Publications by authors named "Ian Mark"

Torus palatinus is an osseus exostosis found in the midline of the hard palate. It is a relatively common condition and is benign in nearly all cases. However, complications such as airway obstruction, sleep apnea, and swallowing difficulties do exist.

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Background And Purpose: Pituitary microadenomas can be challenging to see on MRI, particularly when they are small. The detection of microadenomas commonly relies on contrast-enhanced sequences, highlighting the adenoma that demonstrates hypoenhancement relative to the native pituitary on T1-weighted sequences. Detecting adenomas in patients with Cushing disease is crucial, as surgery is the standard of care treatment.

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Rosai-Dorfman Disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare non-Langerhans cell histiocytic neoplasm. Although the disease classically presents as massive painless lymphadenopathy in young adults, RDD can also involve the central nervous system in some patients. CNS lesions, can cause headaches, neurologic deficits, and even neurologic deficits.

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Background And Purpose: CSF-venous fistulas are a common cause of spontaneous intracranial hypotension. The diagnosis and precise localization of these fistulas hinges on specialized myelographic techniques, which mainly include decubitus digital subtraction myelography and decubitus CT myelography (using either energy integrating or photon counting detector CT). A previous case series showed that cone beam CT myelography, performed as an adjunctive tool with digital subtraction myelography, increased the detection of CSF-venous fistulas.

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Spinal CSF leak care has evolved during the past several years due to pivotal advances in its diagnosis and treatment. To the reader of the (), it has been impossible to miss the exponential increase in groundbreaking research on spinal CSF leaks and spontaneous intracranial hypotension (SIH). While many clinical specialties have contributed to these successes, the neuroradiologist has been instrumental in driving this transformation due to innovations in noninvasive imaging, novel myelographic techniques, and image-guided therapies.

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Background And Purpose: Accurately identifying patients with CSF-venous fistulas (CVF), one cause of spontaneous intracranial hypotension (SIH), is a diagnostic dilemma. This conundrum underscores the need for a CVF biomarker to help select who should undergo an invasive myelogram for further diagnostic workup. Beta trace protein (BTP) is the most abundant CNS derived protein in the CSF and therefore is a potential venous biomarker for CVF detection.

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Post-dural puncture headache is an increasingly recognized cause of chronic headache. Outside of clinical history and myelography that requires an additional dural puncture, there is no reliable diagnostic test to evaluate for persistent dural defects. We describe the injection of iodinated contrast into the dorsal epidural space under CT guidance in 5 patients as a potential tool to visualize persistent dural defects.

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Article Synopsis
  • CSF-venous fistulas (CVFs) are a common cause of spontaneous intracranial hypotension, but they are challenging to detect through imaging methods.
  • Since their identification in 2014, the awareness and diagnosis of CVFs have improved significantly due to collaboration across multiple institutions.
  • This article reviews various imaging techniques for detecting CVFs, highlighting their specific benefits and limitations, and discusses strategies to enhance imaging visibility through specialized positions and techniques.
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Background And Purpose: Intracranial vessel wall imaging is technically challenging to implement, given the simultaneous requirements of high spatial resolution, excellent blood and CSF signal suppression, and clinically acceptable gradient times. Herein, we present our preliminary findings on the evaluation of a deep learning-optimized sequence using T1-weighted imaging.

Materials And Methods: Clinical and optimized deep learning-based image reconstruction T1 3D Sampling Perfection with Application optimized Contrast using different flip angle Evolution (SPACE) were evaluated, comparing noncontrast sequences in 10 healthy controls and postcontrast sequences in 5 consecutive patients.

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Background And Purpose: CSF leaks of the skull base and spine share a common process of CSF volume loss, and yet only the latter has been associated with spontaneous intracranial hypotension (SIH). Despite published claims that only spinal leaks cause SIH, no prior studies have evaluated brain MR imaging in patients with skull base leaks for findings associated with SIH, such as dural enhancement. The purpose of our study was to use a validated brain MR imaging scoring system to evaluate patients with skull base CSF leaks for findings associated with SIH.

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Dilated perivascular spaces (PVSs) are common and easily recognized on imaging. However, rarer giant tumefactive PVSs (GTPVSs) can have unusual multilocular cystic configurations, and are often confused for other pathologic entities, including neoplasms, cystic infarctions, and neuroepithelial cysts. Because GTPVSs are scarcely encountered and even more infrequently operated upon, many radiologists are unaware of the imaging and pathologic features of these lesions.

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Background And Purpose: Feature variability in radiomics studies due to technical and magnet strength parameters is well-known and may be addressed through various preprocessing methods. However, very few studies have evaluated the downstream impact of variable preprocessing on model classification performance in a multiclass setting. We sought to evaluate the impact of Smallest Univalue Segment Assimilating Nucleus (SUSAN) denoising and Combining Batches harmonization on model classification performance.

