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SUMMARY: Interventional neuroradiology procedures are a valuable asset in the diagnosis, treatment, and surgical management of various disorders affecting the extracranial head and neck. A detailed understanding of cross-sectional and vascular anatomy and an awareness of potential collateral pathways between extracranial and intracranial vessels are essential for ensuring safe and successful procedures. With the use of high-quality imaging and a meticulous technique, the incidence of major complications is extremely low.

A 32-year-old pregnant woman developed a progressive right sixth cranial nerve palsy as an isolated finding. Brain MRI disclosed a discrete lobulated lesion centered in the right Meckel's cave with intermediate signal on T1, high signal on T2, and diffusion characteristics similar to those of cerebrospinal fluid on apparent diffusion coefficient mapping. The initial radiologic diagnosis was schwannoma or meningioma. No intervention occurred. Shortly after cesarean delivery, the abduction deficit began to lessen spontaneously. One month later, the abduction deficit had further improved; 7 months later it had completely resolved. Repeat MRI after delivery failed to disclose the lesion, which was now interpreted as consistent with an arachnoid cyst arising within Meckel's cave. Twenty-one similar cases of Meckel's cave arachnoid cyst or meningocele have been reported, 7 found incidentally and 14 causing symptoms, 2 of which produced ipsilateral sixth cranial nerve palsies. All previously reported symptomatic patients were treated surgically. This is the first report of an arachnoid cyst arising from Meckel's cave in pregnancy and having spontaneous resolution.

A computerized system for segmenting lesions in head and neck CT scans was developed to assist radiologists in estimation of the response to treatment of malignant lesions. The system performs 3D segmentations based on a level set model and uses as input an approximate bounding box for the lesion of interest. In this preliminary study, CT scans from a pre-treatment exam and a post one-cycle chemotherapy exam of 13 patients containing head and neck neoplasms were used. A radiologist marked 35 temporal pairs of lesions. 13 pairs were primary site cancers and 22 pairs were metastatic lymph nodes. For all lesions, a radiologist outlined a contour on the best slice on both the pre- and post treatment scans. For the 13 primary lesion pairs, full 3D contours were also extracted by a radiologist. The average pre- and post-treatment areas on the best slices for all lesions were 4.5 and 2.1 cm 2 , respectively. For the 13 primary site pairs the average pre- and post-treatment primary lesions volumes were 15.4 and 6.7 cm 3 respectively. The correlation between the automatic and manual estimates for the pre-to-post-treatment change in area for all 35 pairs was r=0.97, while the correlation for the percent change in area was r=0.80. The correlation for the change in volume for the 13 primary site pairs was r=0.89, while the correlation for the percent change in volume was r=0.79. The average signed percent error between the automatic and manual areas for all 70 lesions was 11.0±20.6%. The average signed percent error between the automatic and manual volumes for all 26 primary lesions was 37.8±42.1%. The preliminary results indicate that the automated segmentation system can reliably estimate tumor size change in response to treatment relative to radiologist's hand segmentation.

A 16-year-old boy who was briefly asystolic and hypotensive after a motor vehicle accident complained of abnormal vision after recovering consciousness. Visual acuity was normal, but visual fields were severely constricted without clear hemianopic features. The ophthalmic examination was otherwise normal. Brain MRI performed 11 days after the accident showed no pertinent abnormalities. At 6 months after the event, brain MRI demonstrated brain volume loss in the primary visual cortex and no other abnormalities. One year later, visual fields remained severely constricted; neurologic examination, including formal neuropsychometric testing, was normal. This case emphasizes the fact that hypoxic-ischemic encephalopathy (HIE) may cause enduring damage limited to primary visual cortex and that the MRI abnormalities may be subtle. These phenomena should be recognized in the management of patients with HIE.

BACKGROUND: The blood brain barrier (BBB) makes it difficult for oral or intravenous chemotherapy to achieve therapeutic concentrations in brain parenchyma. Regadenoson is an adenosine receptor agonist which transiently disrupts the BBB, allowing systemically administered high molecular weight dextran (MW 70kD) to enter normal rodent brain. Our recent studies with this compound suggest that temozolomide concentrations in rodent brain are also increased by regadenoson. This FDA approved agent is used routinely for cardiac stress tests in patients unable to exercise along with visipaque and cardiac computed tomography (CT) imaging. Visipaque (MW 1550) typically only enters brain where there is significant disruption of the BBB. This study is being conducted to determine if regadenoson will allow more contrast to enter normal human brain. METHODS: Patients without known intracranial disease who were undergoing clinically indicated pharmacologic cardiac stress tests (visipaque with cardiac CT followed by visipaque with regadenoson and cardiac CT) were eligible. This IRB approved study only added brain CT pre- and post-regadenoson. Contrast delivery was measured in hounsfield units (HU), at the level of the basal ganglia, within the cortex, deep gray and white matter. A total of 27 patients are required to assist in comparison analysis of regional contrast uptake. A matched-pairs t-test was performed to determine if the difference was significant. RESULTS: Five of the 27 patients have been accrued and analyzed. There was no difference in contrast following visipaque alone and visipaque with regadenoson (29.3HU vs 30.2HU respectively, P = 0.06). CONCLUSION: Early results from this ongoing study suggest that even accounting for the additional visipaque dose there is a trend towards increased contrast enhancement following regadenoson administration in patients with presumably normal brains. Transient disruption of the BBB to facilitate drug entry using an FDA approved agent could be of significant importance to the field of neuro-oncology.

