Agreement between single plane and biplane derived angiographic fractional flow reserve in patients with intermediate coronary artery stenosis.

Fractional flow reserve (FFR) is often used to evaluate the physiological severity of intermediate coronary stenoses, but less-invasive assessment methods are desirable. We evaluated the feasibility of angiographic FFR (angioFFR) calculated from two projections acquired simultaneously by a biplane C-arm system and angioFFR calculated from two projections acquired independently by one plane of the same biplane C-arm system. AngioFFR was validated against FFR in terms of detection of hemodynamically relevant coronary artery stenoses. Twenty-two Patients who underwent angiography and FFR for coronary artery disease were included. We used a non-commercial prototype to calculate biplane angioFFR for 22 vessels (19 LAD, 1 LCx, 2 RCA) and single plane angioFFR for 17 of the same 22 vessels. FFR < 0.8 was measured in 8 vessels. The Pearson correlation coefficients with FFR were 0.55 for single plane angioFFR and 0.61 for biplane angioFFR and the diagnostic accuracies were 88% (95% CI 73-100%) for single plane angioFFR and 86% (95% CI 72-100%) for biplane angioFFR. Bland-Altman plots revealed that compared with FFR, the limits of agreement for single plane angioFFR were - 0.07 to 0.19 (mean difference 0.06, p = 0.002) and the limits of agreement for biplane FFR were - 0.09 to 0.15 (mean difference 0.03, p = 0.03). In conclusion, angioFFR calculated from single or biplane acquisitions by a biplane C-arm is feasible and may evolve to a tool for less invasive imaging-based assessment of myocardial ischemia.

Intraoperative cone-beam CT with metal artifact reduction for assessment of the electrode position and the intracranial structures during deep brain stimulation procedure.

BACKGROUND: In deep brain stimulation (DBS) for Parkinson's disease (PD), the clinical outcome largely depends on the appropriate position of the electrode implanted in the targeted structure. In intraoperative cone-beam computed tomography (CT) performed for the evaluation of the electrode position, the metal artifact induced by the implanted electrode can prevent the precise localization of the electrode. Metal artifact reduction (MAR) techniques have been recently developed that can dramatically improve the visualization of objects by reducing metal artifacts after performing cone-beam CT. Hence, in this case series, we attempted to clarify the usefulness and accuracy of intraoperative cone-beam CT with MAR (intraCBCTwM) by comparing with both intraoperative cone-beam CT without MAR (intraCBCTwoM) and conventional postoperative CT (post-CT) for the assessment of the implanted electrode position and the intracranial structures during DBS procedures. METHODS: Between November 2019 and December 2020, 10 patients with PD who underwent DBS at our institution were recruited, and the images of 9 patients (bilateral: n = 8, unilateral: n = 1) were analyzed. The artifact index (AI) in intraCBCTwM or intraCBCTwoM, and conventional post-CT were retrospectively assessed using the standard deviation of the region-of-interest around the implanted electrodes and background noise. Additionally, the Euclidean distances gap of electrode tip based on post-CT in each fusion image was compared between intraCBCTwM and intraCBCTwoM. RESULTS: The AI was significantly lower in intraCBCTwM than in intraCBCTwoM (P < 0.01). The mean Euclidean distance between the tip of the electrode in intraCBCTwM and in post-CT was significantly shorter compared to that in intraCBCTwoM (P < 0.05). CONCLUSIONS: The results reported here suggest that intraCBCTwM is a more useful and accurate method than intraCBCTwoM to assess the implanted electrode position and intracranial structures during DBS.

Diagnostic performance of intraoperative cone beam computed tomography compared with postoperative magnetic resonance imaging for detecting hemorrhagic transformation after endovascular treatment following large vessel occlusion.

