Development and multi-institutional validation of an artificial intelligence-based diagnostic system for gastric biopsy.

To overcome the increasing burden on pathologists in diagnosing gastric biopsies, we developed an artificial intelligence-based system for the pathological diagnosis of gastric biopsies (AI-G), which is expected to work well in daily clinical practice in multiple institutes. The multistage semantic segmentation for pathology (MSP) method utilizes the distribution of feature values extracted from patches of whole-slide images (WSI) like pathologists' "low-power view" information of microscopy. The training dataset included WSIs of 4511 gastric biopsy tissues from 984 patients. In tissue-level validation, MSP AI-G showed better accuracy (91.0%) than that of conventional patch-based AI-G (PB AI-G) (89.8%). Importantly, MSP AI-G unanimously achieved higher accuracy rates (0.946 ± 0.023) than PB AI-G (0.861 ± 0.078) in tissue-level analysis, when applied to the cohorts of 10 different institutes (3450 samples of 1772 patients in all institutes, 198-555 samples of 143-206 patients in each institute). MSP AI-G had high diagnostic accuracy and robustness in multi-institutions. When pathologists selectively review specimens in which pathologist's diagnosis and AI prediction are discordant, the requirement of a secondary review process is significantly less compared with reviewing all specimens by another pathologist.

MADGAN: unsupervised medical anomaly detection GAN using multiple adjacent brain MRI slice reconstruction.

BACKGROUND: Unsupervised learning can discover various unseen abnormalities, relying on large-scale unannotated medical images of healthy subjects. Towards this, unsupervised methods reconstruct a 2D/3D single medical image to detect outliers either in the learned feature space or from high reconstruction loss. However, without considering continuity between multiple adjacent slices, they cannot directly discriminate diseases composed of the accumulation of subtle anatomical anomalies, such as Alzheimer's disease (AD). Moreover, no study has shown how unsupervised anomaly detection is associated with either disease stages, various (i.e., more than two types of) diseases, or multi-sequence magnetic resonance imaging (MRI) scans. RESULTS: We propose unsupervised medical anomaly detection generative adversarial network (MADGAN), a novel two-step method using GAN-based multiple adjacent brain MRI slice reconstruction to detect brain anomalies at different stages on multi-sequence structural MRI: (Reconstruction) Wasserstein loss with Gradient Penalty + 100 [Formula: see text] loss-trained on 3 healthy brain axial MRI slices to reconstruct the next 3 ones-reconstructs unseen healthy/abnormal scans; (Diagnosis) Average [Formula: see text] loss per scan discriminates them, comparing the ground truth/reconstructed slices. For training, we use two different datasets composed of 1133 healthy T1-weighted (T1) and 135 healthy contrast-enhanced T1 (T1c) brain MRI scans for detecting AD and brain metastases/various diseases, respectively. Our self-attention MADGAN can detect AD on T1 scans at a very early stage, mild cognitive impairment (MCI), with area under the curve (AUC) 0.727, and AD at a late stage with AUC 0.894, while detecting brain metastases on T1c scans with AUC 0.921. CONCLUSIONS: Similar to physicians' way of performing a diagnosis, using massive healthy training data, our first multiple MRI slice reconstruction approach, MADGAN, can reliably predict the next 3 slices from the previous 3 ones only for unseen healthy images. As the first unsupervised various disease diagnosis, MADGAN can reliably detect the accumulation of subtle anatomical anomalies and hyper-intense enhancing lesions, such as (especially late-stage) AD and brain metastases on multi-sequence MRI scans.

Use of Sugammadex in a Patient with Myotonic Dystrophy Undergoing Laparoscopic Cholecystectomy.

A 37-year-old female patient with myotonic dystrophy was scheduled for laparoscopic cholecystectomy for gall stone under general anesthesia with continuous propofol infusion. Rocuronium was administered with careful monitoring using TOF- Watch®, measuring train-of-four count (Tc), TOF ratio (Tr), and posttetanic count The total amount of rocuronium was 70 mg ; 0.6 mg .kg⁻1 for anesthetic induction and 0.3 mg .kg⁻1 when Tc exceeded 1. When the operation was completed, Tc was 4, Tr was uncountable and she showed reaction to calling her name. Then sugammadex 2 mg .kg⁻1, rapidly antagonized the neuromuscular block, such that the Tr recovered to 100% but tidal volume was 250 ml in 3 minutes. Additional dorsage of sugammadex, 2 mg .kg⁻1, was required for tidal volume to recover to 530 ml. After 20 minutes of first administration of sugammadex, we extubated the tracheal tube without respiratory depression. To avoid respiratory depression, we did not use postoperative opioids. Intraoperative transversus abdominis plane block and postoperative thoracic epidural block with ropivacaine were successful for postoperative pain relief.

