Teaching the Future Radiologist: TED-Inspired Radiology Didactics.

TED (acronym for technology, entertainment and design) conferences are an astonishingly successful modern-day platform for "ideas worth spreading". These continue to engage, enlighten and entertain an ever-expanding audience base. TED speakers highlight simple yet relevant ideas, often challenging entrenched perspectives and proposing hitherto unexplored solutions. In this perspective, the authors propose modeling some aspects of Radiology didactics along certain fundamental principles of TED and outline techniques to accomplish this. We overview how this shift can engage diverse learners and enhance retention of key information. We include evidence on such pedagogical techniques boosting learners' working memory and providing strategies for creative problem solving. Finally, we caution educators against criticisms of the TED format, including prioritizing style over content, "dumbing down" information to make it fit a prescribed format and sometimes offering insufficient scientific rigor.

Prevalence of SLEC-negative spontaneous intracranial hypotension in patients with spinal nerve root sleeve diverticula on MRI.

PURPOSE: While there is thought to be an association between spinal nerve root diverticula (NRD) and spontaneous intracranial hypotension (SIH) without a spinal longitudinal epidural collection (SLEC), it remains unclear what the overall prevalence of SLEC-negative SIH is in patients with NRD on MRI. METHODS: Spine MRI imaging reports from our single institution were electronically screened for instances of NRD over a 9-year period (2016-2023). From these cases, patients with brain MRIs consistent with SIH were also identified. Subsequently, the overall proportion of SLEC-negative SIH was determined as a function of total cases with NRD based on spinal level. RESULTS: In total, 83,843 patients with spinal MRIs were screened which identified 4174 (4.97%) with NRD. From these, there were 1203 cervical, 622 thoracic, and 2979 lumbosacral spine MRIs. In total, 16 patients (0.38%; Standard Error [SE]: 0.48%-0.28%) had a brain MRI compatible with SLEC-negative SIH and met ICHD-3 criteria. Patients with cervical NRD had SIH in 2 cases (0.16%; SE: 0.27%-0.05%). SLEC-negative SIH was present in 11 patients with lumbosacral NRD (0.34%; SE: 0.44%-0.24%). In patients with diverticula in the thoracic spine, 14 (2.3%; SE: 2.8%-1.8%) had SLEC-negative SIH. SLEC-negative SIH was significantly more prevalent in patients with thoracic diverticula compared to those with cervical (p<.0001) or lumbosacral NRD (p<.0001). CONCLUSION: In patients with spinal NRD, concurrent SLEC-negative SIH is present in approximately 0.38% of patients, suggesting that in the vast majority of cases, they are an incidental finding. However, SIH is present in approximately 2.3% of patients with thoracic NRD and may be more specific for leak localization.

Radiological abnormalities in progressive multifocal leukoencephalopathy: Identifying typical and atypical imaging patterns for early diagnosis and differential considerations.

Progressive multifocal leukoencephalopathy (PML) is a rare viral central nervous system (CNS) demyelinating disease primarily associated with a compromised immune system. PML is seen mainly in individuals with human immunodeficiency virus, lymphoproliferative disease, and multiple sclerosis. Patients on immunomodulators, chemotherapy, and solid organ or bone marrow transplants are predisposed to PML. Recognition of various PML-associated typical and atypical imaging abnormalities is critical for early diagnosis and differentiating it from other conditions, especially in high-risk populations. Early PML recognition should expedite efforts at immune-system restoration, allowing for a favorable outcome. This review aims to provide a practical overview of radiological abnormalities in PML patients and address differential considerations.

Stents for progressively symptomatic paediatric intracranial arterial dissection.

Arterial dissection is an uncommon cause of paediatric stroke. Medical therapy remains first-line for treatment. There are few reports of neurovascular stents for paediatric intracranial arterial dissection. Two adolescents presented with neurological deficits and CT angiography concerning for supraclinoid internal carotid artery stenosis. The diagnosis of dissection was secured through a combination of vessel wall MRI and digital subtraction angiography. The patients experienced progressive ischaemic symptoms, despite medical management including anticoagulation, and required stenting. The stents used were a Neuroform EZ and an Atlas. Both patients recovered to Modified Rankin Scale (mRS) 0 and had restored vessel calibre on 6-month follow-up digital subtraction angiography. Neurovascular stents can be used to treat progressively symptomatic intracranial arterial dissections in the paediatric population if medical therapy fails.

