Image-guided Method Research Articles

Application of low-dose CT in image-guided radiotherapy based on CT-linac

BackgroundImage-guided radiation therapy (IGRT) involves online medical imaging systems. CT-guided imaging systems not only have high image quality but also allow for direct dose calculation for radiation treatment planning, making it an ideal image guidance method. However, the imaging dose from CT images may pose additional risks to patients. Therefore, the aim of this study was to evaluate the substitutability of using low-dose CT images for IGRT. Materials and methodsThe CIRS-062 phantom, Catphan 604 phantom, CT dose index phantom were used to obtain the conversion curves of the CT values to the relative electron density (RED), image quality, and imaging dose of the low-dose CT, respectively. Catphan 604 phantom and clinical cases were used to analyze the feasibility of low-dose CT for dose calculation. ResultsNo significant differences were observed in the conversion curves of CT values to RED between low-dose and standard-dose CT scans. In terms of image quality, the geometric distortion of low-dose CT was 0.1 mm, which was the same as that of standard-dose CT. The spatial resolution of the images was 0.42–0.45 lp/mm, which was slightly better than that of standard-dose CT (0.40–0.44 lp/mm). The image uniformity was 98.4%–99.0%, slightly worse than that of standard-dose CT (99.4%–99.5%), but still met the clinical requirements. The imaging dose was 2.96–4.62 mGy, significantly lower than that of standard-dose CT (9.71–26.68 mGy), especially for head CT protocol. In terms of dose calculation, the γ passing rates were not lower than 98% for either the Catphan 604 phantom or the clinical cases. ConclusionLow-dose CT can significantly reduce the imaging dose without a significant loss of image quality and can be directly used for dose calculation in radiation treatment planning, providing a safer and more effective image guidance method for IGRT.

Application of surface-guided radiation therapy in prostate cancer: comparative analysis of differences with skin marking-guided patient setup.

Surface-guided radiation therapy is an image-guided method using optical surface imaging that has recently been adopted for patient setup and motion monitoring during treatment. We aimed to determine whether the surface guide setup is accurate and efficient compared to the skin-marking guide in prostate cancer treatment. The skin-marking setup was performed, and vertical, longitudinal, and lateral couch values (labeled as "M") were recorded. Subsequently, the surface-guided setup was conducted, and couch values (labeled as "S") were recorded. After performing cone-beam computed tomography (CBCT), the final couch values was recorded (labeled as "C"), and the shift value was calculated (labeled as "Gap (M-S)," "Gap (M-C)," "Gap (S-C)") and then compared. Additionally, the setup times for the skin marking and surface guides were also compared. One hundred and twenty-five patients were analyzed, totaling 2,735 treatment fractions. Gap (M-S) showed minimal differences in the vertical, longitudinal, and lateral averages (-0.03 cm, 0.07 cm, and 0.06 cm, respectively). Gap (M-C) and Gap (S-C) exhibited a mean difference of 0.04 cm (p = 0.03) in the vertical direction, a mean difference of 0.35 cm (p = 0.52) in the longitudinal direction, and a mean difference of 0.11 cm (p = 0.91) in the lateral direction. There was no correlation between shift values and patient characteristics. The average setup time of the skin-marking guide was 6.72 minutes, and 7.53 minutes for the surface guide. There was no statistically significant difference between the surface and skin-marking guides regarding final CBCT shift values and no correlation between translational shift values and patient characteristics. We also observed minimal difference in setup time between the two methods. Therefore, the surface guide can be considered an accurate and time-efficient alternative to skin-marking guides.

Application of an effective marker-less augmented reality image guidance method in dental implant surgery.

