Perfusion MRI-Based Fractional Tumor Burden Differentiates between Tumor and Treatment Effect in Recurrent Glioblastomas and Informs Clinical Decision-Making.

BACKGROUND AND PURPOSE: Fractional tumor burden better correlates with histologic tumor volume fraction in treated glioblastoma than other perfusion metrics such as relative CBV. We defined fractional tumor burden classes with low and high blood volume to distinguish tumor from treatment effect and to determine whether fractional tumor burden can inform treatment-related decision-making. MATERIALS AND METHODS: Forty-seven patients with high-grade gliomas (primarily glioblastoma) with recurrent contrast-enhancing lesions on DSC-MR imaging were retrospectively evaluated after surgical sampling. Histopathologic examination defined treatment effect versus tumor. Normalized relative CBV thresholds of 1.0 and 1.75 were used to define low, intermediate, and high fractional tumor burden classes in each histopathologically defined group. Performance was assessed with an area under the receiver operating characteristic curve. Consensus agreement among physician raters reporting hypothetic changes in treatment-related decisions based on fractional tumor burden was compared with actual real-time treatment decisions. RESULTS: Mean lower fractional tumor burden, high fractional tumor burden, and relative CBV of the contrast-enhancing volume were significantly different between treatment effect and tumor (P = .002, P < .001, and P < .001), with tumor having significantly higher fractional tumor burden and relative CBV and lower fractional tumor burden. No significance was found with intermediate fractional tumor burden. Performance of the area under the receiver operating characteristic curve was the following: high fractional tumor burden, 0.85; low fractional tumor burden, 0.7; and relative CBV, 0.81. In comparing treatment decisions, there were disagreements in 7% of tumor and 44% of treatment effect cases; in the latter, all disagreements were in cases with scattered atypical cells. CONCLUSIONS: High fractional tumor burden and low fractional tumor burden define fractions of the contrast-enhancing lesion volume with high and low blood volume, respectively, and can differentiate treatment effect from tumor in recurrent glioblastomas. Fractional tumor burden maps can also help to inform clinical decision-making.

Arterial Spin-Labeling Improves Detection of Intracranial Dural Arteriovenous Fistulas with MRI.

BACKGROUND AND PURPOSE: Intracranial dural arteriovenous fistulas carry a risk of substantial neurologic complications but can be difficult to detect on structural MR imaging and TOF-MRA. The purpose of this study was to assess the accuracy and added value of 3D pseudocontinuous arterial spin-labeling MR imaging for the detection of these lesions. MATERIALS AND METHODS: This retrospective study included 39 patients with a dural arteriovenous fistula and 117 controls who had undergone both DSA and MR imaging with pseudocontinuous arterial spin-labeling. Two neuroradiologists blinded to the DSA results independently assessed MR imaging with and without pseudocontinuous arterial spin-labeling. They recorded specific signs, including venous arterial spin-labeling signal, and the likelihood of a dural arteriovenous fistula using a 5-point Likert scale. Logistic regression and receiver operating characteristic analyses were performed to determine the accuracy of specific signs and the added value of pseudocontinuous arterial spin-labeling. Interobserver agreement was determined by using κ statistics. RESULTS: Identification of the venous arterial spin-labeling signal had a high sensitivity (94%) and specificity (88%) for the presence a dural arteriovenous fistula. Receiver operating characteristic analysis showed significant improvement in diagnostic performance with the addition of pseudocontinuous arterial spin-labeling in comparison with structural MR imaging (Δarea under the receiver operating characteristic curve = 0.179) and a trend toward significant improvement in comparison with structural MR imaging with time-of-flight MRA (Δarea under the receiver operating characteristic curve = 0.043). Interobserver agreement for the presence of a dural arteriovenous fistula improved substantially and was almost perfect with the addition of pseudocontinuous arterial spin-labeling (κ = 0.92). CONCLUSIONS: Venous arterial spin-labeling signal has high sensitivity and specificity for the presence of a dural arteriovenous fistula, and the addition of pseudocontinuous arterial spin-labeling increases confidence in the diagnosis of this entity on MR imaging.

The "White Gray Sign" Identifies the Central Sulcus on 3T High-Resolution T1-Weighted Images.

