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Cross-sectional imaging with computed tomography (CT) and MRI are diagnostic examinations useful in the diagnosis of painful ophthalmologic disorders and their potential complications. CT is a first-line imaging study for suspected orbital infections, particularly useful in differentiating preseptal cellulitis and orbital cellulitis and detecting complications such as orbital abscess. When compared with CT, MRI is better for orbital soft tissue evaluation, particularly useful for optic neuritis, ocular diseases such as endophthalmitis, and invasive fungal rhinosinusitis with orbital involvement. CT angiography is the preferred noninvasive imaging modality for the detection and classification of carotid cavernous fistula.

Low back and neck pain are common and result in significant patient disability and health care expenditure. When conservative treatment fails or worrisome clinical findings are present, magnetic resonance imaging (MRI) is the imaging modality of choice to assess the cause and complicating features of spine pain. There are many potential aetiologies of spine pain with similar clinical presentation, including degenerative changes, infection, and insufficiency and pathologic fractures. MRI allows for the differentiation of these sources of spine pain and potential complicating features, permitting the appropriate direction of therapy.

A 74-year-old woman with primary hyperparathyroidism diagnosed from routine laboratory tests described symptoms of fatigue and difficulty with concentration. During surgical consultation, the cervical and thoracic spine MRI scans from the preceding 10-year period, performed for relapsing-remitting multiple sclerosis, were reviewed. In this clinical context, the slowly enlarging left upper paraesophageal lesion, reported as a lateral proximal esophageal (Killian-Jamieson) diverticulum, was reevaluated for a potential parathyroid adenoma. 99mTc-sestamibi SPECT/CT demonstrated focal uptake in the paraesophageal lesion with surgical resection, confirming it to be a large parathyroid adenoma.

This article discusses instrumented spinal surgeries, the radiologic assessment of spinal fixation hardware, and the potential complications of spinal hardware. Radiography is the standard for the postoperative assessment of spinal hardware. Computed tomography and magnetic resonance imaging play a valuable role in the detection of hardware and postsurgical-related complications such as infection, pseudarthrosis, and malpositioned instrumentation. Familiarity with the normal imaging appearance of implanted spinal hardware along with the expected progression of normal postoperative osseous arthrodesis enables recognition of potential complications and helps facilitate appropriate clinical management.

BACKGROUND AND PURPOSE: Accurate and reliable detection of white matter hyperintensities and their volume quantification can provide valuable clinical information to assess neurologic disease progression. In this work, a stacked generalization ensemble of orthogonal 3D convolutional neural networks, StackGen-Net, is explored for improving automated detection of white matter hyperintensities in 3D T2-FLAIR images. MATERIALS AND METHODS: Individual convolutional neural networks in StackGen-Net were trained on 2.5D patches from orthogonal reformatting of 3D-FLAIR (n = 21) to yield white matter hyperintensity posteriors. A meta convolutional neural network was trained to learn the functional mapping from orthogonal white matter hyperintensity posteriors to the final white matter hyperintensity prediction. The impact of training data and architecture choices on white matter hyperintensity segmentation performance was systematically evaluated on a test cohort (n = 9). The segmentation performance of StackGen-Net was compared with state-of-the-art convolutional neural network techniques on an independent test cohort from the Alzheimer’s Disease Neuroimaging Initiative-3 (n = 20). RESULTS: StackGen-Net outperformed individual convolutional neural networks in the ensemble and their combination using averaging or majority voting. In a comparison with state-of-the-art white matter hyperintensity segmentation techniques, StackGen-Net achieved a significantly higher Dice score (0.76 [SD, 0.08], F1-lesion (0.74 [SD, 0.13]), and area under precision-recall curve (0.84 [SD, 0.09]), and the lowest absolute volume difference (13.3% [SD, 9.1%]). StackGen-Net performance in Dice scores (median = 0.74) did not significantly differ (P = .22) from interobserver (median = 0.73) variability between 2 experienced neuroradiologists. We found no significant difference (P = .15) in white matter hyperintensity lesion volumes from StackGen-Net predictions and ground truth annotations. CONCLUSIONS: A stacked generalization of convolutional neural networks, utilizing multiplanar lesion information using 2.5D spatial context, greatly improved the segmentation performance of StackGen-Net compared with traditional ensemble techniques and some state-of-the-art deep learning models for 3D-FLAIR.

We describe the unique MR imaging characteristics of intraocular perfluoro-n-octane, a liquid used for intraoperative and postoperative tamponade in the context of complex retinal detachment repair, and contrast it with other intraocular pathologies. Because trace amounts of perfluoro-n-octane may be left in the globe postoperatively, it may be confused for other abnormalities, such as foreign bodies or tumors.

