Assessment and validation of glottic motion using cone-beam CT and real-time cine MRI

PURPOSE

This study aimed to assess the margin for the planning target volume (PTV) using the Van Herk formula. We then validated the proposed margin by real-time magnetic resonance imaging (MRI).

METHODS

An analysis of cone-beam computed tomography (CBCT) data from early glottic cancer patients was performed to evaluate organ motion. Deformed clinical target volumes (CTV) after rigid registration were acquired using the Velocity program (Varian Medical Systems, Palo Alto, CA, USA). Systematic (Σ) and random errors (σ) were evaluated. The margin for the PTV was defined as 2.5 Σ + 0.7 σ according to the Van Herk formula. To validate this margin, we accrued healthy volunteers. Sagittal real-time cine MRI was conducted using the ViewRay system (ViewRay Inc., Oakwood Village, OH, USA). Within the obtained sagittal images, the vocal cord was delineated. The movement of the vocal cord was summed up and considered as the internal target volume (ITV). We then assessed the degree of overlap between the ITV and the PTV (vocal cord plus margins) by calculating the volume overlap ratio, represented as (ITV∩PTV)/ITV.

RESULTS

CBCTs of 17 early glottic patients were analyzed. Σ and σ were 0.55 and 0.57 for left-right (LR), 0.70 and 0.60 for anterior-posterior (AP), and 1.84 and 1.04 for superior-inferior (SI), respectively. The calculated margin was 1.8 mm (LR), 2.2 mm (AP), and 5.3 mm (SI). Four healthy volunteers participated for validation. A margin of 3 mm (AP) and 5 mm (SI) was applied to the vocal cord as the PTV. The average volume overlap ratio between ITV and PTV was 0.92 (range 0.85-0.99) without swallowing and 0.77 (range 0.70-0.88) with swallowing.

CONCLUSION

By evaluating organ motion by using CBCT, the margin was 1.8 (LR), 2.2 (AP), and 5.3 mm (SI). The margin acquired using CBCT fitted well in real-time cine MRI. Given that swallowing during radiotherapy can result in a substantial displacement, it is crucial to consider strategies aimed at minimizing swallowing and related motion.

Detailed Anatomy of Bridging Veins Around the Foramen Magnum: a Multicenter Study Using Three-dimensional Angiography

BACKGROUND AND PURPOSE

There has been limited literature regarding the bridging veins (BVs) of the medulla oblongata around the foramen magnum (FM). The present study aims to analyze the normal angioarchitecture of the BVs around the FM using slab MIP images of three-dimensional (3D) angiography.

METHODS

We collected 3D angiography data of posterior fossa veins and analyzed the BVs around the FM using slab MIP images. We analyzed the course, outlet, and number of BVs around the FM. We also examined the detection rate and mean diameter of each BV.

RESULTS

Of 57 patients, 55 patients (96%) had any BV. The median number of BVs was two (range: 0-5). The BVs originate from the perimedullary veins and run anterolaterally to join the anterior condylar vein (ACV), inferior petrosal sinus, sigmoid sinus, or jugular bulb, inferolaterally to join the suboccipital cavernous sinus (SCS), laterally or posterolaterally to join the marginal sinus (MS), and posteriorly to join the MS or occipital sinus. We classified BVs into five subtypes according to the draining location: ACV, jugular foramen (JF), MS, SCS, and cerebellomedullary cistern (CMC). ACV, JF, MS, SCS, and CMC BVs were detected in 11 (19%), 18 (32%), 32 (56%), 20 (35%), and 16 (28%) patients, respectively. The mean diameter of the BVs other than CMC was 0.6 mm, and that of CMC BV was 0.8 mm.

CONCLUSION

Using venous data from 3D angiography, we detected FM BVs in most cases, and the BVs were connected in various directions.

Evaluating AI-generated CBCT-based synthetic CT images for target delineation in palliative treatments of pelvic bone metastasis at conventional C-arm linacs

PURPOSE

One-table treatments with treatment imaging, preparation and delivery occurring at one treatment couch, could increase patients' comfort and throughput for palliative treatments. On regular C-arm linacs, however, cone-beam CT (CBCT) imaging quality is currently insufficient. Therefore, our goal was to assess the suitability of AI-generated CBCT based synthetic CT (sCT) images for target delineation and treatment planning for palliative radiotherapy.

MATERIALS AND METHODS

CBCTs and planning CT-scans of 22 female patients with pelvic bone metastasis were included. For each CBCT, a corresponding sCT image was generated by a deep learning model in ADMIRE 3.38.0. Radiation oncologists delineated 23 target volumes (TV) on the sCTs (TVsCT) and scored their delineation confidence. The delineations were transferred to planning CTs and manually adjusted if needed to yield gold standard target volumes (TVclin). TVsCT were geometrically compared to TVclin using Dice coefficient (DC) and Hausdorff Distance (HD). The dosimetric impact of TVsCT inaccuracies was evaluated for VMAT plans with different PTV margins.

RESULTS

Radiation oncologists scored the sCT quality as sufficient for 13/23 TVsCT (median: DC = 0.9, HD = 11 mm) and insufficient for 10/23 TVsCT (median: DC = 0.7, HD = 34 mm). For the sufficient category, remaining inaccuracies could be compensated by +1 to +4 mm additional margin to achieve coverage of V95% > 95% and V95% > 98%, respectively in 12/13 TVsCT.

CONCLUSION

The evaluated sCT quality allowed for accurate delineation for most targets. sCTs with insufficient quality could be identified accurately upfront. A moderate PTV margin expansion could address remaining delineation inaccuracies. Therefore, these findings support further exploration of CBCT based one-table treatments on C-arm linacs.

An International Survey of Practices in the Investigation and Endoscopic Treatment of Peripheral Pulmonary Lesions amongst Interventional Bronchoscopists

INTRODUCTION

The investigation of peripheral pulmonary lesions (PPLs) can be challenging. Several bronchoscopic modalities have been developed to reach and biopsy PPL but the level of adoption of these techniques by interventional pulmonologists (IPs) is unknown. This international survey was conducted to describe current practices in PPL investigation among IP.

METHODS

This survey was sent to all members of the World Association for Bronchology and Interventional Pulmonology, Canadian Thoracic Society Procedures Assembly, AABIP, and the Groupe d'Endoscopie Thoracique et Interventionnel Francophone. The survey was composed of 48 questions and three clinical cases to establish a portrait of modalities used to investigate and treat PPL by IP around the world.

RESULTS

Three hundred and twelve IP responded to the survey. Most of them practice in Europe (n = 122), North America (n = 97), and Asia (n = 49). Half of responders perform more than 100 endoscopic procedures for PPL annually. General anesthesia and conscious sedation are used in similar proportions (53% and 47%, respectively). Rapid on site evaluation (ROSE) is used when sampling PPL by 42%. Radial EBUS (69%), fluoroscopy (55%), and electromagnetic navigation (27%) are the most widely used techniques. Most IP combine techniques (89%). Robotic bronchoscopy (15%) and cone-beam CT (8%) are almost exclusively used in the USA where, respectively, 60% and 37% of respondents reported using these modalities. Ten percent of IP currently had access to endoscopic treatment modalities for PPL. However, half of the remaining IP plan to acquire an endoscopic treatment modality in the next 2 years.

CONCLUSION

Available techniques and practices worldwide vary significantly regarding PPL investigation and treatment.

Artifact suppression for breast specimen imaging in micro CBCT using deep learning

BACKGROUND

Cone-beam computed tomography (CBCT) has been introduced for breast-specimen imaging to identify a free resection margin of abnormal tissues in breast conservation. As well-known, typical micro CT consumes long acquisition and computation times. One simple solution to reduce the acquisition scan time is to decrease of the number of projections, but this method generates streak artifacts on breast specimen images. Furthermore, the presence of a metallic-needle marker on a breast specimen causes metal artifacts that are prominently visible in the images. In this work, we propose a deep learning-based approach for suppressing both streak and metal artifacts in CBCT.

METHODS

In this work, sinogram datasets acquired from CBCT and a small number of projections containing metal objects were used. The sinogram was first modified by removing metal objects and up sampling in the angular direction. Then, the modified sinogram was initialized by linear interpolation and synthesized by a modified neural network model based on a U-Net structure. To obtain the reconstructed images, the synthesized sinogram was reconstructed using the traditional filtered backprojection (FBP) approach. The remaining residual artifacts on the images were further handled by another neural network model, ResU-Net. The corresponding denoised image was combined with the extracted metal objects in the same data positions to produce the final results.

RESULTS

The image quality of the reconstructed images from the proposed method was improved better than the images from the conventional FBP, iterative reconstruction (IR), sinogram with linear interpolation, denoise with ResU-Net, sinogram with U-Net. The proposed method yielded 3.6 times higher contrast-to-noise ratio, 1.3 times higher peak signal-to-noise ratio, and 1.4 times higher structural similarity index (SSIM) than the traditional technique. Soft tissues around the marker on the images showed good improvement, and the mainly severe artifacts on the images were significantly reduced and regulated by the proposed.

METHOD

CONCLUSIONS

Our proposed method performs well reducing streak and metal artifacts in the CBCT reconstructed images, thus improving the overall breast specimen images. This would be beneficial for clinical use.

Prospects for daily online adaptive radiotherapy for cervical cancer: Auto-contouring evaluation and dosimetric outcomes

BACKGROUND

Training senior radiation therapists as "adapters" to manage influencers and target editing is critical in daily online adaptive radiotherapy (oART) for cervical cancer. The purpose of this study was to evaluate the accuracy and dosimetric outcomes of automatic contouring and identify the key areas for modification.

