Subtraction CT Research Articles

Multiple predictors of in-stent restenosis after stent implantation in symptomatic intracranial atherosclerotic stenosis.

This study aimed to identify predictors of intracranial in-stent restenosis (ISR) after stent placement in symptomatic intracranial atherosclerotic stenosis (ICAS). The authors retrospectively collected data from consecutive patients who suffered from symptomatic ICAS and underwent successful stent placement in Beijing Tiantan hospital. Eligible patients were classified into "ISR," "indeterminate ISR," or "no-ISR" groups by follow-up digital subtraction angiography or CT angiography. A multivariate logistic regression model was used to explore the predictors of intracranial ISR after adjustments for age and sex. In addition, ISR and no-ISR patients were divided into two groups based on the strongest predictor, and the incidence of ISR, recurrent stroke, and symptomatic ISR was compared between the two groups. A total of 511 eligible patients were included in the study: 80 ISR, 232 indeterminate ISR, and 199 no-ISR patients. Elevated high-sensitivity C-reactive protein (hs-CRP; odds ratio [OR] 4.747, 95% confidence interval [CI] 2.253-10.01, p < 0.001), Mori type B and C (Mori type B vs Mori type A, OR 3.119, 95% CI 1.093-8.896, p = 0.033; Mori type C vs Mori type A, OR 4.780, 95% CI 1.244-18.37, p = 0.023), coronary artery disease (CAD; OR 2.721, 95% CI 1.192-6.212, p = 0.017), neutrophil/lymphocyte ratio (NLR; OR 1.474 95% CI 1.064-2.042, p = 0.020), residual stenosis (OR 1.050, 95% CI 1.022-1.080, p = 0.001) and concurrent intracranial tandem stenosis (OR 2.276, 95% CI 1.039-4.986, p = 0.040) synergistically contributed to the occurrence of intracranial ISR. Elevated hs-CRP (hs-CRP ≥ 3 mg/L) was the strongest predictor for ISR, and the incidence of ISR in the elevated hs-CRP group and normal hs-CRP group (hs-CRP < 3 mg/L) was 57.14% versus 21.52%, respectively, with recurrent stroke 44.64% versus 16.59%, and symptomatic ISR 41.07% versus 8.52%. Elevated hs-CRP level, NLR, residual stenosis, Mori type B and C, CAD, and concurrent intracranial tandem stenosis are the main predictors of intracranial ISR, and elevated hs-CRP is crucially associated with recurrent stroke in patients with symptomatic ICAS after intracranial stent implantation.

Perfusion imaging techniques in lower extremity peripheral arterial disease.

Lower limb peripheral arterial disease (PAD) characterizes the impairment of blood flow to extremities caused by arterial stenoses or occlusions. Evaluation of PAD is based on clinical examination, calculation of ankle-brachial index and imaging studies such as ultrasound, CT, MRI and digital subtraction angiography. These modalities provide significant information about location, extension and severity of macrovasular lesions in lower extremity arterial system. However, they can be also used to evaluate limb perfusion, using appropriate techniques and protocols. This information may be valuable for assessment of the severity of ischemia and detection of hypoperfused areas. Moreover, they can be used for planning of revascularization strategy in patients with severe PAD and evaluation of therapeutic outcome. These techniques may also determine prognosis and amputation risk in patients with PAD. This review gives a basic overview of the perfusion techniques for lower limbs provided by imaging modalities such as ultrasound, CT, MRI, digital subtraction angiography and scintigraphy and their clinical applications for evaluation of PAD and revascularization outcome.

