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Open access

Flexible in-cavity MRI receiving coil for ultra–high-resolution imaging of the pituitary gland

Siyuan Liu, Kunal S. Patel, Sophie Peeters, Jiahao Lin, Aislyn C. DiRisio, Harry V. Vinters, Rob N. Candler, Kyunghyun Sung, and Marvin Bergsneider

OBJECTIVE

The objective of this study was the preclinical design and construction of a flexible intrasphenoid coil aiming for submillimeter resolution of the human pituitary gland.

METHODS

Sphenoid sinus measurements determined coil design constraints for use in > 95% of adult patients. Temperature safety parameters were tested. The 2-cm-diameter coil prototype was positioned in the sphenoid sinus of cadaveric human heads utilizing the transnasal endoscopic approach that is used clinically. Signal-to-noise ratio (SNR) was estimated for the transnasal coil prototype compared with a standard clinical head coil. One cadaveric pituitary gland was explanted and histologically examined for correlation to the imaging findings.

RESULTS

With the coil positioned directly atop the sella turcica at a 0° angle of the B0 static field, the craniocaudal distance (21.2 ± 0.8 mm) was the limiting constraint. Phantom experiments showed no detectable change in temperature at two sites over 15 minutes. The flexible coil was placed transnasally in cadaveric specimens using an endoscopic approach. The image quality was subjectively superior at higher spatial resolutions relative to that with the commercial 20-channel head coil. An average 17-fold increase in the SNR was achieved within the pituitary gland. Subtle findings visualized only with the transnasal coil had potential pathological correlation with immunohistochemical findings.

CONCLUSIONS

A transnasal radiofrequency coil feasibly provides a 17-fold boost in the SNR at 3 T. The ability to safely improve the quality of pituitary imaging may be helpful in the identification and subsequent resection of small functional pituitary lesions.

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Sociodemographic changes over 25 years of pediatric epilepsy surgery at UCLA

Clinical article

Jason S. Hauptman, Andrew Dadour, Taemin Oh, Christine B. Baca, Barbara G. Vickrey, Stefanie D. Vassar, Raman Sankar, Noriko Salamon, Harry V. Vinters, and Gary W. Mathern

Object

Low income, government insurance, and minority status are associated with delayed treatment for neurosurgery patients. Less is known about the influence of referral location and how socioeconomic factors and referral patterns evolve over time. For pediatric epilepsy surgery patients at the University of California, Los Angeles (UCLA), this study determined how referral location and sociodemographic features have evolved over 25 years.

Methods

Children undergoing epilepsy neurosurgery at UCLA (453 patients) were classified by location of residence and compared with clinical epilepsy and sociodemographic factors.

Results

From 1986 to 2010, referrals from Southern California increased (+33%) and referrals from outside of California decreased (−19%). Over the same period, the number of patients with preferred provider organization (PPO) and health maintenance organization (HMO) insurance increased (+148% and +69%, respectively) and indemnity insurance decreased (−96%). Likewise, the number of Hispanics (+117%) and Asians (100%) increased and Caucasians/whites decreased (−24%). The number of insurance companies decreased from 52 carriers per 100 surgical patients in 1986–1990 to 19 per 100 in 2006–2010. Patients living in the Eastern US had a younger age at surgery (−46%), shorter intervals from seizure onset to referral for evaluation (−28%) and from presurgical evaluation to surgery (−61%) compared with patients from Southern California. The interval from seizure onset to evaluation was shorter (−33%) for patients from Los Angeles County compared with those living in non-California Western US states.

Conclusions

Referral locations evolved over 25 years at UCLA, with more cases coming from local regions; the percentage of minority patients also increased. The interval from seizures onset to surgery was shortest for patients living farthest from UCLA but still within the US. Geographic location and race/ethnicity was not associated with differences in becoming seizure free after epilepsy surgery in children.

