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Background: Dry powder inhaler (DPI) use requires sufficient peak inspiratory flow over the DPI internal resistance (PIFR). Objectives: We examined whether spirometric peak inspiratory flow (PIFspiro) could serve to predict PIFR in patients with obstructive lung disease. Method: Thirty healthy nonsmokers and 140 stable outpatients (70 COPD, 70 asthma) performed spirometry according to the 2019 ERS/ATS spirometry update, yielding PIFspiro. Using a PIFR measurement device with varying orifices, all subjects’ PIFR values were recorded for 5 predefined resistance levels, characterized by 5 orifice cross sections (SR). A test group including all healthy subjects, 30 of the asthma, and 30 of the COPD patients was used to establish the relationship between PIFR and both PIFspiro and SR by multiple regression. A validation group including the remaining 40 asthma and 40 COPD patients, served to verify whether their predicted PIFR value corresponded to the measured PIFR for each resistance level. Results: The asthma (FEV1 = 78 ± 17 [SD] %pred) and COPD (FEV1 = 46 ± 17 [SD] %pred) patients under study had varying airway obstruction. In the test group, PIFR could be predicted by ln[PIFspiro] (p < 0.0001), SR (p < 0.0001), and SR2 (p = 0.006), with an adjusted R2 = 0.71. In the validation group, estimated PIFR did not significantly differ from measured PIFR (p > 0.05 for the 5 resistance levels). Conclusions: We propose a simple method to predict PIFR for a range of common DPI resistances, based on the device characteristics and on the patient’s characteristics reflected in PIFspiro. As such, routine spirometry can serve to estimate a patient’s specific PIFR without the need for additional testing.

PURPOSE: (1) to assess the influence of medial or lateral imaging plane inclination on the measurement of sulcus angle, trochlear depth, and facet asymmetry on transverse cross-sectional images. (2) to assess the effect of measurement level (height) on these respective parameters. MATERIALS AND METHODS: Twenty dry femurs (9 left, 11 right) were imaged with CT. A 3D dataset was obtained from which axial images were reconstructed in the ideal plane without inclination as well as with 8° of medial and lateral inclination. Sulcus angle, trochlear depth, and facet asymmetry were measured on the 3 image sets. In addition, the measurements were performed at 5 mm and 10 mm from the superior margin of the medial trochlear facet. Statistical analysis consisted of the Wilcoxon test and calculation of measurement variation. RESULTS: There were no statistically significant differences between the indicated measurements on the reference set compared to medial or lateral inclination. All measurements were significantly different depending on measurement height. CONCLUSION: Medial or lateral inclination in the transverse imaging plane of 8° does not influence the values of typical parameters used for the assessment of trochlear dysplasia. The measurement height has a significant influence, and a consensus should be found as to which is the optimal measurement height.

Objectives: To compare the amount of fluid in synovial sheaths of the ankle before and after running. Our hypothesis was that this amount would increase, and that the threshold for what is normally acceptable should be adjusted after physical activity.Methods: Twenty-one healthy volunteers (n=42 ankles) ran for 40 minutes on a treadmill. They underwent 3T MRI before and immediately after running using a dedicated ankle coil. The images were stored and subsequently measured in a standardized way and independently read by two readers for fluid in the tendon sheaths in the retro and inframalleolar area. Statistics were performed for each tendon (Wilcoxon signed rank test), and also for the pooled data. Intraclass correlation coefficients were calculated.Results: For reader 1, for all tendons the values after running increased without reaching statistical significance. For reader 2 this was not the case for all tendons but for most. When all the data were pooled (n=800 measurements), the statistical difference before and after running was significant (p< 0.001).Conclusion: Data pre and post running show a trend of increasing synovial fluid, however not significant for each individual tendon. The pooled data for all tendons, (n=800) show a statistically significant increase after running (p< 0.001). The clinical implication is that the threshold for normally acceptable fluid should be adjusted if the patient undergoes an MR study after recent physical activity.

