Web-Based GPU-Accelerated Application for Multiplanar Reconstructions from Conventional 2D Ultrasound.

PURPOSE: In ultrasound education there is a need for interactive web-based learning resources. The purpose of this project was to develop a web-based application that enables the generation and exploration of volumetric datasets from cine loops obtained with conventional 2D ultrasound. MATERIALS AND METHODS: JavaScript code for ultrasound video loading and the generation of volumetric datasets was created and merged with an existing web-based imaging viewer based on JavaScript and HTML5. The Web Graphics Library was utilized to enable hardware-accelerated image rendering. RESULTS: The result is a web application that works in most major browsers without any plug-ins. It allows users to load a conventional 2D ultrasound cine loop which can subsequently be manipulated with on-the-fly multiplanar reconstructions as in a Digital Imaging and Communications in Medicine (DICOM) viewer. The application is freely accessible at (http://www.castlemountain.dk/atlas/index.php?page=mulrecon&mulreconPage=sonoviewer) where a demonstration of web-based sharing of generated cases can also be found. CONCLUSION: The developed web-based application is unique in its ability to easily perform loading of one's own ultrasound clips and conduct multiplanar reconstructions where interactive cases can be shared on the Internet.

Web-based imaging viewer for real-color volumetric reconstruction of human visible project and DICOM datasets.

Anatomy remains a cornerstone of medical education. It is vital that students achieve a robust understanding of the spatial relationships between anatomical structures in three dimensions. Volumetric medical imaging studies and true-color cryosectional three-dimensional images of visible human datasets are useful for enhancing anatomy education. However, the software systems available for viewing these datasets have important limitations. A web-based application called Mulrecon Color, which can overcome a number of those limitations, is introduced. Mulrecon Color enables volumetric medical and full color cryosectional datasets to be explored without requiring installation, and can therefore be used on a broad range of desktop, mobile, and even virtual reality devices. The web-based application has an interface that resembles a DICOM viewer used in radiological practice, and can be used both in anatomical labs and off campus for self-study. The Mulrecon Color application is released as an open source tool. It can be retrieved at a project website where sample datasets are also available.

On Jones et al.'s method for extending Bland-Altman plots to limits of agreement with the mean for multiple observers.

BACKGROUND: To assess the agreement of continuous measurements between a number of observers, Jones et al. introduced limits of agreement with the mean (LOAM) for multiple observers, representing how much an individual observer can deviate from the mean measurement of all observers. Besides the graphical visualisation of LOAM, suggested by Jones et al., it is desirable to supply LOAM with confidence intervals and to extend the method to the case of multiple measurements per observer. METHODS: We reformulate LOAM under the assumption the measurements follow an additive two-way random effects model. Assuming this model, we provide estimates and confidence intervals for the proposed LOAM. Further, this approach is easily extended to the case of multiple measurements per observer. RESULTS: The proposed method is applied on two data sets to illustrate its use. Specifically, we consider agreement between measurements regarding tumour size and aortic diameter. For the latter study, three measurement methods are considered. CONCLUSIONS: The proposed LOAM and the associated confidence intervals are useful for assessing agreement between continuous measurements.

Superior Reproducibility of the Leading to Leading Edge and Inner to Inner Edge Methods in the Ultrasound Assessment of Maximum Abdominal Aortic Diameter.

OBJECTIVES: Controversy exists regarding optimal caliper placement in ultrasound assessment of maximum abdominal aortic diameter. This study aimed primarily to determine reproducibility of caliper placement in relation to the aortic wall with the three principal methods: leading to leading edge (LTL), inner to inner edge (ITI), and outer to outer edge (OTO). The secondary aim was to assess the mean difference between the OTO, ITI, and LTL diameters and estimate the impact of using either of these methods on abdominal aortic aneurysm (AAA) prevalence in a screening program. METHODS: Radiologists (n=18) assessed the maximum antero-posterior abdominal aortic diameter by completing repeated caliper placements with the OTO, LTL, and ITI methods on 50 still abdominal aortic images obtained from an AAA screening program. Inter-observer reproducibility was calculated as the limit of agreement with the mean (LoA), which represents expected deviation of a single observer from the mean of all observers. Intra-observer reproducibility was assessed averaging the LoA for each observer with their repeated measurements. Based on data from an AAA screening trial and the estimated mean differences between the three principal methods, AAA prevalence was estimated using each of the methods. RESULTS: The inter-observer LoA of the OTO, ITI, and LTL was 2.6, 1.9, and 1.9 mm, whereas the intra-observer LoA was 2.0, 1.6, and 1.5 mm, respectively. Mean differences of 5.0 mm were found between OTO and ITI measurements, 2.6 mm between OTO and LTL measurements, and 2.4 mm between LTL and ITI measurements. The prevalence of AAA almost doubled using OTO instead of ITI, while the difference between ITI and LTL was minor (3.3% vs. 4.0% AAA). CONCLUSIONS: The study shows superior reproducibility of LTL and ITI compared with the OTO method of caliper placement in ultrasound determination of maximum abdominal aortic diameter, and the choice of caliper placement method significantly affects the prevalence of AAAs in screening programs.

