Fig 2 - uploaded by Yoshiro Hori
Content may be subject to copyright.
Left MCA calcified aneurysm and bilateral ICA stenosis with hard plaque in a 77-year-old female patient. MIP image of DE-BR-CTA ( a ) removed the calcifications of ICA and aneurysm and revealed the same aneurysm shape as with DSA ( b ). However, the DE-BR- CTA ( a ) shows a short defect at the severe stenotic site at ICA terminal ( arrow ). CTA source images ( c ) show dense calcifications around the whole circumference of the ICA and anterior wall of the left MCA aneurysm ( arrowheads ). VR image of conventional CTA ( d ) showed the dense calcification at bilateral ICA and aneurysms, but failed to reveal details
Source publication
Dual-energy CT can be applied for bone elimination in cerebral CT angiography (CTA). The aim of this study was to compare the results of dual-energy direct bone removal CTA (DE-BR-CTA) with those of digital subtraction angiography (DSA). Twelve patients with intracranial aneurysms and/or ICA stenosis underwent a dual-source CT in dual-energy mode....
Similar publications
Objective:
In the last several decades, various factors have been studied for a better evaluation of the risk of rupture in incidentally discovered intracranial aneurysms (IAs). With advanced MRI, attempts were made to delineate the wall of IAs to identify weak areas prone to rupture. However, the field strength of the MRI investigations was insuf...
Background
For peripheral artery disease (PAD), MR angiography (MRA) is a well‐established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this.
Purpose
To evaluate the diagnostic accuracy of time‐res...
Intra-arterial digital subtraction angiography (DSA), magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) are imaging modalities used for diagnostic work-up of non-traumatic subarachnoid haemorrhage. The aim of our study was to compare the cost-effectiveness of MRA, DSA and CTA in the first year after the bleed.
A decisi...
Purpose: Rupture of an intracranial aneurysm is a life-threatening acute cerebrovascular event that typically affects working-age people. The purpose of this study was to investigate whether aneurysmal subarachnoid haemorrhage (SAH) incidence rate is higher in elderly population than in middle aged population.
Materials and methods: Aneurysmal SAH...
The most common cause of spontaneous SAH is the rupture of cerebral aneurysm. So it is very important to exclude it from circulation as soon as possible using endovascular therapy. The aim was to determine whether contrast enhancement magnetic resonance angiography (CEMRA) is preferable to computed tomography angiography (CTA) in detection of intra...
Citations
... Future technical efforts should be spent on improving the visualization of the C2 to C5 segments of the internal carotid arteries and V1 to V3 segments of the vertebral arteries. This may not only be realized by training the algorithm with more cases, but perhaps even more by sophisticating the algorithm with methods such as automatic bone removal and vessel tracking [12][13][14][15]. Nevertheless, this limitation of the current algorithm may be considered minor, because the far majority of treatable LVOs are located elsewhere, i.e., typically M1 and M2 segments of the middle cerebral artery, at the T-junction where the internal carotid artery bifurcates into the middle cerebral artery, at the C1 segment of the internal carotid artery (although this may proceed more distally), and in the basilar artery, which were all well visualized at focused view CTA. ...
... Since the advent of spiral and multi-detector row CT more than 25 years ago, CTA has gradually evolved into an accepted minimally invasive and less costly alternative to catheter angiography [17]. Previous studies have demonstrated the feasibility of removing bone from CTA data to improve the assessment of arteries close to bone [12,13]. Other techniques, including deep learning models, have been reported to selectively visualize the intracranial arteries [6,[18][19][20]. ...
Objectives
This study investigated the technical feasibility of focused view CTA for the selective visualization of stroke related arteries.
Methods
A total of 141 CTA examinations for acute ischemic stroke evaluation were divided into a set of 100 cases to train a deep learning algorithm (dubbed “focused view CTA”) that selectively extracts brain (including intracranial arteries) and extracranial arteries, and a test set of 41 cases. The visibility of anatomic structures at focused view and unmodified CTA was assessed using the following scoring system: 5 = completely visible, diagnostically sufficient; 4 = nearly completely visible, diagnostically sufficient; 3 = incompletely visible, barely diagnostically sufficient; 2 = hardly visible, diagnostically insufficient; 1 = not visible, diagnostically insufficient.
