The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Liliana Goumnerova - One of the best experts on this subject based on the ideXlab platform.
-
telemetric intraventricular pressure measurements after third ventriculocisternostomy in a patient with noncommunicating hydrocephalus
Neurosurgery, 1997Co-Authors: David M Frim, Liliana GoumnerovaAbstract:OBJECTIVE: To examine and document intraventricular pressure (IVP) dynamics in an adult after endoscopic third ventriculocisternostomy performed as treatment for hydrocephalus associated with aqueductal stenosis. METHODS: A 30-year-old man who had undergone ventriculoperitoneal shunting at age 21 years for aqueductal stenosis caused by a tectal mass presented with symptoms and imaging studies consistent with shunt malfunction. He underwent urgent ventriculoscopic third ventricular ventriculocisternostomy, which resolved his symptomatology. The existing shunt was not revised. At the time of surgery, a catheter connected to an intracranial pressure TeleSensor device (Radionics, Burlington, MA) was inserted into the ventricular system. Postoperatively, the patient's recovery was assessed by IVP recordings. This system allowed us to record IVP in an awake patient with a functioning third ventriculocisternostomy. RESULTS: We observed an initial postoperative IVP of 17 cm H2O in the supine position, which decreased to 0 cm H2O at 90 degrees of head elevation. The IVP decreased during the first 48 hours postoperatively to 0 to 2 cm H2O when supine. By 1 week postoperatively, the patient's IVP had returned to a baseline of 15 to 17 cm H2O when supine, with a gradual decrease to 0 cm H2O at 30 degrees of head elevation. Three months postoperatively, the patient's IVP in the supine position was 8 cm H2O, with IVP decreasing to 0 cm H2O at 45 degrees of head elevation. Magnetic resonance (MR) imaging performed at that time revealed evidence of flow through the third ventriculocisternostomy. CONCLUSION: We conclude that after an initial period of adjustment, the IVP in this patient returned to an unremarkable baseline despite the novel fluid pathway into the prepontine cistern. This may represent maturation of the breach through the third ventricular floor or brain recovery from a period of high pressure. Also, the shape of the postural IVP curve closely resembled that observed in patients who are not hydrocephalic. These data represent the first documentation of the intraventricular pressure response to ventriculocisternostomy and suggest possible intracerebral responses to this alteration in cerebrospinal fluid flow.
-
telemetric intraventricular pressure measurements after third ventriculocisternostomy in a patient with noncommunicating hydrocephalus commentaries
Neurosurgery, 1997Co-Authors: David M Frim, Liliana Goumnerova, R J Maciunas, P J Kelly, P H ChapmanAbstract:OBJECTIVE: To examine and document intraventricular pressure (IVP) dynamics in an adult after endoscopic third ventriculocisternostomy performed as treatment for hydrocephalus associated with aqueductal stenosis. METHODS: A 30-year-old man who had undergone ventriculoperitoneal shunting at age 21 years for aqueductal stenosis caused by a tectal mass presented with symptoms and imaging studies consistent with shunt malfunction. He underwent urgent ventriculoscopic third ventricular ventriculocisternostomy, which resolved his symptomatology. The existing shunt was not revised. At the time of surgery, a catheter connected to an intracranial pressure TeleSensor device (Radionics, Burlington, MA) was inserted into the ventricular system. Postoperatively, the patient's recovery was assessed by IVP recordings. This system allowed us to record IVP in an awake patient with a functioning third ventriculocisternostomy. RESULTS: We observed an initial postoperative IVP of 17 cm H 2 O in the supine position, which decreased to 0 cm H 2 O at 90 degrees of head elevation. The IVP decreased during the first 48 hours postoperatively to 0 to 2 cm H 2 O when supine. By 1 week postoperatively, the patient's IVP had returned to a baseline of 15 to 17 cm H 2 O when supine, with a gradual decrease to 0 cm H 2 O at 30 degrees of head elevation. Three months postoperatively, the patient's IVP in the supine position was 8 cm H 2 O, with IVP decreasing to 0 cm H 2 O at 45 degrees of head elevation. Magnetic resonance (MR) imaging performed at that time revealed evidence of flow through the third ventriculocisternostomy. CONCLUSION: We conclude that after an initial period of adjustment, the IVP in this patient returned to an unremarkable baseline despite the novel fluid pathway into the prepontine cistern. This may represent maturation of the breach through the third ventricular floor or brain recovery from a period of high pressure. Also, the shape of the postural IVP curve closely resembled that observed in patients who are not hydrocephalic. These data represent the first documentation of the intraventricular pressure response to ventriculocisternostomy and suggest possible intracerebral responses to this alteration in cerebrospinal fluid flow.
