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Background: Dynamic Computed Tomography Angiography (4D CTA) has the potential of providing insight into the biomechanical properties of the vessel wall, by capturing motion of the vessel wall. For vascular pathologies, like intracranial aneurysms, this could potentially refine diagnosis, prognosis, and treatment decision‐making. Purpose: The objective of this research is to determine the feasibility of a 4D CTA scanner for accurately measuring harmonic diameter changes in an in‐vitro simulated vessel. Methods: A silicon tube was exposed to a simulated heartbeat. Simulated heart rates between 40 and 100 beats‐per‐minute (bpm) were tested and the flow amplitude was varied, resulting in various changes of tube diameter. A 320‐detector row CT system with ECG‐gating captured three consecutive cycles of expansion. Image registration was used to calculate the diameter change. A vascular echography set‐up was used as a reference, using a 9 MHz linear array transducer. The reproducibility of 4D CTA was represented by the Pearson correlation (r) between the three consecutive diameter change patterns, captured by 4D CTA. The peak value similarity (pvs) was calculated between the 4D CTA and US measurements for increasing frequencies and was chosen as a measure of temporal resolution. Spatial resolution was represented by the Sum of the Relative Percentual Difference (SRPD) between 4D CTA and US diameter change patterns for increasing amplitudes. Results: The reproducibility of 4D CTA measurements was good (r ≥ 0.9) if the diameter change was larger than 0.3 mm, moderate (0.7 ≤ r < 0.9) if the diameter change was between 0.1 and 0.3 mm, and low (r < 0.7) if the diameter change was smaller than 0.1 mm. Regarding the temporal resolution, the amplitude of 4D CTA was similar to the US measurements (pvs ≥ 90%) for the frequencies of 40 and 50 bpm. Frequencies between 60 and 80 bpm result in a moderate similarity (70% ≤ pvs < 90%). A low similarity (pvs < 70%) is observed for 90 and 100 bpm. Regarding the spatial resolution, diameter changes above 0.30 mm result in SRPDs consistently below 50%. Conclusion: In a phantom setting, 4D CTA can be used to reliably capture reproducible tube diameter changes exceeding 0.30 mm. Low pulsation frequencies (40 or 50 bpm) provide an accurate measurement of the maximum tube diameter change. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an automated approach model to define in vivo kinematics of the trapeziometacarpal (TMC) joint using four-dimensional computed tomography. A total of 15 healthy volunteers were included and their TMC joint kinematics were studied during a retropulsion-opposition-retropulsion movement. We used cardan angles estimated from transformation matrices using a ZYX-decomposition and analysed the motion of the thumb metacarpal relative to the trapezium, the thumb metacarpal relative to the index metacarpal, and the trapezium relative to the index metacarpal. The study also included an analysis of the joint hysteresis effect and a joint proximity model that estimated the joint contact area during a retropulsion-opposition-retropulsion movement. The automated approach significantly decreased the time needed to analyse each case and makes this model applicable for further research on TMC kinematics. [ABSTRACT FROM AUTHOR]

Abstract Introduction To diagnose sinusoidal obstruction syndrome/veno‐occlusive disease (SOS/VOD), transabdominal ultrasonography is usually used to detect hemodynamic changes, but we tried to detect the changes using four‐dimensional computed tomography (4D‐CT). A 42‐year‐old Japanese woman was diagnosed with late‐onset SOS/VOD with transabdominal ultrasonography and was also assessed using 4D‐CT. Method We analyzed the portal vein (PV) contrast effect every 1.5 seconds and plotted the values of the contrast effect. With this graph, we analyzed three hemodynamic parameters. Result We found that these parameters correlated with the patient's status and indicated stasis due to sinusoid constriction. Conclusion 4D‐CT may become a helpful tool to diagnose and follow up with SOS/VOD.

Lunotriquetral coalitions are the most common form of carpal coalition wherein the cartilage between the lunate and triquetrum ossification centers failed to undergo apoptosis. This technical case report examines the arthrokinematics of bilateral lunotriquetral coalitions with dissimilar Minnaar types in one participant with one asymptomatic wrist and one wrist with suspected distal radioulnar joint injury. Static and dynamic (four-dimensional) CT images during pronosupination were captured using a photon-counting detector CT scanner. Interosseous proximity distributions were calculated between the lunotriquetral coalition and adjacent bones in both wrists to quantify arthrokinematics. Interosseous proximity distributions at joints adjacent to the lunotriquetral coalition demonstrate differences in median and minimum interosseous proximities between the asymptomatic and injured wrists during resisted pronosupination. Altered kinematics from lunotriquetral coalitions may be a source of ulnar-sided wrist pain and discomfort, limiting the functional range of motion. This case report highlights potential alterations to wrist arthrokinematics in the setting of lunotriquetral coalitions and possible associations with ulnar-sided wrist pain, highlighting anatomy to examine in radiographic follow-up. Furthermore, this case report demonstrates the technical feasibility of four-dimensional CT using photon-counting detector technology in assessing arthrokinematics in the setting of variant wrist anatomy. [ABSTRACT FROM AUTHOR]

Objectives: This prospective study tested the diagnostic accuracy, and absolute agreement with MRI of a low-dose CT protocol for left ventricular ejection fraction (LVEF) measurement. Furthermore we assessed its potential for combining it with Chest-Abdomen-Pelvis CT (CAP-CT) for a one-stop examination. Materials & methods: Eighty-two patients underwent helical low-dose CT. Cardiac magnetic resonance imaging (MRI) was the reference standard. In fifty patients, CAP-CT was performed concurrently, using a modified injection protocol. In these, LVEF was measured with radioisotope cardiography (MUGA). Patients >18 years, without contrast media or MRI contraindications, were included. Bias was measured with Bland-Altman analysis, classification accuracy with Receiver Operating Characteristics, and inter-reader agreement with Intra-Class Correlation Coefficient (ICC). Correlation was examined using Pearson's correlation coefficients. CAP image quality was compared to previous scans with visual grading characteristics. Results: The mean CT dose-length-product (DLP) was 51.8 mGycm, for an estimated effective dose of 1.4 mSv, compared to 5.7 mSv for MUGA. CT LVEF bias was between 2 % and 10 %, overestimating end-diastolic volume. When corrected for bias, sensitivity and specificity of 100 and 98.5 % for classifying reduced LVEF (50 % MRI value) was achieved. ICC for MUGA was significantly lower than MRI and CT. Distinction of renal medulla and cortex was reduced in the CAP scan, but proportion of diagnostic scans was not significantly different from standard protocol. Conclusion: When corrected for inter-modality bias, CT classifies patients with reduced LVEF with high accuracy at a quarter of MUGA dose and can be combined with CAP-CT without loss of diagnostic quality.

Purpose: To retrospectively evaluate the depiction rate of feeding arteries in biopsy-proven clear cell renal cell carcinoma (CCRCC) on four-dimensional computed tomography angiography (4D-CTA) images. Materials and methods: This study included 22 patients with 22 CCRCC and 30 feeding arteries treated with transcatheter renal artery embolization. The depiction rate of the feeding arteries on preprocedural 4D-CTA was evaluated. Images were acquired by 320-row multi-detector computed tomography (CT) 15‒36 s after starting to inject a contrast agent (600 mg/kg iodine) intravenously into patients at 2.1 s intervals (11 phases). Two board-certified radiologists retrospectively assessed the feeder depiction rate in all 11 phases with reference to the procedural images as the gold standard. Discrepancies were resolved by consultation with a third radiologist. Results: Among the feeders, 11 (36.7%) were segmental or lobar, and 19 (63.3%) were interlobar or arcuate arteries. The feeder depiction rate was the highest (25 [83.3%] of 30) in the 5th phase (delay, 23.4 s) where the gap in contrast enhancement between the renal artery and cortex was the largest. This was followed by the 6th (23 [76.7%] of 30), 4th (22 [73.3%] of 30]), and 7th (21 [70.0%] of 30) phases. The overall rate of depicting feeding arteries in the 11 phases of 4D-CTA was 28 (93.3%) of 30. Conclusions: The depiction rate of CCRCC feeding arteries including lobar or smaller artery branches by 4D-CTA was favorable. The feeding arteries were optimally visualized during the phase with the largest contrast gap between the renal artery and cortex. [ABSTRACT FROM AUTHOR]

