The “dural tail” adjacent to meningiomas studied by dynamic contrast-enhanced MRI: a comparison with histopathology

We examined 32 patients with intracranial tumors (17 meningiomas, 8 neuromas, 7 pituitary adenomas) by conventional and dynamic contrast-enhanced MRI. Our aim was to clarify whether the pathological dural contrast enhancement adjacent to meningiomas (the dural tail) is specific to meningiomas and, more important, whether it represents neoplastic dural infiltration or hypervascularization as a tumor accompanying reaction. A dural tail was found in 9 of 17 meningiomas. None of the other extra-axial tumours (neuromas, pituitary adenomas) showed comparable dural enhancement. Dynamic examinations with an ultrafast single slice imaging technique (snapshot-FLASH) after a bolus injection of contrast medium showed a dural tail in seven out of these nine meningiomas, while in two cases the dural tail turned out to be a cortical vein with a characteristic dynamic contrast enhancement pattern. In the dynamic study all seven dural tails were found to have earlier, steeper contrast enhancement than the corresponding tumours. All the tumours and part of the adjacent dura mater in four of the seven meningiomas with dural enhancement were examined histopathologically. In none of these four cases was neoplastic tissue found more than 2 mm away from the main tumour. The results strongly support the suggestion that the dural tail adjacent to meningiomas represents a hypervascular, non-neoplastic dural reaction.     

Myxofibrosarcoma: prevalence and diagnostic value of the “tail sign” on magnetic resonance imaging

Objective

Myxofibrosarcoma frequently shows curvilinear extensions of high T2 signal that also enhance on magnetic resonance imaging; these “tails” represent fascial extension of tumor at histopathological examination. This study was performed to determine whether the tail sign is helpful in distinguishing myxofibrosarcoma from other myxoid-containing neoplasms.

Materials and methods

The study group consisted of 44 patients with pathologically proven myxofibrosarcoma; the control group consisted of 52 patients with a variety of other myxoid-predominant tumors. Three musculoskeletal radiologists independently evaluated T2-weighted (and/or short-tau inversion recovery) and post-contrast MR images for the presence of one or more enhancing, high-signal intensity, curvilinear projections from the primary mass. Sensitivity and specificity for the diagnosis of myxofibrosarcoma were calculated for each reader. Interobserver variability was assessed with kappa statistic and percentage agreement.

Results

A tail sign was deemed present in 28, 30, and 34 cases of myxofibrosarcoma and in 11, 9, and 5 of the controls for the three readers respectively, yielding a sensitivity of 64–77 % and a specificity of 79–90 %. The interobserver agreement was moderate-to-substantial (kappa?=?0.626).

Conclusion

The tail sign at MRI is a moderately specific and sensitive sign for the diagnosis of myxofibrosarcoma relative to other myxoid-containing tumors.     

Dynamic nature of the CT angiographic “spot sign”

The “spot sign”, first described in 2007, has shown that a focal area of contrast extravasation within an intracerebral haematoma (ICH) can be correlated with haematoma expansion. We describe a case where time-resolved dynamic CT angiography (dCTA) shows the appearance of the “spot sign” only in later images. This finding highlights the importance of timing of the static CT angiogram which, if performed too early, might result in a false-negative diagnosis.Contrast extravasation into an intracerebral haemorrhage has been associated with haematoma growth and poor clinical outcomes including death [1, 2]. More recently, the “spot sign” has been validated as a marker of intracerebral haematoma (ICH) expansion [3]. However, these imaging studies are static, acquired at a particular point in time. Dynamic CT angiography (dCTA) demonstrates temporal wash-in and wash-out of intravenous contrast material over a chosen temporal resolution. This allows temporal visualisation of contrast flowing through vessels. We present a case capturing distinct areas of “spot sign” within an acute ICH using time-resolved dCTA.The success of future therapies, including haemostatic agents, for the treatment of ICH may depend on accurate determination of haematomas at risk of expansion [4].     

Value of the “spine sign” on lateral chest views

Objective:

To determine the performance of the spine sign in detecting lower chest abnormalities in the lateral view.

Methods:

This retrospective study included 200 patients who had undergone lateral view and CT scans of the chest within 1 week. Two radiologists independently read the lateral views, and a third radiologist, blinded to the aim of the study, read the scans. The spine sign was considered as positive if the progressive increase in lucency of the vertebral bodies was altered. Interreader agreement was calculated through k-statistics. Sensitivity, specificity, positive- and negative-predictive values, and accuracy were calculated compared with CT.

Results:

Agreements between readers ranged from 0.12 to 0.68. Positive spine sign could appear in two ways: absent or inversed progressive increase in lucency of the vertebral bodies. Sensitivity, specificity, positive- and negative-predictive values, and accuracy were, respectively, 60% and 70%; 64% and 84%; 91% and 97%; 19% and 29%; and 61% and 72% for each reader (p-value ranging from 0.026 to 0.196). Abnormalities most frequently associated with positive spine sign were plate-like atelectasis, ground-glass opacity, pleural effusion and consolidation.