The existing augmented reality (AR) dental implant surgery navigation system usually uses markers to complete image guidance. However, markers often affect dentists' operations and make patients uncomfortable. To solve the problems caused by markers, this paper proposes an effective marker-less image guidance method. After initialisation is completed by contour matching, the corresponding relationship is obtained by matching the feature points between the current frame and the preloaded initial frame. The camera pose is estimated by solving the Perspective-n-Point problem. The registration error of AR images is 0.731±0.144mm. The planting errors are 1.174±0.241mm at the neck, 1.433±0.389mm at the apex and 5.566±2.102° for the angle. The maximum error and standard deviation meet the clinical requirements. We demonstrate that the proposed method can accurately guide dentists to perform dental implant surgery.

Imaging Recommendations for Image-Guided Biopsy in Oncology

AbstractThe percutaneous needle biopsy (PNB) is the initial step for obtaining the diagnosis and it helps in treatment. It aids in primary diagnosis, tumor staging, or ruling out infective etiology. It is a safe and successful minimally invasive method compared to open biopsies. PNB is defined as the placement and insertion of a needle into a suspected lesion or organ with the intent of retrieving tissue or cells for diagnosis. It can fine needle aspiration cytology or core needle biopsy. The patient needs to be counseled regarding the procedure and detailed history, including anticoagulant history needs to be taken. The SIR consensus guidelines have divided biopsies into low-risk procedures with a bleeding risk of < 1.5% and high-risk procedures > 1.5%. There are advancements in needle design (e.g., echogenic tip while performing ultrasound-guided needle biopsy) and image-guidance technology (ultrasound quality, multi-slice CT scan) that improved these procedures safety and efficacy. There are different types of needles available such as coaxial, aspiration needles, Murphy's bone biopsy needle, which depends on the tissue which needs to be sampled or the organ to be biopsied. Various different types of biopsy guns, such as semi-automatic, automatic, or manual are available. The newer technology such as fusion and navigation biopsies helps in better characterizing and localization of the lesion, improving the yield of the biopsy. Open and excisional biopsies have a higher mortality and morbidity rate than percutaneous biopsies, they are reserved for cases where the image-guided method has failed to provide the diagnostic yield. Sample collection must be done under a sterile container in formaline or microbiological examination. Regular analysis and rad-path correlation are key to success and improving diagnostic yield. This abstract provides an overview of the existing biopsy literature.

Development and validation of a scatter-corrected CBCT image-guided method for cervical cancer brachytherapy.

Multiple patient transfers have a nonnegligible impact on the accuracy of dose delivery for cervical cancer brachytherapy. We consider using on-site cone-beam CT (CBCT) to resolve this problem. However, CBCT clinical applications are limited due to inadequate image quality. This paper implements a scatter correction method using planning CT (pCT) prior to obtaining high-quality CBCT images and evaluates the dose calculation accuracy of CBCT-guided brachytherapy for cervical cancer. The CBCT of a self-developed female pelvis phantom and five patients was first corrected using empirical uniform scatter correction in the projection domain and further corrected in the image domain. In both phantom and patient studies, the CBCT image quality before and after scatter correction was evaluated with registered pCT (rCT). Model-based dose calculation was performed using the commercial package Acuros®BV. The dose distributions of rCT-based plans and corrected CBCT-based plans in the phantom and patients were compared using 3D local gamma analysis. A statistical analysis of the differences in dosimetric parameters of five patients was also performed. In both phantom and patient studies, the HU error of selected ROIs was reduced to less than 15 HU. Using the dose distribution of the rCT-based plan as the baseline, the γ pass rate (2%, 2mm) of the corrected CBCT-based plan in phantom and patients all exceeded 98% and 93%, respectively, with the threshold dose set to 3, 6, 9, and 12 Gy. The average percentage deviation (APD) of D90 of HRCTV and D2cc of OARs was less than 1% between rCT-based and corrected CBCT-based plans. Scatter correction using a pCT prior can effectively improve the CBCT image quality and CBCT-based cervical brachytherapy dose calculation accuracy, indicating promising prospects in both simplified brachytherapy processes and accurate brachytherapy dose delivery.

Current diagnosis and image-guided reduction for intussusception in children.

