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Objectives/hypothesis The objectives of this study were to evaluate the diagnostic accuracy of constructive interference steady state (CISS) sequencing compared to gadolinium-enhanced T1 (GdT1) magnetic resonance imaging (MRI) to screen for small vestibular schwannomas (VSs), and to assess the overall diagnostic confidence of neuroradiologists in their ability to accurately diagnose or rule out VSs using CISS imaging compared to a GdT1 MRI STUDY DESIGN: Retrospective chart review. Methods Chart review from 2011 to 2015 was performed for VS/benign cerebellopontine angle tumors. Two blinded, board-certified neuroradiologists each independently reviewed the axial CISS sequence and answered a set of questions that determined their confidence in diagnosis of VS. Next, each neuroradiologist independently reviewed the corresponding GdT1 MRI sequence and completed the same questionnaire. Results The majority of the lesions were in the lateral internal auditory canal, with eight intralabyrinthine tumors. The overall sensitivity of CISS for both readers was 93.5%. All tumor locations had high sensitivities except for the intralabyrinthine location (62.3%). Four of the eight total intralabyrinthine lesions were missed by at least one reader. Each reader was highly confident in diagnosing VSs with CISS, which approximated that of GdT1 MRI. Conclusions This study's results showed that CISS examinations for screening of small VS approximated that of GdT1. Neuroradiologists had high sensitivity, perfect specificity, and felt confident in ruling out a VS on CISS sequence while feeling extremely confident in diagnosing one on CISS. Intralabyrinthine lesions and lesions ≤3.0 mm are most at risk for not being detected on CISS examinations. Level of evidence 4 Laryngoscope, 128:2128-2132, 2018.

Objective: Evaluate the pathophysiology of contrast extravasation. Methods: Two hundred fifty-five sialograms at the University of Iowa from 2008 to 2016 were reviewed. Results: Twelve sialograms (4.7% of total) were identified with main ductal extravasation. In each case, ductal stenosis as a diagnosis was supported by clinical history and the finding of difficulty in advancing the cannula into the duct during sialography. In all but 1 case, extravasation occurred at the distal duct with no further imaging of the ductal system. Each of the 5 cases treated with sialendoscopy with or without gland resection confirmed stenosis. Ultrasound evaluation of 5 of the cases detected ductal dilation in 4 (80%). Six of 11 computed tomography scans done before the sialogram were interpreted as normal with indirect evidence for ductal stenosis (duct dilation) reported in only 1. All extravasations were associated with either stricture alone or stricture with stone (1 case). Conclusion: Radiocontrast extravasation from the main duct during sialography is highly associated with the presence of ductal stricture. In our experience, the inability to fill the ductal system with radiocontrast is a useful sialographic finding that correlated closely with anatomic abnormality rather than technical error. The frequent finding of extravasation of radiocontrast supports the use of water soluble contrast.

Immunoglobulin G4 (IgG4)-related disease is an immune-mediated disorder that commonly manifests in the salivary glands. As a recently described disorder, the description and classification of IgG4-related disease is an ongoing process. Diagnosis of IgG4-related disease requires integration of clinical history, histopathology, and radiographic findings, including ultrasonography and sialography. In this case report, we correlate parotid ultrasonographic and sialographic findings in a patient with proven IgG4-related disorder confirmed from analysis of previous submandibular gland resections. We aim to highlight the utility of multimodality imaging in the diagnosis of IgG4-related disease.

Background Parotid swelling is rarely caused by pneumoparotitis from retrograde insufflation of air into Stensen's duct. Previous reports have identified occupational exposures, self-induced habits, exercise, spirometry, and short-term positive pressure airway ventilation as causes of salivary duct insufflation. Methods We present 2 cases of pneumoparotitis in patients on long-term oronasal continuous positive airway pressure (CPAP) for obstructive sleep apnea. Results A diagnosis of pneumoparotitis was made by CT scan in case 1 and sialography in case 2. Patients were advised to transition from oronasal to nasal-only CPAP. One patient was successfully transferred and had good symptomatic improvement, whereas the second patient did not tolerate nasal CPAP and had persistent symptoms on oronasal CPAP. Conclusion Long-term use of oronasal CPAP is a potential cause of pneumoparotitis.

