Monte Carlo calculations and experimental measurements of the TG-43U1-recommended dosimetric parameters of 125I (Model IR-Seed2) brachytherapy source.

A new design of 125I (Model IR-Seed2) brachytherapy source has been manufactured recently at the Applied Radiation Research School, Nuclear Science and Technology Research Institute in Iran. The source consists of six resin beads (0.5 mm diameter) that are sealed in a cylindrical titanium capsule of 0.7 mm internal and 0.8 mm external diameters. This work aims to evaluate the dosimetric parameters of the newly designed 125I source using experimental measurements and Monte Carlo (MC) simulations. Dosimetric characteristics (dose rate constant, radial dose function, and 2D and 1D anisotropy functions) of the IR-Seed2 were determined using experimental measurements and MC simulations following the recommendations by the Task Group 43 (TG-43U1) report of the American Association of Physicists in Medicine (AAPM). MC simulations were performed using the MCNP5 code in water and Plexiglas, and experimental measurements were carried out using thermoluminescent dosimeters (TLD-GR207A) in Plexiglas phantoms. The measured dose to water in Plexiglas data were used for verification of the accuracy of the source and phantom geometry in the Monte Carlo simulations. The final MC simulated data to water in water were recommended for clinical applications. The MC calculated dose rate constant (Λ) of the IR-Seed2 125I seed in water was found to be 0.992 ± 0.025 cGy h-1U-1. Additionally, its radial dose function by line and point source approximations, gL(r) and gp(r), calculated for distances from 0.1 cm to 7 cm. The values of gL(r) at radial distances from 0.5 cm to 5 cm were measured in a Plexiglas phantom to be between 1.212 and 0.413. The calculated and measured of values for 2D anisotropy function, F(r, θ), were obtained for the radial distances ranging from 1.5 cm to 5 cm and angular range of 0°-90° in a Plexiglas phantom. Also, the 2D anisotropy function was calculated in water for the clinical application. The results of these investigations show that the uncertainty of the experimental data is within ± 7% between the measured and simulated data in Plexiglas. Based on these results, the MC-simulated dosimetric parameters of the new 125I source model in water are presented for its clinical applications in brachytherapy treatments.

Artificial neural networks in neurosurgery.

Artificial neural networks (ANNs) effectively analyze non-linear data sets. The aimed was A review of the relevant published articles that focused on the application of ANNs as a tool for assisting clinical decision-making in neurosurgery. A literature review of all full publications in English biomedical journals (1993-2013) was undertaken. The strategy included a combination of key words 'artificial neural networks', 'prognostic', 'brain', 'tumor tracking', 'head', 'tumor', 'spine', 'classification' and 'back pain' in the title and abstract of the manuscripts using the PubMed search engine. The major findings are summarized, with a focus on the application of ANNs for diagnostic and prognostic purposes. Finally, the future of ANNs in neurosurgery is explored. A total of 1093 citations were identified and screened. In all, 57 citations were found to be relevant. Of these, 50 articles were eligible for inclusion in this review. The synthesis of the data showed several applications of ANN in neurosurgery, including: (1) diagnosis and assessment of disease progression in low back pain, brain tumours and primary epilepsy; (2) enhancing clinically relevant information extraction from radiographic images, intracranial pressure processing, low back pain and real-time tumour tracking; (3) outcome prediction in epilepsy, brain metastases, lumbar spinal stenosis, lumbar disc herniation, childhood hydrocephalus, trauma mortality, and the occurrence of symptomatic cerebral vasospasm in patients with aneurysmal subarachnoid haemorrhage; (4) the use in the biomechanical assessments of spinal disease. ANNs can be effectively employed for diagnosis, prognosis and outcome prediction in neurosurgery.

Use of artificial neural networks to predict recurrent lumbar disk herniation.