Cranial subdural migrating to lumbar subdural space in a toddler.

Migrated spinal subdural haematoma (sSDH) is a significantly uncommon finding. This case involves a paediatric patient representing after cranial trauma with new abnormal gait and leg pain who was found to have a migrated sSDH. Literature review for reported cases of pathogenesis theories, causes and management was performed and summarised in this report. The authors concluded that new abnormal gait and leg pain in a paediatric patient with previous cranial trauma is an indication for spinal MRI if migrated subdural haematoma is suspected. Non-surgical management is generally tolerated, and steroids can be trialled for radiculopathy if clinically indicated.

Bilateral oligodendroglial hamartomas: A rare cause of drug-resistant epilepsy in a pediatric patient.

Intractable or drug-resistant seizures in pediatric patients are often secondary to cortical malformations, hamartomas, or mass lesions. Various subtypes of intracerebral hamartomas, associated with seizure disorders, have been described. In this report, we describe a subtype of intracerebral hamartoma associated with intractable epilepsy in a 10-year-old patient. Initial MR imaging demonstrated a mildly expansile, T2/FLAIR hyperintense, T1 isointense, nonenhancing lesion with blurring of the gray-white junction in the left amygdala. Surgical resection was performed, and pathology confirmed oligodendroglial hamartoma. Patient's seizures recurred after a two-year interval with imaging demonstrating a similar lesion in the right amygdala which in retrospect was also seen on multiple imaging studies. This case report demonstrates the importance of recognizing oligodendroglial hamartomas as a cause of intractable seizures given the imaging findings, distinguishing it from ganglioglioma, dysembryoplastic neuroepithelial tumor, and oligodendroglioma, and the importance of closely looking/searching for contralateral lesions, which has important therapeutic and prognostic implications.

Head and Neck Paragangliomas: An Update on the Molecular Classification, State-of-the-Art Imaging, and Management Recommendations.

Paragangliomas are neuroendocrine tumors that derive from paraganglia of the autonomic nervous system, with the majority of parasympathetic paragangliomas arising in the head and neck. More than one-third of all paragangliomas are hereditary, reflecting the strong genetic predisposition of these tumors. The molecular basis of paragangliomas has been investigated extensively in the past couple of decades, leading to the discovery of several molecular clusters and more than 20 well-characterized driver genes (somatic and hereditary), which are more than are known for any other endocrine tumor. Head and neck paragangliomas are largely related to the pseudohypoxia cluster and have been previously excluded from most molecular profiling studies. This review article introduces the molecular classification of paragangliomas, with a focus on head and neck paragangliomas, and discusses its impact on the management of these tumors. Genetic testing is now recommended for all patients with paragangliomas to provide screening and surveillance recommendations for patients and relatives. While CT and MRI provide excellent anatomic characterization of paragangliomas, gallium 68 tetraazacyclododecane tetraacetic acid-octreotate (ie, 68Ga-DOTATATE) has superior sensitivity and is recommended as first-line imaging in patients with head and neck paragangliomas with concern for multifocal and metastatic disease, patients with known multifocal and metastatic disease, and in candidates for targeted peptide-receptor therapy. Keywords: Molecular Imaging, MR Perfusion, MR Spectroscopy, Neuro-Oncology, PET/CT, SPECT/CT, Head/Neck, Genetic Defects © RSNA, 2022.

Pediatric spine trauma: A comprehensive review.

Trauma to the pediatric spine can manifest as osseous, disco-ligamentous, and/or neurological injuries. Associated mortality is significantly higher than in adults. Injury patterns in children are distinct from those encountered in adults. Although spine radiographs are the first line of diagnosis, they may be challenging to interpret in children due to the difficulty of applying recognized radiographic landmarks to the partially ossified spine. Ligamentous laxity and developmental phenomena also lead to imaging pitfalls. Much of the recent literature on this subject focuses on region-specific injuries or individual entities, and may not be tailored specifically to the radiologist, thereby not stressing key aspects pertinent to the effective performance and successful interpretation of imaging exams. We aim to address this void. We provide a comprehensive review of pediatric spine trauma, outlining the clinical decision tools, imaging protocols including the current American College of Radiology (ACR) appropriateness guidelines, interpretive pitfalls and tips to navigate these pitfalls, and management implications of the spectrum of these injuries. Throughout the text, extensive tables, illustrations and imaging examples reinforce key concepts.

