Magnetic resonance imaging short protocols for intraductal papillary mucinous neoplasm (IPMN) surveillance: The time has come.

BACKGROUND/OBJECTIVES: To analyze the diagnostic performance of three short magnetic resonance imaging (MRI) protocols for the follow-up of pancratic intraductal papillary mucinous neoplasms (IPMN). METHODS: Follow-up MRI examinations of 287 patients with IPMN performed in two centers were retrospectively retrieved. Four MRI protocols were identified as follows: T1-weighted (T1w), T2-weighted (T2w), and MRCP sequences (protocol 1); T1w, T2w, MRCP, and diffusion-weighted (DWI) sequences (protocol 2); T1w, T2w, MRCP, and post-contrast T1w-sequences (protocol 3); and a comprehensive protocol including all previous sequences (protocol 4). Three radiologists with different experience in abdominal imaging expressed their opinion upon the optimal patient's management upon the evaluation of each protocol. Intra-and inter-observer agreement and concordance with the clinical decision expressed by a pancreatic surgeon were calculated with Cohen's kappa test. RESULTS: 223 patients were included (66±10 years; 92 men, 131 women). 143 patients had branch-duct-IPMNs, 25 main-duct-IPMNs and 55 mixed-type-IPMNs. 79 patients underwent surgery, resulting in 52 high-grade dysplasia (HGD) and 27 low-grade dysplasia (LGD). Concordance for the expert reader between protocols 1, 2 and 3 and the actual clinical decision were 0.63, 0.72, and 0.74 respectively (95% CI, 0.53-0.73, 0.63-0.81, and 0.65-0.83). Inter-observer agreement between reader 1 and reader 2, reader 1 and reader 3, and reader 2 and reader 3 were: 0.71, 0.50, and 0.75 for protocol 1 (95% CI, 0.63-0.81, 0.40-0.60, and 0.66-0.84);0.68, 0.54, and 0.84 for protocol 2 (95% CI, 0.59-0.77, 0.44-0.64, and 0.76-0.91); and 0.77, 0.65, and 0.86 for protocol 3 (95% CI, 0.69-0.86, 0.55-0.74, and 0.80-0.93). CONCLUSIONS: Short MRI protocol is suitable for IPMN surveillance.

Role of corpus callosum in unconscious vision.

The existence of unconscious visually triggered behavior in patients with cortical blindness (e.g., homonymous hemianopia) has been amply demonstrated and the neural bases of this phenomenon have been thoroughly studied. However, a crosstalk between the two hemispheres as a possible mechanism of unconscious or partially conscious vision has not been so far considered. Thus, the aim of this study was to assess the relationship between structural and functional properties of the corpus callosum (CC), as shown by probabilistic tractography (PT), behavioral detection/discrimination performance and level of perceptual awareness in the blind field of patients with hemianopia. Twelve patients were tested in two tasks with black-and-white visual square-wave gratings, one task of movement and the other of orientation. The stimuli were lateralized to one hemifield either intact or blind. A PT analysis was carried out on MRI data to extract fiber properties along the CC (genu, body, and splenium). Compared with a control group of participants without brain damage, patients showed lower FA values in all three CC sections studied. For the intact hemifield we found a significant correlation between PT values and visual detection/discrimination accuracy. For the blind hemifield the level of perceptual awareness correlated with PT values for all three CC sections in the movement task. Importantly, significant differences in all three CC sections were found also between patients with above-vs. chance detection/discrimination performance while differences in the genu were found between patients with and without perceptual awareness. Overall, our study provides evidence that the properties of CC fibers are related to the presence of unconscious stimulus detection/discrimination and to hints of perceptual awareness for stimulus presentation to the blind hemifield. These results underline the importance of information exchange between the damaged and the healthy hemisphere for possible partial or full recovery from hemianopia.

Resting-state functional connectivity in multiple sclerosis patients receiving nabiximols for spasticity.

