High-resolution MRI to noninvasively characterize drainage around the carotid artery into the cervical lymph nodes.

BACKGROUND AND PURPOSE: Previous studies have proposed multiple parallel channels for waste clearance from the brain, though many gaps remain in our understanding of these systems. In this study, we examined periarterial fluid drainage around intracranial and extracranial segments of the internal carotid arteries (ICAs) from the brain into the cervical lymph nodes using a noninvasive and clinical-based method. METHODS: Eighty-one subjects (45 females, aged 15-80 years old) with nonlesioned epilepsy underwent high-resolution 3-dimensional T2-weighted fluid-attenuated inversion recovery (FLAIR) MRI. We utilized a noninvasive and clinical-based method with a manual semiautomated approach to characterize the periarterial lymphatic system's maximum thickness and signal intensities along the ICAs using high-resolution 3-dimensional FLAIR imaging. We conducted group comparisons and correlation analyses to investigate sex- and age-based trends. Results were corrected with Bonferroni's test for multiple comparisons, and we performed power analysis for sample size calculations. RESULTS: Using high-resolution FLAIR images, we show evidence that fluid drainage emerges around the ICA petrous segment and joins lymphatic flow from cranial nerves in the upper neck, with this flow ultimately draining into the cervical lymph nodes bilaterally. Lymphatic signal at the petrous segment level was significantly thinner in females compared to males bilaterally (w = 413, p = .0001 on the right, w = 356, p < .0001 on the left). Lymphatic drainage around the petrous segments of the ICAs bilaterally was thicker with age in males but not in females. CONCLUSIONS: We describe the in vivo high-resolution imaging characteristics of periarterial fluid drainage along the vessel walls of ICAs. This represents a potentially major channel for brain waste clearance. We also report interesting sex- and age-based trends in these structures within our cohort.

Non-invasive MR imaging of human brain lymphatic networks with connections to cervical lymph nodes.

Meningeal lymphatic vessels have been described in animal studies, but limited comparable data is available in human studies. Here we show dural lymphatic structures along the dural venous sinuses in dorsal regions and along cranial nerves in the ventral regions in the human brain. 3D T2-Fluid Attenuated Inversion Recovery magnetic resonance imaging relies on internal signals of protein rich lymphatic fluid rather than contrast media and is used in the present study to visualize the major human dural lymphatic structures. Moreover we detect direct connections between lymphatic fluid channels along the cranial nerves and vascular structures and the cervical lymph nodes. We also identify age-related cervical lymph node atrophy and thickening of lymphatics channels in both dorsal and ventral regions, findings which reflect the reduced lymphatic output of the aged brain.

Detailed imaging of abducens nerve anatomy using contrast-enhanced 3D-TOF MR angiography.

PURPOSE: Cranial nerves (CNs), particularly CN IV and VI are difficult to visualize with conventional MRI techniques, particularly within the cavernous sinus region. The aim of this study was to evaluate the capacity of high-resolution contrast enhanced 3D time-of-flight (TOF) MR angiography using new generation 3 T imaging technology to provide detailed visualization of CN VI anatomy, particularly within the cavernous sinus and petroclival regions. METHODS: Two neuroradiologists conducted bilateral evaluation of CN VI visibility in 23 patients for nerve segments located in the petroclival segment (dural cave and Dorello's canal), and three divisions of the cavernous sinus. All images were collected using contrast enhanced TOF MR angiography using a new generation 3 T machine. RESULTS: Of the CN VI segments assessed, average visibility of CN VI was best achieved in Dorello's canal. Overall visibility of CN VI within the regions inspected was best achieved in the axial view, with the exception of the dural cave, which was best assessed using the coronal view. We also identified strong agreement in assessment of nerve visibility between the two reviewers. We also identified a putative CN6 duplication and a small schwannoma, highlighting the fidelity of our approach. CONCLUSION: Contrast enhanced 3D TOF MR angiography can visualize CN VI anatomy, particularly within the petrocavernosal region and cavernous sinus with simultaneous visualization of arterial and venous structures. This cannot be easily achieved using traditional MRI techniques. This imaging technique might be used with new generation machines to evaluate CN VI anatomy and pathologies within the petrocavernosal region and cavernous sinus, especially relating to vascular pathologies.