OBJECTIVES: Early detection of hemorrhagic transformation (HT) in patients with large vessel occlusion (LVO) after endovascular treatment is important for postoperative patient management. We investigated the diagnostic performance of intraoperative cone beam computed tomography (CBCT) with reference standard magnetic resonance imaging (MRI) for detecting HT. MATERIALS AND METHODS: Consecutive patients with LVO treated by endovascular treatment who underwent intraoperative CBCT and postoperative MRI were included. Two observers evaluated all images for the presence of HT. Sensitivity and specificity for detecting HT were calculated with MRI as reference standard. The observers classified HT according to the European Cooperative Acute Stroke Study (ECASS). Inter-method and inter-rater agreement for the detection of HT and for the ECASS classification were assessed using kappa or weighted Brennan-Prediger (wBP) statistics. RESULTS: Images of 106 procedures (94 for anterior circulation) were analyzed. The sensitivity and specificity for detecting HT on CBCT were 0.77 and 0.83, respectively, for all procedures and 0.83 and 0.8, respectively, for anterior circulation. The inter-method agreement for HT detection (κ = 0.63 overall, κ = 0.69 anterior circulation) and ECASS classification (wBP = 0.67 overall, wBP = 0.77 anterior circulation) were substantial. The inter-rater agreement for HT detection (κ = 0.87 overall, κ = 0.85 anterior circulation) and for ECASS classification (wBP = 0.95 overall, wBP = 0.92 anterior circulation) were almost perfect. CONCLUSIONS: The diagnostic performance of CBCT for the detection of HT in stroke patients treated for LVO was acceptable with excellent inter-rater agreement. Intraoperative CBCT may be useful to trigger early interventions if HT is detected, although detailed classifications of HT may be difficult.

Rupture Risk of Small Unruptured Intracranial Aneurysms in Japanese Adults.

Background and Purpose- Therapeutic decision making for small unruptured intracranial aneurysms (<10 mm) is difficult. We aimed to develop a rupture risk model for small intracranial aneurysms in Japanese adults, including clinical, morphological, and hemodynamic parameters. Methods- We analyzed 338 small unruptured aneurysms; 35 ruptured during the observation period, and 303 remained stable. Clinical, morphological, and hemodynamic parameters were considered. Computational fluid dynamics was used to calculate hemodynamic parameters based on computed tomography images of all aneurysms in their unruptured state. Differences between the ruptured and unruptured groups were tested by the Mann-Whitney U or Fisher exact tests. Multivariate logistic regression was applied to obtain a rupture risk model. Its predictive ability was investigated by receiver operating characteristic analysis. Results- The risk model revealed that rupture may be more likely to in younger patients (odds ratio [OR], 0.92 for each age increase of 1 year [95% CI, 0.88-0.96] P<0.001) with multiple aneurysms (OR, 2.58 [95% CI, 1.07-6.19] P=0.03), located at a bifurcation (OR, 5.45 [95% CI, 1.87-15.85] P=0.002), with a bleb (OR, 4.09 [95% CI, 1.42-11.79] P=0.009), larger length (OR, 1.91 for each increase of 1 mm [95% CI, 1.42-2.57] P<0.001), and lower pressure loss coefficient (OR, 0.33 for each decrease of 1 unit [95% CI, 0.14-0.77] P=0.01). The sensitivity, specificity, and area under the curve were 0.800, 0.752, and 0.826 (95% CI, 0.739-0.914) respectively. Conclusions- Younger age, presence of multiple aneurysms, location at a bifurcation, presence of a bleb, larger length, and lower pressure loss coefficient were identified as risk factors for rupture of small intracranial aneurysms. The risk model should be validated in further studies.

4D Digital Subtraction Angiography for the Temporal Flow Visualization of Intracranial Aneurysms and Vascular Malformations.