BACKGROUND AND PURPOSE: The central sulcus is an important anatomic landmark, but most methods of identifying it rely on variable gyral and sulcal patterns. We describe and assess the accuracy of reduced gray-white contrast along the central sulcus, an observation we term the "white gray sign." MATERIALS AND METHODS: We conducted a retrospective review of 51 fMRIs with a T1-weighted 3D inversion recovery fast-spoiled gradient-echo and concomitant hand-motor fMRI, which served as confirmation for the location of the central sulcus. To measure gray-white contrast across the central and adjacent sulci, we performed a quantitative analysis of 25 normal hemispheres along the anterior and posterior cortices and intervening white matter of the pre- and postcentral gyri. 3D inversion recovery fast-spoiled gradient-echo axial images from 51 fMRIs were then evaluated by 2 raters for the presence of the white gray sign as well as additional established signs of the central sulcus: the bracket, cortical thickness, omega, and T signs. RESULTS: The mean gray-white contrast along the central sulcus was 0.218 anteriorly and 0.237 posteriorly, compared with 0.320 and 0.295 along the posterior precentral and anterior postcentral sulci, respectively (P < .001). Both raters correctly identified the central sulcus in all 35 normal and 16 abnormal hemispheres. The white gray sign had the highest agreement of all signs between raters and was rated as present the most often among all the signs. CONCLUSIONS: Reduced gray-white contrast around the central sulcus is a reliable sign for identification of the central sulcus on 3D inversion recovery fast-spoiled gradient-echo images.

Non-Relative Value Unit-Generating Activities Represent One-Fifth of Academic Neuroradiologist Productivity.

BACKGROUND AND PURPOSE: A neuroradiologist's activity includes many tasks beyond interpreting relative value unit-generating imaging studies. Our aim was to test a simple method to record and quantify the non-relative value unit-generating clinical activity represented by consults and clinical conferences, including tumor boards. MATERIALS AND METHODS: Four full-time neuroradiologists, working an average of 50% clinical and 50% academic activity, systematically recorded all the non-relative value unit-generating consults and conferences in which they were involved during 3 months by using a simple, Web-based, computer-based application accessible from smartphones, tablets, or computers. The number and type of imaging studies they interpreted during the same period and the associated relative value units were extracted from our billing system. RESULTS: During 3 months, the 4 neuroradiologists working an average of 50% clinical activity interpreted 4241 relative value unit-generating imaging studies, representing 8152 work relative value units. During the same period, they recorded 792 non-relative value unit-generating study reviews as part of consults and conferences (not including reading room consults), representing 19% of the interpreted relative value unit-generating imaging studies. CONCLUSIONS: We propose a simple Web-based smartphone app to record and quantify non-relative value unit-generating activities including consults, clinical conferences, and tumor boards. The quantification of non-relative value unit-generating activities is paramount in this time of a paradigm shift from volume to value. It also represents an important tool for determining staffing levels, which cannot be performed on the basis of relative value unit only, considering the importance of time spent by radiologists on non-relative value unit-generating activities. It may also influence payment models from medical centers to radiology departments or practices.

Diffusion-weighted imaging with dual-echo echo-planar imaging for better sensitivity to acute stroke.

BACKGROUND AND PURPOSE: Parallel imaging facilitates the acquisition of echo-planar images with a reduced TE, enabling the incorporation of an additional image at a later TE. Here we investigated the use of a parallel imaging-enhanced dual-echo EPI sequence to improve lesion conspicuity in diffusion-weighted imaging. MATERIALS AND METHODS: Parallel imaging-enhanced dual-echo DWI data were acquired in 50 consecutive patients suspected of stroke at 1.5T. The dual-echo acquisition included 2 EPI for 1 diffusion-preparation period (echo 1 [TE = 48 ms] and echo 2 [TE = 105 ms]). Three neuroradiologists independently reviewed the 2 echoes by using the routine DWI of our institution as a reference. Images were graded on lesion conspicuity, diagnostic confidence, and image quality. The apparent diffusion coefficient map from echo 1 was used to validate the presence of acute infarction. Relaxivity maps calculated from the 2 echoes were evaluated for potential complementary information. RESULTS: Echo 1 and 2 DWIs were rated as better than the reference DWI. While echo 1 had better image quality overall, echo 2 was unanimously favored over both echo 1 and the reference DWI for its high sensitivity in detecting acute infarcts. CONCLUSIONS: Parallel imaging-enhanced dual-echo diffusion-weighted EPI is a useful method for evaluating lesions with reduced diffusivity. The long TE of echo 2 produced DWIs that exhibited superior lesion conspicuity compared with images acquired at a shorter TE. Echo 1 provided higher SNR ADC maps for specificity to acute infarction. The relaxivity maps may serve to complement information regarding blood products and mineralization.

