Diagnostic value of 18F-FDG PET/CT versus diffusion-weighted MRI in detection of residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal squamous cell carcinoma: A prospective study.

BACKGROUND: Despite advances in treatment, residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal squamous cell carcinoma (SCC) remain a challenge in clinical management and require accurate and timely detection for optimal salvage therapy. This study aimed to compare the diagnostic value of Fluorine 18 (18F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) in detecting residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal SCC. METHODS: A prospective study was conducted on 30 patients who presented with new symptoms after definitive (chemo) radiotherapy for laryngeal (n = 21) and hypopharyngeal (n = 9) carcinoma. Both 18F-FDG PET/CT and DW-MRI were performed and histopathologic analysis served as the standard of reference. RESULTS: Histopathology showed 20 patients as positive and 10 as negative for tumors. 18F-FDG PET/CT detected all tumors correctly but was falsely positive in one case. DW-MRI detected tumors in 18 out of 20 positive patients and correctly excluded tumors in all negative patients. The sensitivity and specificity of 18F-FDG PET/CT were 100% and 90%, respectively, while the values for DW-MRI were 90% and 100%, respectively. CONCLUSIONS: The study concludes that 18F-FDG PET/CT is slightly superior to DW-MRI in detecting residual or recurrent tumors after definitive (chemo) radiotherapy for laryngeal and hypopharyngeal SCC. The combined use of 18F-FDG PET/CT and DW-MRI can potentially improve specificity in therapy response evaluation.

Arterial Spin Labeling (ASL) in Neuroradiological Diagnostics - Methodological Overview and Use Cases.

BACKGROUND: Arterial spin labeling (ASL) is a magnetic resonance imaging (MRI)-based technique using labeled blood-water of the brain-feeding arteries as an endogenous tracer to derive information about brain perfusion. It enables the assessment of cerebral blood flow (CBF). METHOD: This review aims to provide a methodological and technical overview of ASL techniques, and to give examples of clinical use cases for various diseases affecting the central nervous system (CNS). There is a special focus on recent developments including super-selective ASL (ssASL) and time-resolved ASL-based magnetic resonance angiography (MRA) and on diseases commonly not leading to characteristic alterations on conventional structural MRI (e. g., concussion or migraine). RESULTS: ASL-derived CBF may represent a clinically relevant parameter in various pathologies such as cerebrovascular diseases, neoplasms, or neurodegenerative diseases. Furthermore, ASL has also been used to investigate CBF in mild traumatic brain injury or migraine, potentially leading to the establishment of imaging-based biomarkers. Recent advances made possible the acquisition of ssASL by selective labeling of single brain-feeding arteries, enabling spatial perfusion territory mapping dependent on blood flow of a specific preselected artery. Furthermore, ASL-based MRA has been introduced, providing time-resolved delineation of single intracranial vessels. CONCLUSION: Perfusion imaging by ASL has shown promise in various diseases of the CNS. Given that ASL does not require intravenous administration of a gadolinium-based contrast agent, it may be of particular interest for investigations in pediatric cohorts, patients with impaired kidney function, patients with relevant allergies, or patients that undergo serial MRI for clinical indications such as disease monitoring. KEY POINTS: · ASL is an MRI technique that uses labeled blood-water as an endogenous tracer for brain perfusion imaging.. · It allows the assessment of CBF without the need for administration of a gadolinium-based contrast agent.. · CBF quantification by ASL has been used in several pathologies including brain tumors or neurodegenerative diseases.. · Vessel-selective ASL methods can provide brain perfusion territory mapping in cerebrovascular diseases.. · ASL may be of particular interest in patient cohorts with caveats concerning gadolinium administration..

Modern preoperative imaging and functional mapping in patients with intracranial glioma.