Objectives: CT perfusion (CTP) has been suggested to increase the rate of large vessel occlusion (LVO) detection in patients suspected of acute ischemic stroke (AIS) if used in addition to a standard diagnostic imaging regime of CT angiography (CTA) and non-contrast CT (NCCT). The aim of this study was to estimate the costs and health effects of additional CTP for endovascular treatment (EVT)–eligible occlusion detection using model-based analyses. Methods: In this Dutch, nationwide retrospective cohort study with model-based health economic evaluation, data from 701 EVT-treated patients with available CTP results were included (January 2018–March 2022; trialregister.nl:NL7974). We compared a cohort undergoing NCCT, CTA, and CTP (NCCT + CTA + CTP) with a generated counterfactual where NCCT and CTA (NCCT + CTA) was used for LVO detection. The NCCT + CTA strategy was simulated using diagnostic accuracy values and EVT effects from the literature. A Markov model was used to simulate 10-year follow-up. We adopted a healthcare payer perspective for costs in euros and health gains in quality-adjusted life years (QALYs). The primary outcome was the net monetary benefit (NMB) at a willingness to pay of €80,000; secondary outcomes were the difference between LVO detection strategies in QALYs (ΔQALY) and costs (ΔCosts) per LVO patient. Results: We included 701 patients (median age: 72, IQR: [62–81]) years). Per LVO patient, CTP-based occlusion detection resulted in cost savings (ΔCosts median: € − 2671, IQR: [€ − 4721; € − 731]), a health gain (ΔQALY median: 0.073, IQR: [0.044; 0.104]), and a positive NMB (median: €8436, IQR: [5565; 11,876]) per LVO patient. Conclusion: CTP-based screening of suspected stroke patients for an endovascular treatment eligible large vessel occlusion was cost-effective. Clinical relevance statement.: Although CTP-based patient selection for endovascular treatment has been recently suggested to result in worse patient outcomes after ischemic stroke, an alternative CTP-based screening for endovascular treatable occlusions is cost-effective. Key Points: • Using CT perfusion to detect an endovascular treatment-eligible occlusions resulted in a health gain and cost savings during 10 years of follow-up. • Depending on the screening costs related to the number of patients needed to image with CT perfusion, cost savings could be considerable (median: € − 3857, IQR: [€ − 5907; € − 1916] per patient). • As the gain in quality adjusted life years was most affected by the sensitivity of CT perfusion-based occlusion detection, additional studies for the diagnostic accuracy of CT perfusion for occlusion detection are required. [ABSTRACT FROM AUTHOR]

Background and purpose: Four-dimensional magnetic resonance imaging (4DMRI) has gained interest as an alternative to the current standard for motion management four-dimensional tomography (4DCT) in abdominal radiotherapy treatment planning (RTP). This review aims to assess the 4DMRI literature in abdomen, focusing on technical considerations and the validity of using 4DMRI for patients within radiotherapy protocols. Materials and methods: The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search was performed across the Medline, Embase, Scopus, and Web of Science databases, covering all years up to December 31, 2023. The studies were grouped into two categories: 4DMRI reconstructed from 3DMRI acquisition; and 4DMRI reconstructed from multi-slice 2DMRI acquisition. Results: A total of 39 studies met the inclusion criteria and were analysed to provide key findings. Key findings were 4DMRI had the potential to improve abdominal RTP for patients by providing accurate tumour definition and motion assessment compared to 4DCT. 4DMRI reconstructed from 3DMRI acquisition showed promise as a feasible approach for motion management in abdominal RTP regarding spatial resolution. Currently,the slice thickness achieved on 4DMRI reconstructed from multi-slice 2DMRI acquisitions was unsuitable for clinical purposes. Lastly, the current barriers for clinical implementation of 4DMRI were the limited availability of validated commercial solutions and the lack of larger cohort comparative studies to 4DCT for target delineation and plan optimisation. Conclusion: 4DMRI showed potential improvements in abdominal RTP, but standards and guidelines for the use of 4DMRI in radiotherapy were required to demonstrate clinical benefits.

PurposeMotion management of tumors within the lung and abdomen is challenging because it requires balancing tissue sparing with accuracy of hitting the target, while considering treatment delivery efficiency. Physicists can play an important role in analyzing four-dimensional computed tomography (4DCT) data to recommend the optimal respiratory gating parameters for a patient. The goal of this work was to develop a standardized procedure for making recommendations regarding gating parameters and planning margins for lung and gastrointestinal stereotactic body radiotherapy (SBRT) treatments. In doing so, we hoped to simplify decision-making and analysis, and provide a tool for troubleshooting complex cases.MethodsFactors that impact gating decisions and planning target volume (PTV) margins were identified. The gating options included gating on exhale with approximately a 50% duty cycle (Gate3070), exhale gating with a reduced duty cycle (Gate4060), and treating for most of respiration, excluding only extreme inhales and exhales (Gate100). A standard operating procedure was developed, as well as a physics consult document to communicate motion management recommendations to other members of the treatment team. This procedure was implemented clinically for 1 year and results are reported below.ResultsIdentified factors that impact motion management included the magnitude of motion observed on 4DCT, the regularity of breathing and quality of 4DCT data, and ability to observe the target on fluoroscopy. These were collated into two decision tables-one specific to lung tumors and another for gastrointestinal tumors-such that a physicist could answer a series of questions to determine the optimal gating and PTV margin. The procedure was used clinically for 252 sites from 213 patients treated with respiratory-gated SBRT and standardized practice across our 12-member physics team.ConclusionImplementation of a standardized procedure for respiratory gating had a positive impact in our clinic, improving efficiency and ease of 4DCT analysis and standardizing gating decision-making amongst physicists.

PurposeStandard four-dimensional computed tomography (4DCT) cardiac reconstructions typically include spiraling artifacts that depend not only on the motion of the heart but also on the gantry angle range over which the data was acquired. We seek to reduce these motion artifacts and, thereby, improve the accuracy of left ventricular wall positions in 4DCT image series.MethodsWe use a motion artifact reduction approach (ResyncCT) that is based largely on conjugate pairs of partial angle reconstruction (PAR) images. After identifying the key locations where motion artifacts exist in the uncorrected images, paired subvolumes within the PAR images are analyzed with a modified cross-correlation function in order to estimate 3D velocity and acceleration vectors at these locations. A subsequent motion compensation process (also based on PAR images) includes the creation of a dense motion field, followed by a backproject-and-warp style compensation. The algorithm was tested on a 3D printed phantom, which represents the left ventricle (LV) and on challenging clinical cases corrupted by severe artifacts.ResultsThe results from our preliminary phantom test as well as from clinical cardiac scans show crisp endocardial edges and resolved double-wall artifacts. When viewed as a temporal series, the corrected images exhibit a much smoother motion of the LV endocardial boundary as compared to the uncorrected images. In addition, quantitative results from our phantom studies show that ResyncCT processing reduces endocardial surface distance errors from 0.9 ± 0.8 to 0.2 ± 0.1 mm.ConclusionsThe ResyncCT algorithm was shown to be effective in reducing motion artifacts and restoring accurate wall positions. Some perspectives on the use of conjugate-PAR images and on techniques for CT motion artifact reduction more generally are also given.

OBJECTIVE: Today, respiratory movement can be monitored and recorded with different methods during a simulation on a four-dimensional (4D) computed tomography (CT) device to be used in radiotherapy planning. A synchronized respiratory monitoring system (RPM) with an externally equipped device is one of these methods. Another method is to create 4D images of the patient’s breathing phases without the need for extra equipment, with an anatomy-based software program integrated into the CT device. Our aim is to compare the RPM system and the software system (Deviceless) which are two different respiratory monitoring methods used in tracking moving targets during 4D-CT imaging and to assess their clinical usability. METHODS: Ten patients who underwent paraaortic nodal irradiation were enrolled. The simulation was performed using intravenous contrast material on a 4D-CT device with both respiratory monitoring methods. The right/left kidneys and renal arteries were chosen as references to evaluate abdominal organ movement. It was then manually contoured one by one on both sets of images. The images were compared volumetrically and geometrically after rigid reconstruction. The similarity between the contours was determined by the Dice index. Wilcoxon test was used for statistical comparisons. RESULTS: The motion of the kidneys in all three directions was found to be 0.0 cm in both methods. The shifts in the right/ left renal arteries were submillimetric. The Dice index showed a high similarity in both kidney and renal artery contours. CONCLUSION: In our study, no difference was found between RPM and Deviceless systems used for tracking and detection of moving targets during simulation in 4D-CT. Both methods can be used safely for radiotherapy planning according to the available possibilities in the clinic. [ABSTRACT FROM AUTHOR]