METHODS

A total of 125 oART fractions from five postoperative cervical cancer patients and 140 oART fractions from five uterine cervical cancer patients treated with daily iCBCT-guided oART were enrolled in this prospective study. The same adaptive treatments were replanned using the Ethos automatic contours workflow without manual contouring edits. The clinical target volume (CTV) was subdivided into several separate regions, and the average surface distance dice (ASD), centroid deviation, dice similarity coefficient (DSC), and 95% Hausdorff distance (95% HD) were used to evaluate contouring for the above portions. Dosimetric results from automatic oART plans were compared to supervised oART plans to evaluate target volumes and organs at risk (OARs) dose changes.

RESULTS

Overall, the paired CTV had high overlap rates, with an average DSC value greater than 0.75. The uterus had the largest consistency differences, with ASD, centroid deviation, and 95% HD being 2.67 ± 1.79 mm, 17.17 ± 12 mm, and 10.45 ± 5.68 mm, respectively. The consistency differences of the lower nodal CTVleft and nodal CTVright were relatively large, with ASD, centroid deviation, and 95% HD being 0.59 ± 0.53 mm, 3.6 ± 2.67 mm, and 5.41 ± 4.08 mm, and 0.59 ± 0.51 mm, 3.6 ± 2.54 mm, and 4.7 ± 1.57 mm, respectively. The automatic online-adapted plan met the clinical requirements of dosimetric coverage for the target volume and improved the OAR dosimetry.

CONCLUSIONS

The accuracy of automatic contouring from the Ethos adaptive platform is considered clinically acceptable for cervical cancer, and the uterus, upper vaginal cuff, and lower nodal CTV are the areas that need to be focused on in training.

The positional consistency between guidewire and cannulated or solid screw in robot-assisted spinal internal fixation surgery

BACKGROUND

This study aimed to investigate the positional consistency between the guidewire and the screw in spinal internal fixation surgery.

METHODS

This study involved 64 patients who underwent robot-assisted thoracic or lumbar pedicle screw fixation surgery. Guidewires were inserted with the assistance of the Tirobot. Either cannulated screws or solid screws were inserted. Guidewire and screw accuracy was measured using CT images based on the Gertzbein and Robbins scale. The positional consistency between guidewire and screw was evaluated based on the fused CT images, which could graphically and quantitatively demonstrate the consistency. The consistency was evaluated based on a grading system that considered the maximum distance and angulation between the centerline of the guidewire and the screw in the region of the pedicle.

RESULTS

A total of 322 screws were placed including 206 cannulated ones and 116 solid ones. Based on the Gertzbein and Robbins scale, 97.5% of the guidewires were grade A, and 94.1% of the screws were grade A. Based on our guidewire-screw consistency scale, 85% in cannulated group, and 69.8% in solid group, were grade A. Both solid and cannulated screws may alter trajectory compared to the guidewires. The positional accuracy and guidewire-screw consistency in the solid screw group is significantly worse than that in the cannulated screw group. The cortical bone of the pedicle has a positive guide effect on either solid or cannulated screws.

CONCLUSION

The pedicle screws may alter trajectory despite the guidance of the guidewires. Solid screws show worse positional accuracy and guidewire-screw consistency compared with cannulated screws. Trial registration The study was retrospectively registered and approved by our center's institutional review board.

The accuracy of artificial intelligence deformed nodal structures in cervical online cone-beam-based adaptive radiotherapy

Background and Purpose

Online cone-beam-based adaptive radiotherapy (ART) adjusts for anatomical changes during external beam radiotherapy. However, limited cone-beam image quality complicates nodal contouring. Despite this challenge, artificial-intelligence guided deformation (AID) can auto-generate nodal contours. Our study investigated the optimal use of such contours in cervical online cone-beam-based ART.

Materials and Methods

From 136 adaptive fractions across 21 cervical cancer patients with nodal disease, we extracted 649 clinically-delivered and AID clinical target volume (CTV) lymph node boost structures. We assessed geometric alignment between AID and clinical CTVs via dice similarity coefficient, and 95% Hausdorff distance, and geometric coverage of clinical CTVs by AID planning target volumes by false positive dice. Coverage of clinical CTVs by AID contour-based plans was evaluated using D100, D95, V100%, and V95%.

Results

Between AID and clinical CTVs, the median dice similarity coefficient was 0.66 and the median 95 % Hausdorff distance was 4.0 mm. The median false positive dice of clinical CTV coverage by AID planning target volumes was 0. The median D100 was 1.00, the median D95 was 1.01, the median V100% was 1.00, and the median V95% was 1.00. Increased nodal volume, fraction number, and daily adaptation were associated with reduced clinical CTV coverage by AID-based plans.

Conclusion

In one of the first reports on pelvic nodal ART, AID-based plans could adequately cover nodal targets. However, physician review is required due to performance variation. Greater attention is needed for larger, daily-adapted nodes further into treatment.

Weight-bearing cone-beam CT with extensive coverage for volumetric imaging in adolescent idiopathic scoliosis: system implementation and initial validation

The study aimed to introduce a novel imaging method that generates large-coverage, weight-bearing, and 3D images of the whole spine. The proposed system comprises an X-ray tube, a flat panel detector, and a standing platform. The standing platform rotates the imaged subject, allowing for the acquisition of serial fluoroscopic images from different angles which can be used to create 3D images. To increase the longitudinal coverage, we apply a segmental scanning pattern in which the imaged region is scanned in segments and stitched. To address the issue of data inaccuracy between the segments, redundant areas are set at margins of the segmental images, and registration and stitching algorithms are applied. We conducted validation experiments to evaluate radiation dose and image quality. The dose was evaluated using the volume CT dose index (CTDIvol). For image quality evaluation, we measured the low-contrast and spatial resolution. Additionally, we conducted a clinical study consisting of 30 volunteers with adolescent idiopathic scoliosis who were imaged by our method, and the images were subjectively assessed based on image noise, artifacts, anatomical coverage, diagnostic confidence, and overall quality. The CTDIvol was 1.23 mGy, and the low-contrast resolution was 0.6% at 4 mm and the spatial resolution was 8 lp/cm. The clinical images were generally of good quality, with high scores for all factors evaluated. Our method successfully generates large-coverage, weight-bearing, and 3D images of the whole spine with high image quality and low radiation dose. It shows potential for wider clinical applications for various musculoskeletal conditions.

Convex triangular vs. cylindrical field of view: how does the shape of the FOV affect radiation dose?

OBJECTIVE

To compare the dosimetry between convex triangular fields of view (FOV) and similar dimension cylindrical FOVs of two cone-beam computed tomography (CBCT) models.

METHODS

Optically stimulated luminescence dosimeters (OSLDs) were placed in fiducial anatomical locations in an anthropomorphic phantom representing an adult head male for dosimetry scans. Convex triangular FOVs (100 × 80 mm/maxilla-mandible; 100 × 50 mm mandible; 100 × 50 mm/maxilla) from Veraviewepocs 3D R100 (J. Morita, Kyoto, Japan) (R100) and Veraview® X800 (J. Morita, Kyoto, Japan) (X800) and cylindrical FOVs from R100 and X800 (80 × 80 mm/maxilla-mandible; 80 × 50 mm/mandible; 80 × 50 mm/maxilla) were obtained, resulting in 12 different scan protocols. Equivalent doses for each relevant organ/tissue and the effective dose for each protocol were calculated. Mean effective doses were compared by the two-way analysis of variance (ANOVA) with Tukey's post hoc test to evaluate the effect of the FOV and device (α = 0.05).

RESULTS

The effective doses ranged between 69 and 324 μSv for the convex triangular FOVs and 76 and 332 μSv for the cylindrical FOVs. Convex triangular FOVs from the R100 device had effective doses 2.3 to 15.3% lower than their corresponding cylindrical FOVs with similar height (p < 0.05), and that difference ranged between 8.8 and 11.8% for the X800 device (p < 0.05).

CONCLUSION

Convex triangular fields of view delivered slightly lower effective doses than the cylindrical fields of view of similar dimensions in the R100 and X800 CBCT devices.

CLINICAL RELEVANCE

Understanding the influence of the image geometry formation in effective dose allows optimization to reduce patient dose.

Usefulness of tumor perfusion on cone-beam CT after hepatic arterial infusion port implantation for evaluating tumor response to hepatic arterial infusion chemotherapy in hepatocellular carcinoma treatment

PURPOSE

To compare tumor perfusion on cone-beam computed tomography (CBCT) after hepatic artery infusion port implantation with the tumor response to hepatic arterial infusion chemotherapy (HAIC) in patients with hepatocellular carcinoma (HCC).

METHODS

This retrospective study was conducted in patients with advanced HCC treated with HAIC from 2015 to 2020. We performed CBCT with contrast injection via a port on the day following implantation. We classified tumor perfusion on CBCT into three groups: hyperperfusion, isoperfusion, and hypoperfusion. We also evaluated tumor response to HAIC on follow-up images using RECIST 1.1 and compared it with tumor perfusion on CBCT.

RESULTS

This study included 206 tumors in 193 patients (mean: 60.5 years) with HCC. There were 100 hyperperfusion tumors (48.5%), 92 isoperfusion tumors (44.7%), and 14 hypoperfusion tumors (6.8%). The tumor response to HAIC included 10 tumors with a complete response (CR) (4.9%), 66 tumors with a partial response (32%), 60 tumors with stable disease (29.1%), and 70 tumors with progressive disease (34%). Hyperperfusion tumors had a 65% objective response rate (ORR) and a 92% disease control rate (DCR). Isoperfusion tumors had a 12% ORR and a 46.8% DCR, while hypoperfusion tumors had a 0% ORR and a 7.1% DCR. A CR was shown only in hyperperfusion tumors. The ORR and DCR of the three groups were different, with statistical significance (P < 0.001).

CONCLUSION

Hyperperfusion tumors on CBCT showed a better tumor response to HAIC, with a 65% ORR in patients with HCC. Tumor perfusion on CBCT after implantation of the hepatic arterial infusion port was associated with the tumor response to HAIC.

