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     

The “ivy sign score” on FLAIR MR images: Clinical utility following revascularization in pediatric Moyamoya disease

Purpose

The aim was to evaluate post-operative changes in the Ivy sign on unenhanced fluid-attenuated inversion-recovery (FLAIR) following surgical intervention in pediatric Moyamoya disease (MMD) and assess its clinical utility as an indicator of hemodynamic improvement.

Renal cysts: is attenuation artifactually increased on contrast-enhanced CT images?

PURPOSE: To determine if the attenuation values of simple renal cysts are artifactually increased on contrast material-enhanced, clinically acquired spiral computed tomographic (CT) images. MATERIALS AND METHODS: Dual-phase renal spiral CT studies (5-mm collimation; pitch, 1.0) were retrospectively analyzed in 24 consecutive patients who had ultrasonographic (US) documentation of simple renal cysts. Forty-eight cysts were identified. The attenuation values of each cyst were measured on nonenhanced, cortical phase, and nephrographic phase images. The size and the location of each cyst in relation to the renal parenchyma were also recorded. RESULTS: The cysts were 0.6-10.8 cm in diameter (mean, 2.6 cm; SD, 2.0). The mean attenuation change in the cysts from nonenhanced to contrast-enhanced images was statistically significant in a comparison of cortical phase and nephrographic phase images (P: <.01): +1.8 HU (SD, 3.8) for cortical phase and +3. 6 HU (SD, 5.6) for nephrographic phase images. Renal cysts 1.0 cm or smaller showed a higher attenuation increase (mean, +4.0 HU for cortical phase and +11.0 HU for nephrographic phase). None of the renal cysts larger than 1.0 cm demonstrated an increase greater than 10 HU (mean, +1.4 HU for cortical phase and +2.3 HU for nephrographic phase). Intraparenchymal cysts showed higher mean attenuation changes than the exophytic cysts. CONCLUSION: Attenuation values in the renal cysts increased artifactually on contrast-enhanced images, but this pseudoenhancement was not substantial and was less than 10 HU when the cyst was larger than 1. 0 cm in diameter.     

Hooking intestine sign: a typical diagnostic CT finding of Petersen’s hernia

Purpose

To clarify typical diagnostic computed tomography (CT) findings of Petersen’s hernia for differentiation from other causes of internal hernia observed in patients having undergone gastrectomy with Roux-en-Y gastric bypass.

Methods

We retrospectively reviewed CT findings of internal hernia in patients who had undergone both gastrectomy and Roux-en-Y reconstruction and a second surgery for bowel obstruction. Thirteen patients with Petersen’s hernia and 6 with internal hernia other than Petersen’s hernia were investigated. Six CT findings, viz. whirl sign, mesenteric fat haziness, intestinal distension in the upper abdomen, herniated intestinal loop above the gastric level, middle/distal ileum courses downwards from the left hypochondrium, and hooking intestine sign, which means two or more intestines pass through the inner side of J-shaped vessels consisting of mesenteric vessels of the elevated jejunum, were scored and evaluated regarding their diagnostic performance.

Results

The hooking intestine sign showed the highest sensitivity, specificity and accuracy (100%, 100% and 100%). We could detect J-shaped vessels in all Petersen’s hernia patients. Inside the J-shaped vessels there were two or more intestinal tracts passing through in the Petersen’s hernia group. There was only transverse colon inside the J-shaped vessels in the control group.

Conclusion

The hooking intestine sign may be useful for diagnosing Petersen’s hernia on CT.

     

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.     

Acquisition of MR perfusion images and contrast-enhanced MR angiography in acute ischaemic stroke patients: which procedure should be done first?

