Colin S. Poon

Radiologic Diagnosis of Cerebral Venous Thrombosis: Pictorial Review

OBJECTIVE Cerebral venous thrombosis is often associated with nonspecific clinical complaints. In addition, the imaging findings are often subtle. Underdiagnosis or misdiagnosis of cerebral venous thrombosis can lead to severe consequences, including hemorrhagic infarction and death. CONCLUSION This article reviews the radiologic findings and diagnostic pitfalls of cerebral venous thrombosis. After completing this article, the readers should have an improved ability to diagnose cerebral venous thrombosis accurately, using the optimal imaging tools to achieve this goal.

Digital Subtraction CT Angiography for Detection of Intracranial Aneurysms: Comparison with Three-dimensional Digital Subtraction Angiography

PURPOSE To evaluate the diagnostic accuracy of digital subtraction computed tomographic (CT) angiography in the detection of intracranial aneurysms compared with three-dimensional (3D) rotational digital subtraction angiography (DSA), as reference standard, in a large cohort in a single center. MATERIALS AND METHODS The study was waived by the institutional review board because of its retrospective nature. A total of 513 patients clinically suspected of having or with known intracranial aneurysms and other cerebral vascular diseases underwent both digital subtraction CT angiography with a dual-source CT scanner and 3D DSA, with a median interval of 1 day; 436 patients (84.9%) had acute subarachnoid hemorrhage at presentation. The sensitivity, specificity, and accuracy of digital subtraction CT angiography in depicting aneurysm were analyzed on a per-patient and per-aneurysm basis, with 3D DSA as the reference standard. The sensitivity, specificity, and accuracy of digital subtraction CT angiography in depicting aneurysms of different diameter (ie, <3 mm, 3-5 mm, 5-10 mm, and >10 mm) and of aneurysms at different locations in the anterior and posterior circulation were calculated. Kappa statistics were calculated to quantify inter- and intrareader variability in detecting aneurysms by using digital subtraction CT angiography for 100 patients. RESULTS Of 513 patients, 106 (20.7%) had no aneurysms, while 407 patients (79.3%) had 459 aneurysms at 3D DSA. Digital subtraction CT angiography correctly depicted 456 (99.3%) of the 459 aneurysms. By using 3D DSA as the standard of reference, the sensitivity and specificity of depicting intracranial aneurysms were 97.8% (398 of 407) and 88.7% (94 of 106), respectively, on a per-patient basis, and 96.5% (443 of 459) and 87.8% (94 of 107), respectively, on a per-aneurysm basis. Digital subtraction CT angiography had sensitivities of 91.3% (42 of 46), 94.0% (140 of 149), 98.4% (186 of 189), and 100% (75 of 75) in depicting aneurysms of less than 3 mm, between 3 mm but less than 5 mm, between 5 mm but less than 10 mm, and 10 mm or greater, respectively, and of 95.8% (276 of 288) and 97.7% (167 of 171) in depicting anterior circulation and posterior circulation aneurysms, respectively. Excellent inter- and intrareader agreement was found on a per-patient (κ=0.900 and 0.939, both P<.001) and per-aneurysm basis (κ=0.846 and 0.921, both P<.001) for the detection of intracranial aneurysms with digital subtraction CT angiography. CONCLUSION Digital subtraction CT angiography has a high sensitivity and specificity in depicting intracranial aneurysms with different sizes and at different locations, compared with 3D DSA.

Automatic bone removal dual-energy CT angiography for the evaluation of intracranial aneurysms.

