Absence of enhancement in a lesion does not preclude primary central nervous system T-cell lymphoma: A case report.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is a non-Hodgkin lymphoma that originates in the central nervous system (CNS) and is exclusively limited to the CNS. Although most PCNSLs are diffuse large B-cell lymphomas, primary CNS T-cell lymphomas (PCNSTLs) are rare. PCNSTLs typically demonstrate some degree of enhancement on contrast-enhanced magnetic resonance imaging (MRI). To the best of our knowledge, non-enhancing PCNSTL has not been reported previously. CASE SUMMARY: A 69-year-old male presented to the neurology department with complaints of mild cognitive impairment and gradual onset of left lower leg weakness over a span of two weeks. Initial MRI showed asymmetric T2-hyperintense lesions within the brain. No enhancement was observed on the contrast-enhanced T1 image. The initial diagnosis was neuro-Behçet's disease. Despite high-dose steroid therapy, no alterations in the lesions were identified on initial MRI. The patient's symptoms deteriorated further. An MRI performed one month after the initial scan revealed an increased lesion extent. Subsequently, brain biopsy confirmed the diagnosis of PCNSTL. The patient underwent definitive combined chemo-radiotherapy. However, the patient developed bacteremia and died of septic shock approximately three months after diagnosis. CONCLUSION: The absence of enhancement in the lesion did not rule out PCNSTL. A biopsy approach is advisable for pathological confirmation.

Post-surgical thyroid bed myofibroma simulating a recurrent papillary thyroid carcinoma: A case report and review of the literature.

RATIONALE: Myofibromas are rare benign spindle cell tumors of the soft tissue, bone, or internal organs that occur at any age. Here, we report a post-surgical thyroid bed myofibroma that mimicked a papillary thyroid carcinoma. PATIENT CONCERNS: A 56-year-old male presented with a mass in the thyroid surgical bed, detected 3 years post thyroidectomy following papillary carcinoma. DIAGNOSIS: Thyroid ultrasonography revealed a well-defined, lobulated, hypoechoic, solid nodule, with large rod-like echogenic foci in the thyroid surgical bed. The development of a postoperative suture granuloma was considered. However, ultrasonography performed 12 months later showed a marked increase in the lesion size. Two fine needle aspiration cytology yielded nondiagnostic results. INTERVENTION: Considering the possibility of local tumor recurrence, surgical resection was performed. OUTCOME: The diagnosis of a myofibroma was confirmed, and no additional treatment was administered. LESSONS: It is challenging to differentiate lesions occurring on the thyroid surgical bed after surgery, from recurrent thyroid cancer. A lesion measuring 6 mm, with a degree of punctate echogenicity, suggests tumor recurrence. Moreover, myofibromas are extremely rare. This case highlights that it is advisable to perform a core needle biopsy in cases of nondiagnostic fine needle aspiration results.

Patient-derived glioblastoma cell lines with conserved genome profiles of the original tissue.

Glioblastoma (GBM) is the most lethal intracranial tumor. Sequencing technologies have supported personalized therapy for precise diagnosis and optimal treatment of GBM by revealing clinically actionable molecular characteristics. Although accumulating sequence data from brain tumors and matched normal tissues have facilitated a comprehensive understanding of genomic features of GBM, these in silico evaluations could gain more biological credibility when they are verified with in vitro and in vivo models. From this perspective, GBM cell lines with whole exome sequencing (WES) datasets of matched tumor tissues and normal blood are suitable biological platforms to not only investigate molecular markers of GBM but also validate the applicability of druggable targets. Here, we provide a complete WES dataset of 26 GBM patient-derived cell lines along with their matched tumor tissues and blood to demonstrate that cell lines can mostly recapitulate genomic profiles of original tumors such as mutational signatures and copy number alterations.

Pancreatic serous cystic neoplasm mimicking intraductal papillary mucinous neoplasm: Two case reports and literature review.