[Anesthetic Management for a Patient with Stiff-person Syndrome].

The stiff-person syndrome (SPS) is a rare autoimmune neurologic disorder that affects the gamma-aminobutyric acid (GABA) mediated inhibitory network in the central nervous system with anti-glutamic acid decarboxylase (GAD) antibodies. SPS is characterized by muscle rigidity and painful episodic spasms in axial and lower limb muscles. This case report describes successful peri-operative management of a 61-year-old female (height, 158 cm; weight, 60 kg, ASA-PS 2) with her right upper arm fracture who was scheduled for open reduction and internal fixation. This patient had bulbar paralysis, dysphagia and muscle rigidity associated with a high titer of anti-GAD auto antibodies (2,800 U x ml(-1)). She was diagnosed as SPS and has been treated with predonisolone (30 mg x day(-1)) and diazepam (20 mg x day(-1)) for 1 year. Predonisolone (15 mg) and diazepam (30 mg) was given orally before induction of general anesthesia with propofol, remifentanil and rocuronium bromide. Posture change from supine to beach-chair position led to sudden drop in blood pressure to 38/25 mmHg, which recovered promptly by injecting intravenous ephedrine hydrochloride (28 mg) and hydrocortisone (100 mg). Postanesthetic course was uneventful without postoperative neurologic abnormalities.

Accuracy of lung nodule density on HRCT: analysis by PSF-based image simulation.

A computed tomography (CT) image simulation technique based on the point spread function (PSF) was applied to analyze the accuracy of CT-based clinical evaluations of lung nodule density. The PSF of the CT system was measured and used to perform the lung nodule image simulation. Then, the simulated image was resampled at intervals equal to the pixel size and the slice interval found in clinical high-resolution CT (HRCT) images. On those images, the nodule density was measured by placing a region of interest (ROI) commonly used for routine clinical practice, and comparing the measured value with the true value (a known density of object function used in the image simulation). It was quantitatively determined that the measured nodule density depended on the nodule diameter and the image reconstruction parameters (kernel and slice thickness). In addition, the measured density fluctuated, depending on the offset between the nodule center and the image voxel center. This fluctuation was reduced by decreasing the slice interval (i.e., with the use of overlapping reconstruction), leading to a stable density evaluation. Our proposed method of PSF-based image simulation accompanied with resampling enables a quantitative analysis of the accuracy of CT-based evaluations of lung nodule density. These results could potentially reveal clinical misreadings in diagnosis, and lead to more accurate and precise density evaluations. They would also be of value for determining the optimum scan and reconstruction parameters, such as image reconstruction kernels and slice thicknesses/intervals.

Image filtering as an alternative to the application of a different reconstruction kernel in CT imaging: feasibility study in lung cancer screening.

PURPOSE: While the acquisition of projection data in a computed tomography (CT) scanner is generally cqrried out once, the projection data is often removed from the system, making further reconstruction with a different reconstruction filter impossible. The reconstruction kernel is one of the most important parameters. To have access to all the reconstructions, either prior reconstructions with multiple kernels must be performed or the projection data must be stored. Each of these requirements would increase the burden on data archiving. This study aimed to design an effective method to achieve similar image quality using an image filtering technique in the image space, instead of a reconstruction filter in the projection space for CT imaging. The authors evaluated the clinical feasibility of the proposed method in lung cancer screening. METHODS: The proposed technique is essentially the same as common image filtering, which performs processing in the spatial-frequency domain with a filter function. However, the filter function was determined based on the quantitative analysis of the point spread functions (PSFs) measured in the system. The modulation transfer functions (MTFs) were derived from the PSFs, and the ratio of the MTFs was used as the filter function. Therefore, using an image reconstructed with a kernel, an image reconstructed with a different kernel was obtained by filtering, which used the ratio of the MTFs obtained for the two kernels. The performance of the method was evaluated by using routine clinical images obtained from CT screening for lung cancer in five subjects. RESULTS: Filtered images for all combinations of three types of reconstruction kernels ("smooth," "standard," and "sharp" kernels) showed good agreement with original reconstructed images regarded as the gold standard. On the filtered images, abnormal shadows suspected as being lung cancers were identical to those on the reconstructed images. The standard deviations (SDs) for the difference between filtered images and reconstructed images ranged from 1.9 to 23.5 Hounsfield units for all kernel combinations; these SDs were much smaller than the noise SDs in the reconstructed images. CONCLUSIONS: The proposed method has good performance and is clinically feasible in lung cancer screening. This method can be applied to images reconstructed on any scanner by measuring the PSFs in each system.