Purpose. The objective of this study was to analyse the possibilities of using 4D CT scanning for the tracking of patients’ mandibles. Methods. A clinical 256-slice Revolution CT was used in obtaining 4D CT scans without table movement, with a novel mandibular phantom, mounted on a programmable six degrees-of-freedom Stewart Platform in motion. The phantom was used to simulate mandibular motions which are combinations of rotations with translations (depression, elevation, protrusion, retrusion and laterotrusion). The phantom was scanned five times during identical motion patterns with a dynamic CT acquisition protocol. An image processing workflow consisting of a pairwise rigid registration and semi-automatic segmentation was developed to extract kinematic parameters (cardan angles and point-of-interest displacements) from the dynamic sequences. Reproducibility was investigated by the 95% confidence interval and the absorbed organ dose to organs of interest in the primary beam were also estimated and compared to those of a standard CT scan of the brain Results. The maximum average 95% confidence interval for the displacement across all time points for the five repetitions was 0.61 mm (Y axis). In terms of rotations, the maximum average 95% confidence interval across all time points for the five repetitions was 1.39° (X axis). The effective dose for the dynamic scan was found to be 1.3 mSv, for a CTDIvol of 63.95 mGy and a DLP of 1023.14 mGycm. The absorbed organ doses were similar to organ doses during a clinical head CT scan. Conclusions. A framework is proposed to use 4D CT scanning as a possible methodology to evaluate the motion of the temporomandibular joint. The scanning protocol allows to visualise the motion by applying a semi-automated segmentation and registration. A graphical representation of all displacements in the three spatial dimensions can depict multiple points-of-interest at once during the same acquisition. A novel type of phantom was also introduced which simulates mandibular movement with six degrees-of-freedom (three translations and three rotations).

BACKGROUND: Unoptimized coronary CT angiography (CTA) exams typically result in a highly variable arterial enhancement (HUa ) across patients. This study aimed at harmonizing arterial enhancement by implementing a patient-, contrast- and kV-tailored injection protocol. METHODS: First, the optimal body size metric to predict HUa was identified by retrospectively analysing images of 76 patients, acquired with 70 ml contrast media (G1). Second, using phantom experiments, correction factors for the effect of kV and contrast concentration on HUa were determined. Third, a model was developed, prescribing the optimal contrast dose to be injected to obtain a diagnostically appropriate arterial target enhancement HUtarget . The model was then validated on 278 prospectively collected patients, in two groups with two different HUtarget : 525 HU (207 patients, G2A) and 425 HU (71 patients, G2B). The HUa histograms were compared among groups and to the target enhancement through their mean and standard deviation (SD) at 100 kVp reference level. Also, signal-to-noise ratio was obtained and compared among the groups. RESULTS: Fat free mass (FFM) showed the highest correlation with HUa (r = 0.69). KVp correction factors ranged from 0.65 at 70 kVp to 1.22 at 140 kVp. The obtained model reduced the group heterogeneity (SD) from 101HU for reference G1 to 75HU (p

OBJECTIVES: To quantitatively evaluate the impact of a cardiac acquisition CT mode on motion artifacts in comparison to a conventional cine mode for dynamic musculoskeletal (MSK) imaging. METHODS: A rotating PMMA phantom with air-filled holes drilled at varying distances from the disk center corresponding to linear hole speeds of 0.75 cm/s, 2.0 cm/s, and 3.6 cm/s was designed. Dynamic scans were obtained in cardiac and cine modes while the phantom was rotating at 48°/s in the CT scanner. An automated workflow to compute the Jaccard distance (JD) was established to quantify degree of motion artifacts in the reconstructed phantom images. JD values between the cardiac and cine scan modes were compared using a paired sample t-test. In addition, three healthy volunteers were scanned with both modes during a cyclic flexion-extension motion of the knee and analysed using the proposed metric. RESULTS: For all hole sizes and speeds, the cardiac scan mode had significantly lower (p-value

