Hemodynamic nature of black-blood enhancement in long-term coiled cerebral aneurysms

PURPOSE

Vessel wall imaging (VWI) with black-blood (BB) technique can demonstrate aneurysmal enhancement preluding to growth/rupture in treatment-naive cerebral aneurysms. Interestingly, recent works showed that BB enhancement may also occur in endovascularly treated aneurysms, though its meaning is controversial. Hypothesizing a flow-related mechanism of BB enhancement, we explored its relationship with incomplete occlusion status and coil packing density at DSA.

METHODS

We analyzed the subjects undergoing 3T MRI between January 2017 and October 2020 for a previous aneurysmal coiling. All the MRI studies included pre- and post-contrast 3D BB sequences. The presence of intra-aneurysmal pre-contrast BB signal was assessed. BB enhancement (when present) was classified as follows: (1) enhancement at the neck, (2) intrasaccular/intra-coil enhancement, and (3) peripheral enhancement. Coil packing density and aneurysmal occlusion status (according to the modified Raymond-Roy classification, MRRC) were determined on post-treatment DSA and compared with BB findings using generalized linear mixed-effect model and ANOVA. Significant p values were <0.05.

RESULTS

Forty-eight aneurysms from 44 patients were eligible for analysis. Pre-contrast BB signal was observed in 50% of the aneurysms and showed a relationship with baseline aneurysmal size. BB enhancement was detectable in 31 aneurysms (65%), being significantly associated with incomplete aneurysmal occlusion and reduced coil packing density at DSA.

CONCLUSION

BB enhancement of coiled aneurysms is related with increasing degrees of post-coiling aneurysmal remnants and with loose coil packing density at DSA. This supports a hemodynamic interpretation of BB enhancement in long-term coiled aneurysms.

Comparison between inferior frontal gyrus intrinsic connectivity network and verb-generation task fMRI network for presurgical language mapping in healthy controls and in glioma patients

Task-based functional MRI (tb-fMRI) represents an extremely valuable approach for the identification of language eloquent regions for presurgical mapping in patients with brain tumors. However, its routinely application is limited by patient-related factors, such as cognitive disability and difficulty in coping with long-time acquisitions, and by technical factors, such as lack of equipment availability for stimuli delivery. Resting-state fMRI (rs-fMRI) instead, allows the identification of distinct language networks in a 10-min acquisition without the need of performing active tasks and using specific equipment. Therefore, to test the feasibility of rs-fMRI as a preoperative mapping tool, we reconstructed a lexico-semantic intrinsic connectivity network (ICN) in healthy controls (HC) and in a case series of patients with gliomas and compared the organization of this language network with the one derived from tb-fMRI in the patient's group. We studied three patients with extra-frontal gliomas who underwent functional mapping with auditory verb-generation (AVG) task and rs-fMRI with a seed in the left inferior frontal gyrus (IFG). First, we identified the functional connected areas to the IFG in HC. We qualitatively compared these areas with those that showed functional activation in AVG task derived from Neurosynth meta-analysis. Last, in each patient we performed single-subject analyses both for rs- and tb-fMRI, and we evaluated the spatial overlap between the two approaches. In HC, the IFG-ICN network showed a predominant left fronto-temporal functional connectivity in regions overlapping with the AVG network derived from a meta-analysis. In two patients, rs- and tb-fMRI showed comparable patterns of activation in left fronto-temporal regions, with different levels of contralateral activations. The third patient could not accomplish the AVG task and thus it was not possible to make any comparison with the ICN. However, in this patient, task-free approach disclosed a consistent network of fronto-temporal regions as in HC, and additional parietal regions. Our preliminary findings support the value of rs-fMRI approach for presurgical mapping, particularly for identifying left fronto-temporal core language-related areas in glioma patients. In a preoperative setting, rs-fMRI approach could represent a powerful tool for the identification of eloquent language areas, especially in patients with language or cognitive impairments.

Multiple hypointense veins on susceptibility weighted imaging as a promising biomarker of impaired cerebral hemodynamics in chronic steno-occlusive disease: a multiparametric MRI study

PURPOSE

Patients with steno-occlusive arterial disease may develop cerebral hypoperfusion with possible neurologic sequelae. The aim of the study is to verify the possible role of SWI, as a marker of cerebral hypoperfusion, in the identification of patient subgroups with significant chronic occlusions/stenoses at risk of critical cerebral hypoperfusion.

METHODS

We retrospectively identified 37 asymptomatic patients with chronic intra-extracranial occlusion/stenosis of the anterior circulation from a prospective brain MRI register between 2016 and 2020. All patients underwent 3 Tesla MRI. The imaging protocol included the following: SWI, 3D-FLAIR, DWI sequences, and 3D-TOF MRA. SWI findings were graded for the presence of asymmetric intracranial cortical veins (grades 1 to 4). The presence of collateralization was assessed with concomitant multiphase-CTA. FLAIR was evaluated for the presence of distal hyperintense vessels (DHVs), a described marker of flow impairment, and possible collateralization. Cerebral blood flow and arterial transit artifacts (ATAs) were evaluated at pCASL in 29 patients.

RESULTS

SWI showed multiple hypointense vessels (MHVs) in 22/37 patients in the cerebral hemisphere ipsilateral to vessel occlusion/stenosis. SWI-MHV grade 1 was found in 15 patients (40.5%), grade 2 in 18 patients (48.7%), and grade 3 in 3 patients (8.1%); in one patient, SWI was graded as 4 (2.7%). A significant relationship was found among MHV, DHV, collaterals, ATAs, and hypoperfused areas on pCASL and with patients' previous neurological symptoms.