Intussusception involves an invagination of the proximal bowel into the distal bowel, with ileocolic intussusception being the most common type. However, a diagnostic delay can lead to intestinal ischemia, bowel infarction, or even death; therefore, its early diagnosis and management are important. The primary role of abdominal radiography is to detect pneumoperitoneum or high-grade bowel obstruction in cases of suspected intussusception, and ultrasonography is the modality of choice for its diagnosis. Nonoperative enema reduction, the treatment of choice for childhood intussusception in cases without signs of perforation or peritonitis, can be safely performed with a success rate of 82%. Enema reduction can be performed in various ways according to image guidance method (fluoroscopy or ultrasonography) and reduction medium (liquid or air). Successful enema reduction is less likely to be achieved in children with a longer symptom duration, younger age, lethargy, fever, bloody diarrhea, unfavorable radiologic findings (small bowel obstruction, trapped fluid, ascites, absence of flow in the intussusception, intussusception in the left-sided colon), and pathological lead points. This review highlights the current concepts of intussusception diagnosis, nonsurgical enema reduction, success rates, predictors of failed enema reduction, complications, and recurrence to guide general pediatricians in the management of childhood intussusception.

Abstract 2469: Image-guided focused ultrasound-mediated drug delivery for improved cancer treatment

Abstract Introduction: The first option for cancer treatment is often chemotherapy. However, studies have shown that only 1% of the injected dose reaches the target cancer as the tumor microenvironment presents a physical barrier for optimal drug delivery. Focused ultrasound (FUS) in combination with microbubble (MB) contrast agents is an emerging therapy to improve drug delivery by temporarily increasing microvascular permeability. This research details the development and testing of a novel ultrasound (US) image-guided FUS system and method for enhancing drug delivery to tumor tissue and volume space with comparison to a 2-dimensional (2-D) US therapeutic technology. Methods: Real-time US therapy was implemented on a programmable US system (Vantage 256, Verasonics Inc) equipped with a dual US transducer configuration for interleaved anatomical imaging and volumetric treatment delivery (HIFU-Plex, Sonic Concepts Inc). Both US imaging and therapeutic transducers are co-registered 128 element arrays with center frequencies of 3.5 and 2.0 MHz, respectively. The latter is a concentric array that enables beam steering in 3-dimensional (3-D) space. US treatment was performed at a peak negative pressure of 0.7 MPa (mechanical index, MI of 0.45), pulse repetition frequency of 10 Hz, and duty cycle of 10%. BALB/c mice (N = 22, Charles River Laboratory) were implanted with 2.0 × 105 breast cancer cells (4T1, ATCC). Once tumors reached 0.6 cm in size, mice were randomly divided into a 3-D or 2-D US therapy group or sham control. US therapy was performed following an intravascular injection of microbubbles (Definity, Lantheus Medical Imaging) and IR-780 dye. Note microbubbles function as a therapeutic mediator whereas the fluorescent dye represents a surrogate small molecule drug. Live animal fluorescent imaging was performed at baseline before US therapy (0 h) and again at 1, 24, and 48 h. Following the 48 h timepoint, animals were euthanized and tumors surgically excised for ex vivo analysis. Results: 3-D US-mediated therapy improved molecular delivery to tumor tissue by 150 and 180% at 24 and 48 h, respectively, when compared to our previously established 2-D US therapeutic approach (p = 0.22) or sham therapy (p = 0.07). A similar trend was observed during ex vivo imaging of excised tumor samples treated with 3-D US therapy as compared to the 2-D US therapeutic approach (p = 0.41) or sham therapy (p = 0.04). Dye extraction further confirmed these observations (p > 0.12). Conclusions: 3-D US therapy improved molecular delivery to the tumor volume compared to our previously established 2-D US-based method as confirmed by a series of optical imaging studies. Citation Format: Ryan Margolis, Junjie Li, Lokesh Basavarajappa, Kenneth Hoyt. Image-guided focused ultrasound-mediated drug delivery for improved cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2469.