Stents for progressively symptomatic paediatric intracranial arterial dissection.

Arterial dissection is an uncommon cause of paediatric stroke. Medical therapy remains first-line for treatment. There are few reports of neurovascular stents for paediatric intracranial arterial dissection. Two adolescents presented with neurological deficits and CT angiography concerning for supraclinoid internal carotid artery stenosis. The diagnosis of dissection was secured through a combination of vessel wall MRI and digital subtraction angiography. The patients experienced progressive ischaemic symptoms, despite medical management including anticoagulation, and required stenting. The stents used were a Neuroform EZ and an Atlas. Both patients recovered to Modified Rankin Scale (mRS) 0 and had restored vessel calibre on 6-month follow-up digital subtraction angiography. Neurovascular stents can be used to treat progressively symptomatic intracranial arterial dissections in the paediatric population if medical therapy fails.

Bevacizumab in treating the cystic components of pediatric low-grade gliomas: A report of four patients.

Low-grade gliomas (LGG) are among the most common types of brain tumors in children and young adults. These tumors often consist of solid and cystic components. Bevacizumab is a documented treatment for progressive LGG, yet the impact of therapy on the cystic component of these tumors is unknown. We present four patients with prominently cystic LGG treated with bevacizumab at the time of progression. In each case, the cystic component responded to treatment. This is the first known study to investigate bevacizumab's impact on the cystic component of low-grade gliomas.

Long-term Survival After Stereotactic Radiosurgery of Brain Metastases: A Case Series with 10-year Follow-up.

Patients with brain metastases (BRM) generally have a poor prognosis with infrequent long-term outcomes. Four patients treated by stereotactic radiosurgery (SRS) for BRM between 2000 and 2010 with a minimum follow-up of 10 years are described. The mean age was 43.5 years, and these individuals exhibited good performance status at the time of diagnosis of intracranial disease. BRM was solitary or multiple, and the primary malignant tumor originated from the thyroid gland, lung, mediastinum or large intestine. Progression of the original and secondary tumors subsequent to diagnosis and SRS was not observed. Radioimaging of the brain obtained 9 years later in one of the patients who was asymptomatic at follow-up revealed white matter changes; BRM in this individual was treated by tumor resection and cranial irradiation prior to SRS. We contend that extended longevity is not precluded when standard management of BRM is practiced in selected cases.

Imaging of parasitic infections of the central nervous system.

Parasitic infections of the central nervous system (CNS) have increased over the last couple of decades, partly due to a drop in the living conditions of large populations in the world and the AIDS epidemic. Parasitic infections of the CNS are indolent and often life threatening, hence, an early diagnosis is imperative. While brain biopsy and laboratory analysis remain the gold standard for diagnosis, neuroimaging contributes significantly to diagnosis and follow-up. Imaging can demonstrate the extent of infection and complications and possibly, the type of parasitic infection when characteristic features are evident. The disappearance of the parasite or inflammation, gliosis, and/or calcification suggest a therapeutic response. The initial experience of the CT scan has been greatly enhanced by MRI which is currently the imaging modality of choice. This has been due to the greater tissue contrast resolution of MRI and its ability to detect subtle changes in the tissue parenchyma. Advanced techniques such as diffusion-weighted imaging (DWI), perfusion imaging (PI), MR angiography (MRA), and MR spectroscopy (MRS) have been used to improve the sensitivity for characterizing the type, viability, and burden of the parasites and the host tissue response. Additionally, it is possible to demonstrate the complications of the primary infection and those secondary to treatment, in some cases.

Multi-detector-row computed tomography imaging of variant skull base foramina.

Several inconstant skull base foramina can be observed on multi-detector-row computed tomographic studies. These include the meningo-orbital foramen, foramen of Vesalius, canaliculus innominatus, palatovaginal canal, persistent craniopharyngeal canal, transsphenoidal canal, canalis basilaris medianus, and fossa navicularis. Although many of these foramina are simply incidental findings, there may be associated anomalies and important clinical implications. The multi-detector-row computed tomographic features of variant skull base foramina are depicted and discussed in this article.