M Heydaria - One of the best experts on this subject based on the ideXlab platform.
-
poster thur eve 73 dosimetric performance of Radionics mini mlc on elekta synergy s linear accelerator a monte carlo evaluation
Medical Physics, 2010Co-Authors: K A Lahroodi, M HeydariaAbstract:This work contributed new information of dosimetric evaluation of Radionics mini‐multileaf collimator (MMLC) attached on the head of an Elekta Synergy S linear accelerator using Monte Carlo simulations. The penumbrae, depth and lateral dose profiles of the Radionics MMLC for the 6 MV photon beams, were determined first time using the EGSnrc‐based Monte Carlo codes (BEAMnrc) verified by measurements. The Monte Carlo modelled MMLC has a maximum field size of 9.6 × 12 cm2 and 3.8 mm leaf thickness at the isocenter. Monte Carlo verification was carried out using CC13 Wellhofer ionization chamber (cavity volume = 0.13 cm3) and a Wellhofer water tank for measurements. Dosimetric parameters such as the penumbrae, percentage depth doses, the in‐plane and cross‐plane off‐axis dose profiles were measured and calculated for different field sizes and depths. Penumbra widths (80%−20%) for the reference field of 9.6 × 10.4 cm2 at the isocenter with a depth of 10 cm were 4.8 and 5.1 mm for the leaf‐sides and leaf‐ends, respectively. The corresponding values of penumbrae at depths of 1.5 and 5 cm were 3.6 and 4.2 mm for the leaf‐sides and 3.8 and 4.5 mm for the leaf‐ends. Dosimetric results based on our Monte Carlo model demonstrated excellent agreement to within 1% or 1 mm when compared to measurements. Our Monte Carlo model for the MMLC is expected to benefit the commissioning of the stereotactic radiosurgery planning for the small intracranial and extracranial lesions.
-
su ff t 182 dosimetric comparison of an elekta synergy s beam modulator Radionics mmlc using monte carlo simulations measurements
Medical Physics, 2006Co-Authors: N Esnaashari, M Heydaria, Mahmoud Allahverdi, David A JaffrayAbstract:Purpose: To compare dosimetric parameters of a new Elekta “Synergy S” dedicated stereotactic radiosurgeryMLC, namely the beam modulator (BM), with Radionics mini‐multileaf collimator (MMLC). Methods and Materials: The Beam Modulator maximum opening is 16cm×21cm and consists of 40 pairs of Tungsten leaves of 4mm thickness at the isocentre, with no back up jaws. Radionics MMLC has a maximum field size of 9.6cm×12cm and 3.75mm leaf thickness at the isocentre. Leakage and transmission, percentage depth doses (PDD) and dose profiles were measured and calculated for different field sizes and depths and for different source to surface distances (SSD). Kodak XV films, photon diode detector (diameter of active area 2mm), CC13 Wellhofer ion chamber (cavity volume 0.13 cm3) and Wellhofer water tank were used for measurements. BEAMnrc code was used for the Monte Carlo(MC) simulations. All the data are for a 6MV photon beam. Results: It is shown that the BM beams are slightly more energetic so that PDD at 10cm depth is 2% more for a 10.4cm × 9.6cm field, compared to Radionics MMLC. Dose profile results are generally comparable, except for the penumbra which is sharper for Radionics MMLC, especially in the leaf travel direction by up to 1.1 mm. Maximum and average leakage was 1.7 and 1.1 for BM and 1.2 and 0.9% for MMLC, respectively. MC calculation and measurement results for PDD and profiles agreed well to better than 1% and or 0.5mm. The uncertainty in simulation was less than 0.5%. Conclusion: Elekta “Synergy S” beam modulator and Radionics MMLC have successfully been modeled for the first time using the BEAMnrc MC simulations. The MC results showed an excellent agreement with the measurements. BM has a wider penumbra, mainly due to the larger isocentric distance and rounded leaf ends.
