Ultra-high-resolution Computed Tomography Research Articles

Ultra-high resolution CT angiography for the assessment of intracranial stents and flow diverters using photon counting detector CT

BackgroundThe patency of intracranial stents may not be reliably assessed with either CT angiography or MR angiography due to imaging artifacts. We investigated the potential of ultra-high resolution CT angiography...

Coronary artery disease detection using deep learning and ultrahigh-resolution photon-counting coronary CT angiography

PurposeThe purpose of this study was to evaluate the diagnostic performance of automated deep learning in the detection of coronary artery disease (CAD) on photon-counting coronary CT angiography (PC-CCTA). Materials and methodsConsecutive patients with suspected CAD who underwent PC-CCTA between January 2022 and December 2023 were included in this retrospective, single-center study. Non-ultra-high resolution (UHR) PC-CCTA images were analyzed by artificial intelligence using two deep learning models (CorEx, Spimed-AI), and compared to human expert reader assessment using UHR PC-CCTA images. Diagnostic performance for global CAD assessment (at least one significant stenosis ≥ 50 %) was estimated at patient and vessel levels. ResultsA total of 140 patients (96 men, 44 women) with a median age of 60 years (first quartile, 51; third quartile, 68) were evaluated. Significant CAD on UHR PC-CCTA was present in 36/140 patients (25.7 %). The sensitivity, specificity, accuracy, positive predictive value), and negative predictive value of deep learning-based CAD were 97.2 %, 81.7 %, 85.7 %, 64.8 %, and 98.9 %, respectively, at the patient level and 96.6 %, 86.7 %, 88.1 %, 53.8 %, and 99.4 %, respectively, at the vessel level. The area under the receiver operating characteristic curve was 0.90 (95 % CI: 0.83–0.94) at the patient level and 0.92 (95 % CI: 0.89–0.94) at the vessel level. ConclusionAutomated deep learning shows remarkable performance for the diagnosis of significant CAD on non-UHR PC-CCTA images. AI pre-reading may be of supportive value to the human reader in daily clinical practice to target and validate coronary artery stenosis using UHR PC-CCTA.

Energy-integrating detector based ultra-high-resolution CT with deep learning reconstruction for the assessment of calcified lesions in coronary artery disease

BackgroundThe aim of this study to compare of the image quality of calcified lesions in coronary artery disease between deep learning reconstruction (DLR) and model-based iterative reconstruction (MBIR) on energy-integrating detector (EID) based ultra-high-resolution CT (UHRCT). MethodsWe performed a phantom study on EID-based UHRCT using a dedicated insert for calcifications and obtained the derivative values for DLR and MBIR. In the clinical study, the derivative values were compared between DLR and MBIR across 73 calcified lesions in 62 patients. Edge sharpness of calcifications and contrast resolution at the coronary lumen side were quantified by the maximum and minimum derivative values. Two radiologists independently analyzed image quality of the calcified lesions using a 5-point Likert scale. ResultsIn the phantom study, the edge sharpness of the 3-mm calcifications on DLR (median, 924 HU/mm; IQR, 580–1741 HU/mm) was significantly higher than on MBIR (median, 835 HU/mm; IQR, 484–1552; p ​< ​0.001). In the clinical study, the image quality of the calcified lesions was significantly better on DLR with significantly reduced reconstruction time (p ​< ​0.001). The contrast resolution at the coronary lumen side on DLR (median, −99.1 HU/mm; IQR, −209 to −34.3 HU/mm) was significantly higher than on MBIR (median, −41.8 HU/mm; IQR, −121 to 22.3 HU/mm, p ​< ​0.001) although the edge sharpness of calcifications was similar between DLR and MBIR (p ​= ​0.794) in the clinical setting. ConclusionEID-based UHRCT reconstructed using DLR represents better image quality of calcified lesions in coronary artery disease compared with MBIR, with significantly reduced reconstruction time.