CONCLUSION

SWI-MVH correlates with chronic cerebral flow impairment and is related to hypoperfusion and collateralization. It may help identify a subgroup of patients benefitting from revascularization.

Left ventricular myocardial work indices and invasive measurement of stroke work: a correlation study

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND

A novel echocardiographic method allows to non-invasively assess myocardial work using pressure-strain loops. Even though left ventricular myocardial work has already emerged as a promising prognostic tool for various pathological conditions, its relationship with invasively-derived corresponding indices has not been assessed in humans yet.

PURPOSE

This study aimed to explore the correlation between left ventricular myocardial work (LVMW) indices and invasively-derived left ventricular stroke work index (LVSWI) in a cohort of patients with advanced heart failure (HF) considered for heart transplantation.

METHODS

All consecutive patients with advanced heart failure considered for heart transplantation from 2016 to 2021 that had already performed right heart catheterization (RHC) as part of the workup and with an available echocardiographic exam were included (n = 91). Myocardial work analysis was performed in 44 patients, according to exclusion criteria. Conventional LV functional parameters and LVMW indices, including LV global work index (LVGWI), LV global constructive work (LVGCW), LV global wasted work (LVGWW), LV global work efficiency (LVGWE) and other were calculated and compared with invasively measured LV stroke work index (LVSWI).

RESULTS

Median time between RHC and echocardiography was 0 months [interquartile range (IQR): 0 – 1]. Median age was 60 years (IQR: 54 – 63). For the most part, etiology of HF was non-ischemic (61.4%) and all patients were either on class NYHA II (61.4%) or III (27.3%). Median left ventricular ejection fraction was 25% (IQR: 22.3 – 32.3), median NT-proBNP 1377 pg/mL (IQR: 646 – 2570). Among conventional parameters of LV function, LV global longitudinal strain (LVGLS) significantly correlated with LVSWI (r = - 0.337; p = 0.031), whereas LVEF did not (r = 0.308; p = 0.050). With regard to LVMW indices, some of them demonstrated correlation with LVSWI, particularly LVGWI (r = 0.425; p = 0.006), LVGCW (r = 0.506; p = 0.001), LV global positive work (LVGPW; r = 0.464; p = 0.003) and LV global systolic constructive work (LVGSCW; r = 0.471; p = 0.002).

CONCLUSIONS

Among left ventricular myocardial work indices, LVGCW correlated better with invasively-derived stroke work, thus representing a powerful and reliable tool for a more comprehensive evaluation of myocardial function. Abstract Figure. Study flow chart  Abstract Figure. Correlation results

How to deal with low-flow low-gradient aortic stenosis and reduced left ventricle ejection fraction: from literature review to tips for clinical practice

Low-flow low-gradient aortic stenosis (LFLG AS) with reduced left ventricle ejection fraction (LVEF) is still a diagnostic and therapeutic challenge. The aim of this paper is to review the latest evidences about the assessment of the valvular disease, usually difficult because of the low-flow status, and the therapeutic options. Special emphasis is given to the available diagnostic tools for the characterization of LFLG AS without functional reserve at stress echocardiography and to the factors that clinicians should evaluate to choose between surgical aortic valve repair, transcatheter aortic valve implantation, or medical therapy.

Along-tract statistics of neurite orientation dispersion and density imaging diffusion metrics to enhance MR tractography quantitative analysis in healthy controls and in patients with brain tumors

Along‐tract statistics analysis enables the extraction of quantitative diffusion metrics along specific white matter fiber tracts. Besides quantitative metrics derived from classical diffusion tensor imaging (DTI), such as fractional anisotropy and diffusivities, new parameters reflecting the relative contribution of different diffusion compartments in the tissue can be estimated through advanced diffusion MRI methods as neurite orientation dispersion and density imaging (NODDI), leading to a more specific microstructural characterization. In this study, we extracted both DTI‐ and NODDI‐derived quantitative microstructural diffusion metrics along the most eloquent fiber tracts in 15 healthy subjects and in 22 patients with brain tumors. We obtained a robust intraprotocol reference database of normative along‐tract microstructural metrics, and their corresponding plots, from healthy fiber tracts. Each diffusion metric of individual patient's fiber tract was then plotted and statistically compared to the normative profile of the corresponding metric from the healthy fiber tracts. NODDI‐derived metrics appeared to account for the pathological microstructural changes of the peritumoral tissue more accurately than DTI‐derived ones. This approach may be useful for future studies that may compare healthy subjects to patients diagnosed with other pathological conditions.

Diagnostic efficacy and safety of gadoteridol compared to gadobutrol and gadoteric acid in a large sample of CNS MRI studies at 1.5T

PURPOSE

To evaluate safety and diagnostic accuracy of gadoteridol vs. other macrocyclic gadolinium-based contrast agents (GBCAs) in a large cohort of consecutive and non-selected patients referred for CE-MRI of the CNS.

MATERIAL AND METHODS

Between November 2017 and March 2018, we prospectively enrolled a consecutive cohort of patients referred for neuroradiological CE-MRI (1.5T MRI). Image quality and adverse events were assessed. Diagnostic performance was determined for a subgroup of patients with truth standard findings available. Comparison was made between patients receiving gadoteridol and patients receiving other macrocyclic GBCAs. Inter-reader agreement (kappa) between two expert neuroradiologists was calculated for the diagnosis of malignancy.