Objectives To analyze the location and degree of parotid ductal abnormalities associated with Sjogren's syndrome (SS) and to correlate findings with the duration of the disease. To develop a classification system based on contemporary sialography techniques and employ the system to grade findings on sialograms. To assess the role for therapeutic intervention in patients with SS. Methods Retrospective chart review of a consecutive series of 337 sialograms done by the senior investigator over a 10-year period identified 26 sialograms in patients who met the criteria for SS as defined by the American-European Consensus Group (2002). A classification system was developed to grade the degree of ductal abnormalities identified on the sialograms. Individual, initial blinded review of these sialograms was performed by two head and neck radiologists to identify and grade abnormalities. Radiographic findings were correlated with patient history including symptom duration. Results All patients with SS had stenoses within the ductal system. About 73.1% of patients had stenoses in each branch of the ductal system (primary, secondary, and tertiary ducts). In 19% of patients, the main duct was of normal caliber despite the presence of stenosis in the more proximal ducts (secondary and tertiary ducts). Peripheral (proximal) duct dilation was characterized among those affected in patterns classified as destructive (34.6%), cavitary (26.9%), globular (11.5%), or punctate (11.5%). A statistically significant positive correlation (p = .0360) was identified between symptom duration and degree of main ductal stenosis. Conclusion Sialography may be useful to objectively assess the degree of parotid ductal damage in SS employing a newly proposed classification system. This assessment may assist clinicians in tailoring management to selectively include ductal dilation.

Objective During surgery, shoulder traction is often used for better fluoroscopic imaging of the lower cervical spine. Traction on the C5 root has been implicated as a potential cause of C5 palsy after cervical spine surgery. Using magnetic resonance imaging, this study was undertaken to determine the impact of upper extremity traction on the C5 root orientation. Methods In this study, 5 subjects underwent coronal magnetic resonance imaging of the cervical spine and left brachial plexus. Using a wrist restraint, sequential traction on the left arm with 10, 20, and 30 lb. was applied. Measurements of the angle between the spinal axis and C5 nerve root and the angle between the C5 nerve root and the upper trunk of the brachial plexus were obtained. The measurements were taken by a trained neuroradiologist and analyzed for significance. Results The angle between the C5 nerve root and the vertical spinal axis remained within 3 and 4 degrees of the mean and was not found to be associated with increased traction weight (P = 0.753). The angle between the C5 root and the upper trunk increased with increasing weight and was found to be statistically significant (P = 0.003). Conclusions While the cause of C5 palsy is likely multifactorial, this study provides evidence that, in the awake volunteer, upper extremity traction leads to C5 root and upper trunk tension. These results suggest that shoulder traction in the anesthetized patient could lead to tension of the C5 nerve root and subsequent injury and palsy.

Determining which patients will benefit from reoperation for recurrent glioblastoma remains difficult and the impact of the volume of FLAIR signal hyperintensity is not well known. The primary purpose of this study is to analyze the impact of preoperative volume of FLAIR hyperintensity on prognosis. 37 patients who underwent a reoperation for recurrent glioblastoma after initial gross total resection followed by standard chemoradiation were retrospectively reviewed. Volumetric analysis of preoperative MR images from the initial and second surgery was performed and correlated with clinical data. Survival probabilities were estimated using the Kaplan-Meier method and Cox regression to assess the effect of risk factors on time to reoperation (TTR), progression-free survival (PFS) after reoperation, and overall survival (OS). The volumes of FLAIR signal hyperintensity prior to the initial surgery and reoperation were not associated with prognosis. TTR and OS were significantly affected by the preoperative enhancement volume at the initial surgery, with increasing volumes yielding poorer prognosis. Patients with tumor in critical/eloquent areas were found to have a worse prognosis. Median TTR was 11 months, median PFS after reoperation was 3 months, and OS in patients undergoing a reoperation was 21 months. The results suggest FLAIR signal change seen in patients with glioblastoma does not influence time to reoperation, progression-free survival, or overall survival. These findings suggest the amount of FLAIR signal change should not greatly influence a surgeon’s decision to perform a second surgical resection compare to other factors, and when appropriate, aggressive surgical intervention should be considered.

