This prospective, single-center observational study will evaluate the performance of an artificial intelligence (AI)-based automated image-analysis method that will be developed, internally tested, and locked before prospective enrollment. The method will estimate the position of totally implantable venous access port catheter tips in adults undergoing right internal jugular vein port implantation as part of routine care. The automated estimate will be compared with a prespecified manual measurement method. Reference measurements of the catheter tip and the cavoatrial junction will be obtained from clinically indicated chest computed tomography images when both structures are visible. No additional chest radiography or computed tomography will be performed for research purposes, and the automated output will not guide catheter placement or alter clinical decisions. The primary performance measure will be the mean absolute error of the automated estimate in the prospective cohort.
Before prospective enrollment, a two-dimensional nnU-Net-based multitask model will be developed and internally tested using retrospective chest radiographs from the same center. The model parameters, ensemble, preprocessing steps, and technical output rules will be locked before prospective enrollment. The retrospective development and internal test datasets are not part of the enrollment reported for this record. The prospective component will include one observational cohort of adults aged 18 years or older undergoing right internal jugular vein port implantation during routine clinical care. Implantation, chest radiography, computed tomography, and all clinical management decisions will remain under the responsibility of the treating clinical team and will not be assigned by the research protocol. The automated output will not be made available for procedural guidance or patient management. For each evaluable participant, the locked automated method will generate an estimate based on chest radiographic image analysis and a patient-specific Delta adjustment. A prespecified manual A+B measurement method will be applied as a comparator in the same participants. Reference measurements will be derived from the first suitable post-implantation noncontrast chest computed tomography examination obtained for a routine clinical indication, provided that both the catheter tip and the cavoatrial junction are visible and no catheter manipulation occurred beforehand. No additional radiographic or computed tomography examination will be requested for the study. The primary objective is to quantify the error of the automated estimate using mean absolute error in the prospective cohort. Prespecified secondary analyses will evaluate additional error, agreement, pragmatic accuracy, technical assessability, and repeatability measures. The ±10 mm criterion will be treated as a pragmatic accuracy threshold rather than a clinical safety boundary. The study is a same-center prospective performance evaluation; it is not an external validation and is not designed to assess clinical benefit or to establish that the system is ready for clinical use.
Study Type
OBSERVATIONAL
Enrollment
100
The locked automated method will use chest radiographic image analysis and a patient-specific Delta adjustment to estimate port catheter tip position. The method will be evaluated offline using reference measurements derived from clinically indicated post-implantation noncontrast chest computed tomography. Its output will not be provided to the clinical team and will not guide port implantation or alter clinical decisions.
The prespecified manual A+B method will estimate port catheter tip position using manual measurements on the pre-implantation chest radiograph. It will be applied as a comparator in the same participants. The manual research measurement will not guide port implantation or alter clinical care.
Bagcilar Training and Research Hospital
Bağcılar, Istanbul, Turkey (Türkiye)
Mean Absolute Error of Catheter Advancement Length Estimated by the AI-Based Automated A+B+Delta Method
Mean absolute error (MAE), in millimeters, will be calculated as the arithmetic mean of the absolute differences between the catheter advancement length estimated by the locked AI-based automated A+B+Delta method and the reference catheter advancement length derived from the first eligible post-implantation noncontrast chest computed tomography examination. The analysis population will include participants with both a valid automated output and an evaluable reference measurement. Lower values indicate smaller estimation error. A 95% confidence interval will be estimated using 10,000 participant-level bias-corrected and accelerated bootstrap resamples.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Median Absolute Error of Catheter Advancement Length Estimated by the AI-Based Automated A+B+Delta Method
Median absolute error (MedAE), in millimeters, will be calculated as the median of the absolute differences between the catheter advancement length estimated by the locked AI-based automated A+B+Delta method and the reference catheter advancement length derived from the first eligible post-implantation noncontrast chest computed tomography examination. The analysis population will include participants with both a valid automated output and an evaluable reference measurement. Lower values indicate smaller estimation error. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Root Mean Squared Error of Catheter Advancement Length Estimated by the AI-Based Automated A+B+Delta Method