BACKGROUND: Nabiximols (Sativex®) is a cannabinoid approved for multiple sclerosis (MS)-related spasticity. Its mechanism of action is partially understood, and efficacy is variable. OBJECTIVE: To conduct an exploratory analysis of brain networks connectivity changes on resting state (RS) functional MRI (fMRI) of MS patients treated with nabiximols. METHODS: We identified a group of MS patients treated with Sativex® at Verona University Hospital, who underwent RS brain fMRI in the 4 weeks before (T0) and 4-8 weeks after (T1) treatment start. Sativex® response was defined as ≥ 20% spasticity Numerical Rating Scale score reduction at T1 vs. T0. Connectivity changes on fMRI were compared between T0 and T1 in the whole group and according to response status. ROI-to-ROI and seed-to-voxel connectivity were evaluated. RESULTS: Twelve MS patients (7 males) were eligible for the study. Seven patients (58.3%) resulted Sativex® responders at T1. On fMRI analysis, Sativex® exposure was associated with global brain connectivity increase (particularly in responders), decreased connectivity of motor areas, and bidirectional connectivity changes of the left cerebellum with a number of cortical areas. CONCLUSIONS: Nabiximols administration is associated with brain connectivity increase of MS patients with spasticity. Modulation of sensorimotor cortical areas and cerebellum connectivity could play a role in nabiximols effect.

Path Tracing vs. Volume Rendering Technique in Post-Surgical Assessment of Bone Flap in Oncologic Head and Neck Reconstructive Surgery: A Preliminary Study.

This study aims to compare a relatively novel three-dimensional rendering called Path Tracing (PT) to the Volume Rendering technique (VR) in the post-surgical assessment of head and neck oncologic surgery followed by bone flap reconstruction. This retrospective study included 39 oncologic patients who underwent head and neck surgery with free bone flap reconstructions. All exams were acquired using a 64 Multi-Detector CT (MDCT). PT and VR images were created on a dedicated workstation. Five readers, with different expertise in bone flap reconstructive surgery, independently reviewed the images (two radiologists, one head and neck surgeon and two otorhinolaryngologists, respectively). Every observer evaluated the images according to a 5-point Likert scale. The parameters assessed were image quality, anatomical accuracy, bone flap evaluation, and metal artefact. Mean and median values for all the parameters across the observer were calculated. The scores of both reconstruction methods were compared using a Wilcoxon matched-pairs signed rank test. Inter-reader agreement was calculated using Spearman's rank correlation coefficient. PT was considered significantly superior to VR 3D reconstructions by all readers (p < 0.05). Inter-reader agreement was moderate to strong across four out of five readers. The agreement was stronger with PT images compared to VR images. In conclusion, PT reconstructions are significantly better than VR ones. Although they did not modify patient outcomes, they may improve the post-surgical evaluation of bone-free flap reconstructions following major head and neck surgery.

Radiofrequency ablation of hepatocellular carcinoma: CT texture analysis of the ablated area to predict local recurrence.

PURPOSE: To investigate the role of CT-texture analysis of liver ablation area to predict local recurrence after HCC ablation. METHODS: Patients treated with liver ablation were retrospectively enrolled. CT-texture analysis was performed on the core and borders of ablation area 1-2 months after procedure. Tumors were grouped according to the onset of local recurrence at follow-up (persistence, recurrence-free, short- or long-term recurrence). Differences in texture parameters and which parameters were predictive of recurrence risk were assessed using a Cox regression model. RESULTS: 151 HCCs were treated in 98 patients (72 ± 9 years, 83 men). 68 HCCs reported no disease recurrence, 32 persistent disease, 19 short-term and 32 long-term recurrence. Median follow-up was 280 [IQR: 156-569] days. Venous phase (Ven)Skewness (HR 6.07, 1.29-28.6, p =.02) and VenKurtosis (HR 2.27, 1.23-4.21, p =.01) of the ablation core were predictive of short-term recurrence. VenHUmean (HR 0.30, 0.11-0.81, p =.02) and VenGLRLM_HGRE (HR 1.06, 1.01-1.11, p =.02) of the core were independent predictors of tumor recurrence (C-index 0.64, CI 0.52-0.76, p =.03). Arterial phase (Art)Entropy of ablation border predicted the recurrence risk (HR 3.15, 1.05-9.42, p =.04) and values higher than 3.71 reported an increased recurrence incidence (p =.05). ArtHUstd (HR 1.14, 1.04-1.24, p =.01), LateHUmean (HR 8.69, 1.11-68.23, p =.04), LateGLRLM_HGRE (HR 0.9, 0.82-0.99, p =.03), LateGLZLM_HGZE (HR 1.01, 1.00-1.02, p <.01) and LateGLZLM_SZHGE (HR 0.99, 0.99-1.00, p =.02) of ablation border were independent predictors of local recurrence risk (C-index 0.73, CI 0.61-0.86, p <.01). CONCLUSIONS: CT texture analysis of ablation area performed at 1-2 months follow-up could estimate the risk of local recurrence of hepatocellular carcinoma treated by radiofrequency ablation.