-
su ff t 128 clinical implementation of a new elekta dedicated stereotactic linac into Radionics treatment planning system
Medical Physics, 2006Co-Authors: M Heydaria, N Esnaashari, M Van Prooije, M IslamAbstract:Introduction: A new Elekta “Synergy S” dedicated stereotactic machine has been commissioned and clinically implemented. This linac has special features, including a kV cone beam CT(CBCT) and a multileaf collimator(MLC) system, termed as “Beam Modulator” (BM), with no back up jaws. Dosimetric parameters of the BM are compared with those of Radionics mini multileaf collimator (MMLC). The two MLC systems have different dosimetric parameters, chiefly due to different shapes, field sizes and isocentric distances. The effects of these differences on tumour dose coverage and sparing organs at risk (OAR) are evaluated. Methods and Materials: The leaf thickness and maximum field size at the isocentre are 4mm and 16×21cm for the BM and 3.75mm and 10×12cm for MMLC. The leaf‐bottom isocentric distances of the two systems are 45.2cm and 33cm, respectively. Radionics treatments planning (XKnife RT3.01) is used for planning comparison. Dose penumbras and percentage depth doses were measured using diode detector and XV2 films for different field sizes.CBCT doses were measured using an ion‐chamber and MOSFET. Two different clinical cases were chosen for the treatment planning comparison. RESULTS: MMLC dose penumbras (80–20%) at dmax for a 9.6×10.4cm field were 5.4mm and 5.6mm for the leaf sides and leaf ends, respectively and 5.8mm and 6.5mm for BM. As a result, Radionics MMLC has the advantage of better sparing of OARs. Also, Radionics MMLC delivered the prescribed doses using fewer segments and less number of monitor units by up to 20%. The CBCT dose to head phantom was in the range of 1.5 to 3.0 cGy per scan. Conclusion: In this work it is shown that the above MLC systems are overall clinically comparable, with Radionics MMLC marginally better sparing normal tissues. The Elekta BM however has the advantage of larger field size and better isocentric clearance.
David M Frim - One of the best experts on this subject based on the ideXlab platform.
-
telemetric intraventricular pressure measurements after third ventriculocisternostomy in a patient with noncommunicating hydrocephalus
Neurosurgery, 1997Co-Authors: David M Frim, Liliana GoumnerovaAbstract:OBJECTIVE: To examine and document intraventricular pressure (IVP) dynamics in an adult after endoscopic third ventriculocisternostomy performed as treatment for hydrocephalus associated with aqueductal stenosis. METHODS: A 30-year-old man who had undergone ventriculoperitoneal shunting at age 21 years for aqueductal stenosis caused by a tectal mass presented with symptoms and imaging studies consistent with shunt malfunction. He underwent urgent ventriculoscopic third ventricular ventriculocisternostomy, which resolved his symptomatology. The existing shunt was not revised. At the time of surgery, a catheter connected to an intracranial pressure TeleSensor device (Radionics, Burlington, MA) was inserted into the ventricular system. Postoperatively, the patient's recovery was assessed by IVP recordings. This system allowed us to record IVP in an awake patient with a functioning third ventriculocisternostomy. RESULTS: We observed an initial postoperative IVP of 17 cm H2O in the supine position, which decreased to 0 cm H2O at 90 degrees of head elevation. The IVP decreased during the first 48 hours postoperatively to 0 to 2 cm H2O when supine. By 1 week postoperatively, the patient's IVP had returned to a baseline of 15 to 17 cm H2O when supine, with a gradual decrease to 0 cm H2O at 30 degrees of head elevation. Three months postoperatively, the patient's IVP in the supine position was 8 cm H2O, with IVP decreasing to 0 cm H2O at 45 degrees of head elevation. Magnetic resonance (MR) imaging performed at that time revealed evidence of flow through the third ventriculocisternostomy. CONCLUSION: We conclude that after an initial period of adjustment, the IVP in this patient returned to an unremarkable baseline despite the novel fluid pathway into the prepontine cistern. This may represent maturation of the breach through the third ventricular floor or brain recovery from a period of high pressure. Also, the shape of the postural IVP curve closely resembled that observed in patients who are not hydrocephalic. These data represent the first documentation of the intraventricular pressure response to ventriculocisternostomy and suggest possible intracerebral responses to this alteration in cerebrospinal fluid flow.