RESULTS

Overall, 460 patients (220M/240F; mean age 54±16 years) were enrolled of which 230 received gadoteridol (Group 1) and 230 either gadoteric acid or gadobutrol [n=83 (36.1%) and n=147 (63.9%), respectively; Group 2]. Image quality was rated as good or excellent in both groups. The sensitivity, specificity and diagnostic accuracy for determination of malignancy was 88.2%, 96.5% and 95.4%, respectively, for Group 1 and 93.7%, 97.4% and 96.9%, respectively, for Group 2, with no significant differences between groups (P>0.75) for any determination. Inter-reader agreement for the identification of malignancy was excellent [K=0.877 (95%CI: 0.758-0.995) and K=0.818 (95%CI: 0.663-0.972) for groups 1 and 2, respectively; P=0.0913]. Adverse events occurred in 5 of 460 (1.09%) patients overall, with no significant difference (P=0.972) between groups.

CONCLUSION

Gadoteridol was safe and guaranteed good image quality without significant differences when compared to gadobutrol and gadoteric acid in a wide range of CNS pathologies.

Subcortico-Cortical Functional Connectivity in the Fetal Brain: A Cognitive Development Blueprint

Recent evidence has shown that patterns of cortico-cortical functional synchronization are consistently traceable by the end of the third trimester of pregnancy. The involvement of subcortical structures in early functional and cognitive development has never been explicitly investigated, notwithstanding their pivotal role in different cognitive processes. We address this issue by exploring subcortico-cortical functional connectivity at rest in a group of normally developing fetuses between the 25th and 32nd weeks of gestation. Results show significant functional coupling between subcortical nuclei and cortical networks related to: (i) sensorimotor processing, (ii) decision making, and (iii) learning capabilities. This functional maturation framework unearths a Cognitive Development Blueprint, according to which grounding cognitive skills are planned to develop with higher ontogenetic priority. Specifically, our evidence suggests that a newborn already possesses the ability to: (i) perceive the world and interact with it, (ii) create salient representations for the selection of adaptive behaviors, and (iii) store, retrieve, and evaluate the outcomes of interactions, in order to gradually improve adaptation to the extrauterine environment.

fMRI-Targeted High-Angular Resolution Diffusion MR Tractography to Identify Functional Language Tracts in Healthy Controls and Glioma Patients

BACKGROUND

MR Tractography enables non-invasive preoperative depiction of language subcortical tracts, which is crucial for the presurgical work-up of brain tumors; however, it cannot evaluate the exact function of the fibers.

PURPOSE

A systematic pipeline was developed to combine tractography reconstruction of language fiber bundles, based on anatomical landmarks (Anatomical-T), with language fMRI cortical activations. A fMRI-targeted Tractography (fMRI-T) was thus obtained, depicting the subsets of the anatomical tracts whose endpoints are located inside a fMRI activation. We hypothesized that fMRI-T could provide additional functional information regarding the subcortical structures, better reflecting the eloquent white matter structures identified intraoperatively.

METHODS

Both Anatomical-T and fMRI-T of language fiber tracts were performed on 16 controls and preoperatively on 16 patients with left-hemisphere brain tumors, using a q-ball residual bootstrap algorithm based on High Angular Resolution Diffusion Imaging (HARDI) datasets (b = 3000 s/mm2; 60 directions); fMRI ROIs were obtained using picture naming, verbal fluency, and auditory verb generation tasks. In healthy controls, normalized MNI atlases of fMRI-T and Anatomical-T were obtained. In patients, the surgical resection of the tumor was pursued by identifying eloquent structures with intraoperative direct electrical stimulation mapping and extending surgery to the functional boundaries. Post-surgical MRI allowed to identify Anatomical-T and fMRI-T non-eloquent portions removed during the procedure.

RESULTS

MNI Atlases showed that fMRI-T is a subset of Anatomical-T, and that different task-specific fMRI-T involve both shared subsets and task-specific subsets - e.g., verbal fluency fMRI-T strongly involves dorsal frontal tracts, consistently with the phonogical-articulatory features of this task. A quantitative analysis in patients revealed that Anatomical-T removed portions of AF-SLF and IFOF were significantly greater than verbal fluency fMRI-T ones, suggesting that fMRI-T is a more specific approach. In addition, qualitative analyses showed that fMRI-T AF-SLF and IFOF predict the exact functional limits of resection with increased specificity when compared to Anatomical-T counterparts, especially the superior frontal portion of IFOF, in a subcohort of patients.

CONCLUSION

These results suggest that performing fMRI-T in addition to the 'classic' Anatomical-T may be useful in a preoperative setting to identify the 'high-risk subsets' that should be spared during the surgical procedure.

Reproducibility of dynamic contrast-enhanced MRI and dynamic susceptibility contrast MRI in the study of brain gliomas: a comparison of data obtained using different commercial software

PURPOSE

Dynamic susceptibility contrast MRI (DSC) and dynamic contrast-enhanced MRI (DCE) are useful tools in the diagnosis and follow-up of brain gliomas; nevertheless, both techniques leave the open issue of data reproducibility. We evaluated the reproducibility of data obtained using two different commercial software for perfusion maps calculation and analysis, as one of the potential sources of variability can be the software itself.

METHODS

DSC and DCE analyses from 20 patients with gliomas were tested for both the intrasoftware (as intraobserver and interobserver reproducibility) and the intersoftware reproducibility, as well as the impact of different postprocessing choices [vascular input function (VIF) selection and deconvolution algorithms] on the quantification of perfusion biomarkers plasma volume (Vp), volume transfer constant (K ^trans) and rCBV. Data reproducibility was evaluated with the intraclass correlation coefficient (ICC) and Bland-Altman analysis.