Multimodal MRI for acute ischaemic stroke usually includes perfusion imaging (PI) and contrast-enhanced neck MR angiography (CE-MRA), as well as diffusion-weighted imaging and T2* weighted imaging. Because both PI and CE-MRA require the infusion of contrast medium, the likelihood exists that one study may conflict with the other due to the accumulation of previously injected contrast medium. The purpose of this study is to determine the appropriate order of PI and CE-MRA in this multimodal MRI protocol for evaluation of acute ischaemic stroke. We studied 35 patients with acute ischaemic stroke in the unilateral middle cerebral artery territory. 17 patients underwent CE-MRA following PI (group A) and 18 patients underwent PI following CE-MRA (group B). For qualitative analysis of the CE-MRA and colour-coded maps of the PI, two independent observers graded the image quality. Interobserver agreement was assessed using kappa statistics, and we assessed the statistical differences of imaging quality between groups A and B using the Mann-Whitney U-test). For the quantitative analysis of PI, two parameters--the maximum change in the transverse relaxation rate (DeltaR2(max)) and the relative signal drop (DeltaS/S(0))--were calculated from the time-signal intensity curve of an unaffected middle cerebral artery territory, and we compared the differences in the parameters of group A and B (t-test). Interobserver agreements for CE-MRA and PI were good. In the qualitative analysis of CE-MRA and PI, no significant difference was observed between groups A and B. In the quantitative analysis of PI, there were no relevant differences in DeltaR2(max) and DeltaS/S(0) between the two groups. In simultaneous CE-MRA and PI, there was no deterioration of diagnostic imaging quality with regard to the order of the two post-contrast sequences. They can be performed according to the preference of each institution.     

“Tenomalacia”: a new sonographic sign of tendinopathy?

The purpose of this study was to assess tendon compressibility with sonography in extensor tendinopathy and in asymptomatic extensor tendons of the elbow. Sonography of both elbows was performed in eight patients with a clinical diagnosis of unilateral lateral epicondylitis. Tendons were assessed for compressibility by measuring their thickness before and after compression with the transducer. The same manoeuvre was performed while tendon vascularity was assessed with colour Doppler. All eight cases showed increased compressibility of the common extensor tendon on the painful side compared to the asymptomatic side, as well as increased vascularity with compressible vessels on colour Doppler. Other signs of tendinopathy were hypoechogenicity (n = 8), loss of fibrillar pattern (n = 8), intratendinous calcifications (n = 1), partial tears (n = 3), and enthesophytes (n = 5). Increased tendon compressibility indicative of tendon softening or “tenomalacia” is a new sonographic sign of common extensor tendinopathy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

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).     

Time-of-flight angiography: a viable alternative to contrast-enhanced MR angiography and fat-suppressed T1w images for the diagnosis of cervical artery dissection?

Objectives

To compare the use of an unenhanced high-resolution time-of-flight MR angiography sequence (Hr-TOF MRA) with fat-suppressed axial/coronal T1-weighted images and contrast-enhanced angiography (standard MRI) for the diagnosis of cervical artery dissection (cDISS).

Methods

Twenty consecutive patients (9 women, 11 men, aged 24–66 years) with proven cDISS on standard MRI underwent Hr-TOF MRA at 3.0 T using dedicated surface coils. Sensitivity (SE), specificity (SP), positive and negative predictive values (PPV, NPV), Cohen’s kappa (к) and accuracy of Hr-TOF MRA were calculated using the standard protocol as the gold standard. Image quality and diagnostic confidence were assessed on a four-point scale.

Results

Image quality was rated better for standard MRI (P?=?0.02), whereas diagnostic confidence did not differ significantly (P?=?0.27). There was good agreement between Hr-TOF images and the standard protocol for the presence/absence of cDISS, with к?=?0.95 for reader 1 and к?=?0.89 for reader 2 (P?<?0.001). This resulted in SE, SP, PPV, NPV and accuracy of 97 %, 98 %, 97 %, 98 % and 97 % for reader 1 and 93 %, 96 %, 93 %, 96 % and 95 % for reader 2.

Conclusions

Hr-TOF MRA can be used to diagnose cDISS with excellent agreement compared with the standard protocol. This might be useful in patients with renal insufficiency or if contrast-enhanced MR angiography is of insufficient image quality.

Key Points

? New magnetic resonance angiography sequences are increasingly used for vertebral artery assessment. ? A high-resolution time-of-flight sequence allows the diagnosis of cervical artery dissection. ? This technique allows the diagnosis without intravenous contrast medium. ? It could help in renal insufficiency or when contrast-enhanced MRA fails.     

Is “black geode” sign a characteristic MRI finding for extracranial schwannomas?

Purpose:

To evaluate whether the “black geode” sign is a characteristic magnetic resonance imaging (MRI) finding for extracranial schwannomas.

Materials and Methods:

Forty‐three patients with pathologically confirmed extracranial schwannomas underwent preoperative gadolinium‐enhanced MRI. The black geode sign was defined as the appearance of enhanced outer and inner rings. MR images were retrospectively reviewed for size, configuration, and signal intensity of the lesions in addition to the presence of the black geode sign.