Purpose (1) to assess the influence of internal or external imaging plane inclination on measurement of sulcus angle, trochlear depth, and facet asymmetry on transverse cross-sectional images. (2) to assess the effect of measurement level (height) on these respective parameters. Materials and methods Twenty dry femurs (9 left, 11 right) were imaged with CT. A 3D dataset was obtained from which axial images were reconstructed in the ideal plane without inclination as well as with 8° of medial and lateral inclination. Sulcus angle, trochlear depth, and facet asymmetry were measured on the 3 image sets. In addition, the measurements were performed at 5 mm and 10 mm from the superior margin of the medial trochlear facet. Statistical analysis consisted of Wilcoxon test and calculation of measurement variation. Results There were no statistically significant differences between the indicated measurements on the reference set compared to medial or lateral inclination. All measurements were significantly different depending on measurement height. Conclusion Medial or lateral inclination in the transverse imaging plane of 8 ° does not influence the values of typical parameters used for assessment of trochlear dysplasia. The measurement height has a significant influence, and a consensus should be found as to which is the optimal measurement height.

The lens of the eye can be damaged by ionising radiation, so individuals whose eyes are exposed to radiation during their work may need to protect their eyes from exposure. Lead glasses are widely available, but there are questions about their efficiency in providing eye protection. In this study, Monte Carlo simulations are used to assess the efficiency of lead glasses in protecting the sensitive volume of the eye lens. Two designs currently available for interventional cardiologists are a wraparound (WA) style and ones with flat frontal lenses with side shielding. These designs were considered together with four modifications that would impact upon their efficiency: changing the lead equivalent thickness, adding lead to the frames, elongating the frontal lenses, and adding a closing shield to the bottom rim. For the eye closest to the source, standard models of lead glasses only decrease the radiation reaching the most sensitive region of the eye lens by 22% or less. Varying the lead thickness between 0.4 mm and 0.75 mm had little influence on the protection provided in the simulation of clinical use, neither did adding lead to the frames. Improved shielding was obtained by elongating the frontal lens, which could reduce radiation reaching the eye lens by up to 76%. Glasses with lenses that had a rim at the base, extending towards the face of the user, also provided better shielding than current models, decreasing the dose by up to 80%. In conclusion, elongating the frontal lens of lead glasses, especially of the WA design, could provide a three-fold increase in shielding efficiency and this is still valid for lenses with 0.4 mm lead equivalence.

Coronary CT angiography (CCTA) demonstrated high diagnostic accuracy for detecting coronary artery disease (CAD) and a key role in the management of patients with low-to-intermediate pretest likelihood of CAD. However, the clinical information provided by this noninvasive method is still regarded insufficient in patients with diffuse and complex CAD and for planning percutaneous coronary intervention (PCI) and surgical revascularization procedures. On the other hand, technology advancements have recently shown to improve CCTA diagnostic accuracy in patients with diffuse and calcific stenoses. Moreover, stress CT myocardial perfusion imaging (CT-MPI) and fractional flow reserve derived from CCTA (CT-FFR) have been introduced in clinical practice as new tools for evaluating the functional relevance of coronary stenoses, with the possibility to overcome the main CCTA drawback, i.e. anatomical assessment only. The potential value of CCTA to plan and guide interventional procedures lies in the wide range of information it can provide: a) detailed evaluation of plaque extension, volume and composition; b) prediction of procedural success of CTO PCI using scores derived from CCTA; c) identification of coronary lesions requiring additional techniques (e.g., atherectomy and lithotripsy) to improve stent implantation success by assessing calcium score and calcific plaque distribution; d) assessment of CCTA-derived Syntax Score and Syntax Score II, which allows to select the mode of revascularization (PCI or CABG) in patients with complex and multivessel CAD. The aim of this Consensus Document is to review and discuss the available data supporting the role of CCTA, CT-FFR and stress CT-MPI in the preprocedural and possibly intraprocedural planning and guidance of myocardial revascularization interventions.

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article: Bone Joint J 2021;103-B(5):822–827.