Outcomes of Cardiac Resynchronization Therapy with Image-Guided Left Ventricular Lead Placement at the Site of Latest Mechanical Activation: A Systematic Review and Meta-Analysis.

Aim To assess evidence for an image-guided approach for cardiac resynchronization therapy (CRT) that targets left ventricular (LV) lead placement at the segment of latest mechanical activation. Methods A systematic review of EMBASE and PubMed was performed for randomized controlled trials (RCTs) and prospective observational studies from October 2008 through October 2020 that compared an image-guided CRT approach with a non-image-guided approach for LV lead placement. Meta-analyses were performed to assess the association between the image-guided approach and NYHA class improvement or changes in end-systolic volume (LVESV), end-diastolic volume (LVEDV), and ejection fraction (LVEF). Results From 5897 citations, 5 RCTs including 818 patients (426 image-guided and 392 non-image-guided) were identified. The mean age ranged from 66 to 71 years, 76% were male, and 53% had ischemic cardiomyopathy. Speckle tracking echocardiography was the primary image-guided method in all studies. LV lead placement within the segment of the latest mechanical activation (concordant) was achieved in the image-guided arm in 45% of the evaluable patients. There was a statistically significant improvement in the NYHA class at 6 months (odds ratio 1.66; 95% confidence interval (CI) [1.02, 2.69]) with the image-guided approach, but no statistically significant change in LVESV (MD −7.1%; 95% CI [−16.0, 1.8]), LVEDV (MD −5.2%; 95% CI [−15.8, 5.4]), or LVEF (MD 0.68; 95% CI [−4.36, 5.73]) versus the non-image-guided approach. Conclusion The image-guided CRT approach was associated with improvement in the NYHA class but not echocardiographic measures, possibly due to the small sample size and a low rate of concordant LV lead placement despite using the image-guided approach. Therefore, our meta-analysis was not able to identify consistent improvement in CRT outcomes with an image-guided approach.

Accuracy of Toric Intraocular Lens Axis Alignment Using Manual Slit Lamp Method and CALLISTO Eye Image-Guided System

Aims: Image-guided systems are the gold standard for determining toric intraocular lens (IOL) axis alignment. However, their high cost prevents widespread use of these systems. As an alternative, a simpler and affordable method could be performed manually using a slit-lamp biomicroscope. This study aims to compare the accuracy of manual toric IOL axis marking using a slit-lamp compared to the CALLISTO eye image-guided system.
 Study Design: Prospective comparative
 Methods: In this prospective study, toric IOL axis alignment of 42 eyes with cataract and coexisting corneal astigmatism were evaluated using manual slitlamp method and CALLISTO eye image-guided method. Preoperative and postoperative uncorrected visual acuity, best corrected visual acuity, amount of spherical and astigmatic refractive errors, and postoperative IOL axis alignment were evaluated. Intraclass correlation of the manual method was calculated and the difference of IOL axis alignment to the image-guided method was compared.
 Results: Toric IOL implantation reduced the amount of astigmatic refractive error from -1.63 ± 0.65 D to -0.50 ± 0.19 D in the image-guided group and from -1.93 ± -0.90 D to -0.87 ± 0.26 D in the manual slitlamp group. As many as 90.5% of eyes in the image-guided group and 81.0% of eyes in the manual slitlamp group reached the target induced astigmatism (p=0.38). Manual axis marking showed intraclass correlation of 99.3%. However, when the manual method was compared to the image-guided method a mean difference in axis alignment of 10.98o (95% confidence interval: 9.32o - 12.63o) was observed.
 Conclusions: Alignment of toric IOL axis using the manual method demonstrated a consistent result; yet producing a considerable difference to the result of the image-guided method.

Effectiveness of percutaneous vacuum-assisted excision (VAE) of breast lesions of uncertain malignant potential (B3 lesions) as an alternative to open surgical biopsy.