A new system for in-room image guidance in particle therapy at CNAO

This paper describes the design, installation, and commissioning of an in-room imaging device developed at the Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy). The system is an upgraded version of the one previously installed in 2014, and its design accounted for the experience gained in a decade of clinical practice of patient setup verification and correction through robotic-supported, off-isocenter in-room image guidance. The system's basic feature consists of image-based setup correction through 2D/3D and 3D/3D registration through a dedicated HW/SW platform. The major update with respect to the device already under clinical usage resides in the implementation of a functionality for extending the field of view of the reconstructed Cone Beam CT (CBCT) volume, along with improved overall safety and functional optimization. We report here details on the procedures implemented for system calibration under all imaging modalities and the results of the technical and preclinical commissioning of the device performed on two different phantoms. In the technical commissioning, specific attention was given to the assessment of the accuracy with which the six-degrees-of-freedom correction vector computed at the off-isocenter imaging position was propagated to the planned isocentric irradiation geometry. During the preclinical commissioning, the entire clinical-like procedure for detecting and correcting imposed, known setup deviation was tested on an anthropomorphic radioequivalent phantom. Results showed system performance within the sub-millimeter and sub-degree range according to project specifications under each imaging modality, making it ready for clinical application.

An evaluation of isocentre shift magnitude and treatment site on image-guided radiation therapy online decision analysis times

INTRODUCTION

The ability to capture more anatomical detail in cone-beam computed tomography (CBCT) imaging compared to kilovoltage (kV) and megavoltage (MV) imaging, has seen a documented shift towards CBCT image verification and staff adopting more extensive image analysis processes. The timeframe associated with assessing online CBCT images, termed the online decision analysis time, if drawn out, can affect treatment efficiency and accuracy. This study aimed to determine the current CBCT online decision analysis time at Radiation Oncology Princess Alexandra Ipswich Road (ROPAIR) and investigate the influence of isocentre shift magnitude and treatment site considerations on this timeframe.

METHODS

This retrospective clinical audit collected treatment parameters from 202 CBCT images over 2 treatment days. The online decision analysis time was calculated by subtracting the image acquisition timestamp from the image verification shift application timestamp. The quantitative data were analysed using mean, standard deviation, and range in the following categories: all CBCTs, CBCTs grouped by isocentre shift magnitude and CBCTs grouped by treatment site. Content analysis was performed on staff comments made during image analysis.

RESULTS

The average online decision analysis time was 2:37 ± 1:28 min. On average approximately, head and neck, spine and extremity treatment sites measured 1 min, pelvis, breast, and chest measured 2-3 min with abdomen measuring 4 min. Common categories reported in staff comments included anatomical changes, repositioning, and organs at risk size.

CONCLUSION

The results provide baseline online decision analysis times. Further refinement is required to determine if the image match method, treatment site considerations, and rotational discrepancies influence this timeframe.

Improved compact representation method for Monte Carlo phase spaces

Phase space files used in particle Monte Carlo simulations can be large, and thereby awkward to distribute and slow to load into memory. To circumvent this, compact source models and phase space representations have been developed. In this study, the aim is to increase the versatility of a previously presented method, based on principal component analysis whitening, by evaluating several modifications to the method on simulated cone-beam computed tomography projection images. Scaling the phase space components before whitening was seen to give the largest improvement and allowed for accurate modelling of phase spaces with a shifted detector and/or a bowtie filter present, configurations where the original method struggled. The modified method reproduced results using the original phase space to within a few percent both in energy fluence on the detector and in simulated projection and scatter images of a patient pelvis, without obvious position-dependence of the errors. Hence, the modified method was deemed sufficiently accurate for most applications relying on cone-beam computed tomography simulations. The final aim is to use the more versatile method for a broader range of phase space-based applications such as linear accelerator beam simulations and room shielding calculations.

Weight-bearing gantry-free cone-beam CT of the lumbar spine: Image quality analysis and dose efficiency

PURPOSE

The effect of static forces under load limits the prognostic value of lumbar spine CT in a horizontal position. Using a gantry-free scanner architecture, this study was designed to assess the feasibility of weight-bearing cone-beam CT (CBCT) of the lumbar spine and to establish the most dose-effective combination of scan parameters.

METHODS

Eight formalin-fixated cadaveric specimens were examined with a gantry-free CBCT system in upright position with the aid of a dedicated positioning backstop. Cadavers were scanned with eight combinations of tube voltage (102 or 117 kV), detector entrance dose level (high or low), and frame rates (16 or 30 fps). Five radiologists independently analyzed datasets for overall image quality and posterior wall assessability. Additionally, image noise and signal-to-noise ratio (SNR) were compared based on region-of-interest (ROI) measurements in the gluteal muscles.

RESULTS

Radiation dose ranged from 6.8 ± 1.6 (117 kV, dose level low, 16 fps) to 24.3 ± 6.3 mGy (102 kV, dose level high, 30 fps). Both image quality and posterior wall assessability were favored with 30 over 16 fps (all p ≤ 0.008). In contrast, both tube voltage (all p > 0.999) and dose level (all p > 0.096) did not significantly impact reader assessment. Image noise decreased considerably with higher frame rates (all p ≤ 0.040), while SNR ranged from 0.56 ± 0.03 to 1.11 ± 0.30 without a significant difference between scan protocols (all p ≥ 0.060).

CONCLUSIONS

Employing an optimized scan protocol, weight-bearing gantry-free CBCT of the lumbar spine allows for diagnostic imaging at reasonable radiation dose.

Clinical evaluation of synthetic computed tomography methods in adaptive proton therapy of lung cancer patients

Background and purpose

Efficient workflows for adaptive proton therapy are of high importance. This study evaluated the possibility to replace repeat-CTs (reCTs) with synthetic CTs (sCTs), created based on cone-beam CTs (CBCTs), for flagging the need of plan adaptations in intensity-modulated proton therapy (IMPT) treatment of lung cancer patients.

Materials and methods

Forty-two IMPT patients were retrospectively included. For each patient, one CBCT and a same-day reCT were included. Two commercial sCT methods were applied; one based on CBCT number correction (Cor-sCT), and one based on deformable image registration (DIR-sCT). The clinical reCT workflow (deformable contour propagation and robust dose re-computation) was performed on the reCT as well as the two sCTs. The deformed target contours on the reCT/sCTs were checked by radiation oncologists and edited if needed. A dose-volume-histogram triggered plan adaptation method was compared between the reCT and the sCTs; patients needing a plan adaptation on the reCT but not on the sCT were denoted false negatives. As secondary evaluation, dose-volume-histogram comparison and gamma analysis (2%/2mm) were performed between the reCT and sCTs.

Results

There were five false negatives, two for Cor-sCT and three for DIR-sCT. However, three of these were only minor, and one was caused by tumour position differences between the reCT and CBCT and not by sCT quality issues. An average gamma pass rate of 93% was obtained for both sCT methods.

Conclusion

Both sCT methods were judged to be of clinical quality and valuable for reducing the amount of reCT acquisitions.

Assessment of the canal anatomy of the premolar teeth in a selected Turkish population: a cone-beam computed tomography study

BACKGROUND

Teeth may have additional roots and a different number of root canals. Overlooked root canals may cause endodontic failure. The aim of this study was to investigate the prevalence of root canals and the number of roots of premolars in a selected Turkish population.

MATERIALS AND METHODS

A total of 2,570 teeth from 1,438 patients were evaluated. The cone-beam computed tomography scans of 1,055 maxillary and 1,515 mandibular premolars were examined.

RESULTS

Type IV root canal morphology was observed most frequently in maxillary first premolars (77%), and the rates of single and double channel formations were very similar (51% and 49%, respectively). Of the second maxillary premolars, 57.4% had Type I morphology, and 89.9% of the teeth were single-rooted, while 68.6% had a single root canal. The most common formation was Type I (85%) among mandibular first premolars, and a single root was observed in 95.6% of these teeth. In addition, 87% of the mandibular first premolars had a single root canal. The second mandibular premolars mostly had Type I (95.4%) formation, and 99.3% of the teeth were single-rooted, while 96.9% had a single root canal.

CONCLUSION

According to our findings, 51% of maxillary first premolars had a single root, 79.4% had two root canals, and 77% had Type IV (77%) formation. Maxillary second premolars mostly had Type I formation. In addition, a single root and single root canal formation were most common. Mandibular first premolars generally had a single root and single root canal formation, but 13% had two root canals, and 6.4% had Type V formation. More than 95% of mandibular second premolars had Type I formation.

Minimally Invasive Intracerebral Hemorrhage Evacuation Improves Pericavity Cerebral Blood Volume

Cerebral blood volume mapping can characterize hemodynamic changes within brain tissue, particularly after stroke. This study aims to quantify blood volume changes in the perihematomal parenchyma and pericavity parenchyma after minimally invasive intracerebral hemorrhage evacuation (MIS for ICH). Thirty-two patients underwent MIS for ICH with pre- and post-operative CT imaging and intraoperative perfusion imaging (DynaCT PBV Neuro, Artis Q, Siemens). The pre-operative and post-operative CT scans were segmented using ITK-SNAP software to calculate hematoma volumes and to delineate the pericavity tissue. Helical CT segmentations were registered to cone beam CT data using elastix software. Mean blood volumes were computed inside subvolumes by dilating the segmentations at increasing distances from the lesion. Pre-operative perihematomal blood volumes and post-operative pericavity blood volumes (PBV) were compared. In 27 patients with complete imaging, post-operative PBV significantly increased within the 6-mm pericavity region after MIS for ICH. The mean relative PBV increased by 21.6 and 9.1% at 3 mm and 6 mm, respectively (P = 0.001 and 0.016, respectively). At the 9-mm pericavity region, there was a 2.83% increase in mean relative PBV, though no longer statistically significant. PBV analysis demonstrated a significant increase in pericavity cerebral blood volume after minimally invasive ICH evacuation to a distance of 6 mm from the border of the lesion.