-
telemetric intraventricular pressure measurements after third ventriculocisternostomy in a patient with noncommunicating hydrocephalus commentaries
Neurosurgery, 1997Co-Authors: David M Frim, Liliana Goumnerova, R J Maciunas, P J Kelly, P H ChapmanAbstract:OBJECTIVE: To examine and document intraventricular pressure (IVP) dynamics in an adult after endoscopic third ventriculocisternostomy performed as treatment for hydrocephalus associated with aqueductal stenosis. METHODS: A 30-year-old man who had undergone ventriculoperitoneal shunting at age 21 years for aqueductal stenosis caused by a tectal mass presented with symptoms and imaging studies consistent with shunt malfunction. He underwent urgent ventriculoscopic third ventricular ventriculocisternostomy, which resolved his symptomatology. The existing shunt was not revised. At the time of surgery, a catheter connected to an intracranial pressure TeleSensor device (Radionics, Burlington, MA) was inserted into the ventricular system. Postoperatively, the patient's recovery was assessed by IVP recordings. This system allowed us to record IVP in an awake patient with a functioning third ventriculocisternostomy. RESULTS: We observed an initial postoperative IVP of 17 cm H 2 O in the supine position, which decreased to 0 cm H 2 O at 90 degrees of head elevation. The IVP decreased during the first 48 hours postoperatively to 0 to 2 cm H 2 O when supine. By 1 week postoperatively, the patient's IVP had returned to a baseline of 15 to 17 cm H 2 O when supine, with a gradual decrease to 0 cm H 2 O at 30 degrees of head elevation. Three months postoperatively, the patient's IVP in the supine position was 8 cm H 2 O, with IVP decreasing to 0 cm H 2 O at 45 degrees of head elevation. Magnetic resonance (MR) imaging performed at that time revealed evidence of flow through the third ventriculocisternostomy. CONCLUSION: We conclude that after an initial period of adjustment, the IVP in this patient returned to an unremarkable baseline despite the novel fluid pathway into the prepontine cistern. This may represent maturation of the breach through the third ventricular floor or brain recovery from a period of high pressure. Also, the shape of the postural IVP curve closely resembled that observed in patients who are not hydrocephalic. These data represent the first documentation of the intraventricular pressure response to ventriculocisternostomy and suggest possible intracerebral responses to this alteration in cerebrospinal fluid flow.
Tipu Z Aziz - One of the best experts on this subject based on the ideXlab platform.
-
localisation of the subthalamic nucleus using Radionics image fusion and stereoplan combined with field potential recording a technical note
Stereotactic and Functional Neurosurgery, 2001Co-Authors: Xuguang Liu, J Rowe, Dipanka Nandi, Gail Hayward, Simo Parki, J F Stei, Tipu Z AzizAbstract:Subthalamic nucleus stimulation is an effective therapy for alleviating parkinsonian tremor, rigidity and bradykinesia. Although microelectrode recording is said to be essential for accurate targeting, this often prolongs the operation and the multiple recording tracts required may increase the incidence of complications, particularly haemorrhage. We describe a technique for implantation of deep brain electrodes in the subthalamic nucleus using MRI/CT fusion for anatomical localisation followed by bipolar recording of focal field potentials via the implanted stimulating electrode for neurophysiological confirmation of the stimulation site. The technique is effective, safe and requires much less time, and can be used as an alternative method to microelectrode recording.