Persistent chemosensory dysfunction in a young patient with mild COVID-19 with partial recovery 15 months after the onset.

OBJECTIVE: It is reported that recovery from COVID-19 chemosensory deficit generally occurs in a few weeks, although olfactory dysfunction may persist longer. Here, we provide a detailed follow-up clinical investigation in a very young female patient (17-year-old) with a long-lasting anosmia after a mild infection, with partial recovery 15 months after the onset. METHODS: Neuroimaging and neurophysiologic assessments as well as olfactory mucosa swabbing for microbiological and immunocytochemical analyses were performed. Olfactory and gustatory evaluations were conducted through validated tests. RESULTS: Chemosensory evaluations were consistent with anosmia associated with parosmia phenomena and gustatory impairment, the latter less persistent. Brain MRI (3.0 T) showed no microvascular injury in olfactory bulbs and brain albeit we cannot rule out slight structural abnormalities during the acute phase, and a high-density EEG was negative. Immunocytochemistry of olfactory mucosa swabs showed high expression of ACE2 in sustentacular cells and lower dot-like cytoplasmic positivity in neuronal-shaped cells. DISCUSSION: The occurrence of long-term persistent olfactory deficit in spite of the absence of structural brain and olfactory bulb involvement supports the view of a possible persistent dysfunction of both sustentacular cells and olfactory neurons. The gustatory dysfunction even if less persisting for the described features could be related to a primary gustatory system involvement. Future longitudinal studies are needed to investigate the persistence of chemosensory impairment, which could have a relevant impact on the daily life.

CT radiomic models to distinguish COVID-19 pneumonia from other interstitial pneumonias.

PURPOSE: To classify COVID-19, COVID-19-like and non-COVID-19 interstitial pneumonia using lung CT radiomic features. MATERIAL AND METHODS: CT data of 115 patients with respiratory symptoms suspected for COVID-19 disease were retrospectively analyzed. Based on the results of nasopharyngeal swab, patients were divided into two main groups, COVID-19 positive (C +) and COVID-19 negative (C-), respectively. C- patients, however, presented with interstitial lung involvement. A subgroup of C-, COVID-19-like (CL), were considered as highly suggestive of COVID pneumonia at CT. Radiomic features were extracted from the whole lungs. A dual machine learning (ML) model approach was used. The first one excluded CL patients from the training set, eventually included on the test set. The second model included the CL patients also in the training set. RESULTS: The first model classified C + and C- pneumonias with AUC of 0.83. CL median response (0.80) was more similar to C + (0.92) compared to C- (0.17). Radiomic footprints of CL were similar to the C + ones (possibly false negative swab test). The second model, however, merging C + with CL patients in the training set, showed a slight decrease in classification performance (AUC = 0.81). CONCLUSION: Whole lung ML models based on radiomics can classify C + and C- interstitial pneumonia. This may help in the correct management of patients with clinical and radiological stigmata of COVID-19, however presenting with a negative swab test. CL pneumonia was similar to C + pneumonia, albeit with slightly different radiomic footprints.

An Overview of Artificial Intelligence Applications in Liver and Pancreatic Imaging.