Background This study was designed to investigate the clinical features and the growth rate of craniofacial osteomas. Methods Retrospective chart review was performed of 200 cases of craniofacial osteomas diagnosed from January 2001 to September 2011. Data pertinent to patient and osteoma lesion characteristics were collected. Histology of operated cases was reviewed. Computer tomography (CT) charts were reviewed and those with multiple images were analyzed for growth characteristics. Results One hundred forty-nine patients met our inclusion criteria. Eighty-nine percent of these osteomas were found incidentally. Forty-three percent were in the frontal sinus. Fifteen percent of the patients complained of headaches and only 6.71% of patients with osteoma had headaches congruent with osteoma location. Thirty-one percent of CT scans had sinus mucosal disease; only 8% had mucosal disease adjacent to the osteoma. Ten of the 149 patients underwent surgery for cosmetic and/or rapidly growing osteomas. Thirteen patients had intestinal tubular adenoma, and one was genetically positive for Gardner's syndrome. Fifty-two patients had multiple CT scans that were included in growth rate analysis. The mean linear growth rate of osteomas was estimated to be 0.117 mm/yr (95% CI, 0.004, 0.230) in maximal dimension, assuming linear growth. A descriptive analysis of osteoma growth divided the osteomas into several intervals and studied the growth rate separately in each interval. The median change in maximum dimension was different in each interval in a nonsystematic manner, ranging from −0.066 mm, over 3- to 9-month interval (interquartile range [IQR] = −0.404–1.069), to 0.369 mm over 9- to 15-month interval (IQR = −0.032–0.855), and 0.082 mm over 45- to 51-month interval (IQR = −0.000–0.197). There was no significant association between tumor size, location, or complications. Conclusion Craniofacial osteomas are slow-growing lesions with no specific growth pattern and rare complications. Their clinical behavior is ill defined and justifies a conservative approach toward asymptomatic lesions with close radiological follow-up.

We present a case of an ectopic mediastinal parathyroid adenoma in a 58-year-old male patient. We show how different imaging modalities were successfully used to reach a diagnosis. We particularly focus on the role of four-dimensional CT scan in preoperative localization of ectopic adenomas and discuss how diverse imaging modalities can be integrated in the workup of ectopic parathyroid adenomas.

Natural language processing (NLP) techniques to extract data from unstructured text into formal computer representations are valuable for creating robust, scalable methods to mine data in medical documents and radiology reports. As voice recognition (VR) becomes more prevalent in radiology practice, there is opportunity for implementing NLP in real time for decision-support applications such as context-aware information retrieval. For example, as the radiologist dictates a report, an NLP algorithm can extract concepts from the text and retrieve relevant classification or diagnosis criteria or calculate disease probability. NLP can work in parallel with VR to potentially facilitate evidence-based reporting (for example, automatically retrieving the Bosniak classification when the radiologist describes a kidney cyst). For these reasons, we developed and validated an NLP system which extracts fracture and anatomy concepts from unstructured text and retrieves relevant bone fracture knowledge. We implement our NLP in an HTML5 web application to demonstrate a proof-of-concept feedback NLP system which retrieves bone fracture knowledge in real time.

Purpose To investigate whether improved clinical history allows the radiologist to better predict the pretest probability of obtaining a positive or negative result from a magnetic resonance (MR) examination. Materials and Methods Six neuroradiologists prospectively reviewed 100 consecutive requests for brain MR examinations and sequentially assessed 1) quality of written history, 2) degree of indication for requested study, and 3) any pertinent new information found during chart review that may have altered the degree of indication. MR yield was correlated with the degree of indication assessed before and after chart review. Results Most request form histories were judged as poor (63%), and chart review reduced the overall indications for MR examinations, as there was a tendency for high-indication requests to migrate to the low-indication category. Based on request form history alone, the yields for low- and high-indication studies were 13% and 37%, respectively. Correlations between MR yield and indication after chart review improved significantly (P < 0.05) with 2% and 61% for low and high indications, respectively. Sensitivity and specificity for a positive MR yield were 71% and 62%, respectively, for the indication judged by the request history alone, and 96% and 80%, respectively, after chart review. Positive and negative prediction rates were 37% and 87%, respectively, for the indication judged by the request history alone, and 61% and 98%, respectively, for the indication judged after chart review. Conclusion Based on our limited data, most request form histories were inadequate, and essential information available in the chart before MR examinations was frequently missing from the request forms. When adequate information was provided, the indication for the studies as judged by the radiologists predicted the MR yield more accurately, particularly for those requests with low indication. Therefore, our study suggests that MR imaging (MRI) may be used more effectively when pertinent clinical history is available. However, our study is limited and further studies are needed to confirm our results. J. Magn. Reson. Imaging 2004;20:228–232. © 2004 Wiley-Liss, Inc.