Conclusion:

The spine sign can present as an absent or inversed progressive increase in lucency of the vertebral bodies. It has a moderate sensitivity but a good positive-predictive value, so it can be useful especially when it appears as inversed progressive increase in lucency of the vertebral bodies to detect various abnormalities usually identifiable on chest radiographs.

Advances in knowledge:

On lateral chest radiographs, the spine sign is useful to detect lower chest abnormalities and is related to various underlying abnormalities and is, per se, non-specific.On lateral chest view obtained in normal subjects, the overall posterior opacity tends to decrease from the level of the upper thoracic spine to that of the diaphragm.^1,2 The “spine sign” is any alteration in this typical pattern and is suggestive of pathology in the lower part of the chest.³ While commonly used, the diagnostic performance of this sign for detecting lower lobe abnormalities remains unknown. The aims of our study were therefore to determine its sensitivity, specificity, positive- and negative-predictive values; to determine the accuracy of the spine sign compared with CT as a method of reference; and to characterize its associated lesions.     

Trapped on the “whirl”: diagnostic sign on emergency CT

The “whirl sign” is an uncommon finding on emergency CT. However, it is easy to overlook if not kept in mind. Its recognition is of capital importance, being most of its causes potentially lethal. Surgical treatment is also mandatory when signs of complication are found. The whirl sign is usually found associated to midgut, cecal and sigmoid volvulus, small-bowel volvulus and closed-loop obstructions, and post-surgical mesenteric windows (including retroanastomotic hernias). CT is an optimal imaging technique to depict the so-called sign and associated CT features suggesting complication (circumferential wall thickening, pneumatosis intestinalis, pneumoperitoneum, mesenteric fat stranding, free intraperitoneal fluid, mesenteric haziness). Radiologists must be able to recognize the whirl sign and seek associated findings that strongly support the diagnosis of a spectrum of entities, some of them lethal if no treatment is established.     

Acute appendicitis: the false-positive observations prospective diagnosis — value of the “rod” sign

Three hundred and ninety patients with an equivocal clinical diagnosis of acute appendicitis were evaluated using graded compression sonography. In 9 of 28 patients with visualised normal appendices (based on a maximal outer diameter criterion 6 mm or less) and in 11 of 23 false-positive cases sonography revealed a striking pattern consisting of a relatively homogeneous non-shadowing thick ( > 1.5 mm) central hyperechoic zone coupled with normal wall thickness (< 3.0 mm). Postappendectomy histological correlations obtained in 2 cases from the former group and in 3 cases from the latter one revealed only the presence of chronic coprostasis with no signs of acute inflammation. It is suggested that the appendiceal part displaying the rod sign is indicative of dilated faeces-filled lumen (the faecal contents being in some degree inspissated, however, not yet appendicoliths) and it may be classified as normal even if its outer diameter is greater than 6 mm. Correspondence to: V. imonovský     

“Sukeroku sign” and “dent internal-capsule sign”—identification guide for targeting the subthalamic nucleus for placement of deep brain stimulation electrodes

Introduction  The purpose of this study was to assess the usefulness of signs (“Sukeroku sign” and “dent internal-capsule sign”) for the recognition of subthalamic nucleus (STN). Materials and methods  Five Parkinson’s disease cases in which there was a successful placement of deep brain stimulation (DBS) electrodes at the STN were retrospectively reviewed. Five radiologists who were not engaged in localization of STNs in clinical practice were asked to locate the STNs before and after instructions on the signs. We evaluated the deviation between the reader-located points and the location of the DBS electrode for which there had been a successful installation. Results  After instruction, there was a significant reduction in the deviation between the reader-located points and the DBS electrode. The time required for localization was also reduced after the instructions. Conclusion  Sukeroku sign and dent internal-capsule sign are feasible indicators of STN and seem to be useful in helping to identify the STN.     

CT and MR imaging of the “target sign” in metastatic brain disease

The “target sign” is a common finding in granulomatous infection. A case with the target sign in metastatic brain tumor from small cell lung carcinoma is reported. Received: 28 September 1998; Revised: 15 March 1999; Accepted: 15 April 1999     

Remission of “mistletoe sign” after treatment

We described a 55-year-old man, in whom the first manifestation of retroperitoneal fibrosis (RPF) was only coronary arterial involvement, which had no periaortic or peri-iliac and urinary system retroperitoneum involvement in general and other systemic clinical manifestations. Coronary manifestation was called “mistletoe sign” on the images. Here, we report a case of IgG4-related RPF remission that was only coronary arterial involvement after treatment.     

Renal angiomyolipoma with inferior vena caval extension: MRI demonstration of a “thread-and-streaks” sign

The MR findings in a case of tumor extension into an inferior vena cava from a right renal angiomyolipoma are reported. The flow void demonstrated within the intracaval tumor thrombus on T1-weighted images was consistent with the so-called thread-and-streaks sign. Correspondence to: K. Matsuura     

The “pool sign” of metastatic adenocarcinoma

The differential of a newly discovered solitary intracranial mass is a primary intracranial neoplasm and metastatic disease. Differentiating between the two entities on imaging is difficult, though there are clues on conventional imaging that suggest one over the other. The purpose of this article is to describe a new imaging finding on T2-weighted imaging, the “pool sign,” that may be specific for metastatic adenocarcinomas and can help differentiate a solitary metastasis from a primary CNS neoplasm. We present a series of four patients with initial magnetic resonance imaging of a solitary intracranial mass demonstrating the “pool sign,” and therefore predicted to be metastatic adenocarcinoma. All of these cases were confirmed to be metastatic adenocarcinoma on pathology.     