RATIONALE: Serous cystic neoplasms (SCNs) are treated as benign lesions. It is widely known that SCN rarely have a connection with the main pancreatic duct (MPD), which helps differentiate them from other cystic lesions, such as intraductal papillary mucinous neoplasm (IPMN). However, very rare cases where the SCN appears connected to the MPD cause diagnostic confusion. PATIENT CONCERNS: We present 2 patients with SCN (1 male, 54, and 1 female, 42). Both patients were asymptomatic, without abnormal laboratory results. DIAGNOSIS: In both cases, abdominopelvic computed tomography and pancreatic magnetic resonance imaging scans revealed a multilobulated cystic lesion in communication with the MPD. Since the size of each patient's lesion was >3 cm and there was connectivity with the MPD, it was strongly suspected to be a branch duct-type IPMN with worrisome features rather than SCN and surgical intervention was considered. INTERVENTIONS: Both neoplasms were misdiagnosed as IPMN due to appearing connected with the MPD on radiologic imaging. Surgery was performed. OUTCOMES: A final diagnosis of microcystic serous cystadenoma of the pancreas without connectivity of MPD was confirmed in both patients. LESSONS: An unnecessary surgery was performed due to atypical radiologic features in which the pancreatic duct seems to be connected to the pancreatic cystic lesion on magnetic resonance imaging, leading to misdiagnosis of SCN as IPMN. Particular attention should be paid to interpretation of clinicoradiologic findings of pancreatic cystic lesions, especially to the decision of surgical intervention. Also, awareness of presence of the atypical radiologic features of SCN may broaden the knowledge base of radiologists. LESSONS: An unnecessary surgery was performed due to atypical radiologic features in which the pancreatic duct seems to be connected to the pancreatic cystic lesion on magnetic resonance imaging, leading to misdiagnosis of SCN as IPMN. Particular attention should be paid to interpretation of clinicoradiologic findings of pancreatic cystic lesions, especially to the decision of surgical intervention. Also, awareness of presence of the atypical radiologic features of SCN may broaden the knowledge base of radiologists.

Multidisciplinary team approach on tracheoesophageal fistula in a patient with home ventilator.

A 68-year-old man was transferred to our tertiary hospital. Ten years ago, he received radiation therapy for tonsil cancer, and while there was no evidence of recurrence, he suffered from recurrent aspiration. We treated his aspiration pneumonia in the intensive care unit. Prior to his discharge, he received percutaneous dilatational tracheostomy (PDT) before he was transferred to a nursing hospital. Nine months later, he was readmitted owing to tracheoesophageal fistula (TEF). However, he was considered unsuitable for conservative intervention after a multidisciplinary team discussion. Esophageal stent insertion was impossible due to the high level of TEF in the esophagus. Additionally, the size of the TEF could not be covered by an endosponge and endoluminal vacuum therapy, and there was no tracheal stent that could cover his large trachea. The preceding percutaneous enteral gastrostomy (PEG) procedure was required for the primary closure operation of the esophagus; however, family's consent could not be obtained. After 1month, the patient and his family changed their minds and agreed to the procedure and we attempted to perform PEG procedure. However, we could not proceed with PEG owing to stenosis in the inlet of the esophagus. Then, the patient deteriorated clinically and died due to pneumonia with septic shock.

Use of N-butyl cyanoacrylate in the successful transcatheter arterial embolization of an arteriovenous fistula caused by blunt pelvic fracture: A case report and review of literature.

RATIONALE: Traumatic arteriovenous fistulas (AVFs) of the pelvis are uncommon and present with a variety of clinical manifestations; their detection may be difficult. An endovascular approach is usually the first choice of treatment, because surgical intervention is complicated due to the location of the lesions. PATIENT CONCERNS: A 68-year-old man was admitted with severe pelvic pain following a fall. DIAGNOSIS: A pelvic bone fracture (Young and Burgess Classification, lateral compression type II) was revealed on pelvic computed tomography (CT), while a pelvic sidewall hematoma, unaccompanied by any vascular injury, was detected on multidetector CT. INTERVENTIONS: Pelvic angiography revealed an AVF between the internal iliac artery and vein, which was undetected by MDCT. The AVF was successfully treated using transcatheter arterial embolization (TAE) with n-butyl cyanoacrylate (NBCA). OUTCOMES: The patient recovered well and was discharged 4 weeks later. No complications were noted at the 8-month follow-up. LESSONS: AVF may occur as a complication of blunt pelvic bone fracture. A high index of suspicion, angiography, and prompt diagnosis resulted in the successful management of our patient who presented with risk factors. Furthermore, TAE using NBCA enables a minimally invasive and effective treatment of traumatic pelvic AVF.

Successful transcatheter arterial embolization for massive hemorrhage from acquired uterine arteriovenous malformation which occurred as a complication of hysterectomy: A case report.