Diffusion-weighted MRI: distinction of skull base chordoma from chondrosarcoma.

BACKGROUND AND PURPOSE: Chordoma and chondrosarcoma of the skull base are rare tumors with overlapping presentations and anatomic imaging features but different prognoses. We hypothesized that these tumors might be distinguished by using diffusion-weighted MR imaging. MATERIALS AND METHODS: We retrospectively reviewed 19 patients with pathologically confirmed chordoma or chondrosarcoma who underwent both conventional and diffusion-weighted MR imaging. Differences in distributions of ADC were assessed by the Kruskal-Wallis test. Associations between histopathologic diagnosis and conventional MR imaging features (T2 signal intensity, contrast enhancement, and tumor location) were assessed with the Fisher exact test. RESULTS: Chondrosarcoma was associated with the highest mean ADC value (2051 ± 261 × 10(-6) mm(2)/s) and was significantly different from classic chordoma (1474 ± 117 × 10(-6) mm(2)/s) and poorly differentiated chordoma (875 ± 100 × 10(-6) mm(2)/s) (P < .001). Poorly differentiated chordoma was characterized by low T2 signal intensity (P = .001), but other conventional MR imaging features of enhancement and/or lesion location did not reliably distinguish these tumor types. CONCLUSIONS: Diffusion-weighted MR imaging may be useful in assessing clival tumors, particularly in differentiating chordoma from chondrosarcoma. A prospective study of a larger cohort will be required to determine the value of ADC in predicting histopathologic diagnosis.

Clinical evaluation of reduced field-of-view diffusion-weighted imaging of the cervical and thoracic spine and spinal cord.

BACKGROUND AND PURPOSE: DWI has the potential to improve the detection and evaluation of spine and spinal cord pathologies. This study assessed whether a recently described method (rFOV DWI) adds diagnostic value in clinical patients. MATERIALS AND METHODS: Consecutive patients undergoing clinically indicated cervical and/or thoracic spine imaging received standard anatomic sequences supplemented with sagittal rFOV DWI by using a b-value of 500 s/mm(2). Two neuroradiologists blinded to clinical history evaluated the standard anatomic sequences only for pathology and provided their level of confidence in their diagnosis. These readers then rescored the examinations after reviewing the rFOV DWI study and indicated whether this sequence altered findings or confidence levels. RESULTS: Two hundred twenty-three patients were included in this study. One hundred eighty patient scans (80.7%) demonstrated at least 1 pathologic finding. Interobserver agreement for identifying pathology (κ = 0.77) and in assessing the added value of the rFOV DWI sequence (κ = 0.77) was high. In pathologic cases, the rFOV DWI sequence added clinical utility in 33% of cases (P < .00001, Fisher exact test). The rFOV DWI sequence was found to be helpful in the evaluation of acute infarction, demyelination, infection, neoplasm, and intradural and epidural collections (P < .001, χ(2) test) and provided a significant increase in clinical confidence in the evaluation of 11 of the 15 pathologic subtypes assessed (P < .05, 1-sided paired Wilcoxon test). CONCLUSIONS: rFOV diffusion-weighted imaging of the cervical and thoracic spine is feasible in a clinical population and increases clinical confidence in the diagnosis of numerous common spinal pathologies.

Extracranial venous drainage patterns in patients with multiple sclerosis and healthy controls.