Summary: The purpose of this report is to add support to the growing literature that there is a correlation between radiation and cavernomas of the brain, particularly if the radiation is received in childhood, as well as to increase awareness of this correlation in the radiology community. Retrospective review of our experience returned five patients who received radiation therapy while they were children and developed cavernomas in the irradiated tissues 3–41 years later. Cavernomas should be considered in the differential diagnosis of a hemorrhagic lesion in any patient who has received previous CNS radiation, particularly if he or she underwent radiation therapy in childhood.

Perineural invasion is a common mechanism of spread of head and neck cancers. Imaging plays an important role in detection of this condition because a large number of patients with perineural spread (PNS) are clinically asymptomatic. Accurate detection of PNS requires an understanding of anatomy of commonly involved neural pathways. High level of suspicion on the part of the radiologist, awareness of common imaging signs of PNS and careful attention to imaging technique can aid in earlier detection of this condition.

Summary Background: Chloral hydrate (CH) sedation for magnetic resonance imaging (MRI) is associated with significant failure rates, adverse events and delayed recovery. Pentobarbital (PB), reportedly produces successful sedation in 98% of children undergoing diagnostic imaging. This study compared the efficacy, adverse events and recovery characteristics of CH vs PB in children undergoing MRI. Methods: With Institutional Review Board approval and written consent, children were randomly assigned to receive intravenous (i.v.) PB (maximum 5 mgAEkg )1 in incremental doses) or oral CH (75 mgAEkg )1 ) prior to MRI. Sedation was augmented with 0.05 mgAEkg )1 doses of i.v. midazolam (maximum 0.1 mgAEkg )1 ) as necessary. Adverse effects, including hypoxaemia, failed sedation, paradoxical reactions and behavioural changes, the return of baseline activity, and parental satisfaction were documented. The quality of MRI scans was evaluated by a radiologist blinded to the sedation technique. Results: PB facilitated an earlier onset of sedation (P ¼ 0.001), higher sedation scores (P ¼ 0.01), and less need for supplemental midazolam compared with CH. Severe hypoxaemia occurred in two children (6%) in the PB group. Fourteen per cent of the PB group experienced a paradoxical reaction, 9% sedation failure and 11% major motion artefact, compared with 0% (P ¼ 0.05), 3 and 2% (P ¼ NS), respectively, in the CH group. CH and PB were both associated with a high incidence of motor imbalance, and agitation. However, children who received PB had a slower return to baseline activity (P ¼ 0.04). Conclusions: Although PB facilitated a quicker sedation onset and reduced the requirement for supplemental sedation, it produced a higher incidence of paradoxical reaction and prolonged recovery with a similar failure rate compared with CH.

Perfusion computed tomography (CT) is a relatively new technique that allows rapid qualitative and quantitative evaluation of cerebral perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The technique is based on the central volume principle (CBF = CBV/MTT) and requires the use of commercially available software employing complex deconvolution algorithms to produce the perfusion maps. Some controversies exist regarding this technique, including which artery to use as input vessel, the accuracy of quantitative results, and the reproducibility of results. Despite these controversies, perfusion CT has been found to be useful for noninvasive diagnosis of cerebral ischemia and infarction and for evaluation of vasospasm after subarachnoid hemorrhage. Perfusion CT has also been used for assessment of cerebrovascular reserve by using acetazolamide challenge in patients with intracranial vascular stenoses who are potential candidates for bypass surgery or neuroendovascular treatment, for the evaluation of patients undergoing temporary balloon occlusion to assess collateral flow and cerebrovascular reserve, and for the assessment of microvascular permeability in patients with intracranial neoplasms. This article is a review of the technique, clinical applications, and controversies surrounding perfusion CT.

A 4-year-old girl presented with hearing loss in her left ear that had begun 1 year earlier. She had chronic otitis media of the left ear 2 years ago, which was treated with antibiotics and insertion of a tympanostomy tube. She also had one instance of substantial bleeding from the left ear during the course of otitis media. She did not have a history of meningitis. The findings of an otoscopic examination were unremarkable. Audiologic evaluation revealed profound conductive hearing loss in the left ear but normal hearing in the right. Computed tomographic (CT) (Hispeed; GE Medical Systems, Milwaukee, Wis) evaluation of the temporal bones was performed, and 1-mm sections were obtained in the transverse and coronal imaging planes. All images were subjected to unilateral retargeting and postprocessing with a thin-section bone algorithm and a small field of view (9.6 cm). Relevant CT scans of the left temporal bone were obtained. The findings of a CT examination of the right temporal bone were unremarkable.