RATIONALE: Uterine arteriovenous malformation (UVM), which can be congenital or acquired, is a relatively rare disorder that can cause life-threatening hemorrhage. Acquired UVM occurs predominantly after previous uterine procedures; rarely, it may occur after a hysterectomy. Although the best treatment option for UVM remains controversial, transcatheter arterial embolization (TAE) has recently been introduced as a safe and effective treatment. PATIENT CONCERNS: A 34-year-old woman who underwent hysterectomy for uncontrolled postpartum bleeding continued to have hemoperitoneum. DIAGNOSIS: Two days after surgery, massive hemoperitoneum was identified on computed tomography scan, and acquired UVM was diagnosed by angiography. INTERVENTIONS: The patient was successfully treated using TAE with an n-Butyl cyanoacrylate. OUTCOMES: After embolization, hemodynamic stability was achieved. A day after embolization, hemoglobin was 10.2 g/dL, and the patient was discharged from the hospital 4 days thereafter. LESSONS: Although the overall incidence of acquired UVM after hysterectomy is low, bleeding from acquired UVM should be considered as one of the differential diagnoses in the immediate postpartum period, especially when the clinical symptoms do not correlate with the amount of blood loss. A high index of suspicion, prompt diagnosis and intervention, and a multidisciplinary approach in the management were the elements of a successful outcome in this case.

Schwannoma of the thyroid bed: A case report and review of the literature.

RATIONALE: Schwannomas involving the thyroid gland are very rare and only a few cases have been reported in the literature. However, previous reports did not distinguish between thyroid bed schwannomas and intrathyroidal schwannomas. Here, we report a thyroid bed schwannoma mimicking a malignant thyroid nodule and review the literature on thyroid bed schwannomas. PATIENT CONCERNS: A 33-year-old woman presented at our hospital with mild neck swelling. DIAGNOSIS: Thyroid ultrasound revealed a well-defined, oval-shaped, markedly hypoechoic solid nodule with echogenic foci suggesting macro- and microcalcifications in the left thyroid gland. The lesion was considered a "highly suspicious" intrathyroidal nodule, based on the guidelines for the assessment of thyroid nodules. Fine needle aspiration was performed twice, but the cytological results were nondiagnostic. INTERVENTIONS: Left thyroidectomy was performed, and schwannoma of the thyroid bed was confirmed on histopathologic analysis. OUTCOMES: The patient was in a stable condition after surgery, and the thyroid function test results were within the normal range. LESSONS: Diagnosis of a schwannoma of the thyroid bed is challenging because its incidence is extremely low, and it is often misdiagnosed as an intrathyroidal nodule on ultrasonography. Therefore, it is advisable to adopt a diagnostic strategy to perform additional core needle biopsy in cases of thyroid nodules with nondiagnostic fine needle aspiration results and to consider the location of the lesion more carefully to determine the suitable therapy.

Hybrid Composite of Silver Nanoparticle-Porous Silicon Microparticles as an Image-Guided Localization Agent for Computed Tomography Scan of the Lungs.

A hybrid composite of silver nanoparticles (AgNPs) and porous silicon microparticles (pSiMPs) was developed and applied for the computed tomography (CT) scanning of the lungs as an image-guided localization agent. We confirmed the grafting of AgNPs on oxidized pSiMPs template using various analytical equipment, including a scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The hybrid composite showed a high CT contrast intensity (>1000 HU) that enabled us to produce and view images of the lungs. In addition, it showed the ability to maintain a strong CT signal at the injected area of the rabbit's lungs, up to an hour, without spreading. The lack of toxicity and immune response indicated that the composite could be fully utilized as a new image-guided localization agent of CT scans for lung cancer surgery.

Sequential spinal and intracranial dural metastases in gastric adenocarcinoma: A case report.

Dural metastasis from primary gastric adenocarcinoma has been rarely reported, and its prognosis is very poor because it frequently leads to acute subdural hematoma. Here, we describe a case with sequential spinal and cranial dural metastases from gastric adenocarcinoma without subdural hematoma. A 43-year-old woman with gastric adenocarcinoma and well-controlled peritoneal carcinomatosis presented with back pain, right radiating leg pain, left facial palsy, and hearing loss. Magnetic resonance imaging of the spine and brain revealed dural masses at the lumbosacral junction with invasion to the L5 and S1 nerve roots and at the skull base with invasion to the internal auditory canal. She was treated with local radiotherapy, and her pain and neurologic symptoms improved after palliative radiotherapy. This is the first reported case of dural metastases of gastric adenocarcinoma of the spine and skull base but with a relatively indolent course and without subdural hematoma.