Artificial Intelligence in CT Diagnosis: Current Status and Future Prospects for Ear Diseases

The human ear, with its complex structures like the ossicular chain, cochlea, and auditory nerve, plays a crucial role in hearing and balance. Common ear diseases, such as hearing loss, tinnitus, facial paralysis and vertigo, affect the quality of life of millions in China. Computed tomography (CT) has seen significant advancements since its introduction to China in 2000. The resolution improves from millimeter to sub-millimeter levels, and further, to 10 μm through bone-dedicated CT technology. The advancements have made CT the preferred method for diagnosing various ear conditions, including congenital malformations, trauma, inflammation, and neoplasm. Artificial intelligence (AI) has brought significant breakthroughs in CT diagnosis. Automatic segmentation of ear structures has dramatically improved with the advent of ultra-high-resolution computed tomography (U-HRCT). AI-driven measurement tools are enhancing the precision and personalization of surgical planning, while deep learning-based anomaly detection is utilized to address the challenges of detecting diverse ear lesions. Furthermore, AI-driven natural language processing and large language models are revolutionizing the generation of radiology reports, providing accurate and standardized diagnostic information. Despite ongoing challenges, the integration of AI into CT is expected to advance the otological field, leading to more precise and personalized treatment for ear diseases.

Coronary CT angiography-based FFR with ultrahigh-resolution photon-counting detector CT: Intra-individual comparison to energy-integrating detector CT

PurposeTo evaluate the feasibility of CT angiography-derived fractional flow reserve (CT-FFR) calculations on ultrahigh-resolution (UHR) photon-counting detector (PCD)-CT series and to intra-individually compare the results with energy-integrating (EID)-CT measurements. MethodProspective patients with calcified plaques detected on EID-CT between April 1st, 2023 and January 31st, 2024 were recruited for a UHR CCTA on PCD-CT within 30 days. PCD-CT was performed using the same or a lower CT dose index and an equivalent volume of contrast media. An on-site machine learning algorithm was used to obtain CT-FFR values on a per-vessel and per-patient basis. For all analyses, CT-FFR values ≤ 0.80 were deemed to be hemodynamically significant. ResultsA total of 34 patients (age: 67.3 ± 6.6 years, 7 women [20.6 %]) were included. Excellent inter-scanner agreement was noted for CT-FFR values in the per-vessel (ICC: 0.93 [0.90–0.95]) and per-patient (ICC: 0.94 [0.88–0.97]) analysis. PCD-CT-derived CT-FFR values proved to be higher compared to EID-CT values on both vessel (0.58 ± 0.23 vs. 0.55 ± 0.23, p < 0.001) and patient levels (0.73 ± 0.23 vs. 0.70 ± 0.22, p < 0.001). Two patients (5.9 %) with hemodynamically significant lesions on EID-CT were reclassified as non-significant on PCD-CT. All remaining participants were classified into the same category with both scanner systems. ConclusionsWhile UHR CT-FFR values demonstrate excellent agreement with EID-CT measurements, PCD-CT produces higher CT-FFR values that could contribute to a reclassification of hemodynamic significance.

A potential usefulness of ultra-high-resolution computed tomography in quality assurance of remote after-loading system for cervical cancer.

Intracavitary brachytherapy with a remote after-loading system (RALS) is performed as a part of radical radiation therapy in cervical cancer. The radiation source is delivered directly through an applicator placed inside the uterus or vagina. Thorough quality control is important to prevent accidents that can lead to serious irradiation error, and an applicator check is one such quality control measure. We experienced a clinical situation in which a small volume of water was observed in the lumen of a post-sterilized applicator on treatment-planning CT. Although the submersion test was negative and no air bubbles emerged from the applicator, ultra-high-resolution computed tomography (U-HRCT) showed a linear crack reaching the inside of the applicator. This abnormality was not identified on treatment-planning CT, which has lower spatial resolution than U-HRCT. In addition, no linear cracks were seen on U-HRCT images of eight other applicators considered to be free from damage. U-HRCT may have superior potential to detect applicator damage and could be useful for quality assurance of the RALS procedure.

