Randolph Otto - Academia.edu (original) (raw)
Papers by Randolph Otto
Current problems in diagnostic radiology, Jan 14, 2015
The purpose of this article is to illustrate types of diagnostic errors and feedback given to rad... more The purpose of this article is to illustrate types of diagnostic errors and feedback given to radiologists, using cases to support and clarify these categories. A comment-enhanced peer review system may be leveraged to generate a comprehensive feedback categorization scheme. These include errors of observation, errors of interpretation, inadequate patient data gathering, errors of communication, interobserver variability, informational feedback, and compliments. Much of this feedback is captured through comments associated with interpretative agreements.
Pediatric Radiology, 2015
Imaging is crucial in expediting the diagnosis and guiding definitive therapy in children with ov... more Imaging is crucial in expediting the diagnosis and guiding definitive therapy in children with ovarian torsion. This article reviews the multimodality spectrum of imaging findings in pediatric ovarian torsion, focusing primarily on US appearances. We describe predisposing conditions that can lead to torsion, the pathological basis of the radiologic findings in ovarian torsion, and the common diagnostic pitfalls.
Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery, 2015
In this study, we used computed tomography measurements to investigate the feasibility of nasosep... more In this study, we used computed tomography measurements to investigate the feasibility of nasoseptal flap reconstruction of sellar defects in children, and we reviewed our institutional experience with the procedure. Cross-sectional and case series. Pediatric tertiary care facility. We obtained 10 normal maxillofacial scans for each year of age from birth to 18. Computer-assisted nasal and skull-base measurements were performed. Patients with incomplete pneumatization were excluded from analysis. Reconstruction was presumed feasible if the ratio of nasoseptal flap length to associated sellar defect length was greater than 1. Chart review identified surgical patients. Of 190 scans, 125 had complete pneumatization. Of these, 120 (96%) displayed a ratio of nasoseptal flap length to sellar defect length greater than 1, suggesting that reconstruction would be feasible. Mean ratio of flap length to defect length for all subjects was 1.47 (SD 0.33; 95% CI, 1.41-1.53). Only 5 of 125 patient...
Magnetic resonance imaging, 2011
When assessing liver iron content using relaxometry, an average relaxation rate (R1, R2 or R2*) i... more When assessing liver iron content using relaxometry, an average relaxation rate (R1, R2 or R2*) is usually determined from a region of interest or the entire liver. This is commonly performed by fitting the signal decay in individual voxels to an appropriate relaxation function. The voxel-level parameters resulting from the fits are combined to determine the average relaxation rate, and an empirically derived calibration curve is used to convert this single value to iron content. The goal of this study was to compare the precision and accuracy of this voxel-wise fitting to an alternative method that relies on first averaging the signals from all voxels within the region of interest and then determining the relaxation rate from a single fit. Systematic differences were observed when both methods were applied to clinical images. Mathematical simulations were employed to determine which method provided more robust estimates of the true relaxation rate. The mathematical simulations were...
Radiology Case Reports, 2009
Radiology Case Reports, Vol 4, No 2 (2009). ...
Pediatric Radiology, 2011
MRI is being increasingly used to evaluate tissue relaxation in the setting of iron overload. Dia... more MRI is being increasingly used to evaluate tissue relaxation in the setting of iron overload. Diagnostic accuracy is strongly dependent upon the acquisition and analysis methods employed. Typically, a multi-echo train of relaxation data is acquired, the resulting curve is fit using a non-linear (exponential) function, and the derived relaxation time is converted to iron concentration by a calibration formula derived from paired MRI-biopsy samples. A theoretically valid processing alternative is to fit a straight line to the relaxation data after logarithmic transformation (log-linear). This log-linear method is more computationally efficient, allowing a full relaxation map to be generated in near real time. This method is present on all scanner platforms and has been published for use in assessing iron concentration. These factors imply methodological validity. To use in vivo and simulation data to show that log-linear fitting can generate highly erroneous relaxation results in iron-loaded tissues. After IRB approval, exponential and linear fitting were compared in a cohort of 20 patients being evaluated for hepatic iron overload. Simulation analyses were performed to characterize the main factors impacting derived results. In human subjects, log-linear analyses demonstrated gross deviation from exponential results at a moderate relaxation shortening (T2* ~5 ms). Simulation analyses demonstrated that the discrepancy was caused by noise effects and additional signal components violating mono-exponential function shape. Log-linear processing results in increasingly erroneous estimation of T2* with iron-loading. Therefore, this method should not be employed for measurement of relaxation behavior in clinical samples.
Developmental Medicine & Child Neurology, 2009
Alzheimer's & Dementia, 2012
Paediatric anaesthesia, Jan 29, 2015
Knowledge of the normal nares-to-carina (NC) distance might prevent accidental bronchial intubati... more Knowledge of the normal nares-to-carina (NC) distance might prevent accidental bronchial intubation and be helpful when designing preformed endotracheal tubes (ETT). The aim was to measure NC distance and to examine whether a height/length-based 'modified Morgan formula' would give useful guidance for nasotracheal ETT depth positioning. Two groups were studied. A younger group consisted of nasally intubated postoperative patients. In these, NC distance was obtained as the sum of ETT length and the distance from the ETT tip to the carina, as measured from an anteroposterior chest X-ray. An older group consisted of children who had undergone computerized tomography (CT) examination including head, neck, and chest. In these, NC was measured directly from the CT image. The modified Morgan formula was derived from the NC vs height/length relationship. Nares-to-carina distance was best predicted by a linear equation based on patient height. The equation in the younger group (1 day...