Evaluating the accuracy of automated cephalometric analysis based on artificial intelligence

BACKGROUND

The purpose of this study was to evaluate the accuracy of automatic cephalometric landmark localization and measurements using cephalometric analysis via artificial intelligence (AI) compared with computer-assisted manual analysis.

METHODS

Reconstructed lateral cephalograms (RLCs) from cone-beam computed tomography (CBCT) in 85 patients were selected. Computer-assisted manual analysis (Dolphin Imaging 11.9) and AI automatic analysis (Planmeca Romexis 6.2) were used to locate 19 landmarks and obtain 23 measurements. Mean radial error (MRE) and successful detection rate (SDR) values were calculated to assess the accuracy of automatic landmark digitization. Paired t tests and Bland‒Altman plots were used to compare the differences and consistencies in cephalometric measurements between manual and automatic analysis programs.

RESULTS

The MRE for 19 cephalometric landmarks was 2.07 ± 1.35 mm with the automatic program. The average SDR within 1 mm, 2 mm, 2.5 mm, 3 and 4 mm were 18.82%, 58.58%, 71.70%, 82.04% and 91.39%, respectively. Soft tissue landmarks (1.54 ± 0.85 mm) had the most consistency, while dental landmarks (2.37 ± 1.55 mm) had the most variation. In total, 15 out of 23 measurements were within the clinically acceptable level of accuracy, 2 mm or 2°. The rates of consistency within the 95% limits of agreement were all above 90% for all measurement parameters.

CONCLUSION

Automatic analysis software collects cephalometric measurements almost effectively enough to be acceptable in clinical work. Nevertheless, automatic cephalometry is not capable of completely replacing manual tracing. Additional manual supervision and adjustment for automatic programs can increase accuracy and efficiency.

Evaluating the accuracy of automated cephalometric analysis based on artificial intelligence

BACKGROUND

The purpose of this study was to evaluate the accuracy of automatic cephalometric landmark localization and measurements using cephalometric analysis via artificial intelligence (AI) compared with computer-assisted manual analysis.

METHODS

Reconstructed lateral cephalograms (RLCs) from cone-beam computed tomography (CBCT) in 85 patients were selected. Computer-assisted manual analysis (Dolphin Imaging 11.9) and AI automatic analysis (Planmeca Romexis 6.2) were used to locate 19 landmarks and obtain 23 measurements. Mean radial error (MRE) and successful detection rate (SDR) values were calculated to assess the accuracy of automatic landmark digitization. Paired t tests and Bland‒Altman plots were used to compare the differences and consistencies in cephalometric measurements between manual and automatic analysis programs.

RESULTS

The MRE for 19 cephalometric landmarks was 2.07 ± 1.35 mm with the automatic program. The average SDR within 1 mm, 2 mm, 2.5 mm, 3 and 4 mm were 18.82%, 58.58%, 71.70%, 82.04% and 91.39%, respectively. Soft tissue landmarks (1.54 ± 0.85 mm) had the most consistency, while dental landmarks (2.37 ± 1.55 mm) had the most variation. In total, 15 out of 23 measurements were within the clinically acceptable level of accuracy, 2 mm or 2°. The rates of consistency within the 95% limits of agreement were all above 90% for all measurement parameters.

CONCLUSION

Automatic analysis software collects cephalometric measurements almost effectively enough to be acceptable in clinical work. Nevertheless, automatic cephalometry is not capable of completely replacing manual tracing. Additional manual supervision and adjustment for automatic programs can increase accuracy and efficiency.

Scatter correction for cone-beam CT via scatter kernel superposition-inspired convolutional neural network

Objective.X-ray scatter leads to signal bias and degrades the image quality in Computed Tomography imaging. Conventional real-time scatter estimation and correction methods include the scatter kernel superposition (SKS) methods, which approximate x-ray scatter field as a convolution of the scatter sources and scatter propagation kernels to reflect the spatial spreading of scatter x-ray photons. SKS methods are fast to implement but generally suffer from low accuracy due to the difficulties in determining the scatter kernels.Approach.To address such a problem, this work describes a new scatter estimation and correction method by combining the concept of SKS methods and convolutional neural network. Unlike conventional SKS methods which estimate the scatter amplitude and the scatter kernel based on the value of an individual pixel, the proposed method generates the scatter amplitude maps and the scatter width maps from projection images through a neural network, from which the final estimated scatter field is calculated based on a convolution process.Main Results.By incorporating physics in the network design, the proposed method requires fewer trainable parameters compared with another deep learning-based method (Deep Scatter Estimation). Both numerical simulations and physical experiments demonstrate that the proposed SKS-inspired convolutional neural network outperforms the conventional SKS method and other deep learning-based methods in both qualitative and quantitative aspects.Significance.The proposed method can effectively correct the scatter-related artifacts with a SKS-inspired convolutional neural network design.

Cone-beam computed tomography-assisted percutaneous gastrostomy tube insertion in children with challenging anatomy

BACKGROUND

Percutaneous radiological gastrostomy tube insertion is a common procedure in children. An approach using ultrasound and fluoroscopy may not be feasible in patients with challenging anatomy; therefore, advanced techniques or other imaging modalities may be required.

OBJECTIVE

To describe our experience using cone-beam computed tomography (CT)-assisted percutaneous gastrostomy insertion in pediatric patients with challenging anatomy.

MATERIALS AND METHODS

A retrospective review was performed in children who underwent cone-beam CT-assisted percutaneous radiologic gastrostomy between January 2015 and July 2019. Indications, technique, outcomes, complications, and radiation dose (reference-point air kerma, air kerma area product) were assessed through chart and imaging review. Descriptive statistics only were used.

RESULTS

Twenty-seven procedures were attempted in 26 patients. Reasons for utilizing cone-beam CT guidance were high-positioned stomach (n = 10), interposing bowel loops and liver (n = 19), omphalocele (n = 1), severe scoliosis (n = 1), and ventriculoperitoneal shunt (n = 1). Technical success was 85% (23/27). Mean procedure time was 96 min (range 50-131 min). No safe access route into the stomach was encountered in four patients; three were referred for surgical gastrostomy and one had a successful re-attempt. Radiation dose data was obtained from 19 procedures (17 successful) with a total dose in successful procedures ranging from 8.1 to 63.6 mGy (average 26.2 mGy, median 24.9 mGy). The number of cone-beam CT acquisitions per procedure ranged from 1 to 4. Major complication frequency was 11% (3/27) (bleeding, peritonitis, and aspiration pneumonia); minor complication frequency was 3.7% (1/27).

CONCLUSION

This study shows that cone-beam CT guidance can be useful for assisting percutaneous radiologic gastrostomy in children with challenging anatomy.

Imaging of the human cochlea using micro-computed tomography before and after cochlear implantation: comparison with cone-beam computed tomography

PURPOSE

Analysis of cochlear structures and postoperative temporal bone (TB) imaging are gaining importance in the evaluation of cochlear implantation (CI°). Our aims were to explore the microarchitecture of human cochlea using micro-computed tomography (μCT), analyze electrode's placement inside cochlea after CI°, and compare pre-/post-implantation μCT scans with cone-beam CT (CBCT) scans of same TBs.

METHODS

Cadaveric TBs were scanned using μCT and CBCT then underwent CI° using straight electrodes. Thereafter, they underwent again μCT and CBCT-imaging.

RESULTS

Ten TBs were studied. μCT allowed visualization of scala tympani, scala vestibuli, basilar membrane, osseous spiral lamina, crista fenestrae, and spiral ligament. CBCT showed same structures except spiral ligament and crista fenestrae. After CI°, μCT and CBCT displayed the scalar location and course of electrode array within the cochlea. There were 7 cases of atraumatic electrode insertion and 3 cases of insertion trauma: basilar membrane elevation, electrode foldover with limited migration into scala vestibuli, and electrode kinking with limited migration into scala vestibuli. Insertion trauma was not correlated with cochlea's size or crista's maximal height but with round window membrane diameter. Resolution of μCT was higher than CBCT but electrode artifacts were similar.

CONCLUSIONS

μCT was accurate in visualizing cochlear structures, and course and scalar position of electrode array inside cochlea with any possible trauma to cochlea or array. CBCT offers a good alternative to μCT in clinical practice for cochlear imaging and evaluation of CI°, with lower radiation and higher resolution than multi-slice CT. Difficulties related to non-traumatic CI° are multifactorial.

[Role of computed tomography in the preoperative diagnosis of otosclerosis]

BACKGROUND

Otosclerosis is an osteodystrophy of the otic capsule and presents with progressive conductive hearing loss. Imaging studies, especially computed tomography (CT) and cone-beam CT, have gained increased relevance in the diagnosis of otosclerosis.

OBJECTIVE

This study investigated whether there is a correlation between the extent of otosclerosis in high-resolution or cone-beam CT and hearing loss in pure-tone audiometry.

MATERIALS AND METHODS

Based on an existing classification of otosclerotic foci, a classification was established. Preoperative CT scans of patients undergoing stapedotomy between 2015 and 2019 were evaluated and classified by two independent otorhinolaryngologists. The preoperative pure-tone audiograms were analysed and compared to the results of CT.

RESULTS

A total of 168 CT studies (i.e., 168 ears) in 156 patients with intraoperatively confirmed otosclerosis were included in our study. A correlation between the extent of the otosclerotic focus or the calculated scores and hearing loss in pure-tone audiometry (air conduction, bone conduction and air-bone-gap) could not be proven.