Usefulness of core needle biopsy for thyroid nodules with macrocalcifications: comparison with fine-needle aspiration.

BACKGROUND: This study was performed to determine the benefits of core needle biopsy (CNB), as compared with fine-needle aspiration (FNA), for the diagnosis of thyroid nodules with macrocalcifications. MATERIALS AND METHODS: The institutional review board approved this retrospective study, and informed consent was waived. From February 2010 to March 2012, the study included 147 thyroid nodules with macrocalcification of 145 consecutive patients who underwent simultaneous FNA and CNB for each nodule. Diagnostic accuracy and inconclusive diagnoses, including nondiagnostic reading and atypia of undetermined significance or follicular lesion of undetermined significance reading were compared among FNA, CNB, and a combination of FNA and CNB (FNA/CNB) using McNemar's test; the benefits of CNB were calculated. RESULTS: Compared to FNA, CNB and FNA/CNB showed fewer inconclusive diagnoses (FNA vs. CNB: 62/147 [42.2%] vs. 14/147 [9.5%], p<0.001; FNA vs. FNA/CNB: 62/147 [42.2%] vs. 14/147 [9.5%], p<0.001), resulting in the avoidance of repeat FNA or diagnostic surgery in 48 of 62 patients (77.4%, respectively in CNB and FNA/CNB) who would have undergone these procedures if only FNA was performed. Compared to FNA, FNA/CNB showed higher sensitivity and accuracy (sensitivity: 23/32 [71.9%] vs. 31/32 [96.9%], p=0.008; accuracy: 77/86 [89.5%] vs. 85/86 [98.8%], p=0.008), resulting in avoidance of delayed surgery in eight of nine patients (88.9%) with thyroid cancer in whom the surgery would have been missed if FNA only had been performed. CONCLUSION: In the workup of thyroid nodules with macrocalcification, compared with FNA alone, FNA/CNB decreases inconclusive diagnoses and increases sensitivity, thereby reducing repeated FNA procedures, diagnostic surgeries, and delayed therapeutic surgeries.

Long-term survival and differentiation of human neural stem cells in nonhuman primate brain with no immunosuppression.

Cellular fate of human neural stem cells (hNSCs) transplanted in the brain of nonhuman primates (NHPs) with no immunosuppression was determined at 22 and 24 months posttransplantation (PTx) regarding survival, differentiation, and tumorigenesis. Survival of hNSCs labeled with magnetic nanoparticles was successfully detected around injection sites in the brain at 22 months PTx by MRI. Histological examination of brain sections with H&E and Prussian blue staining at 24 months revealed that most of the grafted hNSCs were found located along the injection tract. Grafted hNSCs were found to differentiate into neurons at 24 months PTx. In addition, none of the grafted hNSCs were bromodeoxyuridine positive in the monkey brain, indicating that hNSCs did not replicate in the NHP brain and did not cause tumor formation. This study serves as a proof of principle and provides evidence that hNSCs transplanted in NHP brain could survive and differentiate into neurons in the absence of immunosuppression. It also serves as a preliminary study in our scheduled preclinical studies of hNSC transplantation in NHP stroke models.

Infratentorial and intraparenchymal subependymoma in the cerebellum: case report.

Subependymomas are rare benign tumors located in the ventricular system. Intraparenchymal subependymoma is extremely rare; only 6 cases have been reported, and all were located in the supratentorial region. We describe a case of infratentorial, intraparenchymal subependymoma in a 28-year-old man with intermittent headache. Imaging revealed a well-demarcated cystic and solid cerebellar mass near the fourth ventricle. The mass had a microcystic component and calcification without contrast enhancement. Complete surgical excision was performed, and histopathology confirmed a subependymoma.

True progression versus pseudoprogression in the treatment of glioblastomas: a comparison study of normalized cerebral blood volume and apparent diffusion coefficient by histogram analysis.