Artificial intelligence (AI) is one of the most promising fields of research in medical imaging so far. By means of specific algorithms, it can be used to help radiologists in their routine workflow. There are several papers that describe AI approaches to solve different problems in liver and pancreatic imaging. These problems may be summarized in four different categories: segmentation, quantification, characterization and image quality improvement. Segmentation is usually the first step of successive elaborations. If done manually, it is a time-consuming process. Therefore, the semi-automatic and automatic creation of a liver or a pancreatic mask may save time for other evaluations, such as quantification of various parameters, from organs volume to their textural features. The alterations of normal liver and pancreas structure may give a clue to the presence of a diffuse or focal pathology. AI can be trained to recognize these alterations and propose a diagnosis, which may then be confirmed or not by radiologists. Finally, AI may be applied in medical image reconstruction in order to increase image quality, decrease dose administration (referring to computed tomography) and reduce scan times. In this article, we report the state of the art of AI applications in these four main categories.

CT Simplified Radiomic Approach to Assess the Metastatic Ductal Adenocarcinoma of the Pancreas.

The aim of this study was to perform a simplified radiomic analysis of pancreatic ductal adenocarcinoma based on qualitative and quantitative tumor features and to compare the results between metastatic and non-metastatic patients. A search of our radiological, surgical, and pathological databases identified 1218 patients with a newly diagnosed pancreatic ductal adenocarcinoma who were referred to our Institution between January 2014 and December 2018. Computed Tomography (CT) examinations were reviewed analyzing qualitative and quantitative features. Two hundred eighty-eight patients fulfilled the inclusion criteria and were included in this study. Overall, metastases were present at diagnosis in 86/288 patients, while no metastases were identified in 202/288 patients. Ill-defined margins and a hypodense appearance on portal-phase images were significantly more common among patients with metastases compared to non-metastatic patients (p < 0.05). Metastatic tumors showed a significantly larger size and significantly lower arterial index, perfusion index, and permeability index compared to non-metastatic tumors (p < 0.05). In the management of pancreatic ductal adenocarcinoma, early detection and correct staging are key elements. The study of computerized tomography characteristics of pancreatic ductal adenocarcinoma showed substantial differences, both qualitative and quantitative, between metastatic and non-metastatic disease.

MRI-guided breast biopsy based on diffusion-weighted imaging: a feasibility study.

OBJECTIVES: This study evaluated the feasibility of DWI for lesion targeting in MRI-guided breast biopsies. Furthermore, it assessed device positioning on DWI during biopsy procedures. METHODS: A total of 87 biopsy procedures (5/87 bilateral) consecutively performed between March 2019 and June 2020 were retrospectively reviewed: in these procedures, a preliminary DWI sequence (b = 1300 s/mm2) was acquired to assess lesion detectability. We included 64/87 procedures on lesions detectable at DWI; DWI sequences were added to the standard protocol to localize lesion and biopsy device and to assess the site marker correct positioning. RESULTS: Mass lesions ranged from 5 to 48 mm, with a mean size of 10.7 mm and a median size of 8 mm. Non-mass lesions ranged from 7 to 90 mm, with a mean size of 33.9 mm and a median size of 31 mm. Positioning of the coaxial system was confirmed on both T1-weighted and DWI sequences. At DWI, the biopsy needle was detectable in 62/64 (96.9%) cases; it was not visible in 2/64 (3.1%) cases. The site marker was always identified using T1-weighted imaging; a final DWI sequence was acquired in 44/64 cases (68.8%). In 42/44 cases (95.5%), the marker was recognizable at DWI. CONCLUSIONS: DWI can be used as a cost-effective, highly reliable technique for targeting both mass and non-mass lesions, with a minimum size of 5 mm, detectable at pre-procedural DWI. DWI is also a feasible technique to localize the biopsy device and to confirm the deployment of the site marker. KEY POINTS: • MRI-guided breast biopsy is performed in referral centers by an expert dedicated staff, based on prior MR imaging; contrast agent administration is usually needed for lesion targeting. • DWI represents a feasible, highly reliable technique for lesion targeting, avoiding contrast agent administration. • DWI allows a precise localization of both biopsy needle device and site marker.

Magnetic resonance (MR) for mural nodule detection studying Intraductal papillary mucinous neoplasms (IPMN) of pancreas: Imaging-pathologic correlation.