Towards AI-augmented radiology education: a web-based application for perception training in chest X-ray nodule detection.

OBJECTIVES: Artificial intelligence (AI)-based applications for augmenting radiological education are underexplored. Prior studies have demonstrated the effectiveness of simulation in radiological perception training. This study aimed to develop and make available a pure web-based application called Perception Trainer for perception training in lung nodule detection in chest X-rays. METHODS: Based on open-access data, we trained a deep-learning model for lung segmentation in chest X-rays. Subsequently, an algorithm for artificial lung nodule generation was implemented and combined with the segmentation model to allow on-the-fly procedural insertion of lung nodules in chest X-rays. This functionality was integrated into an existing zero-footprint web-based DICOM viewer, and a dynamic HTML page was created to specify case generation parameters. RESULTS: The result is an easily accessible platform-agnostic web application available at: https://castlemountain.dk/mulrecon/perceptionTrainer.html.The application allows the user to specify the characteristics of lung nodules to be inserted into chest X-rays, and it produces automated feedback regarding nodule detection performance. Generated cases can be shared through a uniform resource locator. CONCLUSION: We anticipate that the description and availability of our developed solution with open-sourced codes may help facilitate radiological education and stimulate the development of similar AI-augmented educational tools. ADVANCES IN KNOWLEDGE: A web-based application applying AI-based techniques for radiological perception training was developed. The application demonstrates a novel approach for on-the-fly generation of cases in chest X-ray lung nodule detection employing deep-learning-based segmentation and lung nodule simulation.

Dataset on renal tumor diameter assessment by multiple observers in normal-dose and low-dose CT.

Computed tomography-based active surveillance is increasingly used to manage small renal tumors, regardless of patient age. However, there is an unmet need for decreasing radiation exposure while maintaining the necessary accuracy and reproducibility in radiographic measurements, allowing for detecting even minor changes in renal mass size. In this article, we present supplementary data from a multiobserver investigation. We explored the accuracy and reproducibility of low-dose CT (75% dose reduction) compared to normal-dose CT in assessing maximum axial renal tumor diameter. Open-access CT datasets from the 2019 Kidney and Kidney Tumor Segmentation Challenge were used. A web-based platform for assessing observer performance was used by six radiologist observers to obtain and provide data on tumor diameters and accompanying viewing settings, in addition to key images of each measurement and an interactive module for exploring diameter measurements. These data can serve as a baseline and inform future studies investigating and validating lower-dose CT protocols for active surveillance of small renal masses.

Inter- and intra-observer variability of computed tomography-based parenchymal- and ductal diameters in chronic pancreatitis: a multi-observer international study.

PURPOSE: The need for incorporation of quantitative imaging biomarkers of pancreatic parenchymal and ductal structures has been highlighted in recent proposals for new scoring systems in chronic pancreatitis (CP). To quantify inter- and intra-observer variability in CT-based measurements of ductal- and gland diameters in CP patients. MATERIALS AND METHODS: Prospectively acquired pancreatic CT examinations from 50 CP patients were reviewed by 12 radiologists and four pancreatologists from 10 institutions. Assessment entailed measuring maximum diameter in the axial plane of four structures: (1) pancreatic head (PDhead), (2) pancreatic body (PDbody), (3) main pancreatic duct in the pancreatic head (MPDhead), and (4) body (MPDbody). Agreement was assessed by the 95% limits of agreement with the mean (LOAM), representing how much a single measurement for a specific subject may plausibly deviate from the mean of all measurements on the specific subject. Bland-Altman limits of agreement (LoA) were generated for intra-observer pairs. RESULTS: The 16 observers completed 6400 caliper placements comprising a first and second measurement session. The widest inter-observer LOAM was seen with PDhead (± 9.1 mm), followed by PDbody (± 5.1 mm), MPDhead (± 3.2 mm), and MPDbody (± 2.6 mm), whereas the mean intra-observer LoA width was ± 7.3, ± 5.1, ± 3.7, and ± 2.4 mm, respectively. CONCLUSION: Substantial intra- and inter-observer variability was observed in pancreatic two-point measurements. This was especially pronounced for parenchymal and duct diameters of the pancreatic head. These findings challenge the implementation of two-point measurements as the foundation for quantitative imaging scoring systems in CP.