Background Iodine contrast agent (CA) is widely used in cardiac computed tomography (CT). The CA can increase the organ radiation doses due to the photoelectric effect. Purpose To investigate the impact of CA on radiation dose in cardiac CT by comparing the radiation dose between contrast coronary CT angiography (CCTA) and non-contrast calcium scoring CT (CSCT). Material and Methods Radiation doses were computationally calculated for 30 individual patients who received CSCT and CCTA in the same exam session. The geometry and acquisition parameters were modeled in the simulations based on individual patient CT images and acquisitions. Doses in the presence and absence of CA were obtained in the aorta, left ventricle (LV), right ventricle (RV), and myocardial tissue (MT). The dose values were normalized by size-specific dose estimate (SSDE). The dose enhancement factors (DEFSSDE) were calculated as the ratio of doses in CCTA over doses in CSCT. Results Compared to the CSCT scans, doses increase in the CCTA scans in the aorta (DEFSSDE = 2.14 ± 0.20), LV (DEFSSDE = 1.78 ± 0.26), and RV (DEFSSDE = 1.31 ± 0.22). A linear relation is observed between the local CA concentrations and the dose increase in the heart; DEFSSDE = 0.07*I(mg/mL) + 0.80 (R2 = 0.8; p SSDE in the MT (DEFSSDE = 0.96 ± 0.08) showed no noticeable impact of CA on the dose in this tissue. In addition, patient variability in the dose distributions was observed. Conclusion A linear causal relation exists between local CA concentration and increase in radiation dose in cardiac CT. For the same CT exposure, dose to the heart is on average 55% higher in contrast cardiac CT.

BACKGROUND: In significant obstructive coronary artery disease (SOCAD), a mismatch in assessment of severity of coronary artery stenosis may occur between invasive coronary angiography (ICA) and computed tomography (CT) derived fractional flow reserve (FFRCT). The present study aimed to identify the factors giving an FFRCT > 0.80 and leading to an underestimation of coronary artery severity in SOCAD vessels. METHODS: A total of 141 consecutive patients who underwent both CT angiography including FFRCT and ICA, the latter showing >75% coronary artery stenosis were evaluated. Vessels were divided into two groups according to FFRCT at the distal aspect of the vessel: FFRCT > 0.80 (n = 12) and FFRCT ≤ 0.80 (n = 153). Vessel morphology, plaque characteristics, left-ventricular (LV) wall thickness at each site of the myocardium, and LV mass were also assessed. RESULTS: LV myocardium-related parameters including LV wall thickness (base, middle, apex, average, and maximal), LV mass, and LV mass index were higher inFFRCT > 0.80, whereas vessel-related parameters including, vessel morphology and plaque characteristics were not significantly different between >0.80 and 0.80 with an area under the curve of 0.81, and an optimal cut-off value of 66.5 g/m2 (sensitivity 77.8%, specificity 89.6%). CONCLUSIONS: The presence of a high LV mass is a major cause for underestimation of coronary artery severity on FFRCT in SOCAD vessels. LV myocardium-related parameters should be considered when interpreting numerical values of FFRCT.

This study aimed to evaluate the relationship between the brain absorbed dose and personal dosimetry readings in interventional cardiologists. Interventional procedures were replicated using Monte Carlo simulations (MCNP 6) with anthropomorphic phantoms representing both operator and patient. Absorbed doses were evaluated for 10 predefined regions of the operator’s brain as well as for dosemeters at chest and neck level. One beam quality (HVL = 6.2 mm Al) and nine beam projections were considered. A significant bias in the laterality of brain dose was found with doses at the left side of the brain being up to 2.8 times higher compared with the right. The correlation between brain dose and dosemeter reading was found to be dependent on beam projection. Yet, a generalized conversion factor (brain dose normalized by Hp(10)), averaged over all considered beam projections, could be proposed for (retrospective) brain dose estimation from routinely measured dosimetry data.