Traditionally B3 breast lesions are treated surgically, but overtreatment is a concern, as the majority have a final benign diagnosis. A national screening program introduced vacuum-assisted excision (VAE) for managing B3 lesions in late 2016. This retrospective study aimed to assess the outcomes associated with this approach. All B3 lesions diagnosed between 01/2017 and 12/2019 were identified at two centres. Information was obtained on the initial biopsy and final histology, and method of VAE image guidance, needle size and number of cores. Lesions were excluded if there was cancer elsewhere in the breast at the time of diagnosis; the lesion was not suitable for VAE due to position in the breast or had B3 pathology for which open biopsy was still required. The final decision to offer VAE was always made at a multidisciplinary meeting (MDM). Risk difference was used to test the significance at p ≤ .05. In total, 258 B3 lesions were diagnosed, 105 (40.7%) met the inclusion criteria and underwent VAE. VAE was performed under X-ray (89/105) or ultrasound guidance (16/105), taking an average of 18.5 cores with the 10-G needle or 10.8 cores with the 7-G needle. Nine cases (8.6%) were upgraded to a malignant diagnosis following VAE. Malignancy was found in 15.5% (9/58) of B3 lesions with epithelial atypia, but in none without atypia (0/47) (p = .004). No new lesions or malignancy has occurred at the site of the VAE with an average mammographic follow-up of 2.2 years. Upgrade to malignancy following VAE was uncommon (8.6%) and associated with atypia in the initial biopsy. VAE is an alternative approach to the management of B3 lesions, reducing open surgical procedures. • Upgrade to malignancy after a vacuum-assisted excision of a B3 breast lesion is uncommon with an 8.6% upgrade rate. • The risk of a malignant diagnosis after a vacuum-assisted excision was significantly higher for B3 lesions with atypia compared to those without (+15.5% difference, p = .004).

On the evaluation of mobile target trajectory between four-dimensional computer tomography and four-dimensional cone-beam computer tomography.

PurposeFor mobile lung tumors, four‐dimensional computer tomography (4D CT) is often used for simulation and treatment planning. Localization accuracy remains a challenge in lung stereotactic body radiation therapy (SBRT) treatments. An attractive image guidance method to increase localization accuracy is 4D cone‐beam CT (CBCT) as it allows for visualization of tumor motion with reduced motion artifacts. However, acquisition and reconstruction of 4D CBCT differ from that of 4D CT. This study evaluates the discrepancies between the reconstructed motion of 4D CBCT and 4D CT imaging over a wide range of sine target motion parameters and patient waveforms.MethodsA thorax motion phantom was used to examine 24 sine motions with varying amplitudes and cycle times and seven patient waveforms. Each programmed motion was imaged using 4D CT and 4D CBCT. The images were processed to auto segment the target. For sine motion, the target centroid at each phase was fitted to a sinusoidal curve to evaluate equivalence in amplitude between the two imaging modalities. The patient waveform motion was evaluated based on the average 4D data sets.ResultsThe mean difference and root‐mean‐square‐error between the two modalities for sine motion were −0.35 ± 0.22 and 0.60 mm, respectively, with 4D CBCT slightly overestimating amplitude compared with 4D CT. The two imaging methods were determined to be significantly equivalent within ±1 mm based on two one‐sided t tests (p < 0.001). For patient‐specific motion, the mean difference was 1.5 ± 2.1 (0.8 ± 0.6 without outlier), 0.4 ± 0.3, and 0.8 ± 0.6 mm for superior/inferior (SI), anterior/posterior (AP), and left/right (LR), respectively.ConclusionIn cases where 4D CT is used to image mobile tumors, 4D CBCT is an attractive localization method due to its assessment of motion with respect to 4D CT, particularly for lung SBRT treatments where accuracy is paramount.

Registration of Untracked 2D Laparoscopic Ultrasound to CT Images of the Liver Using Multi-Labelled Content-Based Image Retrieval.