Current problems in diagnostic radiology, Jan 14, 2015
The purpose of this article is to illustrate types of diagnostic errors and feedback given to rad... more The purpose of this article is to illustrate types of diagnostic errors and feedback given to radiologists, using cases to support and clarify these categories. A comment-enhanced peer review system may be leveraged to generate a comprehensive feedback categorization scheme. These include errors of observation, errors of interpretation, inadequate patient data gathering, errors of communication, interobserver variability, informational feedback, and compliments. Much of this feedback is captured through comments associated with interpretative agreements.
Pediatric Radiology, 2015
Imaging is crucial in expediting the diagnosis and guiding definitive therapy in children with ov... more Imaging is crucial in expediting the diagnosis and guiding definitive therapy in children with ovarian torsion. This article reviews the multimodality spectrum of imaging findings in pediatric ovarian torsion, focusing primarily on US appearances. We describe predisposing conditions that can lead to torsion, the pathological basis of the radiologic findings in ovarian torsion, and the common diagnostic pitfalls.
Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery, 2015
In this study, we used computed tomography measurements to investigate the feasibility of nasosep... more In this study, we used computed tomography measurements to investigate the feasibility of nasoseptal flap reconstruction of sellar defects in children, and we reviewed our institutional experience with the procedure. Cross-sectional and case series. Pediatric tertiary care facility. We obtained 10 normal maxillofacial scans for each year of age from birth to 18. Computer-assisted nasal and skull-base measurements were performed. Patients with incomplete pneumatization were excluded from analysis. Reconstruction was presumed feasible if the ratio of nasoseptal flap length to associated sellar defect length was greater than 1. Chart review identified surgical patients. Of 190 scans, 125 had complete pneumatization. Of these, 120 (96%) displayed a ratio of nasoseptal flap length to sellar defect length greater than 1, suggesting that reconstruction would be feasible. Mean ratio of flap length to defect length for all subjects was 1.47 (SD 0.33; 95% CI, 1.41-1.53). Only 5 of 125 patient...
Magnetic resonance imaging, 2011
When assessing liver iron content using relaxometry, an average relaxation rate (R1, R2 or R2*) i... more When assessing liver iron content using relaxometry, an average relaxation rate (R1, R2 or R2*) is usually determined from a region of interest or the entire liver. This is commonly performed by fitting the signal decay in individual voxels to an appropriate relaxation function. The voxel-level parameters resulting from the fits are combined to determine the average relaxation rate, and an empirically derived calibration curve is used to convert this single value to iron content. The goal of this study was to compare the precision and accuracy of this voxel-wise fitting to an alternative method that relies on first averaging the signals from all voxels within the region of interest and then determining the relaxation rate from a single fit. Systematic differences were observed when both methods were applied to clinical images. Mathematical simulations were employed to determine which method provided more robust estimates of the true relaxation rate. The mathematical simulations were...
Radiology Case Reports, 2009
Radiology Case Reports, Vol 4, No 2 (2009). ...
Pediatric Radiology, 2011
MRI is being increasingly used to evaluate tissue relaxation in the setting of iron overload. Dia... more MRI is being increasingly used to evaluate tissue relaxation in the setting of iron overload. Diagnostic accuracy is strongly dependent upon the acquisition and analysis methods employed. Typically, a multi-echo train of relaxation data is acquired, the resulting curve is fit using a non-linear (exponential) function, and the derived relaxation time is converted to iron concentration by a calibration formula derived from paired MRI-biopsy samples. A theoretically valid processing alternative is to fit a straight line to the relaxation data after logarithmic transformation (log-linear). This log-linear method is more computationally efficient, allowing a full relaxation map to be generated in near real time. This method is present on all scanner platforms and has been published for use in assessing iron concentration. These factors imply methodological validity. To use in vivo and simulation data to show that log-linear fitting can generate highly erroneous relaxation results in iron-loaded tissues. After IRB approval, exponential and linear fitting were compared in a cohort of 20 patients being evaluated for hepatic iron overload. Simulation analyses were performed to characterize the main factors impacting derived results. In human subjects, log-linear analyses demonstrated gross deviation from exponential results at a moderate relaxation shortening (T2* ~5 ms). Simulation analyses demonstrated that the discrepancy was caused by noise effects and additional signal components violating mono-exponential function shape. Log-linear processing results in increasingly erroneous estimation of T2* with iron-loading. Therefore, this method should not be employed for measurement of relaxation behavior in clinical samples.
Developmental Medicine & Child Neurology, 2009
Alzheimer's & Dementia, 2012
Paediatric anaesthesia, Jan 29, 2015
Knowledge of the normal nares-to-carina (NC) distance might prevent accidental bronchial intubati... more Knowledge of the normal nares-to-carina (NC) distance might prevent accidental bronchial intubation and be helpful when designing preformed endotracheal tubes (ETT). The aim was to measure NC distance and to examine whether a height/length-based 'modified Morgan formula' would give useful guidance for nasotracheal ETT depth positioning. Two groups were studied. A younger group consisted of nasally intubated postoperative patients. In these, NC distance was obtained as the sum of ETT length and the distance from the ETT tip to the carina, as measured from an anteroposterior chest X-ray. An older group consisted of children who had undergone computerized tomography (CT) examination including head, neck, and chest. In these, NC was measured directly from the CT image. The modified Morgan formula was derived from the NC vs height/length relationship. Nares-to-carina distance was best predicted by a linear equation based on patient height. The equation in the younger group (1 day...