BACKGROUND AND PURPOSE: CCSVI hypothesizes an association between impaired extracranial venous drainage and MS. Published sonographic criteria for CCSVI are controversial, and no MR imaging data exist to support the CCSVI hypothesis. Our purpose was to evaluate possible differences in the extracranial venous drainage of MS and healthy controls using both TOF and contrast-enhanced TRICKS MRV. MATERIALS AND METHODS: Healthy subjects (n = 20) and patients with MS (n = 19) underwent axial 2D-TOF neck MRV (to assess flattening) and TRICKS MRV (to assess collaterals) at 3T. Two neuroradiologists blinded to cohort status scored IJV flattening and the severity of non-IJV collaterals by using a 4-point qualitative scale (normal = 0, mild = 1, moderate = 2, severe = 3). κ was used to assess reader agreement. Comparisons between groups were performed by using the Wilcoxon rank sum test. The Spearman rank correlation was used to assess the relationship between IJV flattening and collateral scores and, in patients with MS, EDSS scores. RESULTS: The 2 groups were matched for age and sex (MS, 45 ± 8 years, 79% female; healthy controls, 47 ± 10 years, 65% female). Reader agreement for IJV flattening and collateral severity was good (κ = 0.74) and moderate (κ = 0.58), respectively. While IJV flattening was seen in both patients with MS and healthy controls, scores for the patients with MS were significantly higher (P = .002). Despite a trend, there was no significant difference in collateral scores between groups (P = .063). There was a significant positive correlation between flattening and collateral scores (ρ = 0.32, P = .005) and EDSS and flattening scores (ρ = 0.45, P = .004) but not between EDSS and collateral scores (ρ = 0.01, P = .97). CONCLUSIONS: These results indicate that patients with MS have greater IJV flattening and a trend toward more non-IJV collaterals than healthy subjects. The role that this finding plays in the pathogenesis or progression of MS, if any, requires further study.

Clinical assessment of standard and generalized autocalibrating partially parallel acquisition diffusion imaging: effects of reduction factor and spatial resolution.

BACKGROUND AND PURPOSE: PI improves routine EPI-based DWI by enabling higher spatial resolution and reducing geometric distortion, though it remains unclear which of these is most important. We evaluated the relative contribution of these factors and assessed their ability to increase lesion conspicuity and diagnostic confidence by using a GRAPPA technique. MATERIALS AND METHODS: Four separate DWI scans were obtained at 1.5T in 48 patients with independent variation of in-plane spatial resolution (1.88 mm(2) versus 1.25 mm(2)) and/or reduction factor (R = 1 versus R = 3). A neuroradiologist with access to clinical history and additional imaging sequences provided a reference standard diagnosis for each case. Three blinded neuroradiologists assessed scans for abnormalities and also evaluated multiple imaging-quality metrics by using a 5-point ordinal scale. Logistic regression was used to determine the impact of each factor on subjective image quality and confidence. RESULTS: Reference standard diagnoses in the patient cohort were acute ischemic stroke (n = 30), ischemic stroke with hemorrhagic conversion (n = 4), intraparenchymal hemorrhage (n = 9), or no acute lesion (n = 5). While readers preferred both a higher reduction factor and a higher spatial resolution, the largest effect was due to an increased reduction factor (odds ratio, 47 ± 16). Small lesions were more confidently discriminated from artifacts on R = 3 images. The diagnosis changed in 5 of 48 scans, always toward the reference standard reading and exclusively for posterior fossa lesions. CONCLUSIONS: PI improves DWI primarily by reducing geometric distortion rather than by increasing spatial resolution. This outcome leads to a more accurate and confident diagnosis of small lesions.

Identification of venous signal on arterial spin labeling improves diagnosis of dural arteriovenous fistulas and small arteriovenous malformations.

BACKGROUND AND PURPOSE: DAVFs and small AVMs are difficult to detect on conventional MR imaging/MRA or CTA examinations and often require DSA for definitive diagnosis. The purpose of this study was to assess the value of venous signal intensity on ASL imaging for making this diagnosis. MATERIALS AND METHODS: Two neuroradiologists and 1 neurologist reviewed MR imaging studies in 26 patients, 15 of whom had DSA-proved DAVFs or small (<2 cm) AVMs. Pseudocontinuous ASL was performed at 1.5T with background-suppressed 3D-FSE readout. Using a 5-point scale, these readers assessed the likelihood of positive findings on a DSA study before and after reviewing the ASL findings. Agreement on imaging findings, including venous ASL signal intensity, was performed by using κ statistics. Logistic regression and ROC analysis were performed to determine which imaging findings improved diagnosis. RESULTS: Venous ASL signal intensity was seen frequently in cases with positive findings on DSA. The sensitivity and specificity of venous ASL signal intensity for predicting positive findings on a DSA study were 78% and 85%, respectively. On ROC analysis, there was a significant increase in the AUC after review of the ASL images (AUC = 0.798 pre-ASL, AUC = 0.891 post-ASL; P = .02). Multivariate regression identified venous ASL signal intensity as the strongest predictor of positive findings on a DSA study, with an odds ratio of 17.3 (95% CI, 3.3-90.4). CONCLUSIONS: Identifying venous ASL signal intensity improved detection of DAVFs and small AVMs. Attention to this finding may improve triage to DSA in patients with suspected small vascular malformations.