RESULTS

For all the biomarkers, the intra- and interobserver reproducibility resulted in almost perfect agreement in each software, whereas for the intersoftware reproducibility the value ranged from 0.311 to 0.577, suggesting fair to moderate agreement; Bland-Altman analysis showed high dispersion of data, thus confirming these findings. Comparisons of different VIF estimation methods for DCE biomarkers resulted in ICC of 0.636 for K ^trans and 0.662 for Vp; comparison of two deconvolution algorithms in DSC resulted in an ICC of 0.999.

CONCLUSIONS

The use of single software ensures very good intraobserver and interobservers reproducibility. Caution should be taken when comparing data obtained using different software or different postprocessing within the same software, as reproducibility is not guaranteed anymore.

Longitudinal MRI quantification of muscle degeneration in Duchenne muscular dystrophy

OBJECTIVE

The aim of this study was to evaluate the usefulness of magnetic resonance imaging (MRI) in detecting the progression of Duchenne muscular dystrophy (DMD) by quantification of fat infiltration (FI) and muscle volume index (MVI, a residual-to-total muscle volume ratio).

METHODS

Twenty-six patients (baseline age: 5-12 years) with genetically proven DMD were longitudinally analyzed with lower limb 3T MRI, force measurements, and functional tests (Gowers, 10-m time, North Star Ambulatory Assessment, 6-min walking test). Five age-matched controls were also examined, with a total of 85 MRI studies. Semiquantitative (scores) and quantitative MRI (qMRI) analyses (signal intensity ratio - SIR, lower limb MVI, and individual muscle MVI) were carried out. Permutation and regression analyses according to both age and functional test-outcomes were calculated. Age-related quantitative reference curves of SIRs and MVIs were generated.

RESULTS

FI was present on glutei and adductor magnus in all patients since the age of 5, with a proximal-to-distal progression and selective sparing of sartorius and gracilis. Patients' qMRI measures were significantly different from controls' and among age classes. qMRI were more sensitive than force measurements and functional tests in assessing disease progression, allowing quantification also after loss of ambulation. Age-related curves with percentile values were calculated for SIRs and MVIs, to provide a reference background for future experimental therapy trials. SIRs and MVIs significantly correlated with all clinical measures, and could reliably predict functional outcomes and loss of ambulation.

INTERPRETATIONS

qMRI-based indexes are sensitive measures that can track the progression of DMD and represent a valuable tool for follow-up and clinical studies.

Interference and conflict monitoring in individuals with amnestic mild cognitive impairment: A structural study of the anterior cingulate cortex

Amnestic mild cognitive impairment (aMCI) is a clinical condition characterized by memory impairment in the absence of any other cognitive impairment and is commonly associated with high conversion to Alzheimer's disease. Recent evidence shows that executive functions and selective attention mechanisms could also be impaired in aMCI. In this study, we investigated performance differences (i.e., reaction times [RTs] and accuracy) between a group of aMCI participants and a group of age-matched healthy individuals on the attentional network task (ANT) focusing on situations with increased interference. In particular, we assessed the relationship between interference and conflict effects and grey matter volumes (GMVs) of the anterior cingulate cortex (ACC)/pre-supplementary motor area in the entire sample because of its crucial role in conflict monitoring. When compared with controls, aMCI participants were less accurate on the ANT, showing increased interference and conflict effects, but no differences in RTs. In addition, aMCI participants exhibited lower GMV in the ACC than controls. While better accuracy for interference and conflict effects was associated with an increase of GMV in the ACC for both groups, RTs from the interference effect were negatively correlated with GMV of the ACC only in aMCI participants. In other words, lower GMV values of the ACC were paralleled with significantly impaired performance in terms of interference resolution. In conclusion, our study suggests the presence of a selective impairment in interference and conflict monitoring in aMCI, which in turn is associated with decreased GMVs in the ACC.

Dynamic contrast-enhanced and dynamic susceptibility contrast perfusion MR imaging for glioma grading: Preliminary comparison of vessel compartment and permeability parameters using hotspot and histogram analysis

INTRODUCTION

Dynamic susceptibility contrast (DSC)-MRI is a perfusion technique with high diagnostic accuracy for glioma grading, despite limitations due to inherent susceptibility effects. Dynamic contrast-enhanced (DCE)-MRI has been proposed as an alternative technique able to overcome the DSC-MRI shortcomings. This pilot study aimed at comparing the diagnostic accuracy of DSC and DCE-MRI for glioma grading by evaluating two estimates of blood volume, the DCE-derived plasma volume (Vp) and the DSC-derived relative cerebral blood volume (rCBV), and a measure of vessel permeability, the DCE-derived volume transfer constant K(trans).

METHODS

Twenty-six newly diagnosed glioma patients underwent 3T-MR DCE and DSC imaging. Parametric maps of CBV, Vp and K(trans) were calculated and the region of highest value (hotspot) was measured on each map. Histograms of rCBV, Vp and K(trans) values were calculated for the tumor volume. Statistical differences according to WHO grade were assessed. The diagnostic accuracy for tumor grading of the two techniques was determined by ROC analysis.

RESULTS

rCBV, Vp and K(trans) measures differed significantly between high and low-grade gliomas. Hotspot analysis showed the highest correlation with grading. K(trans) hotspots co-localized with Vp hotspots only in 56% of enhancing gliomas. For differentiating high from low-grade gliomas the AUC was 0.987 for rCBVmax, and 1.000 for Vpmax and K(trans)max. Combination of DCE-derived Vp and K(trans) parameters improved the diagnostic performance of the histogram method.