Ultrahigh-resolution Photon-counting Detector CT Detects A Significantly Lower Coronary Plaque Burden Than Energy-integrating Detector CT

Ultrahigh-resolution Photon-counting Detector CT Detects A Significantly Lower Coronary Plaque Burden Than Energy-integrating Detector CT

Ultrahigh-resolution Photon-counting Detector CT Reclassifies Nearly Half Of Patients To A Lower CAD-RADS Category: Results From A Prospective, Intra-individual Comparison To Energy-integrating Detector CT

Ultrahigh-resolution Photon-counting Detector CT Reclassifies Nearly Half Of Patients To A Lower CAD-RADS Category: Results From A Prospective, Intra-individual Comparison To Energy-integrating Detector CT

Ultrahigh-resolution Photon-counting Detector CT Reclassifies Nearly Half Of Patients To A Lower CAD-RADS Category: Results From A Prospective, Intra-individual Comparison To Energy-integrating Detector CT

Ultrahigh-resolution Photon-counting Detector CT Reclassifies Nearly Half Of Patients To A Lower CAD-RADS Category: Results From A Prospective, Intra-individual Comparison To Energy-integrating Detector CT

Ccta By Ultra-high Resolution Ct Scanner Is Associated With Reduced Coronary Stenosis Severity

Ccta By Ultra-high Resolution Ct Scanner Is Associated With Reduced Coronary Stenosis Severity

Utility of Ultrahigh-Resolution Computed Tomography for Laryngeal Reconstructive Surgery.

Unilateral vocal fold paralysis (UVFP) presents as incomplete glottal closure and leads to breathy hoarseness. Various treatments, including laryngeal framework surgery (type 1 thyroplasty [TP1] and arytenoid adduction [AA]), have been devised to correct this condition. Ultrahigh-resolution computed tomography (U-HRCT) allows detailed three-dimensional imaging of the larynx, which aids our understanding of vocal fold motion disorders. This study assessed whether U-HRCT is beneficial for correct diagnosis and surgical planning. The participants were 26 UVFP patients who underwent laryngeal framework surgery (TP1 and/or AA). U-HRCT was used to measure the vocal fold volume (VFV) and level difference (LD). The need to combine AA with TP1 to obtain satisfactory surgical outcomes was evaluated by U-HRCT and various voice function tests. VFV was smaller in paralyzed folds than in unaffected folds. LD correlated strongly with voice parameters and showed high intra-rater and inter-rater reliability. The surgical outcome of the laryngeal framework surgery performed was judged to be excellent for improving voice function. Comparison of LD between the TP1 group and TP1 + AA group indicated that LD is an excellent parameter to determine the need to combine AA with TP1. These findings underscore the value of preoperative U-HRCT, especially LD, in surgical decision-making and afford insights for optimal phonosurgery and individualized intervention. Patients with LD >1.0 mm may benefit from thyroplasty with AA. 3 (case-control study) Laryngoscope, 134:4667-4673, 2024.

Radiation dose reduction and image quality improvement with ultra-high resolution temporal bone CT using deep learning-based reconstruction: An anatomical study

