ABSTRACT
Background@#To deliver therapeutics into the brain, it is imperative to overcome the issue of the blood-brain-barrier (BBB). One of the ways to circumvent the BBB is to administer therapeutics directly into the brain parenchyma. To enhance the treatment efficacy for chronic neurodegenerative disorders, repeated administration to the target location is required. However, this increases the number of operations that must be performed. In this study, we developed the IntraBrain Injector (IBI), a new implantable device to repeatedly deliver therapeutics into the brain parenchyma. @*Methods@#We designed and fabricated IBI with medical grade materials, and evaluated the efficacy and safety of IBI in 9 beagles. The trajectory of IBI to the hippocampus was simulated prior to surgery and the device was implanted using 3D-printed adaptor and surgical guides. Ferumoxytol-labeled mesenchymal stem cells (MSCs) were injected into the hippocampus via IBI, and magnetic resonance images were taken before and after the administration to analyze the accuracy of repeated injection. @*Results@#We compared the planned vs. insertion trajectory of IBI to the hippocampus.With a similarity of 0.990 ± 0.001 (mean ± standard deviation), precise targeting of IBI was confirmed by comparing planned vs. insertion trajectories of IBI. Multiple administrations of ferumoxytol-labeled MSCs into the hippocampus using IBI were both feasible and successful (success rate of 76.7%). Safety of initial IBI implantation, repeated administration of therapeutics, and long-term implantation have all been evaluated in this study. @*Conclusion@#Precise and repeated delivery of therapeutics into the brain parenchyma can be done without performing additional surgeries via IBI implantation.
ABSTRACT
Tumor localization in patients receiving neoadjuvant chemotherapy (NACT) is challenging because substantial therapeutic remission of the original tumor after NACT is often noted.Currently, there is no guidance device that allows for an accurate estimation of the resection range in breast-conserving surgery after NACT. To increase the accuracy of tumor resection, we used a 3-dimensional-printed breast surgical guide based on magnetic resonance imaging (MRI) in the supine position for a breast cancer patient who underwent breast-conserving surgery after NACT. Using this device, the breast tumor with apparent therapeutic changes after NACT on imaging was successfully removed with clear resection margins by identifying the original tumor site in the affected breast. Irrespective of whether the residual tumor area after NACT is well defined, it is possible to confirm and target the tumor area on pre-NACT MRI using this device.
ABSTRACT
Tumor localization in patients receiving neoadjuvant chemotherapy (NACT) is challenging because substantial therapeutic remission of the original tumor after NACT is often noted.Currently, there is no guidance device that allows for an accurate estimation of the resection range in breast-conserving surgery after NACT. To increase the accuracy of tumor resection, we used a 3-dimensional-printed breast surgical guide based on magnetic resonance imaging (MRI) in the supine position for a breast cancer patient who underwent breast-conserving surgery after NACT. Using this device, the breast tumor with apparent therapeutic changes after NACT on imaging was successfully removed with clear resection margins by identifying the original tumor site in the affected breast. Irrespective of whether the residual tumor area after NACT is well defined, it is possible to confirm and target the tumor area on pre-NACT MRI using this device.
ABSTRACT
The artificial neural network (ANN)–a machine learning technique inspired by the human neuronal synapse system–was introduced in the 1950s. However, the ANN was previously limited in its ability to solve actual problems, due to the vanishing gradient and overfitting problems with training of deep architecture, lack of computing power, and primarily the absence of sufficient data to train the computer system. Interest in this concept has lately resurfaced, due to the availability of big data, enhanced computing power with the current graphics processing units, and novel algorithms to train the deep neural network. Recent studies on this technology suggest its potentially to perform better than humans in some visual and auditory recognition tasks, which may portend its applications in medicine and healthcare, especially in medical imaging, in the foreseeable future. This review article offers perspectives on the history, development, and applications of deep learning technology, particularly regarding its applications in medical imaging.
Subject(s)
Humans , Artificial Intelligence , Computer Systems , Delivery of Health Care , Diagnostic Imaging , Machine Learning , Neurons , Precision Medicine , SynapsesABSTRACT
BACKGROUND AND PURPOSE: The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. METHODS: 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. RESULTS: A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). CONCLUSIONS: Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis.