Left upper lobectomy (LUL) with left superior pulmonary vein (LSPV) resection alters the left atrium (LA) physiological states and LA hemodynamics associated with thrombosis, although this underlying mechanism is poorly understood. Therefore, we investigated the effects of LSPV resection and associated LA physiological changes on LA hemodynamics using four-dimensional computed tomography image-based computational simulations. Three cases were considered: the LA before and after LUL extracted from computed tomography images and artificial LSPV resection without physiological changes. Comparisons among the three cases demonstrated that physiological changes associated with LSPV resection are the possible factors that affect the LA hemodynamics after LUL. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to evaluate the real-world variation in CT perfusion (CTP) imaging protocols among stroke centers and to explore the potential for standardizing vendor software to harmonize CTP images. Methods: Stroke centers participating in a nationwide multicenter healthcare evaluation were requested to share their CTP scan and processing protocol. The impact of these protocols on CTP imaging was assessed by analyzing data from an anthropomorphic phantom with center-specific vendor software with default settings from one of three vendors (A–C): IntelliSpace Portal, syngoVIA, and Vitrea. Additionally, standardized infarct maps were obtained using a logistic model. Results: Eighteen scan protocols were studied, all varying in acquisition settings. Of these protocols, seven, eight, and three were analyzed with center-specific vendor software A, B, and C respectively. The perfusion maps were visually dissimilar between the vendor software but were relatively unaffected by the acquisition settings. The median error [interquartile range] of the infarct core volumes (mL) estimated by the vendor software was − 2.5 [6.5] (A)/ − 18.2 [1.2] (B)/ − 8.0 [1.4] (C) when compared to the ground truth of the phantom (where a positive error indicates overestimation). Taken together, the median error [interquartile range] of the infarct core volumes (mL) was − 8.2 [14.6] before standardization and − 3.1 [2.5] after standardization. Conclusions: CTP imaging protocols varied substantially across different stroke centers, with the perfusion software being the primary source of differences in CTP images. Standardizing the estimation of ischemic regions harmonized these CTP images to a degree. Clinical relevance statement: The center that a stroke patient is admitted to can influence the patient's diagnosis extensively. Standardizing vendor software for CT perfusion imaging can improve the consistency and accuracy of results, enabling a more reliable diagnosis and treatment decision. Key Points: • CT perfusion imaging is widely used for stroke evaluation, but variation in the acquisition and processing protocols between centers could cause varying patient diagnoses. • Variation in CT perfusion imaging mainly arises from differences in vendor software rather than acquisition settings, but these differences can be reconciled by standardizing the estimation of ischemic regions. • Standardizing the estimation of ischemic regions can improve CT perfusion imaging for stroke evaluation by facilitating reliable evaluations independent of the admission center. [ABSTRACT FROM AUTHOR]

Background: This study evaluates the tracking accuracy of the lung tumor volume and fiducial markers using four-dimensional computed tomography (4DCT) and fitted neural network models. Materials and Methods: This study utilized data from 31 patients (109 fiducial markers) who underwent stereotactic body radiotherapy (SBRT). The respiratory movements of fiducial markers, lung tumors, and lung volume were calculated using 4DCT. Cross-correlation coefficients were then calculated to analyze the phase movements of fiducial markers, lung tumors, lung volume, direction displacement, and lung area (upper, middle, and lower lobes). Statistical prediction models were used to evaluate the predictive accuracy of the left--right (LR), anterior--posterior (AP), cranial--caudal (CC), and three-dimensional (3D) cross-correlation coefficients between fiducial markers and lung tumors. The coefficient of determination (R2) was used to determine the accuracy of the statistical prediction models for the explanatory variables. Results: The correlation between fiducial marker and lung tumor, as well as lung tumor movement by time phase, yielded the following R² values--LR: 0.920, AP: 0.319, CC: 0.675, and 3D: 0.449 for the upper lobe; LR: 0.567, AP: 0.627, CC: 0.955, and 3D: 0.939 for the middle/lower lobes. Statistically significant differences were observed in the CC and 3D directions within each lower lobe. Conclusions: The respiratory movements of fiducial markers and lung tumors in lung SBRT show stronger correlation with the movement of lung volume in the middle/ lower lobes compared to that in the upper lobes. Combining a fiducial marker with lung volume improves the prediction accuracy of the respiratory movement of lung tumors. [ABSTRACT FROM AUTHOR]

Objective: CT imaging precisely and quantitatively analyzes the kinematics of the carpal bones to evaluate the etiology of related osteoarthritis. Previous studies have investigated the kinematics of the trapeziometacarpal joint using static CT scans of various postures including the pinch position. This study analyzed the in-vivo kinematics of the trapeziometacarpal joint during dynamic pinch motion in young healthy volunteers using four-dimensional CT. Materials and methods: Twelve healthy young volunteers participated in this study. Each participant held the pinch meter between their thumb and index finger and pinched it with maximum force for a period of 6 s. This series of movement was recorded using a four-dimensional CT. The surface data of the trapezium and first metacarpal of all frames were reconstructed, and bone movement at the trapeziometacarpal joint was calculated using sequential three-dimensional registration. The instantaneous pinch force of each frame was measured using a pointer on a pinch meter that was reconstructed from the CT data. Results: The first metacarpal was abducted (15.9 ± 8.3°) and flexed (12.2 ± 7.1°) relative to the trapezium, and significantly translated to the volar (0.8 ± 0.6 mm) and ulnar directions (0.9 ± 0.8 mm) with maximum pinch force. This movement consistently increased with the pinch force. Conclusion: This study successfully employed 4D-CT to precisely demonstrate changes in rotation and translation at the trapeziometacarpal joint during pinch motion for various instantaneous forces. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the detection rate of feeding arteries in renal cell carcinoma with automated feeder-detection software and determine the optimal imaging phase for accurate feeder detection with transarterial time-resolved computed tomography angiography. Materials and Methods: The performance of automated feeder-detection software was retrospectively evaluated using transarterial renal time-resolved computed tomography angiography images of 15 renal cell carcinomas (mean size, 22.1 mm); the images were obtained via the renal artery using a hybrid angio-CT system with 320-row computed tomography, across nine phases with 0.5-s intervals over a contrast delay time of 1.0–5.0 s. Automated feeder-detection software was applied to each phase in all tumors (135 image series in total). The feeder-detection rate (i.e., sensitivity) in each phase was evaluated, and the number of false feeders demonstrated by the software was counted for each tumor. Results: A total of 22 feeders were identified. The feeder-detection rate was the highest (95.5% [21/22]) at delay times of 1.5 s and 2.0 s and lower in later phases. At delay times of 1.0 s and 1.5 s, the software demonstrated no or only a few (≤ 3) false feeders in 93.3% (14/15) of the tumors. In later phases, however, many (≥ 4) false feeders were observed in > 50% of tumors. Conclusion: The automated feeder-detection software showed a favorable feeder-detection rate and may be useful in transarterial embolization for renal cell carcinoma. The optimal delay time to avoid the demonstration of false feeders and achieve a high detection accuracy was 1.5 s. Level of Evidence IV: Case Series. [ABSTRACT FROM AUTHOR]

This study developed a deep learning model for fully automatic segmentation and labelling of wrist bones from four-dimensional computed tomography (4DCT) scans. This is a crucial step towards implementing 4DCT for diagnosing wrist ligament lesions, reducing time-consuming analysis of extensive data. [ABSTRACT FROM AUTHOR]

Background: Four-dimensional computed tomography (4D-CT) acquires multiple CT images over time, allowing to visualize the respiratory motion of organs and tumors. In patients undergoing 4D-CT for stereotactic radiotherapy of intrathoracic tumors, 4D-CT provides the opportunity to study the incidental movements of the breast during normal breathing. A study protocol to investigate breast respiratory motion is presented herein. Methods: Patients with any primary cancer who underwent 4D-CT will be retrospectively selected from a radiotherapy treatment planning database. Study inclusion requires full lungs and breasts coverage in the 4D-CT images. Patients with advanced tumors are excluded. The protocol details breast locations of interest (upper, lower, inner, outer, central), specifies virtual breast tumor beds, and details how breast motion will be measured. Data will be analyzed to quantify the range of movements, to evaluate breast motion according to laterality and location, and to evaluate the correlation between movements of the breast and the intra-thoracic organs. Results: Results should provide quantitative information on the extent of breast movements during free breathing, which could be valuable to plan for respiratory control during breast radiotherapy. Conclusion: This study presents a protocol to investigate breast movements during normal breathing using 4D-CT. The findings will aid in planning respiratory control for breast radiotherapy. [ABSTRACT FROM AUTHOR]