Laparoscopic Ultrasound (LUS) is recommended as a standard-of-care when performing laparoscopic liver resections as it images sub-surface structures such as tumours and major vessels. Given that LUS probes are difficult to handle and some tumours are iso-echoic, registration of LUS images to a pre-operative CT has been proposed as an image-guidance method. This registration problem is particularly challenging due to the small field of view of LUS, and usually depends on both a manual initialisation and tracking to compose a volume, hindering clinical translation. In this paper, we extend a proposed registration approach using Content-Based Image Retrieval (CBIR), removing the requirement for tracking or manual initialisation. Pre-operatively, a set of possible LUS planes is simulated from CT and a descriptor generated for each image. Then, a Bayesian framework is employed to estimate the most likely sequence of CT simulations that matches a series of LUS images. We extend our CBIR formulation to use multiple labelled objects and constrain the registration by separating liver vessels into portal vein and hepatic vein branches. The value of this new labeled approach is demonstrated in retrospective data from 5 patients. Results show that, by including a series of 5 untracked images in time, a single LUS image can be registered with accuracies ranging from 5.7 to 16.4 mm with a success rate of 78%. Initialisation of the LUS to CT registration with the proposed framework could potentially enable the clinical translation of these image fusion techniques.

Experimental and numerical studies on kV scattered x-ray imaging for real-time image guidance in radiation therapy

Motion management is a critical component of image guided radiotherapy for lung cancer. We previously proposed a scheme using kV scattered x-ray photons for marker-less real-time image guidance in lung cancer radiotherapy. This study reports our recent progress using the photon counting detection technique to demonstrate potential feasibility of this method and using Monte Carlo (MC) simulations and ray-tracing calculations to characterize the performance. In our scheme, a thin slice of x-ray beam was directed to the target and we measured the outgoing scattered photons using a photon counting detector with a parallel-hole collimator to establish the correspondence between detector pixels and scatter positions. Image corrections of geometry, beam attenuation and scattering angle were performed to convert the raw image to the actual image of Compton attenuation coefficient. We set up a MC simulation system using an in-house developed GPU-based MC package modeling the image formation process. We also performed ray-tracing calculations to investigate the impacts of imaging system geometry on resulting image resolution. The experiment demonstrated feasibility of using a photon counting detector to measure scattered x-ray photons and generate the proposed scattered x-ray image. After correction, x-ray scattering image intensity and Compton scattering attenuation coefficient were linearly related, with R 2 greater than 0.9. Contrast to noise ratios of different objects were improved and the values in experimental results and MC simulation results agreed with each other. Ray-tracing calculations revealed the dependence of image resolution on imaging geometry. The image resolution increases with reduced source to object distance and increased collimator height. The study demonstrated potential feasibility of using scattered x-ray imaging as a real-time image guidance method in radiation therapy.

Peripheral Nerve Stimulation for the 21st Century: Sural, Superficial Peroneal, and Tibial Nerves

Peripheral nerve stimulation (PNS) of the lower extremity has progressed significantly over the last decade. From the proof of concept that ultrasound-guided, percutaneous implantation was possible to advances in waveforms, the field has been rapidly evolving. While most nerves in the lower extremity can be PNS targets, consideration must be given to the ergonomics of pulse generator placement, patient comfort, and avoidance of lead migration. For this paper, we examine some of the conditions amenable to lower extremity PNS, review the evidence and history behind PNS for these conditions, and describe approaches for the tibial, sural, and superficial peroneal nerves. A literature search was conducted using PubMed. Search terms used were "peripheral nerve stimulation," "lower extremity entrapment neuropathies," "sural nerve," "superficial peroneal nerve," "tibial nerve," and "tarsal tunnel syndrome." Emphasis was placed on randomized controlled studies, anatomical dissections, and comprehensive review articles. Approaches to nerves and ultrasound images were based on anecdotal PNS cases from an experienced implanter (SP). The development of ultrasound as a viable method of image guidance for percutaneous peripheral nerve stimulation has led to an exponential growth in the field. Lower extremity percutaneous lead placement is both feasible and an appropriate treatment modality for certain pain conditions.