Contrast-enhanced CT techniques and MRI perform equally well in arthritis imaging of the hand: a prospective diagnostic accuracy study

ObjectivesTo investigate the performance of dual-energy CT (DECT)-generated iodine maps (iMap) and CT subtraction (CT-S) in the detection of synovitis, tenosynovitis, and peritendonitis/paratenonitis compared to magnetic resonance imaging (MRI) using musculoskeletal ultrasound (MSUS) as standard of reference.MethodsThis IRB-approved prospective study consecutively investigated patients with undifferentiated arthritis. All patients underwent MSUS, MRI and contrast-enhanced DECT of the hand; from the latter conventional CT-S, image-based iMap (iMap-I) and raw data-based iMap (iMap-RD) were reconstructed. CT and MRI datasets were scored for synovitis and tenosynovitis/paratenonitis applying the modified Rheumatoid Arthritis MRI Score (RAMRIS). Sensitivity, specificity, and diagnostic accuracy were calculated. Non-inferiority was tested using the one-tailed McNemar test. Correlation of sum scores was assessed using Pearson’s test. Interreader reliability was assessed using Cohen’s kappa.ResultsOverall, 33 patients were included. MSUS was positive for synovitis and tenosynovitis/paratenonitis in 28 patients with a sum score of 6.91. Excellent correlation with MSUS was shown for CT-S (sum score 6.38; r = 0.91), iMap-RD (sum score 9.74; r = 0.82), MRI (sum score 12.70; r = 0.85), and iMap-I (sum score 6.94; r = 0.50). CT-S had the highest diagnostic accuracy of 83%, followed by iMap-I (78%), MRI (75%), and iMap-RD (74%). All modalities showed non-inferiority. Reader agreement was good for CT-S and MRI (κ = 0.62; 0.64) and fair for iMap-RD and iMap-I (κ = 0.31; 0.37).ConclusionCT-S and iMap allow highly standardized arthritis imaging and are suitable for clinical practice. MSUS still has the highest availability for arthritis imaging and served as gold standard for this study.Key Points• CT subtraction, iodine map with dual-energy CT, and MRI showed non-inferiority to musculoskeletal ultrasound.• MRI was the most sensitive but least specific imaging technique compared with CT subtraction and dual-energy CT.• CT subtraction showed the best correlation with musculoskeletal ultrasound.

Comparative evaluation of temporal subtraction computed tomography and non-echoplanar diffusion-weighted imaging for the mastoid extension of middle ear cholesteatoma

ObjectivePreoperative imaging assessment influences the decision to perform mastoidectomy for the mastoid extension of middle ear cholesteatoma. This study compared the performance of temporal subtraction CT (TSCT) and non-echoplanar diffusion-weighted imaging (non-EP DWI) in evaluating such mastoid extensions. MethodsWe retrospectively evaluated 239 consecutive patients with surgically proven middle ear cholesteatoma between April 2016 and April 2021. The diagnostic performance of TSCT, wherein the presence of black color indicated progressive bone erosion, and non-EP DWI, wherein high signal intensity in the mastoid region suggested mastoid extension, was compared using Fisher's exact test. ResultsIn 34 patients with evaluable TSCT images, black color was significantly more common in patients with mastoid extension than in those without; the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of TSCT were 1.00, 0.95, 0.94, 1.00, and 0.97, respectively. In 90 patients with evaluable non-EP DWI, high signal intensity was significantly more common in patients with mastoid extension than in those without; the sensitivity, specificity, PPV, NPV, and accuracy of non-EP DWI were 0.88, 0.85, 0.91, 0.81, and 0.87, respectively. In 16 patients with both evaluable TSCT and non-EP DWI, the diagnostic performance of the TSCT was slightly superior to that of the non-EP DWI for predicting mastoid extension, although the difference was not significant. ConclusionsTSCT images generated using consecutively acquired preoperative high-resolution CT images are useful for predicting mastoid extension of middle ear cholesteatoma, and the diagnostic performance of TSCT is non-inferior to that of non-EP DWI.