In this cadaveric study, we report quantitative dynamic four-dimensional CT evaluation of the effect on wrist kinematics of three intercarpal arthrodeses during radial and ulnar deviation. In five wrists, we successively performed scaphocapitate, four-corner and two-corner fusions. Four-dimensional CT examinations were performed prior to dissection and after each arthrodesis. The lunocapitate gap, posterior lunocapitate angle, radiolunate radial gap, radiolunate ulnar gap and radiolunate angle were assessed. After scaphocapitate arthrodesis, in radial deviation, we noted midcarpal diastasis and dorsal displacement of the capitate. In ulnar deviation, there was correction of that incongruence. After four-corner and two-corner fusions, in radial deviation, we noted radial radiolunate impingement and ulnar radiolunate incongruence. In ulnar deviation, after two-corner fusion, ulnar radiolunate impingement and radial radiolunate incongruence were present contrary to four-corner fusion. Our findings confirm that the constant radiocarpal and midcarpal congruence during radioulnar deviation in normal wrists is no longer possible with intercarpal kinematic modifications after these arthrodeses. [ABSTRACT FROM AUTHOR]

Low baseline levels of parathyroid hormone (PTH) are associated with a higher rate of multiglandular disease, lower localization rates of preoperative imaging modalities, and a higher rate of unsuccessful minimally invasive parathyroidectomies. The objective of this study is to assess the diagnostic value of four-dimensional dynamic computed tomography (4D-CT) in localizing primary hyperparathyroidism (pHPT) in patients with low baseline PTH levels, compared to patients with high baseline PTH levels. Patients with pHPT who received a 4D-CT scan as part of their standard diagnostic evaluation were divided into two groups based on the following criteria: (1) preoperative PTH levels less than 100 pg/mL and (2) patients with preoperative PTH levels greater than 100 pg/mL. All patients underwent parathyroidectomy based on 4D-CT findings, with intraoperative parathyroid hormone monitoring. The lesion-based sensitivity of 4D-CT was 88% in patients with low baseline PTH levels and 94.7% in patients with high baseline PTH levels (p = 0.33). However, the success rate of image-guided resection based on 4D-CT findings was 71.4% in the low baseline PTH group compared to 90.6% in the high baseline PTH group (p = 0.06). Our study demonstrated that 4D-CT has a high lesion-based sensitivity in patients with pHPT and low baseline PTH levels but led to a relatively low rate of successful image-guided resection in patients with low baseline PTH levels. Therefore, it is important to exercise increased caution during 4D-CT-guided surgical exploration of patients with low baseline PTH levels to ensure successful surgical resection of all parathyroid lesions. [ABSTRACT FROM AUTHOR]

Objective: Pleural adhesions are challenging during lung cancer surgery and may be associated with a long surgery time and excessive blood loss due to pleural adhesiolysis. We used preoperative four-dimensional computed tomography to quantitatively assess parietal pleural adhesions and determine its diagnostic accuracy. Methods: A total of 216 patients with lung cancer underwent four-dimensional computed tomography during the study period. Pleural adhesions were subsequently confirmed by surgery in 85 of these patients, whereas 126 patients had no adhesions. The movements of the tumor or target vessels (α) was tracked. Receiver-operating characteristic curve analysis was used to identify the relationship between adhesions and (α). Results: The movement of (α) was smaller in patients with adhesions than in those without adhesions. The greater the adhesion, the shorter the movement distance (p < 0.001). Receiver-operating characteristic curve analysis demonstrated an area under the curve for the moving (α) point at 0.71 (95% confidence interval: 0.62–0.80) in the upper lung field and at 0.75 (95% confidence interval: 0.64–0.85) in the lower field. To identify adhesions, a cut off of 11.3 mm (sensitivity = 43.6%, specificity = 93.2%) in the upper lung field and a cut off of 41.2 mm (sensitivity = 71.4%, specificity = 66.0%) in the lower lung field were established. Conclusions: Four-dimensional computed tomography is a novel and helpful modality for predicting the presence of parietal pleural adhesions. To obtain robust evidence, further accumulation of cases and re-examination of the analysis methods are needed. [ABSTRACT FROM AUTHOR]

Background: Ultrasonography (US) and the 99mTc-sestamibi parathyroid scan (SPS) may have suboptimal accuracy when detecting the localization of enlarged parathyroid gland(s) (PTG). Therefore, the more accurate four-dimensional computed tomography scan (4D-CT) has been employed for PTG imaging. Currently, there is a paucity of data evaluating the utility of 4D-CT in low caseload settings. Aim and Objectives: To evaluate the impact of PTG imaging, using 4D-CT in conjunction with its intraoperatively displayed results, on the outcomes of surgical PTX. Materials and Methods: A single-center retrospective analysis of surgically treated patients with pHPT from 01/2010 to 01/2021 was conducted. An evaluation of the impact of the preoperative imaging modalities on the results of surgical treatment was carried out. Results: During the study period, 290 PTX were performed; 45 cases were excluded due to surgery for secondary, tertiary or recurrent HPT, or due to the use of alternative imaging techniques. The remaining 245 patients were included in the study. US was carried out for PTG imaging in 236 (96.3%), SPS in 93 (38.0%), and 4D-CT in 52 patients (21.2%). The use of 4D-CT was associated with a significantly higher rate of successful localization of enlarged PTG (49 cases, 94.2%) compared to US and SPS (74 cases, 31.4%, and 54 cases, 58.1%, respectively). We distinguished between three groups of patients based on preoperative imaging: (1) PTG lateralization via US or SPS in 106 (43.3%) cases; (2) precise localization of PTG via 4D-CT in 49 (20.0%) patients; and (3) in 90 cases (36.7%), PTG imaging failed to localize an enlarged gland. The group of 4D-CT localization had significantly shorter operative time, lower rate of simultaneous thyroid resections, as well as lower rate of removal of ≥2 PTG, compared to the other groups. The 4D-CT imaging was also associated with the lowest perioperative morbidity and with the lowest median PTH in the one month follow-up; however, compared to the other groups, these differences were statistically not significant. The implementation of 4D-CT (since 01/2018) was associated with a decrease in the need for redo surgery (from 11.5% to 7.3%) and significantly increased the annual case load of PTX at our institution (from 15.3 to 41.0) compared to the period before 4D-CT diagnostics. Conclusions: 4D-CT imaging enabled to precisely locate almost 95% of enlarged PTG in patients with pHPT. Accurate localization and intraoperatively displayed imaging results are useful guides for surgeons to make PTX a faster and safer procedure in a low-volume center. [ABSTRACT FROM AUTHOR]

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Background: Mobility of lung tumors is induced by respiration and causes inadequate dose coverage. Objective: This study quantified lung tumor motion, velocity, and stability for small (≤5 cm) and large (>5 cm) tumors to adapt radiation therapy techniques for lung cancer patients.Material and Methods: In this retrospective study, 70 patients with lung cancer were included that 50 and 20 patients had a small and large gross tumor volume (GTV). To quantify the tumor motion and velocity in the upper lobe (UL) and lower lobe (LL) for the central region (CR) and a peripheral region (PR), the GTV was contoured in all ten respiratory phases, using 4D-CT. Results: The amplitude of tumor motion was greater in the LL, with motion in the superior-inferior (SI) direction compared to the UL, with an elliptical motion for small and large tumors. Tumor motion was greater in the CR, rather than in the PR, by 63% and 49% in the UL compared to 50% and 38% in the LL, for the left and right lung. The maximum tumor velocity for a small GTV was 44.1 mm/s in the LL (CR), decreased to 4 mm/s for both ULs (PR), and a large GTV ranged from 0.4 to 9.4 mm/s. Conclusion: The tumor motion and velocity depend on the tumor localization and the greater motion was in the CR for both lobes due to heart contribution. The tumor velocity and stability can help select the best technique for motion management during radiation therapy.

Parathyroidectomy is the treatment of choice for primary hyperparathyroidism when the clinical criteria are met. Although bilateral neck exploration is traditionally the standard method for surgery, minimally invasive parathyroidectomy (MIP), or focused parathyroidectomy, has been widely accepted with comparable curative outcomes. For successful MIP, accurate preoperative localization of parathyroid lesions is essential. However, no consensus exists on the optimal approach for localization. Currently, ultrasonography and technetium-99m-sestamibi–single photon emission computed tomography/computed tomography are widely accepted in most cases. However, exact localization cannot always be achieved, especially in cases with multiglandular disease, ectopic glands, recurrent disease, and normocalcemic primary hyperparathyroidism. Therefore, new modalities for preoperative localization have been developed and evaluated. Positron emission tomography/computed tomography and parathyroid venous sampling have demonstrated improvements in sensitivity and accuracy. Both anatomical and functional information can be obtained by combining these methods. As each approach has its advantages and disadvantages, the localization study should be deliberately chosen based on each patient’s clinical profile, costs, radiation exposure, and the availability of experienced experts. In this review, we summarize various methods for the localization of hyperfunctioning parathyroid tissues in primary hyperparathyroidism.