PurposeThe purpose of this study was to evaluate the achievable radiation dose reduction of an ultra-high resolution computed tomography (UHR-CT) scanner using deep learning reconstruction (DLR) while maintaining temporal bone image quality equal to or better than high-resolution CT (HR-CT). Materials and methodsUHR-CT acquisitions were performed with variable tube voltages and currents at eight different dose levels (volumic CT dose index [CTDIvol] range: 4.6–79 mGy), 10242 matrix, and 0.25 mm slice thickness and reconstructed using DLR and hybrid iterative reconstruction (HIR) algorithms. HR-CT images were acquired using a standard protocol (120 kV/220 mAs; CTDI vol, 54.2 mGy, 5122 matrix, and 0.5 mm slice thickness). Two radiologists rated the image quality of seven structures using a five point confidence scale on six cadaveric temporal bone CTs. A global image quality score was obtained for each CT protocol by summing the image quality scores of all structures. ResultsWith DLR, UHR-CT at 120 kV/220 mAs (CTDIvol, 50.9 mGy) and 140 kV/220 mAs (CTDIvol, 79 mGy) received the highest global image quality scores (4.88 ± 0.32 [standard deviation (SD)] [range: 4–5] and 4.85 ± 0.35 [range: 4–5], respectively; P = 0.31), while HR-CT at 120 kV/220 mAs and UHR-CT at 120 kV/20 mAs received the lowest (i.e., 3.14 ± 0.75 [SD] [range: 2–5] and 2.97 ± 0.86 [SD] [range: 1–5], respectively; P = 0.14). All the DLR protocols had better image quality scores than HR-CT with HIR. ConclusionUHR-CT with DLR can be performed with up to a tenfold reduction in radiation dose compared to HR-CT with HIR while maintaining or improving image quality.

Ultra-high-resolution CT vs. invasive angiography for detecting hemodynamically significant coronary artery disease: Rationale and methods of the CORE-PRECISION multicenter study

BackgroundDirect coronary arterial evaluation via computed tomography (CT) angiography is the most accurate noninvasive test for the diagnosis of coronary artery disease (CAD). However, diagnostic accuracy is limited in the setting of severe coronary calcification or stents. Ultra-high-resolution CT (UHR-CT) may overcome this limitation, but no rigorous study has tested this hypothesis. MethodsThe CORE-PRECISION is an international, multicenter, prospective diagnostic accuracy study testing the non-inferiority of UHR-CT compared to invasive coronary angiography (ICA) for identifying patients with hemodynamically significant CAD. The study will enroll 150 patients with history of CAD, defined as prior documentation of lumen obstruction, stenting, or a calcium score ≥400, who will undergo UHR-CT before clinically prompted ICA. Assessment of hemodynamically significant CAD by UHR-CT and ICA will follow clinical standards. The reference standard will be the quantitative flow ratio (QFR) with <0.8 defined as abnormal. All data will be analyzed in independent core laboratories. ResultsThe primary outcome will be the comparative diagnostic accuracy of UHR-CT vs. ICA for detecting hemodynamically significant CAD on a patient level. Secondary analyses will focus on vessel level diagnostic accuracy, quantitative stenosis analysis, automated contour detection, in-depth plaque analysis, and others. ConclusionCORE-PRECISION aims to investigate if UHR-CT is non-inferior to ICA for detecting hemodynamically significant CAD in high-risk patients, including those with severe coronary calcification or stents. We anticipate this study to provide valuable insights into the utility of UHR-CT in this challenging population and for its potential to establish a new standard for CAD assessment.

Influence of helical pitch and gantry rotation time on image quality and file size in ultrahigh-resolution photon-counting detector CT

