Venous injury in abusive head trauma.

BACKGROUND: Abusive head trauma (AHT) is an important cause of serious brain injury in infants and young children who have characteristic clinical and imaging findings that are discordant with the clinical history provided. Recent attention has focused on abnormalities of the cranial venous sinuses and cortical veins, both on MRI and at autopsy. Although many have interpreted these to be secondary to the AHT, some have recently argued that these venous abnormalities represent primary cortical sinus and venous thrombosis that leads secondarily to subdural hemorrhage and secondary brain injury. Direct trauma to the veins and sinuses has been reported at autopsy in AHT, but there has been no systematic study of venous abnormalities in cases of AHT. OBJECTIVE: The purpose of this study was to define the incidence and characteristics of venous and sinus abnormalities in AHT. MATERIALS AND METHODS: We included all children <36 months of age who were diagnosed with abusive head trauma between 2001 and 2012 and who had MRI and magnetic resonance (MR) venography as part of their diagnostic workup. We analyzed age, gender and clinical findings. MRI and MR venography were analyzed independently by two neuroradiologists with a focus on abnormalities involving the intracranial veins and venous sinuses. RESULTS: A total of 45 children were included. The median age was 3 months (range 15 days to 31 months) and 28 were boys (62%). Clinical findings included retinal hemorrhage in 71% and extracranial fractures in 55%. CT or MRI demonstrated subdural hemorrhage in 41 (91%); none had subdural effusions. In 31 cases (69%) MR venography demonstrated mass effect on the venous sinuses or cortical draining veins, with either displacement or partial or complete effacement of the venous structures from an adjacent subdural hematoma or brain swelling. We also describe the lollipop sign, which represents direct trauma to the cortical bridging veins and was present in 20/45 (44%) children. CONCLUSION: Evidence of displacement or compression of cortical veins and sinuses from subdural hemorrhage or edema on MR venography was present in the majority of children with abusive head trauma. Evidence of direct trauma to the veins (lollipop sign) was identified in nearly half of cases. It is important to understand the superimposed effects of subdural hematoma and brain swelling on the veins and sinuses to differentiate it from cortical sinus and venous thrombosis.

Susceptibility weighted imaging: a new tool in magnetic resonance imaging of stroke.

Susceptibility weighted imaging (SWI) is a magnetic resonance (MR) technique that is exquisitely sensitive to paramagnetic substances, such as deoxygenated blood, blood products, iron, and calcium. This sequence allows detection of haemorrhage as early as 6h and can reliably detect acute intracerebral parenchymal, as well as subarachnoid haemorrhage. It detects early haemorrhagic transformation within an infarct and provides insight into the cerebral haemodynamics following stroke. It helps in the diagnosis of cerebral venous thrombosis. It also has applications in the work-up of stroke patients. The sequence helps in detecting microbleeds in various conditions, such as vasculitis, cerebral autosomal dominant arteriopathy, subacute infarcts and leucoencephalopathy (CADASIL), amyloid angiopathy, and Binswanger's disease. The sequence also aids in the diagnosis of vascular malformations and perinatal cerebrovascular injuries. This review briefly illustrates the utility of this MR technique in various aspects of stroke diagnosis and management.

Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma.

BACKGROUND AND PURPOSE: Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas. MATERIALS AND METHODS: In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining. RESULTS: There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01). CONCLUSION: Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.

'Eiffel-by-Night': A New MR Sign Demonstrating Reactivation in Idiopathic Hypertrophic Pachymeningitis.

A forty- seven-year-old man presented with chronic headache with lower cranial nerve palsies of ten year duration with recent aggravation of symptoms. MRI revealed hypointensity - predominantly of the posterior falx cerebri and the tentorium cerebelli - on all sequences with intense peripheral contrast enhancement on CE SE T1, which on coronal images mimicked the illuminated Eiffel tower by night.

Spurious absence of signal on 3D time-of-flight MR angiograms on 1 and 3 tesla magnets in cerebral arteries associated with a giant ophthalmic segment aneurysm: the need for alternative techniques.

There are many high-resolution MR angiographic techniques available today for the evaluation of circle of Willis. We report a case of bilateral aneurysms of the carotico-ophthalmic segment, the left one being a giant aneurysm, in a 41-year-old woman. She underwent different MRA sequences on both 1 and 3Tesla magnets and a digital subtraction angiography. 3D time-of-flight angiograms can give spurious information on giant aneurysms and other techniques like phase contrast and dynamic contrast enhanced angiographies can supplement if not replace it. High field strength improves the objective quality of MR angiograms, but in the case of large aneurysms, intra aneurysmal and distal vessel signal loss can be a significant problem.