Results:

Gadolinium‐enhanced T1‐weighted images revealed the black geode sign in seven of 43 patients (16%). The thickness of inner rings (mean 0.6 cm, range 0.3–0.8 cm) was significantly greater than that of outer rings (mean 0.2 cm, range 0.1–0.3 cm) (P < 0.01). While outer rings were circular or elliptical in shape with smooth contours, inner rings had a lobular configuration with irregular thickness and contours. The degrees of enhancement were significantly stronger with inner rings than with outer rings (P < 0.01). In histopathological correlation of five patients who underwent total excision, inner and outer rings corresponded to peridegenerative areas and fibrous capsules, respectively.

Conclusion:

The black geode sign may be fairly specific to extracranial schwannomas on gadolinium‐enhanced MR images. J. Magn. Reson. Imaging 2013;37:830–835. © 2012 Wiley Periodicals, Inc.     

Dynamic contrast-enhanced MR imaging and MR-guided bone biopsy on a 0.23T open imager

Objective:To assess the feasibility of MR-guided bone biopsies.Methods::Thirty-six consecutive patients with known or suspected benign or malignant bone lesions underwent comprehensive MR imaging.A dynamic contrast-enhanced sequence followed by stationary Ti-weighted sequences were obtained and MR-guided bone biopsy of the tumor at the site with fastest enhancement was performed using an open 0.23 T MR imager.Results:All MR-guided bone biopsies samples were estimated to be sufficient by the pathologists.The biopsy specimens were diagnostic in 34 of 36 cases.Conclusion:MR-guided bone biopsies combined with dynamic contrast-enhanced imaging are feasible and safe for the diagnostic investigation of equivocal bone lesions.     

MR signal intensity characteristics in Legg-Calvé-Perthes disease. Value of fat-suppressed (STIR) images and contrast-enhanced T1-weighted images

PURPOSE: To evaluate the MR signal intensity characteristics in Legg-Calvé-Perthes disease on fat-suppressed (STIR) images and contrast-enhanced T1-weighted spin-echo images, and to develop criteria for the administration of contrast material. MATERIAL AND METHODS: Twenty children with Legg-Calvé-Perthes disease underwent conventional radiography and MR imaging of the hip utilizing fat-suppressed (STIR) sequences and T1-weighted spin-echo sequences before and after i.v. contrast administration. The signal intensity characteristics of the femoral head and the proximal femoral metaphysis were assessed retrospectively by two pediatric radiologists. RESULTS: Evaluation of the MR images revealed six different signal patterns within the femoral head: 1) isointense signal on all images; 2) complete signal void on all images; 3) hyperintense signal on STIR images with; or 4) without contrast enhancement on T1-weighted spin-echo images; 5) isointense signal on STIR images with; or 6) without contrast enhancement on T1-weighted images. Within the metaphysis three different signal patterns were differentiated. CONCLUSION: Combination of fat-suppressed (STIR) sequences and T1-weighted pre- and post-contrast sequences allows an accurate evaluation of Legg-Calvé-Perthes disease. In patients without signal alterations or complete signal loss on fat-suppressed and T1-weighted spin-echo images, administration of i.v. contrast is not necessary. In case of bone marrow edema on fat-supressed images, contrast-enhanced T1-weighted images are required to identify viable osseous fragments.     

Anterior temporal changes on MR images of children with hippocampal sclerosis: an effect of seizures on the immature brain?