[Use of sugammadex in a patient with narrow angle glaucoma].

An 86-year-old woman was scheduled to receive fourth reconstructive surgery for femoral bone fracture under general anesthesia. She had been suspected with narrow angle glaucoma due to headache and bloodshot eyes during gastroscopy. During transfer to our hospital, she fell down and suffered from the right femoral neck fracture. The patient underwent femoral head replacement under spinal anesthesia. Later, she received surgeries twice uneventfully under spinal anesthesia; removal and re-implantation of the femoral bone head due to infection of the implanted head. Six months later, she fell down again and femoral bone was fractured during rehabilitation. Anesthesia was induced with propofol followed by rocuronium 0.9 mg x kg(-1) i.v. Anesthesia was maintained with propofol and remifentanil, and rocuronium was administered to maintain PTC of 10 or less. The surgery was completed in 150 minutes. At the end of surgery, a laryngeal mask was inserted and the tracheal tube was removed. TOF ratio recovered to 80% 8 minutes after sugammadex 2 mg kg(-1) i.v., and increased to 100% 3 minutes after additional 1 mg x kg(-1). Intraocular pressure stayed below 20 mmHg during the intervention. We could achieve full reversal of neuromuscular blockade and suppress increase in intraocular pressure with use of sugammadex.

Classification of large-scale image database of various skin diseases using deep learning.

PURPOSE: The purpose of this study was to develop a deep learning-based computer-aided diagnosis system for skin disease classification using photographic images of patients. The targets are 59 skin diseases, including localized and diffuse diseases captured by photographic cameras, resulting in highly diverse images in terms of the appearance of the diseases or photographic conditions. METHODS: ResNet-18 is used as a baseline model for classification and is reinforced by metric learning to boost generalization in classification by avoiding the overfitting of the training data and increasing the reliability of CADx for dermatologists. Patient-wise classification is performed by aggregating the inference vectors of all the input patient images. RESULTS: The experiment using 70,196 images of 13,038 patients demonstrated that classification accuracy was significantly improved by both metric learning and aggregation, resulting in patient accuracies of 0.579 for Top-1, 0.793 for Top-3, and 0.863 for Top-5. The McNemar test showed that the improvements achieved by the proposed method were statistically significant. CONCLUSION: This study presents a deep learning-based classification of 59 skin diseases using multiple photographic images of a patient. The experimental results demonstrated that the proposed classification reinforced by metric learning and aggregation of multiple input images was effective in the classification of patients with diverse skin diseases and imaging conditions.

Computer-aided volumetry of pulmonary nodules exhibiting ground-glass opacity at MDCT.

OBJECTIVE: The purpose of this study was to investigate the accuracy and reproducibility of results acquired with computer-aided volumetry software during MDCT of pulmonary nodules exhibiting ground-glass opacity. MATERIALS AND METHODS: To evaluate the accuracy of computer-aided volumetry software, we performed thin-section helical CT of a chest phantom that included simulated 3-, 5-, 8-, 10-, and 12-mm-diameter ground-glass opacity nodules with attenuation of -800, -630, and -450 HU. Three radiologists measured the volume of the nodules and calculated the relative volume measurement error, which was defined as follows: (measured nodule volume minus assumed nodule volume / assumed nodule volume) x 100. Two radiologists performed two independent measurements of 59 nodules in humans. Intraobserver and interobserver agreement was evaluated with Bland-Altman methods. RESULTS: The relative volume measurement error for simulated ground-glass opacity nodules measuring 3 mm ranged from 51.1% to 85.2% and for nodules measuring 5 mm or more in diameter ranged from -4.1% to 7.1%. In the clinical study, for intraobserver agreement, the 95% limits of agreement were -14.9% and -13.7% and -16.6% to 15.7% for observers A and B. For interobserver agreement, these values were -16.3% to 23.7% for nodules 8 mm in diameter or larger. CONCLUSION: With computer-aided volumetry of ground-glass opacity nodules, the relative volume measurement error was small for nodules 5 mm in diameter or larger. Intraobserver and interobserver agreement was relatively high for nodules 8 mm in diameter or larger.