Comparison of MR and contrast venography of the cervical venous system in multiple sclerosis.

BACKGROUND AND PURPOSE: MRV has been proposed as a possible screening method to identify chronic cerebrospinal venous insufficiency, which may play a role in MS. We report our initial experience comparing MRV and CV in MS patients to evaluate venous stenosis and collateral venous drainage. MATERIALS AND METHODS: Time-of-flight and time-resolved imaging of contrast kinetics MRV and CV were performed in 39 MS patients. The presence and severity of both IJ vein caliber changes and non-IJ collaterals were graded by using a 4-point scale by 2 radiologists in an independent and blinded manner. RESULTS: Both studies frequently showed venous abnormalities, most commonly IJ flattening at the C1 level and in the lower neck. There was moderate-to-good agreement between the modalities (κ = 0.55; 95% CI, 0.45%-0.65%). For collaterals, agreement was only fair (κ = 0.30; 95% CI, 0.09%-0.50%). The prevalence of IJ segments graded mild or worse on CV was 54%. If CV was considered a standard, the sensitivity and specificity of MRV was 0.79 (0.71-0.86) and 0.76 (0.67-0.83), respectively. Degree of stenosis was related to the severity of collaterals for CV but not for MRV. CONCLUSIONS: IJ caliber changes were seen in characteristic locations on both MRV and CV in MS patients. Agreement between modalities was higher for stenosis than for collaterals. If CV is considered a standard, MRV performance is good but may require additional improvement before MRV can be used for screening.

Reduced field-of-view diffusion imaging of the human spinal cord: comparison with conventional single-shot echo-planar imaging.

BACKGROUND AND PURPOSE: DWI of the spinal cord is challenging because of its small size and artifacts associated with the most commonly used clinical imaging method, SS-EPI. We evaluated the performance of rFOV spinal cord DWI and compared it with the routine fFOV SS-EPI in a clinical population. MATERIALS AND METHODS: Thirty-six clinical patients underwent 1.5T MR imaging examination that included rFOV SS-EPI DWI of the cervical spinal cord as well as 2 comparison diffusion sequences: fFOV SS-EPI DWI normalized for either image readout time (low-resolution fFOV) or spatial resolution (high-resolution fFOV). ADC maps were created and compared between the methods by using single-factor analysis of variance. Two neuroradiologists blinded to sequence type rated the 3 DWI methods, based on susceptibility artifacts, perceived spatial resolution, signal intensity-to-noise ratio, anatomic detail, and clinical utility. RESULTS: ADC values for the rFOV and both fFOV sequences were not statistically different (rFOV: 1.01 ± 0.18 × 10(-3) mm(2)/s; low-resolution fFOV: 1.12 ± 0.22 × 10(-3) mm(2)/s; high-resolution fFOV: 1.10 ± 0.21 × 10(-3) mm(2)/s; F = 2.747, P > .05). The neuroradiologist reviewers rated the rFOV diffusion images superior in terms of all assessed measures (P < 0.0001). Particular improvements were noted in patients with metal hardware, degenerative disease, or both. CONCLUSIONS: rFOV DWI of the spinal cord overcomes many of the problems associated with conventional fFOV SS-EPI and is feasible in a clinical population. From a clinical standpoint, images were deemed superior to those created by using standard fFOV methods.

CT angiography as a screening tool for dural arteriovenous fistula in patients with pulsatile tinnitus: feasibility and test characteristics.