BACKGROUND AND PURPOSE: Ipsilateral loss of anterior temporal gray-white matter definition, due mainly to white matter signal intensity abnormality, is frequently seen on MR images of patients with hippocampal sclerosis. Our aim was to determine the prevalence and clinical correlations of these anterior temporal changes in pediatric cases of hippocampal sclerosis and to determine whether cumulative damage from seizures is important for their development. METHODS: We reviewed the MR images and clinical details of 54 children (age range, 1.5-19 years) with typical hippocampal sclerosis. Specific imaging features noted included hippocampal sclerosis, anterior temporal changes, anterior temporal atrophy, and extra-hippocampal abnormality. RESULTS: Thirty-one (57%) of 54 children with hippocampal sclerosis had associated ipsilateral anterior temporal changes. Ipsilateral anterior temporal atrophy was associated with anterior temporal changes (P <.03). Children whose images showed anterior temporal changes were younger at onset of epilepsy (P <.01) and younger at antecedent cerebral insult (P <.03) than those with normal anterior temporal lobes. Most (84%) children whose images showed anterior temporal changes had experienced the onset of epilepsy or antecedent cerebral insult before the age of 2 years (P <.0009). Eighty-one percent of children with anterior temporal changes shown on their images experienced seizures at the time of antecedent insult. CONCLUSION: Ipsilateral anterior temporal changes identical to those observed in adult cases are seen on the MR images of young children with hippocampal sclerosis, with a similar prevalence, and are associated with either epilepsy onset or seizure-related cerebral insult before the age of 2 years. We suggest that the loss of gray-white matter definition may represent a persistent immature appearance, including an abnormality of myelin or myelination, possibly a result of seizures occurring during maturation of the temporal pole.     

Twisted ovarian fibroma with high signal intensity on T1-weighted MR image: a new sign of torsion of ovarian tumors?

Torsion of ovarian tumors is often difficult to diagnose, because of non-specific clinical, laboratory, and imaging findings. We report a case of twisted ovarian fibroma whose main characteristic was the presence of large areas of high signal intensity on both T1- and T2-weighted MR images due to the passive congestion of the mass. This previously unreported finding should be considered a sign of ovarian torsion and may facilitate prompt surgical intervention.     

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.     

Lateral down-sloping of the acromion: A useful MR sign?

Objective:

The anterior acromion may appear to slope downward in a lateral direction on coronal-oblique magnetic resonance (MR) images of the shoulder. We sought to determine the significance of this finding as a marker of rotator cuff impingement.

Patients and methods:

MR studies of 58 subjects (26 with impingement, 32 with glenohumeral instability) were retrospectively analysed. Subjective down-sloping of the acromion was compared to standardized acromial measurements made on MR (acromial axis, width of the anterior acromion, and distance of the acromioclavicular joint from the superior glenoid) and clinical diagnosis.

Results:

Interobserver variance for lateral down-sloping was fair (κ = 0.5). One reader's assessment of lateral down-sloping of the acromion correlated with standardized MR measurements. Subjective lateral down-sloping of the acromion did not, however, correlate with impingement.

Conclusion:

The subjective finding of a laterally down-sloping acromion on coronal-oblique MR images, while partially validated by standardized measurements, is not predictive of impingement syndrome.     

“Dynamic spot sign” on CT perfusion source images predicts haematoma expansion in acute intracerebral haemorrhage

Objectives

To evaluate the association between dynamic progressive enhancing foci (“dynamic spot sign”) in acute haematoma on CT perfusion source images (CTP-SI) and haematoma expansion.

Methods

One hundred twelve consecutive patients with spontaneous intracerebral haemorrhage according to unenhanced CT, CTP and CT angiography within 6 h of symptom onset were prospectively evaluated. Patients were dichotomised according to the presence/absence of the dynamic spot sign on CTP-SI in haematoma. The predictive value of haematoma expansion was analysed.

Results

Haematoma expansion was detected in 28 patients (25.0 %) on follow-up unenhanced CT images. Thirty patients (26.8 %) demonstrated the dynamic spot sign on CTP-SI, about 83.3 % of patients with haematoma expansion (P?<?0.001). Sensitivity, specificity, positive predictive value, negative predictive value and kappa value for expansion were 89.3 %, 94.0 %, 96.3 %, 83.3 % and 0.814, respectively. In multiple regression, the presence of the CTP dynamic spot sign within acute haematomas independently predicted haematoma expansion; the univariate analysis OR value was 131.667 (29.386–590.289), P?<?0.0001. Moreover, the multivariate analysis CTP dynamic spot sign OR value was 203.996 (32.123–1295.488), P?<?0.0001.

Conclusions

The CTP-SI dynamic spot sign is associated with acute haematoma expansion, is more direct in showing active ongoing bleeding and has a higher predictive value than the CTA spot sign.

Key Points

? It is important to identify potential progression of spontaneous intracerebral haemorrhage. ? Dynamic enhancement within CT perfusion source images is associated with haemorrhage expansion. ? The CTP dynamic spot sign may be present throughout arterial to venous phase imaging. ? The CTP dynamic spot sign carries a higher predive value for haematoma expansion than CTA.