Ultra-low-dose non-contrast CT and CT angiography can be used interchangeably for assessing maximal abdominal aortic diameter.

Background: Routine CT scans may increasingly be used to document normal aortic size and to detect incidental abdominal aortic aneurysms. Purpose: To determine whether ultra-low-dose non-contrast CT (ULDNC-CT) can be used instead of the gold standard CT angiography (CTA) for assessment of maximal abdominal aortic diameter. Materials and Methods: This retrospective study included 50 patients who underwent CTA and a normal-dose non-contrast CT for suspected renal artery stenosis. ULDNC-CT datasets were generated from the normal-dose non-contrast CT datasets using a simulation technique. Using the centerline technique, radiology consultants (n = 4) and residents (n = 3) determined maximal abdominal aortic diameter. The limits of agreement with the mean (LOAM) was used to access observer agreement. LOAM represents how much a measurement by a single observer may plausibly deviate from the mean of all observers on the specific subject. Results: Observers completed 1400 measurements encompassing repeated CTA and ULDNC-CT measurements. The mean diameter was 24.0 and 25.0 mm for CTA and ULDNC-CT, respectively, yielding a significant but minor mean difference of 1.0 mm. The 95% LOAM reproducibility was similar for CTA and ULDNC-CT (2.3 vs 2.3 mm). In addition, the 95% LOAM and mean diameters were similar for CTA and ULDNC-CT when observers were grouped as consultants and residents. Conclusions: Ultra-low-dose non-contrast CT exhibited similar accuracy and reproducibility of measurements compared with CTA for assessing maximal abdominal aortic diameter supporting that ULDNC-CT can be used interchangeably with CTA in the lower range of aortic sizes.

Gangrene of the Kidney Following Percutaneous Renal Cryoablation of a Small Tumor.

Background: In selected cases cryoablation is a valid treatment option for small renal masses. The procedure is generally considered oncologically efficient with a low rate of severe complications. We report here a case of a 62-year-old man who after percutaneous cryoablation develops severe gangrene in the treated kidney. Case Presentation: A 62-year-old man was incidentally diagnosed with a 45-mm renal cell carcinoma. The tumor was found on a CT scan performed on the suspicion of diverticulitis. An abscess in relation to the sigmoid was found and he was treated with aspiration and antibiotics. The tumor was treated with percutaneous cryoablation 20 days later. On the third postoperative day, he was readmitted with urosepsis. A CT scan revealed gangrene at the ablation site, and a nephrectomy was performed. Clinical progress was slow, and a new CT scan showed reformation of the abscess at the sigmoid and a suspicion of a colonic tumor was raised. This was confirmed by coloscopy and biopsy. The patient had a right hemicolectomy, and the pathology report described a T4 adenocarcinoma with positive margins. After 4 months follow-up, metastases to the lungs was found and the patient was referred to further oncologic treatment. Conclusion: Renal cryoablation is generally a very safe procedure, but severe complications may occur. This case report highlights that attention should be given to recent abdominal infections and that delayed intervention might be in place in selected cases.

Renal cryoablation: five- and 10-year survival outcomes in patients with biopsy-proven renal cell carcinoma.

OBJECTIVE: To investigate the long-term oncological efficacy of renal cryoablation (CA) of small renal tumors. MATERIALS AND METHODS: A review of patients treated with CA for a biopsy confirmed renal cell carcinoma less than 4 cm in diameter. All patients were identified from a prospectively maintained clinical database. Treatment efficacy was computed using the Kaplan-Meier method to estimate disease-free survival (DFS) and overall survival rates (OS). RESULTS: A total of 179 patients (116 men and 63 women) with a mean age of 64 years (95% CI = 63 - 66) were included in the analysis. Mean tumor size was 27 mm (95% CI = 25.5-28.0) with a low, moderate and high PADUA complexity score in 30.2%, 44.7% and 16.2% of the cases, respectively. A total of 19 patients (11%) were diagnosed with residual unablated tumor, six patients (3%) were diagnosed with late local recurrence and six patients (3%) were diagnosed with metastatic disease. The estimated 5 years image confirmed the DFS rate was 79% (95% CI = 70-85). The estimated 5- and 10-year OS rates were 82% (95% CI = 75-87) and 61% (95% CI = 48-71), respectively. During the 10-year follow-up period a total of five patients (3%) died due to renal cancer, while 46 patients (26%) died from other causes. CONCLUSIONS: CA appears to be an effective treatment modality for patients with small renal tumors. The present study demonstrated low rates of local recurrence and disease progression with excellent long-term cancer-specific survival.

