Neuroradiology

Pearce, Kirsten;Dixon, Luke;D’Arco, Felice;Pujar, Suresh;Das, Krishna;Tahir, Zubair;Tisdall, Martin;Mankad, Kshitij

doi: 10.1007/s00234-020-02448-2pmid: 32435887

Abstract This review updates the radiologist on current epilepsy surgery practice in children, with a specific focus on the role of imaging in pre-surgical work-up, current and novel surgical techniques, expected post-surgical imaging appearances and important post-operative complications. A comprehensive review of the current and emerging international practices in paediatric epilepsy surgical planning and post-operative imaging is provided with details on case-based radiological findings. A detailed discussion of the pathophysiology and imaging features of different epileptogenic lesions will not be discussed as this is not the objective of this paper. Epilepsy surgery can be an effective method to control seizures in certain children with drug-resistant focal epilepsy. Early surgery in selected appropriate cases can lead to improved cognitive and developmental outcome. Advances in neurosurgical techniques, imaging and neuroanaesthesia have driven a parallel expansion in the array of epilepsy conditions which are potentially treatable with surgery. The range of surgical options is now wide, including minimally invasive ablative procedures for small lesions such as hypothalamic hamartomata, resections for focal lesions like hippocampal sclerosis and complex disconnective surgeries for multilobar conditions like Sturge Weber Syndrome and diffuse cortical malformations. An awareness of the surgical thinking when planning epilepsy surgery in children, and the practical knowledge of the operative steps involved will promote more accurate radiology reporting of the post-operative scan.

Dauleac, Corentin; Frindel, Carole; Mertens, Patrick; Jacquesson, Timothée; Cotton, François

doi: 10.1007/s00234-020-02442-8pmid: 32363485

The spinal cord (SC) is a dense network of billions of fibers in a small volume surrounded by bones that makes tractography difficult to perform. We aim to provide a review collecting all technical settings of SC tractography and propose the optimal set of parameters to perform a good SC tractography rendering. The MEDLINE database was searched for articles reporting “spinal cord” “tractography” in “humans”. Studies were selected only when tractography rendering was displayed and MRI acquisition and tracking parameters detailed. From each study, clinical context, imaging acquisition settings, fiber tracking parameters, region of interest (ROI) design, and quality of the tractography rendering were extracted. Quality of tractography rendering was evaluated by several objective criteria proposed herein. According to the reported studies, to obtain a good tractography rendering, diffusion tensor imaging acquisition should be performed with 1.5 or 3 Tesla MRI, in the axial plane, with > 20 directions; b value: 1000 s mm−2; right-left phase-encoding direction for cervical SC; isotropic voxel size; and no slice gap. Concerning the tracking process, it should be performed with determinist approach, fractional anisotropy threshold between 0.15 and 0.2, and curvature threshold of 40°. ROI design is an essential step for providing good tractography rendering, and their placement has to consider partial volume effects, magnetic susceptibility effects, and motion artifacts. The review reported herein highlights that successful SC tractography depends on many factors (imaging acquisition settings, fiber tracking parameters, and ROI design) to obtain a good SC tractography rendering.

Cocozza, Sirio; Pontillo, Giuseppe; De Michele, Giovanna; Perillo, Teresa; Guerriero, Elvira; Ugga, Lorenzo; Salvatore, Elena; Galatolo, Daniele; Riso, Vittorio; Saccà, Francesco; Quarantelli, Mario; Brunetti, Arturo

doi: 10.1007/s00234-020-02427-7pmid: 32285148

PurposeA new form of autosomal dominant hereditary spinocerebellar ataxia (SCA) has been recently described (SCA48), and here we investigate its conventional MRI findings to identify the presence of a possible imaging feature of this condition.MethodsIn this retrospective observational study, we evaluated conventional MRI scans from 10 SCA48 patients (M/F = 5/5; 44.7 ± 7.8 years). For all subjects, atrophy of both supratentorial and infratentorial compartments were recorded, as well as the presence of possible T2-weighted imaging (T2WI) signal alterations.ResultsIn SCA48 patients, no meaningful supratentorial changes were found, both in terms of volume loss or MRI signal changes. Atrophy of the cerebellum was present in all cases, involving both the vermis and the hemispheres, but particularly affecting the postero-lateral portions of the cerebellar hemispheres. In all patients, with the exception of only one subject (90.0% of the cases), a T2WI hyperintensity of both dentate nuclei was found. The association of such signal alteration with the pattern of cerebellar atrophy resembled the appearance of a crab (“crab sign”).ConclusionOur findings suggest that SCA48 patients are characterized by cerebellar atrophy, mainly involving the postero-lateral hemisphere areas, along with a T2WI hyperintensity of dentate nuclei. We propose that the association of such signal change, along with the atrophy of the lateral portion of the cerebellar hemispheres, resembled the appearance of a crab, and therefore, we propose the “crab sign” as a neuroradiological sign present in SCA48 patients.