OBJECTIVE: The purpose of this study was to differentiate true progression from pseudoprogression of glioblastomas treated with concurrent chemoradiotherapy (CCRT) with temozolomide (TMZ) by using histogram analysis of apparent diffusion coefficient (ADC) and normalized cerebral blood volume (nCBV) maps. MATERIALS AND METHODS: Twenty patients with histopathologically proven glioblastoma who had received CCRT with TMZ underwent perfusion-weighted imaging and diffusion-weighted imaging (b = 0, 1000 sec/mm(2)). The corresponding nCBV and ADC maps for the newly visible, entirely enhancing lesions were calculated after the completion of CCRT with TMZ. Two observers independently measured the histogram parameters of the nCBV and ADC maps. The histogram parameters between the true progression group (n = 10) and the pseudoprogression group (n = 10) were compared by use of an unpaired Student's t test and subsequent multivariable stepwise logistic regression analysis to determine the best predictors for the differential diagnosis between the two groups. Receiver operating characteristic analysis was employed to determine the best cutoff values for the histogram parameters that proved to be significant predictors for differentiating true progression from pseudoprogression. Intraclass correlation coefficient was used to determine the level of inter-observer reliability for the histogram parameters. RESULTS: The 5th percentile value (C5) of the cumulative ADC histograms was a significant predictor for the differential diagnosis between true progression and pseudoprogression (p = 0.044 for observer 1; p = 0.011 for observer 2). Optimal cutoff values of 892 × 10(-6) mm(2)/sec for observer 1 and 907 × 10(-6) mm(2)/sec for observer 2 could help differentiate between the two groups with a sensitivity of 90% and 80%, respectively, a specificity of 90% and 80%, respectively, and an area under the curve of 0.880 and 0.840, respectively. There was no other significant differentiating parameter on the nCBV histograms. Inter-observer reliability was excellent or good for all histogram parameters (intraclass correlation coefficient range: 0.70-0.99). CONCLUSION: The C5 of the cumulative ADC histogram can be a promising parameter for the differentiation of true progression from pseudoprogression of newly visible, entirely enhancing lesions after CCRT with TMZ for glioblastomas.

Correlation of apparent diffusion coefficient values measured by diffusion MRI and MGMT promoter methylation semiquantitatively analyzed with MS-MLPA in patients with glioblastoma multiforme.

PURPOSE: To retrospectively determine whether the apparent diffusion coefficient (ADC) values correlate with O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation semiquantitatively analyzed by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) in patients with glioblastoma. MATERIALS AND METHODS: The study was approved by the Institutional Review Board and was Health Insurance Portability and Accountability Act (HIPAA) compliant. Newly diagnosed patients with glioblastoma (n = 26) were analyzed with an ADC histogram approach based on enhancing solid portion. The methylation status of MGMT promoter was assessed by methylation-specific polymerase chain reaction (MSP) and by MS-MLPA. MS-MLPA is a semiquantitative method that determines the methylation ratio. The Ki-67 labeling index was also analyzed. The mean and 5th percentile ADC values were correlated with MGMT promoter methylation status and Ki-67 labeling index using a linear regression model. Progression-free survival (PFS) was also correlated with the ADC values using Kaplan-Meier survival analysis. RESULTS: The mean methylation ratio was 0.21 ± 0.20. By MSP, there were 5 methylated and 21 unmethylated tumors. The mean ADC revealed a positive relationship with MGMT promoter methylation ratio (P = 0.015) and was also significantly different according to MSP-determined methylation status (P = 0.011). Median PFS was significantly related with methylation ratio (P = 0.017) and MSP-derived methylation status (P = 0.025). A positive relationship was demonstrated between PFS and the mean ADC value (P = 0.001). The 5th percentile ADC values showed a significant negative relationship with Ki-67 labeling index (P = 0.036). CONCLUSION: We found that ADC values were significantly correlated with PFS as well as with MGMT promoter methylation status. We believe that ADC values may merit further investigation as a noninvasive biomarker for predicting treatment response.

MR imaging findings of extraventricular neurocytoma: a series of ten patients confirmed by immunohistochemistry of IDH1 gene mutation.