BACKGROUND AND PURPOSE: The diagnosis of intracranial DAVF with noninvasive cross-sectional imaging such as CTA is challenging. We sought to determine the sensitivity and specificity of CTA compared with cerebral angiography for DAVF in patients presenting with PT. MATERIALS AND METHODS: Following approval of the institutional review board, we reviewed all patients who underwent CTA for PT from 2004 to 2009 and collected clinical and imaging data. Seven patients with PT and proved DAVF and 7 age- and sex-matched control patients with PT but no DAVF composed the study group. CTA images were blindly interpreted by 2 experienced neuroradiologists for the presence of 5 variables: asymmetric arterial feeding vessels, "shaggy" appearance of a dural venous sinus, transcalvarial venous channels, asymmetric venous collaterals, and abnormal size and number of cortical veins. Asymmetric attenuation of jugular veins was additionally assessed. RESULTS: The presence of arterial feeders showed good test characteristics for screening, with a sensitivity of 86% (95% CI, 42-99) and a specificity of 100% (95% CI, 52-100). A shaggy sinus or tentorium was highly specific: sensitivity of 42% (95% CI, 11-79) and specificity of 100% (95% CI, 56-100). The presence of transcalvarial venous channels demonstrated a poor sensitivity of 29% (95% CI, 5-70) but a high specificity 86% (95% CI, 42-99). CT attenuation of the jugular veins showed statistically significant asymmetry in the DAVF group versus the control group (P < .05). CONCLUSIONS: CTA can be used to screen for DAVF in patients with PT. The presence of asymmetrically visible and enlarged arterial feeding vessels has a high sensitivity and specificity for the diagnosis of DAVF.

Association of venous malformation of the head and neck with meningoencephalocele: report of 3 cases.

Venous malformations have previously been reported to be associated with skeletal changes in humans, typically demineralization and localized deformation of the long bones. We report a presumed developmental association between venous malformations of the head and neck and meningoencephaloceles involving the sphenoid and temporal bones. Recognition of this association is important to avoid misinterpretation of these changes as a more aggressive process. We present the imaging findings and suggest an embryologic basis for this previously unreported association.

Retrosellar intracranial extracerebral glioneuronal heterotopion: case report.

We report the case of an 18-year-old woman with an intradural retroclival retrosellar glioneuronal heterotopion. At the time of surgery, a well circumscribed pale-tan mass was identified posterior to and distinct from the posterior pituitary. Pathologic examination showed disorganized, non-neoplastic glial tissue characteristic of glioneuronal heterotopia. To our knowledge, this is the first report of such a lesion in this location.

Unilateral calcification of the caudate and putamen: association with underlying developmental venous anomaly.

Stenosis of a DVA may result in chronic venous ischemia. We present 6 patients (3 men, 3 women; age range, 30-79 years; mean age, 53 years) with unilateral calcification of the caudate and putamen on noncontrast CT. This calcification typically spared the anterior limb of the internal capsule. No patient presented with symptoms referable to the basal ganglia or had an underlying metabolic disorder or other process associated with calcium deposition. All patients subsequently underwent gadolinium-enhanced MR imaging and/or CTA or conventional angiography demonstrating the presence of an adjacent DVA. We hypothesize that chronic venous ischemia in the drainage territory of the DVA causes the abnormal mineralization. Greater recognition of this entity will prevent misinterpretation of this finding as acute hemorrhage and will prevent unnecessary and sometimes invasive evaluation in such patients. Furthermore, this entity should be considered in the differential diagnosis of unilateral basal ganglia hyperattenuation.

Artery of percheron infarction: imaging patterns and clinical spectrum.

BACKGROUND AND PURPOSE: Occlusion of the AOP results in a characteristic pattern of ischemia: bilateral paramedian thalamus with or without midbrain involvement. Although the classic imaging findings are often recognized, only a few small case series and isolated cases of AOP infarction have been reported. The purpose of this study was to characterize the complete imaging spectrum of AOP infarction on the basis of a large series of cases obtained from multiple institutions. MATERIALS AND METHODS: Imaging and clinical data of 37 patients with AOP infarction from 2000 to 2009 were reviewed retrospectively. The primary imaging criterion for inclusion was an abnormal signal intensity on MR imaging and/or hypoattenuation on CT involving distinct arterial zones of the bilateral paramedian thalami with or without rostral midbrain involvement. Patients were excluded if there was a neoplastic, infectious, or inflammatory etiology. RESULTS: We identified 4 ischemic patterns of AOP infarction: 1) bilateral paramedian thalamic with midbrain (43%), 2) bilateral paramedian thalamic without midbrain (38%), 3) bilateral paramedian thalamic with anterior thalamus and midbrain (14%), and 4) bilateral paramedian thalamic with anterior thalamus without midbrain (5%). A previously unreported finding (the "V" sign) on FLAIR and DWI sequences was identified in 67% of cases of AOP infarction with midbrain involvement and supports the diagnosis when present. CONCLUSIONS: The 4 distinct patterns of ischemia identified in our large case series, along with the midbrain V sign, should improve recognition of AOP infarction and assist with the neurologic evaluation and management of patients with thalamic strokes.