BACKGROUND: The aim of this study was to develop an artificial neural network (ANN) model to predict recurrent lumbar disk herniation (LDH). METHODS: An ANN model and a logistic regression model were used to predict recurrent LDH. The age, sex, duration of symptoms, smoking status, recurrent LDH, level of herniation, type of herniation, sports activity; occupational lifting, occupational driving, duration of symptoms, visual analog scale (VAS), the Zung Depression Scale (ZDS), and the Japanese Orthopaedic Association (JOA) Score, were determined as the input variables for the established ANN model. The Macnab classification, VAS, and JOA were used for outcome assessment. ANNs on data from LDH patients, who underwent surgery, were trained to predict LDH using several input variables. The patients were divided into a recurrent LDH group (R group) and a primary LDH group (P group). Sensitivity analysis was applied to identify the relevant variables. The receiver-operating characteristic curve, accuracy rate of predicting, and Hosmer-Lemeshow statistics were considered for evaluating the 2 models. RESULTS: A total of 402 patients were categorized into training, testing, and validation data sets consisting of 201, 101, and 100 cases, respectively. The recurrence rate was 8.7%, and the median time to recurrence was 26.2 months (SD=4 mo). The VAS of leg/back pain and JOA were improved at 1-year follow-up (P<0.05) and no significant difference was observed between the 2 groups. Surgical successful outcome was categorized as: excellent, 31.1%; good, 44.3%; fair, 18.9%; and poor, 5.7% at 1-year follow-up. Compared with the logistic regression model, the ANN model was associated with superior results: accuracy rate, 94.1%; Hosmer-Lemeshow statistic, 40.2%; and area under the curve, 0.83% of patients. CONCLUSION: The findings show that an ANNs can be used to predict the diagnostic statues of recurrent and nonrecurrent group of LDH patients before the first or index microdiscectomy.

A validation study of the Iranian version of STarT Back Screening Tool (SBST) in lumbar central canal stenosis patients.

BACKGROUND: This study aimed to translate and validate the STarT Back Screening Tool (SBST) in Iran. METHODS: This was a prospective clinical validation study. The translation and cross-cultural adaptation of the original questionnaire was performed, and a total of 269 patients with lumbar central canal stenosis were asked to respond to the questionnaire at their first visits. Patients also were asked to complete the Oswestry Disability Index (ODI). Reliability was assessed by internal consistency using the Cronbach's alpha coefficient. Validity was evaluated by performing convergent validity and responsiveness to change. RESULTS: Mean patient age was 58.6 [standard deviation (SD) = 10.9] years; 56.5 % were women. According to patients' imaging, they were diagnosed as grade 1 (n = 86), grade 2 (n = 107), and grade 3 (n = 76). In general, the SBST showed good psychometric properties. Cronbach's alpha coefficient for overall scale (Q1-Q9) and psychosocial subscale (Q5-Q9) was 0.82 and 0.79, respectively. The ODI correlated strongly with overall SBST scores, lending support to its good convergent validity (r = 0.81; P < 0.001). Responsiveness to change also indicated desirable results. CONCLUSION: In general, the Iranian version of the SBST performed well, and findings suggest that it is a reliable and valid measure for screening low back pain in patients with lumbar central canal stenosis in primary care settings.

An outcome measure of functionality and quality of life in Iranian women with osteoporotic vertebral fractures: a validation study of the QUALEFFO-41.

BACKGROUND: Osteoporosis is a very common disease and often results in vertebral fractures. The Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO-41) is a tool to measure health-related quality of life in these patients. This study aimed to cross-culturally translate and validate the QUALEFFO-41 in Iran. METHODS: This was a prospective clinical validation study. A forward-backward procedure was used to translate the questionnaire from English into Persian. The translation and cross-cultural adaptation were made in accordance with published guidelines. Patients were divided into two study groups according to the World Health Organization criteria: those with at least one vertebral fracture who had undergone surgery and those with osteoporosis and no fractures as a control group. All of the participants were assessed by both the QUALEFFO-41 and SF-36. The surgery group was asked to respond to the QUALEFFO-41 at two points in time: the pre- and postoperative assessments (6-month follow-up). To test reliability, the internal consistency was evaluated using Cronbach's alpha coefficient. Validity was evaluated by assessing convergent validity between the QUALEFFO-41 and SF-36 and item-scale correlations and discriminatory ability. Internal responsiveness of the QUALEFFO-41 to the clinical intervention (surgery) also was evaluated comparing patients' pre- and postoperative scores. RESULTS: A total of 149 patients completed the questionnaire: 48 surgical patients and 101 as a control group. At the pre- and postoperative assessments, the QUALEFFO-41 showed adequate internal consistency in all domains (Cronbach's alpha of 0.71 to 0.81). Additionally, the correlation of each item with its hypothesized domain on the QUALEFFO-41 indicated acceptable results, suggesting that the items had a substantial relationship with their own domains. Further analysis also indicated that the questionnaire was responsive to change (P < 0.0001). Significant correlations existed between scores of similar subscales of the QUALEFFO-41 and SF-36 (P < 0.001). CONCLUSIONS: The findings show that the Iranian version of the QUALEFFO-41 is a reliable and valid measure of functionality and quality-of-life evaluation among patients with osteoporotic vertebral fractures.

The Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) for low back disorders: a validation study from Iran.

BACKGROUND: Lumbar disc hernia (LDH) and lumbar spinal stenosis (LSS) are the most common diagnoses of low back and leg pain symptoms. The Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) is a measure of health-related quality of life in these patients. This study aimed to cross-culturally translate and validate the JOABPEQ in Iran. METHODS: This was a prospective clinical validation study. The translation and cross-cultural adaptation of the original questionnaire was performed in accordance with published guidelines. A total of 103 patients with LDH or LSS were asked to respond to the questionnaire at two points in time: pre- and postoperative assessments (6 months follow-up). To test reliability, the internal consistency was assessed by Cronbach's alpha coefficient, and validity was assessed using convergent validity. Responsiveness to change was also assessed comparing patients' pre- and postoperative scores. RESULTS: The Cronbach's alpha coefficients for the JOABPEQ at pre- and postoperative assessments ranged from 0.71 to 0.81, indicating a good internal consistency for the questionnaire. In addition, the correlation of each item with its hypothesized subscale of the JOABPEQ showed satisfactory results, suggesting that the items had a substantial association with the subscale representing the concept. Further analysis also indicated that the questionnaire was responsive to change (P < 0.0001). CONCLUSIONS: In general, the Iranian version of JOABPEQ performed well, and the findings suggest that it is a reliable and valid measure of back pain evaluation among LDH and LCS patients.

Computed tomography-guided stereotactic biopsy of intracranial lesions in pediatric patients.

PURPOSE: The primary objective of this study was to report the results of author's 18-year experience of diagnostic stereotactic biopsy procedures in children with intracranial lesions. METHODS AND MATERIALS: A retrospective analysis was conducted on stereotactic procedures performed on children with brain tumor between 1989 and 2007. RESULTS: Stereotactic biopsy of intracranial tumors was performed in 172 children (69 girls, and 103 boys) with the mean age of 9.17 ± 3.66 years at the time of diagnosis. The most frequent anatomical location of lesions was brainstem (45.9%). Glioma was the most common diagnosis, represented in 90.7% of patients (156 patients). Other diagnosed tumors (4.7%) were classified as metastatic (1.7%), lymphomas (1.2%), oligodendroglioma (0.6%), craniopharyngioma (0.6%), and pineocytoma (0.6%). Nonneoplastic lesions were revealed in 4.7% of patients. CONCLUSION: The most frequent brain pathology of children is glioma, but the incidence of brain lesions other than gliomas and the frequency of brain lesions in the inoperable areas are compelling reasons to establish tissue diagnosis.

Use of artificial neural networks to predict the probability of developing new cerebral metastases after radiosurgery alone.

BACKGROUND: The present study aimed to predict the probability of developing new cerebral metastases after Gamma Knife radiosurgery (GKR) alone in patients with 1-3 brain metastases by artificial neural network (ANN) model. METHODS: AAN and other methods were used. The AAN has been investigated in comparison of other models of analysis, including the logistic regression (LR) and the recently introduced Huttenlocher method. Patients were divided into a distant brain failure (DBF) or a distant brain control (DBC) within 6 months of follow-up. Eleven factors were determined as the input parameters for the established ANN and were trained to predict of DBF. Sensitivity analysis was performed. The ROC curve, accuracy rate, and Hosmer-Lemeshow (H-L) tests were used to assess the three different prediction methods. RESULTS: A total of 192 patients were categorized into the training (N.=96), testing (N.=48), and validation (N.=48) data sets in ANN. DBC rate was 60.4; based on the Huttenlocher classification method, it was 40.7% in Group I, 49.2% in Group II, and 88.1% in Group III. The number of cerebral metastases, primary tumor type, extra-cerebral metastases and recursive partitioning analysis (RPA) were the most important variables indicated by the ANN analysis. Compared to the other two methods, ANN model was associated to superior results: accuracy rate, 95.3%; H-L statistic, 40.9%; and AUC, 0. 0.88%. CONCLUSIONS: The ANNs can be used to effectively help for predicting DBF in patients with 1-3 brain metastasis treated with GKR alone.