Results
At focused view CTA, median scores for the aortic arch, subclavian arteries, common carotid arteries, C1, C6, and C7 segments of the internal carotid arteries, V4 segment of the vertebral arteries, basilar artery, cerebellum including cerebellar arteries, cerebrum including cerebral arteries, and dural venous sinuses, were all 4. Median scores for the C2 to C5 segments of the internal carotid arteries, and V1 to V3 segments of the vertebral arteries ranged between 3 and 2. At unmodified CTA, median score for all above-mentioned anatomic structures was 5, which was significantly higher ( p < 0.0001) than that at focused view CTA.
Conclusion
Focused view CTA shows promise for the selective visualization of stroke-related arteries. Further improvements should focus on more accurately visualizing the smaller and tortuous internal carotid and vertebral artery segments close to bone.
Clinical relevance
Focused view CTA may speed up image interpretation time for LVO detection and may potentially be used as a tool to study the clinical relevance of incidental findings in future prospective long-term follow-up studies.
Key Points
• A deep learning–based algorithm (“focused view CTA”) was developed to selectively visualize relevant structures for acute ischemic stroke evaluation at CTA.
• The elimination of unrequested anatomic background information was complete in all cases.
• Focused view CTA may be used to study the clinical relevance of incidental findings.
... For CTA, information and images about the direction of the aneurysm are also adequate surgical experiences to prove this. 3D and dual-energy devices let physicians remove surrounding tissues like bones to preserve specific images 14,15,18 . ...
Objective:
Subarachnoid hemorrhage (SAH) due to an intracranial aneurysm is a life-threatening surgical emergency. After the diagnosis of SAH, physicians should find the reason for the bleeding. CT- Angiography (CTA) and Digital Subtraction Angiography (DSA) are techniques used to visualize the aneurysm. However, which one will surgeons prefer? In this study, we have compared these two radiological examinations.
Patients and methods:
This study includes 58 patients diagnosed with SAH and intracranial aneurysm diagnosis based on CTA (n=30) and DSA (n=28). We evaluated the patients according to demographic properties, CTA and DAS findings, aneurysm location, Fisher score, postoperative complications, and Glasgow outcome score.
Results:
The most common location of aneurysms was the M1 level (48.3%). Patients in the DSA group had significantly more extended hospital stays (p= 0.021). There was no statistically significant difference between the two groups in complications.
Conclusions:
Enhanced CT Technologies provide higher fidelity images and shorten hospital stays. With CTA, surgeons may gain time for an emergency surgical procedure. Despite the fact that DSA remains a significant factor in aneurysm diagnosis, DSA is an invasive procedure and needs more time to diagnose.
... A clinically well-established method that enables material decomposition in general is dual-energy CT (DE-CT) 1 . There are several options for DE-CT, such as dual-source CT (DS-CT), rapid kVp-switching, and dual-layer CT (DL-CT), all of which are well-known options in the clinical setting [2][3][4][5][6][7][8][9] . For this study, a DL-CT scanner system was used, which differs from the other DE-CT options mainly in the type of detector arrangement. ...
... This optimization refers to the Eqs. (3), (4) and (5). Here i corresponds to the abbreviations of RBC, WBC, fibrin/platelets, formalin and iomeprol. ...
The separation of mixtures of substances into their individual components plays an important role in many areas of science. In medical imaging, one method is the established analysis using dual-energy computed tomography. However, when analyzing mixtures consisting of more than three individual basis materials, a physical limit is reached that no longer allows this standard analysis. In addition, the X-ray attenuation coefficients of chemically complicated basis materials may not be known and also cannot be determined by other or previous analyses. To address these issues, we developed a novel theoretical approach and algorithm and tested it on samples prepared in the laboratory as well as on ex-vivo medical samples. This method allowed both five-material decomposition and determination or optimization of the X-ray attenuation coefficients of the sample base materials via optimizations of objective functions. After implementation, this new multimodal method was successfully tested on self-mixed samples consisting of the aqueous base solutions iomeprol, eosin Y disodiumsalt, sodium chloride, and pure water. As a first proof of concept of this technique for detailed material decomposition in medicine we analyzed exact percentage composition of ex vivo clots from patients with acute ischemic stroke, using histological analysis as a reference standard.