PURPOSE: Magnetic Resonance (MR) is recommended to diagnose Intraductal Papillary Mucinous Neoplasms (IPMN) and in the follow-up of borderline lesions. The purpose of this work is to evaluate the diagnostic accuracy of dynamic MR with Diffusion Weighted Imaging (DWI) in the identification of mural nodules of pancreatic IPMN by using pathological analysis as gold standard. MATERIALS AND METHODS: Ninety-one preoperative MR with histopathological diagnosis of IPMN were reviewed by two radiologists. Presence, number and size of mural nodule, signal intensity of the nodule on T1-weighted imaging (T1-WI) after contrast medium administration and on DWI. Inter-observer agreement was evaluated. RESULTS: Significant correlation (p < 0.0001) were found for presence of nodules > 5 mm on MR and pathological specimen, size and number of mural nodules evaluated on pathological review and degree of dysplasia, size and number of mural nodules evaluated on MR and tumoral dysplasia, presence of nodule > 5 mm with enhancement after contrast medium administration and hyperintensity on DWI and degree of dysplasia. Interobserver agreement was moderate for the presence of mural nodule (K = 0.56), for the presence of high signal intensity on DWI (K = 0.57) and enhancement of mural nodule (K = 0.58). Apparent Diffusion Coefficient (ADC) map histogram analysis showed a correlation between Entropy of the entire cystic lesion and the degree of dysplasia (p < 0.034). CONCLUSIONS: MR with dynamic and DWI sequences was an accurate method for the identification of ≥ 5 mm solid nodules of the IPMNs and correlate with the lesion malignancy. Entropy, calculated from the histogram analysis of the IPMN ADC map, correlated with the lesion dysplasia.

Visuo-spatial attention to the blind hemifield of hemianopic patients: Can it survive the impairment of visual awareness?

The general aim of this study was to assess the effect produced by visuo-spatial attention on both behavioural performance and brain activation in hemianopic patients following visual stimulus presentation to the blind hemifield. To do that, we tested five hemianopic patients and six age-matched healthy controls in an MRI scanner during the execution of a Posner-like paradigm using a predictive central cue. Participants were instructed to covertly orient attention toward the blind or sighted hemifield in different blocks while discriminating the orientation of a visual grating. In patients, we found significantly faster reaction times (RT) in valid and neutral than invalid trials not only in the sighted but also in the blind hemifield, despite the impairment of consciousness and performance at chance. As to the fMRI signal, in valid trials we observed the activation of ipsilesional visual areas (mainly lingual gyrus - area 19) during the orientation of attention toward the blind hemifield. Importantly, this activation was similar in patients and controls. In order to assess the related functional network, we performed a psychophysiological interactions (PPI) analysis that revealed an increased functional connectivity (FC) in patients with respect to controls between the ipsilesional lingual gyrus and ipsilateral fronto-parietal as well as contralesional parietal regions. Moreover, the shift of attention from the blind to the sighted hemifield revealed stronger FC between the contralesional visual areas V3/V4 and ipsilateral parietal regions in patients than controls. These results indicate a higher cognitive effort in patients when paying attention to the blind hemifiled or when shifting attention from the blind to the sighted hemfield, possibly as an attempt to compensate for the visual loss. Taken together, these results show that hemianopic patients can covertly orient attention toward the blind hemifield with a top-down mechanism by activating a functional network mainly including fronto-parietal regions belonging to the dorsal attentional network.

What cortical areas are responsible for blindsight in hemianopic patients?

