Caroline Venstermans

Trauma of the spine and spinal cord: imaging strategies

Traumatic injuries of the spine and spinal cord are common and potentially devastating lesions. We present a comprehensive overview of the classification of vertebral fractures, based on morphology (e.g., wedge, (bi)concave, or crush fractures) or on the mechanism of injury (flexion-compression, axial compression, flexion-distraction, or rotational fracture-dislocation lesions). The merits and limitations of different imaging techniques are discussed, including plain X-ray films, multi-detector computed tomography (MDCT), and magnetic resonance imaging (MRI) for the detection. There is growing evidence that state-of-the-art imaging techniques provide answers to some of the key questions in the management of patients with spine and spinal cord trauma: is the fracture stable or unstable? Is the fracture recent or old? Is the fracture benign or malignant? In summary, we show that high-quality radiological investigations are essential in the diagnosis and management of patients with spinal trauma.

Magnetic Resonance Imaging of the Brain

Magnetic resonance imaging (MRI) examinations of the brain can be performed with several coil types, depending on the design of the MRI unit and the information required. Traditionally, MRI examinations of the brain are performed with quadrature (i.e., circularly polarized) head coils. These volume coils are closely shaped around the head of the patient and usually present a so-called “bird-cage” configuration. Many coils are split in half, for easier patient access and positioning. Recently, phased-array head coils have become the standard of practice for state-of-the-art high-resolution MRI of the brain. Phased-array head coils contain multiple small coil elements, which are arranged in an integrated design which surrounds the head (e.g., 8-, 12- or even 32-channel head coils). Data from the individual coils are integrated by special software to compensate for the nonuniform distribution of the signal-to-noise ratio (SNR) between the peripheral and central parts of the brain. The major advantage of a multichannel, phased-array head coil is that it allows the application of parallel acquisition techniques (PAT), which can be used to speed up MRI. The concept is to reduce the number of phase-encoding steps by switching a field gradient for each phase-encoding step. Skipping, for example, every second phase-encoding line accelerates the acquisition speed by a factor of two. This is called the acceleration or PAT factor. The trade-off for this increased imaging speed is a decrease in SNR. Image reconstruction with PAT techniques is more complicated, and several algorithms have been described, depending on whether image reconstruction takes place before (SMASH, GRAPPA (generalized autocalibrating partially parallel acquisition)) or after (SENSE) Fourier transform of the image data.

Diffusion tensor imaging provides an insight into the microstructure of meningiomas, high-grade gliomas, and peritumoral edema.

Objective Fractional anisotropy (FA) is a measure for the degree of microstructural organization. Several studies have used FA values to assess microstructural organization of brain tumors and peritumoral edema. The purpose of our study was to validate FA and apparent diffusion constant (ADC) values in the diagnosis of meningiomas versus high-grade glial tumors, with the focus on the ability of diffusion tensor imaging (DTI) to reveal tumor ultrastructure. Our hypothesis was that FA and ADC values significantly differ between high-grade gliomas and meningiomas, and in the peritumoral edema. Methods Diffusion tensor imaging values were obtained from 20 patients with meningiomas (21 tumors) and 15 patients with high-grade gliomas. Regions of interest were outlined in FA and ADC maps for solid-enhancing tumor tissue and peritumoral edema. Fractional anisotropy and ADC values were normalized by comparison to normal-appearing white matter (NAWM) in the contralateral hemisphere. Differences between meningiomas and high-grade gliomas were statistically analyzed. Results Meningiomas showed a significantly higher FA tumor/FA NAWM ratio (P = 0.0001) and lower ADC tumor/ADC NAWM ratio (P = 0.0008) compared to high-grade gliomas. On average, meningiomas also showed higher FA values in peritumoral edema than high-grade gliomas (P = 0.016). Apparent diffusion constant values of peritumoral edema for the 2 tumor groups did not differ significantly (P = 0.5). Conclusions Diffusion tensor imaging can be used to reveal microstructural differences between meningiomas and high-grade gliomas and may contribute toward predicting the histopathology of intracranial tumors. We advocate that diffusion tensor imaging should be included in the standard imaging protocol for patients with intracranial tumors.