-
use of the Radionics image fusion and stereoplan programs for target localization in functional neurosurgery
Journal of Clinical Neuroscience, 1998Co-Authors: Vakis Papanastassiou, Jeremy Rowe, Richard Sco, Pete A Silbu, L Davies, Tipu Z AzizAbstract:Abstract We describe the use of Radionics Image Fusion™ and Stereoplan™ in defining the target for thalamotomy and pallidotomy in functional surgery for parkinsonism and tremor. Using this to fuse and spatially correct magnetic resonance imaging (MRI) to computed tomography (CT) images our calculated targets were a mean of 0.6 ± 1.5 mm from the end target determined physiologically by stimulation. This is significantly better than the values of 2.6 ± 1.6 mm for thalamic targets and 7.1 ± 3.7 mm for pallidal targets using CT alone. As a consequence, determination of the target and the lesion making are routinely performed in one pass of the electrode allowing for faster, more accurate and, we believe, safer functional procedures.
Jie Tian - One of the best experts on this subject based on the ideXlab platform.
-
non invasive genotype prediction of chromosome 1p 19q co deletion by development and validation of an mri based radiomics signature in lower grade gliomas
Medical Imaging 2019: Computer-Aided Diagnosis, 2019Co-Authors: Yali Zang, Shuaitong Zhang, Dongsheng Gu, Jie Tian, Di Dong, Jiang Du, Chao Li, Hongyan Chen, Dabiao ZhouAbstract:To pre-operatively and non-invasively predict 1p/19q co-deletion in grade II and III (lower-grade) glioma based on a radiomics method using magnetic resonance imaging (MRI). We obtained 105 patients pathologically diagnosed with lower-grade glioma. We extracted 647 MRI-based features from T2-weighted images and selected discriminative features by lasso logistic regression approaches on the training cohort (n=69). Radiomics, clinical, and combined models were constructed separately to verify the predictive performance of the radiomics signature. The predictability of the three models were validated on a time-independent validation cohort (n = 36). Finally, 7 discriminative radiomic features were used constructed radiomics signature, which demonstrated satisfied performance on both the training and validation cohorts with AUCs of 0.822 and 0.731, respectively. Particularly, the combined model incorporating the radiomics signature and the clinic-radiological factors achieved the best discriminative capability with AUCs of 0.911 and 0.866 for training and validation cohorts, respectively.
-
magnetic resonance imaging based radiomics signature for the preoperative discrimination of stage i ii and iii iv head and neck squamous cell carcinoma
European Journal of Radiology, 2018Co-Authors: Jie Tian, Di Dong, Ying Yuan, Xiaoxia LiAbstract:Abstract Purpose This study aimed to investigate the predictive ability of magnetic resonance imaging (MRI) based radiomics signature for the preoperative staging in HNSCC. Methods This study involved127 consecutive patients (training cohort: n = 85; testing cohort, n = 42) with stage I–IV HNSCC. A total of 970 radiomics features were extracted from T2-weighted (T2W) (n = 485) and contrast-enhanced T1-weighted (ceT1W) (n = 485) MRI for each case. Radiomics signatures were constructed with least absolute shrinkage and selection operator (LASSO) logistic regression. Associations between radiomics signatures and HNSCC staging were explored. Areas under the receiver operating characteristic curve (AUC) and classification performance of radiomics signatures were determined and compared with those of the visual assessment. Results Ten features from T2W images, six from ceT1W images, and six from combined T2W and ceT1W images were selected by LASSO logistic regression. The three radiomics signatures of stage III-IV HNSCC were significantly higher than that for stage I-II in both cohorts (all P Conclusion Radiomics signature based on MRI could discriminate stage I-II from stage III-IV HNSCC, which may serve as a complementary tool for preoperative staging.