The presence of above-chance unconscious behavioral responses following stimulus presentation to the blind hemifield of hemianopic patients (blindsight) is a well-known phenomenon. What is still lacking is a systematic study of the neuroanatomical bases of two distinct aspects of blindsight: the unconscious above chance performance and the phenomenological aspects that may be associated. Here, we tested 17 hemianopic patients in two tasks i.e. movement and orientation discrimination of a visual grating presented to the sighted or blind hemifield. We classified patients in four groups on the basis of the presence of above chance unconscious discrimination without or with perceptual awareness reports for stimulus presentation to the blind hemifield. A fifth group was represented by patients with interruption of the Optic Radiation. In the various groups we carried out analyses of lesion extent of various cortical areas, probabilistic tractography as well as assessment of the cortical thickness of the intact hemisphere. All patients had lesions mainly, but not only, in the occipital lobe and the statistical comparison of their extent provided clues as to the critical anatomical substrate of unconscious above-chance performance and of perceptual awareness reports, respectively. In fact, the two areas that turned out to be critical for above-chance performance in the discrimination of moving versus non-moving visual stimuli were the Precuneus and the Posterior Cingulate Gyrus while for perceptual awareness reports the crucial areas were Intracalcarine, Supracalcarine, Cuneus, and the Posterior Cingulate Gyrus. Interestingly, the proportion of perceptual awareness reports was higher in patients with a spared right hemisphere. As to probabilistic tractography, all pathways examined yielded higher positive values for patients with perceptual awareness reports. Finally, the cortical thickness of the intact hemisphere was greater in patients showing above-chance performance than in those at chance. This effect is likely to be a result of neuroplastic compensatory mechanisms.

Neural bases of unconscious orienting of attention in hemianopic patients: Hemispheric differences.

The aim of this research was to study the behavioral and neurophysiological correlates of visual attention orientation to unseen stimuli presented to the blind hemifield of hemianopic patients, and the existence of hemispheric differences for this kind of unconscious attention. Behaviorally, by using a Posner paradigm, we found a significant attention effect in speed of response to unseen stimuli similar to that observed in the sighted hemifield and in healthy participants for visible stimuli. Moreover, event-related potential (ERP) and oscillatory attention-related activity were present following stimulus presentation to the blind hemifield. Importantly, in patients this pattern of activity was different as a function of the side of the brain lesion: Left damaged patients showed attention-related ERP and oscillatory activity broadly similar to that found in healthy participants. In contrast, right damaged patients showed a radically different pattern. These data confirm and extend to neurophysiological mechanisms the existence of unconscious visual orienting and are in keeping with a right hemisphere dominance for both unconscious and conscious attention.

Correlation of MR features and histogram-derived parameters with aggressiveness and outcomes after resection in pancreatic ductal adenocarcinoma.

PURPOSE: To evaluate MR-derived histogram parameters in predicting aggressiveness and surgical outcomes in patients with PDAC, by correlating them to pathological features, recurrence-free survival (RFS), and overall survival (OS). METHODS: Pre-operative MR examinations of 103 patients with PDAC between July 2014 and September 2018 were retrospectively analyzed. Morphologic features and whole-tumor histogram-derived parameters were correlated to pathological features using Fisher's exact or Mann-Whitney U tests and receiver operating characteristic (ROC) curves were constructed for significant parameters. Cox regression analysis and Kaplan-Meier curves were used to determine the association of clinical-pathological variables, morphological features, and histogram-derived parameters with RFS and OS. RESULTS: T1entropy, ADCentropy, T2kurtosis, and ADCuniformity had the highest area under the curve (AUC) for prediction of vascular infiltration, nodal metastases, microscopic vascular invasion, and peripancreatic fat invasion (.657, .742, .760, and .818, respectively). Poor tumor differentiation (P = 0.002, hazard ratio-HR = 4.08), nodal ratio (P = 0.034, HR 6.95), and ADCmaximum (P = 0.021, HR 1.01) were significant predictors of RFS. Poor tumor differentiation (P = 0.05, HR 2.82), ADCuniformity (P = 0.02, HR 3.32), and arterialentropy (P = 0.02, HR 6.84) were the only significant predictors of death; patients with higher arterialentropy had significantly shorter OS than patients who did not meet this criterion (P = 0.02; median OS 24 vs 31 months). CONCLUSION: Histogram-derived parameters may predict adverse pathological features in PDACs. High arterialentropy seems to be associated with short OS after surgery in patients with PDAC.

Neural bases of visual processing of moving and stationary stimuli presented to the blind hemifield of hemianopic patients.