PURPOSE: To assess the benefit and radiation dose of four-dimensional (4D) digital subtraction angiography (DSA) - a time resolved three-dimensional (3D) DSA application - to evaluate the flow and architecture of aneurysms and vascular malformations. METHODS: All patients with cerebrovascular disease were considered who underwent 4D-DSA at our institution between January 2015 and February 2016. For the aneurysm patients, we evaluated the image quality in terms of the visualization of contrast flow in the aneurysm on a 3-point scale (excellent, fair and poor). Interrater agreement between two raters was estimated using Cohen's Kappa statistics. For the shunt disease patients, the additional information obtained from the 4D-DSA was described for each disease. The median radiation dose and volume of contrast medium required for the acquisitions were estimated. RESULTS: A total of 173 patients underwent 4D-DSA; 126 intracranial aneurysms, 10 arteriovenous malformations (AVM), 15 dural arteriovenous fistula (dAVF) and 22 other diseases. For aneurysm patients, excellent and fair visualization of the intra-aneurysmal flow was observed in 27.7%, 72.3%, and excellent (κ = 0.9) agreement between the raters was found. For AVM and dAVF patients, 4D-DSA clarified the complex vasculature by viewing the discrete time phase of contrast filling. Median radiation dose for intracranial lesions was 79.6 mGy for 6s 4D-DSA, and 175 mGy for 12s 4D-DSA. The median amount of contrast medium used was 18.0 ml for 6s 4D-DSA and 21.0 ml for 12s 4D-DSA. CONCLUSIONS: 4D-DSA provided additional information regarding intra-aneurysmal flow and contributed to detect different component of nidus or shunt points.

Modified calcium subtraction in dual-energy CT angiography of the lower extremity runoff: impact on diagnostic accuracy for stenosis detection.

OBJECTIVES: To investigate the diagnostic accuracy of a modified three-material decomposition calcium subtraction (CS) algorithm for the detection of arterial stenosis in dual-energy CT angiography (DE-CTA) of the lower extremity runoff compared to standard image reconstruction, using digital subtraction angiography (DSA) as the reference standard. METHODS: Eighty-eight patients (53 males; mean age, 65.9 ± 11 years) with suspected peripheral arterial disease (PAD) who had undergone a DE-CTA examination of the lower extremity runoff between May 2014 and May 2015 were included in this IRB-approved, HIPAA-compliant retrospective study. Standard linearly blended and CS images were reconstructed and vascular contrast-to-noise ratios (CNR) were calculated. Two independent observers assessed subjective image quality using a 5-point Likert scale. Diagnostic accuracy for ≥ 50% stenosis detection was analyzed in a subgroup of 45 patients who had undergone additional DSA. Diagnostic accuracy parameters were estimated with a random-effects logistic regression analysis and compared using generalized estimating equations. RESULTS: CS datasets showed higher CNR (15.3 ± 7.3) compared to standard reconstructions (13.5 ± 6.5, p < 0.001). Both reconstructions showed comparable qualitative image quality scores (CS, 4.64; standard, 4.57; p = 0.220). Diagnostic accuracy (sensitivity, specificity, positive and negative predictive values) for CS reconstructions was 96.5% (97.5%, 95.6%, 90.9%, 98.1) and 93.1% (98.8%, 90.4%, 82.3%, 99.1%) for standard images. CONCLUSIONS: A modified three-material decomposition CS algorithm provides increased vascular CNR, equivalent qualitative image quality, and greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff on DE-CTA compared with standard image reconstruction. KEY POINTS: • Calcified plaques may lead to overestimation of stenosis severity and false positive results, requiring additional invasive digital subtraction angiography (DSA). • A modified three-material decomposition algorithm for calcium subtraction provides greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff compared with standard image reconstruction. • The application of this algorithm in patients with heavily calcified vessels may be helpful to potentially reduce inconclusive CT angiography examinations and the need for subsequent invasive DSA.

Diagnostic accuracy of low and high tube voltage coronary CT angiography using an X-ray tube potential-tailored contrast medium injection protocol.