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Background And Purpose: Spontaneous intracranial hypotension (SIH) is caused by spinal cerebrospinal fluid (CSF) leaks. This study assessed whether the certainty and/or multifocality of CSF leaks is associated with the severity of intracranial sequelae of SIH.

Materials And Methods: A retrospective review was completed of patients with suspected SIH that underwent digital subtraction myelogram (DSM) preceded by brain MRI.

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Intrathecal blood after a percutaneous epidural blood patch is a known complication, one that has been previously attributed to inadvertent needle tip position in the subarachnoid space. We present two cases with imaging confirmation of an alternative mechanism, one that includes blood transferring from the epidural space to the subarachnoid space through a pre-existing dural defect.

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Photon-counting CT is an increasingly used technology with numerous advantages over conventional energy-integrating detector CT. These include superior spatial resolution, high temporal resolution, and inherent spectral imaging capabilities. Recently, photon-counting CT myelography was described as an effective technique for the detection of CSF-venous fistulas, a common cause of spontaneous intracranial hypotension.

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High-grade astrocytoma with piloid features (HGAP) is a recently identified brain tumor characterized by a distinct DNA methylation profile. Predominantly located in the posterior fossa of adults, HGAP is notably prevalent in individuals with neurofibromatosis type 1. We present an image-centric review of HGAP and explore the association between HGAP and neurofibromatosis type 1.

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Background And Purpose: Spontaneous intracranial hypotension is a condition resulting from a leak of CSF from the spinal canal arising independent of a medical procedure. Spontaneous intracranial hypotension can present with normal brain MR imaging findings and nonspecific symptoms, leading to the underdiagnosis in some patients and unnecessary invasive myelography in others who are found not to have the condition. Given the likelihood that spontaneous intracranial hypotension alters intracranial biomechanics, the goal of this study was to evaluate MR elastography as a potential noninvasive test to diagnose the condition.

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Background And Purpose: Spontaneous intracranial hypotension is an increasingly recognized condition. Spontaneous intracranial hypotension is caused by a CSF leak, which is commonly related to a CSF-venous fistula. In patients with spontaneous intracranial hypotension, multiple intracranial abnormalities can be observed on brain MR imaging, including dural enhancement, "brain sag," and pituitary engorgement.

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Background And Purpose: Cushing disease is typically caused by a pituitary adenoma that frequently is small and challenging to detect on conventional MR imaging. High-field-strength 7T MR imaging can leverage increased SNR and contrast-to-noise ratios compared with lower-field-strength MR imaging to help identify small pituitary lesions. We aimed to describe our institutional experience with 7T MR imaging in patients with Cushing disease and perform a review of the literature.

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Historically, MR imaging has been unable to detect a pituitary adenoma in up to one-half of patients with Cushing disease. This issue is problematic because the standard-of-care treatment is surgical resection, and its success is correlated with finding the tumor on imaging. Photon-counting detector CT is a recent advancement that has multiple benefits over conventional energy-integrating detector CT.

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Article Synopsis
  • Photon-counting detector CT myelography offers improved spatial resolution for detecting CSF-venous fistulas but can produce increased noise with sharp kernels and thin slices.
  • A new deep-learning algorithm has been developed to denoise these images, enabling the use of high-quality reconstruction without compromising image clarity.
  • This algorithm, while currently taking 4-6 hours for processing, has the potential to enhance diagnostic sensitivity and improve imaging protocols for better detection of CSF-venous fistulas.
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Background And Purpose: CSF-venous fistulas (CVFs) associated with spontaneous intracranial hypotension (SIH) may have a transient appearance, relative to contrast arrival, which may influence the diagnostic performance of lateral decubitus CT myelography (CTM). We developed a dynamic CTM protocol using real-time bolus-tracking (dCTM-BT) to improve the temporal resolution and standardize the timing of CTM acquisitions post-intrathecal contrast administration. The purpose of our study was to evaluate the feasibility of the dCTM-BT technique and evaluate its diagnostic yield for CVF detection, stratified by brain MRI SIH findings.

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CT myelography has been traditionally used to evaluate post-operative paraspinal fluid collections to discern CSF leaking into a pseudomeningocele versus a contained seroma. Rather than performing a lumbar puncture and injecting intrathecal contrast for myelography, we present the first report of direct contrast injection into a post-operative paraspinal pseudomeningocele for CSF leak confirmation and localization. This is a simple procedure that has several advantages over a conventional CT myelogram for the evaluation of post-operative paraspinal fluid collections.

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As the field of implant dentistry continues to evolve, new techniques and technologies arise that can provide great benefits to the partial or completely edentulous patient. The purpose of this article is to review the history, definition, and rationale of immediate loading of dental implants with the goal of providing evidence-based recommendations for implementation into clinical practice. Relevant literature is summarized and includes discussion regarding prerequisites for immediate loading/restoration of an endosseous implant.

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