Piccirilli, Eleonora; Gentile, Luigia; Mattei, Peter A.; Maruotti, Valerio; Briganti, Chiara; Panara, Valentina; Caulo, Massimo

doi: 10.1007/s00234-020-02430-ypmid: 32306053

PurposeThe head of the hippocampus (H) is classically described as having two to four digitations both in ex vivo specimens and in vivo MR coronal images. The aim of this study was to develop and evaluate a new MR-based classification of the anatomical variants of the hippocampal head in a large sample population of healthy subjects.MethodsMR images of the brain of 238 young healthy subjects (138 men and 100 women; age range 18–39) were analyzed. The head of the H was identified on coronal reformatted 3D T1 weighted MR images. The frequencies were reported for hemisphere and sex. Inter-rater reliability was assessed.ResultsEight variants of the hippocampal head were described. Class 0 (11.4%) indicated a total absence of sulci. This class was further subdivided as follows: 0A (one digitation, 10.1%) and 0B (no digitations or “null variant”, 1.3%). Class 1 (25.6%) presented a single sulcus and was further subdivided into four types according to the location and the width of the sulcus [1A (8.8%), 1B (12.8%), 1C (1.3%), and 1D (2.7%)]. Class 2 (63.0%, the most frequent and the classical variant) had two symmetrical sulci and three digitations. Statistically significant differences between the two hemispheres were observed only in women and overall. Differences in prevalence between sexes were not observed.ConclusionsThe large study population allowed the description of a novel morphological classification of the different anatomical variants of normal H in the coronal plane. This classification could reduce the risk of misinterpreting normal anatomical variants as pathological.

Keil, Vera C.; Borger, Valeri; Purrer, Veronika; Groetz, Simon F.; Scheef, Lukas; Boecker, Henning; Schild, Hans H.; Kindler, Christine; Schmitt, Angelika; Solymosi, Laszlo; Wüllner, Ullrich; Pieper, Claus C.

doi: 10.1007/s00234-020-02433-9pmid: 32363482

PurposeMagnetic resonance-guided focused ultrasound (MRgFUS) systems are increasingly used to non-invasively treat tremor; consensus on imaging follow-up is poor in these patients. This study aims to elucidate how MRgFUS lesions evolve for a radiological readership with regard to clinical outcome.MethodsMRgFUS-induced lesions and oedema were retrospectively evaluated based on DWI, SWI, T2-weighted and T1-weighted 3-T MRI data acquired 30 min and 3, 30 and 180 days after MRgFUS (n = 9 essential tremor, n = 1 Parkinson’s patients). Lesions were assessed volumetrically, visually and by ADC measurements and compared with clinical effects using non-parametric testing.ResultsThirty minutes after treatment, all lesions could be identified on T2-weighted images. Immediate oedema was rare (n = 1). Lesion volume as well as oedema reached a maximum on day 3 with a mean lesion size of 0.4 ± 0.2 cm3 and an oedema volume 3.7 ± 1.2 times the lesion volume. On day 3, a distinct diffusion-restricted rim was noted that corresponded well with SWI. Lesion shrinkage after day 3 was observed in all sequences. Lesions were no longer detectable on DWI in n = 7/10, on T2-weighted images in n = 4/10 and on T1-weighted images in n = 4/10 on day 180. No infarcts or haemorrhage were observed. There was no correlation between lesion size and initial motor skill improvement (p = 0.99). Tremor reduction dynamics correlated strongly with lesion shrinkage between days 3 and 180 (p = 0.01, R = 0.76).ConclusionIn conclusion, cerebral MRgFUS lesions variably shrink over months. SWI is the sequence of choice to identify lesions after 6 months. Lesion volume is arguably associated with intermediate-term outcome.

Song, Xiaowei; Zhao, Xihai; Liebeskind, David S.; Wang, Lixue; Xu, Wendeng; Xu, Yilan; Hou, Duoduo; Zheng, Zhuozhao; Wu, Jian