471 Prospective Comparison of CT and Digital Subtraction Angiography to Diagnose Penetrating Cerebrovascular Injuries: Preliminary Data

INTRODUCTION: Digital subtraction angiography (DSA) is the gold standard for detecting penetrating cerebrovascular injuries, but CT angiography (CTA) is often used. Few studies compare CTA and DSA for this indication and are retrospective, which indicate sensitivity of CTA is about 70%. METHODS: Prospective observational cohort study of all patients with penetrating head injuries at Harborview Medical Center, excluding patients with unsalvageable injuries. CTA of the head was performed immediately after presentation, followed by 6 vessel DSA within 48 hours. Sensitivity and specificity of CTA compared to DSA were then calculated. RESULTS: Enrollment is ongoing. 14 patients have undergone CTA and DSA of whom 7 have cerebrovascular injury. Of these CTA missed pathology seen on DSA in 4 cases, yielding sensitivity of 43%, all cases missing dural-arteriovenous or carotid-cavernous fistulae. In one case a small pseudoaneurysm was called on CTA that was not seen on DSA, yielding specificity of 86%. CONCLUSION: Early findings suggest that CTA is at least as insensitive for penetrating cerebrovascular injury as suggested by retrospective studies. This insensitvity is particularly relevant in cases of traumatic fistulae. More data are needed, and enrollment of subjects is ongoing at our center and at collaborating institutions.

Diagnostic Improvements of Deep Learning-Based Image Reconstruction for Assessing Calcification-Related Obstructive Coronary Artery Disease.

Objectives: The objective of this study was to explore the diagnostic value of deep learning-based image reconstruction (DLR) and hybrid iterative reconstruction (HIR) for calcification-related obstructive coronary artery disease (CAD) evaluation by using coronary CT angiography (CCTA) images and subtraction CCTA images.Methods: Forty-two consecutive patients with known or suspected coronary artery disease who underwent coronary CTA on a 320-row CT scanner and subsequent invasive coronary angiography (ICA), which was used as the reference standard, were enrolled. The DLR and HIR images were reconstructed as CTADLR and CTAHIR, and, based on which, the corresponding subtraction CCTA images were established as CTAsDLR and CTAsHIR, respectively. Qualitative images quality comparison was performed by using a Likert 4 stage score, and quantitative images quality parameters, including image noise, signal-to-noise ratio, and contrast-to-noise ratio were calculated. Diagnostic performance on the lesion level was assessed and compared among the four CCTA approaches (CTADLR, CTAHIR, CTAsDLR, and CTAsHIR).Results: There were 166 lesions of 86 vessels in 42 patients (32 men and 10 women; 62.9 ± 9.3 years) finally enrolled for analysis. The qualitative and quantitative image qualities of CTAsDLR and CTADLR were superior to those of CTAsHIR and CTAHIR, respectively. The diagnostic accuracies of CTAsDLR, CTADLR, CTAsHIR, and CTAHIR to identify calcification-related obstructive diameter stenosis were 83.73%, 69.28%, 75.30%, and 65.66%, respectively. The false-positive rates of CTAsDLR, CTADLR, CTAsHIR, and CTAHIR for luminal diameter stenosis ≥50% were 15%, 31%, 24%, and 34%, respectively. The sensitivity and the specificity to identify ≥50% luminal diameter stenosis was 90.91% and 83.23% for CTAsDLR.Conclusion: Our study showed that deep learning–based image reconstruction could improve the image quality of CCTA images and diagnostic performance for calcification-related obstructive CAD, especially when combined with subtraction technique.

Improved assessment of middle ear recurrent/residual cholesteatomas using temporal subtraction CT