CONCLUSION

This initial experience of DCE-derived Vp evaluation shows that this parameter is as accurate as the well-established DSC-derived rCBV for glioma grading. DCE-derived K(trans) is equally useful for grading, providing different informations with respect to Vp.

Evaluation of low-grade glioma structural changes after chemotherapy using DTI-based histogram analysis and functional diffusion maps

OBJECTIVES

To explore the role of diffusion tensor imaging (DTI)-based histogram analysis and functional diffusion maps (fDMs) in evaluating structural changes of low-grade gliomas (LGGs) receiving temozolomide (TMZ) chemotherapy.

METHODS

Twenty-one LGG patients underwent 3T-MR examinations before and after three and six cycles of dose-dense TMZ, including 3D-fluid-attenuated inversion recovery (FLAIR) sequences and DTI (b = 1000 s/mm(2), 32 directions). Mean diffusivity (MD), fractional anisotropy (FA), and tensor-decomposition DTI maps (p and q) were obtained. Histogram and fDM analyses were performed on co-registered baseline and post-chemotherapy maps. DTI changes were compared with modifications of tumour area and volume [according to Response Assessment in Neuro-Oncology (RANO) criteria], and seizure response.

RESULTS

After three cycles of TMZ, 20/21 patients were stable according to RANO criteria, but DTI changes were observed in all patients (Wilcoxon test, P ≤ 0.03). After six cycles, DTI changes were more pronounced (P ≤ 0.005). Seventy-five percent of patients had early seizure response with significant improvement of DTI values, maintaining stability on FLAIR. Early changes of the 25th percentiles of p and MD predicted final volume change (R(2) = 0.614 and 0.561, P < 0.0005, respectively). TMZ-related changes were located mainly at tumour borders on p and MD fDMs.

CONCLUSIONS

DTI-based histogram and fDM analyses are useful techniques to evaluate the early effects of TMZ chemotherapy in LGG patients.

KEY POINTS

• DTI helps to assess the efficacy of chemotherapy in low-grade gliomas. • Histogram analysis of DTI metrics quantifies structural changes in tumour tissue. • Functional diffusion maps (fDMs) spatially localize the changes of DTI metrics. • Changes in DTI histograms and fDMs precede changes in conventional MRI. • Early changes in DTI histograms and fDMs correlate with seizure response.

Functional correlates of preserved naming performance in amnestic Mild Cognitive Impairment

Naming abilities are typically preserved in amnestic Mild Cognitive Impairment (aMCI), a condition associated with increased risk of progression to Alzheimer's disease (AD). We compared the functional correlates of covert picture naming and word reading between a group of aMCI subjects and matched controls. Unimpaired picture naming performance was associated with more extensive activations, in particular involving the parietal lobes, in the aMCI group. In addition, in the condition associated with higher processing demands (blocks of categorically homogeneous items, living items), increased activity was observed in the aMCI group, in particular in the left fusiform gyrus. Graph analysis provided further evidence of increased modularity and reduced integration for the homogenous sets in the aMCI group. The functional modifications associated with preserved performance may reflect, in the case of more demanding tasks, compensatory mechanisms for the subclinical involvement of semantic processing areas by AD pathology.

The mirror neuron system and the strange case of Broca's area

Mirror neurons, originally described in the monkey premotor area F5, are embedded in a frontoparietal network for action execution and observation. A similar Mirror Neuron System (MNS) exists in humans, including precentral gyrus, inferior parietal lobule, and superior temporal sulcus. Controversial is the inclusion of Broca's area, as homologous to F5, a relevant issue in light of the mirror hypothesis of language evolution, which postulates a key role of Broca's area in action/speech perception/production. We assess "mirror" properties of this area by combining neuroimaging and intraoperative neurophysiological techniques. Our results show that Broca's area is minimally involved in action observation and has no motor output on hand or phonoarticulatory muscles, challenging its inclusion in the MNS. The presence of these functions in premotor BA6 makes this area the likely homologue of F5 suggesting that the MNS may be involved in the representation of articulatory rather than semantic components of speech.

White matter integrity in obstructive sleep apnea before and after treatment

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is commonly associated with cognitive and functional deficits, some of which are resolved after continuous positive airway pressure (CPAP) treatment. The investigation of brain structural changes before and after treatment could provide deep insights into the pathogenesis and the reversibility of this disorder. We hypothesized that severe OSA patients would have altered white matter (WM) integrity and cognition and that treatment would improve both the structural damage and the cognitive impairment.

DESIGN

Prospective clinical study.

SETTING

The Sleep Disorders Center and the Center of Excellence in High-Field Magnetic Resonance Imaging at Vita-Salute San Raffaele University, Milan, Italy.

PARTICIPANTS

Seventeen never-treated consecutive OSA patients were evaluated before and after treatment (after 3 and 12 months) and compared to 15 matched healthy controls.

INTERVENTION

CPAP.

MEASUREMENTS

WM integrity measured by diffusion tensor imaging (DTI) and cognitive performance (measured with neuropsychological testing) before and after 3 and 12 months of CPAP.

RESULTS

Results in pre-treatment OSA patients showed impairments in most cognitive areas, mood and sleepiness that were associated with diffuse reduction of WM fiber integrity reflected by diminished fractional anisotropy (FA) and mean diffusivity (MD) in multiple brain areas. After 3 months of CPAP, only limited changes of WM were found. However, over the course of 12 months CPAP treatment, an almost complete reversal of WM abnormalities in all the affected regions was observed in patients who were compliant with treatment. Significant improvements involving memory, attention, and executive-functioning paralleled WM changes after treatment.