Root mean squared error (RMSE), in millimeters, will be calculated as the square root of the arithmetic mean of the squared differences between the catheter advancement length estimated by the locked AI-based automated A+B+Delta method and the reference catheter advancement length derived from the first eligible post-implantation noncontrast chest computed tomography examination. The analysis population will include participants with both a valid automated output and an evaluable reference measurement. Lower values indicate smaller overall estimation error, and larger individual errors have greater influence because differences are squared before averaging. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Mean Signed Error of Catheter Advancement Length Estimated by the AI-Based Automated A+B+Delta Method
Mean signed error, in millimeters, will be calculated as the arithmetic mean of the catheter advancement length estimated by the locked AI-based automated A+B+Delta method minus the reference catheter advancement length derived from the first eligible post-implantation noncontrast chest computed tomography examination. The analysis population will include participants with both a valid automated output and an evaluable reference measurement. Positive values indicate that the automated method estimates a longer advancement length than the reference, negative values indicate a shorter estimate, and zero indicates no average directional error. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Mean Paired Difference in Absolute Error Between the AI-Based Automated A+B+Delta and Manual A+B Methods
For each participant, absolute error will be calculated for both the locked AI-based automated A+B+Delta method and the manual A+B method relative to the reference catheter advancement length derived from the first eligible post-implantation noncontrast chest computed tomography examination. The paired difference, in millimeters, will be calculated as automated absolute error minus manual absolute error, and its arithmetic mean will be reported. The analysis population will include participants with an evaluable reference measurement and valid estimates from both methods. Negative values indicate a smaller absolute error for the automated method, positive values indicate a smaller absolute error for the manual method, and zero indicates no average paired difference. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Proportion of AI-Based Automated A+B+Delta Estimates With Absolute Error Within 10 mm
The proportion of evaluable participants whose absolute error is 10 mm or less will be calculated for the locked AI-based automated A+B+Delta method. Absolute error will be defined as the absolute difference between the automated estimate and the reference catheter advancement length derived from the first eligible post-implantation noncontrast chest computed tomography examination. The denominator will include participants with both a valid automated output and an evaluable reference measurement, and the result will be reported as a percentage with a 95% Wilson score confidence interval. A higher percentage indicates that a larger proportion of estimates meet this prespecified pragmatic accuracy criterion. The 10 mm threshold is an operational technical accuracy criterion and not a clinical safety boundary.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Paired Difference in Proportions of Estimates With Absolute Error Within 10 mm Between the AI-Based Automated A+B+Delta and Manual A+B Methods
For each participant, the locked AI-based automated A+B+Delta estimate and the manual A+B estimate will each be classified by whether the absolute error from the reference catheter advancement length is 10 mm or less. The paired proportion difference, in percentage points, will be calculated as the automated qualifying proportion minus the manual qualifying proportion. The analysis population will include participants with an evaluable reference measurement and valid estimates from both methods. Positive values indicate a higher qualifying proportion for the automated method, and negative values indicate a higher qualifying proportion for the manual method. A 95% confidence interval will be calculated using Newcombe's method 10; an exact two-sided McNemar test will be used as an auxiliary analysis. The 10 mm threshold is a prespecified pragmatic accuracy criterion and not a clinical safety boundary.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Technical Success Rate of the AI-Based Automated A+B+Delta Method
Technical success will be defined as the generation of a valid numerical output by the AI-based automated A+B+Delta method after the method has been locked for prospective evaluation. The numerator will be the number of participants enrolled in the prospective cohort for whom the method generates a valid automated output, and the denominator will be all participants enrolled in the prospective cohort. A valid output requires the prespecified image-scale, anatomical-landmark, projection, image-quality, and uncertainty criteria to be satisfied. The result will be reported as a percentage with a 95% Wilson score confidence interval. Technical success will be reported separately from measurement accuracy among participants with evaluable reference data. A higher percentage indicates greater technical output availability and does not represent clinical effectiveness or safety.
Time frame: At baseline, during offline analysis of the pre-implantation chest radiograph obtained before port implantation
Intraobserver Agreement of the CT-Derived Catheter Tip-to-Cavoatrial Junction Distance Assessed by ICC(A,1)
Intraobserver agreement of the computed tomography (CT)-derived catheter tip-to-cavoatrial junction distance (dBT) will be assessed using a two-way random-effects, absolute-agreement, single-measure intraclass correlation coefficient \[ICC(A,1)\]. The same radiologist will repeat the dBT measurement in a prespecified random subset of 60 cases after a 4-week washout period, using newly assigned identifiers and reshuffled images while blinded to the initial measurement. Only cases evaluable at both readings will be analyzed. Higher ICC values indicate greater relative agreement. The estimate will be reported with a 95% confidence interval.