[Propofol triggers a marked body temperature increase in a patient with fulminant malignant hyperthermia (MH) without inducing other symptoms of MH].

A 53-year-old woman who had experienced symptoms of fulminant malignant hyperthermia (MH) by sevoflurane a week before and her MH muscle biopsy revealing positive later, underwent the right hemicolectomy under total intravenous anesthesia with propofol and fentanyl. The patient's body temperature increased at a rate of 0.6 degree C per 15 min from 37.5 to 39.4 degrees C, but other symptoms of MH, such as tachycardia, arrhythmia, acidemia, and hypoxemia, were obviously slight in comparison with those induced by sevoflurane. The body temperature decreased after discontinuation of propofol and administration of dantrorene injection. When the patient received continuous propofol infusion for the purpose of sedation in the intensive care unit again, the body temperature gradually increased to 40 degrees C. However, it decreased to 37.8 degrees C after discontinuation of propofol and dantrorene injection again. It is well recognized that propofol is not a MH trigger, but it shoud be noted that some MH patients could experience a hypermetabolic state, such as hyperthermia, even by propofol.

[Spinal anesthesia in a patient with SMON disease].

We report a patient with subacute myelo-optico-neuropathy (SMON) in whom spinal anesthesia was employed to treat fracture of the femur neck. An 87-year-old woman was diagnosed as having SMON at the age of 45. The patient was admitted to our hospital with fracture of the femur neck. Aspiration pneumonia was also suspected with shadow in the right lung on the chest X-P The percutaneous oxygen saturation (Spo2) with room air was 77%. Spinal anesthesia with 5 mg of 0.5% hyperbaric bupivacaine and 20 mcg of fentanyl was performed at L3-4. The level of anesthesia was T4. During surgery, no severe pain in the lower limbs was observed. Three hours after the end of surgery, the level of anesthesia was T9. On the day after surgery, the extent of dysesthesia and reflex were similar to those before surgery. General anesthesia has been chosen in SMON patients, because there was a report of severe pain of the lower limbs after spinal anesthesia with dibucaine. In our patient, general anesthesia was considered inappropriate due to hypoxemia. We used a mixture of bupivacaine and fentanyl for spinal anesthesia, because the neurotoxicity of bupivacaine is weaker than that of dibucaine.

Determination of point spread function in computed tomography accompanied with verification.

A method for verifying the point spread function (PSF) measured by computed tomography has been previously reported [Med. Phys. 33, 2757-2764 (2006)]; however, this additional PSF verification following measurement is laborious. In the present study, the previously described verification method was expanded to PSF determination. First, an image was obtained by scanning a phantom. The image was then two-dimensionally deconvolved with the object function corresponding to the phantom structure, thus allowing the PSF to be obtained. Deconvolution is implemented simply by division of spatial frequencies (corresponding to inverse filtering), in which two parameters are used as adjustable ones. Second, an image was simulated by convolving the object function with the obtained PSF, and the simulated image was compared to the above-measured image of the phantom. The difference indicates the inaccuracy of the PSF obtained by deconvolution. As a criterion for evaluating the difference, the authors define the mean normalized standard deviation (SD) in the difference between simulated and measured images. The above two parameters for deconvolution can be adjusted by referring to the subsequent mean normalized SD (i.e., the PSF is determined so that the mean normalized SD is decreased). In this article, the parameters were varied in a fixed range with a constant increment to find the optimal parameter setting that minimizes the mean normalized SD. Using this method, PSF measurements were performed for various types of image reconstruction kernels (21 types) in four kinds of scanners. For the 16 types of kernels, the mean normalized SDs were less than 2.5%, indicating the accuracy of the determined PSFs. For the other five kernels, the mean normalized SDs ranged from 3.7% to 4.8%. This was because of a large amount of noise in the measured images, and the obtained PSFs would essentially be accurate. The method effectively determines the PSF, with an accompanying verification, after one scanning of a phantom.

[Specific gravity of bupivacaine with fentanyl influences bispectral index value during spinal anesthesia combined with fentanyl in patients undergoing cesarean section].