Magnetic resonance imaging (MRI) in therapy-naïve intracranial glioma is paramount for neuro-oncological diagnostics, and it provides images that are helpful for surgery planning and intraoperative guidance during tumor resection, including assessment of the involvement of functionally eloquent brain structures. This study reviews emerging MRI techniques to depict structural information, diffusion characteristics, perfusion alterations, and metabolism changes for advanced neuro-oncological imaging. In addition, it reflects current methods to map brain function close to a tumor, including functional MRI and navigated transcranial magnetic stimulation with derived function-based tractography of subcortical white matter pathways. We conclude that modern preoperative MRI in neuro-oncology offers a multitude of possibilities tailored to clinical needs, and advancements in scanner technology (e. g., parallel imaging for acceleration of acquisitions) make multi-sequence protocols increasingly feasible. Specifically, advanced MRI using a multi-sequence protocol enables noninvasive, image-based tumor grading and phenotyping in patients with glioma. Furthermore, the add-on use of preoperatively acquired MRI data in combination with functional mapping and tractography facilitates risk stratification and helps to avoid perioperative functional decline by providing individual information about the spatial location of functionally eloquent tissue in relation to the tumor mass. KEY POINTS:: · Advanced preoperative MRI allows for image-based tumor grading and phenotyping in glioma.. · Multi-sequence MRI protocols nowadays make it possible to assess various tumor characteristics (incl. perfusion, diffusion, and metabolism).. · Presurgical MRI in glioma is increasingly combined with functional mapping to identify and enclose individual functional areas.. · Advancements in scanner technology (e. g., parallel imaging) facilitate increasing application of dedicated multi-sequence imaging protocols.. CITATION FORMAT: · Sollmann N, Zhang H, Kloth C et al. Modern preoperative imaging and functional mapping in patients with intracranial glioma. Fortschr Röntgenstr 2023; 195: 989 - 1000.

Pictorial Review on Imaging Findings in Cerebral CTP in Patients with Acute Stroke and Its Mimics: A Primer for General Radiologists.

The imaging evaluation of computed tomography (CT), CT angiography (CTA), and CT perfusion (CTP) is of crucial importance in the setting of each emergency department for suspected cerebrovascular impairment. A fast and clear assignment of characteristic imaging findings of acute stroke and its differential diagnoses is essential for every radiologist. Different entities can mimic clinical signs of an acute stroke, thus the knowledge and fast identification of stroke mimics is important. A fast and clear assignment is necessary for a correct diagnosis and a rapid initiation of appropriate therapy. This pictorial review describes the most common imaging findings in CTP with clinical signs for acute stroke or other acute neurological disorders. The knowledge of these pictograms is therefore essential and should also be addressed in training and further education of radiologists.

Effectiveness and Safety of CT-Guided Facet Joint Cyst Rupture for Radicular Pain as First Choice Therapy: A Retrospective Analysis.

OBJECTIVE: To evaluate effectiveness and safety of computed tomography (CT)-guided cyst rupture with intraarticular contrast-enhanced injection of steroid and local anesthetic as first choice therapy in patients with facet joint cyst-induced radicular pain. DESIGN: Retrospective data set analysis. SETTING: University hospital. SUBJECTS: One hundred and twenty-one patients suffering from radicular pain attributable to facet joint cysts were included. METHODS: The rate of patients without following surgery was assessed and defined as surrogate to measure effectiveness. Patients' characteristics, procedure-associated complications, technical aspects, and imaging findings on magnetic resonance imaging (MRI) were analyzed. A subgroup of 65 patients (54%) underwent telephone interview to assess pain relief and clinical outcome measured by Numeric Rating Scale and Oswestry Disability Index. Analyses between the groups with and without surgery were performed by Fisher exact test and two-sample unpaired t-test, respectively. RESULTS: The effectiveness of CT-guided cyst rupture was found to be 66.1%. Procedure-induced pain yielded in premature abort in two cases (1.7%). The detection of epidural contrast agent was statistically significantly associated with no need for surgery (P = .010). The cyst level was associated with the status of following surgery (P = .026), that is, cysts at lower lumbar spine were easier to rupture than cysts at other locations (cervical, thoracic, or upper lumbar spine). No further significant association was found. CONCLUSIONS: CT-guided cyst rupture as the first-choice therapy in patients with cyst-induced radicular pain was safe and effective. Successful cyst rupture was associated with no need for surgery. Cysts at lower lumbar spine revealed the highest success rate.

The Value of APTw CEST MRI in Routine Clinical Assessment of Human Brain Tumor Patients at 3T.

BACKGROUND: With fast-growing evidence in literature for clinical applications of chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI), this prospective study aimed at applying amide proton transfer-weighted (APTw) CEST imaging in a clinical setting to assess its diagnostic potential in differentiation of intracranial tumors at 3 tesla (T). METHODS: Using the asymmetry magnetization transfer ratio (MTRasym) analysis, CEST signals were quantitatively investigated in the tumor areas and in a similar sized region of the normal-appearing white matter (NAWM) on the contralateral hemisphere of 27 patients with intracranial tumors. Area under curve (AUC) analyses were used and results were compared to perfusion-weighted imaging (PWI). RESULTS: Using APTw CEST, contrast-enhancing tumor areas showed significantly higher APTw CEST metrics than contralateral NAWM (AUC = 0.82; p < 0.01). In subgroup analyses of each tumor entity vs. NAWM, statistically significant effects were yielded for glioblastomas (AUC = 0.96; p < 0.01) and for meningiomas (AUC = 1.0; p < 0.01) but not for lymphomas as well as metastases (p > 0.05). PWI showed results comparable to APTw CEST in glioblastoma (p < 0.01). CONCLUSIONS: This prospective study confirmed the high diagnostic potential of APTw CEST imaging in a routine clinical setting to differentiate brain tumors.