Management of cystic craniopharyngiomas with intracavitary irradiation with 32P.

BACKGROUND: Cystic craniopharyngiomas are the most frequent intracranial neoplasm of nonglial origin in children. Follow-up data were analyzed to assess the value of intracavitary irradiation with stereotactically applied 32P radioisotopes for the treatment of patients with craniopharyngioma cysts admitted to Shohada Tajrish Hospital, Tehran, Iran, between 1998 and 2005. METHODS: Patients with predominantly cystic craniopharyngiomas, who underwent stereotactic intracavitary irradiation, were followed for tumor response and complications. Beta-emitting 32P isotopes were injected into cysts using a computed tomography-guided and computer-assisted three-dimensional stereotactic treatment planning and application system. The cumulative dose to the inner surface of the cyst wall was 250 Gy. RESULTS: Twenty-two (12 females and 10 males) patients with a mean+/-SD age of 14.0+/-6.6 (range: six to 35) years were studied. The tumor response rate gained with 32P-labeled chromic phosphate was 73% (16 of 22 cysts). The mean+/-SD survival after intracavitary irradiation was 25.4+/-6.8 (95% CI: 12.0 - 38.7) months. CONCLUSION: Intracavitary irradiation using 32P is highly effective in the treatment of cystic craniopharyngiomas. In patients with solitary cyst treated exclusively with this method, it has been the only necessary therapy over a long period. It seems reasonable to recommend intracavitary irradiation as the initial treatment for selected patients and as palliative therapy in those with recurrence.

Brain metastases in patients with diagnosed versus undiagnosed primary tumor.

OBJECTIVES: To propose a diagnostic work-up specifically tailored to the undiagnosed primary (UDP) tumor patients. METHODS: To investigate the distribution of primary tumors and presenting symptoms in UDP versus diagnosed primary (DP) patients, 50 consecutive patients with diagnosis of brain metastasis in Shohada Hospital, Tehran, Iran from January 2001 to December 2005 were included in this study. Univariate analyses were performed to assess the difference of various variables between DP and UDP patients. RESULTS: The UDP patients represented 46% of all. Aphasia was significantly more common in the UDP group (p=0.0008) and ataxia in the DP group (p=0.04). The source of the metastases proved to be different between the 2 groups of interest (p=0.0006). The lung was the most frequent primary site in both groups. Among all UDP patients, a primary tumor in a location other than the lung was only found in 17% of patients. This study validated the hypothesis that the distribution of primary tumors differs between DP and UDP patients. CONCLUSION: If lung investigation fails to disclose the location of primary tumor, the patient is unlikely to benefit from extensive paraclinical investigation. In such a situation, a neurosurgical procedure should be considered the most appropriate second step to be taken.

Evaluation of Bremsstrahlung radiation dose in stereotactically radiocolloid therapy of cystic craniopharyngioma tumors with 32P radio-colloid.

Over 90% of craniopharyngeal brain tumors are cystic, which enables the injection of beta emitters such as phosphorus-32 (32P) radio-colloid into cysts for their treatment. The aim of this study was to evaluate the clinical and theoretical modelling of Bremsstrahlung radiation dose resulting from stereotactic radio-colloid therapy of cystic craniopharyngioma tumors with 32P. 32P radio-colloid with appropriate activity concentration was injected to a head phantom, and then the Bremsstrahlung radiation spectrum and planar images were obtained using a gamma camera. Both phantom and gamma camera were simulated using MCNPX code, and the results were compared with practical results. Bremsstrahlung radiation spectrum was measured using a handheld gamma spectrometer for two patients treated with stereotactic radio-colloid therapy with 32P in different positions and compared to Monte Carlo simulation. Results of counting and determining sensitivity coefficients in the air and the attenuating environment were obtained. Also, comparing the counting sensitivity from practical and simulation methods indicated the agreement of the data between the two methods. Comparison of the spectra from different positions around patient's head indicated the ability to use this detector to quantify the activity in the operating room. Selection of the spectrum is important in Bremsstrahlung radiation imaging. We can take advantage of spectrometry measurement using gamma camera, handheld gamma spectrometer for patient, and theoretical modeling with Monte Carlo code to evaluate radiopharmaceutical distribution, leakage, as well as estimate activity and predict therapeutic effects in other adjacent structures and ultimately optimize radio-colloid therapy in cystic craniopharyngeal patients.