CONCLUSION

Preoperative CT is not obligatory. However, preoperative imaging using CT or cone-beam CT can be helpful to confirm the diagnosis and exclude other middle or inner ear pathologies as well as in planning of the surgical procedure in the overall context of otoscopy and audiometry. A correlation with the degree of hearing impairment could not be demonstrated and remains unclear.

The impact of high-resolution cone-beam CT findings on decision-making for the treatment of unruptured middle cerebral artery aneurysms

Even with the advent of endovascular treatment for intracranial aneurysms, microsurgical clipping continues to play a significant role in the treatment of middle cerebral artery (MCA) aneurysms. Securing perforators around unruptured intracranial aneurysms (UIAs) is essential for minimizing procedural risks in each treatment option. Therefore, we herein investigated whether the findings of high-resolution cone-beam computed tomography (HR-CBCT) have an impact on decision-making for the treatment of MCA UIAs. Patients with MCA UIAs between October 2017 and September 2021 were consecutively recruited for this study. All patients underwent HR-CBCT and 3D-DSA before treatment. The imaging quality of both modalities to visualize the microvasculature around aneurysms was evaluated. Specific findings on the microvasculature surrounding aneurysms on HR-CBCT were investigated to facilitate microsurgical clipping. Fifty-two MCA UIAs were treated, including 43 by microsurgical clipping and 9 by endovascular approaches. The overall imaging quality of HR-CBCT was superior to that of 3D-DSA. Regarding microsurgical insights, sensitivity and specificity for the visualization of small vessels around aneurysms were 79 and 100%, respectively, using HR-CBCT, and 57 and 93%, respectively, using 3D-DSA. The presence of a low-density band between adhesive vessels and aneurysm sacs was indicative of successful and safe microsurgical dissection between these structures. HR-CBCT enabled visualization of the intracranial microvasculature around MCA UIAs at the submillimeter level in vivo. In cases in which the tight adhesion of the microvasculature to the aneurysm sac is indicated by HR-CBCT, an endovascular approach may be considered in order to avoid the risks associated with securing perforators.

Measuring standing hindfoot alignment: reliability of different approaches in conventional x-ray and cone-beam CT

INTRODUCTION

Currently there is no consensus how hindfoot alignment (HA) should be assessed in CBCT scans. The aim of this study is to investigate how the reliability is affected by the anatomical structures chosen for the measurement.

MATERIALS AND METHODS

Datasets consisting of a Saltzman View (SV) and a CBCT of the same foot were acquired prospectively and independently assessed by five raters regarding HA. In SVs the HA was estimated as follows: transversal shift between tibial shaft axis and heel contact point (1); angle between tibial shaft axis and a tangent at the medial (2) or lateral (3) calcaneal wall. In CBCT the HA was estimated as follows: transversal shift between the centre of the talus and the heel contact point (4); angle between a perpendicular line and a tangent at the medial (5) or lateral (6) calcaneal wall; angle between the distal tibial surface and a tangent at the medial calcaneal wall (7). Intraclass correlation coefficients (ICC) were calculated to assess inter-rater reliability. A linear regression was performed to compare the different measurement regarding their correlation.

RESULTS

32 patients were included in the study. The ICCs for the measurements 1-7 were as follows: (1) 0.924 [95% CI 0.876-0.959] (2) 0.533 [95% CI 0.377-0.692], (3) 0.553 [95% CI 0.399-0.708], (4) 0.930 [95% CI 0.866-0.962], (5) 0.00 [95% CI - 0.111 to 0.096], (6) 0.00 [95% CI - 0.103 to 0.111], (7) 0.152 [95% CI 0.027-0.330]. A linear regression between measurement 1 and 4 showed a correlation of 0.272 (p = 0.036).

CONCLUSIONS

It could be shown that reliability of measuring HA depends on the investigated anatomical structure. Placing a tangent along the calcaneus (2, 3, 5, 6, 7) was shown to be unreliable, whereas determining the weight-bearing heel point (1, 4) appeared to be a reliable approach. The correlation of the measurement workflows is significant (p = 0.036), but too weak (0.272) to be used clinically.

Fluoroscopic imaging: New advances

Today's orthopedic surgery could not be imagined without intraoperative x-ray-based imaging. This enables surgeons to assess operative interim steps as well as the result before wound closure and finishing the procedure. Although there have been mobile C-arms used for decades, there are recent advances that do not only affect the quality of the imaging itself but also the way, the information is processed and presented. These very exciting developments will change the integration of imaging into the surgical workflows, giving options of augmented reality, reduction of radiation dose, automatized acquisition and analysis of images and low-level guidance in procedures. This paper gives a review of current innovations and possible future trends in fluoroscopic 2D and 3D imaging.

Truncation effect reduction for fast iterative reconstruction in cone-beam CT

Background

Iterative reconstruction for cone-beam computed tomography (CBCT) has been applied to improve image quality and reduce radiation dose. In a case where an object’s actual projection is larger than a flat panel detector, CBCT images contain truncated data or incomplete projections, which degrade image quality inside the field of view (FOV). In this work, we propose truncation effect reduction for fast iterative reconstruction in CBCT imaging.

Methods

The volume matrix size of the FOV and the height of projection images were extrapolated to a suitable size. These extended projections were reconstructed by fast iterative reconstruction. Moreover, a smoothing parameter for noise regularization in iterative reconstruction was modified to reduce the accumulated error while processing. The proposed work was evaluated by image quality measurements and compared with conventional filtered backprojection (FBP). To validate the proposed method, we used a head phantom for evaluation and preliminarily tested on a human dataset.

Results

In the experimental results, the reconstructed images from the head phantom showed enhanced image quality. In addition, fast iterative reconstruction can be run continuously while maintaining a consistent mean-percentage-error value for many iterations. The contrast-to-noise ratio of the soft-tissue images was improved. Visualization of low contrast in the ventricle and soft-tissue images was much improved compared to those from FBP using the same dose index of 5 mGy.

Conclusions

Our proposed method showed satisfactory performance to reduce the truncation effect, especially inside the FOV with better image quality for soft-tissue imaging. The convergence of fast iterative reconstruction tends to be stable for many iterations.

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.

Practical workflow for arbitrary non-circular orbits for CT with clinical robotic C-arms

Non-circular orbits in cone-beam CT (CBCT) imaging are increasingly being studied for potential benefits in field-of-view, dose reduction, improved image quality, minimal interference in guided procedures, metal artifact reduction, and more. While modern imaging systems such as robotic C-arms are enabling more freedom in potential orbit designs, practical implementation on such clinical systems remains challenging due to obstacles in critical stages of the workflow, including orbit realization, geometric calibration, and reconstruction. In this work, we build upon previous successes in clinical implementation and address key challenges in the geometric calibration stage with a novel calibration method. The resulting workflow eliminates the need for prior patient scans or dedicated calibration phantoms, and can be conducted in clinically relevant processing times.

Utility of Cone-Beam CT for Bronchial Artery Embolization and Chemoinfusion: A Single-Institution Retrospective Case Series

PURPOSE

To describe the technique and document utility of adjunctive cone-beam CT (CBCT) in patients undergoing bronchial artery embolization (BAE) or chemoinfusion (BAC).

MATERIALS AND METHODS

Between August 2010 and February 2021, 26 patients (62 bronchial arteries) were evaluated with CBCT in addition to the usual digital subtraction angiography (DSA) during BAE or BAC. 19 patients (43 arteries) underwent BAE for hemoptysis; 7 patients (19 arteries) had BAC for palliation of lung malignancy. Retrospective review of procedural reports and the archived DSA and CBCT images was assessed for (1) whether CBCT findings added unique diagnostic information prior to treatment of target arteries compared to DSA alone; and (2) whether these unique CBCT findings led to modification of embolization or chemoinfusion technique.

RESULTS

In 61 of 62 (98%) interrogated bronchial arteries, CBCT provided additional unique diagnostic information over planar DSA, primarily cross-sectional assessment of the spinal canal for spinal arteries. In 46/62 (74%) of the bronchial arteries the unique information did not lead to a change in therapeutic technique. In 15 bronchial arteries (24%), the added information from CBCT led to change in embolization and/or chemoinfusion technique. Embolization of one small unrecognized spinal artery branch (1.6%), which was missed intra-procedurally but retrospectively seen on CBCT led to transient spinal cord ischemia.

CONCLUSIONS

These results suggest that adjunctive use of CBCT technique may improve diagnostic confidence from information provided by DSA in nearly all cases of BAE and BAC leading to improved therapeutic targeting or change in technique of embolization or chemoinfusion.

Software-Automated Implant Detection for Intraoperative 3D Imaging-First Clinical Evaluation on 214 Data Sets

Previous studies have demonstrated a frequent occurrence of screw/K-wire malpositioning during surgical fracture treatment under 2D fluoroscopy and a correspondingly high revision rate as a result of using intraoperative 3D imaging. In order to facilitate and accelerate the diagnosis of implant malpositioning in 3D data sets, this study investigates two versions of an implant detection software for mobile 3D C-arms in terms of their detection performance based on comparison with manual evaluation. The 3D data sets of patients who had received surgical fracture treatment at five anatomical regions were extracted from the research database. First, manual evaluation of the data sets was performed, and the number of implanted implants was assessed. For 25 data sets, the time required by four investigators to adjust each implant was monitored. Subsequently, the evaluation was performed using both software versions based on the following detection parameters: true-positive-rate, false-negative-rate, false-detection-rate and positive predictive value. Furthermore, the causes of false positive and false negative detected implants depending on the anatomical region were investigated. Two hundred fourteen data sets with overall 1767 implants were included. The detection parameters were significantly improved (p<.001) from version 1 to version 2 of the implant detection software. Automatic evaluation required an average of 4.1±0.4 s while manual evaluation was completed in 136.15±72.9 s (p<.001), with a statistically significant difference between experienced and inexperienced users (p=.005). In summary, version 2 of the implant detection software achieved significantly better results. The time saved by using the software could contribute to optimizing the intraoperative workflow.