Background: The Agatston score on noncontrast computed tomography (CT) scans is the gold standard for calcium load determination. However, contrast-enhanced CT is commonly used for patients with atherosclerotic cardiovascular diseases (ASCVDs), such as peripheral arterial occlusive disease (PAOD) and abdominal aortic aneurysm (AAA). Currently, there is no validated method to determine calcium load in the aorta and peripheral arteries with a contrast-enhanced CT. This study validated a length-adjusted calcium score (LACS) method for contrast-enhanced CT scans. Method: The LACS (calcium volume in mm3/arterial length in cm) in the abdominal aorta was calculated using four-phase liver CT scans of 30 patients treated between 2017 and 2021 at the University Medical Center Groningen (UMCG) with no aortic disease. Noncontrast CT scans were segmented with a 130 Hounsfield units (HU) threshold, and a patient-specific threshold was used for contrast-enhanced CTs. The LACS was calculated and compared from both segmentations. Secondly, the interobserver variability and the influence of slice thickness (0.75 mm vs. 2.0 mm) was determined. Results: There was a high correlation between the LACS from contrast-enhanced CT scans and the LACS of noncontrast CTs (R2 = 0.98). A correction factor of 1.9 was established to convert the LACS derived from contrast-enhanced CT to noncontrast CT scans. LACS interobserver agreement on contrast-enhanced CT was excellent (1.0, 95% confidence interval = 1.0–1.0). The 0.75 mm CT threshold was 541 (459–625) HU compared with 500 (419–568) HU on 2 mm CTs (p = 0.15). LACS calculated with both thresholds was not significantly different (p = 0.63). Conclusion: The LACS seems to be a robust method for scoring calcium load on contrast-enhanced CT scans in arterial segments with various lengths. [ABSTRACT FROM AUTHOR]

Purpose: Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage lung cancer. We aimed to examine the differences in failure patterns after SBRT according to the clinical T stage. Methods: A total of 120 patients with early-stage lung cancer (T1-3N0M0) who underwent SBRT were analysed. The clinical stage in patients whose tumours were in contact with the chest wall was confirmed using four-dimensional computed tomography (4D-CT). Local failure, regional node metastasis, and distant metastasis were confirmed from clinical charts. Results: Median follow-up time was 27.5 months (range 7–122) after SBRT. Thirteen patients were restaged from clinical T2 with visceral pleural invasion to T3 with chest wall invasion using 4D-CT analysis. Thirty-seven patients developed recurrences. The median progression-free survival (PFS) and overall survival (OS) were 38.1 and 53.8 months, respectively. The 3‑year PFS and OS rates were 50.7% and 60.3%, respectively. A significant difference was observed in PFS according to the clinical T stage (p = 0.001). No significant differences were observed in OS according to the clinical T stage (p = 0.213). The proportion of locoregional failures relative to distant metastasis decreased with progression from T1 to T3. The pleural dissemination rate was significantly higher in T3 tumours than in T1 and T2 tumours (p = 0.010). Conclusion: Clinical T stage is associated with PFS after SBRT for lung cancer. There were differences in the failure patterns according to T stage. 4D-CT might provide significant information for assessing chest wall invasion associated with unfavourable PFS. [ABSTRACT FROM AUTHOR]

Background: The effects of adrenal venous sampling (AVS) may be limited by the anatomical variants of adrenal veins. Purpose: To investigate the benefits of AVS for patients who underwent four-dimensional computed tomography (4D CT) before AVS. Material and Methods: We reviewed the images of contrast-enhanced four phase three-dimensional (3D) and 4D CT in patients who received AVS between February 2010 and February 2021. A total of 112 patients (59 women; mean age = 55.3 ± 11.8 years) were enrolled. Of the entire population, 49.1% (55/112) underwent 4D CT, whereas 50.9% (57/112) underwent 3D CT. The anatomical features of adrenal veins and procedural data were obtained. Simple linear regression analyses were performed to determine the relationship between imaging protocols and AVS. Results: On comparison of the two groups, the 4D cohort had a higher success rate (98.2% vs. 78.9%; P = 0.001), shorter procedure and fluoroscopy time (73.6 ± 37.3 min vs. 110.5 ± 47.9 min; P < 0.001 and 28.7 ± 31.2 min vs. 97.4 ± 251.7 min; P = 0.047, respectively), lower radiation exposure (243.5 ± 315.5 mGycm2 vs. 613.4 ± 674.6 mGycm2; P < 0.001) and less contrast volume (46.2 ± 42.7 ml vs. 68.3 ± 47.4 ml vs; P = 0.014). In simple linear regression analysis, positive and negative identification of right adrenal vein before AVS significantly influenced the success rate (unstandardized coefficients [UC] = 0.304, standardized coefficients [SC] = 0.304; P = 0.001) and operation duration (UC = −46.124, SC = −0.318; P = 0.001). Conclusion: Pre-procedural 4D CT may facilitate successful AVS. Compared with four-phase 3D CT, this protocol is better to shorten the operation and fluoroscopy time, and to reduce the radiation dose and contrast consumption. [ABSTRACT FROM AUTHOR]

Objective: Preoperative localization in patients with primary or secondary hyperparathyroidism before radiofrequency ablation (RFA) is crucial. There is currently a lack of consensus regarding imaging protocol. Evaluating the diagnostic performance of ultrasound, four-dimensional computed tomography (4D-CT), and technetium 99m-sestamibi single-photon-emission-computed tomography/computed tomography (SPECT/CT) is necessary for RFA of hyperparathyroidism. Methods: This retrospective study recruited patients with primary or secondary hyperparathyroidism who underwent ultrasound, 4D-CT, and SPECT/CT before RFA at a single institution. The sensitivity, accuracy, and receiver operating characteristic curve analysis were used to evaluate the diagnostic performance of the imaging modalities. Results: A total of 33 patients underwent RFA for hyperparathyroidism (8 patients with primary hyperparathyroidism, 25 patients with secondary hyperparathyroidism). Ultrasound had the highest sensitivity (0.953) and accuracy (0.943), while 4D-CT had higher sensitivity and accuracy than SPECT/CT (sensitivity/accuracy, 4D-CT vs. SPECT/CT: 0.929/0.920 vs. 0.741/0.716). Combined ultrasound with 4D-CT and the three combined modalities achieved equivalent, and the highest, diagnostic performance (sensitivity 1.000, accuracy 0.989). The lesion length and volume were important predictors of the diagnostic performance of 4D-CT and SPECT/CT (area under curve of length in 4D-CT/volume in 4D-CT/length in SPECT/volume in SPECT: 0.895/0.834/0.767/0.761). Conclusion: Combined ultrasound with 4D-CT provides optimal preoperative localization prior to RFA in patients with primary or secondary hyperparathyroidism. The length and volume of parathyroid lesions are determinative of the diagnostic performance of 4D-CT and SPECT/CT. [ABSTRACT FROM AUTHOR]

Background: Mobility of lung tumors is induced by respiration and causes inadequate dose coverage. Objective: This study quantified lung tumor motion, velocity, and stability for small (≲5 cm) and large (>5 cm) tumors to adapt radiation therapy techniques for lung cancer patients. Material and Methods: In this retrospective study, 70 patients with lung cancer were included that 50 and 20 patients had a small and large gross tumor volume (GTV). To quantify the tumor motion and velocity in the upper lobe (UL) and lower lobe (LL) for the central region (CR) and a peripheral region (PR), the GTV was contoured in all ten respiratory phases, using 4D-CT. Results: The amplitude of tumor motion was greater in the LL, with motion in the superior-inferior (SI) direction compared to the UL, with an elliptical motion for small and large tumors. Tumor motion was greater in the CR, rather than in the PR, by 63% and 49% in the UL compared to 50% and 38% in the LL, for the left and right lung. The maximum tumor velocity for a small GTV was 44.1 mm/s in the LL (CR), decreased to 4 mm/s for both ULs (PR), and a large GTV ranged from 0.4 to 9.4 mm/s. Conclusion: The tumor motion and velocity depend on the tumor localization and the greater motion was in the CR for both lobes due to heart contribution. The tumor velocity and stability can help select the best technique for motion management during radiation therapy. [ABSTRACT FROM AUTHOR]

Abstract Background Screening for osteoporosis with contrast-enhanced computed tomography (CT) is promising for identifying high-risk osteoporotic patients. Our aims were (1) to investigate the estimated volume bone mineral density (vBMD) change over time after contrast injection (CT perfusion imaging, CTPI); and (2) to examine the influence of contrast dose on vBMD. Methods Fifteen patients, aged 71 ± 9 years (mean ± standard deviation, range 55–86) underwent a CTPI examination (28 scans within 63 s) of the upper body followed (after a waiting time of 10 min) by a full 4-phase CT examination (4 scans within 4 min). The contrast dose for CTPI was 0.38–0.83 mL/kg, and for 4-phase CT was 0.87–1.29 mL/kg. Vertebrae L1–L3 were analysed totalling 43 vertebrae, using Mindways qCT Pro. Results After contrast injection, vBMD showed a near-horizontal line until 17.5 s (non-contrast phase), followed by a steep increase 17.5–41.5 s after contrast injection, i.e., in the arterial phase, which plateaued 41.5 s after, i.e., in the early venous phase. A higher contrast dose per kg yielded significantly higher vBMD increase in both the arterial and venous phase (p < 0.003). Conclusions Both time from contrast administration and contrast dose per kg affected vBMD results. In arterial phase, the steepness of the curve makes vBMD estimation unsure. However, as values plateaued in the venous phase it might be possible to predict the correct vBMD values. Furthermore, contrast dose is a factor that needs to be adjusted for when using such a formula.