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Choroid plexus hyperplasia: surgical treatment and immunohistochemical results

Case report

Zachary A. Smith, Parham Moftakhar, Dennis Malkasian, Zhenggang Xiong, Harry V. Vinters, and Jorge A. Lazareff

✓Diffuse villous hyperplasia of the choroid plexus is a rare but potential source of nonobstructive hydrocephalus. In addition to discussing the authors' staged surgical approach and medical management decisions in a patient with this rare and challenging condition, immunohistochemical studies of the choroid plexus epithelium are presented to examine the pathophysiological factors involved in abnormal cerebrospinal fluid (CSF) production in this disease.

The patient, a 15-month-old girl born at 36 weeks' gestation, underwent a bilateral craniotomy with resection of the choroid plexus to treat her villous hyperplasia. Immunohistochemical studies of the resected choroid plexus were conducted for the purpose of examining the carbonic anhydrase II (CAII) enzyme and the aquaporin 1 (AQP1) membrane protein. Results were compared with immunohistochemical studies conducted in a small series of autopsy specimens of normal human choroid plexuses. There was no change in the immunoreactivity of CAII in the patient with villous hyperplasia compared with normal controls, whereas AQP1 immunoreactivity was significantly weaker in the patient compared with normal controls. Postoperatively, the patient's CSF overproduction resolved and her neurological symptoms improved over time.

Shunting techniques and presently available pharmaceutical treatments alone do not provide adequate treatment of high-output CSF conditions. Surgical removal of the affected choroid plexus is a feasible and effective treatment. Results of the immunohistochemical studies reported here support the suggestion that the CAII enzyme is retained in villous hyperplasia of the choroid plexus. However, there appears to be decreased expression and perhaps downregulation of AQP1 in villous hyperplasia compared with normal choroid plexus. Future studies may elucidate the significance of these observations.

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Thrombus organization and healing in an experimental aneurysm model. Part II. The effect of various types of bioactive bioabsorbable polymeric coils

Ichiro Yuki, Daniel Lee, Yuichi Murayama, Alexander Chiang, Harry V. Vinters, Ichiro Nishimura, Chiachien J. Wang, Akira Ishii, Benjamin M. Wu, and Fernando Viñuela

Object

Bioabsorbable polymeric material coils are being used in the endovascular treatment of aneurysms to achieve better thrombus organization than is possible using bare platinum coils. We used immunohistochemical and molecular biological analysis techniques in experimental aneurysms implanted with three different bioabsorbable polymer coils and platinum coils.

Methods

The degradation kinetics of nine polymer candidates for further analysis were first analyzed in vitro, and three materials with different degradation rates were selected. Seventy-four aneurysms were created in 37 swine using the venous pouch technique. The aneurysms were surgically implanted with one of the materials as follows (time points = 3, 7, and 14 days): Group 1, Guglielmi detachable coils (platinum); Group 2, Polysorb (90:10 polyglycolic acid [PGA]/polylactic acid); Group 3, Maxon (PGA/trimethylene carbonate); and Group 4, poly-l-lactic acid. Histological, immunohistochemical, and cDNA microarray analyses were performed on tissue specimens.

Results

Groups 1 and 4 showed minimal inflammatory response adjacent to the coil mass. In Group 2, Polysorb elicited a unique, firm granulation tissue that accelerated intraaneurysmal thrombus organization. In Group 3 intermediate inflammatory reactions were seen. Microarray analysis with Expression Analysis Sytematic Explorer software showed functional-cluster-gene activation to be increased at Day 7, preceding the histologic manifestation of polymer-induced granulation tissue at Day 14. A profile of expression changes in cytokine-related and extracellular membrane–related genes was compiled.

Conclusions

Degradation speed was not the only factor determining the strength of the biological response. Polysorb induced an early, unique granulation tissue that conferred greater mechanical strength to the intraaneurysmal coil–thrombus complex. Enhancing the formation of this polymer-induced granulation tissue may provide a new direction for improving long-term anatomical outcomes in cases involving aneurysms embolized with detachable coils.