Computed tomography as a method of control of percutaneous tumor cryoablation

Purpose: to develop methodological aspects of CT navigation and control of tumor cryoablation. Methods and materials . The study included 38 patients with malignant neoplasms of different localization, who underwent 58 cryoablation procedures with CT navigation. CT control was performed in sequential mode, in the mode of CT fluoroscopy or as an part of robot-assisted operations. The accuracy of cryoprobe positioning and the possibility of visual control of the ice-ball propagation were evaluated. Results: in all cases of cryoablation the use of CT made it possible to install accurately cryoprobes in the tumor and visually control the formation of the ice-sphere. Conclusion : CT is the optimal method of image guidance for cryoablation, which allows to control both the positioning of cryoprobes in the tumor and the process of ice front propagation. Depending on the characteristics of the tumor, technical equipment and experience of the operator, one or another method of CT navigation of instruments can be chosen.

Echocardiography-Guided Dual-Lumen Venovenous Extracorporeal Membrane Oxygenation Cannula Placement in the ICU—A Retrospective Review

The most effective method of image guidance for venovenous extracorporeal membrane oxygenation is not known. The authors' objectives were to define the frequency of successful initial cannulation using echocardiographic guidance in the intensive care unit, as well as to determine the frequency of subsequent adjustments. Additional aims were to illustrate cannula malposition problems and to describe features associated with difficult cannulation. Retrospective consecutive case series analysis. Single tertiary care university hospital. Forty-five patients treated with venovenous extracorporeal membrane oxygenation. None. The most common causes of respiratory failure were pneumonia, aspiration, and inhalational burn injury. Sixty-two percent survived to discharge. Initial cannulation was successful in 39 cases (87%). Adverse events included 5 cases of cannula malposition and 1 case of hemorrhagic shock. During the course of extracorporeal membrane oxygenation, 17 patients (38%) required echo-guided cannula position adjustments. There were no fatal complications. Factors associated with difficult cannulation included extremes of size, a prominent Eustachian valve, and an anterior guidewire bending in the right atrium. Younger age was associated positively with survival. There was no significant association between adverse events during cannulation and survival. Dual-lumen venovenous extracorporeal membrane oxygenation cannulation in the intensive care unit under echo guidance has a high initial success rate, but many patients require subsequent repositioning. Echocardiography can define cannula position in sufficient detail to identify malposition precisely and to guide repositioning.

MR and CT arthrography in cartilage imaging : Indications and implementation

The imaging of chondral pathologies is an essential part in the work-up of acute and chronic joint diseases. Besides conventional MR imaging, CT and MR arthrography are well-established methods in evaluating articular cartilage. The application of these techniques requires knowledge of indications and safe injection procedures by the performing radiologist. Our goal is to describe the techniques of cross-sectional arthrographies of different joints, give an overview of general and joint-specific considerations for practical application as well as provide typical indications for cartilage imaging. Aselective PubMed literature search concerning "arthrography", "CT arthrography", "MR arthrography", "arthrography cartilage", "arthrography wrist", "arthrography elbow", "arthrography shoulder", "arthrography hip", "arthrography knee", "arthrography ankle", "arthrography complications", "arthrography imaging guidance" "osteochondral lesion", "cartilage imaging" and "cartilage lesion" was performed. CT and MR arthrography are valuable and safe tools in cartilage imaging. They are useful to verify and specify chondral pathologies, usually after conventional MR imaging, and have an important role in evaluating the stability and therefore in therapeutic decision making of osteochondral lesions. CT arthrography is not only asubstitute technique in case of MR contraindications, it can be advantageous in small joints (wrist, elbow, ankle) compared to MR arthrography due to its higher image resolution. Fluoroscopic guided joint puncture is still the most commonly used image guidance method, but the role of ultrasound is steadily increasing. Joint traction in MR arthrography is apromising technique to improve cartilage visualization, though it is not yet used in clinical routine imaging.