Rationale and Objectives The purpose of this study was to evaluate residents' use of a radiology curriculum CD-ROM designed to provide ready access to the department's curricula, study materials, and Internet resources.

To compare the interobserver and intermodality differences in image-based identification of head and neck primary site gross tumor volumes (GTV). Modalities compared include: contrast-enhanced CT, F-18 fluorodeoxyglucose positron emission tomography (PET/CT) and contrast-enhanced MRI.Fourteen patients were simulated after immobilization for all 3 imaging modalities (CT, PET/CT, MRI). Three radiation oncologists (RO) contoured GTVs as seen on each modality. The GTV was contoured first on the contrast-enhanced CT (considered the standard), then on PET/CT, and finally on post-contrast T1 MRI. Interobserver and intermodality variability were analyzed by volume, intersection, union, and volume overlap ratio (VOR).Analysis of RO contours revealed the average volume for CT-, PET/CT-, and MRI-derived GTVs were 45cc, 35cc and 49cc, respectively. In 93% of cases PET/CT-derived GTVs had the smallest volume and in 57% of cases MRI-derived GTVs had the largest volume. CT showed the largest variation in target definition (standard deviation amongst observers 35%) compared to PET/CT (28%) and MRI (27%). The VOR was largest (indicating greatest interobserver agreement) in PET/CT (46%), followed by MRI (36%), followed by CT (34%). For each observer, the least agreement in GTV definition occurred between MRIPET/CT (average VOR = 41%), compared to CTPET/CT (48%) and CTMRI (47%).A nonsignificant interobserver difference in GTVs for each modality was seen. Among three modalities, CT was least consistent, while PET/CT-derived GTVs had the smallest volumes and were most consistent. MRI combined with PET/CT provided the least agreement in GTVs generated. The significance of these differences for headneck cancer is important to explore as we move to volume-based treatment planning based on multi-modality imaging as a standard method for treatment delivery.

The aim of this study was to investigate the morphologic changes of the pituitary gland in patients with the clinical diagnosis of idiopathic intracranial hypertension (IIH). Qualitative and quantitative analyses of pituitary morphology were performed in normal subjects (n = 23), patients with the clinical diagnosis of IIH (n = 40), and patients with acute increased intracranial pressure (AICP; n = 37) caused by acute head trauma. The loss of pituitary height (concavity) on the sagittal T1-weighted image was classified into five categories: I = normal, II = superior concavity that was mild ( (2/3) concavity of height of sella), and V = empty sella. The area ratio of pituitary gland to sella turcica measured in the midsagittal plane was quantified. Clinical records were retrospectively reviewed to correlate with magnetic resonance (MR) findings. Using moderate concavity (>(1/3)) as the minimum criterion for abnormality, IIH patients had an 85% incidence of morphologic changes with 80% sensitivity and 92% specificity. Empty sella (almost complete concavity of the sella) was found in only 2.5% of patients with IIH. Quantitative analysis of the pituitary gland/sella turcica area ratio showed a significant decrease in patients with IIH (P < 0.0001) but no significant difference between the normal subjects and AICP patients. A posterior deviation of the pituitary stalk was seen in 43% of patients. No enlargement of the ventricles or sulcal effacement was seen in IIH patients. Routine brain MR examination of patients with IIH frequently shows morphologic changes of the pituitary gland ranging from various degrees of concavity to (rarely) the extreme case of an empty sella. The etiology is unknown and may be related to the severity and duration of elevated CSF pressure. Such findings may be useful to facilitate the diagnosis of IIH, particularly in patients with equivocal clinical findings or when IIH is not suspected. J. Magn. Reson. Imaging 2000;12:808-813.

Functional imaging may come to play an important role in the evaluation of CNS vasculitis by demonstrating pathology on the microcirculatory level. A positive finding of microvascular ischemia may assist in the diagnosis of CNS vasculitis. More importantly, the demonstration of normal microcirculation may reliably exclude CNS vasculitis. J. Magn. Reson. Imaging 1999;10:310–313. © 1999 Wiley-Liss, Inc.

No single dose of MR contrast agent is optimal or adequate for the evaluation of all types of CNS lesions. This article discusses the fundamental principles and various background suppression techniques for lesion detection and delineation. An understanding of all factors influencing lesion conspicuity is important in deciding the optimal dose, if any, of contrast agent and the technique necessary for the procedure.