CONCLUSIONS

Changes of WM DTI "signatures" of brain pathology in OSA patients are appreciable over the course of 12-month treatment with CPAP in most of the regions involved. Recovery of cognitive deficits after treatment is consistent with the presence of a reversible structural neural injury in OSA in patients who were compliant with treatment.

Comparison of 3D TOF-MRA and 3D CE-MRA at 3T for imaging of intracranial aneurysms

PURPOSE

To compare 3T elliptical-centric CE MRA with 3T TOF MRA for the detection and characterization of unruptured intracranial aneurysms (UIAs), by using digital subtracted angiography (DSA) as reference.

MATERIALS AND METHODS

Twenty-nine patients (12 male, 17 female; mean age: 62 years) with 41 aneurysms (34 saccular, 7 fusiform; mean diameter: 8.85 mm [range 2.0-26.4mm]) were evaluated with MRA at 3T each underwent 3D TOF-MRA examination without contrast and then a 3D contrast-enhanced (CE-MRA) examination with 0.1mmol/kg bodyweight gadobenate dimeglumine and k-space elliptic mapping (Contrast ENhanced Timing Robust Angiography [CENTRA]). Both TOF and CE-MRA images were used to evaluate morphologic features that impact the risk of rupture and the selection of a treatment. Almost half (20/41) of UIAs were located in the internal carotid artery, 7 in the anterior communicating artery, 9 in the middle cerebral artery and 4 in the vertebro-basilar arterial system. All patients also underwent DSA before or after the MR examination.

RESULTS

The CE-MRA results were in all cases consistent with the DSA dataset. No differences were noted between 3D TOF-MRA and CE-MRA concerning the detection and location of the 41 aneurysms or visualization of the parental artery. Differences were apparent concerning the visualization of morphologic features, especially for large aneurysms (>13 mm). An irregular sac shape was demonstrated for 21 aneurysms on CE-MRA but only 13/21 aneurysms on 3D TOF-MRA. Likewise, CE-MRA permitted visualization of an aneurismal neck and calculation of the sac/neck ratio for all 34 aneurysms with a neck demonstrated at DSA. Conversely, a neck was visible for only 24/34 aneurysms at 3D TOF-MRA. 3D CE-MRA detected 15 aneurysms with branches originating from the sac and/or neck, whereas branches were recognized in only 12/15 aneurysms at 3D TOF-MRA.

CONCLUSION

For evaluation of intracranial aneurysms at 3T, 3D CE-MRA is superior to 3D TOF-MRA for assessment of sac shape, detection of aneurysmal neck, and visualization of branches originating from the sac or neck itself, if the size of the aneurysm is greater than 13 mm. 3T 3D CE-MRA is as accurate and effective as DSA for the evaluation of UIAs.

Monolateral type I proatlantal artery with bilateral absence of vertebral arteries: description of a case and review of the literature

We report a case of a patient with right type I proatlantal intersegmental artery associated with right fetal posterior cerebral artery and absence of both vertebral arteries and of the left posterior communicating artery. We also describe the clinical relevance of these findings for this patient. A 56-year-old woman with vertigo and tinnitus underwent contrast enhanced Magnetic Resonance Angiography (MRA) of the supra-aortic arteries using a 1.5 Tesla scanner. Maximum intensity projection and volume rendering reconstructions were obtained. MRA demonstrated the persistence of an anastomotic artery between the right internal carotid artery and basilar artery, passing through the foramen magnum, suggesting a type I proatlantal intersegmental artery. The examination also showed the absence of both vertebral arteries and the presence of a right fetal-type posterior cerebral artery. To our knowledge, this is the first report of a type I proatlantal intersegmental artery associated with an omolateral fetal-type posterior cerebral artery and the absence of both vertebral arteries and of the left posterior communicating artery. This condition requires a watchful monitoring of the patient and has to be considered in case of surgical procedures of the carotid arteries.

Role of diffusion tensor magnetic resonance tractography in predicting the extent of resection in glioma surgery

Diffusion tensor imaging (DTI) tractography enables the in vivo visualization of the course of white matter tracts inside or around a tumor, and it provides the surgeon with important information in resection planning. This study is aimed at assessing the ability of preoperative DTI tractography in predicting the extent of the resection achievable in surgical removal of gliomas. Patients with low-grade gliomas (LGGs; 46) and high-grade gliomas (HGGs; 27) were studied using a 3T scanner according to a protocol including a morphological study (T2, fluid-attenuated inversion-recovery, T1 sequences) and DTI acquisitions (b = 1000 s/mm(2), 32 gradient directions). Preoperative tractography was performed off-line on the basis of a streamline algorithm, by reconstructing the inferior fronto-occipital (IFO), the superior longitudinal fascicle (SLF), and the corticospinal tract (CST). For each patient, the relationship between each bundle reconstructed and the lesion was analyzed. Initial and residual tumor volumes were measured on preoperative and postoperative 3D fluid-attenuated inversion-recovery images for LGGs and postcontrast T1-weighted scans for HGGs. The presence of intact fascicles was predictive of a better surgical outcome, because these cases showed a higher probability of total resection than did subtotal and partial resection. The presence of infiltrated or displaced CST or infiltrated IFO was predictive of a lower probability of total resection, especially for tumors with preoperative volume <100 cm(3). DTI tractography can thus be considered to be a promising tool for estimating preoperatively the degree of radicality to be reached by surgical resection. This information will aid clinicians in identifying patients who will mostly benefit from surgery.

