Melanie B. Fukui

Ischemic Core and Penumbra in Human Stroke

Background and Purpose—The ischemic core and penumbra have not been thoroughly characterized after acute cerebral thromboembolic occlusion in humans. Differentiation between areas of potentially viable and irreversibly injured ischemic tissue may facilitate assessment and treatment of stroke patients. Methods—Cerebral blood flow (CBF) was measured in 20 patients with acute middle cerebral artery (MCA) occlusion between 60 and 360 minutes after stroke onset, with the stable xenon computerized tomography (CT) technique. Threshold displays were generated at a single level, and the percentages of hemisphere with CBF ≤6, ≤10, 11 to 20, 21 to 30, and >30 cm3 · 100 g−1 · min−1 were measured. The corresponding images on 12 available follow-up CT scans were similarly assessed to determine the area of final infarct. Comparisons were analyzed with a paired Student’s t test and Pearson’s correlation coefficient. Results—Discrete and confluent areas of CBF ≤20 cm3 · 100 g−1 · min−1 were identified in all patients, ips...

Combined positron emission tomography/computed tomography imaging of recurrent thyroid cancer.

OBJECTIVE: The study goal was to evaluate the use of combined positron emission tomography/computed tomography (PET/CT) imaging for localization of recurrent disease in thyroid cancer patients. STUDY DESIGN AND SETTING: Eight patients with suspected recurrence of thyroid cancer on the basis of elevated serum thyroglobulin or calcitonin levels underwent combined PET/CT imaging on a prototype device. All 8 patients had previously undergone total thyroidectomy and 131I ablation for thyroid carcinoma. Patients with papillary carcinoma had negative 131I scans. RESULTS: Eight patients underwent combined PET/CT scanning. Four (50%) of 8 patients underwent PET/CT indicating recurrence in the head and neck. A total of 11 lesions in these 4 patients were suspicious for recurrence on combined PET/CT imaging. Three patients with 8 lesions suspicious for recurrence on PET/CT underwent surgical removal of disease. All 3 patients had pathologic confirmation of recurrence, with 6 (75.0%) of 8 lesions being positive. CONCLUSION: Combined PET/CT imaging is a valuable tool for the diagnosis and anatomic localization of recurrent thyroid cancer.

Complications of cervical selective nerve root blocks performed with fluoroscopic guidance.

2Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, PA. ervical nerve root blocks have been performed since the late 19th century [1], and the use of the procedure has been increasing over the past decade [2]. Cervical nerve root blocks are used to manage or treat spinal pain, radiculopathy, and complex regional pain syndromes. Many such blocks are performed in outpatient clinics with and without imaging guidance such as fluoroscopy or CT. If imaging guidance is not used, palpable anatomic landmarks are generally used to direct needle placement. Various complications associated with the nerve block procedure have previously been described [3–7]. The most serious reported complications include death, stroke, arrhythmias, sensory or motor loss, meningitis, bleeding, and seizures. To our knowledge, arterial dissection has not previously been reported after a cervical selective nerve root block (SNRB). Our purpose is to present two cases that show potentially devastating outcomes when a cervical SNRB is performed using fluoroscopic guidance and to evaluate possible alternative methods currently available.

Quantitative Cerebral Blood Flow Determinations in Acute Ischemic Stroke Relationship to Computed Tomography and Angiography

BACKGROUND AND PURPOSE The advent of new modalities to treat acute ischemic stroke presents the need for accurate, early diagnosis. In acute ischemic stroke, CT scans are frequently normal or reveal only subtle hypodense changes. This study explored the utility and increased sensitivity of xenonenhanced CT (XeCT) in the diagnosis of acute cerebral ischemia and investigated the relationship between cerebral blood flow (CBF) measurements and early CT and angiographic findings in acute stroke. METHODS The CT scans, XeCT scans, and angiograms of 20 patients who presented within 6 hours of acute anterior circulation ischemic strokes were analyzed. RESULTS CT scans were abnormal in 11 (55%) of 20 patients. XeCT scans were abnormal in all 20 (100%) patients, showing regions of interest with CBF < 20 (mL/100 g per minute) in the symptomatic middle cerebral artery (MCA) territories. The mean CBF in the symptomatic MCA territories was significantly lower than than of the asymptomatic MCA territories (P < .0005). In patients with basal ganglia hypodensities, the mean symptomatic MCA territory CBF was significantly lower than that of patients who did not exhibit these early CT findings (P < .05). The mean symptomatic MCA territory CBF in patients with angiographic M1 occlusions was significantly lower than that of patients whose infarcts were caused by MCA branch occlusions (P < .01). CONCLUSIONS These results show that XeCT is more sensitive than CT in detecting acute strokes and that CBF measurements correlate with early CT and angiographic findings. XeCT may allow for the hyperacute identification of subsets of patients with acute ischemic events who are less likely to benefit and more likely to derive complications from aggressive stroke therapy.