Subject(s)
Humans , Basilar Artery , Constriction, Pathologic , Fluorescence , Hemodynamics , Infarction , Magnetic Resonance Angiography , Magnetic Resonance Imaging , Microtubules , Plaque, Atherosclerotic , Rheology , Silicon , SiliconesABSTRACT
BACKGROUND AND PURPOSE: The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. METHODS: 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. RESULTS: A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). CONCLUSIONS: Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis.
Subject(s)
Humans , Basilar Artery , Constriction, Pathologic , Fluorescence , Hemodynamics , Infarction , Magnetic Resonance Angiography , Magnetic Resonance Imaging , Microtubules , Plaque, Atherosclerotic , Rheology , Silicon , SiliconesABSTRACT
The advent of three-dimensional printing (3DP) technology has enabled the creation of a tangible and complex 3D object that goes beyond a simple 3D-shaded visualization on a flat monitor. Since the early 2000s, 3DP machines have been used only in hard tissue applications. Recently developed multi-materials for 3DP have been used extensively for a variety of medical applications, such as personalized surgical planning and guidance, customized implants, biomedical research, and preclinical education. In this review article, we discuss the 3D reconstruction process, touching on medical imaging, and various 3DP systems applicable to medicine. In addition, the 3DP medical applications using multi-materials are introduced, as well as our recent results.
Subject(s)
Humans , Biomedical Research , Computer-Aided Design , Diagnostic Imaging/instrumentation , Precision Medicine , Printing, Three-Dimensional , Prostheses and ImplantsABSTRACT
Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions.
Subject(s)
Biomarkers , Hemodynamics , Hydrodynamics , Magnetic Resonance ImagingABSTRACT
Background: Fine needle aspiration and biopsy(FNAB) has known the most accurate test(about 90%) in the preoperative evaluation of patients with a thyroid nodule. The false negative findings of thyroid cancer by FNAB are mainly due to the aspiration of cystic fluid in cystic degeneration of thyroid cancer and the ipossibility of differentiation between follicular adenoma and carcinoma by aspiration or FNAB because of the failure to evaluate the capsule invasion or angioinvasion of the tumor. Actually more than 80% of the nodules are found as benign nodules in aspiration or FNAB and the findings of follieular lesions are found about half of the samples tested, so limiting the cancer incidence in surgically resected samples up to 50% of the surgical resection. Sa reasonable guidelines to manage the benign nodules on aspiration or FNAB are needed which can select the maligna~nt nodules with false negative findings on aspiration or FNAB. We tried to evaluate whether the thyroxine suppression therapy can increase the malignancy rates on thyroidectomy, Methods: We treated the benign thyroid nodules in FNAB with thyroxine for 1 year and cornpared the nodule volume change before and after treatment (every 6 month) with ultrasonogram. We performed thyroidectomy on 1~7 thyroid nodules wbich showed less than 50% decrease of nodule volume after 1 year of thyroxine suppression therapy. Results: The results were as follows. 1) Of all 17 patients, surgical resection revealed malignant thyroid nodule(Group I) in 10 cases (58.82%, papillary cancer. 6 cases, follicular cancer: 4 cases) and benign thyroid nodule(Group II) in 7 cases(41.18%, follicular adenoma: 4 cases, adenomatous goiter: 3 cases). 2) Between group I and II, there was no significant differences in serum T, T and TSH levels before and after thyroxine suppression therapy. Also, there were no significant difference in TSH suppression % between group I and group II(5.60+5.39%, 14.64+11.48%, respectively). 3) Thyroid nodule volume decrease percent before and after thyroxi~ne therapy showed no significant difference between group I and group II (124.80+54.18% vs 159.42+79.82%, p>0.05). Conclusion: Our data suggested that the benign thyroid nodules on aspiration or FNAB which were not suppressed in volume after thyroixine therapy revealed more than 50% incidence of malignancy on surgical resection, so these nodules were highly reeommended to surgical exploration.