... DECT uses two datasets with different energy spectra in contrast to single energy scanning methods that use only one spectrum. Therefore, DECT has several advantages such as visualization and quantification of iodine, automated bone subtraction in CT angiography, detection of perfusion defects caused by pulmonary embolism, and detection of bone marrow edema (BME) [1][2][3][4][5]. BME is not a disease but a general condition arising due to various factors including trauma and hemorrhage in the bone marrow following a bone fracture and inflammation associated with conditions such as osteomyelitis, osteonecrosis, arthritis of the joints, and bone marrow infiltration by tumor cells [6][7][8]. ...
... It is also one of the first signs of inexplicable pain or teeth mobility [28]. Recently, DECT has not become available in clinical practice to detect BME caused by various diseases [1][2][3][4][5]. It is being used to visualize subtle bone involvement in oncology, osteomyelitis, and osteonecrosis of the head and neck region [8]. ...
Purpose
In this study, we prospectively investigated the relationship between bone marrow edema (BME) and odontogenic cysts and explored the possibility of using dual-energy computed tomography (DECT) as an auxiliary tool for the diagnosis of odontogenic cysts.
Methods
This cross-sectional study included 73 patients who underwent the DECT scan and surgery for odontogenic cysts or odontogenic tumors. The virtual noncalcium (VNCa) computed tomography (CT) values and CT values were measured at several sites. The predictor variable was diagnosis, and the other variables included age, sex, and sites. The primary outcome was VNCa CT value. Variables were tested using the chi-square test or the Kruskal–Wallis test. The VNCa CT and CT values were tested using the Scheffe test for multiple comparisons. All variables were analyzed as independent variables affecting the VNCa CT values around the lesion in the multiple regression analysis.
Result
There were 35 men and 38 women. The mean patient age was 50.0 ± 19.5 years (range: 8–86). The VNCa CT values (− 6.2 ± 34.3) around the lesion in patients with RCs were significantly higher than those in patients with dentigerous cysts (− 44.4 ± 28.6) and odontogenic keratocysts (− 67.3 ± 19.5). In multiple regression analysis, the VNCa CT values around the lesion showed a significant positive correlation with histological results (regression coefficient: − 0.605, P < 0.001).
Conclusion
The presence of BME is associated with radicular cysts, and DECT can be used as an auxiliary tool for radicular cyst diagnosis.
... One observer missed two isolated distal intracranial carotid artery occlusions (near the skull base), whereas the other observer missed an occlusion in the M1-segment due to a calcified embolus. The use of dual-energy CT angiography technology with bone removal may increase the conspicuity of these LVOs [19,20]. Another promising technique is CT perfusion-based wavelet-transformed angiography, which uses temporal wavelet transforms of intracranial CT perfusion datasets, and provides higher vascular contrast and intrinsic removal of non-enhancing structures such as bone [21]. ...
PurposeTo evaluate the reliability and accuracy of thick maximum intensity projection (MIP) CTA images to detect large-vessel occlusion (LVO) in the anterior circulation in patients with acute stroke.MethodsA total of 140 acute stroke patients (41 with and 99 without LVO) were evaluated by two neuroradiologists for LVO using axial 3-mm and 2-mm MIPs.ResultsInterobserver agreement was substantial using 3-mm MIPs (ĸ = 0.67) and almost perfect using 2-mm MIPs (ĸ = 0.82). Using 3-mm MIPs, sensitivities were 80.5% and 68.3%, with specificities of 98.0% and 96.0%. Using 2-mm MIPs, sensitivities were 82.9% and 73.2%, with specificities of 98.0% and 99.0%. Sensitivity and specificity of 3 mm and 2 mm MIPs were not statistically significantly different (P ≥ 0.375). The majority of LVOs in the distal intracranial carotid artery, and/or M1-segment were correctly identified: 96.0% (observer 1, 3-mm MIPs), 88.0% (observer 2, 3-mm MIPs), 96.0% (observer 1, 2-mm MIPs), and 96.0% (observer 2, 2 mm MIPs). Using 3-mm MIP images, observers 1 and 2 missed 7/15 (46.7%) and 9/15 (60.0%) of isolated M2-segment occlusions, respectively. Using 2-mm MIP images, observers 1 and 2 missed 5/15 (33.3%) and 6/15 (40.0%) of isolated M2-segment occlusions, respectively.Conclusion
Thick (2–3 mm) axial MIPs are not useful to detect proximal LVO in the anterior circulation.