A 49-year-old white male presented with a pseudo-subarachnoid hemorrhage and diffuse brain edema. Neuroimaging showed brain edema causing the unusual findings of a pseudo-subarachnoid hemorrhage and bilateral occipital lobe infarcts following herniation and compression of the posterior cerebral arteries. An enlarged corpus callosum was noted which led to a brain biopsy and a diagnosis of gliomatosis cerebri.

Clinical experience suggests that the majority of schwannomas arise within sensory ganglia, suggesting that intraganglionic glial cells represent a potential cell of origin for schwannomas. To support this clinical impression, we reviewed magnetic resonance imaging (MRI) studies performed over a 5-year period at our institution to determine the relationship of cranial and spinal nerve schwannomas with the ganglia of the associated nerves.Retrospective cohort study.Tertiary referral center.Patients undergoing imaging study at our institution over a 5-year period.Radiographic images at our institution were reviewed as well as published studies to determine the anatomic location of schwannomas.Anatomic location of schwannomas.A total of 372 patients were found over the 5-year study period, 31 of those were diagnosed with neurofibromatosis Type 2 (NF2). Vestibular schwannomas comprised the greatest number of schwannomas, followed by spinal schwannomas. In NF2 patients, spinal schwannomas were the most common tumor, followed by vestibular schwannomas. In NF2 patients and those with sporadic schwannomas, the overwhelming majority of tumors arose in nerves with a sensory component and were associated with the sensory ganglia of the nerves (562/607, 92.6%). Very few tumors arose from pure motor nerves. This is supported by review of published articles on anatomic location of schwannomas.Schwannomas are strongly associated anatomically with the ganglia of sensory nerves. These findings raise the possibility that intraganglionic glial cells give rise to the majority of schwannomas.

BACKGROUND AND PURPOSE: Several studies have been undertaken to validate quantitative methods of evaluating cervical spinal stenosis. This study was performed to assess the degree of interobserver and intraobserver agreement in the qualitative evaluation of cervical spinal stenosis on CT myelograms and MR images. METHODS: Cervical MR images and CT myelograms of 38 patients were evaluated retrospectively. Six neuroradiologists with various backgrounds and training independently assessed the level, degree, and cause of stenosis on either MR images or CT myelograms. Unknown to the evaluators, 16 of the patients were evaluated twice to determine intraobserver variability. RESULTS: Interobserver agreement among the radiologists with regard to level, degree, and cause of stenosis on CT myelograms showed κ values of 0.50, 0.26, and 0.32, respectively, and on MR images showed κ values of 0.60, 0.31, and 0.22, respectively. Intraobserver agreement with regard to level, degree, and cause of stenosis on CT myelograms showed mean κ values of 0.69, 0.41, and 0.55, respectively, and on MR images showed mean κ values of 0.80, 0.37, and 0.40, respectively. CONCLUSION: MR imaging and CT myelographic evaluation of cervical spinal stenosis by using current qualitative methods results in significant variation in image interpretation.

With the advances and availability of new imaging modalities, the role of imaging of acute stroke has been broadened from making diagnosis to providing valuable information for patient management. We need to have rapid diagnostic modalities that distinguish reversible ischemic tissue from irreversibly damaged tissue for successful thrombolytic therapy. Although diffusion imaging has been reported to have both high sensitivity and specificity for acute ischemia in clinical studies, previous reports do not conclude whether the diffusion abnormality is indicative of reversibly or irreversibly injured tissue. Perfusion imaging such as perfusion magnetic resonance imaging and single-photon emission computed tomography may have the potential for providing useful information that determines tissue viability and/or reversibility. Cerebral blood flow thresholds evaluated by pretreatment single-photon emission computed tomography provide important information that is potentially useful in the management of acute stroke patients with intra-arterial thrombolysis. Perfusion imaging, when combined with diffusion imaging, may thus be potentially useful in improving patient selection for thrombolytic therapy.