Unilateral damage to post-chiasmatic visual pathways or cortical areas results in the loss of vision in the contralateral hemifield, known as hemianopia. Some patients, however, may retain the ability to perform an above chance unconscious detection or discrimination of visual stimuli presented to the blind hemifield, known as "blindsight". An important finding in blindsight research is that it can often be elicited by moving stimuli. Therefore, in the present study, we wanted to test whether moving stimuli might yield blindsight phenomena in patients with cortical lesions resulting in hemianopia, in a discrimination task where stimulus movement is orthogonal to the feature of interest. This could represent an important strategy for rehabilitation because it might improve discrimination ability of stimulus features different but related to movement, e.g. line orientation. We tested eight hemianopic patients and eight age-matched healthy controls in an orientation discrimination task with moving or static visual stimuli. During performance of the task we carried out fMRI scanning and tractography. Behaviourally, we did not find a reliable main effect of motion on orientation discrimination; however, an important result was that in different patients blindsight could occur only with moving or stationary stimuli or with both. As to brain imaging results, following presentation of moving stimuli to the blind hemifield, a widespread fronto-parietal bilateral network was recruited including areas of the dorsal stream and in particular bilateral motion area hMT + whose activation positively correlated with behavioural performance. This bilateral network was not activated in controls suggesting that it represents a compensatory functional change following brain damage. Moreover, there was a higher activation of ipsilesional area hMT+ in patients who performed above chance in the moving condition. By contrast, in patients who performed above chance in the static condition, we found a higher activation of contralesional area V1 and extrastriate visual areas. Finally, we found a linear relationship between structural integrity of the ipsilesional pathway connecting lateral geniculate nucleus (LGN) with motion area hMT+ and both behavioural performance and ipsilesional hMT + activation. These results support the role of LGN in modulating performance as well as BOLD amplitude in the absence of visual awareness in ipsilesional area hMT+ during an orientation discrimination task with moving stimuli.

Functional interactions in patients with hemianopia: A graph theory-based connectivity study of resting fMRI signal.

The assessment of task-independent functional connectivity (FC) after a lesion causing hemianopia remains an uncovered topic and represents a crucial point to better understand the neural basis of blindsight (i.e. unconscious visually triggered behavior) and visual awareness. In this light, we evaluated functional connectivity (FC) in 10 hemianopic patients and 10 healthy controls in a resting state paradigm. The main aim of this study is twofold: first of all we focused on the description and assessment of density and intensity of functional connectivity and network topology with and without a lesion affecting the visual pathway, and then we extracted and statistically compared network metrics, focusing on functional segregation, integration and specialization. Moreover, a study of 3-cycle triangles with prominent connectivity was conducted to analyze functional segregation calculated as the area of each triangle created connecting three neighboring nodes. To achieve these purposes we applied a graph theory-based approach, starting from Pearson correlation coefficients extracted from pairs of regions of interest. In these analyses we focused on the FC extracted by the whole brain as well as by four resting state networks: The Visual (VN), Salience (SN), Attention (AN) and Default Mode Network (DMN), to assess brain functional reorganization following the injury. The results showed a general decrease in density and intensity of functional connections, that leads to a less compact structure characterized by decrease in functional integration, segregation and in the number of interconnected hubs in both the Visual Network and the whole brain, despite an increase in long-range inter-modules connections (occipito-frontal connections). Indeed, the VN was the most affected network, characterized by a decrease in intra- and inter-network connections and by a less compact topology, with less interconnected nodes. Surprisingly, we observed a higher functional integration in the DMN and in the AN regardless of the lesion extent, that may indicate a functional reorganization of the brain following the injury, trying to compensate for the general reduced connectivity. Finally we observed an increase in functional specialization (lower between-network connectivity) and in inter-networks functional segregation, which is reflected in a less compact network topology, highly organized in functional clusters. These descriptive findings provide new insight on the spontaneous brain activity in hemianopic patients by showing an alteration in the intrinsic architecture of a large-scale brain system that goes beyond the impairment of a single RSN.

Residual pancreatic function after pancreaticoduodenectomy is better preserved with pancreaticojejunostomy than pancreaticogastrostomy: A long-term analysis.