A novel use for routine CBCT imaging during radiotherapy to detect COVID-19

INTRODUCTION

Thoracic CT is a useful tool in the early diagnosis of patients with COVID-19. Typical appearances include patchy ground glass shadowing. Thoracic radiotherapy uses daily cone beam CT imaging (CBCT) to check for changes in patient positioning and anatomy prior to treatment through a qualitative assessment of lung appearance by radiographers. Observation of changes related to COVID-19 infection during this process may facilitate earlier testing improving patient management and staff protection.

METHODS

A tool was developed to create overview reports for all CBCTs for each patient throughout their treatment. Reports contain coronal maximum intensity projection (MIP's) of all CBCTs and plots of lung density over time. A single therapeutic radiographer undertook a blinded off-line audit that reviewed 150 patient datasets for tool optimisation in which medical notes were compared to image findings. This cohort included 75 patients treated during the pandemic and 75 patients treated between 2014 and 2017. The process was repeated retrospectively on a subset of the 285 thoracic radiotherapy patients treated between January-June 2020 to assess the efficiency of the tool and process.

RESULTS

Three patients in the n = 150 optimisation cohort had confirmed COVID-19 infections during their radiotherapy. Two of these were detected by the reported image assessment process. The third case was not detected on CBCT due to minimal density changes in the visible part of the lungs. Within the retrospective cohort four patients had confirmed COVID-19 based on RT-PCR tests, three of which were retrospectively detected by the reported process.

CONCLUSION

The preliminary results indicate that the presence of COVID-19 can be detected on CBCT by therapeutic radiographers.

IMPLICATIONS FOR PRACTICE

This process has now been extended to clinical service with daily assessments of all thoracic CBCTs. Changes noted are referred for oncologist review.

Development of a multi-stage model for intelligent and quantitative appraising of skeletal maturity using cervical vertebras cone-beam CT images of Chinese girls

PURPOSE

Nowadays, the integration of Artificial intelligence algorithms and quantified radiographic imaging-based diagnostic procedures is hailing amplified deliberation particularly in assessment of skeletal maturity. So we intend to formulate a logistic regression model for intelligent and quantitative estimation of Fishman skeletal maturation index (SMI) based on the parameters attained from the cervical vertebrae CBCT images of Chinese girls.

METHODS

From 709 hand wrist radiographs and CBCT images, 447 samples were randomly selected (called as G1) to build a logistic regression model. The reliability and reproducibility were assessed by the intraclass correlation coefficient (ICC) and weighted Cohen's kappa, followed by Spearman's rank correlation coefficient to identify the parameters significantly associated with the SMI. Two hundred and sixty-two other subjects (named G2) were recruited for external examination of the models by direct visual comparison and the receiver operating characteristic (ROC) curve. In cases of confusion and mispredictions, the model was modified to improve the consistency.

RESULTS

Five significant parameters (Chronological age, C3 height (H3)[Formula: see text], C4 upper width (UW4), C4 lower width (LW4), and the ratio of posterior height to lower width of C4 ([Formula: see text]) were administered into logistic regression model. Despite total agreement percentage which was 84% (total AUC = 0.92), unsatisfactory performance was noticed for the 6th and 8th stages which were confused with their neighboring stages. After adjustments of the models, the total agreement percentage and AUC were upgraded to 88% and 0.96, respectively.

CONCLUSION

Consistency and fitness evaluation of our models demonstrated adequate prediction percentage and reliability for automated classification of skeletal maturation. The presented constructed logistic regression model has the potential to serve as a maturity evaluation index in clinical craniofacial orthopedics in Chinese girls. The proposed model in this study showed promising strength for being expended in the event of other clinical multi-stage conditions.

Reliability of cone beam CT for morphometry of nasolabial soft tissue in patients with skeletal class III malocclusion: A qualitative and quantitative analysis

OBJECTIVE

To assess reliability of cone-beam CT (CBCT) for nasolabial soft tissue measurements in patients with skeletal class III malocclusion based on 3-dimensional (3D) facial scanner results.

METHODS

CBCT and 3D facial scan images of 20 orthognathic patients are used in this study. Eleven soft tissue landmarks and 15 linear and angular measurements are identified and performed. For qualitative evaluation, Shapiro-Wilk test and Bland-Altman plots are applied to analyze the equivalence of the measurements derived from these two kinds of images. To quantify specific deviation of CBCT measurements from facial scanner, the latter is set as a benchmark, and mean absolute difference (MAD) and relative error magnitude (REM) for each variable are also calculated.

RESULTS

Statistically significant differences are observed in regions of nasal base and lower lip vermilion between two methods. MAD value for all length measurements are less than 2 mm and for angular variables < 8°. The average MAD and REM for length measurements are 0.94 mm and 5.64%, and for angular measurements are 2.27° and 3.78%, respectively.

CONCLUSIONS

The soft tissue results measured by CBCT show relatively good reliability and can be used for 3D measurement of soft tissue in the nasolabial region clinically.

Ultra-low-dose cone-beam CT compared to standard dose in the assessment for acute fractures

PURPOSE

Multi-detector computed tomography (MDCT) is superior in fracture detection than conventional radiography; however, dose is increased. Cone-beam computed tomography (CBCT) offers higher spatial resolution and lower dose than MDCT. Manufacturers offer an ultra-low-dose algorithm. This study compares the diagnostic accuracy of the ultra-low-dose CBCT (ULDCBCT) with that of the standard-dose CBCT (SDCBCT).

MATERIALS AND METHODS

In total, 64 patients were scanned with both the SDCBCT and the ULDCBCT protocols. Both studies were reported by two consultant radiologists with fellowship training in emergency radiology separated in time. The reporter recorded a diagnosis of fracture or normal and diagnostic confidence using a 5-point Likert scale. The gold standard was taken as the SDCBCT. Reporters were blinded to the indication and the SDCBCT report. Cases of discrepancy were resolved by consensus.

RESULTS

There were 34 fractures and 30 cases had no fracture. Several fractures were missed using the UDCBCT, and there were also several cases of overdiagnosis. ULD was inferior to SD for fracture diagnosis (p < 0.00001). The diagnostic accuracy of ULDCBCT was 82.8% (75.1-88.9 CI). The diagnostic accuracy of plain radiograph was 64% (55.1-75.7% CI). Diagnostic confidence was reduced; the mean confidence for SDCBCT was 4.68 vs 4.12 for ULDCBCT (p < 0.001). The Kappa for interobserver agreement was 0.6.

CONCLUSION

ULDCBCT is inferior to SDCBCT in fracture detection and confidence is reduced. For diagnostic studies, the standard dose should be used.

Portal Vein Embolization Using N-Butyl Cyanoacrylate-Glue: What Impact Does a Central Vascular Plug Have?

Purpose

To examine if the addition of a central vascular plug (CVP) to portal vein embolization (PVE) with N-butyl cyanoacrylate-glue (NBCA) increases future liver remnant (FLR) growth.

Material and Methods

This is a single-center retrospective study of 115 consecutive patients with colorectal liver metastases undergoing PVE in 2013–2019. All patients were embolized with NBCA as the main embolic agent. In 2017–2019 NBCA was combined with a CVP in the central part of the right portal vein. Growth of the FLR and standardized FLR (sFLR) including degree of hypertrophy (DH) and kinetic growth rate (KGR) were analyzed, as well as procedure data such as use of cone-beam CT (CBCT), dose area product (DAP), fluoroscopy time and contrast dose.

Results

A total of 40 patients (35%) underwent PVE with a combination of CVP and NBCA. The DH was higher in these patients after 4 weeks, mean 13.6% (SD 7.8) vs. 10.5% (SD 6.4; p = 0.022), verified in multivariate analysis (coefficient 4.1, p = 0.015). A CVP did not significantly increase the resection rate (90% vs 82%, p = 0.4). Cone beam CT was used in 65 patients (57%). Use of CBCT did not affect FLR growth, and fluoroscopy time and contrast doses were not different in patients having a CBCT or not. Slightly lower DAP (median 3375 vs. 4499 cGy*cm²; p = 0.09) was seen in procedures where CBCT was used.

Conclusion

A CVP in addition to NBCA embolization was associated with increased growth of the FLR compared to NBCA alone.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-021-03014-w.

CBCT-based synthetic CT generation using generative adversarial networks with disentangled representation

Background

Cone-beam computed tomography (CBCT) plays a key role in image-guided radiotherapy (IGRT), however its poor image quality limited its clinical application. In this study, we developed a deep-learning based approach to translate CBCT image to synthetic CT (sCT) image that preserves both CT image quality and CBCT anatomical structures.

Methods

A novel synthetic CT generative adversarial network (sCTGAN) was proposed for CBCT-to-CT translation via disentangled representation. The approach of disentangled representation was employed to extract the anatomical information shared by CBCT and CT image domains. Both on-board CBCT and planning CT of 40 patients were used for network learning and those of another 12 patients were used for testing. Accuracy of our network was quantitatively evaluated using a series of statistical metrics, including the peak signal-to-noise ratio (PSNR), mean structural similarity index (SSIM), mean absolute error (MAE), and root-mean-square error (RMSE). Effectiveness of our network was compared against three state-of-the-art CycleGAN-based methods.

Results

The PSNR, SSIM, MAE, and RMSE between sCT generated by sCTGAN and deformed planning CT (dpCT) were 34.12 dB, 0.86, 32.70 HU, and 60.53 HU, while the corresponding values between original CBCT and dpCT were 28.67 dB, 0.64, 70.56 HU, and 112.13 HU. The RMSE (60.53±14.38 HU) of sCT generated by sCTGAN was less than that of sCT generated by all the three comparing methods (72.40±16.03 HU by CycleGAN, 71.60±15.09 HU by CycleGAN-Unet512, 64.93±14.33 HU by CycleGAN-AG).