-
non invasive genotype prediction of chromosome 1p 19q co deletion by development and validation of an mri based radiomics signature in lower grade gliomas
Journal of Neuro-oncology, 2018Co-Authors: Yali Zang, Shuaitong Zhang, Mu Zhou, Dongsheng Gu, Olivier Gevaert, Di Dong, Jiang Du, Chao Li, Hongyan Chen, Jie TianAbstract:To perform radiomics analysis for non-invasively predicting chromosome 1p/19q co-deletion in World Health Organization grade II and III (lower-grade) gliomas. This retrospective study included 277 patients histopathologically diagnosed with lower-grade glioma. Clinical parameters were recorded for each patient. We performed a radiomics analysis by extracting 647 MRI-based features and applied the random forest algorithm to generate a radiomics signature for predicting 1p/19q co-deletion in the training cohort (n = 184). The clinical model consisted of pertinent clinical factors, and was built using a logistic regression algorithm. A combined model, incorporating both the radiomics signature and related clinical factors, was also constructed. The receiver operating characteristics curve was used to evaluate the predictive performance. We further validated the predictability of the three developed models using a time-independent validation cohort (n = 93). The radiomics signature was constructed as an independent predictor for differentiating 1p/19q co-deletion genotypes, which demonstrated superior performance on both the training and validation cohorts with areas under curve (AUCs) of 0.887 and 0.760, respectively. These results outperformed the clinical model (AUCs of 0.580 and 0.627 on training and validation cohorts). The AUCs of the combined model were 0.885 and 0.753 on training and validation cohorts, respectively, which indicated that clinical factors did not present additional improvement for the prediction. Our study highlighted that an MRI-based radiomics signature can effectively identify the 1p/19q co-deletion in histopathologically diagnosed lower-grade gliomas, thereby offering the potential to facilitate non-invasive molecular subtype prediction of gliomas.
-
preoperative and non invasive prediction of chromosome arm 1p 19q codeletion in oligodendroglial tumors using mri based radiomics
Journal of Clinical Oncology, 2018Co-Authors: Dongsheng Gu, Jie TianAbstract:2049Background: Oligodendroglial tumor (OT) is a main subtype of gliomas, carrying poor prognosis. Fortunately, part of OT patients with chromosome 1p/19q codeletion show favorable response to chem...
-
mr based radiomics signature in differentiating ocular adnexal lymphoma from idiopathic orbital inflammation
European Radiology, 2018Co-Authors: Chen Shen, Jie Tian, Zheng Li, Junfang XianAbstract:To assess the value of the MR-based radiomics signature in differentiating ocular adnexal lymphoma (OAL) and idiopathic orbital inflammation (IOI). One hundred fifty-seven patients with pathology-proven OAL (84 patients) and IOI (73 patients) were divided into primary and validation cohorts. Eight hundred six radiomics features were extracted from morphological MR images. The least absolute shrinkage and selection operator (LASSO) procedure and linear combination were used to select features and build radiomics signature for discriminating OAL from IOI. Discriminating performance was assessed by the area under the receiver-operating characteristic curve (AUC). The predictive results were compared with the assessment of radiologists by chi-square test. Five radiomics features were included in the radiomics signature, which differentiated OAL from IOI with an AUC of 0.74 and 0.73 in the primary and validation cohorts respectively. There was a significant difference between the classification results of the radiomics signature and those of a radiology resident (p 0.05). Radiomics features have the potential to differentiate OAL from IOI. • Clinical and imaging findings of OAL and IOI often overlap, which makes diagnosis difficult. • Radiomics features can potentially differentiate OAL from IOI non invasively. • The radiomics signature discriminates OAL from IOI at the same level as an experienced radiologist.