Preoperative localization of parathyroid adenomas using 4-dimensional computed tomography: a pictorial essay.

Accurate preoperative localization is the key to successful parathyroid surgery in the era of minimally invasive parathyroid surgery. This article presents and discusses the embryologic basis of parathyroid gland and ectopic location and different imaging modalities helpful in diagnosing and localizing parathyroid adenomas and/or hyperplasia. We also aim to review the current surgical concepts in treatment of parathyroid adenomas and/or hyperplasia, the utility of 4-dimensional computed tomography for accurate preoperative localization of hyperfunctioning parathyroid glands, imaging classification of adenomas and/or hyperplasia, and, finally, present some of the limitations of 4-dimensional computed tomography.

Case Series: Long segment extra-arachnoid fluid collections: Role of dynamic CT myelography in diagnosis and treatment planning.

We report five patients in whom spinal MRI revealed extra-arachnoid fluid collections. These spinal fluid collections most likely resulted from accumulation of cerebrospinal fluid (CSF) from a dural leak. The patients presented with either compressive myelopathy due to the cyst or superficial siderosis (SS). All of these fluid collections were long segment, and MRI demonstrated the fluid collections but not the exact site of leak. Dynamic CT myelogram demonstrated the site of leak and helped in the management of these complicated cases. Moreover, we also found that the epicenter of the fluid collection on MRI was different from the location of the leak on a dynamic CT myelogram. Knowledge of these associations can be helpful when selecting the imaging studies to facilitate diagnosis and treatment.

Can permeability measurements add to blood volume measurements in differentiating tumefactive demyelinating lesions from high grade gliomas using perfusion CT?

Tumefactive demyelinating lesions (TDLs) can mimic a neoplasm on conventional imaging and may necessitate biopsy for diagnosis. The purpose of this study was to differentiate TDLs from high grade gliomas based on physiologic (permeability) and hemodynamic (blood volume) parameters using perfusion CT. Five patients who presented with tumefactive enhancing lesions on initial MRI that mimicked a neoplasm underwent perfusion CT. We compared the perfusion CT parameters of these patients with those of 24 patients with high grade gliomas. TDLs showed lower permeability surface area product (PS) (0.8 +/- 0.2 vs 2.4 +/- 1.4 ml/100 g/min, P-value 0.014) and lower cerebral blood volume (CBV) (1.0 +/- 0.2 vs 2.8 +/- 1.2 ml/100 g, P-value 0.006) as compared to high grade gliomas. TDLs show lower PS and CBV as compared to high grade gliomas, to which they can mimic on conventional MR imaging, due to lack of neoangiogenesis and vascular endothelial proliferation and hence perfusion CT can be used to differentiate the two entities.

Imaging response criteria for recurrent gliomas treated with bevacizumab: role of diffusion weighted imaging as an imaging biomarker.

The purpose of this study was to assess the usefulness of diffusion weighted imaging as an additional imaging biomarker for treatment response in recurrent/progressive malignant gliomas treated with bevacizumab alone or in combination with other chemotherapeutic agents. Twenty patients treated with bevacizumab alone or concurrent chemotherapy were followed up with serial MR imaging. Volume and ADC values of contrast enhancing lesion (CEL(vol), CEL(ADC)) and also of non-enhancing lesion (NEL(vol), NEL(ADC)) were obtained. CEL(vol) showed a progressive decrease in non-progressors with a median percentage change of -73.2% (P = 0.001) as compared to -33.4% for progressors by 1 year/last imaging (P = 0.382). NEL(vol) also showed a decrease in non-progressors on follow up imaging though only significant for 3 months follow up (P = 0.042). In progressors, CEL(vol) and NEL(vol) showed initial decrease followed by slight increase by 1 year/last imaging though not significant (P value of 0.382 and 0.46, respectively). CEL(ADC) and NEL(ADC) in non-progressors did not show any statistically significant change though there was slight trend for positive percent change especially for CEL(ADC) by 1 year/last imaging follow up study (P value of 0.077 and 0.339, respectively). Progressors showed a progressive negative percent change of CEL(ADC) and NEL(ADC). In progressors, NEL(ADC) decreased at 6 weeks (P = 0.054), 3 months (P = 0.023) and 1 year/last (P = 0.078) as compared to baseline study and was also statistically significant as compared to non-progressors at 6 weeks (P = 0.047) and 3 months (P = 0.025). CEL(ADC) and NEL(ADC) appear to follow different trends over time for non-progressors and progressors with a stable to slightly progressive increase in non-progressors and a progressive decrease in progressors, especially early on. These findings suggest that DWI may be used as an additional imaging biomarker for early treatment response.