Cut-off Value for Body Mass Index in Predicting Surgical Success in Patients with Lumbar Spinal Canal Stenosis.

STUDY DESIGN: Case-control. PURPOSE: To determine optimal cut-off value for body mass index (BMI) in predicting surgical success in patients with lumbar spinal canal stenosis (LSCS). OVERVIEW OF LITERATURE: BMI is an essential variable in the assessment of patients with LSCS. METHODS: We conducted a prospective study with obese and non-obese LSCS surgical patients and analyzed data on age, sex, duration of symptoms, walking distance, morphologic grade of stenosis, BMI, postoperative complications, and functional disability. Obesity was defined as BMI of ≥30 kg/m2. Patients completed the Oswestry Disability Index (ODI) questionnaire before surgery and 2 years after surgery. Surgical success was defined as ≥30% improvement from the baseline ODI score. Receiver operating characteristic (ROC) analysis was used to estimate the optimal cut-off values of BMI to predict surgical success. In addition, correlation was assessed between BMI and stenosis grade based on morphology as defined by Schizas and colleague in total, 189 patients were eligible to enter the study. RESULTS: Mean age of patients was 61.5±9.6 years. Mean follow-up was 36±12 months. Most patients (88.4%) were classified with grades C (severe stenosis) and D (extreme stenosis). Post-surgical success was 85.7% at the 2-year follow-up. A weak correlation was observed between morphologic grade of stenosis and BMI. Rates of postoperative complications were similar between patients who were obese and those who were non-obese. Both cohorts had similar degree of improvement in the ODI at the 2-year followup. However, patients who were non-obese presented significantly higher surgical success than those who were obese. In ROC curve analysis, a cut-off value of ≤29.1 kg/m2 for BMI in patients with LSCS was suggestive of surgical success, with 81.1% sensitivity and 82.2% specificity (area under the curve, 0.857; 95% confidence interval, 0.788-0.927). CONCLUSION: This study showed that the BMI can be considered a parameter for predicting surgical success in patients with LSCS and can be useful in clinical practice.

Bilateral traumatic hypoglossal nerve transection in a blast injury.

BACKGROUND: The hypoglossal nerve supplies motor function to the tongue. CASE DESCRIPTION: A 21-year-old man was injured in a blast injury to his mandible, resulting in severe maxillofacial hemorrhaging. Irreversible injury was evident from lack of improvement to tongue; patient underwent transplantation by end-to-end coaptation of right injured nerve 6 months after injury, with subsequent repair to left nerve 2 months later. At 11-year follow up, there was acceptable force and normal motor activity. Only speech, mastication, and swallowing did not return to normal despite prolonged physiotherapy. CONCLUSION: In hypoglossal nerve injury, the proximity of the injury site to the primary muscle and, therefore, the short time required for the nerve fibers to repair toward the muscle are expected to predict an excellent outcome after transplantation. However, this is not usually the case, as in our patient.

Dosimetry of (32)P radiocolloid for treatment of cystic craniopharyngioma.

In Tajrish Shohada Hospital, patients with either cystic craniopharyngiomas or cystic astrocytomas have been treated with (32)P radiocolloid by stereotactic procedure. The total activity was prescribed for delivery dose between 200 and 300 Gy to the cyst wall thicknesses of 1-3mm. In this project, MD-55-2 radiochromic film was utilized to determine the dose distribution around the source. The film dosimetry data were compared with Monte Carlo simulated values calculated with MCNP4C code. In addition, the clinical and dosimetric factors such as the cyst volume, and method of radiocolloid injection were evaluated. The required activity and distribution of radial dose in and out of cyst wall have been investigated.

Cerebral lymphoma: clinical and radiological findings in 90 cases.