Time frame: At repeat assessment of the CT-derived reference measurement after a 4-week washout period
Mean Intraobserver Difference in the CT-Derived Catheter Tip-to-Cavoatrial Junction Distance
The mean signed difference (second reading minus first reading), in millimeters, will be calculated for the computed tomography-derived catheter tip-to-cavoatrial junction distance in the prespecified random subset of 60 cases measured twice by the same radiologist after a 4-week washout period. The radiologist will use newly assigned identifiers and reshuffled images and will be blinded to the initial measurement. Only cases evaluable at both readings will be analyzed. Positive values indicate a larger measurement at the second reading, negative values indicate a smaller measurement, and values closer to zero indicate less average systematic difference. A 95% confidence interval will be reported.
Time frame: At repeat assessment of the CT-derived reference measurement after a 4-week washout period
Within-Subject Standard Deviation of the CT-Derived Catheter Tip-to-Cavoatrial Junction Distance
Within-subject standard deviation (wSD), in millimeters, will quantify within-observer variation in the computed tomography-derived catheter tip-to-cavoatrial junction distance. In the prespecified random subset of 60 cases, the same radiologist will repeat the measurement after a 4-week washout period using newly assigned identifiers and reshuffled images while blinded to the initial measurement. Only cases evaluable at both readings will be analyzed. For these cases, wSD will be calculated as the standard deviation of the paired differences (second reading minus first reading) divided by the square root of 2. Lower values indicate less within-observer measurement variation. A chi-square-based 95% confidence interval will be reported.
Time frame: At repeat assessment of the CT-derived reference measurement after a 4-week washout period
Bland-Altman Limits of Agreement for the CT-Derived Catheter Tip-to-Cavoatrial Junction Distance
Bland-Altman limits of agreement (LoA), in millimeters, will be calculated for the CT-derived catheter tip-to-cavoatrial junction distance in a prespecified random subset of 60 cases measured twice by the same radiologist after a 4-week washout. Paired differences will be the second reading minus the first. The mean difference and LoA (mean difference +/- 1.96 times the standard deviation of paired differences) will be reported. Only cases evaluable at both readings will be analyzed. The radiologist will use new identifiers and reshuffled images while blinded to the initial measurement. The mean difference will have a t-based 95% confidence interval. Separate two-sided 95% confidence intervals for each LoA will be calculated using the exact noncentral t method, assuming normally distributed paired differences. Narrower limits indicate less within-observer measurement variation.
Time frame: At repeat assessment of the CT-derived reference measurement after a 4-week washout period
Repeatability Coefficient of the CT-Derived Catheter Tip-to-Cavoatrial Junction Distance
The repeatability coefficient (RC), in millimeters, will quantify within-observer repeatability of the computed tomography-derived catheter tip-to-cavoatrial junction distance in the prespecified random subset of 60 cases measured twice by the same radiologist after a 4-week washout period. Paired differences will be defined as the second reading minus the first reading. The RC will be calculated as 1.96 times the standard deviation of the paired differences. Only cases evaluable at both readings will be analyzed. The radiologist will use newly assigned identifiers and reshuffled images and will be blinded to the initial measurement. Lower RC values indicate less within-observer measurement variation. A chi-square-based 95% confidence interval will be reported.