PET/CT imaging in recurrent head and neck cancer

PET/CT offers advantages over PET alone, which is limited by poor anatomic localization and CT alone, which provides morphologic data only. Retrospective fusion of separately acquired PET and CT images allows for potential fusion misregistration in the mobile head and neck between imaging sessions. Indications for PET/CT include recurrent neoplasm, tumor surveillance, and staging. This article will focus on recurrent head and neck neoplasm including, head and neck cancer, thyroid cancer, recurrent skull base tumor. PET/CT may change management in facilitating earlier detection of recurrence than is possible with conventional CT or MR imaging, in guiding biopsy, and in detecting second primary sites and distant metastases. Limitations of PET/CT include physiologic uptake, metabolically active tissue, and muscle contraction during uptake phase. PET/CT, however, is better equipped than is PET alone to mitigate these limitations by precisely localizing FDG uptake to anatomic structures. In addition, small lesions (< 1 cm) may be below scanner resolution and, therefore, a lower SUV (that is < or = 3), may suggest neoplasm. Recent treatment may result in false negative findings, especially when PET is performed within 4 months of radiation therapy. Finally, tumors of low metabolic activity (e.g., salivary gland tumors) may be prone to false negative results. In the future, PET/CT imaging will become more useful in staging head and neck cancer with improved scanner resolution. Development of specific tumor markers may allow for tumor-specific ligands that will increase sensitivity to head and neck neoplasia. Treatment targeting for radiation therapy is an application that is likely to become widely used.

Superphysiologic FDG Uptake in the Non-Paralyzed Vocal Cord. Resolution of a False-Positive PET Result with Combined PET-CT Imaging.

The application of positron emission tomography imaging with 18F-fluorodeoxyglucose (FDG) to the extracranial head and neck has been proven to be effective in the detection and staging of malignancy. The FDG uptake of normal laryngeal tissue is symmetric and low, while benign lesions typically have only slight increases in FDG uptake. We report a case of asymmetric, superphysiologic FDG uptake in the contralateral vocal cord of a patient with a unilateral vocal cord paralysis secondary to sacrifice of the recurrent laryngeal nerve during pneumonectomy for lung cancer. The FDG uptake of the non-paralyzed vocal cord was increased multiple-fold, placing it well within the range of malignancy. Use of unique, combined PET-CT imaging localized the high FDG uptake to the non-paralyzed vocal cord, and laryngoscopy confirmed no evidence of malignancy in the vocal cord. This case demonstrates that a benign cause of false-positive FDG-PET imaging may be encountered during evaluation of the extracranial head and neck for malignancy. We aim to alert the reader to this potential pitfall in the interpretation of FDG-PET imaging, which can be resolved with the use of combined PET-CT imaging and clinical correlation.

Survival of patients with high grade glioma treated with intrathecal thiotriethylenephosphoramide for ependymal or leptomeningeal gliomatosis

The diagnosis of leptomeningeal dissemination of malignant glioma (meningeal gliomatosis) is associated with poor survival. Intrathecal (IT) chemotherapeutic agents used to achieve tumor control and improve survival include methotrexate, cytosine arabinoside (ara‐C), thiotriethylenephosphoramide (thio‐TEPA), neocarzinostatin, and 3‐[(4‐amino‐2‐methyl‐5‐pyrimidinyl)methyl]‐1‐(2‐chloroethyl)‐1‐nitrosourea hydrochloride (ACNU). Little information exists about survival following administration of IT chemotherapy. The authors report survival data from a series of patients with supratentorial anaplastic astrocytoma (AA) or glioblastoma multiforme (GBM) treated for ependymal or leptomeningeal gliomatosis with IT thio‐TEPA.

Venous angioma adjacent to the root entry zone of the trigeminal nerve: implications for management of trigeminal neuralgia

Abstract. Detection of a venous angioma at the root entry zone is important for surgical planning, so that the neurosurgeon will be aware that both veins and arteries may require microvascular decompression. In selected cases, alternative treatment may be indicated to avoid the potential surgical complication of a venous infarct. Trigeminal neuralgia typically occurs in the middle-aged to elderly population, usually the result of compression of the trigeminal nerve at its root entry zone by an ectatic, aging artery or, less commonly, a regional vein [1, 2, 3]. When associated with a venous angioma at the root entry zone, trigeminal neuralgia usually presents at a younger age [4, 5, 6]. We review the imaging examinations and clinical data of five patients with trigeminal neuralgia who had a venous angioma adjacent to the root entry zone of the trigeminal nerve, and discuss how the imaging findings affected their management.

Memory impairment in elderly individuals with a mildly elevated serum TSH: The role of processing resources, depression and cerebrovascular disease

This study examined whether a mild elevation in serum Thyroid Stimulating Hormone (TSH) in normal older individuals was associated with a cognitive impairment. Participants consisted of 15 individuals with a high- TSH level and 82 with a normal TSH. The high-TSH group performed significantly worse than the normal- TSH group on tests of immediate and delayed verbal recall and on the Mini-Mental State Exam. This decrement was not due to group differences in processing resources nor was it explained by comorbid cerebrovascular disease, depression or anticholinergic drug usage. These results suggest that undetected mild thyroid dysfunction may contribute to the cognitive decrements found in older adults.

Part I: The challenge of functional preservation: an integrated systems approach using diffusion-weighted, image-guided, exoscopic-assisted, transulcal radial corridors

Abstract Surgical access to subcortical lesions in the sensorimotor area can lead to a high degree of cognitive and functional morbidity through injury to white matter fiber tracts. Inherent technological challenges limit resection of lesions in the sensorimotor area. A systematic and integrated approach to address these challenges termed the six-pillar approach has been developed. While individual elements of these pillars have been reported elsewhere, the authors hypothesize that the consistent adoption of standardized imaging, navigation, access, optics and resection technologies as a system identifies and protects eloquent tissue. In addition, this approach allows for the targeted harvest of viable cells to serve as the substrate for molecular regenerative therapy. An illustrative case with resection of a low-grade glioma in the sensorimotor region using the six-pillar approach is included to highlight the strengths of this approach.