Evidence for the Vascular Origin of Benign Enhancing Foramen Magnum Lesions via Intraoperative Photographs: Case Report and Review of the Literature.

A small, benign enhancing lesion posterior to the intracranial vertebral artery at the foramen magnum is a recently described image-based entity and believed to represent varix or ganglion. We report on an individual who underwent surgery due to a hybrid neurofibroma/schwannoma of the trigeminal nerve and additionally presented a small gadolinium-enhancing lesion in the right spinal canal at the level of the craniocervical junction (CCJ). The intraoperative finding of this enhancing lesion most likely represents the lateral internal vertebral venous plexus which does not require follow up or surgical excision.

Thin Slices and Maximum Intensity Projection Reconstructions Increase Sensitivity to Hyperdense Middle Cerebral Artery Sign in Acute Ischemic Stroke.

INTRODUCTION: Cranial nonenhanced CT (NECT) imaging in hyperacute ischemic stroke is rarely used for assessing arterial obstruction of middle cerebral artery by identifying hyperdense artery sign (HAS). Considering, however, its growing importance due to its impact on the decision-making process of thrombolysis with or without mechanical thrombectomy improved sensitivity to HAS is necessary, particularly in the group of less experienced clinicians being frequently the first one assessing the presence of HAS on NECT. OBJECTIVE: The present study aimed to investigate the effect of different NECT image reconstructions on the correct detection of hyperdense middle cerebral artery sign in a cohort of observers with lower experience level on NECT. Particularly, MIP image reconstructions were expected to be useful for less experienced observers due to both strengthening of the hyperdensity of HAS and streamlining to less image slices. METHODS: Twenty-five of 100 patients' NECT image data presented with HAS. Sixteen observers with lower practice level on NECT (10 radiologists and 6 neurologists) evaluated independently the 3 image reconstructions of each data set with thin slice 1.5 mm, thick slab 5 mm, and 6-mm maximum intensity projection (MIP) and rated the presence of HAS in middle cerebral artery. A GEE model with random observer effect was used to examine the influence of the 3 image reconstructions on sensitivity to HAS. A linear mixed effects regression model was used to investigate the ranking of detectability of HAS. Interrater reliability was determined by Fleiss' kappa coefficient (κ). RESULTS: Recognition of HAS and sensitivity to HAS significantly differed between the 3 image reconstructions (p = 0.0106). MIP and thin slice reconstructions yielded each on average the highest sensitivities with 73% compared to thick slab reconstruction with 45% sensitivity. The interobserver reliability was fair (κ, 0.3-0.4). Detectability of HAS was significantly easier and better visible ranked on MIP and thin slice reconstructions compared to thick slab (p < 0.05). CONCLUSION: MIP and thin slice reconstructions increased the sensitivity to HAS (73%), whereas thick slab reconstructions seemed to be less appropriate (45%).

Emergency carotid artery revascularization using Casper-RX stent: A single-center experience.

BACKGROUND: Casper-RX (MicroVention, Aliso Viejo, California, USA) is a dual-layer closed cell stent recently introduced as a carotid artery revascularization device. Although its effectiveness and safety has been proved in elective cases, there are contradictive results regarding its patency in emergency settings. The purpose of the study is to present our single-center experience with the Casper-RX stent in the emergency interventions. PATIENTS AND METHODS: Consecutive patients who underwent emergency carotid artery stenting using Casper-RX system with or without additional intracranial thrombectomy between August 2016 and June 2019 at our institution were included. Primary end point was the short-term patency of the carotid stents evaluated before hospital discharge by use of Doppler ultrasonography. RESULTS: Twenty-nine procedures performed on 28 patients were included in the study. All stents were patent on final angiograms. Acute stent occlusion was observed only in one case (3.4%) with a spontaneous cervical internal carotid artery dissection the day after the procedure. In 26 (89.6%) cases, an additional intracranial thrombectomy was performed with a successful recanalization rate of 96.1%. Seven adverse events occurred peri-/post-procedural: two cases (6.9%) with iatrogenic dissection of distal cervical internal carotid artery during intracranial thrombectomy, two parenchymal hematoma type 2 (6.8%), and three patients (10.3%) developed massive infarction. CONCLUSION: This study supports the safety and efficacy of the Casper-RX stent in emergency endovascular carotid artery revascularization procedures.