PurposeThe purpose of this study was to investigate the usefulness of temporal subtraction CT (TSCT) of temporal bone CT for the detection of postoperative recurrent/residual cholesteatoma of the middle ear.MethodsThirty-two consecutive patients with surgically proven postoperative recurrent/residual cholesteatoma and 14 consecutive patients without recurrent/residual lesion matched the selection criteria and were retrospectively evaluated. TSCT imaging was generated with the use of serial postoperative CT. Two experienced radiologists and two residents evaluated the presence of bone erosive change by comparison serial CT studies, and CT and TSCT. The detection rate of bone erosive change, sensitivity and specificity of the recurrence/residual lesions, and reading time for each reader were evaluated.ResultsTSCT + CT significantly improved the detection of bone erosive changes compared to CT-only evaluation (17.4–41.3% vs. 37.0–58.7%, p = 0.008–0.046). The mean sensitivity and specificity of TSCT + CT for experienced radiologists were 0.77 and 1.00, and 0.52 and 0.97 without TSCT. The mean sensitivity and specificity of TSCT + CT for residents were 0.64 and 1.00, and 0.41 and 1.00 without TSCT. Sensitivity showed an increase in all readers. The use of TSCT significantly reduced the reading time per case in all readers (p < 0.001).ConclusionTSCT improves the depiction of newly occurring progressive bone erosive changes, and detection sensitivity and reading time in postoperative recurrence/residual cholesteatoma of middle ear.

Temporal subtraction CT with nonrigid image registration improves detection of bone metastases by radiologists: results of a large-scale observer study

To determine whether temporal subtraction (TS) CT obtained with non-rigid image registration improves detection of various bone metastases during serial clinical follow-up examinations by numerous radiologists. Six board-certified radiologists retrospectively scrutinized CT images for patients with history of malignancy sequentially. These radiologists selected 50 positive and 50 negative subjects with and without bone metastases, respectively. Furthermore, for each subject, they selected a pair of previous and current CT images satisfying predefined criteria by consensus. Previous images were non-rigidly transformed to match current images and subtracted from current images to automatically generate TS images. Subsequently, 18 radiologists independently interpreted the 100 CT image pairs to identify bone metastases, both without and with TS images, with each interpretation separated from the other by an interval of at least 30 days. Jackknife free-response receiver operating characteristics (JAFROC) analysis was conducted to assess observer performance. Compared with interpretation without TS images, interpretation with TS images was associated with a significantly higher mean figure of merit (0.710 vs. 0.658; JAFROC analysis, P = 0.0027). Mean sensitivity at lesion-based was significantly higher for interpretation with TS compared with that without TS (46.1% vs. 33.9%; P = 0.003). Mean false positive count per subject was also significantly higher for interpretation with TS than for that without TS (0.28 vs. 0.15; P < 0.001). At the subject-based, mean sensitivity was significantly higher for interpretation with TS images than that without TS images (73.2% vs. 65.4%; P = 0.003). There was no significant difference in mean specificity (0.93 vs. 0.95; P = 0.083). TS significantly improved overall performance in the detection of various bone metastases.

Anatomic Variations of the Hepatic Artery in 5625 Patients.

To analyze the origin and anatomic course of the hepatic arteries by using digital subtraction angiography (DSA) and multidetector CT in a large study sample. This retrospective study included 5625 patients who underwent liver CT and chemoembolization between January 2005 and December 2018 (mean age, 60 years ± 11 [range, 11-99 years]; 4464 males). The CT and DSA images were reviewed to evaluate the visceral arterial anatomy for variations in the celiac axis and hepatic arteries. Aberrant right hepatic arteries (aRHAs) and aberrant left hepatic arteries (aLHAs) were defined on the basis of their origin and anatomic course. Statistical analyses were performed to evaluate the association between aRHAs and aLHAs and the association between variations in the hepatic artery and celiac axis. Right hepatic arteries were categorized as being aRHAs (if originating from the proximal to middle common hepatic artery, gastroduodenal artery, superior mesenteric artery [SMA], celiac axis, aorta, splenic artery, or left gastric artery [LGA]) or as being aLHAs (if arising from the LGA, celiac axis, aorta, or SMA). The prevalence of aRHAs (15.63%; 879 of 5625) and the prevalence aLHAs (16.32%; 918 of 5625) were similar. Patients with an aRHA were more likely to have an aLHA than those without an aRHA (29.01% vs 13.97%; P < .001), and patients with an aLHA were more likely to have an aRHA than those without an aLHA (27.78% vs 13.26%; P < .001). There was no association between the hepatic arterial variations and celiac axis variations. A hypothetical anatomic model summarizing the observed variations was created. A comprehensive list of hepatic arterial variations and a three-dimensional hypothetical model for the observed variations were described.Keywords: CT, Angiography, Liver, Anatomy, Arteries© RSNA, 2021 Supplemental material is available for this article. See also commentary by Sutphin and Kalva in this issue.