BACKGROUND: Pancreatico-enteric anastomosis after pancreaticoduodenectomy can be performed using either a pancreaticojejunostomy (PJ) or pancreaticogastrostomy (PG). Differences in surgical outcomes are still a matter of debate, and less is known about long-term functional outcomes. METHODS: Twelve years after the conclusion of a comparative study evaluating the surgical outcomes of PJ and PG (Bassi et al., Ann Surg 2005), available patients underwent morphological and functional pancreatic assessment: pancreatic volume and duct diameter measured by MRI, impaired secretion after secretin, fecal fat, fecal elastase-1 (FE-1), serum vitamin D and endocrine function. Quality of life and symptom scores were evaluated with the EORTC QLQ-C30 questionnaire. RESULTS: Only 34 patients were available for assessment. No differences were found in terms of BMI variation, endocrine function, quality of life or symptoms. Exocrine function was more severely impaired after PG than after PJ (fecal fats 26.6 ±â€¯4.1 vs 18.2 ±â€¯3.6 g/day; FE-1 121.4 ±â€¯6.7 vs 170.2 ±â€¯25.5 µg/g, vitamin D 18.1 ±â€¯1.8 vs. 23.2 ±â€¯3.1 ng/mL). MRI assessment identified a lower pancreatic volume (26 ±â€¯3.1 vs. 36 ±â€¯4.1 cm3) and a more dilated pancreatic duct (4.6 ±â€¯0.92 vs. 2.4 ±â€¯0.18 mm) in patients with PG compared to those with PJ. CONCLUSION: Compared to PJ, PG is associated with a more severely impaired exocrine function long-term, but they result similar endocrine function and quality of life. In patients with a long life expectancy, this should be taken into account.

Neural Correlates of Visuospatial Attention to Unseen Stimuli in Hemianopic Patients. A Steady-State Visual Evoked Potential Study.

The relationship between attention and awareness is a topic of great interest in cognitive neuroscience. Some studies in healthy participants and hemianopic patients have shown dissociation between these two processes. In contrast, others confirmed the classic notion that the two processes are mutually exclusive. To try and cast further light on this fascinating dilemma, in the present study we have investigated the neural mechanisms of visual spatial attention when perceptual awareness is totally lacking. To do that, we monitored with steady-state visual evoked potentials (SSVEPs) the neurophysiological correlates of endogenous spatial attention to unseen stimuli presented to the blind field of hemianopic patients. Behaviourally, stimulus detection (a brief change in the orientation of a gabor grating) was absent in the blind hemifield while in the sighted field there was a lower, but non-significant, performance in hit rate with respect to a healthy control group. Importantly, however, in both blind and sighted hemifield of hemianopics (as well as in healthy participants) SSVEP recordings showed an attentional effect with higher frequency power in the attended than unattended condition. The scalp distribution of this effect was broadly in keeping with the location of the dorsal system of endogenous spatial attention. In conclusion, the present results provide evidence that the neural correlates of spatial attention are present regardless of visual awareness and this is in accord with the general hypothesis of a possible dissociation between attention and awareness.

CT Enhancement and 3D Texture Analysis of Pancreatic Neuroendocrine Neoplasms.

To evaluate pancreatic neuroendocrine neoplasms (panNENs) grade prediction by means of qualitative and quantitative CT evaluation, and 3D CT-texture analysis. Patients with histopathologically-proven panNEN, availability of Ki67% values and pre-treatment CT were included. CT images were retrospectively reviewed, and qualitative and quantitative images analysis were done; for quantitative analysis four enhancement-ratios and three permeability-ratios were created. 3D CT-texture imaging analysis was done (Mean Value; Variance; Skewness; Kurtosis; Entropy). Subsequently, these features were compared among the three grading (G) groups. 304 patients affected by panNENs were considered, and 100 patients were included. At qualitative evaluation, frequency of irregular margins was significantly different between tumor G groups. At quantitative evaluation, for all ratios, comparisons resulted statistical significant different between G1 and G3 groups and between G2 and G3 groups. At 3D CT-texture analysis, Kurtosis resulted statistical significant different among three G groups and Entropy resulted statistical significant different between G1 and G3 and between G2 and G3 groups. Quantitative CT evaluation of panNENs can predict tumor grade, discerning G1 from G3 and G2 from G3 tumors. CT-texture analysis can predict panNENs tumor grade, distinguishing G1 from G3 and G2 from G3, and G1 from G2 tumors.