PURPOSE: To determine the normal thickness and MRI appearance of the Tibialis Posterior Tendon near the navicular insertion in normal volunteers. MATERIALS AND METHODS: By using a 3T MRI system 41 ankles were imaged, and PD weighted images with fat saturation were acquired in the three orthogonal planes. Symptoms of tendon pathology and history of trauma or surgery of the tendon were used as volunteer exclusion criteria. Two different measurement points were determined to evaluate hyperintensity and thickness. Two radiologists assessed the internal signal of the Tibialis Posterior Tendon independently by using axial and coronal images. Tendon hyperintensity was classified from homogenously dark to different degrees of hyperintense signal, where 0 means no internal hyperintensity, 1 - minimal hyperintensity, 2 - moderate and 3 - marked. Correlations between the two observers were obtained by Cohen's kappa. Descriptive statistics were also obtained. RESULTS: Eight men and 13 women (total 21) volunteers, age range 19-43(average 24.7)years were included in the study. At measurement point-1 on the coronal images, observer-1 and observer-2 evaluated hyperintensity (mostly minimal) respectively in 90.5% and 95.3% of tendons with a Cohen's kappa coefficient of 0.701 (moderate agreement) for the right foot and in 60% and 70% of tendons with a Cohen's kappa coefficient of 0.624 (moderate agreement) for the left foot. On axial images both observers assessed hyperintensity (mostly marked) in 100% of the tendons with a coefficient of 0.763 (moderate agreement) for the right foot, and in 95% of tendons with a coefficient of 0.839 (strong agreement) for the left foot. At measurement point-2 on coronal images, both observers rated any degree of hyperintensity in 33.3% of tendons with a coefficient of 1.00 (perfect agreement) for the right foot, in 38.9% of tendons with a coefficient of 0.766 (moderate agreement) for the left foot. On axial images both observers evaluated hyperintensity (mostly minimal) in 100% of tendons with a kappa coefficient of 0.702 (moderate agreement) for the right foot, in 95% of tendons with a coefficient of 0.790 (moderate- to strong agreement) for the left foot. CONCLUSION: The Tibialis Posterior Tendon, near the navicular insertion (navicular tendon and tarsometatarsal tendon), exhibits an apparent thickening and most importantly hyperintensity which should be regarded as a normal finding, and not lead to an erroneous diagnosis of tendinopathy. This observation was almost always the case for the navicular insertion and less so for the tarsometatarsal tendon.

Background: Contrast leakage after arthrography is common. We sought to investigate if immobilization could prevent it. Purpose: The purpose of this study was to determine the effects on contrast extravasation and image quality produced by strict immobilization of the shoulder between arthrography puncture and subsequent MR imaging. Material and methods: Fifty patients underwent shoulder MR arthrography using a standard shoulder puncture in the anteroinferior quadrant. Ten milliliters of contrast mixture of saline, iodinated contrast, and gadolinium contrast was injected by a senior musculoskeletal (MSK) radiologist using a 21G needle. Half of the patients were immediately immobilized using a shoulder sling, and the other half were allowed to move their shoulder and arm freely during the time before MR imaging. MR arthrography was performed with a 3 T system using standard T1 and PD weighted sequences. The MR images were reviewed independently by 2 MSK radiologists and graded for extravasation using a five-point scale (1: none, 2: less than 2 cm, 3: 2-5 cm, 4: 5-10 cm, 5: more than 10 cm) and for image quality using a 5 point scale (1: poor, 5: good). The Pearson correlation was calculated to assess the correlation between leakage and image quality. Results: There was no significant difference in amount of leakage between both groups, and global image quality was found equal in both groups. A negative correlation was found between leakage and quality assessment. Conclusion: This study shows that it cannot be avoided by strict shoulder immobilization and that it negatively affects image quality and interpretation.

BACKGROUND: Computed-tomography (CT) derived fractional-flow-reserve (FFRCT) gradually may decrease from proximal to distal vessels even without apparent coronary artery disease (CAD). It may be unclear whether the decrease in FFRCT at the distal coronal artery is physiological or due to stenosis. We decided to study predictive factors of an FFRCT decline below the pathological value of 0.80 in no-apparent CAD. METHODS: A total of 150 consecutive patients who had both CT angiography coupled to FFRCT analysis and invasive angiogram showing < 20% coronary stenosis were included. Vessels were divided into two groups according to FFRCT at the distal vessel: FFRCT > 0.80 (n = 317) and FFRCT ≤ 0.80 (n = 114). ΔFFRCT was defined as the change in FFRCT from proximal to distal vessel. Vessel morphology (vessel length and lumen volume) and plaque characteristics [low-attenuation plaque volume, intermediate-attenuation (IAP) plaque volume, and calcified plaque volume] were evaluated. RESULTS: FFRCT decreased from proximal to distal for the three major vessels in both FFRCT > 0.80 and FFRCT ≤ 0.80. Compared to FFRCT > 0.80, IAP volume was significantly higher in all three major vessels in FFRCT ≤ 0.80. ΔFFRCT was correlated with vessel length and lumen volume in FFRCT > 0.80, whereas ΔFFRCT was correlated with IAP volume in FFRCT ≤ 0.80. IAP volume above 44.8 mm3 was the strongest predictor of distal FFRCT of ≤ 0.80. CONCLUSIONS: The presence of IAP is a major predictor of gradual decrease of FFRCT below 0.80 in no-apparent CAD vessels. Vessel morphology and plaque characteristics should be considered when interpreting FFRCT.