Improving resolution of head and neck CTA using the small x-ray tube focal spot.

CT-resolution depends on tube focal spot size. To investigate the effect of reducing focal spot on vessel wall clarity, 22 patients underwent head and neck CTA acquisition with large and small focal spot size. Hounsfield density profile was assessed for each head and neck vessel separately, and significantly sharper density increase at vessel borders was observed using smaller tube focus by an average of 9.9% to 82° angle degrees (p < .05). In conclusion, spatial resolution of CTA of head and neck vessels can be improved by using the small x-ray tube focal spot.

Hyperconnective and hypoconnective cortical and subcortical functional networks in multiple system atrophy.

INTRODUCTION: In multiple system atrophy (MSA), the organization of the functional brain connectivity within cortical and subcortical networks and its clinical correlates remains to be investigated. METHODS: Whole-brain based 'resting-state' fMRI data were obtained from 22 MSA patients (11 MSA-C, 11 MSA-P) and 22 matched healthy controls, together with standardized clinical assessment and video-oculographic recordings (EyeLink®). RESULTS: MSA patients vs. controls showed significantly higher ponto-cerebellar functional connectivity and lower default mode network connectivity (p < .05, corrected). No differences were observed in the motor network and in the control network. The higher the ponto-cerebellar network functional connectivity was, the more pronounced was smooth pursuit impairment. CONCLUSION: This functional connectivity analysis supports a network-dependent combination of hyper- and hypoconnectivity states in MSA, in agreement with adaptive compensatory responses (hyperconnectivity) and a function disconnection syndrome (hypoconnectivity) that may occur in a consecutive sequence.

Regional microstructural damage and patterns of eye movement impairment: a DTI and video-oculography study in neurodegenerative parkinsonian syndromes.

Characteristic alterations of eye movement control are a common feature of neurodegenerative parkinsonism, including Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA). Regional microstructural alterations as assessed by diffusion tensor imaging (DTI) have been reported in PD, PSP, and MSA. Therefore, we investigated the specific association between eye movement disturbances and microstructural impairment in these diseases. Video-oculographic recordings of smooth pursuit and visually guided reactive saccades as well as fractional anisotropy (FA) maps computed from whole-brain DTI data were analyzed for 36 PD, 30 PSP, 18 MSA patients, and 23 matched healthy control subjects. In PSP, peak eye velocity was pathologically slowed compared to controls (p < 0.001) and correlated significantly with microstructural impairment in the midbrain (p < 0.001, corrected). Smooth pursuit eye movements were substantially disturbed in MSA mainly by characteristic 'catch-up' saccades resulting in significantly reduced pursuit gain (p < 0.001, corrected), and the shape of saccadized pursuit in MSA was significantly correlated with FA reductions in the middle cerebral peduncle (p < 0.001, FDR corrected). The prevalence of saccadic intrusions as a measure for inhibitory control was significantly increased in PD compared with controls (p < 0.001), but was uncorrelated with FA in cortical and subcortical white matter. Eye movement disturbances in PSP and MSA-but not in PD-are associated with diagnosis-specific regional microstructural alterations in the white matter. The non-invasive quantified oculomotor function analysis can give clues to the underlying structural connectivity network pathology and underpins its role as a technical marker in PSP and MSA.

Intrinsic functional connectivity alterations in progressive supranuclear palsy: Differential effects in frontal cortex, motor, and midbrain networks.

BACKGROUND: The topography of functional network changes in progressive supranuclear palsy can be mapped by intrinsic functional connectivity MRI. The objective of this study was to study functional connectivity and its clinical and behavioral correlates in dedicated networks comprising the cognition-related default mode and the motor and midbrain functional networks in patients with PSP. METHODS: Whole-brain-based "resting-state" functional MRI and high-resolution T1-weighted magnetic resonance imaging data together with neuropsychological and video-oculographic data from 34 PSP patients (22 with Richardson subtype and 12 with parkinsonian subtype) and 35 matched healthy controls were subjected to network-based functional connectivity and voxel-based morphometry analysis. RESULTS: After correction for global patterns of brain atrophy, the group comparison between PSP patients and controls revealed significantly decreased functional connectivity (P < 0.05, corrected) in the prefrontal cortex, which was significantly correlated with cognitive performance (P = 0.006). Of note, midbrain network connectivity in PSP patients showed increased connectivity with the thalamus, on the one hand, whereas, on the other hand, lower functional connectivity within the midbrain was significantly correlated with vertical gaze impairment, as quantified by video-oculography (P = 0.004). PSP Richardson subtype showed significantly increased functional motor network connectivity with the medial prefrontal gyrus. CONCLUSIONS: PSP-associated neurodegeneration was attributed to both decreased and increased functional connectivity. Decreasing functional connectivity was associated with worse behavioral performance (ie, dementia severity and gaze palsy), whereas the pattern of increased functional connectivity may be a potential adaptive mechanism. © 2017 International Parkinson and Movement Disorder Society.