Ultrasonic characteristics of carotid webs

This study aimed to retrospectively analyze the ultrasonographic images of 46 cases of carotid web (CW) and summarize their manifestations to reduce the rate of misdiagnosis. For the analysis of ultrasonic manifestations, 46 patients with a confirmed diagnosis of CW by digital subtraction angiography (DSA) and CT angiography (CTA) in our hospital from January 2015 to October 2020 were collected. The location and the morphology of CW, the presence of a plaque at the base and thrombus at the surrounding of the CW, and whether they resulted in arteriostenosis were discussed. The average age of 46 patients was 43.23 ± 4.89years old and there were 18 males and 28 females. Fifteen patients were admitted with cerebral infarction. The CW was located at the initial segment of the internal carotid artery in 22 cases, the bifurcation of the carotid artery in 20 cases, and the common carotid artery in 4 cases. CW in 5 patients was longer than half of the artery diameter, two patients with "cliff-like" arteriostenosis, 29 patients with plaques, and 16 patients with thrombi. The CW grew in the direction of the blood flow without obvious fluttering. The CW has a higher display rate on the ultrasound longitudinal section than the transverse section. We identified some typical ultrasound characteristics of CW. Recognizing them will improve diagnostic accuracy of CW by ultrasonography.

Quantitative dual-energy CT for evaluating hepatocellular carcinoma after transarterial chemoembolization

We aimed to investigate the role of the quantitative parameters of dual-energy computed tomography (DECT) in evaluating patients with hepatocellular carcinoma (HCC) treated by transarterial chemoembolization (TACE). We retrospectively identified 80 HCC patients (mean age, 56 years; 61 men) treated by TACE who received contrast-enhanced DECT and were retreated by TACE within 7 days between November 2018 and December 2019. Taking digital subtraction angiography (DSA) and CT images as reference standard, two readers measured and calculated the values of normalized iodine concentration at arterial phase (NICAP), normalized iodine concentration at portal venous phase (NICPP), iodine concentration difference (ICD), arterial iodine fraction (AIF) and slope of the spectral Hounsfield unit curve (λHu) by placing matched regions of interests (ROIs) within the tumor active area (TAA), adjacent normal hepatic parenchyma (ANHP) and tumor necrotic area (TNA). Differences between the parameters were analyzed by the Kruskal–Wallis H test. Receiver operating characteristic analysis of the parameters performance in differentiating the three tissues types was performed. AIF exhibited a good performance in distinguishing TAA (0.93 ± 0.31) and ANHP (0.18 ± 0.14), the areas under the receiver operating characteristic curve (AUC) was 0.989, while the λHu exhibited an excellent performance in distinguishing TAA (3.32 ± 1.24) and TNA (0.29 ± 0.27), with an AUC of 1.000. In conclusion, quantitative DECT can be effectively used to evaluate the tumor viability in HCC patients treated by TACE.

Performance of an artificial intelligence tool with real-time clinical workflow integration - Detection of intracranial hemorrhage and pulmonary embolism.

Performance of an artificial intelligence tool with real-time clinical workflow integration - Detection of intracranial hemorrhage and pulmonary embolism.