BACKGROUND: Spinal anesthesia combined with fentanyl sometimes induces sedation. We previously reported that the bispectral index (BIS) value during spinal anesthesia with isobaric bupivacaine is reduced with intrathecal fentanyl but not with intravenous or epidural fentanyl. The current study investigated whether the specific gravity of bupivacaine combined with intrathecal fentanyl in spinal anesthesia for cesarean section effected the BIS values. METHODS: Thirty-one partrients scheduled for cesarean section were allocated into two groups: 0.5% isobaric bupivacaine 2 ml plus fentanyl 20 microg (I group, n = 14) or 0.5% hyperbaric bupivacaine 2 ml plus fentanyl 20 microg (H group, n = 17). BIS values were recorded throughout the anesthesia. RESULTS: The lowest BIS values in the I group and in the H group were 77 +/- 13 and 87 +/- 6, respectively. The cumulative time for BIS values of or below 80 in the I group was longer than that in the H group. The number of BIS decreased cases, defined as the cases in which the BIS values continuously fell down to or below 80 for more than 10 minutes, in the I group was higher than in the H group. CONCLUSIONS: The BIS values in patients who received intrathecal isobaric bupivacaine with fentanyl were lower than those with intrathecal hyperbaric bupivacaine and fentanyl.

[Combined use of the airway scope and fiberoptic bronchoscopy for tracheal intubation in a patient with a large epiglottic cyst].

A 26-year-old man was scheduled for surgical extraction of a large epiglottic cyst. Mask ventilation was possible under propofol anesthesia without muscle relaxant. It was difficult to see the glottis using either a Macintosh laryngoscope or by fiberoptic bronchoscopy. When the AWS laryngoscope (Hoya, Tokyo Japan) with a part of the blade removed, was inserted orally, it became possible to see the glottis with a part of the epiglottic cyst. A reinforced tube was inserted nasally, and a fiberoptic bronchoscope was passed through the tube into the trachea. The tube was then passed over the fiberscope into the trachea. We believe that the Pentax AWS laryngoscope may lift the epiglottis and its cyst atraumatically, and may facilitate nasal fiberoptic intubation in a patient with a large epiglottic cyst.

The Laryngeal Mask Airway for exchange of a nasal for an orotracheal tube in a patient with Treacher Collins syndrome.

A new method of exchange of nasotracheal to orotracheal tube, using the Laryngeal Mask Airway (LMA), in a patient with difficult airway, is described. A 36-year-old woman with Treacher Collins syndrome was scheduled for a malar apatite cutting and a chin-level osteotomy. It was necessary to exchange a nasotracheal tube for an orotracheal tube during the operation. An LMA was inserted while the nasotracheal tube was left in place; a new tube was inserted in the LMA, then a fiberoptic laryngoscope (fiberscope) was inserted through these devices. The nasotracheal tube cuff was deflated, and the fiberscope was inserted into the trachea alongside the nasotracheal tube. The nasotracheal tube was removed, and the oral tube was then advanced into the trachea.

[Lethal air embolism after spray of tissue adhesive-fibrinogen and factor XIII aerosol during laparoscopic partial nephrectomy].

We report a case of lethal air embolism just after spray of adhesive-fibrinogen and factor XIII aerosol during laparoscopic surgery. A 76-year-old man underwent laparoscopic partial nephrectomy for the left renal cancer. After partial nephrectomy, adhesive-fibrinogen and factor XIII aerosol were sprayed to a bleeding region of the kidney. The blood pressure and the end-tidal carbon dioxide concentration suddenly decreased, followed by cardiac arrest. Trans-esophageal echocardiography and computed tomography after cardiopulmonary resuscitation confirmed multiple air embolism. The use of a spray aerosol during laparoscopic surgery may be associated with the risk of lethal air embolism.

Generation of realistic virtual nodules based on three-dimensional spatial resolution in lung computed tomography: A pilot phantom study.