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Thrombus organization and healing in the swine experimental aneurysm model. Part I. A histological and molecular analysis

Daniel Lee, Ichiro Yuki, Yuichi Murayama, Alexander Chiang, Ichiro Nishimura, Harry V. Vinters, Chiachien J. Wang, Yih-Lin Nien, Akira Ishii, Benjamin M. WU, and Fernando Viñuela

Object

The authors describe the process of thrombus organization in the swine surgical aneurysm model.

Methods

Lateral carotid artery aneurysms with immediately induced thrombosis were created in 31 swine for a time-course study. Aneurysms were evaluated at 1, 3, 7, 14, 30, and 90 days after they were created. Histological analyses included quantitative immunohistochemical studies and evaluation of collagen deposition. Complementary DNA microarray analysis was performed for gene expression profiling. The lists of up- and downregulated genes were cross-matched with lists of genes known to be associated with cytokines or the extracellular matrix. The expression of selected genes was quantified using real-time polymerase chain reaction. Functional clustering was performed with the Expression Analysis Systematic Explorer (EASE) bioinformatics package.

Results

Histological analysis demonstrated leukocyte and macrophage infiltration in the thrombus at Day 3, myofibroblast infiltration at Days 7 to 14, and progressive collagen deposition and contraction thereafter. Tissue organization occurred in a centripetal fashion. A previously undescribed reticular network of connective tissue was observed at the periphery of the aneurysm at Day 3. Macrophages appeared critical to this thrombus organization. A total of 1109 genes were significantly changed from reference time zero during the time course: CXCL14, which produces a monocyte-specific chemokine, was upregulated over 100-fold throughout the time course; IGF1 was upregulated fourfold at Day 7, whereas IGFBP2 was downregulated approximately 50% at Days 7 and 14. Osteopontin (SPP1) upregulation increased from 30-fold at Day 30 to 45-fold at Day 14. The EASE analysis yielded eight functional classes of gene expression.

Conclusions

This investigation provides a detailed histological and molecular analysis of thrombus organization in the swine aneurysm model. The companion study will describe the effect of embolic bioabsorbable polymers on this process.

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Cerebral hemispherectomy in pediatric patients with epilepsy: comparison of three techniques by pathological substrate in 115 patients

Shon W. Cook, Snow T. Nguyen, Bin Hu, Sue Yudovin, W. Donald Shields, Harry V. Vinters, Barbara M. Van de Wiele, Rick E. Harrison, and Gary W. Mathern

Object. Cerebral hemispherectomy for intractable seizures has evolved over the past 50 years, and current operations focus less on brain resection and more on disconnection. In addition, cases involving cortical dysplasia and Rasmussen encephalitis are being identified and surgically treated in younger individuals. Few studies have been conducted to compare whether there are perioperative differences based on hemispherectomy technique and/or pathological substrate in pediatric patients with epilepsy.

Methods. In this study the authors compared, stratified by disease, anatomical (37 cases) and Rasmussen functional hemispherectomy (32 cases) with a new modified lateral hemispherotomy (46 cases). Pathological processes included cortical dysplasia (55 cases), Rasmussen encephalitis (21 cases), infarction/ischemia (27 cases), and other/miscellaneous (12 cases). The authors found differences in perioperative clinical factors based on operative technique and/or pathological substrate. In terms of technique, the lateral hemispherotomy was associated with the least intraoperative blood loss, shortest intensive care unit stay, and lowest complication rate. The anatomical hemispherectomy was associated with the longest hospital stay, delayed oral food intake, highest postsurgery fevers, and the highest incidence of shunt requirement. The functional hemispherectomy was associated with the highest reoperation rate for recurrent seizures (25%). In terms of pathology, patients with cortical dysplasia were the youngest at surgery, suffered the greatest amount of blood loss, and required the longest operative/anesthesia times compared with the other pathologically defined groups. Postoperative seizure control (range 0.5–2 years) was not statistically different according to technique or disease process and was similar to that in cases of pediatric temporal lobe epilepsy.