Abstract Background As the collateral ligament reconstruction becomes more common to perform, the knowledge between the collateral ligament reconstruction and the elbow rotation axis is still ambiguous. The purpose of this study was to investigate the location of the intersections between the elbow rotation axis and medial and lateral aspect of the humerus. Methods Four-dimensional computed tomography (4D CT) scan was designed to obtain the images from 8 participants. The instantaneous rotation axis was created according to the trochlea notch of the ulna in the Rapidform XO software. Then the intersections between the instantaneous rotation axis and the medial and lateral aspect of the humerus were identified in the Geomagic Wrap software. Landmark coordinate systems of the distal humerus was created. Result The intersections in the medial aspect of the humerus were mostly located in the superior and posterior quadrant and showed the trend from anterior-superior to posterior-superior with the increment of the elbow flexion. The intersections in the lateral aspect of the humerus were mostly located in the middle half of the anterior quadrant and showed the trend from posterior-inferior to anterior-superior with the increment of the elbow flexion. Conclusion There’s no isometric point for medial collateral ligament (MCL) and lateral ulnar collateral ligament (LUCL) reconstruction. The isometric area for MCL reconstruction should be considered at the superior and posterior quadrant of the medial aspect of the humerus. The isometric area for LUCL reconstruction should be considered at the middle half of the anterior quadrant of the lateral aspect of the humerus. Trial registration This work was supported by the National Natural Science Foundation of China [ No.81911540488 ] in 07/01/2019.

Background/Aim. Four-dimensional (4D) computed tomography (CT) simulation is a useful tool for motion assessment in lung cancer radiotherapy. Conventional three-dimensional (3D) free-breathing (FB) simulation is static, with limited motion information on respiratory movements that can produce inaccuracies in the delineation process and radiotherapy planning. The aim of this study was to compare clinically significant differences between the target volumes defined on 3D CT vs. 4D CT simulation and the potential impact on the planning target volume (PTV), bearing in mind that a reduced PTV with precise coverage of the primary tumor is extremely important. In addition, quantification of movements of the primary tumor (gross tumor volume – GTV) was performed during 4D CT simulation on three axes: Z-superoinferior (SI), X-mediolateral (ML), and Y-anteroposterior (AP). Methods. This retrospective study evaluated 20 lung cancer patients who underwent CT simulation for radical radiotherapy treatment. FB 3D CT and 4D CT simulations were acquired for each patient in accordance with our institutional protocol. A volumetric comparison of radiation volumes defined on 3D CT vs. 4D CT simulation was done on the following: GTV 3D vs. internal GTV (IGTV) 4D and PTV 3D vs. internal PTV (IPTV) 4D. The comparison of GTV movement in the FB phase GTV (GTV FB), phase 0 (GTV 0), phase 50 (GTV 50), and phase maximum intensity projection (GTV MIP) was made with GTV FB as the basic value. The evaluation was made on all three axes. Results. The comparison of volumetric values between GTV 3D vs. IGTV 4D was 63.15 cm3 vs. 85.51 cm3 (p < 0.001), respectively. IGTV 4D was significantly larger than GTV 3D (p < 0.001). The mean value of equivalent spherical diameter (ESD) for PTV 3D vs. IPTV 4D was 8.44 cm vs. 7.82 cm (p < 0.001), respectively, and the mean value volume PTV 3D vs. IPTV 4D was 352.70 cm3 vs. 272.78 cm3 (p < 0.001), respectively. PTV 3D was significantly larger than IPTV 4D (p < 0.001). A statistically significant difference (p < 0.05) was identified in the deviation related to the Z-axis between the upper and lower lobe. Conclusion. 4D CT simulation-based delineation can reduce PTV compared to 3D simulation-based radiation therapy; therefore, it is a prerequisite for high-quality and precise radiation therapy treatment.

Background: Four-dimensional computed tomography (4D CT) is rapidly emerging as a diagnostic tool for the investigation of dynamic upper limb disorders. Dynamic elbow pathologies are challenging to diagnose, and at present, limitations exist in current imaging modalities Objective: We aimed to assess the clinical utility of 4D CT in detecting potential dynamic elbow disorders. Methods: Twenty-eight elbow joints from 26 patients with symptoms of dynamic elbow pathology were included in this study. They were first assessed by a senior orthopedic surgeon with subsequent qualitative data obtained via a Siemens Force Dual Source CT scanner (Erlangen, Germany), producing two- and three-dimensional “static” images and 4D dynamic “movie” images for assessment in each clinical scenario. Clinical assessment before and after scan was compared. Results: Use of 4D CT scan resulted in a change of diagnosis in 16 cases (57.14%). This included a change in primary diagnosis in 2 cases (7.14%) and secondary diagnosis in 14 cases (50%). In 25 cases (89.29%), the 4D CT scan allowed us to understand the pathological anatomy in greater detail which led to a change in the management plan of 15 cases (53.57%). Conclusion: 4D CT is a promising diagnostic tool in the management of dynamic elbow disorders and may be considered in clinical practice. Future studies need to compare it with other diagnostic modalities such as three-dimensional CT.

Background and purpose: In real-time lung tumor-tracking stereotactic body radiotherapy (SBRT), tracking accuracy is related to radiotherapy efficacy. This study aimed to evaluate the respiratory movement relationship between a lung tumor and a fiducial marker position in each direction using four-dimensional (4D) computed tomography (CT) images. Materials and methods: A series of 31 patients with a fiducial marker for lung SBRT was retrospectively analyzed using 4DCT. In the upper (UG) and middle and lower lobe groups (MLG), the cross-correlation coefficients of respiratory movement between the lung tumor and fiducial marker position in four directions (anterior–posterior, left–right, superior–inferior [SI], and three-dimensional [3D]) were calculated for each gating window (≤1, ≤2, and ≤ 3 mm). Subsequently, the proportions of phase numbers in unplanned irradiation (with lung tumors outside the gating window and fiducial markers inside the gating window) were calculated for each gating window. Results: In the SI and 3D directions, the cross-correlation coefficients were significantly different between UG (mean r = 0.59, 0.63, respectively) and MLG (mean r = 0.95, 0.97, respectively). In both the groups, the proportions of phase numbers in unplanned irradiation were 11 %, 28 %, and 63 % for the ≤ 1-, ≤2-, and ≤ 3-mm gating windows, respectively. Conclusions: Compared with MLG, fiducial markers for UG have low cross-correlation coefficients between the lung tumor and the fiducial marker position. Using 4DCT to assess the risk of unplanned irradiation in a gating window setting and selecting a high cross-correlation coefficient fiducial marker in advance are important for accurate treatment using lung SBRT.