Dynamic computer tomography (CT) is an emerging modality to analyze in-vivo joint kinematics at the bone level, but it requires manual bone segmentation and, in some instances, landmark identification. The objective of this study is to present an automated workflow for the assessment of three-dimensional in vivo joint kinematics from dynamic musculoskeletal CT images. The proposed method relies on a multi-atlas, multi-label segmentation and landmark propagation framework to extract bony structures and detect anatomical landmarks on the CT dataset. The segmented structures serve as regions of interest for the subsequent motion estimation across the dynamic sequence. The landmarks are propagated across the dynamic sequence for the construction of bone embedded reference frames from which kinematic parameters are estimated. We applied our workflow on dynamic CT images obtained from 15 healthy subjects on two different joints: thumb base (n = 5) and knee (n = 10). The proposed method resulted in segmentation accuracies of 0.90 ± 0.01 for the thumb dataset and 0.94 ± 0.02 for the knee as measured by the Dice score coefficient. In terms of motion estimation, mean differences in cardan angles between the automated algorithm and manual segmentation, and landmark identification performed by an expert were below 1°. Intraclass correlation (ICC) between cardan angles from the algorithm and results from expert manual landmarks ranged from 0.72 to 0.99 for all joints across all axes. The proposed automated method resulted in reproducible and reliable measurements, enabling the assessment of joint kinematics using 4DCT in clinical routine.

Background In significant obstructive coronary artery disease (SOCAD), a mismatched assessment of the severity of coronary artery stenosis may occur between invasive coronary angiography and computed tomography (CT) derived fractional flow reserve (FFRCT). The exact mechanisms of unexpected underestimation of FFRCT remain unknown. Purpose The aims of this study are (1) to clarify the mechanisms of underestimation on FFRCT; and (2) to identify the predictive factors of FFRCT underestimation above the value of 0.80 in SOCAD vessels. Methods A total of 1160 outpatients who underwent CT angiography (CTA) with FFRCT analysis for suspected coronary artery disease (CAD) between January 2017 and June 2020 were evaluated. Among them, 141 consecutive patients who had both CTA coupled to FFRCT analysis and invasive angiogram showing >75% coronary stenosis were included for analysis. Vessels were divided into two groups according to FFRCT at the distal vessel: FFRCT >0.80 (n=12) and FFRCT ≤0.80 (n=153). Vessel-related parameters, including vessel morphology (vessel length and lumen volume) and plaque components (non-calcified plaque volume and calcified plaque volume) and left ventricular (LV) myocardial-related parameters, including LV wall thickness at each site of the myocardium, and LV mass were evaluated semi-automatically. Results Vessel morphology and plaque components did not differ between FFRCT >0.80 and ≤0.80, whereas LV wall thickness (average; 10.7±2.7 vs. 8.4±1.6 mm, and maximal; 13.5±3.0 vs. 10.6±1.8 mm, all p value 0.80. Next, we investigated the parameters that correlated with FFRCT. Of all, vessel morphology and plaque components were not related to FFRCT, whereas maximal LV wall thickness, r=0.24, p=0.01; LV mass, r=0.19. p=0.04; and LV mass index, r=0.30, p=0.001) correlated with FFRCT. In the vessels showing FFRCT >0.80, only LV mass (r=0.84, p=0.005) and LV mass index (r=0.67, p=0.047) correlated with FFRCT. (Figure 1). LV mass index was the strongest predictor of a distal FFRCT of >0.80 with the area under curve (AUC) 0.81, 95% CI 0.62 – 1.00, P Conclusions FFRCT is affected not by vessel-related parameters but LV myocardial-related parameters in SOCAD. The presence of an excessive LV mass is a major predictor of underestimation of FFRCT in SOCAD vessels. LV myocardial-related parameters should be considered when interpreting numerical values of FFRCT to avoid the possibility of overlooked SOCAD. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