Demonstration of acute retinal ischemia on diffusion weighted magnetic resonance imaging.

In this case, we demonstrate the ability of diffusion weighted magnetic resonance imaging to localize retinal ischemia in a patient with acute vision loss. MRI is widely used for the evaluation of acute stroke, but there has only been one other case report showing the ability of DWI to rapidly localize retinal pathology, including central retinal artery occlusion [1]. Central retinal artery occlusion is an ocular emergency presenting with acute, painless loss of vision as a result of retinal ischemia. This case demonstrates the role of diffusion weighted imaging as an adjunctive test in the prompt diagnosis and management of central retinal artery occlusion. As the technology improves, we anticipate diffusion weighted imaging will become more sensitive for the identification of acute retinal ischemia and other retinal pathologies.

Novel diagnostic imaging features of facial lupus panniculitis: ultrasound, CT, and MR imaging with histopathology correlate.

Lupus panniculitis (LP), also referred to as lupus erythematosus profundus (LEP), is a chronic recurrent inflammation condition of the subcutaneous fat. It occurs in 1 to 3% of patients with systemic lupus erythematosus (SLE) and in 10% of patients with discoid lupus erythematosus (DLE), but can also occur as an entity of its own. Patients with lupus panniculitis usually present with persistent, often tender and painful skin lesions, or subcutaneous nodules, that range from 1 to 5 cm in diameter. The overlying skin may appear erythematous; lesions may become ulcerated, and heal with atrophy, skin depression, dimpling and scaring. Lesions tend to resolve spontaneously and may follow a chronic course of remission and exacerbation that persists for months to years. The imaging features of facial LP are extremely scarce in the literature. We present a case of facial lupus panniculitis and describe the associated characteristic ultrasound, CT, and MR imaging findings along with histopathologic correlation.

Failed caudal block due to physiologic changes associated with a cerebrospinal fluid leak: a case report.

PURPOSE: The sum of the volumes of brain tissue, cerebrospinal fluid (CSF), and intracranial blood remain constant. This tenet of the Monroe-Kellie hypothesis is most often considered in the setting of intracranial hypertension, but it can also be applied in the setting of CSF volume depletion. We used this hypothesis to explain a case of failed caudal block in a patient with an iatrogenic CSF leak. CLINICAL FEATURES: A one-month-old baby (3 kg) born at 35 weeks' gestation presented for right inguinal hernia repair. His past medical history was significant for arthrogryposis (congenital joint contractures in two or more areas of the body) as well as ongoing apneic episodes that required continuous positive airway pressure therapy and neonatal intensive care. An ultrasound confirmed caudal block was completed and within five minutes of the procedure, the patient's heart rate increased, with an accompanying slight increase in T-wave amplitude. Pinch tests revealed anesthesia to the feet bilaterally but insufficient anesthesia to the abdomen. The surgery was delayed but successfully completed under general anesthesia the following week. Magnetic resonance imaging of the brain and spine following the surgery showed a significant CSF leak with engorgement of the epidural venous plexus along the entire spine. These findings were consistent with a CSF leak likely secondary to a prior lumbar puncture (at age 13 days) that was part of the investigation of his respiratory issues. CONCLUSIONS: The possible mechanism of this failed caudal block was high systemic absorption of anesthetic given the epidural venous plexus engorgement thus leaving less anesthetic acting within the CSF and on the exiting spinal nerves. Decreased CSF flow in the thecal sac might also have contributed, as might dilution of the remaining local anesthetic caused by large amounts of leaking CSF within the epidural space.

An experimental model of traumatic nasoethmoidal cerebrospinal fluid fistula.

Cerebrospinal fluid fistula secondary to head trauma is a potentially dangerous problem and precise localization and radical treatment is mandatory. The diagnostic technique is either computed tomography cisternography or MR cisternography. For evaluating the safety of diagnostic modalities and efficacy of treatment especially in terms of surgery, animal studies demonstrating traumatic cerebrospinal fistula model are indispensable not only for neurosurgeons but also for neuroradiologists. The authors in this paper describe a traumatic cerebrospinal fistula in an animal model using rabbits. The cerebrospinal fluid leakage was demonstrated successfully in all eight rabbits and was verified by computed tomography cisternography. The results led us to conclude that rabbit model of traumatic cerebrospinal fluid fistula is safe and has low mortality and morbidity rates. Further studies including larger number of animals should be considered in order to verify safety more accurately.