BACKGROUND: Cerebral lymphoma is a rare non-Hodgkin's lymphoma, which involves the brain primarily or after systemic involvement. Because of its infiltrating nature and its sensitivity to radio- and chemotherapy, surgical removal has a limited role in its treatment and only a stereotactic biopsy is necessary for confirming the diagnosis. METHODS: The data from all cases in whom the cerebral lymphomas were pathologically confirmed and were admitted to the Neurosurgery Department of Shohada Hospital for stereotactic biopsy during a 15-year period were analyzed retrospectively. RESULTS: The male to female ratio was 1.3:1 and the mean age was 51.7 years. Sixty-seven percent of the patients had multiple lesions and the remainder had solitary lesions. The most common site of involvement in patients with multiple lesions was diencephalon and in patients with solitary lesions was frontal lobe. The mean duration from symptom presentation to stereotactic biopsy was three months. Systemic lymphoma was detected in nine patients and three patients had a history of immunosuppressive drug consumption. The most common presenting symptom was headache in 42% and the most common sign was paresis in 59% of the patients. In 53 patients, follow-up was performed by phone call. Of these, seven cases had died without treatment in an average of 40 days after diagnosis, 28 patients died despite adjuvant treatment in an average of 8.5 months, and 18 cases were alive by the time of last follow-up with average of 17 months. Overall survival of the treated group was 12 months. CONCLUSION: There was no mortality related to stereotactic biopsies in these patients.

Diffusion Tensor Imaging for Glioma Grading: Analysis of Fiber Density Index.

INTRODUCTION: The most common primary tumors of brain are gliomas and tumor grading is essential for designing proper treatment strategies. The gold standard choice to determine grade of glial tumor is biopsy which is an invasive method. The purpose of this study was to investigate the role of fiber density index (FDi) by means of diffusion tensor imaging (DTI) (as a noninvasive method) in glial tumor grading. METHODS: A group of 20 patients with histologically confirmed diagnosis of gliomas were evaluated in this study. We used a 1.5 Tesla MR system (AVANTO; Siemens, Germany) with a standard head coil for scanning. Multidirectional diffusion weighted imaging (measured in 12 noncollinear directions), and T1 weighted nonenhanced were performed for all patients. We defined two regions of interest (ROIs); 1) White matter fibers near the tumor and 2) Similar fibers in the contralateral hemisphere. RESULTS: FDi of the low-grade gliomas was higher than those of high-grade gliomas, which was significant (P=0.017). FDi ratio (ratio of fiber density in vicinity of the tumor to homologous fiber tracts in the contralateral hemisphere) is higher in low-grade than high-grade tumors, (P=0.05). In addition, we performed ROC (receiver operating characteristic) curve and the area under curve (AUC) was 0.813(P=0.013). CONCLUSION: Our findings prove significant difference in FDi near by low-grade and high-grade gliomas. Therefore, FDi values and ratios are helpful in glial tumor grading.

Treatment of Cystic Craniopharyngioma with Intracystic Stereotactic Instillation of Phosphorus 32.

OBJECTIVE: Cystic craniopharyngiomas are considered the most common intracranial nonglial tumor in children with the tendency for cyst formations. The aim of this study was to evaluate the effect of intracystic phosphorus 32 (P32) therapies on controlling the growth of the cystic component of craniopharyngioma. MATERIALS & METHODS: This clinical study was conducted on 47 patients with cystic craniopharyngioma from March 1998 to June 2012 at Shohada Tajrish Hospital, Tehran, Iran. Patients were treated with stereotactic intracystic P32. The mean cyst volume was 23.5 ml, and the dose of radiation to the inner cyst wall was 250 Gy. RESULTS: The overall response rate was 78.1% and the mean survival was 113.1±11months. The survival rate at 1, 3, 5, and 10 years after p32 therapy was 91%, 77%, 73%, and 52%, respectively. There was no mortality related to the procedure and no visual or endocrinal deterioration. Visual improvement occurred in 88% of patients presented with recent deterioration due to the cyst enlargement. CONCLUSION: Intracystic p32 therapy was an effective and almost safe procedure for the treatment of cystic component of craniopharyngioma.

Brain metastases in cancer patients attending a Gamma Knife Center: A study from a single institute in Iran.