Conclusions

The sCT generated by our sCTGAN network was closer to the ground truth (dpCT), in comparison to all the three comparing CycleGAN-based methods. It provides an effective way to generate high-quality sCT which has a wide application in IGRT and adaptive radiotherapy.

Intraoperative 3D imaging with cone-beam computed tomography leads to revision of pedicle screws in dorsal instrumentation: a retrospective analysis

Background

Correct positioning of pedicle screws can be challenging. Intraoperative imaging may be helpful. The purpose of this study was to evaluate the use of intraoperative 3D imaging with a cone-beam CT. The hypotheses were that intraoperative 3D imaging (1) will lead to an intraoperative revision of pedicle screws and (2) may diminish the rate of perforated screws on postoperative imaging.

Methods

Totally, 351 patients (age 60.9 ± 20.3 a (15–96); m/f 203/148) underwent dorsal instrumentation with intraoperative 3D imaging with 2215 pedicle screws at a trauma center level one. This study first evaluates intraoperative imaging. After this, 501 screws in 73 patients (age 62.5 ± 19.7 a; m/f 47/26) of this collective were included in the study group (SG) and their postoperative computed tomography was evaluated with regard to screw position. Then, 500 screws in 82 patients (age 64.8 ± 14.4 a; m/f 51/31) as control group (CG), who received the screws with conventional 2D fluoroscopy but without 3D imaging, were evaluated with regard to screw position.

Results

During the placement of the 2215 pedicle screws, 158 (7.0%) intraoperative revisions occurred as a result of 3D imaging. Postoperative computed tomography of the SG showed 445 (88.8%) screws without relevant perforation (type A + B), of which 410 (81.8%) could be classified as type A and 35 (7.0%) could be classified as type B. Fifty-six (11.2%) screws in SG showed relevant perforation (type C–E). In contrast, 384 (76.8%) screws in the CG were without relevant perforation (type A + B), of which 282 (56.4%) could be classified as type A and 102 (20.4%) as type B. One hundred and sixteen (23.2%) screws in the CG showed relevant perforation (type C–E).

Conclusion

This study shows that correct placement of pedicle screws in spine surgery with conventional 2D fluoroscopy is challenging. Misplacement of screws cannot always be prevented. Intraoperative 3D imaging with a CBCT can be helpful to detect and revise misplaced pedicle screws intraoperatively. The use of intraoperative 3D imaging will probably minimize the number of revision procedures due to perforating pedicle screws.

The surgical-orthodontic management of combined impacted maxillary second and third molars

BACKGROUND

A correlation between impacted maxillary third molars on the eruption potential of the maxillary second molar has been identified. There is little published evidence available in the literature regarding a treatment modality for this presentation. AIMS  : The aim of this case series is to propose a joint surgical and orthodontic approach for the management of such cases. METHOD  : A retrospective search of all patients treated for impacted second and third maxillary molars from 2014 to 2020 revealed 24 cases. Surgical planning was facilitated with the use of a CBCT to help orientate the teeth in 3-D and assess any associated pathology to nearby structures. Twenty-three cases were treated via surgical removal of the impacted third molar and subsequently monitored for spontaneous maxillary second molar eruption.

CONCLUSION

 All treated cases showed complete or partial spontaneous eruption followed by orthodontic repositioning if required.

Comparison of diagnosis of cracked tooth using contrast-enhanced CBCT and micro-CT

OBJECTIVES

To evaluate the diagnostic accuracy using sodium iodide (NaI) and dimethyl sulfoxide (DMSO) as contrast agent in cone beam computed tomography (CBCT) scanning, and compare this with micro-CT.

METHODS

18 teeth were cracked artificially by soaking them cyclically in liquid nitrogen and hot water. After pre-treatment with artificial saliva, the teeth were scanned in four modes: CBCT routine scanning without contrast agent (RS); CBCT with meglumine diatrizoate (MD) as contrast agent (ES1); CBCT with NaI + DMSO as contrast agent (ES2); and micro-CT (mCT). The number of crack lines was evaluated in all four modes. Depth of crack lines and number of cracks presented from the occlusal surface to the pulp cavity (Np) in ES2 and micro-CT images were evaluated.

RESULTS

There were 63 crack lines in all 18 teeth. 45 crack lines were visible on ES2 images as against four on the RS and ES1 images (p<0.05) and 37 on micro-CT images (p>0.05). Further, 34 crack lines could be observed on both ES2 and micro-CT images, and the average depth presented on ES2 images was 4.56 ± 0.88 mm and 3.89 ± 1.08 mm on micro-CT images (p<0.05). More crack lines could be detected from the occlusal surface to the pulp cavity on ES2 images than on micro-CT images (22 vs 11).

CONCLUSION

CBCT with NaI +DMSO as the contrast agent was equivalent to micro-CT for number of crack lines and better for depth of crack lines. NaI + DMSO could be a potential CBCT contrast agent to improve diagnostic accuracy for cracked tooth.

Clinical efficiency of operating room-based sliding gantry CT as compared to mobile cone-beam CT-based navigated pedicle screw placement in 853 patients and 6733 screws

PURPOSE

Multiple solutions for navigation-guided pedicle screw placement are available. However, the efficiency with regard to clinical and resource implications has not yet been analyzed. The present study's aim was to analyze whether an operating room sliding gantry CT (ORCT)-based approach for spinal instrumentation is more efficient than a mobile cone-beam CT (CBCT)-based approach.

METHODS

This cohort study included a random sample of 853 patients who underwent spinal instrumentation using ORCT-based or CBCT-based pedicle screw placement due to tumor, degenerative, trauma, infection, or deformity disorders between November 2015 and January 2020.

RESULTS

More screws had to be revised intraoperatively in the CBCT group due to insufficient placement (ORCT: 98, 2.8% vs. CBCT: 128, 4.0%; p = 0.0081). The mean time of patients inside the OR (Interval 5 Entry-Exit) was significantly shorter for the ORCT group (ORCT: mean, [95% CI] 256.0, [247.8, 264.3] min, CBCT: 283.0, [274.4, 291.5] min; p < 0.0001) based on shorter times for Interval 2 Positioning-Incision (ORCT: 18.8, [18.1, 19.9] min, CBCT: 33.6, [32.2, 35.5] min; p < 0.0001) and Interval 4 Suture-Exit (ORCT: 24.3, [23.6, 26.1] min, CBCT: 29.3, [27.5, 30.7] min; p < 0.0001).

CONCLUSIONS

The choice of imaging technology for navigated pedicle screw placement has significant impact on standard spine procedures even in a high-volume spine center with daily routine in such devices. Particularly with regard to the duration of surgeries, the shorter time needed for preparation and de-positioning in the ORCT group made the main difference, while the accuracy was even higher for the ORCT.

Does Intraprocedural CT Improve the Success Rate of Adrenal Venous Sampling? A Systematic Review and Meta-Analysis of Data from 809 Patients

PURPOSE

To perform a systematic review and meta-analysis to quantify the technical success rate of adrenal venous sampling (AVS) with and without intraprocedural computed tomography (CT).

METHODS

A systematic search of the Medline, Scopus, EMBASE, and Web of Science databases for comparative studies using intraprocedural CT was undertaken. More than 1,000 records were screened using titles and abstracts. Full texts of 121 studies were reviewed and 14 eligible studies were identified. Nine studies had adequate comparative data and were included in the meta-analysis.

RESULTS

A research synthesis was performed and data from 809 patients were pooled in multiple random effect models. Overall success rate of AVS without and with intraprocedural CT was 72.7% (59.3-83.0%) and 92.5% (86.6-95.9), respectively. The addition of intraprocedural CT increased the technical success rate by 19.8% (P < 0.001), with an odds ratio (OR) of 5.5 (3.3-9.2; P < 0.01). In meta-regression, odds of success with intraprocedural CT was associated with younger age (beta: 0.16 ± 0.05; P:0.001), higher body mass index (BMI; beta:0.08 ± 0.03; P:0.002), and higher selectivity index (defined as the ratio of cortisol in the adrenal vein to that in the inferior vena cava; beta:0.35 ± 0.08, P < 0.001). We found a linear inverse association between operator's success without CT and improved success with intraprocedural CT (R²: 0.86).

CONCLUSIONS

Intraprocedural CT is not required for every case, but can be performed in difficult cases or when operators' success is limited. The benefit was more pronounced in younger patients with higher BMI, female gender, and with higher selectivity.

LEVEL OF EVIDENCE

III Systematic review and meta-analysis of non-randomized clinical trials.

Mesorectal shape variation in rectal cancer radiotherapy in prone position using a belly board

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Mesorectal shape variation is diverse and largest in the upper-anterior region.

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Derived planning target volume margins for the upper-anterior region were larger in female patients.

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Planning target volume margins are comparable for radiotherapy and chemoradiotherapy groups.

Background and purpose

In rectal cancer patients, radiotherapy in prone position using a belly board can reduce the dose to organs at risk. For this patient group we investigated inter-fraction shape variation of the mesorectal part of the clinical target volume (CTV) and determined planning target volume (PTV) margins.

Materials and methods

Patients with rectal cancer receiving neoadjuvant (chemo)radiotherapy were eligible. For each patient a planning computed tomography (pCT) and five cone-beam CT (CBCT) scans were acquired in prone position using a belly board. The mesorectal CTV was delineated on all scans. Mesorectal shape variation was quantified relative to the pCT. PTV margins were derived locally and averaged for separate subregions of the mesorectal CTV. For each patient a total PTV was constructed using our clinical margins for mesorectal and lymph node CTVs. An artificial dose distribution conforming to this PTV was used to calculate the coverage for the mesorectal CTV using the CBCT delineations.