Purpose: To evaluate the diagnostic accuracy of dual-energy computed tomographic angiography (DE-CTA) in the detection of intracranial aneurysms and to determine whether DE-CTA provides adequate information to guide treatment choice. Materials and Methods: Eighty patients (31 men and 49 women; mean [SD] ages of 52 [9] years) with spontaneous subarachnoid hemorrhage underwent DE-CTA. The performance of DE-CTA was compared with conventional CTA created from average weighted images and digital subtraction angiography (DSA). Sensitivity and specificity for aneurysm detection were determined on a per-patient and per-aneurysm basis. The treatment choice was assessed on the basis of aneurysm neck size and/or the dome/neck ratio. Results: With DSA as reference standard (n = 61; 47 aneurysms in 41 patients), DE-CTA correctly detected 45 aneurysms in 41 patients corresponding to sensitivity and specificity of 100% and 95.0% on a per-patient basis versus 95.7% and 95.0% on a per-aneurysm basis, whereas conventional CTA correctly detected 43 aneurysms in 39 patients corresponding to sensitivity and specificity of 95.1% and 95.0% on a per-patient basis versus 91.5% and 95.0% on a per-aneurysm basis. No statistical difference between DE-CTA and conventional CTA was found for the diagnostic evaluation of intracranial aneurysms. Surgery was performed to treat 38 aneurysms, coiling in 26 aneurysms, stent in one patient, and follow-up in the remaining 5 aneurysms. Dual-energy CTA correctly predicted treatment choice in 44 aneurysms, with 15 aneurysms coiled and 29 aneurysms clipped. Conclusions: Compared with DSA, DE-CTA had a comparable diagnostic accuracy for the detection of intracranial aneurysms, visualization of the morphology of aneurysms at the skull base, and prediction of aneurysm treatment choice in most patients with spontaneous subarachnoid hemorrhage based on this study.

Multidetector CT of Temporal Bone Fractures

Temporal bone fracture is a relatively common finding among trauma patients. Before the development of high-resolution multidetector computed tomography (MDCT) imaging, fractures of the skull base and temporal bone were a challenge to diagnose clinically. With current imaging technology, most such fractures are easily detected, and the challenge now lies in predicting the severity of injury and possible complications. In this review, we discuss the detection and classification of temporal bone fractures, their distinction from pseudofractures, and the role of imaging in establishing prognosis, particularly with respect to complications.

Embryology and Anatomy of the Jaw and Dentition

Radiologists should possess working knowledge of the embryological development and anatomy of the jaw and dentition in order to aid in the diagnosis of both simple and complex disorders that affect them. Here, we review the elaborate process of odontogenesis, as well as describe in detail the anatomy of a tooth and its surrounding structures.

Long-and short-range functional connectivity density alteration in non-alcoholic cirrhotic patients one month after liver transplantation: A resting-state fMRI study

PURPOSE To longitudinally evaluate long- and short-range functional connectivity density (FCD) alteration in cirrhotic patients one month after liver transplantation (LT) and their correlation with cognitive changes by using resting-state functional magnetic resonance imaging (rs-fMRI). METHODS Twenty seven candidates awaiting LT and 24 age-, gender-, and education-matched healthy controls (HCs) were studied. All 27 patients and HCs performed rs-fMRI examinations. Of 27 cirrhotic patients, 13 patients received LT underwent the repeated rs-fMRI examinations one month after LT. Laboratory and psychometric tests were carried out. The long- and short-range FCD maps derived from degree centrality calculation were compared. Correlations between FCD alteration and laboratory/psychometric changes were evaluated as well. RESULTS In cirrhotic patients, most of the brain areas with altered long- and short-range FCD could reverse one month after LT, which was accompanied with cognitive and liver functional improvement. The reduced long-range FCD in right posterior cingulate cortex (PCC) and Left middle frontal gyrus (MFG), and reduced short-range FCD in right precuneus (PCu) persisted in the early period after LT. In addition, one month after LT, the post-LT group showed reduced long-range FCD in right rectus gyrus (REC) and left medial prefrontal cortex (MPFC), and reduced short-range FCD in left middle temporal gyrus (MTG), when compared with the pre-LT group. We found Δdigital symbol test (ΔDST) score positively correlated with long-range ΔFCD in right precentral gyrus (preCG) (r = 0.72, P < 0.01) and right supplementary motor area (SMA) (r = 0.59, P < 0.05). CONCLUSION LT results in favorable effect on cognitive function in cirrhotic patient, which can be reflected by FCD alteration. However, persistence of PCC/PCu functional connectivity disturbance one month after LT indicates complete cognitive function restoration may need a longer time.

Orbital lesions: differentiating vascular and nonvascular etiologic factors.

OBJECTIVE Using a number of interesting cases, we illustrate how attention to vascular anatomic features and blood flow patterns can facilitate the diagnosis of an orbital lesion. True vascular lesions can be differentiated from nonvascular mimics, and normal variants of the orbital blood flow pattern can be differentiated from pathologic alterations. CONCLUSION Accuracy of radiologic diagnosis can be improved by an understanding of orbital vascular anatomy and blood flow patterns and with optimal use of imaging techniques.