... 86 This technology has been used in human medicine most prominently in angiography, abdominal imaging, characterisation of urinary stones and for gout arthropathy, and has also been reported to identify bone marrow lesions, visualise tendons and ligaments, and minimise beamhardening artifacts from bone prostheses. [86][87][88][89][90][91][92] Although the underlying principles are the same, it is important to note that DECT can be accomplished by using single-or dual-source CT scanners. Singlesource CT scanners used for DECT rapidly (ie, 0.5-s intervals) switch between high-and low-energy during a single rotation of the gantry. ...
Access to volumetric imaging modalities, such as magnetic resonance imaging (MRI) and computed tomography (CT), has increased over the past decade and has revolutionised the way clinicians evaluate equine anatomy. More recent advancements have resulted in the development of multiple commercially available cone‐beam CT (CBCT) scanners for equine use. CBCT scanners modify the traditional fan‐shaped beam of ionising radiation into a three‐dimensional pyramidal‐ or cone‐shaped beam of radiation. This modification enables the scanner to acquire sufficient data to create diagnostic images of a region of interest after a single rotation of the gantry. The rapid acquisition of data and divergent X‐ray beam causes some artifacts to be more prominent on CBCT images—as well as the unique cone‐beam artifact—resulting in decreased contrast resolution. While the use of CT for evaluation of the equine musculoskeletal anatomy is not new, there is a paucity of literature and scientific studies on the capabilities of CBCT for equine imaging. CBCT units do not require a specialised table for imaging and in some cases are portable for imaging in the standing or anaesthetised patient. This review article summarises the basic physics of CT technology, including how CBCT imaging differs, and provides objective information about the strengths and limitations of this modality. Finally, potential future applications and techniques for imaging with CT which will need to be explored in order to fully consider the capabilities of CT imaging in the horse are discussed.
... Materials with same HU value on one energy level can represent differently on the other level due to their different energy dependence of photoelectric, Compton and Rayleigh interactions. Based on the DECT images, derivative images can be generated for advanced clinical use such as bone maps for removal in angiography (Ruzsics et al 2008, Tran et al 2009, Watanabe et al 2009, Kau et al 2011 and relative stopping power maps for proton radiation therapy treatment planning (Yang et al 2010, Zhu and Penfold 2016, Wohlfahrt et al 2018. Latest studies have shown that DECT and its derivatives may outperform conventional SECT for manual contouring because of the provided superior contrast-noise-ratio (Pomerantz et al 2013, Wichmann et al 2014, Frellesen et al 2015, Lam et al 2015, Di Maso et al 2018. ...
Organ delineation is crucial to diagnosis and therapy, while is also labor-intensive and observer-dependent. Dual energy CT (DECT) provides additional image contrast than conventional single energy CT (SECT), which may facilitate automatic organ segmentation. This work aims to develop an automatic multi-organ segmentation approach using deep learning for head-and-neck region on DECT. We proposed a Mask scoring R-CNN where comprehensive features are firstly learnt from two independent pyramid networks and are then combined via deep attention strategy to highlight the informative ones extracted from DECT. To perform multi-organ segmentation and avoid misclassification, a mask scoring subnetwork was integrated into the Mask R-CNN framework to build the correlation between the class of potential detected organ's region-of-interest (ROI) and the shape of that organ's segmentation within that ROI. We evaluated our model on DECT images from 127 head-and-neck cancer patients (66 training, 61 testing) with manual contours of 19 organs as ground truth. For large- and mid-sized organs such as brain and parotid, the proposed method successfully achieved average Dice similarity coefficient (DSC) larger than 0.8. For small-sized organs with very low contrast such as chiasm, cochlea, lens and optic nerves, the DSCs ranged between around 0.5 and 0.8. With the propose method, using DECT images outperforms using SECT in almost all 19 organs with statistical significance in DSC (p<0.05). Meanwhile, by using the DECT, the proposed method is also significantly superior to a recently developed FCN-based method in most of organs in terms of DSC and the 95th percentile Hausdorff distance. Quantitative results demonstrated the feasibility of the proposed method, the superiority of using DECT to SECT, and the advantage of the proposed R-CNN over FCN on the head-and-neck patient study. The proposed method has the potential to facilitate the current head-and-neck cancer radiation therapy workflow in treatment planning.
... Dual-energy CT has also been shown to be superior to standard CTA in detecting aneurysm adjacent to skull base. [19] Karcaaltincaba also discusses other uses of dual-energy CT in the neuroradiology setting. [8] is includes removal of bone and calcium from CTA to further assess cerebral vasculature, allowing increased accuracy in identifying cerebral aneurysms. ...