Skull base aneurysms: a retrospective review of fifteen cases focusing on the involvement of internal carotid artery

Objective: To explore the diagnosis and clinical features of internal carotid artery aneurysm in the skull base. Methods: The data of 15 patients with internal carotid aneurysms in the skull base diagnosed and treated by digital subtraction angiography (DSA) or CT angiography (CTA) in the Provincial Hospital Affiliated to Shandong First Medical University from 1995 to 2017 were collected and analyzed. Among the 15 patients, 12 were males, and 3 were females, aging from 17 to 67 years old, with a median age of 44 years. Thirteen patients were diagnosed by DSA; the other two patients were diagnosed by CTA. Thirteen patients were diagnosed with pseudoaneurysm with the first symptom of epistaxis, in which eight patients underwent head trauma and 5 underwent radiotherapy of skull base tumor. The other two patients were diagnosed with true aneurysm presented headache and cranial nerve disorder. All patients were followed up for 2 to 12 years after treatment to see whether they were cured and survived. Results: Among the eight patients with a history of trauma, five patients were cured by embolization, two patients without embolization died of massive epistaxis, one patient died of progressive cerebral infarction after embolization. Among the five patients with radiotherapy of skull base tumor, one patient died of cerebral infarction after embolization, two patients died out of the hospital due to the recurrence of the primary tumor and intracranial invasion, one patient recovered well after embolization and surgical operation, one patient gave up treatment and died of massive hemorrhage out of hospital. In the other two patients with symptom of headache, one received embolization treatment outside the hospital after receiving mistake operation, and another one gave up treatment and died due to personal reasons. In total, four patients died in hospital, four died out of the hospital, and seven patients survived. Conclusions: Internal carotid artery aneurysm is a high-risk disease of anterior and middle skull base. For patients with epistaxis with a history of trauma and radiotherapy or patients with headaches and cranial nerve disorders, the possibility of the internal carotid artery aneurysm should be considered, in which DSA or CTA examination is essentially required for ensured diagnosis and disease evaluation.. The correct diagnosis and treatment by the otolaryngologist are crucial to the prognosis of the patient.

Pulmonary nodule enhancement in subtraction CT and dual-energy CT: A comparison study

ObjectiveTo compare nodule enhancement on subtraction CT iodine maps to that on dual-energy CT iodine maps using CT datasets acquired simultaneously. MethodsA previously-acquired set of lung subtraction and dual-energy CT maps consisting of thirty patients with 95 solid pulmonary nodules (≥4 mm diameter) was used. Nodules were annotated and segmented on CT angiography, and mean nodule enhancement in the iodine maps calculated. Three radiologists scored nodule visibility with both techniques on a 4-point scale. ResultsMean nodule enhancement was higher (p < 0.001) at subtraction CT (34.9 ± 12.9 HU) than at dual-energy CT (25.4 ± 21.0 HU). Nodule enhancement at subtraction CT was judged more often to be “highly visible” for each observers (p < 0.001) with an area under the curve of 0.81. ConclusionsSubtraction CT is able to depict iodine enhancement in pulmonary nodules better than dual-energy CT.

Assessment of Collateral Circulation Using Perfusion CT in Middle Cerebral Artery Thrombectomy-Treated Patients

Introduction: The prognostic value of leptomeningeal collateral circulation in thrombectomy-treated patients remains unclear. We evaluated the construct validity of assessing leptomeningeal collateral circulation using a new regional perfusion CT source image-based approach, the Perfusion Acquisition for THrombectomy Scale (PATHS). We also compared the prognostic value of PATHS with a further 6 scales based on various techniques: CT-angiography, perfusion CT, and digital subtraction angiography. Additionally, we studied the relationship between the scores for the different scales. Patients and Methods: We performed a retrospective study of consecutive patients with stroke and M1/terminal carotid occlusion treated with thrombectomy in our center. Leptomeningeal collateral circulation was prospectively evaluated using 7 scales: Tan and Miteff (CT Angiography); Calleja, Cao, American Society of Intervention and Therapeutic Neuroradiology/Society of Interventional Radiology, and PATHS (perfusion); and Christoforidis (Digital Subtraction Angiography). Correlations were studied using the Spearman method. Results: The study population comprised 108 patients. All scales predicted the modified Rankin Scale at 3 months (P ≤ .02) and all but 1 (Christoforidis) correlated with 24-hour brain infarct volume (P ≤ .02). These correlations were higher with PATHS (rho = −0.47, P < .001 for 3-month modified Rankin Scale; rho = −0.35, P < .001 for follow-up infarct volume). The multivariate analysis showed PATHS to be an independent predictor of modified Rankin Scale at 3 months less than equal to 2. A crosscorrelation analysis revealed a better correlation between scales that used the same techniques. Conclusions: PATHS can be used to assess leptomeningeal collateral circulation. PATHS had better prognostic value than other scales; therefore, it might be considered for assessment of leptomeningeal collateral circulation in candidates for thrombectomy. The moderate correlation between scales suggests that scores are not interchangeable.