OBJECTIVES: To compare the diagnostic accuracy between low-kilovolt peak (kVp) (≤ 100) and high-kVp (> 100) third-generation dual-source coronary CT angiography (CCTA) using a kVp-tailored contrast media injection protocol. METHODS: One hundred twenty patients (mean age = 62.6 years, BMI = 29.0 kg/m2) who underwent catheter angiography and CCTA with automated kVp selection were separated into two cohorts (each n = 60, mean kVp = 84 and 117). Contrast media dose was tailored to the kVp level: 70 = 40 ml, 80 = 50 ml, 90 = 60 ml, 100 = 70 ml, 110 = 80 ml, and 120 = 90 ml. Contrast-to-noise ratio (CNR) was measured. Two observers evaluated image quality and the presence of significant coronary stenosis (> 50% luminal narrowing). RESULTS: Diagnostic accuracy (sensitivity/specificity) with ≤ 100 vs. > 100 kVp CCTA was comparable: per patient = 93.9/92.6% vs. 90.9/92.6%, per vessel = 91.5/97.8% vs. 94.0/96.8%, and per segment = 90.0/96.7% vs. 90.7/95.2% (all P > 0.64). CNR was similar (P > 0.18) in the low-kVp vs. high-kVp group (12.0 vs. 11.1), as ws subjective image quality (P = 0.38). Contrast media requirements were reduced by 38.1% in the low- vs. high-kVp cohort (53.6 vs. 86.6 ml, P < 0.001) and radiation dose by 59.6% (4.3 vs. 10.6 mSv, P < 0.001). CONCLUSIONS: Automated tube voltage selection with a tailored contrast media injection protocol allows CCTA to be performed at ≤ 100 kVp with substantial dose reductions and equivalent diagnostic accuracy for coronary stenosis detection compared to acquisitions at > 100 kVp. KEY POINTS: • Low-kVp coronary CT angiography (CCTA) enables reduced contrast and radiation dose. • Diagnostic accuracy is comparable between ≤ 100 and > 100 kVp CCTA. • Image quality is similar for low- and high-kVp CCTA. • Low-kVp image acquisition is facilitated by automated tube voltage selection. • Tailoring contrast injection protocols to the automatically selected kVp-level is feasible.

Hemodynamic and morphological differences in cerebral aneurysms between before and after rupture.

OBJECTIVE: Although it has been proposed that aneurysm morphology is different after rupture, detailed research of the morphological changes using 3D imaging acquired before and after rupture has not been conducted because of the difficulty of data collection. Similarly, hemodynamic changes due to morphological alterations after rupture have not been analyzed. The aim of this study was to investigate the changes in morphology and hemodynamics observed after aneurysm rupture. METHODS: For 21 cerebral aneurysms (21 patients) that ruptured during observation, 3D geometry of the aneurysms and parent arteries were reconstructed based on the angiographic images before and after their rupture. In addition, using the reconstructed geometry, blood flow was simulated by computational fluid dynamics (CFD) analysis. Morphological and hemodynamic parameters were calculated both before and after rupture, and their changes from before to after were compared. RESULTS: In the morphological parameters, statistically significantly higher values were observed after rupture in height (before: 5.5 ± 2.1 mm, after: 6.1 ± 2.0 mm; p < 0.0001), aspect ratio (p = 0.002), aneurysm volume (p = 0.04), and undulation index (p = 0.005). In terms of hemodynamic changes, the mean normalized wall shear stress (NWSS) decreased significantly (before: 5.4 × 10-1 ± 2.9 × 10-1, after: 4.4 × 10-1 ± 2.8 × 10-1; p < 0.001) as well as the other NWSS parameters, including maximum and minimum NWSS, which were associated with stagnant flow due to the morphological changes after rupture. CONCLUSIONS: Aneurysm morphology was found to change after rupture into an elongated and irregular geometry, accompanied by an increase in aneurysm volume. These morphological changes were also associated with statistically significant hemodynamic alterations that produced low wall sheer stress by stagnant flow. The authors' results also provide the opportunity to explore and develop a risk evaluation method for aneurysm rupture based on prerupture morphology and hemodynamics by further exploration in this direction.

Three-dimensional fusion imaging to assess apposition of low-profile visualized intraluminal support stent for intracranial aneurysm coiling.