Time frame: At repeat assessment of the CT-derived reference measurement after a 4-week washout period
Bland-Altman Limits of Agreement Between the AI-Based Automated A+B+Delta Estimate and the CT-Derived Reference
For participants with a valid automated output and an evaluable CT-derived reference measurement, paired differences, in millimeters, will be defined as the catheter advancement length estimated by the locked AI-based automated A+B+Delta method minus the CT-derived reference catheter advancement length. The mean difference and lower and upper 95% limits of agreement (LoA), calculated as the mean difference +/- 1.96 times the standard deviation of paired differences, will be reported. The mean difference will have a t-based 95% confidence interval. Separate two-sided 95% confidence intervals for each LoA will be calculated using the exact noncentral t method, assuming normally distributed paired differences. Positive differences indicate longer automated estimates than the reference, and negative differences indicate shorter estimates. This analysis describes agreement and does not establish clinical interchangeability or safety.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Mean Absolute Error of Catheter Advancement Length Estimated by the Manual A+B Method
Mean absolute error (MAE), in millimeters, will be calculated as the arithmetic mean of the absolute differences between the catheter advancement length estimated by the prespecified manual A+B measurement method and the CT-derived reference catheter advancement length. The analysis population will include participants with both a valid manual A+B estimate and an evaluable CT-derived reference measurement. Lower values indicate smaller estimation error. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Median Absolute Error of Catheter Advancement Length Estimated by the Manual A+B Method
Median absolute error (MedAE), in millimeters, will be calculated as the median of the absolute differences between the catheter advancement length estimated by the prespecified manual A+B measurement method and the CT-derived reference catheter advancement length. The analysis population will include participants with both a valid manual A+B estimate and an evaluable CT-derived reference measurement. Lower values indicate smaller estimation error. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Root Mean Squared Error of Catheter Advancement Length Estimated by the Manual A+B Method
Root mean squared error (RMSE), in millimeters, will be calculated as the square root of the arithmetic mean of the squared differences between the catheter advancement length estimated by the prespecified manual A+B measurement method and the CT-derived reference catheter advancement length. The analysis population will include participants with both a valid manual A+B estimate and an evaluable CT-derived reference measurement. Lower values indicate smaller overall estimation error, and larger individual errors have greater influence because differences are squared before averaging. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Mean Signed Error of Catheter Advancement Length Estimated by the Manual A+B Method
Mean signed error, in millimeters, will be calculated as the arithmetic mean of the catheter advancement length estimated by the prespecified manual A+B measurement method minus the CT-derived reference catheter advancement length. The analysis population will include participants with both a valid manual A+B estimate and an evaluable CT-derived reference measurement. Positive values indicate that the manual method estimates a longer advancement length than the reference, negative values indicate a shorter estimate, and zero indicates no average directional error. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Bland-Altman Limits of Agreement Between the Manual A+B Estimate and the CT-Derived Reference
For participants with a valid manual A+B estimate and an evaluable CT-derived reference measurement, paired differences, in millimeters, will be defined as the catheter advancement length estimated by the prespecified manual A+B method minus the CT-derived reference catheter advancement length. The mean difference and lower and upper 95% limits of agreement (LoA), calculated as the mean difference +/- 1.96 times the standard deviation of paired differences, will be reported. The mean difference will have a t-based 95% confidence interval. Separate two-sided 95% confidence intervals for each LoA will be calculated using the exact noncentral t method, assuming normally distributed paired differences. Positive differences indicate longer manual estimates than the reference, and negative differences indicate shorter estimates. This analysis describes agreement and does not establish clinical interchangeability or safety.
Time frame: At the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care, before any documented catheter manipulation or revision
Mean Absolute Error of the AI-Based Automated A+B+Delta Method Within 24 Hours After Port Implantation and Before Catheter Manipulation
In the prespecified sensitivity subset of participants whose first eligible post-implantation noncontrast chest computed tomography examination is obtained within 24 hours after port implantation and before any documented catheter manipulation, mean absolute error (MAE), in millimeters, will be calculated as the arithmetic mean of the absolute differences between the catheter advancement length estimated by the locked AI-based automated A+B+Delta method and the CT-derived reference catheter advancement length. Only participants with a valid automated output and an evaluable CT-derived reference measurement will be included. Lower values indicate smaller estimation error. A 95% confidence interval will be estimated using participant-level bootstrap resampling.
Time frame: Within 24 hours after port implantation and before any documented catheter manipulation, at the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care
Proportion of AI-Based Automated A+B+Delta Estimates With Absolute Error Within 10 mm Within 24 Hours After Port Implantation and Before Catheter Manipulation
In the prespecified sensitivity subset of participants whose first eligible post-implantation noncontrast chest computed tomography examination is obtained within 24 hours after port implantation and before any documented catheter manipulation, the proportion of evaluable participants whose absolute error is 10 mm or less will be calculated for the locked AI-based automated A+B+Delta method. Absolute error will be defined as the absolute difference between the automated estimate and the CT-derived reference catheter advancement length. The denominator will include participants with both a valid automated output and an evaluable CT-derived reference measurement. The result will be reported as a percentage with a 95% Wilson score confidence interval. The 10 mm threshold is a prespecified pragmatic technical accuracy criterion and not a clinical safety boundary.
Time frame: Within 24 hours after port implantation and before any documented catheter manipulation, at the first eligible post-implantation noncontrast chest computed tomography examination obtained during routine care
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