CT Evaluation of Anatomical Variants of Hepatic Arteries: Impact on Endovascular Treatment Planning

The objective of this article is to examine the anatomical variants of hepatic arterial vascularization by 64-slice Angio-TC. When planning the treatment of patients with HCC that require surgery or endovascular therapy, it is useful to consider the variety of anatomical variants that are possible and it is the objective of this article to classify them using digital subtraction angiography (DSA) and CT. Examples of the application of these techniques in our hospital will also be illustrated. Angio-CT has the capability of visualizing these anatomical variants and therefore enabling the selection of an optimised surgical or endovascular treatment. Interventional radiology plays a key role in advanced endovascular treatment of liver tumours. The administration of drugs and/or chemo embolizing agents often requires super selective catheterization of arteries to the tumoral mass to preserve the healthy hepatic parenchyma.

Effect of different surgical options for posterior inferior cerebellar artery aneurysms

Objective To explore the clinical effect of various surgical operations on the treatment of posterior inferior cerebellar aneurysm. Methods The clinical data of 36 patients with a total of 36 posterior inferior cerebellar aneurysms admitted to Department of Neurosurgery, Weihai Central Hospital from October 2014 to May 2017 were retrospectively analyzed. Among all 36 patients, 22 underwent transcatheter embolization, 9 underwent aneurysm clipping using craniotomy, and the remaining 5 underwent cerebral artery bypass surgery combined with transcatheter embolization. The treatment outcome was evaluated using Glasgow outcome scale(GOS) at discharge and modified Rankin scale (mRS) at follow-up. Imaging outcome was evaluated by digital subtraction angiography (DSA) or CT angiography (CTA). Results Of the 22 patients undergoing transcatheter embolization, 21 were completely embolized. Aneurysms in 8 of the 9 patients were successfully clipped. Successful vascular anastomosis and complete embolization were achieved in 5 patients undergoing cerebral artery bypass surgery combined with transcatheter embolization. Among the 36 patients, 9 cases developed non-newly developed postoperative neurological deficits and 1 died. Thirty-five patients were discharged with GOS grade Ⅴ in 18 cases, Ⅳ in 14 cases and Ⅲ in 3 cases. Thirty-five cases were reexamined by CTA or DSA at 2 weeks post operation, which indicated disappearance of aneurysm. At follow-up of 3 months to 1 year post operation, 3 cases(8.6%) of aneurysm recurrence were reported which had undergone interventional embolization, and the rest of 32 patients had no recurrence. Thirty-five patients were followed up for 1 year. The mRS score was 0-1 in 21 cases, 2 in 8, 3 in 3, 4 in 1 and 5 in 1 case. The rate of good outcome were 85.3% (29/34) and there was 1 patient lost to follow-up. Conclusions According to the specific condition, interventional embolization, craniotomy of aneurysm clipping, or cerebral artery bypass surgery combined with transcatheter embolization could be performed to treat the posterior inferior cerebellar aneurysm, which might lead to relatively good clinical outcome with low incidence of aneurysm recurrence. Key words: Incranial aneurysm; Embolization, therapeutic; Microsurgery; Treatment outcome; Inferior cerebellar artery