Functional correlates of incoordination in patients with spinocerebellar ataxia 1: a preliminary fMRI study.

The neural (blood oxygenation level dependent) correlates of motor coordination of both hands were studied in adult right-handed volunteers and patients with spinocerebellar ataxia 1 (SCA1), using functional magnetic resonance imaging (fMRI) of the entire brain. Each experimental condition consisted of five sets of alternate pronation and supination tasks for either hand in a prescribed sequence as the active phase followed by a period of rest. An intricate network consisting of sensorimotor cortex, supplementary motor area (SMA), cingulate motor area (CMA), putamina and cerebellum, was identified when the task was performed in healthy volunteers. However, cerebellar activity was largely absent with additional activity in contralateral cortices and in thalami in patients with SCA1. This apparent decoupling of sensorimotor cortical and cerebellar areas during coordinated movement in patients with SCA1, suggests that cortico-cerebellar loops may be malfunctioning in SCA1.

First-pass perfusion computed tomography: initial experience in differentiating recurrent brain tumors from radiation effects and radiation necrosis.

OBJECTIVE: To differentiate recurrent tumors from radiation effects and necrosis in patients with irradiated brain tumors using perfusion computed tomographic (PCT) imaging. METHODS: Twenty-two patients with previously treated brain tumors who showed recurrent or progressive enhancing lesions on follow-up magnetic resonance imaging scans and had a histopathological diagnosis underwent first-pass PCT imaging (26 PCT imaging examinations). Another eight patients with treatment-naïve, high-grade tumors (control group) also underwent PCT assessment. Perfusion maps of cerebral blood volume, cerebral blood flow, and mean transit time were generated at an Advantage Windows workstation using the CT perfusion 3.0 software (General Electric Medical Systems, Milwaukee, WI). Normalized ratios (normalized to normal white matter) of these perfusion parameters (normalized cerebral blood volume [nCBV], normalized cerebral blood flow [nCBF], and normalized mean transit time [nMTT]) were used for final analysis. RESULTS: Fourteen patients were diagnosed with recurrent tumor, and eight patients had radiation necrosis. There was a statistically significant difference between the two groups, with the recurrent tumor group showing higher mean nCBV (2.65 versus 1.10) and nCBF (2.73 versus 1.08) and shorter nMTT (0.71 versus 1.58) compared with the radiation necrosis group. For nCBV, a cutoff point of 1.65 was found to have a sensitivity of 83.3% and a specificity of 100% to diagnose recurrent tumor and radiation necrosis. Similar sensitivity and specificity were 94.4 and 87.5%, respectively, for nCBF with a cutoff point of 1.28 and 94.4 and 75%, respectively, for nMTT with a cutoff point of 1.44 to diagnose recurrent tumor and radiation necrosis. CONCLUSION: PCT may aid in differentiating recurrent tumors from radiation necrosis on the basis of various perfusion parameters. Recurrent tumors show higher nCBV and nCBF and lower nMTT compared with radiation necrosis.

Spinal cord pilomyxoid astrocytoma: an unusual tumor.

We present the imaging findings of a case of spinal pilomyxoid astrocytoma in a 29-year-old woman with history of neck and back pain and weakness of bilateral upper extremities. A contrast-enhanced magnetic resonance (MR) imaging study revealed an extensive intradural extramedullary lesion occupying most of the thecal sac extending from mid cervical up to the lumbosacral region with extensive contrast enhancement. Spinal pilomyxoid astrocytoma is rare with only three reported cases in pediatric population in the literature. This report illustrates the MR findings of an unusual case of intradural extramedullary spinal pilomyxoid tumor in an adult patient.