4-Dimensional computed tomography (4DCT) for the detection of (an) enlarged parathyroid(s) is a commonly performed examination in the management of primary hyperparathyroidism. In our center, we introduced a high-frequency multiphase 4DCT protocol obtaining 16 phases, including 11 different arterial phases. Exposure to this multiphase 4DCT technique is similar to that for classic helical 4DCT. In this pictorial essay we reconstructed our multiphase 4DCT series in the manner of a classic helical 4DCT and compare both techniques. We illustrate how multiphase 4DCT may aid in the detection of parathyroid adenomas. We found 17 out of 19 lesions demonstrating a type A pattern of enhancement, therefore suggesting this pattern could be more prevalent than previously thought. Some parathyroid adenomas may be mistaken for enlarged lymph nodes using classic 4DCT whereas high-frequency multiphase 4DCT can detect a temporary rise in enhancement, thus suggesting the lesions in question to be of parathyroid origin. Smaller lesions may prove more obvious as the difference in enhancement between parathyroid and thyroid can become more prominent. Key Point Using high-frequency multiphase 4DCT an arterial phase with maximum enhancement of parathyroid tissue can be defined. This phase may aid in the detection of parathyroid adenomas.

PURPOSE: To investigate the contrast media iodine dose dependency of radiation-induced DNA double-strand breaks (DSBs) during a coronary computed tomography angiography (CCTA) scan. METHODS: This prospective patient study was approved by the ethical committee. Between November 2018 and July 2019, 50 patients (31 males and 19 females, mean age 64 years) were included in the study, 45 CCTA and five noncontrast-enhanced (NCE) cardiac computed tomography (CT) patients. A single-heartbeat scan protocol with a patient-tailored contrast media injection protocol was used, administering a patient-specific iodine dose. DNA double-strand breaks were quantified using a γH2AX foci assay on peripheral blood lymphocytes. The net amount of γH2AX/cell was normalized to the individual patient CT dose by the size-specific dose estimate (SSDE). Correlation between the administered and blood-iodine dose and the SSDE normalized amount of DNA DSBs was investigated using a Pearson correlation test. RESULTS: CCTA patients were scanned with a mean CTDIvol of 10.6 ± 5.6 mGy, corresponding to a mean SSDE of 11.3 ± 5.3 mGy while the NCE cardiac CT patients were scanned with a mean CTDIvol of 6.00 ± 1.8 mGy, corresponding to a mean SSDE of 6.6 ± 2.7 mGy. The administered iodine dose ranged from 16.5 to 34.0 gI in the CCTA patients, resulting in a blood-iodine dose range from 5.1 to 15.0 gI in the exposed blood volume. A significant linear relationship (r = 0.79, p-value < 0.001) was observed between the blood iodine dose and SSDE normalized radiation-induced DNA DSBs. A similar significant linear relationship (r = 0.62, p-value < 0.001) was observed between the administered iodine dose and SSDE normalized radiation-induced DNA DSBs. CONCLUSIONS: This study shows that contrast media iodine dose increases the level of radiation-induced DNA DSBs in peripheral blood lymphocytes in a linear dose-dependent manner with CCTA. Importantly, the level of DNA DSBs can be reduced by lowering the administered iodine dose.