Objective: To investigate on three-dimensional (3D) fusion images the apposition of low-profile visualized intraluminal support (LVIS) stents in intracranial aneurysms after treatment and assess inter-rater reliability. Materials and methods: Records of all patients with unruptured intracranial aneurysms who were treated with the LVIS stent were retrospectively accessed and included in this study. Two neurosurgeons evaluated the presence of malapposition between the vessel walls and the stent trunk (crescent sign) and the vessel wall and the stent edges (edge malappostion) on 3D fusion images. These images were high-resolution cone-beam computed tomography images of the LVIS stent fused with 3D-digital subtraction angiography images of the vessels. Associations between malapposition and aneurysm location were assessed by Fisher's exact test, and inter-rater agreement was estimated using Cohen's kappa statistic. Results: Forty consecutive patients were included. In all patients, 3D fusion imaging successfully visualized the tantalum helical strands and the closed-cell structure of the nitinol material of the low-profile visualized intraluminal support. A crescent sign was observed in 27.5 % and edge malapposition in 47.5 % of the patients. Malapposition was not significantly associated with location (p = 0.23 crescent sign, p = 0.07 edge malapposition). Almost perfect (κ = 0.88) and substantial (κ = 0.76) agreements between the two raters were found for the detection of crescent signs and edge appositions, respectively. Conclusions: 3D fusion imaging provided clear visualization of the LVIS stent and parent arteries, and could detect malapposition with excellent inter-rater reliability. This technique may provide valuable guidance for surgeons in determining postoperative management.

Experimental study using phantom models of cerebral aneurysms and 4D-DSA to measure blood flow on 3D-color-coded images.

BACKGROUND: The current 3D-iFlow application can only measure the arrival time of contrast media through intensity values. If the flow rate could be estimated by 3D-iFlow, patient-specific hemodynamics could be determined within the scope of normal diagnostic management, eliminating the need for additional resources for blood flow rate estimation. OBJECTIVE: The aim of this study is to develop and validate a method for measuring the flow rate by data obtained from 3D-iFlow images - a prototype application in Four-dimensional digital subtraction angiography (4D-DSA). METHODS: Using phantom model and experimental circuit with circulating glycerin solution, an equation for the relationship between contrast media intensity and flow rate was developed. Applying the equation to the aneurysm phantom models, the derived flow rate was evaluated. RESULTS: The average errors between the derived flow rate and setting flow rate became larger when the glycerin flow and the X-rays from the X-ray tube of the angiography system were parallel to each other or when the measurement point included overlaps with other contrast enhanced areas. CONCLUSION: Although the error increases dependent on the imaging direction and overlap of contrast enhanced area, the developed equation can estimate the flow rate using the image intensity value measured on 3D-iFlow based on 4D-DSA.

Virtual coil images can optimize the visualization of the neckline of intracranial aneurysms during coil embolization: A technical note.

Background: During coil embolization of intracranial aneurysms, the aneurysmal neck needs to be evaluated because coil protrusion into the parent artery may lead to ischemic complications. However, the neck cannot always be clearly visualized due to the limitation of the angiography system and due to the structure of the aneurysm. As a visual aid, we propose a color-coded fusion imaging method that generates "virtual coil" images using preoperative three-dimensional digital subtraction angiography (3D-DSA) images. Case Description: Coil embolization for intracranial aneurysms was performed using the working angles determined from the preoperative 3D-DSA. The aneurysms were located at the middle cerebral artery, anterior communicating artery (A-com), and posterior communicating artery (P-com). The A-com and P-com aneurysms were recurrent. During the later phase of the procedure, physicians could not judge whether coils protruded into the parent artery on two-dimensional digital subtraction angiography (2D-DSA) images because an optimal working angle could not be realized. Virtual coil images were displayed on the angiography system's monitor to show the expected completed embolization, which could be compared to the current 2D-DSA images as a visual aid. Conclusion: Virtual coil images can provide visual aid to the treating physician during aneurysm coil embolization, which is useful when an accurate working angle cannot be reached.

Intraoperative Cone-Beam Computed Tomography Assessment of Spinal Pedicle Screws Placement Precision Is in Full Agreement with Postoperative Computed Tomography Assessment.