The goal of this experimental study was to quantify the influence of helical pitch and gantry rotation time on image quality and file size in ultrahigh-resolution photon-counting CT (UHR-PCCT). Cervical and lumbar spine, pelvis, and upper legs of two fresh-frozen cadaveric specimens were subjected to nine dose-matched UHR-PCCT scan protocols employing a collimation of 120 × 0.2 mm with varying pitch (0.3/1.0/1.2) and rotation time (0.25/0.5/1.0 s). Image quality was analyzed independently by five radiologists and further substantiated by placing normed regions of interest to record mean signal attenuation and noise. Effective mAs, CT dose index (CTDIvol), size-specific dose estimate (SSDE), scan duration, and raw data file size were compared. Regardless of anatomical region, no significant difference was ascertained for CTDIvol (p ≥ 0.204) and SSDE (p ≥ 0.240) among protocols. While exam duration differed substantially (all p ≤ 0.016), the lowest scan time was recorded for high-pitch protocols (4.3 ± 1.0 s) and the highest for low-pitch protocols (43.6 ± 15.4 s). The combination of high helical pitch and short gantry rotation times produced the lowest perceived image quality (intraclass correlation coefficient 0.866; 95% confidence interval 0.807–0.910; p < 0.001) and highest noise. Raw data size increased with acquisition time (15.4 ± 5.0 to 235.0 ± 83.5 GByte; p ≤ 0.013). Rotation time and pitch factor have considerable influence on image quality in UHR-PCCT and must therefore be chosen deliberately for different musculoskeletal imaging tasks. In examinations with long acquisition times, raw data size increases considerably, consequently limiting clinical applicability for larger scan volumes.

Ultra-high-resolution CT of the temporal bone: The end of stapes prosthesis dimensional error and correlation with patient symptoms

PurposeTo describe the reliability of ultra-high-resolution computed tomography (UHR-CT) in the measurement of titanium stapes prostheses using manufacturer data as a reference. Materials and methodsThis retrospective study included patients treated by stapedectomy with titanium prostheses who underwent UHR-CT between January 2020 and October 2023. Images were acquired using an ultra-high-resolution mode (slice thickness: 0.25 mm; matrix, 1024 × 1024). Two radiologists independently evaluated the length, diameter, and intra-vestibular protrusion of the prosthesis. Post-operative air-bone gaps (ABGs) were recorded. ResultsFourteen patients were enrolled (mean age, 44.3 ± 13.8 [SD] years, 9 females), resulting in 16 temporal bone UHR-CTs. The exact length was obtained in 81.3 % (n = 13/16) and underestimated by 0.1 to 0.3 mm in the remaining 18.7 % (n = 3/16) CT scans for both readers (mean misestimation: −0.02 ± 0.06 [SD] mm, overall underestimation of 0.43 %). The exact diameter was reported in 75 % (n = 12/16) and 87.5 % (n = 14/16) of the CT scans for readers 1 and 2, respectively, and was off by 0.1 mm in all discrepancies (mean misestimation: 0.01 ± 0.04 [SD] mm, overall overestimation of 2.43 %). Intravestibular prosthesis protrusion was of 0.5 ± 0.43 [SD] mm (range: 0–1) and 0.49 ± 0.44 [SD] mm (range: 0–1.1) for readers 1 and 2, respectively, and did not correlate with ABGs (r = 0.25 and 0.22; P = 0.39 and 0.47 for readers 1 and 2, respectively). Intra and interobserver agreements were excellent. ConclusionUHR-CT provides 99.6 % and 97.6 % accuracy for prosthesis length and diameter measurements, respectively.

Associations of fractional exhaled nitric oxide with airway dimension and mucus plugs on ultra-high-resolution computed tomography in former smokers and nonsmokers with asthma

BackgroundAssociations of fractional exhaled nitric oxide (FeNO) with airway wall remodeling and mucus plugs remain to be explored in smokers and nonsmokers with asthma. Ultra-high-resolution computed tomography (U-HRCT), which allows accurate structural quantification of airways >1 mm in diameter, was used in this study to examine whether higher FeNO was associated with thicker walls of the 3rd to 6th generation airways and mucus plugging in patients with asthma. MethodsThe retrospective analyses included consecutive former smokers and nonsmokers with asthma who underwent U-HRCT in a hospital. The ratio of wall area to summed lumen and wall area was calculated as the wall area percent (WA%). Mucus plugging was visually scored. ResultsNinety-seven patients with asthma (including 59 former smokers) were classified into low (<20 ppb), middle (20–35 ppb), and high (>35 ppb) FeNO groups (n = 24, 26, and 47). In analysis including all patients and subanalysis including nonsmokers or former smokers, WA% in the 6th generation airways was consistently higher in the high FeNO group than in the low FeNO group, whereas WA% in the 3rd to 5th generation airways was not. In multivariable models, WA% in the 6th generation airways and the rate of mucus plugging were higher in the high FeNO group than in the low FeNO group after adjusting for age, sex, body mass index, smoking status, lung volume, and allergic rhinitis presence. ConclusionsHigher FeNO may reflect the inflammation and remodeling of relatively peripheral airways in asthma in both former smokers and nonsmokers.