Abstract No. 482 Utility of touchless image navigation in interventional radiology procedures

Intraprocedural image review during interventional radiology (IR) procedures is common, but current practice requires the operator to either leave the sterile field to use a computer or to direct an assistant while observing. An emerging technology platform (TIPSO; NZ Technologies, Vancouver, Canada) enables ergonomic touchless image interaction at bedside by utilizing 3D motion sensing. This study assesses the technology’s applicability in daily practice and identifies procedural steps to which the technology may contribute. The technology was evaluated in IR procedures that typically involve substantial intraprocedural image review. After each case, the operator completed a survey that records usability data on: i) the type of procedure and imaging interaction; ii) the frequency with which the technology and its specific functions were engaged; and, iii) workflow parameters. The operator also rated the technology’s impact in factors that influence patient outcomes using a 7-point Likert scale [1-most negatively; 4-neutral; 7-most positively]. Data were collected in n = 11 cases (bronchial artery embolization, uterine fibroid embolization, and pulmonary embolism (PE) thrombectomy) for reviewing images in PACS, CT and digital subtraction angiography. The technology was used 5.0 ± 3.4 times/case, most commonly for device navigation (n = 11; 3.8 ± 2.5 times/case), followed by preprocedural setup (n = 6; 1.2 ± 0.4 times/case), and device deployment (n = 1; 2 times). The technology was employed mostly for scrolling (n = 11), followed by changing series (n = 5), and magnification and window/level adjustment (n = 2). Operators rated a Likert score as: 6.7 ± 0.5 in understanding of the patient’s anatomy; 6.0 ± 1.4 in precision of device navigation; 6.0 ± 1.4 in overall workflow; and, 6.6 ± 0.8 in operator’s cognitive focus. Particularly, the technology was useful by enabling bedside image review in emergent cases (i.e., PE) for a prompt determination of an actionable step. Consistent use of the technology was seen in various cases, with a favorable rating for the impact in improving outcomes. Continuing studies will determine the role of touchless image navigation for routine use in IR.

Automatic Extraction of Abnormalities on Temporal CT Subtraction Images Using Sparse Coding and 3D-CNN

Automatic Extraction of Abnormalities on Temporal CT Subtraction Images Using Sparse Coding and 3D-CNN

Automated CT registration tool improves sensitivity to change in ventricular volume in patients with shunts and drains.

CT is the mainstay imaging modality for assessing change in ventricular volume in patients with ventricular shunts or external ventricular drains (EVDs). We evaluated the performance of a novel fully automated CT registration and subtraction method to improve reader accuracy and confidence compared with standard CT. In a retrospective evaluation of 49 ventricular shunt or EVD patients who underwent sequential head CT scans with an automated CT registration tool (CT CoPilot), three readers were assessed on their ability to discern change in ventricular volume between scans using standard axial CT images versus reformats and subtraction images generated by the registration tool. The inter-rater reliability among the readers was calculated using an intraclass correlation coefficient (ICC). Bland-Altman tests were performed to determine reader performance compared to semi-quantitative assessment using the bifrontal horn and third ventricular width. McNemar's test was used to determine whether the use of the registration tool increased the reader's level of confidence. Inter-rater reliability was higher when using the output of the registration tool (single measure ICC of 0.909 with versus 0.755 without the tool). Agreement between the readers' assessment of ventricular volume change and the semi-quantitative assessment improved with the registration tool (limits of agreement 4.1 vs 4.3). Furthermore, the tool improved reader confidence in determining increased or decreased ventricular volume (p < 0.001). Automated CT registration and subtraction improves the reader's ability to detect change in ventricular volume between sequential scans in patients with ventricular shunts or EVDs. Our automated CT registration and subtraction method may serve as a promising generalizable tool for accurate assessment of change in ventricular volume, which can significantly affect clinical management.