Conclusions. The authors found differences in perioperative risks and hospital course but not postsurgery seizure control, which vary by hemispherectomy technique and/or disease process. The modified lateral hemispherotomy approach offers various advantages related to operative blood loss and reoperation compared with anatomical and functional hemispherectomies that are especially relevant in younger patients with cortical dysplasia and Rasmussen encephalitis with small and/or malformed ventricles.

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Stereotactic radiotherapy for the treatment of lymphocytic hypophysitis

Report of two cases

Michael T. Selch, Antonio A. F. DeSalles, Daniel F. Kelly, Leonardo Frighetto, Harry V. Vinters, Cynthia Cabatan-Awang, Robert E. Wallace, and Timothy D. Solberg

✓ Lymphocytic hypophysitis is a rare inflammatory disorder of the pituitary gland. Standard therapy consists of transsphenoidal resection or oral administration of corticosteroid medications. Two patients with symptomatic lymphocytic hypophysitis, which recurred after standard therapy, were treated with low-dose stereotactic radiotherapy. On imaging studies both lesions demonstrated a response to radiation and each patient experienced relief of symptoms. There has been no adverse sequela of the radiation treatment.

The authors conclude that stereotactic radiotherapy represents an effective, noninvasive treatment option for patients with lymphocytic hypophysitis, particularly if the disease is recurrent after surgery or resistant to corticosteroid medications.

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Surgical treatment of limbic epilepsy associated with extrahippocampal lesions: the problem of dual pathology

Michel F. Lévesque, Nobukazu Nakasato, Harry V. Vinters, and Thomas L. Babb

✓ The authors present their review of 178 patients who underwent en bloc temporal lobectomies as surgical treatment for intractable epilepsy. Hippocampal cell density was quantitatively analyzed and the histology of the anterior temporal lobe was reviewed. Fifty-four patients (30.3%) had evidence of extrahippocampal lesions in addition to neuronal cell loss within the hippocampus (the dual pathology group). The pattern of cell loss was analyzed in the remaining 124 cases (69.7%) with no extrahippocampal pathology, and compared with that of the dual pathology group and a control group of four nonepileptic patients.

Hippocampal cell loss was found in almost all epileptic patients compared to the control group. Severe cell loss greater than 30% of control values was found in 88.7% of patients without extrahippocampal lesions, but in only 51.8% of patients with dual pathology. The difference between these two groups was statistically significant (p < 0.001). In the dual pathology group, lesions of different pathology had a significant relationship with the degree of hippocampal cell loss: all 12 patients with glioma had mild cell loss, whereas all 13 patients with heterotopia were associated with severe cell loss. Severity of hippocampal cell loss was also analyzed in relation to seizure history: a prior severe head injury was associated with severe cell loss. Other factors such as seizure duration, secondary generalization, or family history of seizures were not associated with hippocampal damage. Dual pathology may produce a combination of neocortical and temporolimbic epilepsies that warrants a precise definition of the true epileptogenic area prior to surgical treatment.

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Pathology of arteriovenous malformations embolized with isobutyl-2-cyanoacrylate (bucrylate)

Report of two cases

Harry V. Vinters, Gérard Debrun, John C. E. Kaufmann, and Charles G. Drake

✓ There is controversy as to the possible toxic effects of isobutyl-2-cyanoacrylate (bucrylate) when this substance is used for purposes of therapeutic embolization. Two cases are presented in which cerebral arteriovenous malformations were resected, one 42 days and the other a year after bucrylate embolization. In both, pathological examination revealed a brisk intimal foreign-body giant-cell reaction wherever bucrylate was present in a vessel, along with chronic inflammation in the vessel walls and adjacent brain parenchyma. The findings are discussed in the light of other observations on the histotoxicity of bucrylate.