CT-guided cryoablation of renal cancer: radiation burden and the associated risk of secondary cancer from procedural- and follow-up imaging.

OBJECTIVES: To estimate radiation dose and the associated risk of secondary cancer risk related to percutaneous cryoablation (PCA) and follow-up imaging in a cohort of patients treated for small renal masses (SRMs). METHODS: A total of 149 patients underwent PCA for a SRM at our institution. Based on CT dose reports, we calculated the mean effective dose for a CT-guided PCA procedure and post-ablative follow-up CT. Applying follow-up recommendations by a multidisciplinary expert panel, we calculated the total radiation dose for the PCA procedure and the CT surveillance program corresponding to a minimal and preferable follow-up regime (5-year vs 10-year). Estimates of the lifetime attributable cancer risk for different age groups were calculated based on the cumulative effective dose based on the latest BEIR VII report. RESULTS: Total dose for the PCA treatment and follow-up CTs amounted to 174 and 294 mSv for a minimal and preferable protocol, respectively. Follow-up CTs accounted for the majority of the total effective dose for the minimal and preferable protocol (89% vs 94%). CT fluoroscopy contributed only to a limited amount of the total radiation dose for the minimal and preferable protocol (1.8% vs 1.1%). A 70-year-old male undergoing PCA treatment has a lifetime attributable cancer risk of 0.8% (1 in 131) when completing the preferable follow-up protocol. The same regimen in a 30-year-old female results in a lifetime attributable risk of cancer of 3.4% (1 in 29). CONCLUSION: Radiation dose and the associated risk of secondary cancer are high for patients with SRMs undergoing PCA and post-ablative follow-up imaging in particular in younger patients. Radiation exposure in the PCA procedure itself accounts for only a limited amount of the total radiation. Radiologists and clinicians must strive to implement radiation dose saving measures especially with respect to the follow-up regime.

MULRECON: A Web-based Imaging Viewer for Visualization of Volumetric Images.

Recent developments in web technology allow pixel-level manipulation of radiologic images. This paper presents an easily accessible imaging viewer for visualization of volumetric datasets which leverages modern web technology. The viewer is designed to enable on-the-fly multiplanar reconstructions with different projectional techniques, and these can be manipulated as in a Picture Archiving and Communication System. The application opens up possibilities for teaching and demonstrational purposes. Step-by-step instructions for how to use are provided and the source code is made available.

Patient Self-Assessed Passive Range of Motion of the Knee Cannot Replace Health Professional Measurements.

The purpose of this study was to investigate whether patients can accurately self-assess their knee passive range of motion (PROM). A picture-based questionnaire for patient self-assessment of knee PROM was developed and posted to patients. The self-assessed PROM from 58 patients was compared with surgeon-assessed PROM using a short-arm goniometer. Agreement between the measurement methods was calculated with the Bland-Altman method. We calculated the sensitivity and specificity of patient-assessed PROM in dichotomously detecting knee motion impairment in both flexion (≤ 100 degrees) and extension (≥ 10-degree flexion contracture). Surgeon- and patient-assessed knee PROM showed a mean difference (95% limits of agreement) of -2.1 degrees (-42.5 to 38.3 degrees) for flexion and -8.1 degrees (-28.8 to 12.7 degrees) for extension. The sensitivity of patient self-assessed PROM in identifying knee flexion and extension impairments was 86 and 100%, respectively, whereas its specificity was 84 and 43%, respectively. Although wide limits of agreement were observed between surgeon- and patient-assessed knee PROM, the picture-based questionnaire for patient assessment of knee ROM was found to be a valid tool for dichotomously detecting knee motion impairment in flexion (≤ 100 degrees). However, the specificity of the questionnaire for detection of knee extension impairments (≥ 10-degree flexion contracture) was low, which limits is practical utility for this purpose.