Patterns of increased intrinsic functional connectivity in patients with restless legs syndrome are associated with attentional control of sensory inputs.

INTRODUCTION: Potential alterations of intrinsic functional connectivity in idiopathic restless legs syndrome (RLS) are to be assumed since RLS is considered a network disorder. Whole-brain-based investigation of intrinsic functional connectivity networks including the sensorimotor systems in patients with RLS was compared with matched healthy controls. METHODS: 'Resting-state' functional MRI (1.5 T) from 26 patients with RLS and 26 matched controls were analyzed using standardized seed-based analysis procedures. The motor/sensorimotor, sensory thalamic, ventral and dorsal attention, basal ganglia-thalamic, cingulate, and brainstem networks were used for voxel-based group comparisons between RLS patients and controls. RESULTS: Significantly increased connectivities were observed in the sensory thalamic, ventral and dorsal attention, basal ganglia-thalamic, and cingulate networks in RLS patients, whereas no differences could be demonstrated for the motor/sensorimotor and the brainstem system. The pattern of functional connectivity alterations was positively correlated with increasing symptom severity. CONCLUSIONS: Abnormally increased regional BOLD synchronization appears to be a key feature of intrinsic brain architecture in RLS. Alterations in cortical and sub-cortical functional networks support the notion that the underlying pathophysiology of RLS is beyond the sensorimotor and the brainstem system and may be also associated with altered attentional control of sensory inputs.

Ex post facto assessment of diffusion tensor imaging metrics from different MRI protocols: preparing for multicentre studies in ALS.

Diffusion tensor imaging (DTI) for assessing ALS-associated white matter alterations has still not reached the level of a neuroimaging biomarker. Since large-scale multicentre DTI studies in ALS may be hampered by differences in scanning protocols, an approach for pooling of DTI data acquired with different protocols was investigated. Three hundred and nine datasets from 170 ALS patients and 139 controls were collected ex post facto from a monocentric database reflecting different scanning protocols. A 3D correction algorithm was introduced for a combined analysis of DTI metrics despite different acquisition protocols, with the focus on the CST as the tract correlate of ALS neuropathological stage 1. A homogenous set of data was obtained by application of 3D correction matrices. Results showed that a fractional anisotropy (FA) threshold of 0.41 could be defined to discriminate ALS patients from controls (sensitivity/specificity, 74%/72%). For the remaining test sample, sensitivity/specificity values of 68%/74% were obtained. In conclusion, the objective was to merge data recorded with different DTI protocols with 3D correction matrices for analyses at group level. These post processing tools might facilitate analysis of large study samples in a multicentre setting for DTI analysis at group level to aid in establishing DTI as a non-invasive biomarker for ALS.

Frontal corpus callosum alterations in progressive supranuclear palsy but not in Parkinson's disease.

BACKGROUND: Frontal lobe involvement is considered a clinical and magnetic resonance imaging (MRI) feature in later stages of progressive supranuclear palsy (PSP). OBJECTIVE: Diffusion tensor imaging (DTI) was used to investigate the integrity of frontal pathways in PSP and Parkinson's disease (PD) patients. METHODS: DTI and 3-D MRI were performed in 15 PSP patients (parkinsonism subtype: n = 8; Richardson subtype: n = 7), 15 PD patients, and 18 matched controls. DTI analysis was performed in order to identify differences along frontal white matter structures including the corpus callosum (CC) and was complemented by atlas-based volumetry and planimetry. RESULTS: Significantly reduced regional fractional anisotropy was observed for PSP patients versus controls and PSP versus PD patients, respectively, in frontal areas including the area II of the CC and bilaterally in the callosal radiation. The DTI findings correlated with frontal lobe volumes. These differences were not observed between PD patients and controls. CONCLUSION: DTI identified a PSP-associated microstructural alteration pattern in the frontal lobes and in the CC area II including the corresponding bilateral callosal radiation tracts that could not be identified in both control samples, supporting the prominent PSP-associated frontal involvement as a potential neuroimaging marker.