BACKGROUND: This study was aimed to explore data on brain metastases in cancer patients attending the Iranian Gamma Knife Center. METERIALS AND METHODS: This was a retrospective study. In all 5216 case records of patients who referred to the Iranian Gamma Knife Center for treatment of brain tumors during year 2003-2011 were reviewed. Data were explored to identify patients who developed brain metastases due to cancer and assessed the information as applied to cancer patients including survival analysis. RESULTS: Two hundred and twenty patients were identified as having brain metastases due to cancer. The mean age of patients was 54.0 (standard deviation [SD] =12.7) years. Patients were followed for an average of 7 months after treatment with gamma-knife. The median survival time for different the Graded Prognostic Assessment (GPA) was: GPA: 0-1, 4.0 ± 0.4 months; GPA: 1.5-2.5, 6.0 ± 0.7 months; GPA: 3, 9.0 ± 0.9 months; and GPA: 3.5-4.0, 12.0 ± 1.8 months and the overall median survival was 7.0 (SD = 0.6) months. CONCLUSION: The findings suggest that many cancer patients in Iran might develop brain metastasis. Although, this is not a very high incidence compared with the existing statistics from other countries, there is an urgent need to explore the issue further.

The role of stenosis ratio as a predictor of surgical satisfaction in patients with lumbar spinal canal stenosis: a receiver-operator characteristic (ROC) curve analysis.

BACKGROUND: The aim of this study was to elucidate independent factors that predict surgical satisfaction in lumbar spinal canal stenosis (LSCS) patients. METHODS: Patients who underwent surgery were grouped based on the age, gender, duration of symptoms, walking distance, Neurogenic Claudication Outcome Score (NCOS) and the stenosis ratio (SR) described by Lurencin. We recorded on 2-year patient satisfaction using standardized measure. The optimal cut-off points in SR, NCOS and walking distance for predicting surgical satisfaction were estimated from sensitivity and specificity calculations and receiver operator characteristic (ROC) curves. RESULTS: One hundred fifty consecutive patients (51 male, 99 female, mean age 62.4±10.9 years) were followed up for 34±13 months (range 24-49). One, two, three and four level stenosis was observed in 10.7%, 39.3%, 36.0 % and 14.0% of patients, respectively. Post-surgical satisfaction was 78.5% at the 2 years follow up. In ROC curve analysis, the asymptotic significance is less than 0.05 in SR and the optimal cut-off value of SR to predict worsening surgical satisfaction was measured as more than 0.52, with 85.4% sensitivity and 77.4% specificity (AUC 0.798, 95% CI 0.73-0.90; P<0.01). CONCLUSIONS: The present study suggests that the SR, with a cut-off set a 0.52 cross-sectional area, may be superior to walking distance and NCOS in patients with degenerative lumbar stenosis considered for surgical treatment. Using a ROC curve analysis, a radiological feature, the SR, demonstrated superiority in predicting patient satisfaction, compared to functional and clinical characteristics such as walking distance and NCOS.

The prediction of successful surgery outcome in lumbar disc herniation based on artificial neural networks.

BACKGROUND: The aim of this study was to develop an artificial neural networks (ANNs) model for predict successful surgery outcome in lumbar disc herniation (LDH). METHODS: An ANN model and a logistic regression (LR) model were used to predict outcomes outcomes. The age, gender, duration of symptoms, smoking status, surgical level, visual analog scale (VAS) of leg/ back pain, the Zung Depression Scale (ZDS), and the Japanese Orthopaedic Association (JOA) Score, were determined as the input variables for the established ANN model. The Macnab classification was used for outcome assessment. ANNs on data from LDH patients, who had surgery, were trained to predict 2-year successful discectomy using several input variables. Sensitivity analysis to the established ANN model was used to identify the relevant variables. For evaluating the two models, the area under a receiver operating characteristic (ROC) curve (AUC), accuracy rate of predicting, and Hosmer-Lemeshow (H-L) statistics were considered. RESULTS: A total of 203 (96 male, 107 female, mean age 48.3±9.8 years) patients were caterigized into training, testing, and validation data sets consisting of 101, 51, and 51 cases, respectively. Surgical successful outcome was: categorized as excellent, 32%; good, 40.9%; fair, 20.7% and poor, 6.4% at 2-year follow-up. Compared to the LR model, the ANN model showed better results: accuracy rate, 95.8%; H-L statistic, 41.5%; and AUC, 0.82% of patients. CONCLUSIONS: The findings show that an ANNs can predict successful surgery outcome with a high level of accuracy in LDH patients. Such information is of use in the clinical decision-making process.