CRISPS: A Pictorial Essay of an Acronym to Interpreting Metastatic Head and Neck Lymphadenopathy

Lymph node metastasis in head and neck cancer isa significant prognostic indicator that has a major impactboth on treatment planning and patient survival [1]. Becauseaggressive treatment for primary malignancy has becomemore advanced, patients often live long enough to experienceeither recurrence or distant metastasis. Nodal disease and,particularly, its presence on first presentation is the mostreliable predictor for both of these phenomena [2e5]. Withregard to the natural history of this head and neck cancer, themost common sites of metastasis from positive cervicallymph nodes are the lungs, bones, and liver [6].The rate of metastasis varies among different areas of theaerodigestive tract. For instance, T3/T4 carcinomas of theoral cavity, oropharynx, hypopharynx, and supraglotticlarynx exhibit ipsilateral nodal metastasis at a rate of higherthan 50% [7]. The rate of either bilateral or contralateralnodal metastasis ranges from 2%-35% [8,9]. Radiologicidentification of nodal disease thus is critical to guidesurgical decision making regarding neck dissection becauseimaging has been shown to identify metastasis in 7.5%-19%of clinically silent nodes [2,3,9].The identification of nodal disease is important withregard to both the pre- and posttreatment stages. Pretreat-ment imaging has been shown to identify areas of involve-ment in the retropharyngeal, high level II, low level IV, lowlevel V, and level VI/VII nodes [7]. As a result, pretreatmentcomputed tomography (CT) or magnetic resonance imaging(MRI) has become a mainstay of the care plan for patientswith head and neck cancer. The wide acceptance of theradiologic definition of nodal levels has expedited thistransition. Diseased lymph nodes are identified radiologi-cally by their clustering, roundness (shape), inhomogeneity,size, and periphery (extracapsular spread). In addition,the radiologist should be familiar with the most probablesentinel nodes for a given malignancy. For this reason, wepropose the acronym ‘‘CRISPS’’ (clustering, rounded shape,inhomogeneity, size, periphery, sentinel location) asa comprehensive and easy-to-remember mnemonic to aid theradiologist in identifying nodal involvement in patients withhead and neck cancer.Contrast-enhanced CT represents the ideal modalityfor the assessment of metastatic lymphadenopathy, followedclosely by magnetic resonance (MR) pulse sequences(unenhanced T1 or T2 with fat saturation) [10]. Positronemission tomographyeCT possesses the advantage ofmetabolic correlation, which can aid both in the setting ofequivocal findings and distant disease. However, challenges

Cerebral venous thrombosis: state of the art diagnosis and management

PurposeThis review article aims to discuss the pathophysiology, clinical presentation, and neuroimaging of cerebral venous thrombosis (CVT). Different approaches for diagnosis of CVT, including CT/CTV, MRI/MRV, and US will be discussed and the reader will become acquainted with imaging findings as well as limitations of each modality. Lastly, this exhibit will review the standard of care for CVT treatment and emerging endovascular options.MethodsA literature search using PubMed and the MEDLINE subengine was completed using the terms “cerebral venous thrombosis,” “stroke,” and “imaging.” Studies reporting on the workup, imaging characteristics, clinical history, and management of patients with CVT were included.ResultsThe presentation of CVT is often non-specific and requires a high index of clinical suspicion. Signs of CVT on NECT can be divided into indirect signs (edema, parenchymal hemorrhage, subarachnoid hemorrhage, and rarely subdural hematomas) and less commonly direct signs (visualization of dense thrombus within a vein or within the cerebral venous sinuses). Confirmation is performed with CTV, directly demonstrating the thrombus as a filling defect, or MRI/MRV, which also provides superior characterization of parenchymal abnormalities. General pitfalls and anatomic variants will also be discussed. Lastly, endovascular management options including thrombolysis and mechanical thrombectomy are discussed.ConclusionsCVT is a relatively uncommon phenomenon and frequently overlooked at initial presentation. Familiarity with imaging features and diagnostic work-up of CVT will help in providing timely diagnosis and therapy which can significantly improve outcome and diminish the risk of acute and long-term complications, optimizing patient care.

Investigation of thyroid nodules: A practical algorithm and review of guidelines

High resolution ultrasound has led to early detection of subclinical tumors and drastic increase in incidence of thyroid malignancy. To achieve a balance in appropriate investigation without perpetuating an overdiagnosis phenomenon, a concise set of evidence‐based recommendations to stratify risk is required.