animals and histopathological examinations of the brain and the tumor.Thermotherapy with aminosilane-coated nanoparticles led up to 4.5-fold prolongation of survival over controls, while the dextran-coated particles did not indicate any advantage. Intratumoral deposition of the aminosilane-coated particles was found to be stable, allowing for serial thermotherapy treatments without repeated injection. Histological and immunohistochemical examinations after treatment revealed large necrotic areas close to particle deposits, a decreased proliferation rate and a reactive astrogliosis adjacent to the tumor.Thus, localized interstitial thermotherapy with magnetic nanoparticles has an antitumoral effect on malignant brain tumors. This method is suitable for clinical use and may be a novel strategy for treating malignant glioma, which cannot be treated successfully today. The optimal treatment schedules and potential combinations with other therapies need to be defined in further studies.

MRI of prostate cancer at 1.5 and 3.0 T: comparison of image quality in tumor detection and staging.

OBJECTIVE: This prospective study was performed to compare the image quality, tumor delineation, and depiction of staging criteria on MRI of prostate cancer at 1.5 and 3.0 T. SUBJECTS AND METHODS: Twenty-four patients with prostate cancer underwent MRI at 1.5 T using the combined endorectal-body phased-array coil and at 3.0 T using the torso phased-array coil, among them 22 before undergoing radical prostatectomy. The prostate was imaged with T2-weighted sequences in axial and coronal orientations at both field strengths and, in addition, with an axial T1-weighted sequence at 1.5 T. Preoperative analysis of all MR images taken together was compared with the histologic findings to determine the accuracy of MRI for the local staging of prostate cancer. In a retroanalysis, the image quality, tumor delineation, and conspicuity of staging criteria were determined separately for both field strengths and compared. Statistical analysis was performed using Wilcoxon's and the McNemar tests. RESULTS: In the preoperative analysis, MRI (at both 1.5 and 3.0 T) had an accuracy of 73% for the local staging of prostate cancer. The retroanalysis yielded significantly better results for 1.5-T MRI with the endorectal-body phased-array coil in terms of image quality (p < 0.001) and tumor delineation (p = 0.012) than for 3.0-T MRI with the torso phased-array coil. Analysis of the individual staging criteria for extracapsular disease did not reveal a superiority of either of the two field strengths in the depiction of any of the criteria. CONCLUSION: Intraindividual comparison shows that image quality and delineation of prostate cancer at 1.5 T with the use of an endorectal coil in a pelvic phased-array is superior to the higher field strength of 3.0 T with a torso phased-array coil alone. As long as no endorectal coil is available for 3-T imaging, imaging at 1.5 T using the combined endorectal-body phased-array coil will continue to be the gold standard for prostate imaging.

Efficacy of contrast medium use for neuroimaging at 3.0 T: utility of IR-FSE compared to other T1-weighted pulse sequences.

As inversion-recovery (IR) technique improves T1 contrast at high field strength, signal enhancement by T1-shortening contrast media may be affected. To clarify the different enhancement properties at 3.0 T, the authors compared T1-weighted sequences. Twelve contrast-enhancing lesions were investigated by spin-echo (SE), inversion recovery fast spin-echo (IR-FSE), two-dimensional gradient-echo (2D GE), and magnetization-prepared three-dimensional gradient-echo (3D GE) sequences and evaluated by comparing signal-intensity enhancements within the lesions. In addition, signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were measured. On average, signal enhancement of the lesions amounted to 60% for SE, 57% for IR-FSE, 32% for 2D GE, and 35% for 3D GE images. CNR of gray matter versus white matter was significantly higher for IR SE and GE imaging than for genuine SE and 2D GE acquisitions (Wilcoxon test), while 2D GE imaging alone had an excellent SNR. As IR-FSE images provide an excellent CNR for gray and white matter in the brain and contrast enhancement performs almost similarly well compared with SE imaging, this technique appears to be well suited for T1-weighted neuroimaging without and with contrast enhancement at 3.0 T. However, the inherent blurring of the IR-FSE can lead to poor performance for very small lesions.

Imaging of single human carcinoma cells in vitro using a clinical whole-body magnetic resonance scanner at 3.0 T.

The purpose of the present study was to examine whether single human carcinoma cells labeled with iron oxide nanoparticles could be detected by magnetic resonance (MR) imaging on a clinical 3-T scanner using a surface coil only. WiDr human colon carcinoma cells were loaded with two kinds of iron oxide nanoparticles differing by coating and size: aminosilan-coated (MagForce) and carboxy-dextran-coated particles (Resovist). The latter were preferred by the colon carcinoma cell line used here and taken up much faster (12 h) than the smaller carboxydextran-coated Resovist (48 h). Labeled single carcinoma cells, distributed in an agarose gel in a monodisperse layer as controlled by light microscopy, became detectable as punctuate signal extinctions when using a small circularly polarized surface coil in conjunction with a T(2)*-weighted GE sequence at 3 T. The threshold for the detectability of labeled colon carcinoma cells ranged at a load of 4-5 mug iron/10(6) cells. Obviating the need for special hardware additions, this study opens a new lane for single-cell tracking on clinical 3-T MR scanners amenable to patient studies.

123I-IMT SPECT and 1H MR-spectroscopy at 3.0 T in the differential diagnosis of recurrent or residual gliomas: a comparative study.

The aim of this investigation was to compare two current non-invasive modalities, single photon emission tomography (SPECT) using 123-iodine-alpha-methyl tyrosine (123I-IMT) and single-voxel proton magnetic resonance spectroscopy (1H-MRS) at 3.0 T, with regard to their ability to differentiate between residual/ recurrent tumors and treatment-related changes in patients pretreated for glioma. The patient population comprised 25 patients in whom recurrent glioma was suspected based on MR imaging. SPECT imaging started 10 min after iv. injection of 300-370 MBq 123I-IMT and was performed using a triple-head system. The IMT uptake was calculated semiquantitatively using regions-of-interest. 1H-MRS was performed at 3.0 T using the single-volume point-resolved spectroscopy (PRESS) technique. Guided by MR imaging volumes-of-interest for spectroscopy were placed into the suspected lesions. Signal intensities of choline-containing compounds (Cho), creatine and phosphocreatine (Cr), and N-acetylaspartate (NAA) were obtained. When using the cut-off of 1.62 for 123I-IMT uptake, the sensitivity, specificity, and accuracy of the 123I-IMT SPECT were 95, 100 and 96%, respectively. For 1H-MRS, the sensitivity, specificity and accuracy were 89, 83 and 88%, respectively, based both on the metabolic ratios of Cho/Cr and Cho/NAA as tumor criterion with cut-off values of 1.11 and 1.17, respectively. In conclusion, 123I-IMT SPECT yielded more favorable results compared to 1H-MRS at distinguishing recurrent and/or residual glioma from post-therapeutic changes and may be particularly valuable when the evaluation of tumor extent is necessary.