PURPOSE: The aim of this feasibility study using phantoms was to propose a novel method for obtaining computer-generated realistic virtual nodules in lung computed tomography (CT). METHODS: In the proposed methodology, pulmonary nodule images obtained with a CT scanner are deconvolved with the point spread function (PSF) in the scan plane and slice sensitivity profile (SSP) measured for the scanner; the resultant images are referred to as nodule-like object functions. Next, by convolving the nodule-like object function with the PSF and SSP of another (target) scanner, the virtual nodule can be generated so that it has the characteristics of the spatial resolution of the target scanner. To validate the methodology, the authors applied physical nodules of 5-, 7- and 10-mm-diameter (uniform spheres) included in a commercial CT test phantom. The nodule-like object functions were calculated from the sphere images obtained with two scanners (Scanner A and Scanner B); these functions were referred to as nodule-like object functions A and B, respectively. From these, virtual nodules were generated based on the spatial resolution of another scanner (Scanner C). By investigating the agreement of the virtual nodules generated from the nodule-like object functions A and B, the equivalence of the nodule-like object functions obtained from different scanners could be assessed. In addition, these virtual nodules were compared with the real (true) sphere images obtained with Scanner C. As a practical validation, five types of laboratory-made physical nodules with various complicated shapes and heterogeneous densities, similar to real lesions, were used. The nodule-like object functions were calculated from the images of these laboratory-made nodules obtained with Scanner A. From them, virtual nodules were generated based on the spatial resolution of Scanner C and compared with the real images of laboratory-made nodules obtained with Scanner C. RESULTS: Good agreement of the virtual nodules generated from the nodule-like object functions A and B of the phantom spheres was found, suggesting the validity of the nodule-like object functions. The virtual nodules generated from the nodule-like object function A of the phantom spheres were similar to the real images obtained with Scanner C; the root mean square errors (RMSEs) between them were 10.8, 11.1, and 12.5 Hounsfield units (HU) for 5-, 7-, and 10-mm-diameter spheres, respectively. The equivalent results (RMSEs) using the nodule-like object function B were 15.9, 16.8, and 16.5 HU, respectively. These RMSEs were small considering the high contrast between the sphere density and background density (approximately 674 HU). The virtual nodules generated from the nodule-like object functions of the five laboratory-made nodules were similar to the real images obtained with Scanner C; the RMSEs between them ranged from 6.2 to 8.6 HU in five cases. CONCLUSIONS: The nodule-like object functions calculated from real nodule images would be effective to generate realistic virtual nodules. The proposed method would be feasible for generating virtual nodules that have the characteristics of the spatial resolution of the CT system used in each institution, allowing for site-specific nodule generation.

A method for evaluating the performance of computer-aided detection of pulmonary nodules in lung cancer CT screening: detection limit for nodule size and density.

OBJECTIVE: We propose the application of virtual nodules to evaluate the performance of computer-aided detection (CAD) of lung nodules in cancer screening using low-dose CT. METHODS: The virtual nodules were generated based on the spatial resolution measured for a CT system used in an institution providing cancer screening and were fused into clinical lung images obtained at that institution, allowing site specificity. First, we validated virtual nodules as an alternative to artificial nodules inserted into a phantom. In addition, we compared the results of CAD analysis between the real nodules (n = 6) and the corresponding virtual nodules. Subsequently, virtual nodules of various sizes and contrasts between nodule density and background density (ΔCT) were inserted into clinical images (n = 10) and submitted for CAD analysis. RESULTS: In the validation study, 46 of 48 virtual nodules had the same CAD results as artificial nodules (kappa coefficient = 0.913). Real nodules and the corresponding virtual nodules showed the same CAD results. The detection limits of the tested CAD system were determined in terms of size and density of peripheral lung nodules; we demonstrated that a nodule with a 5-mm diameter was detected when the nodule had a ΔCT > 220 HU. CONCLUSION: Virtual nodules are effective in evaluating CAD performance using site-specific scan/reconstruction conditions. Advances in knowledge: Virtual nodules can be an effective means of evaluating site-specific CAD performance. The methodology for guiding the detection limit for nodule size/density might be a useful evaluation strategy.

[Insertion of a laryngeal mask airway before removal of a nasotracheal tube in a patient after anterior spine surgery].

A 19-year-old man with cervical spondylosis (C4-C6) was scheduled for an anterior spine surgery. Anesthesia was induced with propofol and fentanyl, and nasotracheal intubation was performed without difficulty after vecuronium administration. Anesthesia was maintained with sevoflurane and nitrous oxide in oxygen supplemented with fentanyl. No complications were observed during the operation. After surgery, the patient's head and neck were stabilized by a halo-vest, and we attempted to minimize stress responses associated with tracheal extubation. While the patient was still deeply anesthetized, and the nasotracheal tube was in place, a laryngeal mask airway (LMA) was placed without difficulty. After confirming correct position of the LMA, the nasotracheal tube was removed without body movement or coughing. Removal of the LMA was safely performed after recovery of the patient's respiration and consciousness. We believe that the laryngeal mask airway is useful during emergence from anesthesia in the patient whose trachea is intubated nasally.