Extremity radiographs derived from low-dose ultra-high-resolution CT: a phantom study.

To demonstrate the potential of low-dose ultra-high-resolution CT (UHRCT) images to generate high-quality radiographic images on extremity phantoms and to estimate the radiation dose required for this. A hand and knee phantom containing real human bones was imaged on an UHRCT scanner at full-dose, half-dose, and quarter-dose levels using a high-resolution extremity protocol. The raw data was reconstructed using both filtered back projection (FBP) and an iterative reconstruction algorithm (AIDR3D). Using custom designed software, each CT volume data set was converted to attenuation coefficients, and then a synthesized radiograph (synDX) was generated by forward projecting the volume data sets from a point source onto a 2D synthetic detector. The signal-to-noise ratio (SNR) was measured in the synDXs across all dose levels and the root-mean-squared error (RMSE) was computed with the FD synDXs as the reference. The proposed workflow generates high-quality synDXs at any arbitrary angle. For FBP, the SNR largely tracked with the radiation dose levels for both the knee and hand phantoms. For the knee phantom, iterative reconstruction provided a 6.1% higher SNR when compared to FBP. The RMSE was overall higher for the lowest dose levels and monotonically decreased with increasing dose. No substantial differences were observed qualitatively in the visualization of skeletal detail of the phantoms. The fine detail provided by UHRCT acquisitions of extremities facilitates the ability to generate quality radiographs,potentially eliminating the need for additional scanning on a conventional digital radiography system.

Comparative study of the sensitivity of ultra-high-resolution CT and high-resolution CT in the diagnosis of isolated fenestral otosclerosis

PurposeTo compare the diagnostic sensitivity of ultra-high-resolution computed tomography (U-HRCT) and HRCT in isolated fenestral otosclerosis (IFO).MethodsA retrospective analysis was conducted on 85 patients (85 ears) diagnosed with IFO between October 2020 and November 2022. U-HRCT (0.1 mm thickness) was performed for 20 ears, HRCT (0.67 mm thickness) for 45 ears, and both for 20 ears. The images were evaluated by general radiologists and neuroradiologists who were blinded to the diagnosis and surgical information. The diagnostic sensitivity of U-HRCT and HRCT for detecting IFO was compared between the two groups.ResultsExcellent inter-observer agreement existed between the two neuroradiologists (Cohen’s κ coefficient 0.806, 95% CI 0.692–0.920), with good agreement between the general radiologists (Cohen’s κ coefficient 0.680, 95% CI 0.417–0.943). U-HRCT had a sensitivity of 100% (40/40 ears) for neuroradiologists and 87.5% (35/40 ears) for general radiologists, significantly higher than HRCT (89.2% [58/65 ears] for neuroradiologists; 41.5% [27/65 ears] for general radiologists) (p = 0.042, p′ < 0.000). General radiologists’ sensitivity with HRCT was significantly lower compared to neuroradiologists (p < 0.000), but no significant difference was observed when general radiologists switched to U-HRCT (p = 0.152). Among the 20 ears that underwent both examinations, U-HRCT detected lesions smaller than 1 mm in 5 ears, whereas HRCT’s sensitivity for neuroradiologists was 40% (2/5 ears), significantly lower than for lesions larger than 1 mm (93.3%, 14/15 ears, p = 0.032).ConclusionU-HRCT exhibits higher sensitivity than HRCT in diagnosing IFO, suggesting its potential as a screening tool for suspected otosclerosis patients.Critical relevance statementUltra-high-resolution computed tomography has the potential to become a screening tool in patients with suspected otosclerosis and to bridge the diagnostic accuracy gap between general radiologists and neuroradiologists.Key points• U-HRCT exhibits higher sensitivity than HRCT in the diagnosis of IFO.• U-HRCT has a significant advantage in the detection of less than 1 mm IFO.• U-HRCT has the potential to be used for screening of patients with suspected otosclerosis.Graphical