BACKGROUND: Extraventricular neurocytomas (EVNs) are rare neuronal tumors included as neoplasms in the 2007 World Health Organization (WHO) classification of tumors of the CNS. Although a few case reports describing EVNs have been published, a systematic analysis of MR imaging findings of EVN has not been reported. Furthermore, imaging findings of IDH1 mutation-negative EVNs have not yet been reported. The aim of our study is to describe the MR imaging findings of IDH1 mutation-negative EVNs. METHODS: MR images of ten patients with pathologically confirmed IDH1 mutation-negative EVNs were retrospectively reviewed. Conventional MR imaging of ten EVNs were reviewed with emphasis on the location, signal intensities, patterns, and grades of enhancement as well as the presence/grade of peritumoral edema, intratumoral cyst, hemorrhage, and calcification. The study also reviewed the results of DWI (b = 1,000 s/mm(2), n = 7). RESULTS: Seven EVN cases were located in the cerebral hemisphere, and the remaining cases were in the cerebellum and thalamus. Of those in the cerebral hemisphere, five were cortically based tumors. The tumors showed no or mild peritumoral edema. Eight tumors were enhanced on the postcontrast T1WIs. An intratumoral cyst, hemorrhage, and calcification were detected in four, one, and two cases, respectively. On DWI, only one case showed a lower ADC value than the brain parenchyma. CONCLUSION: EVNs are usually cortically based infiltrative hemispheric tumors with contrast enhancement, higher ADC value, and sometimes small cystic component, but hardly show peritumoral edema or intratumoral hemorrhage. The differential diagnosis of these findings includes low-grade glioneuronal tumors and low-grade gliomas.

Diffusion-weighted MR imaging for the differentiation of true progression from pseudoprogression following concomitant radiotherapy with temozolomide in patients with newly diagnosed high-grade gliomas.

RATIONALE AND OBJECTIVES: The assessment of the therapeutic response of high-grade gliomas treated with concomitant chemoradiotherapy (CCRT) using temozolomide is difficult because of the frequent occurrence of early imaging changes that are indistinguishable from tumor progression, termed pseudoprogression. The purpose of this study was to determine whether diffusion-weighted imaging could be used to differentiate true progression and pseudoprogression. MATERIALS AND METHODS: Magnetic resonance images and diffusion-weighted images obtained within 2 months of CCRT completion in patients with high-grade gliomas were retrospectively reviewed. A total of 22 patients with increases in measurable enhancing regions were identified and classified into true progression and pseudoprogression groups on the basis of contrast-enhanced magnetic resonance images obtained 12 weeks after CCRT. Qualitative and quantitative analysis of diffusion-weighted images and apparent diffusion coefficient maps, respectively, was performed to discriminate true progression and pseudoprogression. Statistical analyses were performed using Fisher's exact test, unpaired t tests, and receiver-operating characteristic analysis. RESULTS: The true progression group showed a higher incidence of homogeneous or multifocal high signal intensity on diffusion-weighted images (seven of 10 patients [70%]), whereas rim high or no high signal intensity (10 of 12 [83%]) was observed in the pseudoprogression group (P = .027). True progression was defined by newly appearing or enlarged enhancing lesions with mean apparent diffusion coefficient values of 1200 × 10(-6) mm(2)/s inside the radiation field after CCRT; the sensitivity, specificity, and accuracy were 80% (eight of 10), 83.3% (10 of 12), and 81.2% (18 of 22), respectively. CONCLUSIONS: The assessment of diffusion-weighted images for patients with increases of measurable enhancing regions 2 months after CCRT completion is useful for differentiating true progression from pseudoprogression.

Ultrasonographic finding of internal jugular vein during anti-G straining maneuver: is it associated with gravity-induced loss of consciousness?

Gravity-induced loss of consciousness (G-LOC) is caused by loss of cerebral blood flow during high +Gz (head-to-foot inertial forces). The resistance of the jugular vein is a significant factor in decrease in cerebral blood flow. Ultrasonography of thoracic inlet veins, including internal jugular vein, is feasible to visualize the internal jugular vein and hemodynamic information. Anti-gravity straining maneuver (AGSM) was widely recognized as one of the important factors in preventing G-LOC. The purpose of this study was to evaluate the relationship between the ultrasonographic shape and size of internal jugular vein during AGSM and G-LOC. 47 trainee pilots who participated in human centrifuge education program were enrolled. They were all men, and their mean age was 23.9 +/- 1.38 years. Questionnaire sheets were used to collect information about well-being sensation, smoking, drinking, height, and weight. Using ultrasonography, we monitored shape and size of internal jugular vein during AGSM. After ultrasonographic examination, 47 subjects underwent human centrifuge on the same day. The protocol of human centrifuge training was maximal 6G with sustaining time of 30 s. G-LOC occurred to ten out of 47 subjects in human centrifuge. To find presumptive variable associated with G-LOC, we performed logistic regression analysis. Concave contour and smaller cross-sectional area of internal jugular vein during AGSM were associated with G-LOC.