Background
Along with surgical clipping, endovascular management is one of the mainstay treatment options for cerebral aneurysms. However, immediate post procedural imaging is often hard to interpret due to the presence of contrast material. Dual-energy computed tomography (CT) allows differentiation between contrast extravasation and intracranial hemorrhage and this case illustrates the importance of this following endovascular treatment of an unruptured cerebral aneurysm.
Case Description
A patient presented with acute ophthalmoplegia secondary to mass effect from an intracavernous ICA fusiform aneurysm. The patient underwent an endovascular flow diverting stent to treat this aneurysm. Post procedure, the patient had a reduced level of consciousness and underwent a conventional CT showing diffuse subarachnoid hyperdensity of the left hemisphere. Dual-energy CT allowed accurate differentiation and illustrated diffuse contrast material extravasation, allowing patient to continue on dual antiplatelets and therapeutic anticoagulation to reduce the risk of ischemic injury post endovascular stent.
Conclusion
Use of dual-energy CT in the setting of endovascular management of intracranial aneurysms allows accurate diagnosis of any postoperative complications. Specifically, differentiating between subarachnoid hemorrhage and contrast extravasation is vital in these patients due to the significant consequences to their ongoing management in regard to continuation or cessation of antiplatelets or anticoagulation. With increasing access to this technology, its use should become standard practice in the post-operative investigation of these patients undergoing endovascular treatment.
... While this technique yields very good images, radiation delivered is more and the technique is prone to motion degradation [40]. Dual-energy CT angiography has also been shown to perform well for skull base aneurysm detection by Watanabe [41]. To minimize false negative rates, Westerlan et al. suggest that all negative CTA should have a second-look interpretation by an experienced neuroradiologist [30]. ...
The purpose of this review is to understand the role of imaging in the diagnosis and management of non-traumatic subarachnoid hemorrhage (SAH). SAH is a life-threatening emergency and a relatively common entity, the most common etiology being ruptured aneurysms. Multiple conundrums exist in literature at various steps of its imaging workup: diagnosis, management, and follow-up. We target our review to highlight the most effective practice and suggest efficient workup plans based on literature search, and describe in detail the clinical diagnostic and prognostic scales, role of CT scan, lumbar puncture, and MR, including angiography in the diagnosis and workup of SAH and its complications, and try to simplify the conundrums. Practical knowledge of imaging workup of SAH can help guide correct management of these patients, so as to reduce morbidity and mortality without resource overutilization.
... Dual-energy CT (DECT), as an advanced CT imaging scheme, is being introduced into multiple usage in radiology as well as radiation therapy. It has been an important imaging modality with special clinical applications in radiology where conventional single energy CT (SECT) falls short, including bone removal in angiography [20,34,41,48], assessment of myocardial blood supply [35,40,52], renal calculi characterization [14,32], and diagnosis of gout [12,28]. In these applications, DECT provides material specific information which is extracted by processing the projection datasets of two different energy spectra acquired by DECT [5,13,25,50,51]. ...
Purpose: Dual-energy CT (DECT) has been shown to derive stopping power ratio (SPR) map with higher accuracy than conventional single energy CT (SECT) by obtaining the energy dependence of photon interactions. However, DECT is not as widely implemented as SECT in proton radiation therapy simulation. This work presents a learning-based method to synthetize DECT images from SECT for proton radiation therapy. Methods: The proposed method uses a residual attention generative adversarial network. Residual blocks with attention gates were used to force the model focus on the difference between DECT maps and SECT images. To evaluate the accuracy of the method, we retrospectively investigated 20 head-and-neck cancer patients with both DECT and SECT scans available. The high and low energy CT images acquired from DECT acted as learning targets in the training process for SECT datasets and were evaluated against results from the proposed method using a leave-one-out cross-validation strategy. To evaluate our method in the context of a practical application, we generated SPR maps from sDECT using physics-based dual-energy stoichiometric method and compared the maps to those generated from DECT. Results: The synthesized DECT images showed an average mean absolute error around 30 Hounsfield Unit (HU) across the whole-body volume. The corresponding SPR maps generated from synthetic DECT showed an average normalized mean square error of about 1% with reduced noise level and artifacts than those from original DECT. Conclusions: The accuracy of the synthesized DECT image by our machine-learning-based method was evaluated on head and neck patient, and potential feasibility for proton treatment planning and dose calculation was shown by generating SPR map using the synthesized DECT.