Assessing the Need for Preprocedural Laboratory Tests and Stopping Non-steroidal Anti-inflammatory Drugs/Aspirin in Patients Undergoing Percutaneous Bone and Soft Tissue Biopsies.

Although image-guided biopsies of bone and soft tissue lesions have a low complication rate, there is limited data evaluating use of preprocedural laboratory tests. To address this issue, patients were not required to stop non-steroidal antiinflammatory drugs (NSAIDs) and aspirin or to obtain preprocedural laboratory tests [complete blood count (CBC) and international normalized ratio (INR)], except in special circumstances. The bleeding complication rate, rate of same day biopsies, and the time from when the biopsy was ordered to when it was performed were obtained. A total of 332 patients who underwent bone or soft tissue biopsies performed at our institution between 9/1/2017 and 1/9/2019 were prospectively analyzed. These data were compared to a retrospective biopsy cohort of 323 patients between 7/1/2015 and 7/1/2017. Data collected included method of image guidance and bleeding complication rate. The number of days from ordering to performing a biopsy and number of same day biopsies were recorded. There were no bleeding complications in either cohort (OR 1.00, P = 1). The mean time from ordering to performing a bone biopsy was significantly decreased in the prospective group (6.6days) compared to the retrospective group (8.1days) (P = 0.012). There were more same day biopsies in the prospective cohort (11.4% vs. 3.4%) (P < 0.001). Preprocedural CBC and INR for bone and soft tissue biopsies can be safely eliminated in most patients. Biopsies performed while patients are taking NSAIDs/aspirin can safely be performed. Adopting revised preprocedural laboratory criteria can result in decreased time to completion of biopsies.

Ultrasound-guided percutaneous rib biopsy: a safe procedure with high diagnostic yield

To assess the diagnostic yield and complication rate of image-guided percutaneous rib biopsy, comparing ultrasonography (US) to fluoroscopy and computed tomography (CT)-guided biopsy techniques. A retrospective review was conducted of patients who underwent image-guided percutaneous rib biopsy at a single tertiary-care academic centre between January 2007 and June 2017. The diagnostic yield and complication rates were calculated and compared between the three imaging methods. A total of 70 consecutive, image-guided percutaneous rib biopsies were performed in 67 patients (48 in males, 22 in females, mean age of 68.2 years, age range 31-92 years). The image guidance method utilised for biopsy was US in 64.3% (45/70), CT in 18.6% (13/70), and fluoroscopy in 17.1% (12/70). The diagnostic yield for all cases combined was 97.1% (68/70) and 97.8% (44/45) for US-guided biopsies specifically. A complication of pneumothorax was encountered in 4.3% (3/70) of all cases combined and in 4.4% (2/45) of US-guided biopsies specifically. US-guided percutaneous rib biopsy has a high diagnostic yield and low complication rate, comparable to fluoroscopy or CT-guided biopsy.

Reconstructed and Real Proton Radiographs for Image-Guidance in Proton Beam Therapy.

One of the major challenges to proton beam therapy at this time is the uncertainty of the true range of a clinical treatment proton beam as it traverses the various tissues and organs in a human body. This uncertainty necessitates the addition of greater "margins" to the planning target volume along the direction of the beam to ensure safety and tumor target coverage. Proton radiography holds promise as both an image-guidance method for proton beam therapy and as a means of estimating particle beam range in the clinic. In this brief report, we present some of the first real and reconstructed proton radiographs using our particular system. Our qualitative review of these images indicates that this method has excellent potential as a proton radiography-based image guidance system. Based on the encouraging results of our preliminary work, more rigorous and quantitative analyses will be performed shortly and we shall continue to explore the potential of this approach for addressing the particle beam range uncertainty issue.