Salivary gland anlage tumor in a neonate presenting with respiratory distress: radiographic and pathologic correlation.

We present a case of congenital salivary gland anlage tumor (SGAT) of the nasal septum in a 2-week-old infant who had difficulty breathing through her nose since birth. CT and MR imaging demonstrated a circumscribed mass within the nasal cavity that did not communicate with the intracranial compartment. Differential diagnosis and clinical significance of recognizing this rare lesion are reviewed.

Comparison of multidetector CT angiography and MR imaging of cervical artery dissection.

BACKGROUND AND PURPOSE: Conventional angiography has been historically considered the gold standard for the diagnosis of cervical artery dissection, but MR imaging/MR angiography (MRA) and CT/CT angiography (CTA) are commonly used noninvasive alternatives. The goal of this study was to compare the ability of multidetector CT/CTA and MR imaging/MRA to detect common imaging findings of dissection. MATERIALS AND METHODS: Patients in the data base of our Stroke Center between 2003 and 2007 with dissections who had CT/CTA and MR imaging/MRA on initial work-up were reviewed retrospectively. Two neuroradiologists evaluated the images for associated findings of dissection, including acute ischemic stroke, luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap. The readers also subjectively rated each vessel on the basis of whether the imaging findings were more clearly displayed with CT/CTA or MR imaging/MRA or were equally apparent. RESULTS: Eighteen patients with 25 dissected vessels (15 internal carotid arteries [ICA] and 10 vertebral arteries [VA]) met the inclusion criteria. CT/CTA identified more intimal flaps, pseudoaneurysms, and high-grade stenoses than MR imaging/MRA. CT/CTA was preferred for diagnosis in 13 vessels (5 ICA, 8 VA), whereas MR imaging/MRA was preferred in 1 vessel (ICA). The 2 techniques were deemed equal in the remaining 11 vessels (9 ICA, 2 VA). A significant preference for CT/CTA was noted for VA dissections (P < .05), but not for ICA dissections. CONCLUSION: Multidetector CT/CTA visualized more features of cervical artery dissection than MR imaging/MRA. CT/CTA was subjectively favored for vertebral dissection, whereas there was no technique preference for ICA dissection. In many cases, MR imaging/MRA provided complementary or confirmatory information, particularly given its better depiction of ischemic complications.

Focal opacification of the olfactory recess on sinus CT: just an incidental finding?

BACKGROUND AND PURPOSE: The CT appearance of the anterior skull base has been investigated but with limited attention directed to the olfactory recess. As defined by opacity abutting the undersurface of the cribriform plate, the prevalence of olfactory recess opacity (ORO) on sinus CT was examined to clarify whether this should raise suspicion for an unsuspected pathologic process. MATERIALS AND METHODS: Outpatient sinus CTs were evaluated for ORO in 500 consecutive patients (mean age, 46.9 years; 52.6% women). On a per-side basis (n = 1000), the presence of surgical changes, inflammatory sinus disease, and concha bullosa was determined by 2 neuroradiologists. Logistic regression was used to examine the association of ORO with these variables. RESULTS: ORO was identified in 59 (11.8%) patients, bilateral in 27 (5.4%), and unilateral in 32 (6.4%). There were 343 of 1000 ethmoid sides that were diseased, and 66 (27.2%) showed ipsilateral ORO. In contrast, only 20 (3.0%) of 657 clear ethmoid sides showed ORO (P < .0001). ORO was significantly (P = .013) more common with previous surgery (18/75; 24.0%) than without (68/925; 7.4%). Ipsilateral concha bullosa was not associated with ORO. Of 32 patients with unilateral ORO, 5 (15.6%) had no ethmoid opacification or previous surgery, and 1 of these patients had an encephalocele causing the ORO. Finally, unilateral ORO was present in only 1 of 122 patients with completely clear sinuses (the encephalocele that was just mentioned). CONCLUSION: ORO is distinctly uncommon without sinonasal inflammation or previous surgery. Isolated unilateral ORO raises suspicion for an underlying neoplasm or cephalocele and warrants further evaluation.