Potential of ultra-high-resolution CT in detecting osseous changes of temporomandibular joint: experiences in temporomandibular disorders

BackgroundOsseous changes of the temporomandibular joint (TMJ) are related to the progression of temporomandibular disorders (TMD), and computed tomography (CT) plays a vital role in disease evaluation.ObjectiveThe aims of this study were to evaluate the image quality and diagnostic value of ultra-high-resolution CT (U-HRCT) in TMD compared to cone-beam CT (CBCT).MethodsTMD patients who underwent both CBCT and U-HRCT between November 2021 and September 2022 were retrospectively included. Image quality scores were assigned for four osseous structures (the cortical and trabecular bones of the condyle, articular eminence, and glenoid fossa) by two independent observers from Score 1 (unacceptable) to Score 5 (excellent). Diagnostic classification of TMD was categorized as follows: Class A (no evident lesion), Class B (indeterminate condition) and Class C (definitive lesion). Image quality scores and diagnostic classifications were compared between CBCT and U-HRCT. The Cohen’s Kappa test, Wilcoxon signed-rank test, Chi-square test and Fisher’s exact test were conducted for statistical analysis.ResultsThirty TMD patients (median age, 30 years; interquartile range, 26–43 years; 25 females) with 60 TMJs were enrolled. Image quality scores were higher for U-HRCT than for CBCT by both observers (all Ps < 0.001). Definitive diagnoses (Class A and C) were achieved in more cases with U-HRCT than with CBCT (93.3% vs. 65.0%, Fisher’s exact value = 7.959, P = 0.012). Among the 21 cases which were ambiguously diagnosed (Class B) by CBCT, definitive diagnosis was achieved for 17 cases (81.0%) using U-HRCT.ConclusionsU-HRCT can identify osseous changes in TMD, providing improved image quality and a more definitive diagnosis, which makes it a feasible diagnostic imaging method for TMD.

Utility of follow-up ultra-high-resolution CT angiography with model-based iterative reconstruction after flow diverter treatment for cerebral aneurysms.

Follow-up examinations after flow diverter (FD) treatment for cerebral aneurysms typically involve magnetic resonance imaging (MRI) or digital subtraction angiography (DSA). However, MRI is prone to vascular defects due to metal artifacts from FD, and DSA carries a risk of ischemic complications. In the context of computed tomography angiography (CTA), this study compares the efficacy of ultra-high-resolution CT (UHRCT) and novel reconstruction techniques, such as model-based iterative reconstruction (MBIR), against conventional methods such as filtered back projection (FBP) and hybrid iterative reconstruction (IR), to determine if they are a viable alternative to DSA in clinical settings. A phantom study was conducted with the full-width half-maximum considered as the FD thickness. This study compared three reconstruction methods: MBIR, FBP, and hybrid IR. A clinical study was also conducted with 21 patients who underwent follow-up CTA after FD treatment. The FD's visibility was assessed using a 4-point scale in FBP, hybrid IR, and MBIR compared to cone-beam CT (CBCT) with angiographic systems. In the phantom study, FBP, hybrid IR, and MBIR visualized thinner FD thicknesses and improved detail rendering in that order. MBIR proved to be significantly superior in both the phantom and clinical study. UHRCT with MBIR is highly effective for follow-up evaluations after FD treatment and may become the first-choice modality in the future.