doi: 10.1007/s00234-020-02418-8pmid: 32300828

PurposeTo investigate the association between plaque enhancement and stroke recurrence in subjects with intracranial atherosclerosis.MethodsIschemic stroke patients with symptomatic intracranial atherosclerosis were prospectively included and followed in a comprehensive stroke center. Pre- and post-contrast vessel wall images were used to evaluate plaque enhancement. Other established suggestive imaging markers were also acquired simultaneously. Univariate- and multivariate-adjusted Cox proportional hazard regression models were used to determine the association between plaque enhancement and stroke recurrence. Finally, receiver operating characteristic (ROC) curves were used to demonstrate the predictive value of different imaging markers.ResultsOf the 60 subjects included, 12 (20.0%) patients presented with ipsilateral stroke recurrence during the median 12-month follow-up. Cox proportional hazard regression models indicated that plaque enhancement was an independent risk factor associated with stroke recurrence after adjusted covariates, with a hazard ratio (HR) of 14.24 and 95% confidence interval (95% CI) (1.21, 168.11), p = 0.04. In addition, border zone infarction was also statistically significant in predicting stroke recurrence in multi-variable regression (HR = 3.80; 95% CI = 1.04, 13.80; p = 0.04). Collateral status was in marginal significance (HR = 0.25; 95% CI = 0.06, 1.08; p = 0.06). ROC analysis indicated that the area under the curve and 95% CI to identify stroke recurrence are 0.67 (0.51, 0.82) for plaque enhancement and 0.71 (0.54, 0.88) for infarction pattern and collateral status and may increase to 0.82 (0.70, 0.93) by combining the three markers above.ConclusionPlaque enhancement is independently associated with stroke recurrence in subjects with intracranial atherosclerosis and has added value to hemodynamic indicators in predicting stroke recurrence.

Manfrè, Luigi; De Vivo, Aldo Eros; Al Qatami, Hosam; Ventura, Fausto; Zobel, Beomonte; Midiri, Massimo; Chandra, Ronil V.; Carter, Nicole S.; Hirsch, Joshua

doi: 10.1007/s00234-020-02438-4pmid: 32367350

Study designProspective experimental uncontrolled trial.BackgroundLumbar microinstability (MI) is a common cause of lower back pain (LBP) and is related to intervertebral disc degeneration that leads to inability to adequately absorb applied loads. The term “microinstability” has recently been introduced to denote a specific syndrome of biomechanical dysfunction with minimal anatomical change. Trans-facet fixation (TFF) is a minimally invasive technique that involves the placement of screws across the facet joint and into the pedicle, to attain improved stability in the spine.PurposeIn this study, we aimed to evaluate the effectiveness, in terms of pain and disability reduction, of a stand-alone TFF in treatment of patients with chronic low back pain (LBP) due to MI. Moreover, as a secondary endpoint, the purpose was to assess the feasibility and safety of a novel percutaneous CT-guided technique.MethodsWe performed percutaneous CT-guided TFF in 84 consecutive patients presenting with chronic LBP attributable to MI at a single lumbar level without spondylolysis. Pre- and post-procedure pain and disability levels were measured using the visual analogue scale (VAS) and Oswestry Disability Index (ODI).ResultsAt 2 years, TFF resulted in significant reductions in both VAS and ODI scores. CT-guided procedures were tolerated well by all patients under light sedation with a mean procedural time of 45 min, and there were no reported immediate or delayed procedural complications.ConclusionTFF seems to be a powerful technique for lumbar spine stabilization in patients with chronic mechanical LBP related to lumbar MI. CT-guided technique is fast, precise, and safe and can be performed in simple analgo-sedation.

Wang, Yongzhe;Song, Liyuan;Guo, Jian;Xian, Junfang

doi: 10.1007/s00234-020-02455-3pmid: 32430642

Abstract Purpose To evaluate the diagnostic performance of the quantitative parameters derived from diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI in differentiating lacrimal gland pleomorphic adenomas (LGPAs) from lacrimal gland malignant epithelial tumors (LGMETs). Methods Seventy-seven cases with LG epithelial tumors confirmed by histopathology (47 LGPAs and 30 LGMETs) underwent DWI and DCE-MRI. The quantitative parameters including the apparent diffusion coefficient (ADC), the volume transfer constant (Ktrans), the efflux rate constant from the extravascular extracellular space (EES) to blood plasma (Kep), and the extravascular extracellular volume fraction (Ve) were used to differentiate LGPAs from LGMETs. Independent-samples t test was conducted to compare these parameters. The diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis. Results Compared with LGPAs, LGMETs had significantly lower ADC value (1.090 ± 0.169mm2/s) (P < 0.001), higher Ktrans value (0.892 ± 0.517/min) (P = 0.001), and Kep value (1.300 ± 1.131/min) (P = 0.002). ADC as a diagnostic index showed a better diagnostic efficacy in predicting malignant tumors (AUC 0.914, sensitivity 90.0%, specificity 85.1%, and accuracy 87.0%) than Ktrans and Kep alone. The combination of ADC and Ktrans presented the optimal diagnostic performance for the differentiation (AUC 0.938, sensitivity 93.3%, specificity 87.2%, accuracy 89.6%). Conclusion The quantitative parameters including ADC, Ktrans, and Kep derived from DWI and DCE-MRI might be potential imaging biomarkers in differentiating LGPAs from LGMETs. The combination of ADC and Ktrans is superior to other quantitative parameters in distinguishing LGPAs from LGMETs.