Results

In 19 rectal cancer patients the derived PTV margins were smallest in the upper-lateral region (6 mm) and largest in the upper-anterior region (16 mm). PTV margins for the upper-anterior region were larger for female patients (19 mm) compared to male patients (14 mm). Clinical margins for the total PTV were sufficient for a coverage of at least 97% of the mesorectal CTV for all patients.

Conclusions

Mesorectal shape variation is heterogeneous and largest in the upper-anterior region, in rectal cancer patients irradiated in prone position and using a belly board.

Does Alt-RAMEC protocol and facemask treatment affect dentoalveolar structures?

OBJECTIVES

To evaluate dentoalveolar changes immediately after the alternate rapid maxillary expansion and constriction (Alt-RAMEC) protocol and facemask (FM) treatment using cone-beam computed tomography images.

MATERIALS AND METHODS

Cone-beam computed tomography images of 20 patients (mean age = 9.64 ± 1.3 years) who received the Alt-RAMEC protocol before FM treatment were retrieved in this retrospective study. Dental and alveolar inclinations, buccal and palatal alveolar bone thickness, and buccal and palatal alveolar bone height changes were measured before treatment (T0), after the Alt-RAMEC protocol (T1), and after FM treatment (T2). Measurements for right and left molars were performed separately. The Shapiro-Wilks test was used to assess the conformity of the parameters to the normal distribution. The paired t-test and repeated measures analysis of variance were used for normally distributed data. The Wilcoxon signed-rank test and Friedman test were used for non-normally distributed data. The Bonferroni correction was used to reduce the chances of obtaining false-positive results. Statistical significance was set at P < .05.

RESULTS

Buccal alveolar bone thickness and alveolar bone inclinations decreased significantly from T1 to T0 and showed no significant change from T2 to T1. The total reduction T2-T0 was statistically significant. The change in palatal alveolar bone thickness was not significant T1-T0 but increased significantly for T2-T1 and T2-T0. Buccal alveolar bone height, palatal alveolar bone height, and molar inclinations increased significantly T1-T0, but there was no significant change T2-T1. The total reduction at T2-T0 was statistically significant.

CONCLUSIONS

The results of this study revealed that the effects of the Alt-RAMEC protocol on dentoalveolar tissues were similar to the changes reported in the literature after rapid palatal expansion.

Evaluation of Software-Based Metal Artifact Reduction in Intraoperative 3D Imaging of the Spine Using a Mobile Cone Beam CT

The aim of our study was to evaluate whether software-based artifact reduction can achieve an improved image quality, using intraoperative 3D imaging in spinal surgery. A total of 49 intraoperative 3D image datasets of patients, who underwent surgery with pedicle screw placement, were retrospectively evaluated. The visibility of anatomical structures and the diameter of the pedicle screws were examined, with and without the application of the artifact reduction software. All software prototypes can improve the visibility of anatomical structures (P < 0.01), except MAR (metal artifact reduction) combined with IRIS (iterative reconstruction in image space) (P = 0.04). The algorithms MAR and MAR-2 can reduce the blooming artifacts significantly (P < 0.01), but SL (Shepp & Logan) cannot (P = 0.08-0.988). In summary, software-based artifact reduction for intraoperative 3D datasets can improve the current image quality. Additional information regarding the implant placement and the fracture reduction is therefore generated for the surgeon.

CBCT analysis of the tissue thickness at immediate implant placement with contour augmentation in the maxillary anterior zone: a 1-year prospective clinical study

Background

Immediate implant placement with simultaneous contour augmentation such as guided bone regeneration (GBR) or connective tissue grafting (CTG) has been widely performed. However, few prospective studies have evaluated both peri-implant bone and soft tissue changes between the preoperative and postoperative periods. The purpose of this study is to quantify the horizontal dimensional changes of the facial bone and soft tissue following immediate implant placement with contour augmentation.

Material and methods

Twenty patients who underwent immediate implant placement in the anterior maxilla received GBR and CTG (test group) or GBR only (control group). Cone-beam computed tomography (CBCT) scans were taken preoperatively and 1 year after the definitive prosthesis connection, and then, they were superimposed. On the CBCT images of the two stages, the horizontal distance from the implant platform to the facial bone surface (BW) and the horizontal soft tissue width (GW) were measured at the implant platform level and 2 mm apical to the implant platform level. The sum of BW and GW (=TW) was used to assess the facial mucosal contour.

Results

BW decreased significantly from preoperative to 1 year after prosthesis connection with a mean decrease of 0.47 mm (P =0.021) in the control group and a mean decrease of 0.50 mm (P = 0.019) in the test group at the implant platform level. GW increased significantly with a mean increase of 1.37 mm (P =0.005) in the test group at the implant platform level. TW decreased significantly with a mean decrease of 0.46 mm in the control group (P =0.049) but increased significantly with a mean increase of 0.87 mm in the test group (P =0.005) at the implant platform level.

Conclusions

Immediate implant placement with CTG showed a soft tissue gain of 1.37 mm compensated for bone resorption, thus still preserving the preoperative mucosal contour. CTG should be performed with immediate implant placement in cases where preoperative mucosal contours need to be maintained.

Evaluation of the accuracy values of cone-beam CT regarding apical periodontitis: a systematic review and meta-analysis

Specialists need to know how accurate and effective each radiographic procedure is, and which ones can provide better images for bone resorption around the apical periodontitis. Therefore, the researcher decided to conduct the present study with the aim of evaluate the accuracy values of cone-beam CT regarding apical periodontitis. The PubMed, Embase, ISI, Scopus, and Medicine have been used to search articles over the last 15 years between 2005 and December 2020. Meta-analysis data with 95% confidence interval (CI), Random effect model, and restricted maximum-likelihood methods were calculated. Random effects were used to deal with potential heterogeneity and I² showed heterogeneity. I² values above 50% signified moderate-to-high heterogeneity. The meta-analysis has been evaluated with the statistical software Stata/MP v.16 (The fastest version of Stata). One hundred and fifty-eight studies were selected to review the abstracts, six papers met these crucial criteria to do a systematic review and meta-analysis. Sensitivity and specificity of digital periapical radiography was 50% (ES 0.50; 95% CI 0.05, 0.95) and 83% (ES 0.83; 95% CI 0.52, 1.15), respectively. Sensitivity and specificity of cone-beam computed tomographic was 95% (ES 0.95; 95% CI 0.80, 1.00) and 90% (ES 0.90; 95% CI 0.78, 1.03), respectively. In conclusion, CBCT imaging reports values with excellent accuracy vs digital periapical radiography.

A compact and mobile hybrid C-arm scanner for simultaneous nuclear and fluoroscopic image guidance

Purpose

This study evaluates the performance of a mobile and compact hybrid C-arm scanner (referred to as IXSI) that is capable of simultaneous acquisition of 2D fluoroscopic and nuclear projections and 3D image reconstruction in the intervention room.

Results

The impact of slightly misaligning the IXSI modalities (in an off-focus geometry) was investigated for the reduction of the fluoroscopic and nuclear interference. The 2D and 3D nuclear image quality of IXSI was compared with a clinical SPECT/CT scanner by determining the spatial resolution and sensitivity of point sources and by performing a quantitative analysis of the reconstructed NEMA image quality phantom. The 2D and 3D fluoroscopic image of IXSI was compared with a clinical CBCT scanner by visualizing the Fluorad A+D image quality phantom and by visualizing a reconstructed liver nodule phantom. Finally, the feasibility of dynamic simultaneous nuclear and fluoroscopic imaging was demonstrated by injecting an anthropomorphic phantom with a mixture of iodinated contrast and ^99mTc.

Conclusion

Due to the divergent innovative hybrid design of IXSI, concessions were made to the nuclear and fluoroscopic image qualities. Nevertheless, IXSI realizes unique image guidance that may be beneficial for several types of procedures.

Key Points

• IXSI can perform time-resolved planar (2D) simultaneous fluoroscopic and nuclear imaging.

• IXSI can perform SPECT/CBCT imaging (3D) inside the intervention room.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08023-4.

Simulation of superselective catheterization for cerebrovascular lesions using a virtual injection software

Background

This report addresses the feasibility of virtual injection software based on contrast-enhanced cone-beam CTs (CBCTs) in the context of cerebrovascular lesion embolization. Intracranial arteriovenous malformation (AVM), dural arteriovenous fistula (AVF) and mycotic aneurysm embolization cases with CBCTs performed between 2013 and 2020 were retrospectively reviewed. Cerebrovascular lesions were reviewed by 2 neurointerventionalists using a dedicated virtual injection software (EmboASSIST, GE Healthcare; Chicago, IL). Points of Interest (POIs) surrounding the vascular lesions were first identified. The software then automatically displayed POI-associated vascular traces from vessel roots to selected POIs. Vascular segments and reason for POI identification were recorded. Using 2D multiplanar reconstructions from CBCTs, the accuracy of vascular traces was assessed. Clinical utility metrics were recorded on a 3-point Likert scale from 1 (no benefit) to 3 (very beneficial).

Results

Nine cases (7 AVM, 1 AVF, 1 mycotic aneurysm) were reviewed, with 26 POIs selected. Three POIs were in 2nd order segments, 8 POIs in 3rd order segments and 15 POIs in 4th order segments of their respective arteries. The reviewers rated all 26 POI traces – involving a total of 90 vascular segments – as accurate. The average utility score across the 8 questions were 2.7 and 2.8 respectively from each reviewer, acknowledging the software’s potential benefit in cerebrovascular embolization procedural planning.

Conclusion

The operators considered CBCT-based virtual injection software clinically useful and accurate in guiding and planning cerebrovascular lesion embolization in this retrospective review. Future prospective studies in larger cohorts are warranted for validation of this modality.