OBJECTIVE: To assess agreement between pedicle screw placement evaluated on postoperative computed tomography (CT) and on intraoperative cone-beam CT (CBCT) and compare procedure characteristics when using first-generation and second-generation robotic C-arm systems in the hybrid operating room. METHODS: All patients who received pedicle screws for spinal fusion at our institution between June 2009 and September 2019 and underwent intraoperative CBCT and postoperative CT were included. The CBCT and CT images were reviewed by 2 surgeons to assess the screw placement using the Gertzbein-Robbins and the Heary classifications. Intermethod agreement of screw placement classifications as well as interrater agreement were assessed using Brennan-Prediger and Gwet agreement coefficients. Procedure characteristics using first-generation and second-generation generation robotic C-arm systems were compared. RESULTS: Fifty-seven patients were treated with 315 pedicle screws at thoracic, lumbar, and sacral levels. No screw had to be repositioned. On CBCT, accurate placement was found for 309 screws (98.1%) using the Gertzbein-Robbins classification and 289 (91.7%) using the Heary classification and on CT, these were 307 (97.4%) and 293 (93.0%), respectively. Intermethod between CBCT and CT and interrater agreements between the 2 raters were almost perfect (>0.90) for all assessment. There were no significant differences in mean radiation dose (P = 0.83) and fluoroscopy time (P = 0.82), but length of surgery using the second-generation system was estimated at 107.7 minutes (95% confidence interval, 31.9-183.5 minutes; P = 0.006) shorter. CONCLUSIONS: Intraoperative CBCT provides accurate assessment of pedicle screw placement and enables intraoperative repositioning of misplaced screws.

An AI-Powered Clinical Decision Support System to Predict Flares in Rheumatoid Arthritis: A Pilot Study.

Treat-to-target (T2T) is a main therapeutic strategy in rheumatology; however, patients and rheumatologists currently have little support in making the best treatment decision. Clinical decision support systems (CDSSs) could offer this support. The aim of this study was to investigate the accuracy, effectiveness, usability, and acceptance of such a CDSS-Rheuma Care Manager (RCM)-including an artificial intelligence (AI)-powered flare risk prediction tool to support the management of rheumatoid arthritis (RA). Longitudinal clinical routine data of RA patients were used to develop and test the RCM. Based on ten real-world patient vignettes, five physicians were asked to assess patients' flare risk, provide a treatment decision, and assess their decision confidence without and with access to the RCM for predicting flare risk. RCM usability and acceptance were assessed using the system usability scale (SUS) and net promoter score (NPS). The flare prediction tool reached a sensitivity of 72%, a specificity of 76%, and an AUROC of 0.80. Perceived flare risk and treatment decisions varied largely between physicians. Having access to the flare risk prediction feature numerically increased decision confidence (3.5/5 to 3.7/5), reduced deviations between physicians and the prediction tool (20% to 12% for half dosage flare prediction), and resulted in more treatment reductions (42% to 50% vs. 20%). RCM usability (SUS) was rated as good (82/100) and was well accepted (mean NPS score 7/10). CDSS usage could support physicians by decreasing assessment deviations and increasing treatment decision confidence.

Imaging of ventilation with dual-energy CT during breath hold after single vital-capacity inspiration of stable xenon.

PURPOSE: To assess single-breath-hold technique for ventilation mapping by using dual-energy computed tomography (CT) in phantom experiments and volunteers. MATERIALS AND METHODS: Institutional review board approved this study, and written informed consent was obtained from all volunteers. A rubber bag filled with a mixture of xenon (0%-35.4%) and oxygen was scanned with dual-source dual-energy CT (80 kV and 140 kV with tin [Sn] filter [Sn/140 kV] and 100 kV and Sn/140 kV). A cylinder containing six tubes of identical sizes with different apertures was ventilated once with a mixture of 35% xenon and 65% oxygen and was scanned in dual-energy mode (80 kV and Sn/140 kV). Xenon-enhanced images were derived by using three-material decomposition technique. Four volunteers were scanned twice in dual-energy mode (80 kV and Sn/140 kV) during breath hold after a single vital-capacity inspiration of air (nonenhanced) and of 35% xenon. Xenon-enhanced images were obtained by using two methods: three-material decomposition and subtraction of nonenhanced from xenon-enhanced images. Regression analysis with t and F tests was applied to the data of the rubber bag scans, with the significance level set at .05. RESULTS: Mean pixel values of gas in the bag were linearly related to xenon concentration for all x-ray tube voltages (r(2) = 1.00, P < .00001). Pixel values of the xenon-enhanced images of the tubes were related to their aperture size. Nearly homogeneous (coefficient of variation: 0.22, 0.23, and 0.34) pixel values were found in the lungs of healthy volunteers, with higher pixel values in the trachea and lower pixel values in the bullae. Xenon-enhanced images calculated by using three-material decomposition had better image quality on visual comparison than those calculated by using subtraction. CONCLUSION: Xenon-enhanced dual-energy CT with the single-breath-hold technique could depict ventilation in phantoms and in four volunteers.