Ocular adnexal lymphoma: diffusion-weighted mr imaging for differential diagnosis and therapeutic monitoring

PURPOSE

To describe the magnetic resonance (MR) imaging and diffusion-weighted (DW) imaging features of ocular adnexal lymphomas (OALs), to determine the diagnostic accuracy of apparent diffusion coefficient (ADC) for discriminating OALs from other orbital mass lesions, and to assess whether variations in ADC constitute a reliable biomarker of OAL response to therapy.

MATERIALS AND METHODS

Institutional ethical committee approval and informed consent were obtained. In this prospective study, 114 white subjects (65 females and 49 males) were enrolled. Thirty-eight patients with histopathologically proved OAL underwent serial MR and DW imaging examination of the orbits. ADCs of OALs were compared with those of normal orbital structures, obtained in 18 healthy volunteers, and other orbital mass lesions, prospectively acquired in 58 patients (20 primary non-OAL neoplasms, 15 vascular benign lesions, 12 inflammatory lesions, 11 metastases). Interval change in ADC of OALs before and after treatment was analyzed in 29 patients. Analysis of covariance and a paired t test were used for statistical analysis.

RESULTS

Baseline ADCs in OALs were lower than those in normal structures and other orbital diseases (P < .001). An ADC threshold of 775 x 10(-6) mm(2)/sec resulted in 96% sensitivity, 93% specificity, 88% positive predictive value, 98.2% negative predictive value, and 94.4% accuracy in OAL diagnosis. Following appropriate treatment, 10 (34%) of 29 patients showed OAL volumetric reduction, accompanied (n = 7) or preceded (n = 3) by an increase in ADC (P = .005). Conversely, a further reduction of ADC was observed in the seven patients who experienced disease progression (P < .05).

CONCLUSION

ADC permits accurate diagnosis of OALs. Interval change in ADC after therapy represents a helpful tool for predicting therapeutic response.

Brain activation changes before and after PAP treatment in obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea syndrome (OSAS) is associated with cognitive and functional deficits, most of which are corrected after positive airway pressure (PAP) treatment. Previous studies investigating the neural underpinnings of OSAS failed to provide consistent results both on the cerebral substrates underlying cognitive deficits and on the effect of treatment on these anomalies. The aims of the study were a) to investigate whether never-treated OSA patients demonstrated differences in brain activation compared to healthy controls during a cognitive task; and b) to investigate whether any improvements in cognitive functioning found in OSA patients after treatment reflected a change in the underlying cerebral activity.

DESIGN

OSA patients and healthy controls underwent functional magnetic resonance imaging (fMRI) scanning. They were compared on performance and brain activation during a 2-back working-memory task. Patients were also re-evaluated after 3 months treatment with PAP. Cognitive functions were evaluated using neurocognitive tests. Sleepiness (ESS), mood (Beck Depression Inventory) and, quality-of-life (SF-36) were also assessed.

SETTING

The Sleep Disorders Center and CERMAC at the Vita-Salute San Raffaele University.

PATIENTS OR PARTICIPANTS

17 OSA patients and 15 age- and education-matched healthy controls.

INTERVENTIONS

PAP treatment for 3 months.

MEASUREMENTS AND RESULTS

Compared to controls, never-treated OSA patients showed increased activations in the left frontal cortex, medial precuneus, and hippocampus, and decreased activations in the caudal pons. OSA patients showed decreases in activation with treatment in the left inferior frontal gyrus and anterior cingulate cortex, and bilaterally in the hippocampus. Most neurocognitive domains, impaired at baseline, showed significant improvement after treatment.

CONCLUSIONS

OSA patients showed an overrecruitment of brain regions compared to controls, in the presence of the same level of performance on a working-memory task. Decreases of activation in prefrontal and hippocampal structures were observed after treatment in comparison to baseline. These findings may reflect a neural compensation mechanism in never-treated patients, which is reduced by effective treatment.

Follow-up of coiled cerebral aneurysms at 3T: comparison of 3D time-of-flight MR angiography and contrast-enhanced MR angiography

BACKGROUND AND PURPOSE

Our aim was to compare contrast-enhanced MR angiography (CE-MRA) and 3D time-of-flight (TOF) MRA at 3T for follow-up of coiled cerebral aneurysms.

MATERIALS AND METHODS

Fifty-two patients treated with Guglielmi detachable coils for 54 cerebral aneurysms were evaluated at 3T MRA. 3D TOF MRA (TR/TE = 23/3.5; SENSE factor = 2.5) and CE-MRA by using a 3D ultrafast gradient-echo sequence (TR/TE = 5.9/1.8; SENSE factor = 3) enhanced with 0.1-mmol/kg gadobenate dimeglumine were performed in the same session. Source images, 3D maximum intensity projection, 3D shaded surface display, and/or 3D volume-rendered reconstructions were evaluated in terms of aneurysm occlusion/patency and artifact presence.

RESULTS

In terms of clinical classification, the 2 MRA sequences were equivalent for 53 of the 54 treated aneurysms: 21 were considered fully occluded, whereas 16 were considered to have a residual neck and 16 were considered residually patent at follow-up MRA. The remaining aneurysm appeared fully occluded at TOF MRA but had a residual patent neck at CE-MRA. Visualization of residual aneurysm patency was significantly (P = .001) better with CE-MRA compared with TOF MRA for 10 (31.3%) of the 32 treated aneurysms considered residually patent with both sequences. Coil artifacts were present in 5 cases at TOF MRA but in none at CE-MRA. No relationship was apparent between the visualization of patency and either the size of the aneurysm or the interval between embolization and follow-up.