PURPOSE: To assess normal distribution of fluid in the tendon sheaths of the ankle. METHODS: 21 healthy volunteers were evaluated. Bilateral ankle MRI was performed on a 3T unit with PD-weighted images with fat saturation. The images were interpreted by two radiologists separately, and the short-axis dimension of fluid amount was measured. Bland-Altman plots and correlation plots were used to assess consistency between readers. RESULTS: There were 13 men and 8 women. The mean age was 24.7 years. Fluid in the retromalleolar part of the peroneus longus was seen in three ankles of three volunteers and in the inframalleolar part in three ankles of three volunteers. Fluid in the retromalleolar part of the peroneus brevis was seen in four ankles of three volunteers and in the inframalleolar part in three ankles of two volunteers. Fluid in the retromalleolar part of the tibialis posterior was seen in 37 ankles of 20 volunteers and in the inframalleolar part in 38 ankles of 21 volunteers Fluid in the retromalleolarpart of the flexor digitorum was seen in 14 ankles of eight volunteers and in the inframalleolar part in 11 ankles of eight volunteers Fluid in the retromalleolar part of the flexor hallucis longus was seen in 23 ankles of 16 volunteers and in the inframalleolar part in 17 ankles of 11 volunteers. CONCLUSION: Fluid is common in the retro- and inframalleolar parts of the medial tendons. Fluid is virtually absent in the peroneal tendons and anterior tendon sheaths in normal volunteers.

The objective of the current study was to explore the potential of dynamic computed tomography to detect kinematic changes, induced by sequential sectioning of the lateral collateral ligaments of the ankle, during full motion sequence of the talocrural joint. A custom-made device was used to induce cyclic controlled ankle inversion movement in one fresh frozen cadaver leg. A 256-slice CT scanner was used to investigate four different scenarios. Scenario 1 with all ligaments intact was first investigated followed by sequential section of the anterior talo-fibular ligament (Scenario 2), the calcaneo-fibular ligament (Scenario 3) and posterior talo-fibular ligament (Scenario 4). Off-line image processing based on semi-automatic segmentation and bone rigid registration was performed. Motion parameters such as translation, rotational angles and orientation and position of the axis of rotation were calculated. Differences between scenarios were calculated. Progressive increase of cranio-caudal displacement up to 3.9 mm and flexion up to 10° compared to Scenario 1 were reported. Progressive changes in orientation (up to 20.6°) and position (up to 4.1 mm) of the axis of rotation were also shown. Estimated effective dose of 0.005 mSv (1.9 mGy CTDIvol) was reported. This study demonstrated that kinematic changes due to the absence of ligament integrity can be detected with 4DCT with minimal radiation exposure. Identifying abnormal kinematic patterns could have future application in helping clinicians to choose patients’ optimal treatment. Therefore, further studies with bigger in vitro sample sizes and consequent investigations in vivo are recommended to confirm the current findings.

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article

Purpose: Tendon pathology around the hip is a common entity. The aim of this study was to detect tendon abnormalities around the hip in a population of asymptomatic volunteers. Materials and methods: Fifty volunteers (100 hips) referred for non-musculoskeletal conditions were evaluated with an additional coronal STIR-weighted MRI imaging on a 1.5 MR unit. This group was composed of 27 women and 23 men with a mean age of 52 (19-91 years). The images were interpreted independently by 2 musculoskeletal radiologists. All tendons around the hip were given a score from 0 to 4, with a score 0 corresponding to no abnormality, score 1 to signal alteration around the tendon, score 2 to minimal signal abnormality in the tendon, score 3 partial tear and score 4 complete rupture. The trochanteric bursa was also evaluated and its size was measured. It was also given a score from 0 to 3 (0: no abnormality, 1: slight hypersignal, 2: bursitis < 10 mm, 3: bursitis ≥ 10 mm). Results: High intratendinous signal was commonly found at the joined insertion of biceps femoris and semitendinosus (18% L, 20% R), the semimembranosus (24% L, 20% R), gluteus minimus (6% L, 11% R) and rectus femoris (9% L, 3% R). A small trochanteric bursa was seen in 33% of the volunteers on the left side and 32% on the right side. The interobserver correlation was very good with an intraclass correlation coefficient of 0.79 (CI: 0.74-0.85). Conclusion: Slight signal alterations might be found in the insertions of the rectus femoris, hamstrings and gluteus minimus tendons. A small to moderate trochanteric bursitis might also be seen. This suggests that care should be taken when interpreting MR scans to attribute symptoms to these findings.