Evaluation of cartilage invasion by laryngeal and hypopharyngeal squamous cell carcinoma with dual-energy CT.

PURPOSE: To evaluate the clinical usefulness of dual-energy computed tomography (CT) with weighted-average (WA) images and iodine overlay (IO) images in the evaluation of laryngeal cartilage invasion in patients with laryngeal and hypopharyngeal squamous cell carcinoma (SCC). MATERIALS AND METHODS: The institutional review board approved this retrospective study, and written comprehensive consent was obtained from all patients. Seventy-two consecutive patients underwent 128-section dual-source dual-energy CT to stage laryngeal (n=27) or hypopharyngeal (n=45) cancer. Three observers who were blinded to the patients' clinical histories and histopathologic findings evaluated cartilage invasion on WA images alone or in combination with IO images (nonossified cartilages were selectively evaluated on IO images) by using a five-point scale. Thirty of the 72 patients (42%) underwent surgery, and findings from histopathologic examination in those patients were used as the standard of reference for the evaluation of diagnostic performance with receiver operating characteristic (ROC) curve analysis and in terms of sensitivity and specificity. Interobserver reproducibility was calculated with κ statistics. RESULTS: For thyroid cartilage, the area under the ROC curve (AUC) of the WA plus IO images was marginally larger than that for WA images alone (AUC=0.957 vs 0.870, respectively; P=.075). The specificity of WA plus IO images was significantly superior to that of WA images alone (96% vs 70%, respectively; P=.031), with no compromise to the sensitivity (86% for both). For thyroid and cricoid cartilages, the interobserver reproducibility was higher for diagnoses made with WA plus IO images (κ=0.68-0.72 and 0.64-0.79, respectively) than for those made with WA images alone (κ=0.29-0.56 and 0.20-0.64, respectively). CONCLUSION: Combined analysis of WA and IO images obtained with dual-energy CT improves the diagnostic performance and interobserver reproducibility of evaluations of laryngeal cartilage invasion by SCC.

Applying Machine Learning to Determine 25(OH)D Threshold Levels Using Data from the AMATERASU Vitamin D Supplementation Trial in Patients with Digestive Tract Cancer.

Some controversy remains on thresholds for deficiency or sufficiency of serum 25-hydroxyvitamin D (25(OH)D) levels. Moreover, 25(OH)D levels sufficient for bone health might differ from those required for cancer survival. This study aimed to explore these 25(OH)D threshold levels by applying the machine learning method of multivariable adaptive regression splines (MARS) in post hoc analyses using data from the AMATERASU trial, which randomly assigned Japanese patients with digestive tract cancer to receive vitamin D or placebo supplementation. Using MARS, threshold 25(OH)D levels were estimated as 17 ng/mL for calcium and 29 ng/mL for parathyroid hormone (PTH). Vitamin D supplementation increased calcium levels in patients with baseline 25(OH)D levels ≤17 ng/mL, suggesting deficiency for bone health, but not in those >17 ng/mL. Vitamin D supplementation improved 5-year relapse-free survival (RFS) compared with placebo in patients with intermediate 25(OH)D levels (18−28 ng/mL): vitamin D, 84% vs. placebo, 71%; hazard ratio, 0.49; 95% confidence interval, 0.25−0.96; p = 0.04. In contrast, vitamin D supplementation did not improve 5-year RFS among patients with low (≤17 ng/mL) or with high (≥29 ng/mL) 25(OH)D levels. MARS might be a reliable method with the potential to eliminate guesswork in the estimation of threshold values of biomarkers.

Role of patient-specific blood properties in computational fluid dynamics simulation of flow diverter deployed cerebral aneurysms.