High-resolution susceptibility-weighted imaging at 3 T with a 32-channel head coil: technique and clinical applications.

OBJECTIVE The purpose of this article is to illustrate the utility of susceptibility-weighted imaging (SWI) as an adjunct to routine MRI of the brain in neurologic disorders. CONCLUSION SWI is a 3D spoiled gradient-echo sequence that combines phase and magnitude information to provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits.

Brain stones revisited—between a rock and a hard place

Objectives and methodsLarge intracranial calcifications are occasionally encountered in routine computed tomography (CT) scans of the brain. These calcifications, also known as “brain stones”, can be classified according to location and aetiology. Combining imaging findings with relevant clinical history and physical examination can help narrow down the differential diagnosis and may allow confident diagnosis in certain situations.ResultsThis article provides a pictorial review illustrating various clinical entities resulting in brain stones.DiscussionBased on location, brain stones can be classified as extra- or intra-axial. Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. Intra-axial brain stones can further be classified according to aetiology, namely neoplastic, vascular, infectious, congenital and endocrine/metabolic. Imaging findings combined with essential clinical information can help in narrowing the differential diagnosis, determining disease state and evaluating effect of therapy.Teaching Points• Based on location, brain stones can be either extra- or intra-axial.• Extra-axial brain stones comprise tumours and exaggerated physiological calcifications.• Intra-axial aetiologies include neoplastic, vascular, infectious, congenital and endocrine/metabolic.• CT scan is the mainstay in identifying and characterising brain stones.• Certain MRI sequences (gradient echo T2* and susceptibility-weighted imaging) are considered adjunctive.

Overview of the Complications and Sequelae in Spinal Infections

Spondylitis or infection of the spine is a spectrum of diseases involving the bone, disks, and/or ligaments. Because of a significant increase in the immunocompromised patient population, spinal infections are a growing and changing group of conditions, making the diagnosis based on imaging more challenging. Most cases of spinal infections are pyogenic and occur after hematogeneous spread of an infection located elsewhere in the body. A prompt diagnosis remains crucial and MR imaging remains the cornerstone in the diagnosis. This article provides a pictorial overview of the complications and sequelae in spinal infections in general. Discussed are postoperative infections, extraspinal spread of infection, fractures and malformations, and neurologic complications.

Medical Imaging of the Lumbar Facet Joint

When evaluating low back pain (LBP), imaging is frequently used to examine patients with specific as well as nonspecific chronic LBP (CLBP). However, the correlation between anatomic abnormalities as seen on imaging, clinical history, and treatment outcomes remains controversial. In some cases, the cause of CLBP cannot be determined with certainty on imaging studies.

Radiologic Imaging of Sports-Induced Brain Injuries

TBI can occur in a wide range of sports activities. Lesions are most commonly caused by impact (contact sports) or activities involving high velocity. Acute sports-related injuries are indistinguishable from head trauma sustained in other accidents. Recurring craniocerebral injuries, such as in sustained in contact sports, can lead to chronic traumatic encephalopathy (CTE). This condition is a tauopathy, which is caused by repetitive mild traumatic brain injury (mTBI). Players of contact sports, such as rugby, hockey, boxing, or American football, have an increased risk of acquiring this condition.

Radiologic Imaging of Spine Injuries

Sports-related spinal injuries can be divided into acute “traumatic” injuries and chronic “overuse” injuries. They mainly occur in sports that either involve high-velocity incidents or falls from heights. In that respect, they do not differ much from other causes of acute spinal injuries. Injuries can be bony with fractures and/or dislocations, soft tissue injuries to ligaments or the disc or spinal cord injuries, and any combination of those.