Internal hernia through the foramen of Winslow: the “narrowed portal vein” sign on abdominal CT

We report a case of ileal internal hernia through the foramen of Winslow into the lesser sac. Preoperative computed tomography (CT) demonstrated that the herniated ileum, which showed a closed-loop obstruction, was located behind the portal vein, and the vein was subsequently compressed and narrowed by the herniated ileum. We found that similar cases in the literature of Winslow’s foramen hernias that caused portal vein compression; however, portal vein narrowing has not been described as a characteristic CT finding. The narrowed portal vein sign could be useful in diagnosing the hernia through the foramen of Winslow.     

Risser sign inter-rater and intra-rater agreement: is the Risser sign reliable?

Background  Studies directly evaluating the reliability of the Risser sign are few in number, possess small sample sizes, and offer conflicting results. This study establishes the reliability of the Risser sign on a large sample size in an effort to provide clarification on the subject. Methods  Two years’ worth of AP pelvis radiographs from patients age 8–20 were downloaded from our institution’s digital imaging system. One hundred of these images were selected for inclusion by an independent reviewer whose goal was to capture a spread of radiographs that included all Risser stages. Risser grading occurred in two rounds. In each round, three examiners randomly reviewed the 100 radiographs on three different occasions. The full AP pelvis radiograph was graded in Round 1 while only the iliac apophysis was visible in Round 2. Kappa coefficients and their confidence bounds are reported to indicate intra- and inter-observer reliability. The contrast between the rates of agreement about Risser stages in Rounds 1 versus 2 was assessed by McNemar’s test. The signed-rank test was used to evaluate differences in intra-observer values between rounds. Results  Round 1 inter-observer kappa was 0.76. Round 2 inter-observer kappa was 0.51. In Round 1, 63 radiographs showed perfect agreement within the same Risser stage for all observations compared to 44 radiographs with perfect agreement within the same Risser stage in Round 2 (p = 0.004). Round 1 intra-observer kappa values were 0.92, 0.86, and 0.88. Round 2 intra-observer kappa values were 0.91, 0.77, and 0.88. Intra-observer value differences between rounds were not significant for two observers (p = 0.074, 0.061) but was significant for the third observer (p = 0.002). Conclusion  The reliability of the Risser sign is acceptable and can be further improved when other markers of skeletal maturity on the pelvis radiograph are used to assist in grading. The Chief, Bureau of Medicine and Surgery, Navy Department, Washington, D.C., Clinical Investigation Program, sponsored this report # 05-039 as required by NSHSBETHINST 6000.41B. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government. Key points:1. The inter-observer agreement of the Risser sign is substantial. 2. The intra-observer agreement of the Risser sign is almost perfect.3. The reliability of the Risser sign can be improved when other markers of skeletal maturity on the pelvis radiograph are used to assist in grading.     

Osteoid osteoma—the CT vessel sign

Objective  

To evaluate whether the presence of a feeding vessel in proximity to osteoid osteomas of long bones on multidetector CT (MDCT) can be an adjuvant clue for the diagnosis of osteoid osteoma.     

The “sliver sign”: a specific radiographic sign of acute lateral patellar dislocation

Objective  

The objective of this work is to assess the prevalence of the sliver sign, defined as an intraarticular linear or curvilinear ossific density, in association with knee effusion in patients with acute knee trauma, as a predictor of recent lateral patellar dislocation (LPD).     

Computed tomography appearance of golden's “S” sign

The computed tomography version of Golden's “S” sign is strongly suggestive of a centrally obstructing carcinoma. Although more easily seen in the right lung, the “S” sign can be detected in any lobe on computed tomography. The computed tomography appearance of Golden's “S” sign is described and illustrated.     

The “botryoid sign”: a characteristic feature of rhabdomyosarcomas in the head and neck

We investigated nine patients with rhabomyosarcoma in the head and neck (6–53 years of age), using CT and MRI. The tumours originated in the paranasal sinuses (3), cheek (2), soft palate (1), orbit (1), sternocostoclavicular muscle (1) and parapharyngeal space (1). The histological subtype was embryonal in five, alveolar in three and pleomorphic in one case. The tumours enhanced markedly and heterogeneous on CT and MRI. The masses were isointense or gave slightly higher signal than surrounding muscles on T1- and heterogeneously high signal on T2-weighted images. In four tumours, multiple ring enhancement resembling bunches of grapes. This appears to be characteristic of rhabdomyosarcoma and probably reflects a component of botryoid-type rhabdomyosarcoma in which mucoid-rich stroma is covered with a thin layer of tumour cells. We have named this imaging feature the “botryoid sign”. Received: 9 March 2000 Accepted: 12 July 2000