BACKGROUND: Hemodynamics and their clinical outcome of cerebral aneurysms treated with flow diverter (FD) stents have thus far been investigated using computational fluid dynamics (CFD) simulations. Although human blood is characterized as a non-Newtonian patientspecific fluid, non-patient-specific blood properties (PSBP) were applied in most extant studies. OBJECTIVE: To investigate the hemodynamic effects caused by PSBPs in aneurysms treated with FD stents. METHODS: We measured blood properties (density and viscosity) for 12 patients who underwent FD stent deployment. We conducted CFD simulations with the measured PSBPs and non-PSBPs quoted from previous studies. The average blood flow velocity and wall shear stress within the aneurysms were calculated and two simulation patterns were compared. RESULTS: The velocity and wall shear stress changed by 2.93% and 3.16% on average, respectively, without an FD stent deployed. Conversely, with the FD stents deployed, the change rates increased to 11.1% and 9.06% on average, respectively. CONCLUSIONS: The change in hemodynamic parameters if PSBPs are considered, may not be negligible when conducting CFD simulations of FD stent deployed aneurysms To obtain an adequate hemodynamic environment for cerebral aneurysms with FD stents deployed, it is recommended to use PSBPs for CFD simulations.

Extraction of patient-specific boundary conditions from 4D-DSA and their influence on CFD simulations of cerebral aneurysms.

We developed a new technique for extracting patient-specific inflow conditions, such as the pulse cycle duration and blood flow velocity, from four-dimensional digital subtraction angiography images and experimentally examined its validity. The maximum error between the values extracted by the technique and measured values was 14.3%. We performed blood flow simulations and calculated representative haemodynamic parameters. The maximum differences between the parameters obtained using general and patient-specific inflow conditions were approximately 400%, 150%, and 50% for the velocity, normalised wall shear stress, and pressure loss coefficient, respectively. These results indicate that patient-specific conditions are critical for accurately reproducing aneurysmal haemodynamics.

Development of a Virtual Stent Deployment Application to Estimate Patient-Specific Braided Stent Sizes.

A virtual stent deployment application was developed to estimate the appropriate and patient-specific size of a braided stent for patients who undergo endovascular treatment for intracranial aneurysms. Comparing between the simulated deployed and the actual stents, we evaluated the accuracy of the simulation results. Our results indicated that lengths of the virtual and actual stents matched well despite the actual stent being affected by a geometrical change of the parent artery.Clinical Relevance-Surgeons need to be well-experienced to select an appropriate braided stent size for endovascular treatment of intracranial aneurysms, because the actual length of the deployed stent changes. This simulation will be helpful to make tailor-made surgical planning regardless of the surgeons' individual skill level.

Hemodynamic and Morphologic Factors Related to Coil Compaction in Basilar Artery Tip Aneurysms.

OBJECTIVE: Coil compaction is directly related to the degree of cerebral aneurysmal recanalization. The degree of recanalization (DoR) was quantified by measuring the volume vacated by coil deformation. The purpose of this study was to clarify the hemodynamic and morphologic factors associated with coil compaction. METHODS: Computational fluid dynamics simulations were performed on 28 middle-size (5-10 mm) unruptured basilar artery tip aneurysms. The DoR was measured by comparing the coil mass shape obtained from three-dimensional digital subtraction angiography data immediately after coil embolization and again within 1-2 years of follow-up. Deployed coils were modeled using a virtual coiling technique for computational fluid dynamics simulations. Hemodynamic and morphologic factors to predict the DoR were derived using multiple linear regression. RESULTS: Aneurysmal neck area, the maximum pressure generated on the neck surface after coil embolization, and the high-pressure position on the neck surface predicted DoR with statistic significance (P < 0.001, P < 0.001, P = 0.004, respectively). The DoR tended to increase when the neck area was large, the pressure generated on the coils was high, and the high-pressure position was close to the center of the neck surface. The volume embolization ratio was not statistically relevant for the DoR in the cases of this study. CONCLUSIONS: Coil compaction occurs in cerebral aneurysms with a wide neck, high pressure generated on the coils, and high pressure in the center of the neck surface. Establishing the DoR can contribute to the prediction of recanalization after coil embolization.