Featured Application: Four-dimensional cardiac straightened segmentation can be useful for the periprocedural evaluation of TPVR. Cardiac computed tomography angiography (C-CTA) is crucial in assessing the right ventricular outflow tract (RVOT) prior to a transcatheter pulmonary valve replacement (TPVR), as an incorrect evaluation can make the procedure more challenging and can lead to device-related complications. This study aimed to evaluate the feasibility and accuracy of 4D straightened segmentation for a landing zone analysis over anatomical segmentation. Seven pre-operative CTAs and seven post-operative CTAs were used to measure the cross-sectional area, circumference, and diameters at five selected planes as the landing zone for TPVR and compared these to the 4D straightened model with the anatomical model. Furthermore, the right ventricular volume, stent volume, and 4D ellipticity index were calculated from the 4D straightened model. The 4D straightened segmentation had comparable accuracy and efficacy for the measurements at the landing zone. The cross-sectional area and the circumference varied greatly at the RVOT and the basal plane of the pulmonary valve compared with the other three planes of the 4D straightened models from the pre-operative CTAs; however, only the values at the RVOT were found to vary greatly from the post-operative CTAs. The 4D straightened model can provide accurate measurements and is thus a useful method for the periprocedural evaluation of TPVR. [ABSTRACT FROM AUTHOR]

Objectives: To compare the diagnostic performance of scapholunate gap (SLG) measurements acquired with dart throwing (DT), radio-ulnar deviation (RUD), and clenching fist (CF) maneuvers on 4D CT for the identification of scapholunate instability. Methods: In this prospective study, 47 patients with suspected scapholunate interosseous ligament (SLIL) tears were evaluated from March 2015 to March 2020 with semiautomatic quantitative analysis on 4D CT. Five parameters (median, maximal value, range, and coefficient of variation) for SLG, lunocapitate angle (LCA), and radioscaphoid angle (RSA) obtained during DT maneuver were evaluated in patients with and without SLIL tears. CT arthrography was used as the gold standard for the SLIL status. The SLG values obtained were also compared with those obtained during CF and RUD maneuvers. Results: Significant differences in all SLG- and LCA-derived parameters are found between patients with and without SLIL tears with DT (p < 0.003). The best diagnostic performance for the diagnosis of SLIL tears was obtained with median and maximal SLG values (sensitivity and specificity of 86–89% and 95%) and with maximal and range LCA values (sensitivity and specificity of 86% and 74%). No significant differences were observed for RSA values (p > 0.275). The SLG range obtained with DT maneuver was the only dynamic parameter statistically different between patients with partial and complete torn SLIL (p = 0.037). Conclusion: 4D CT of the wrist during DT showed a similar performance than RUD and a better performance than CF for the differentiation between patients with and without SLIL tears. Key Points: • Four-dimensional computed tomography can dynamically assess scapholunate instability. • The best results for differentiating between patients with and without SLIL tears were obtained with SLG median and maximal values. • The dart throwing and radio-ulnar deviation maneuvers yielded the best results for the dynamic evaluation of scapholunate instability. [ABSTRACT FROM AUTHOR]

Abstract: A 53-year-old woman of primary hyperparathyroidism with both ultrasound neck examination and planar 99m Tc-MIBI scan being negative revealed a tracer-avid focus in the left submandibular region in early (15 minutes postinjection) 99m Tc-MIBI SPECT/CT views, raising a suspicion of rare ectopic parathyroid adenoma. This finding was correlated on 4D-CT and confirmed on histopathology following surgical excision. Submandibular region is an unusual location for ectopic parathyroid adenoma. Nevertheless, high degree of suspicion with utilization of multimodality imaging including 99m Tc MIBI-SPECT/CT and 4D-CT improves preoperative detection of parathyroid adenoma at rare ectopic sites as seen in this case of persistent hyperparathyroidism., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

This study aimed to develop a novel internal target volume (ITV) definition for respiratory motion targets, considering target motion velocity and time. The proposed ITV was evaluated in respiratory-gated radiotherapy. An ITV modified with target motion velocity and time (ITVvt) was defined as an ITV that includes a target motion based on target motion velocity and time. The target motion velocity was calculated using four-dimensional computed tomography (4DCT) images. The ITVvts were created from phantom and clinical 4DCT images. The phantom 4DCT images were acquired using a solid phantom that moved with a sinusoidal waveform (peak-to-peak amplitudes of 10 and 20 mm and cycles of 2-6 s). The clinical 4DCT images were obtained from eight lung cancer cases. In respiratory-gated radiotherapy, the ITVvt was compared with conventional ITVs for beam times of 0.5-2 s within the gating window. The conventional ITV was created by adding a uniform margin as the maximum motion within the gating window. In the phantom images, the maximum volume difference between the ITVvt and conventional ITV was -81.9%. In the clinical images, the maximum volume difference was -53.6%. Shorter respiratory cycles and longer BTs resulted in smaller ITVvt compared with the conventional ITV. Therefore, the proposed ITVvt plan could be used to reduce treatment volumes and doses to normal tissues., Competing Interests: Declarations. Conflict of interest: The authors have no conflict to disclose. Ethical approval: All procedures involving human participants were performed in accordance with the ethical standards of the Institutional Review Board and the 1964 Helsinki Declaration and its later amendments. Ethical approval was not required for this study as we used the clinical 4DCT images from an open database., (© 2024. The Author(s), under exclusive licence to Japanese Society of Radiological Technology and Japan Society of Medical Physics.)

Four-Dimensional Computed Tomography Angiography (4D CTA) seems a promising technique for capturing vessel motion of cerebral arteries, which may help to assess pathological conditions such as intracranial aneurysms. The goal of our current observational study is to capture the lumen diameter of cerebral arteries during three subsequent cardiac cycles with 4D CTA and to assess vessel motion, anticipating consistent expansion patterns within each cardiac cycle. Eighteen adult patients with unruptured and untreated intracranial aneurysms were recruited at Radboud University Medical Center. Three cardiac cycles were captured, on a wide detector CT system, using ECG-gated 4D CTA. To reduce the impact of small head movements during the acquisition, a rigid-body registration was employed. Three 10 mm segments of cerebral arteries were selected. The total deformation of the vessel lumen was calculated using a deformable registration algorithm and was used as a substitute measure for vessel motion. No pulsations could be registered, which was probably caused by pulsation motion below threshold of detection in combination with insufficient Signal-to-Noise Ratio. Further studies need to investigate if large intracranial structures can be evaluated and if using a novel scanner with a high spatial resolution would result in reproducible measurements of arteries this size., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Frederick J.A. Meijer reports a relationship with Canon Medical Systems Corporation that includes: speaking and lecture fees. Hieronymus D. Boogaarts reports a relationship with Stryker that includes: consulting or advisory. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.]., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: A novel form of lung function imaging has been developed that uses 4-dimensional computed tomography (4DCT) data to generate lung ventilation images (4DCT-ventilation). Functional avoidance uses 4DCT-ventilation to reduce doses to functional lung with the aim of reducing pulmonary side effects. A phase 2, multicenter 4DCT-ventilation functional avoidance clinical trial was completed. The purpose of this work was to quantify changes in patient-reported outcomes (PROs) for patients treated with functional avoidance and determine which metrics are predictive of PRO changes., Materials and Methods: Patients with locally advanced lung cancer receiving curative-intent radiation therapy were accrued. Each patient had a 4DCT-ventilation image generated using 4DCT data and image processing. PRO instruments included the Functional Assessment of Cancer Therapy-Lung (FACT-L) questionnaire administered pretreatment; at the end of treatment; and at 3, 6, and 12 months posttreatment. Using the FACT-Trial Outcome Index and the FACT-Lung Cancer Subscale results, the percentage of clinically meaningful declines (CMDs) were determined. A linear mixed-effects model was used to determine which patient, clinical, dose, and dose-function metrics were predictive of PRO decline., Results: Of the 59 patients who completed baseline PRO surveys. 83% had non-small cell lung cancer, with 75% having stage 3 disease. The median dose was 60 Gy in 30 fractions. CMD FACT-Trial Outcome Index decline was 46.3%, 38.5%, and 26.8%, at 3, 6, and 12 months, respectively. CMD FACT-Lung Cancer Subscale decline was 33.3%, 33.3%, and 29.3%, at 3, 6, and 12 months, respectively. Although an increase in most dose and dose-function parameters was associated with a modest decline in PROs, none of the results were significant (all P > .053)., Conclusions: The current work presents an innovative combination of use of functional avoidance and PRO assessment and is the first report of PROs for patients treated with prospective 4DCT-ventilation functional avoidance. Approximately 30% of patients had clinically significant decline in PROs at 12 months posttreatment. The study provides additional data on outcomes with 4DCT-ventilation functional avoidance., (Copyright © 2024 Elsevier Inc. All rights reserved.)

A clinical, radiological and four-dimensional computed tomography (4DCT) assessment of the outcomes of scapholunate intercarpal ligamentoplasty (SLICL) was done with a minimum follow-up of 2 years. Twenty-nine patients (23 men and 6 women) with a mean age of 40 years (22-57) who had chronic scapholunate dissociation were treated with the SLICL procedure. There were 18 cases of dynamic instability and 11 of static instability. The patients were evaluated with a mean follow-up of 61 months (24-94). SLICL significantly reduced pain and increased grip strength and wrist function. On radiographs, the mean static and dynamic scapholunate gaps as well as the scapholunate and radiolunate angles improved significantly. The dorsal scaphoid displacement was always corrected. 4DCT after surgery provided a more precise analysis of the SLICL's effectiveness at restoring intracarpal alignment. Correction of the DISI deformity and dorsal scaphoid displacement was confirmed. SLICL restored a normal variation in the scapholunate gap (range value) during radioulnar deviation movement without systematically reducing the distance between the bones (mean and maximum values) which remained pathological in wrists with static instability but not in those with dynamic instability. At the final follow-up, no patients had signs of osteoarthritis due to ScaphoLunate Advanced Collapse. LEVEL OF EVIDENCE: III., (Copyright © 2024 SFCM. Published by Elsevier Masson SAS. All rights reserved.)