The availability of new therapeutic interventions, including neuroprotective agents and endovascular thrombolysis, has given new hope to patients suffering an acute stroke. Early intervention remains a key factor in the effectiveness of these new and traditional treatments. More importantly, the capability to assess the viability and reversibility of the ischemic tissue became essential for better delineation and differentiation of infarcted versus ischemic tissue and patient management. Abnormal MR imaging (MRI) findings during acute stroke usually reflect the underlying pathophysiologic changes, which can be classified into three sequential stages: (a) hypoperfusion, (b) cellular dysfunction and (c) breakdown of the blood-brain barrier. The first stage is a kinetic phenomenon (not biologic) and, therefore, can be detected immediately. Contrast agents accentuate the abnormal flow kinetics and facilitate the early diagnosis of ischemia using either conventional MRI or newly developed echo-planar perfusion imaging (EPPI). The demonstration of abnormal arterial or parenchymal enhancement on conventional MRI during acute stroke provides the earliest sign of vascular occlusion/stenosis. EPPI, in contrast, provides information related to microcirculation (< 100 microns) and tissue reserve (cerebral blood volume) that cannot be obtained by conventional angiography and is directly related to the target end-organ. Further information obtained from both contrast MRI and EPPI may have a predictive value in the clinical outcome of acute stroke patients.

Purpose The radiology externship program at the authors' institution introduces medical students to radiology using a hands-on approach and is tailored to interested third-year medical students. There are currently limited data available on whether the program increases exposure to radiology in a positive fashion and how it influences medical students' education and career choices. Methods In September 2010, current and former externs between 2007 and 2010 were surveyed using an anonymous, Web-based survey. Results The response rates were 100% (11 of 11) for current externs and 52% (15 of 29) for former externs, for an overall response rate of 65% (26 of 40). The respondents included 20 men and 5 women. The average age of respondents was 27.3 ± 2.5 years. Forty-six percent of former externs (6 of 13) had matched to radiology residencies, whereas the remainder had matched to various surgical and nonsurgical subspecialties. Eighty-four percent (21 of 25) had overall positive ratings of the program. Ninety-two percent (23 of 25) felt they had a better understanding of which test was most appropriate to order for common indications, and 88% (22 of 25) felt that they had a better understanding of imaging contraindications. Sixty-eight percent (17 of 25) felt that they had a better understanding of risk-benefit analysis involving imaging using ionizing radiation, and 56% (14 of 25) felt more confident in discussing these matters with their patients. Conclusions This radiology externship program increases exposure to radiology in a positive fashion, increases understanding of the appropriate use of imaging modalities and their associated clinical benefits and risks, and influences medical students' career choices. These results add to the evidence that this type of program is mutually beneficial to medical students, residents, and clinical colleagues and suggest that more medical schools and radiology departments should evaluate the feasibility of starting radiology externship programs.

13003 Background: Improved survival of patients with newly diagnosed malignant glioma has been acheived with the addition of either intracavitary carmustine (BCNU) chemotherapy or oral temozolomide...

Failure to suppress cerebrospinal fluid (CSF) signal intensity (sulcal hyperintensity) on fluid-attenuated inversion recovery (FLAIR) images has been reported in patients with abnormal CSF, such as those with meningitis and subarachnoid hemorrhage. Our study investigates the clinical history and MR findings associated with sulcal hyperintensity on FLAIR images in patients without apparent CSF abnormality.Three hundred consecutive MR imaging examinations were prospectively screened for patients with sulcal hyperintensity on FLAIR images. Nine patients with clinical, CT, or laboratory evidence suggesting abnormal CSF were excluded. The distribution of sulcal hyperintensity on FLAIR images and associated abnormal enhancement were evaluated. The presence of the "dirty CSF" sign (mild increase in CSF signal on unenhanced T1-weighted images or mild decrease on T2-weighted images) in the corresponding hyperintense sulcus was also assessed.Twenty-six (8.9%) of the 291 patients had sulcal hyperintensity (16 focal, 10 diffuse) associated with 18 masses (6.1%) and eight vascular abnormalities (2.7%). Sulcal hyperintensity was frequently associated with the dirty CSF sign (69.2%) and abnormal contrast enhancement (overall, 96.2%; 88.5%, leptomeningeal; 53.8%, vascular enhancement).Our study shows that sulcal hyperintensity on FLAIR imaging can occur in patients without apparent CSF abnormality. Its frequent association with mass effect, vascular disease, abnormal vascular enhancement, and dirty CSF sign suggests that an increase in blood pool, a small amount of protein leakage, and the "flow-entering" phenomenon of the congested blood may contribute to sulcal hyperintensity on FLAIR images.