Localisation of the central sulcus region in glioma patients with three-dimensional fluid-attenuated inversion recovery and volume rendering: comparison with functional and conventional magnetic resonance

Three-Dimensional Volume Rendering: An Underutilized Tool in Neurosurgery

OBJECTIVE

Two-dimensional radiologic images of computed tomography (CT) and magnetic resonance imaging (MRI) examinations are insufficient to provide three-dimensional conception of intracranial or spinal lesions, especially for an inexperienced neurosurgeon. We share our experience of applications of volume rendering (VR) images of CT and MRI studies of brain and spine for the purpose of training and surgical planning in neurosurgery.

METHODS

Digital Imaging and Communications in Medicine viewer software was used on a personal computer/laptop to view CT and MRI examinations of various lesions of brain, spine, and spinal cord. Various user-friendly applications of the software enable users to edit the images acquired.

RESULTS

Imaging technique (CT and MRI) incorporating continuous or overlapping slice with slice thickness of 1 mm with zero gap provides adequate three-dimensional image quality on personal computer/laptop acquired by VR. It was especially helpful for assessment of lesions of the skull base, intracranial vessels (aneurysm and arteriovenous malformation), craniovertebral junction and contrast-enhancing lesions of the brain. Displaying VR images in the operating room as per the patient's head position orients the surgeon to identify various structures in the surgical field.

CONCLUSIONS

VR is underused in neurosurgery. It enables inexperienced neurosurgeons to understand morphologic details of a lesion and important osteoneurovascular structures around it. It is also helpful for training and preoperative planning in selected patients in neurosurgery.

Invisible cortex sign: A highly accurate feature to localize the inferolateral central sulcus

INTRODUCTION

The central sulcus is a key landmark on MRI of the brain, but its inferolateral portion is difficult to identify if unable to trace the sulcus superoinferiorly. The authors observed that the cortex abutting the central sulcus appears isointense to the adjacent white matter on DWI, we named this the 'invisible cortex sign' and our study evaluates whether it could be used to identify the inferolateral central sulcus.

METHODS

Observational study of 108 consecutive 'normal' MRI studies performed from May 2016 to January 2017. A single axial DWI image - obtained in the anterior commissure-posterior commissure plane - was selected from each scan just above the subcentral gyrus such that it included the most inferolateral portion of the central sulcus. These single images were given to 10 readers (neuroradiologists, a neuroradiology fellow and radiology trainees) who marked the central sulcus based on the presence of the 'invisible cortex sign'. Their accuracy in identifying the central sulcus was compared with that of the principal investigators, who used tri-planar T1 volumetric MRI sequences.

RESULTS

One hundred and eight consecutive patients (55 female, 53 male) were selected, ranging from 18 to 81 years old (mean = 40.5, σ = 18.2). The central sulcus was correctly identified in 95.5% of cases (σ = 3.7%; range 89.4-99.1%).

CONCLUSION

The 'invisible cortex sign' is a highly accurate method of identifying the inferolateral central sulcus on a single axial DWI slice without relying on the more superior aspects of the sulcus.

Morphometry of the Hand Knob Region and Motor Function Change in Eloquent Area Glioma Patients

PURPOSE

The hand knob area is the cortical representation of motor hand function. The current study aimed to investigate the effects of eloquent area gliomas on the morphometry of the hand motor cortex and preoperative hand motor function.

METHODS

A retrospective study of 320 glioma patients was conducted. Seventy-eight patients with gliomas involving motor functional area were finally enrolled. Using axial T2-weight magnetic resonance images, the width and height of the hand knob were measured in both hemispheres, and differences were compared between the affected and unaffected hemispheres. Receiver operating characteristic (ROC) curve and logistic regression analysis were used to estimate the degree of correlation between distance measurements and motor impairment.

RESULTS

The width and height of the hand knob in the affected and unaffected hemispheres were significantly different (p < 0.0001). The width, height and distance from the tumor to hand knob were reduced in the functionally impaired group compared to the unimpaired group (p = 0.0003, p < 0.0001, p = 0.0005, respectively). The three parameters were significantly correlated and remained significant in ROC and logistic regression analysis. The optimal cut-off value of width, height and distance for identifying preoperative hand muscle strength were 5.73 mm, 5.80 mm and 5.92 mm, respectively.

CONCLUSION

The morphometry of the hand knob is often changed by the infiltration or extrusion of the tumors that were located in or near the hand knob. The width, height of hand knob and the distance from tumor to hand knob could serve as anatomic biomarkers related to preoperative neurological motor deficits.

The Holy Grail in diagnostic neuroradiology: 3T or 3D?

Many technical developments keep occurring in the field of MRI that could benefit image acquisition in the field of diagnostic neuroradiology. While there is much focus on the potential advantages of 3T and higher field strengths, it is often unclear whether these are cosmetic only, or convey clinically relevant diagnostic value. The increased signal-to-noise at 3T is certainly beneficial in different ways particularly for the acquisition of isotropic 3D sequences like FLAIR. Single-slab 3D sequences can now be obtained with multiple contrasts in clinically attainable data acquisition times and could revolutionize MRI to evolve into a fundamentally multi-planar technique, rather similar to what has happened with the introduction of multi-detector row CT.