Follow-up of extracranial vertebral artery stents with Doppler sonography.

OBJECTIVE: The objective of our study was to determine the Doppler sonography findings suggestive of restenosis in the follow-up of patients treated by stent placement in the extracranial vertebral artery. CONCLUSION: Follow-up of vertebral artery stents with Doppler sonography may be performed by direct insonation of the stent or by indirect measurements from the V2 segment (the part of the vertebral artery that courses within the intervertebral foramina). The V2 segment Doppler sonography measurements may guide future examinations and provide essential information regarding the proximally deployed stent.

The effect of an acute decrease in serum estrogen concentration on vessel walls: determination with color and pulsed Doppler ultrasound.

The aim of this study was to determine the effects of an acute decrease in serum estrogen concentration on endothelial function in women with surgically induced menopause through the use of color Doppler ultrasonography. There were 40 women scheduled to undergo total abdominal hysterectomy and bilateral salpingo-oopherectomy who participated in the study; 15 women not undergoing surgery also participated as a control group. Color Doppler ultrasonographic examinations of each surgical patient were obtained 3 days prior to and 7 days after surgery. Baseline measurements of the brachial arteries, including peak systolic velocity, end-diastolic velocity, true mean velocity, arterial diameter, and volume flow, were obtained for each patient. After baseline measurements were established, hyperemia was induced by inflating a blood pressure cuff on each patient's upper arm to suprasystolic pressures for 5 min. To evaluate endothelium-dependent vasodilation, the ultrasonographic appearance of the brachial artery was evaluated after the cuff was deflated and removed from the arm. Measurements of peak systolic velocity, end-diastolic velocity, true mean velocity, arterial diameter, and volume flow were obtained, and were repeated at 1, 3, 5, 10, and 20 min subsequent to removal of the blood pressure cuff. The differences between baseline and maximum values of each Doppler parameter after the cuff deflation were calculated. No significant differences were identified in terms of laboratory findings or systolic and diastolic pressures in pre- and postoperative status of surgical patients, or between surgical patients and the control group. A significant difference in serum estradiol levels during pre- and postoperative periods ( P<0.001) was detected. No significant difference in serum estradiol levels was detected among preoperative surgical patients and members of the control group ( P=0.72). All net changes detected within each group during reactive hyperemia were statistically significant. No significant difference in values was detected among pre-, postoperative, and control subjects. Our study reveals that acute decrease in serum estrogen level does not appear to affect endothelial function; thus, we assume that this is mainly due to the result of postoperative surgical stress.

Effects of oophorectomy and hormone replacement therapy on the pulsatility indices of hepatic and renal arteries.

OBJECTIVE: To investigate the flow velocity waveform changes of the hepatic and renal arteries in women with surgical menopause who received hormone replacement therapy versus those who did not. METHODS: Eighty women who had undergone surgical menopause were divided into 2 groups. The first group (n = 38) consisted of patients who did not receive estrogen treatments after surgery; patients in the second group (n = 42) did receive treatments. The hepatic and renal arteries of patients in both groups were examined by duplex Doppler ultrasonography before the commencement of hormone replacement therapy and after 2 years of treatment, and the pulsatility indices were calculated. RESULTS: No significant differences were detected in the renal and hepatic artery pulsatility indices of patients in the estrogen treatment group (group 2) before and after total abdominal hysterectomy and bilateral salpingo-oophorectomy (P > .05). No significant differences in preoperative and postoperative hepatic arterial pulsatility indices were detected among patients in group 1 (P > .05). Renal artery pulsatility indices measured before and after total abdominal hysterectomy and bilateral salpingooophorectomy did show a statistically significant difference in group 1 (P < .001). In addition, a statistically significant difference was detected before and after surgery in both groups when pulsatility indices were measured at the second-year control dose. CONCLUSIONS: Hepatic arterial pulsatility indices are not affected in postmenopausal women, but renal artery pulsatility indices rise to some extent in women not receiving hormone replacement therapy.