A pedagogical review of fluid-attenuated inversion recovery (FLAIR) and double inversion recovery (DIR) imaging is conducted in this article. The basics of the two pulse sequences are first described, including the details of the inversion preparation and imaging sequences with accompanying mathematical formulae for choosing the inversion time in a variety of scenarios for use on clinical MRI scanners. Magnetization preparation (or T2prep), a strategy for improving image signal-to-noise ratio and contrast and reducing T1 weighting at high field strengths, is also described. Lastly, image artifacts commonly associated with FLAIR and DIR are described with clinical examples, to help avoid misdiagnosis. Level of evidence 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1590-1600.

Paediatric skull lesions are commonly identified on imaging. They can be challenging to image, given their location and size, and often require several imaging modalities to narrow down the differential diagnosis. Accurate diagnosis of these lesions is paramount because the clinical therapy can vary tremendously. In this review, we provide a simple and systematic approach to clinical-radiological features of primary skull lesions. We highlight the imaging characteristics and differentiate pathologies based on imaging appearances. We also accentuate the role of cross-sectional imaging in lesion identification and management implications.

Diagnostic imaging has become critical in the care of patients suffering from traumatic or nontraumatic emergent orbital conditions. Multidetector computed tomography (MDCT) has become the standard imaging modality for assessing orbital trauma because of its accurate assessment of orbital skeletal and soft tissues injuries. Contrast-enhanced MR imaging is the first-line examination in the assessment of nontraumatic orbital conditions given its excellent evaluation of the orbital soft tissues. Conventional angiography is necessary in some vascular orbital complications and allows for endovascular treatment. This article discusses the spectrum of orbital pathology encountered in the imaging of orbital trauma and nontraumatic orbital emergencies.

BACKGROUND AND PURPOSE: TSE-based T2-weighted imaging of the spine has long scan times. This work proposes a fast imaging protocol using variable refocusing flip angles, optimized for blurring and specific absorption rate. MATERIALS AND METHODS: A variable refocusing flip angle echo-train was optimized for the spine to improve the point spread function and minimize the specific absorption rate, yielding images with improved spatial resolution and SNR compared with the constant flip angle sequence. Data were acquired from 51 patients (35 lumbar, 16 whole-spine) using conventional TSE and the proposed sequence, with a single-shot variant for whole-spine. Noninferiority analysis was performed to evaluate the efficiency of the proposed technique. RESULTS: The proposed multishot sequence resulted in a 2× shorter scan time with a >1.5× lower specific absorption rate. The variable flip angle sequence was noninferior to the conventional TSE (P < .025) for all image-quality and clinical criteria except signal-to-noise ratio for the lumbar spine protocol. However, mean image scores for the TSE-variable refocusing flip angle were ≥4.3 for all criteria, and concordance analysis showed high agreement (>90%) with the TSE, indicating clinical equivalence. The single-shot sequence resulted in 4× shorter whole-spine scans, and image scores were ≥4.4 for all criteria, attesting to its clinical utility. CONCLUSIONS: We present a fast T2-weighted spine protocol using variable refocusing flip angles, including a single-shot variant. The sequences have better point spread function behavior than their constant flip angle counterparts and, being faster, should be less sensitive to patient motion, often seen in the longer TSE scans.

A 63-year-old woman with epilepsy and chronic headaches was admitted for status epilepticus. A lumbar puncture revealed increased opening pressure of 320 mm H2O and bacterial meningitis. MRI brain demonstrated a partial empty sella, tortuous optic nerve sheaths, flattening of the optic papillae, and numerous prominent arachnoid granulations, consistent with chronic idiopathic intracranial hypertension (IIH), as well as bright CSF signal and brain parenchyma within a left meningoencephalocele (figure, A). A CT cisternogram confirmed communication of the subarachnoid space of the meningoencephalocele with the left sphenoid sinus through a small osseous defect (figure, B). While most CSF leaks are related to trauma, IIH is increasingly recognized as a cause of spontaneous leaks.1,2 While the increased opening pressure may have been due to her acute meningitis, her headache symptoms and MRI findings are suggestive of longstanding intracranial hypertension. Monitoring and medical treatment of IIH must accompany surgical repair to avoid recurrence.2

We report the case of a 15-month-old boy with retinoblastoma who developed exotropia secondary to a right medial rectus infarct after intra-arterial chemotherapy. He had unilateral sporadic group C tumor (International Classification of Retinoblastoma) and was treated with intra-arterial melphalan. One week after the first session of intra-ophthalmic arterial melphalan chemotherapy, he was noted to have orbital congestion, exotropia, and right adduction limitation. Magnetic resonance imaging was suggestive of a right medial rectus infarct. The tumor showed a good response to intra-arterial chemotherapy but the exotropia persisted.