CONCLUSION

At follow-up MRA at 3T, unenhanced TOF and CE-MRA sequences are similarly effective at classifying coiled aneurysms as occluded or residually patent. However, CE-MRA is superior to TOF MRA for visualization of residual patency and is associated with fewer artifacts.

MR angiography of the carotid arteries and intracranial circulation: advantage of a high relaxivity contrast agent

Several studies have shown the usefulness of contrast-enhanced MR angiography (CE-MRA) for imaging the supraortic vessels, and, as a consequence, it has rapidly become a routine imaging modality. The main advantage over unenhanced techniques is the possibility to acquire larger volumes, allowing demonstration of the carotid artery from its origin to the intracranial portion. Most published studies on CE-MRA of the carotid arteries have been performed with standard Gd-based chelates whose T1 relaxivity values are similar. Recently new gadolinium chelates such as gadobenate dimeglumine (Gd-BOP-TA, MultiHance; Bracco Imaging, Milan, Italy) have been developed which have markedly higher intravascular T1 relaxivity values. When administered at an equivalent dose to that of a standard agent, these newer contrast agents produce significantly greater intravascular signal enhancement. The availability of an appropriate high-relaxivity contrast agent might also help to overcome some of the intrinsic technical problems (e. g. those related to flow) that affect time-of-flight (TOF) and phase contrast (PC) MR angiography of the intracranial vasculature. To avoid the problem of superimposition of veins, ultrafast gradient echo MRA techniques with very short TR and TE have been developed. Although the precise sequence parameters vary between manufacturers, they are basically similar. The choice between performing a time-resolved or high spatial resolution CE-MRA examination depends upon the precise clinical application. The most common applications include the study of cerebral aneurysms, arteriovenous malformations, dural arteriovenous fistulas and dural venous diseases.

Acute superior vena cava and right atrial tamponade in an infant after open heart surgery

Early postoperative localized cardiac tamponade occurred in a 4-month old infant after ventricular septal defect repair. The clinical findings were as for acute superior vena cava syndrome. The diagnosis was accurately made using echocardiography and measurement of the superior vena cava and right atrial pressure. Surgical revision was necessary to remove a large clot from the superior vena cava-right atrium junction.

Unusual localisation of a ventricular septal defect following blunt chest trauma

A 64 year old man presented with a traumatic ventricular septal defect following blunt chest trauma 40 years before. Echocardiography and left ventriculography were helpful in locating the unusual septal defect, which was subpulmonary. The shunt was small, but the anomalous chronic overload led to right ventricular failure. The surgical correction was thus too late to improve right ventricular function.

Unusual localisation of a ventricular septal defect following blunt chest trauma

A 64 year old man presented with a traumatic ventricular septal defect following blunt chest trauma 40 years before. Echocardiography and left ventriculography were helpful in locating the unusual septal defect, which was subpulmonary. The shunt was small, but the anomalous chronic overload led to right ventricular failure. The surgical correction was thus too late to improve right ventricular function.

Hypercoagulable state in hypercholesterolemic subjects assessed by platelet-dependent thrombin generation: in vitro effect of cerivastatin

BACKGROUND

Hypercholesterolemia is an important risk factor to develop acute thrombotic complications of atherosclerosis like to myocardial infarction and ischemic stroke. Platelets and coagulation factors are strictly involved in the genesis of such thrombotic events and their hyperactivity in hypercholesterolemic patients has been previously reported. Moreover some cholesterol-lowering molecules (statins) seem to be able of reducing platelet activity.

METHODS

We performed platelet-dependent thrombin generation (colorimetric method) to assess the coagulative potential of 40 caucasian hypercholesterolemic subjects with respect to normal controls and to the grade of hypercholesterolemia. Moreover we observed the effect of platelets from hypercholesterolemics on thrombin generation in plasma from normal subjects. The effect of Cerivastatin on thrombin generation was evaluated too.

RESULTS

Our data show an increased thrombin generation both in mild and high hypercholesterolemic subjects with respect to controls (424.6+/-30.5 vs. 197.1+/-27.4 mIU/ml). No significant difference in the amount of thrombin generation was found between mild and high hypercholesterolemics (399.6+/-20.7 vs. 440.2+/-21.4 mIU/ml). Platelets directly influence thrombin generation and they present an intrinsic hyperactivity that can be modulated by Cerivastatin (223.6+/-24.8 vs. 424.6+/-30.5 mIU/ml).

CONCLUSIONS

Mild hypercholesterolemia is associated with an increased thrombinic potential that may be considered an added risk factor to develop thrombotic events. Platelets directly influences this hypercoagulative state and Cerivastatin is able to reduce thrombin generation by way of a direct interaction with platelets.

[Monotherapy, empirical and targetted, with imipenem-cilastatin in sepsis of bacterial origin]

The authors describe an open study in 22 patients with febrile conditions of unknown origin who were treated with imipenem-cilastatin while waiting for routine laboratory and culture tests. These were done immediately at the patients' entry into hospital, after which imipenem-cilastatin treatment was started immediately, and was subsequently confirmed by the isolates and culture tests. The drug was found to be active and to eradicate the responsible organism in all cases. In addition, it was found to be easy to handle and not to give rise to side-effects or changes in laboratory tests.