The aim of this study was to develop an automated approach model to define in vivo kinematics of the trapeziometacarpal (TMC) joint using four-dimensional computed tomography. A total of 15 healthy volunteers were included and their TMC joint kinematics were studied during a retropulsion-opposition-retropulsion movement. We used cardan angles estimated from transformation matrices using a ZYX-decomposition and analysed the motion of the thumb metacarpal relative to the trapezium, the thumb metacarpal relative to the index metacarpal, and the trapezium relative to the index metacarpal. The study also included an analysis of the joint hysteresis effect and a joint proximity model that estimated the joint contact area during a retropulsion-opposition-retropulsion movement. The automated approach significantly decreased the time needed to analyse each case and makes this model applicable for further research on TMC kinematics., Competing Interests: Declaration of conflicting interestsThe authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Low baseline levels of parathyroid hormone (PTH) are associated with a higher rate of multiglandular disease, lower localization rates of preoperative imaging modalities, and a higher rate of unsuccessful minimally invasive parathyroidectomies. The objective of this study is to assess the diagnostic value of four-dimensional dynamic computed tomography (4D-CT) in localizing primary hyperparathyroidism (pHPT) in patients with low baseline PTH levels, compared to patients with high baseline PTH levels. Patients with pHPT who received a 4D-CT scan as part of their standard diagnostic evaluation were divided into two groups based on the following criteria: (1) preoperative PTH levels less than 100 pg/mL and (2) patients with preoperative PTH levels greater than 100 pg/mL. All patients underwent parathyroidectomy based on 4D-CT findings, with intraoperative parathyroid hormone monitoring. The lesion-based sensitivity of 4D-CT was 88% in patients with low baseline PTH levels and 94.7% in patients with high baseline PTH levels (p = 0.33). However, the success rate of image-guided resection based on 4D-CT findings was 71.4% in the low baseline PTH group compared to 90.6% in the high baseline PTH group (p = 0.06). Our study demonstrated that 4D-CT has a high lesion-based sensitivity in patients with pHPT and low baseline PTH levels but led to a relatively low rate of successful image-guided resection in patients with low baseline PTH levels. Therefore, it is important to exercise increased caution during 4D-CT-guided surgical exploration of patients with low baseline PTH levels to ensure successful surgical resection of all parathyroid lesions.

Background: Ultrasonography (US) and the 99mTc-sestamibi parathyroid scan (SPS) may have suboptimal accuracy when detecting the localization of enlarged parathyroid gland(s) (PTG). Therefore, the more accurate four-dimensional computed tomography scan (4D-CT) has been employed for PTG imaging. Currently, there is a paucity of data evaluating the utility of 4D-CT in low caseload settings. Aim and Objectives: To evaluate the impact of PTG imaging, using 4D-CT in conjunction with its intraoperatively displayed results, on the outcomes of surgical PTX. Materials and Methods: A single-center retrospective analysis of surgically treated patients with pHPT from 01/2010 to 01/2021 was conducted. An evaluation of the impact of the preoperative imaging modalities on the results of surgical treatment was carried out. Results: During the study period, 290 PTX were performed; 45 cases were excluded due to surgery for secondary, tertiary or recurrent HPT, or due to the use of alternative imaging techniques. The remaining 245 patients were included in the study. US was carried out for PTG imaging in 236 (96.3%), SPS in 93 (38.0%), and 4D-CT in 52 patients (21.2%). The use of 4D-CT was associated with a significantly higher rate of successful localization of enlarged PTG (49 cases, 94.2%) compared to US and SPS (74 cases, 31.4%, and 54 cases, 58.1%, respectively). We distinguished between three groups of patients based on preoperative imaging: (1) PTG lateralization via US or SPS in 106 (43.3%) cases; (2) precise localization of PTG via 4D-CT in 49 (20.0%) patients; and (3) in 90 cases (36.7%), PTG imaging failed to localize an enlarged gland. The group of 4D-CT localization had significantly shorter operative time, lower rate of simultaneous thyroid resections, as well as lower rate of removal of ≥2 PTG, compared to the other groups. The 4D-CT imaging was also associated with the lowest perioperative morbidity and with the lowest median PTH in the one month follow-up; however, compared to the other groups, these differences were statistically not significant. The implementation of 4D-CT (since 01/2018) was associated with a decrease in the need for redo surgery (from 11.5% to 7.3%) and significantly increased the annual case load of PTX at our institution (from 15.3 to 41.0) compared to the period before 4D-CT diagnostics. Conclusions: 4D-CT imaging enabled to precisely locate almost 95% of enlarged PTG in patients with pHPT. Accurate localization and intraoperatively displayed imaging results are useful guides for surgeons to make PTX a faster and safer procedure in a low-volume center.

Objective: The tibia externally rotates to the femur during the last 20° of the knee extension motion. This kinematic phenomenon is well known as screw home movement (SHM). The purpose was to clarify the SHM in anterior cruciate ligament deficient (ACLD) knee using four-dimensional computed tomography (4DCT). Materials and methods: Six patients with a unilateral isolated ACLD knee participated. In the static position, CT scan of the both limbs of the femur and tibia were performed. Then, 4DCT was performed around knee. In the CT gantry, subjects were positioned in supine position with 45° of knee flexion on a triangle pillow and were asked to extend the knee to full extension within 10 s on each limb. The CT data were accumulated in digital imaging and communication in medicine (DICOM) data format. From the static CT and 4DCT DICOM data, three-dimensional surfaces of the knee joint were reconstructed. The whole tibia surface was matched into the partial tibia surface of that frame using 3D-3D registration technique. After the assessment of coordination system of the whole leg, knee flexion, abduction, and external rotation angle were calculated. Results: Knee external rotation angle was significantly smaller on the ACLD side than on the contralateral unaffected side in 0–15° of knee flexion (P < 0.05 in 0, 5, 10, and 15 degrees), while the angle was similar during 15–60° of knee flexion. Conclusion: The absence of SHM in ACLD knee was detected using 3D-3D registration technique based on 4DCT. [ABSTRACT FROM AUTHOR]

Objectives: Tumour size measurement is pivotal for staging and stratifying patients with pancreatic ductal adenocarcinoma (PDA). However, computed tomography (CT) frequently underestimates tumour size due to insufficient depiction of the tumour rim. CT-derived fractal dimension (FD) maps might help to visualise perfusion chaos, thus allowing more realistic size measurement. Methods: In 46 patients with histology-proven PDA, we compared tumour size measurements in routine multiphasic CT scans, CT-derived FD maps, multi-parametric magnetic resonance imaging (mpMRI), and, where available, gross pathology of resected specimens. Gross pathology was available as reference for diameter measurement in a discovery cohort of 10 patients. The remaining 36 patients constituted a separate validation cohort with mpMRI as reference for diameter and volume. Results: Median RECIST diameter of all included tumours was 40 mm (range: 18–82 mm). In the discovery cohort, we found significant (p = 0.03) underestimation of tumour diameter on CT compared with gross pathology (Δdiameter3D = −5.7 mm), while realistic diameter measurements were obtained from FD maps (Δdiameter3D = 0.6 mm) and mpMRI (Δdiameter3D = −0.9 mm), with excellent correlation between the two (R2 = 0.88). In the validation cohort, CT also systematically underestimated tumour size in comparison to mpMRI (Δdiameter3D = −10.6 mm, Δvolume = −10.2 mL), especially in larger tumours. In contrast, FD map measurements agreed excellently with mpMRI (Δdiameter3D = +1.5 mm, Δvolume = −0.6 mL). Quantitative perfusion chaos was significantly (p = 0.001) higher in the tumour rim (FDrim = 4.43) compared to the core (FDcore = 4.37) and remote pancreas (FDpancreas = 4.28). Conclusions: In PDA, fractal analysis visualises perfusion chaos in the tumour rim and improves size measurement on CT in comparison to gross pathology and mpMRI, thus compensating for size underestimation from routine CT. Key Points: • CT-based measurement of tumour size in pancreatic adenocarcinoma systematically underestimates both tumour diameter (Δdiameter = −10.6 mm) and volume (Δvolume = −10.2 mL), especially in larger tumours. • Fractal analysis provides maps of the fractal dimension (FD), which enable a more reliable and size-independent measurement using gross pathology or multi-parametric MRI as reference standards. • FD quantifies perfusion chaos—the underlying pathophysiological principle—and can separate the more chaotic tumour rim from the tumour core and adjacent non-tumourous pancreas tissue. [ABSTRACT FROM AUTHOR]